JP2000310892A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain an initial image state of a product. SOLUTION: In this device, specified fixing test images TA to TC are formed on a recording medium S in the initial state (S1, S2). Then, initial glossiness of each of the fixing test images TA to TC are separately calculated and stored by a central control part based on the strength of reflected light, etc., obtained at an image information detection part (S3). Then, the fixing test images TA to TC are formed again periodically at a specified timing (S5 to S7). Next, the glossiness of each of the fixing test images TA to TC are calculated, compared with the initial glossiness and electrifying voltage value of a 1st to 3rd electrifying chargers are compensated based on the detected result (S8 to S14). Thus, if a condition for fixing is constant, since the toner attachment quantity is varied, the glossiness is also varied to be equivalent to the initial glossiness. Therefore, the state of image at the initial state is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile. More specifically, the present invention relates to an image forming apparatus that can maintain an image state in an initial state.

[0002]

2. Description of the Related Art For example, in an image forming apparatus such as an electrophotographic copying machine, a permanent image is obtained by fixing a toner image transferred to a recording medium. Here, as a fixing method, there are methods such as heat fixing, pressure fixing, and solvent fixing. Among them, a heat roller type fixing device using heat fixing is widely and generally used. As this fixing device, for example, a fixing device including a heating roller and a pressure roller is known. The heating roller is a metal roller having good heat conduction and small heat capacity. The heating roller has a heater lamp inside, and the surface temperature is detected by a thermistor or the like, and the temperature is controlled so as to be within a predetermined fixing temperature range. On the other hand, the pressing roller has a core material whose surface is coated with elastic silicon rubber or the like. The heating roller and the pressure roller are rotatably supported in a state where they are pressed against each other. When the recording material on which the toner image is transferred passes between the heating roller and the pressure roller, the toner melts. At the same time, the toner image is pressed against the recording medium to fix the toner image, thereby obtaining a permanent image. In the fixing device provided in the color image forming apparatus, the surface of the heating roller is also covered with silicone rubber.

[0003]

However, in the conventional apparatus, the image state of the fixed image fixed on the recording medium is smaller than that at the beginning of use of the apparatus or immediately after adjustment (initial state). There were times when it fluctuated. Moreover, the fluctuation does not always occur uniformly over the entire image, and the fluctuation width may be distributed in the recording medium conveyance direction or in a direction orthogonal thereto. However, in order to improve the fluctuation of the image state in the recording medium transport direction and the direction perpendicular thereto, adjustment, repair, replacement of parts, and the like must be performed by a serviceman, and there is a problem that it takes much time and effort. Was.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide an image forming apparatus capable of maintaining an image state in an initial state.

[0005]

According to the image forming apparatus of the present invention which has been made to solve the above-mentioned problems, a test image data obtaining means for obtaining test image data for creating a predetermined test image is provided. An image forming apparatus comprising: an image forming unit that forms an unfixed image on a recording medium; and a fixing unit that fixes the unfixed image generated by the image forming unit on the recording medium. Any one of the fixing unit and the fixing unit includes an image forming process condition changing unit that can change at least one or more process conditions among the respective process conditions of the image forming process in a direction orthogonal to the recording medium conveying direction;
A light-emitting element that irradiates light to the fixing test image fixed on the recording medium by the fixing unit; and a light-receiving element that detects intensity information of light that is emitted from the light-emitting element and reflects or transmits the fixing test image. Image information detecting means for detecting image information of the fixing test image in at least two or more positions of the recording medium in the initial state and at a predetermined detection timing, the positions in the direction orthogonal to the recording medium conveyance direction being different; Initial image information storage means for storing initial image information detected by the image information detection means in an initial state, detection timing determination means for determining the predetermined detection timing of the image information detection means, and detection timing determination means The image information detected by the image information detecting means at the determined detection timing and the initial image information storing means Image information comparing means for comparing the stored initial image information; and image forming process condition correcting means for correcting a process condition in the image forming process condition changing means based on a comparison result in the image information comparing means. .

In this image forming apparatus, first, an image forming means forms an unfixed image (toner image) on a recording medium. Here, the unfixed image created on the recording medium by the image creating means includes a copy image of a document to be copied, an image based on image data input to the image forming apparatus, and a predetermined test image based on test image data. included. The test image is created based on test image data obtained by a test image data obtaining unit from a memory in which test image data is stored in advance or from outside.

Next, the fixing means fixes the unfixed image created by the image creating means on the recording medium. Then, the image information detecting means detects the image information of the fixing test image in at least two or more places in the initial state and at a predetermined timing, the positions of which are different from each other in the direction orthogonal to the recording medium transport direction.

[0008] The image information of the fixing test image is detected by
First, it is performed in an initial state, that is, immediately after product repair or adjustment or part replacement by a service person. further,
The detection is also performed at a predetermined timing determined by the detection timing determining means. For example, it may be performed every 1000 sheets. The initial image information detected by the image information detecting means in the initial state is stored in the initial image information storing means.

The image information is detected by irradiating the fixing test image on the recording medium with light by the light emitting element and receiving light reflected or transmitted from the fixing test image by the light receiving element. Here, the image information refers to information related to the state of the image, such as the surface state, translucency, and coloring, for example, and includes any information as long as the image state can be known. Specifically, the intensity of transmitted light (transmittance), the intensity of reflected light (reflectance, glossiness), or the color shift (shift of lightness, hue, and saturation) of the fixing test image, and the like are listed.

Subsequently, the image information comparing means compares the image information detected at the detection timing determined by the detection timing determining means with the initial image information stored in the initial image information storage means. Then, the image forming process condition correcting unit corrects the process condition in the image forming process condition changing unit based on the comparison result of the image information comparing unit. By this correction, for example, the comparison result is reflected (feedback) on the development condition and the transfer condition so that the image state in the direction orthogonal to the recording medium conveyance direction in one recording body approaches the initial state. Control can be performed so that a fixed image is automatically obtained in a direction orthogonal to the transport direction to the same degree as the initial state. Therefore, it is possible to obtain a fixed image maintaining the image state in the initial state. The image information detected at the detection timing determined by the detection timing determining means may be stored in a memory or the like, like the initial image information.

The image forming process conditions refer to each process condition until a fixed image is formed on a recording medium.
Specifically, for example, development conditions, transfer conditions, fixing conditions, and the like are included. In addition to the plain paper, any recording medium may be used as long as it can fix an image, such as a thick paper, an OHP sheet, or a special paper coated with a resin. Further, any light emitting element may be used as long as it emits light in the visible light region.
For example, a halogen lamp, a light emitting diode, a semiconductor laser, and the like can be given. Further, the light receiving element may be any element having a sensitivity range that responds to light emitted from the light emitting element. For example, a CCD, a photodiode, and the like can be given.

Here, in order to obtain the reflectance and the transmittance, the intensity of the incident light is necessary in addition to the intensity of the reflected or transmitted light. Therefore, the intensity of the incident light may be separately detected in addition to the reflected light or the transmitted light. However, when the intensity of the incident light is known, such as when the intensity is constant, the evaluation can be performed only with the intensity of the reflected light or the transmitted light. In addition, in the measurement of the intensity of the incident light, a method of directly measuring the intensity using a half mirror or the like, and a method of indirectly measuring the applied voltage, the current consumption, the power consumption, and the like of the light emitting element can also be used. .

In the image forming apparatus according to the present invention, the image forming process condition varying means includes a plurality of chargers for applying a charge to the photoreceptor in a direction orthogonal to the recording medium conveying direction. It is preferable that the charging conditions are divided charging units that can be changed, and the image forming process condition correcting unit is a charging condition correcting unit that corrects the charging condition of each charger.

In this image forming apparatus, the image information detecting means detects the image information of the fixing test image in at least two or more locations of the recording medium different in the direction orthogonal to the recording medium transport direction. The detection by the image information detection means is performed in the initial state and at the detection timing determined by the detection timing determination means. Further, the image information comparing means compares the initial image information with the image information detected at a predetermined timing.

The charging condition correcting means corrects the charging condition of each charger in the divided charging means based on the comparison result of the image information comparing means. This allows
The charging condition in the axial direction of the photoconductor can be changed. It is known that if the fixing condition is constant, the image condition of the fixed image can be changed by changing the charging condition. Therefore, by reflecting (feeding back) the comparison result on the charging condition so that the image state in the direction orthogonal to the recording medium conveyance direction in one recording medium approaches the initial state, the image state in the direction orthogonal to the recording medium conveyance direction It is possible to automatically control the image so that the fixed image is almost the same as the initial state. Therefore, it is possible to obtain a fixed image maintaining the image state in the initial state.

Further, in the image forming apparatus according to the present invention, the image forming process condition changing means moves the developer carrier for supplying the developer to the electrostatic latent image on the photosensitive member in a direction perpendicular to the recording medium conveying direction. A developing bias voltage value applied to each of the plurality of developer carriers; and a developing bias voltage value applied to each of the plurality of developer carriers. It is also preferable to use a developing condition correcting means for correcting the voltage value.

In this image forming apparatus as well, the image information detecting means detects the image information of the fixing test image at at least two or more places on the recording medium which are different in the direction orthogonal to the recording medium conveyance direction. The detection by the image information detection means is performed in the initial state and at the detection timing determined by the detection timing determination means. Further, the image information comparing means compares the initial image information with the image information detected at a predetermined timing.

The developing condition correcting means corrects a developing bias voltage value applied to a developer carrying member provided in each developing device in the divided developing means based on the comparison result by the image information comparing means. Thereby, the developing condition in the axial direction of the photoconductor can be changed. As described above, if the fixing condition is constant, the image state of the fixed image can be changed by changing the developing condition. Therefore, by reflecting (feeding back) the comparison result on the developing bias voltage value so that the image state in the direction orthogonal to the recording medium conveyance direction in one recording body approaches the initial state, the image state is orthogonal to the recording medium conveyance direction. It is possible to control so that the fixed image is automatically formed in the same direction as the initial state. Therefore, it is possible to obtain a fixed image maintaining the image state in the initial state.

Further, in the image forming apparatus according to the present invention, the image forming process condition changing means moves the transfer device for transferring the visible image on the photosensitive member onto the recording material in a direction orthogonal to the recording material conveying direction. A plurality of transfer units, each of which is capable of changing any one of a transfer current and a transfer voltage in the plurality of transfer units; and the image forming process condition correcting unit includes any one of the transfer current and the transfer voltage in each of the transfer units. It is also preferable to use a transfer condition correcting means for correcting the following.

In this image forming apparatus as well, the image information detecting means detects the image information of the fixing test image in at least two or more places on the recording medium which are different in the direction perpendicular to the recording medium conveyance direction. The detection by the image information detection means is performed in the initial state and at the detection timing determined by the detection timing determination means. Further, the image information comparing means compares the initial image information with the image information detected at a predetermined timing.

Then, the transfer condition correcting means corrects one of the transfer current and the transfer voltage of each transfer device in the divided transfer means based on the comparison result by the image information comparing means. Thereby, the transfer condition in the axial direction of the photoconductor can be changed. Then, as described above, if the fixing condition is constant, the image state of the fixed image can be changed by changing the transfer condition. Therefore, 1
By reflecting (feeding back) the comparison result on the transfer current or the transfer voltage so that the image state in the direction perpendicular to the recording medium transport direction in the sheet recording medium approaches the initial state, in the direction perpendicular to the recording medium transport direction. It is possible to automatically control the image so that the fixed image is almost the same as the initial state. Therefore, it is possible to obtain a fixed image maintaining the image state in the initial state.

Further, in the image forming apparatus according to the present invention, the fixing means includes a plurality of heaters in a direction orthogonal to the recording medium conveying direction, and fixes the unfixed image on the recording medium by contact heating. The image forming process condition changing unit is a divided heating unit that can change the control temperature of each of the plurality of heaters, and the image forming process condition correcting unit is the contact heating and fixing unit. It is also preferable to use a fixing temperature correction means for correcting the fixing temperature.

In this image forming apparatus as well, the image information detecting means detects the image information of the fixing test image in at least two or more places on the recording medium which are different in the direction perpendicular to the recording medium conveyance direction. The detection by the image information detection means is performed in the initial state and at the detection timing determined by the detection timing determination means. Further, the image information comparing means compares the initial image information with the image information detected at a predetermined timing.

The fixing temperature correcting means corrects the axial fixing temperature of the contact heating fixing means based on the result of the comparison by the image information comparing means. The fixing temperature is corrected by changing the control temperature of each heater. Thereby, the fixing condition in the axial direction of the fixing unit can be changed. Accordingly, by reflecting (feeding back) the comparison result to the fixing temperature so that the image state in the direction perpendicular to the recording medium conveyance direction in one recording medium approaches the initial state, the image state in the direction perpendicular to the recording medium conveyance direction is obtained. It is possible to automatically control the image so that the fixed image becomes almost the same as the initial state. Therefore, it is possible to obtain a fixed image maintaining the image state in the initial state.

Further, according to the image forming apparatus of the present invention which has been made to solve the above-mentioned problems, the image forming apparatus further comprises a test image data obtaining means for obtaining test image data for generating a predetermined test image. An image forming apparatus comprising: an image forming unit that forms an unfixed image on a body; and a fixing unit that fixes the unfixed image created by the image forming unit on the recording body. A light-emitting element for irradiating the fixing test image fixed thereon with light, and a light-receiving element for detecting intensity information of light emitted from the light-emitting element and reflecting or transmitting the fixing test image, and an initial state and a predetermined state. Detecting image information of at least two or more fixing test images at different positions in the recording medium conveyance direction among the recording materials at the detection timing Image information detecting means, initial image information storing means for storing initial image information detected by the image information detecting means in the initial state, and detection timing determining means for determining the predetermined detection timing of the image information detecting means And image information comparing means for comparing the image information detected by the image information detecting means at the detection timing determined by the detection timing determining means with the initial image information stored in the initial image information storing means; and An image forming process condition correcting unit for correcting at least one of the process conditions of the image forming unit and the fixing unit in the recording medium conveying direction based on a comparison result of the information comparing unit.

In this image forming apparatus, first, the image forming means forms an unfixed image (toner image) on a recording medium. Here, the unfixed image created on the recording medium by the image creating means includes a copy image of a document to be copied, an image based on image data input to the image forming apparatus, and a predetermined test image based on test image data. included. The test image is created based on test image data obtained by a test image data obtaining unit from a memory in which test image data is stored in advance or from outside.

Next, the fixing means fixes the unfixed image created by the image creating means on the recording medium. Then, the image information detecting means detects the image information of the fixing test image in at least two or more places in the recording medium in which the position in the recording medium transport direction is different at a predetermined timing determined by the initial state and the detection timing determining means. I do. The initial image information detected in the initial state is stored in the initial image information storage unit.

Subsequently, the image information comparing means compares the image information detected at a predetermined detection timing with the initial image information stored in the initial image information storage means. Then, the image forming process condition correcting means corrects at least one of the process conditions of the image creating means and the fixing means based on the comparison result of the image information comparing means. In this process condition correction, a correction value is given as a function of time. Thereby, the comparison result is reflected (feedback) in the developing condition and the fixing condition (fixing speed) so that the image state in the recording medium transport direction in one recording body approaches the initial state, and the recording medium transport direction is thus improved. Can be automatically controlled so that the fixed image becomes almost the same as the initial state. Therefore, it is possible to obtain a fixed image maintaining the image state in the initial state.

In the image forming apparatus according to the present invention, the image forming means has a charging means for applying a charge to the photosensitive member, and the image forming process condition correcting means corrects a charging condition in the charging means. Preferably, it is a charging condition correcting means.

In this image forming apparatus, the image information detecting means detects the image information of the fixing test image at at least two or more places in the recording medium where the positions in the recording medium conveyance direction are different. The detection by the image information detection means is performed in the initial state and at the detection timing determined by the detection timing determination means. Further, the image information comparing means compares the initial image information with the image information detected at a predetermined timing.

Then, the charging condition correcting means corrects the charging condition in the charging means based on the comparison result in the image information comparing means. Thereby, the charging condition in the circumferential direction of the photoconductor can be changed. Then, as described above, if the fixing condition is constant, the image condition of the fixed image can be changed by changing the charging condition. Therefore,
By reflecting (feeding back) the comparison result in the charging condition so that the image state in the recording medium transport direction in one recording body approaches the initial state, the fixing is automatically performed in the recording medium transport direction at the same level as the initial state. It can be controlled to be an image. Therefore, it is possible to obtain a fixed image maintaining the image state in the initial state.

Further, in the image forming apparatus according to the present invention, the image forming means has a developer carrying member for carrying a developer for supplying a developer to the electrostatic latent image on the photosensitive member, Preferably, the image forming process condition correcting means is a developing condition correcting means for correcting a developing bias voltage value applied to the developer carrier.

In this image forming apparatus as well, the image information detecting means detects the image information of the fixing test image in at least two or more places on the recording medium where the positions in the recording medium conveyance direction are different. The detection by the image information detection means is performed in the initial state and at the detection timing determined by the detection timing determination means. Further, the image information comparing means compares the initial image information with the image information detected at a predetermined timing.

The developing condition correcting means corrects the value of the developing bias voltage applied to the developer carrier based on the result of the comparison by the image information comparing means. As a result, development conditions in the circumferential direction of the photoconductor can be changed.
Then, as described above, if the fixing condition is constant, the image state of the fixed image can be changed by changing the developing condition. Accordingly, by reflecting (feeding back) the comparison result to the developing bias value so that the image state in the recording medium transport direction in one recording medium approaches the initial state, the image state is automatically set to the initial state in the recording medium transport direction. It can be controlled so as to obtain a fixed image of a degree. Therefore, it is possible to obtain a fixed image maintaining the image state in the initial state.

Further, in the image forming apparatus according to the present invention, the image forming means includes a transfer means for transferring a visible image on a photoreceptor onto the recording medium, and the image forming process condition correcting means comprises: It is also preferable that the transfer means is a transfer condition correcting means for correcting either the transfer current or the transfer voltage in the transfer means.

In this image forming apparatus as well, the image information detecting means detects the image information of the fixing test image at at least two or more places on the recording medium where the positions in the recording medium conveyance direction are different. The detection by the image information detection means is performed in the initial state and at the detection timing determined by the detection timing determination means. Further, the image information comparing means compares the initial image information with the image information detected at a predetermined timing.

Then, the transfer condition correcting means corrects one of the transfer current and the transfer voltage in the transfer means based on the result of the comparison by the image information comparing means. As a result, development conditions in the circumferential direction of the photoconductor can be changed. Then, as described above, if the fixing condition is constant, the image state of the fixed image can be changed by changing the transfer condition. Therefore, the image state in one recording medium in the recording medium conveyance direction is approximated to the initial state.
By reflecting (feeding back) the comparison result in the transfer condition, it is possible to automatically control the fixed image in the conveyance direction of the recording medium so that the fixed image is almost the same as the initial state. Therefore, it is possible to obtain a fixed image maintaining the image state in the initial state.

[0038]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of an image forming apparatus according to the present invention. First, the first embodiment will be described. The first embodiment is an electrophotographic copying machine in which the image forming apparatus according to the present invention is mounted. This is to correct the charging condition of the charging charger that applies a charge to the photosensitive drum based on the charging condition.

As shown in FIG. 1, the copying machine 1 comprises an image reader section IR and a page printer section PRT. Then, based on the image data transferred from the image reader section IR, the page printer section PRT prints the image of the document by an electrophotographic process.

The image reader section IR includes an original glass 10
An image reading unit 2 that detects reflected light from an image of a document set thereon, photoelectrically converts the reflected light, and reads image data corresponding to the image of the document, and an image that performs data processing according to various image forming modes. And a processing unit 3. Note that the image reading section 2 includes a data memory section 9 for temporarily storing the read image data. A document cover 11 for holding a document is mounted above the image reader IR.

On the other hand, the page printer section PRT has an optical scanning section 4, an image processing section 5, and a transport section 6.
The optical scanning section 4 includes a polygon mirror 21 and a reflection mirror 22 for scanning and irradiating the photosensitive drum 30 with laser light. The image processing unit 5 includes a photosensitive drum 30, a charging charger 31, and developing units 32Y and 3
2C, 32M, 32K, a transfer drum 34 having a transfer charger 33, and a cleaning device 35. The transport unit 6 includes a paper cassette 44 for stacking and storing the recording medium.
And various transport rollers for transporting the recording medium supplied from the paper cassette 44 or the manual feed tray 45; the fixing device 40; and the halogen lamps 41A, 41B, 41C, and C.
An image information detection unit 43 including CD sensors 42A, 42B, and 42C, and a paper discharge tray 46 for storing a recording body that has been copied and discharged outside the apparatus are provided.

As shown in FIG. 2, the charging charger 31 includes three charging chargers, that is, a first charging charger 31A, a second charging charger 31B, and a third charging charger 31C. And FIG.
As shown in FIG. 3, the first charging charger 31A and the third charging charger 31C are provided at the same angular position in the circumferential direction of the photosensitive drum 30, and the second charging charger 31B is connected to the first charging charger 31A and the third charging charger 31.
C is provided at an angular position different from C (an angular position slightly advanced in the rotation direction of the photosensitive drum 30).

These chargers 31A to 31C
Have power supplies 311A to 311C and charge wires 312A to 312C, respectively.
Each 311C is connected to a high-voltage control unit 58 (see FIG. 7) described later. Then, by the high-pressure control unit 58,
First charging charger 31A, second charging charger 31
B and the third charging charger 31C can apply a charge to the surface of the photosensitive drum 30 under different charging conditions. Note that a fixing test image TA (see FIG. 5), which will be described later, is created in a region where the first charging charger 31A applies a charge to the photosensitive drum 30.
In a similar relationship, the fixing test image TB is applied to the area where the second charging charger 31B applies electric charge to the photosensitive drum 30.
Is generated, and a fixing test image TC is generated in a region where the third charging charger 31C applies a charge to the photosensitive drum 30.

The fixing device 40 is composed of a heating roller 212 and a pressure roller 213 arranged vertically, and details thereof will be described with reference to FIG. FIG. 4 shows a cross section of the fixing device 40 in the longitudinal direction. As shown in FIG. 4, the heating roller 212
Silicon rubber 212 is provided on the surface of a metal cylinder 212a made of a material such as aluminum having good heat conduction and small heat capacity.
b. A heater lamp 221 is provided inside the heating roller 212, and is supplied with power and heated based on temperature control by a general control unit 54 (see FIG. 7) described later. The surface temperature of the heating roller 212 is detected by a temperature sensor 222 such as a thermistor provided in contact with the surface. The surface temperature signal detected here is
It is input to the overall control unit 54 described later. On the other hand, similarly to the heating roller 212, the pressing roller 213 has a silicon cylinder 21a in a metal cylinder 213a having a heater lamp 221 therein.
3b.

When the pressure roller 213 is driven by a drive control unit 55 (see FIG. 7) described later, the heating roller 212 also rotates following the pressure roller 213. Note that, instead of the pressing roller 213, the heating roller 212 may be driven by the drive control unit 55, and the pressing roller 213 may be rotated by following the heating roller 212.

The image information detecting section 43 is for detecting image information of the fixed image. Specifically, the glossiness of the fixed image ((specular reflection light amount / incident light amount) × 100 =
(Specular reflectance). As shown in FIG. 5, for example, as shown in FIG. 5, the image information detection unit 43 includes three substantially rectangular fixing test images TA, When TB and TC are formed on the recording medium S, the fixing test image TA
And so on so that the intensity of the specularly reflected light can be measured. In other words, the image information detection unit 43 is configured to intersect with the direction in which the recording medium S is conveyed (in this embodiment, the direction orthogonal to the conveyance direction).
, And a set of three light emitting elements and light receiving elements (light emitting / light receiving element pairs). Thereby, it is possible to grasp the variation in glossiness in a direction perpendicular to the recording medium conveyance direction in one recording medium.

Specifically, the halogen lamp 41A and the CC
D sensor 42A, halogen lamp 41B and CCD sensor 42B, and halogen lamp 41C and CCD sensor 4
It is composed of three pairs of light emitting / receiving elements 2C. The halogen lamp 41A and the CCD sensor 42A are arranged at positions where the intensity of the reflected light of the fixing test image TA can be measured. That is, in the conveyance path of the recording medium S, behind the fixing device 40, a halogen lamp, which is a light emitting element, is positioned obliquely upper right (diagonally upper in the anti-conveying direction) in FIG. 41A is provided to receive specularly reflected light with respect to the incident light incident on the fixing test image TA from the halogen lamp 41A.
A CCD sensor 42A, which is a light receiving element, is provided on the upper left side (in the transport direction) of FIG. 1 where the incident angle α and the reflection angle β with respect to the fixing test image TA (recording medium S) are equal. In a similar positional relationship, the halogen lamp 41
B, CCD sensor 42B, and halogen lamp 41C
And a CCD sensor 42C. Note that the specularly reflected light (directly reflected light) refers to the incident angle of the incident light incident on the fixed image on the incident surface formed by the incident light and the normal of the fixed image at the incident point in the reflected light. Reflected light that is reflected and travels at the same reflection angle is referred to (in the following description, “specularly reflected light” is used in the same sense).

Further, a pair of halogen lamps 41A and 41A
The CD sensor 42A, the lamp 41B and the sensor 42B, and the lamp 41C and the sensor 42C may be arranged at opposite positions. Further, as shown in FIG. 6, the halogen lamp 41A is so set that the directions of the incident light and the reflected light are orthogonal to the transport direction (leftward behind the fixing device 40 in FIG. 1).
Any arrangement may be used as long as light can be applied to the fixing test image TA and the like and its regular reflected light can be received, such as the arrangement of the CCD sensor 42A and the like.

However, it is desirable that the incident angle α and the reflection angle β be 25 degrees or more. If the angle is smaller than 25 degrees, the component of the diffused light that wraps around from the periphery becomes large, so that the intensity information of the specularly reflected light cannot be measured accurately, and the arrangement of the halogen lamps 41A to 41C and the CCD sensors 42A to 42C becomes difficult. is there. Further, the incident angle α is more preferably 45 degrees or more. By arranging the halogen lamps 41A to 41C and the CCD sensors 42A to 42C in this way, the fixing test images TA to TC are less susceptible to the influence of the thickness of the fixing test images TA to TC and the lifting of the recording medium S at the time of measurement.
This is because the intensity information of the specularly reflected light can be measured more accurately.

As described above, the halogen lamps 41A to 41C
And the CCD sensors 42A to 42C, the image information detecting unit 43 can detect the glossiness of the regular reflection light (direct reflection light) of the fixing test images TA to TC. That is, the image information detecting unit 43 is provided with the CCD sensor 42A.
To 42C, the intensity IbA to IbC of the reflected light, and the intensity of the incident light (emission intensity) of the halogen lamps 41A to 41C.
By detecting IaA to IaC, the glossiness of the regular reflection light of the fixing test images TA to TC is detected. The reason for detecting the glossiness of the specular reflection light is that the detection range is wide and strong against noise. In addition, the detection of the emission intensities IaA to IaC of the halogen lamps 41A to 41C includes a method of directly measuring the intensities by using a half mirror or the like, and indirectly from the applied voltage, current consumption, power consumption, and the like of the light emitting element. Measurement method.

Next, a brief description will be given of the operation of the copying machine 1 configured as described above when copying is performed. In the copying machine 1, the following processing is performed in the order of yellow (Y), cyan (C), magenta (M), and black (K) reproduction colors. First, the processing of yellow (Y) will be described. The image reading unit 2 detects yellow (Y) of the original image
Read the image data corresponding to. In addition, the surface of the photosensitive drum 30 rotating in the direction of the arrow in FIG. 1 is uniformly charged by the charging charger 31.

Then, a laser control unit 59 described later (FIG. 7)
), The image data read by the image reading unit 2 is input. Then, the laser light is modulated and emitted from the laser light source, and this laser light is scanned in the main scanning direction by the polygon mirror 21, further reflected by the reflection mirror 22, and enters the photosensitive drum 30. As a result, an electrostatic latent image corresponding to the reproduced color of yellow (Y) is formed on the photosensitive drum 30. This electrostatic latent image is developed by the developing device 32Y to become a toner image. This toner image is transferred onto a recording medium S supplied from a paper cassette 44 or a manual feed tray 45 by a transfer charger 33 arranged to face the photosensitive drum 30.

Next, cyan (C), magenta (M),
The processing for black (K) is performed similarly. By these processes, the four color toner images are transferred onto the recording medium S in a superimposed manner. Thereafter, the recording material S to which these toner images have been transferred is heated and pressed in the fixing device 40. As a result, the toner is melted, and the toner image is fixed on the recording medium S to form a full-color image. After the image is fixed, the recording medium is discharged out of the apparatus and stored in the paper discharge tray 46. This completes the copying for one sheet.

Here, a control system of the copying machine 1 for controlling such a copying operation and the like will be described. As shown in the block diagram of FIG. 7, the control circuit of the copying machine 1
4 as the center. The overall control unit 54 also corresponds to an initial image information storage unit, a detection timing determination unit, an image information comparison unit, and an image forming process condition correction unit of the present invention. And the like. The ROM incorporated in the general control unit 54 includes:
Various programs necessary for executing the control of the copying machine 1 and reference data are prepared and stored in advance. Note that test image data for creating a test image, which will be described later, and the like are also stored in the ROM. Further, the RAM is provided with various buffers for temporarily storing numerical values and the like appearing during execution of the arithmetic processing and for reading out the data as needed.

An input / output port of the general control unit 54 includes an IR control unit 51 for controlling the operation of the image reading unit 2 and a fixing unit 4.
A drive control unit 55 for controlling the driving / stopping of the zero and the speed control of the pressure roller 213; a conveyance control unit 56 for controlling the supply of the recording medium; a scanner control unit 57 for controlling the laser beam scanning by the polygon mirror 21; A high-voltage control unit 58 for controlling high voltages such as charging of the photosensitive drum 30, application of a developing bias and a transfer bias, a laser control unit 59 for controlling laser light modulation, an image information detecting unit 43, and a fixing device 4
0 fixing temperature (exactly the surface temperature of the heating roller 212)
Temperature sensor 222 which detects
1 etc. are connected. In addition, the general control unit 54 includes:
A signal is input from the operation panel 53 via the controller 52.

The copying machine 1 is controlled by the general control unit 54 and operates as follows. First, the size and type of the recording medium and other control information are input from the operation panel 53 to the controller 52 by the operator.
Next, when the copy button on the operation panel 53 is pressed, a copy request signal is transmitted, and this signal is transmitted to the controller 5.
2 is received. Then, a print command is output from the controller 52 to the overall control unit 54. In response to this command, the general control unit 54 instructs the IR control unit 51 to start reading an image of a document, and also instructs the transport control unit 56 to start supplying a recording medium. Scan preparation is instructed. Also, a command is output to the high-voltage control unit 58, and the charging of the photosensitive drum 30, the developing bias, and the transfer bias are set, and preparation for image formation is performed. When the reading of the image of the document by the image reading unit 2 is completed, the read image data is input to the laser control unit 59.

Next, the overall control unit 54 controls the controller 5
2 to output a vertical synchronization request signal and wait for reception of a vertical synchronization signal. Then, when the controller 52 outputs the vertical synchronization signal, the laser light is modulated and emitted based on the image data input to the laser control unit 59. As a result, an electrostatic latent image is formed on the photosensitive drum 30 and the developing device 32Y
(32C, 32M, 32K) to form a toner image. This toner image is transferred to a recording medium, and is
The image is fixed by 0 to form a fixed image. At this time, the temperature sensor 222 detects the surface temperature (fixing temperature) of the heating roller 212 of the fixing device 40 and outputs the detection result to the overall control unit 5.
Send to 4.

Here, the correction control for maintaining the image state of the fixed image at the same level as the initial state will be described with reference to the flowchart shown in FIG. The process after S5 shown in this flowchart is executed after a predetermined number of copies have been made. However, when the operator selects the test mode from the operation panel 53, the process is executed by interruption. May be.

First, it is determined whether or not the copying machine 1 is in an initial state (S1). Specifically, it is determined whether or not the sheet passing counter C is zero. Note that this paper passing counter C is
In addition to the initial stage of the product, it is reset to zero by reset processing by a service person. If the sheet passing counter C is zero (S1: YES), the laser control unit 5 shown in FIG.
9, the test image data acquired by the overall control unit 54 from the internal ROM is input, and predetermined fixing test images TA to TC are created by the above procedure (S).
2). Next, the image information detecting unit 43 detects the regular reflection light intensities IbA, IbB, I of the fixing test images TA, TB, TC.
bC and the emission intensities IaA, IaB, IaC of the halogen lamps 41A, 41B, 41C are detected. And
The overall control unit 54 uses each of them to make each fixing test image TA
Calculate the initial glossiness of ~ TC (S3). These initial gloss levels are stored in the overall control unit 54. On the other hand, when the sheet passing counter C is not zero, that is, when the sheet passing counter C is not in the initial state (S1: NO), the process bypasses S2 and S3 and proceeds to S4.

Subsequently, the sheet passing counter C is counted up (S4), and it is determined whether or not the sheet passing counter C has reached "1000", that is, whether or not 1000 copies have been made (step S4). S5). Paper passing counter C is "1000"
(S5: NO), this routine ends once. On the other hand, if the paper passing counter C is "1000"
Is reached (S5: YES), the correction control in S6 and thereafter is executed. First, similarly to S2, the fixing test images TA to TC are created based on the test image data stored in advance in the ROM in the general control unit 54 (S6). Next, in the same manner as in S3, the overall control unit 54 sets each of the fixing test images TA to T based on the detection result of the image information detecting unit 43.
The gloss of C is calculated (S7).

Next, the overall control unit 54 calculates a gloss difference between the initial glossiness of the fixing test image TA calculated in S3 and the glossiness of the fixing test image TA calculated in S7 (S8). The rank of the gloss difference is determined from the calculation result, and the overall control unit 54 reads the correction value of the charging voltage value of the power supply 311A according to the rank (S
9). The rank of the gloss difference is shown in Table 1 according to the gloss difference.
Are classified into seven levels (A to G ranks) as shown in Fig. 7 and the case where there is little difference from the initial gloss level is set as a standard (D rank), and the cases where the initial gloss level is higher and lower are classified into three levels. Have been.

[0062]

[Table 1]

Similarly, the overall control unit 54 calculates the gloss difference for the fixing test images TB and TC (S1).
0, S12) and power supplies 311B, 311 according to the ranks in Table 1.
The correction value of the charging voltage value of 11C is read (S1
1, S13). Then, based on the correction values read in S9, S11, and S13, each power supply 311
A, 311B, charge wire 312 by 311C
The voltage values applied to A, 312B and 312C are corrected (S14). Thus, each of the chargers 31A to 31A-3
The amount of charge applied to the photosensitive drum 30 by 1C changes in the axial direction. For this reason, the amount of toner adhering to the photosensitive drum 30 can be changed in the axial direction. Then, S9 and S1 until the next 1000th sheet.
Based on the correction values of the charging voltage read in Steps S1 and S13, charges are applied to the photosensitive drum 30 by the charging chargers 31A to 31C.

By the way, when the fixing condition is constant, when the amount of toner adhered is large, the surface of the image is easily smoothed, so that the glossiness is high. Therefore, it is known that the glossiness decreases. Therefore, by correcting the charging condition without correcting the fixing condition, the glossiness can be made closer to a predetermined value. Specifically, when the glossiness is higher than the initial glossiness, the toner adhesion amount may be reduced, that is, the charging voltage value may be reduced. Conversely, when the glossiness is lower than the initial glossiness, the toner adhesion amount, that is, the charging voltage value may be increased.

Thereafter, the above processing is repeated, and every time 1000 copies are made, the correction value of the charging voltage value for each of the charging chargers 31A to 31C is updated so that the glossiness approaches the initial glossiness. The charge is applied to the photosensitive drum 30 by the updated correction value up to 1000 sheets. As a result, the image state of the fixed image is maintained at the same level as the initial state.

As described above in detail, according to the copying machine 1 of the first embodiment, predetermined fixing test images TA to TC are created on the recording medium S in the initial state. Then, the overall control unit 54 sets the image information detection unit 4
Based on the reflected light intensity and the like obtained in step 3, each fixing test image TA
To TC and calculate and store them.
Next, predetermined fixing test images TA to TC are created on the recording medium S periodically at a predetermined timing. And
The overall control unit 54 calculates the glossiness of each of the fixing test images TA to TC based on the reflected light intensity and the like obtained by the image information detection unit 43, and compares the calculated glossiness with the initial glossiness. Thereafter, the overall control unit 54 corrects the charging voltage values in the first to third charging chargers 31A to 31C based on the comparison result. Accordingly, if the fixing condition is constant because the toner adhesion amount changes in the axial direction of the photosensitive drum 30, the glossiness of the fixed image changes in a direction orthogonal to the recording medium conveyance direction and is substantially equal to the initial glossiness. Become. That is, the image state in the initial state is maintained.

(Second Embodiment) Next, a second embodiment will be described. The copying machine according to the second embodiment has substantially the same basic configuration as that of the copying machine 1 according to the first embodiment. However, instead of correcting the charging voltage value of the charging charger, a developing device is used. The difference is that the developing bias voltage value applied to the provided developing roller is corrected. That is, the overall control unit 54 issues an instruction to the high voltage control unit 58 to correct the developing bias voltage values in the developing units 320Y to 320K. Accordingly, the configuration of the developing device is also different from that of the first embodiment. The configuration of the developing device will be described with reference to FIGS. In addition,
Descriptions of the same components as those in the first embodiment, copy operations, and the like are omitted, and the same components are denoted by the same reference numerals. Further, the developing devices 320Y, 320M, 320
Since the configurations of C and 320K are all the same, the color codes Y, M, C and K are omitted as appropriate in the following description.

As shown in FIG. 9, the developing device 320 of the present embodiment includes three developing devices, that is, a first developing device 323A, a second developing device 323B, and a third developing device 323C. Then, as shown in FIG. 10, the first developing device 323A and the third developing device 323C are provided at the same angular position in the circumferential direction of the photosensitive drum 30, and the second developing device 32
3B is provided at an angular position different from the first developing device 323A and the third developing device 323C (an angular position slightly advanced in the rotation direction of the photosensitive drum 30). These developing devices 32
3A to 323C are developing rollers 322A to 322C, respectively.
22C, and these developing rollers 322A to 322C
Power supplies 321A to 321C for applying a developing bias voltage to
have. These power supplies 321A to 321C are connected to the high voltage control unit 58 (see FIG. 7).
By the high-pressure controller 58, the first developing device 323A, the second developing device 323B, and the third developing device 323C can supply toner to the photosensitive drum 30 under different developing conditions. Note that a fixing test image TA is created in an area where the first developing device 323A supplies toner to the photosensitive drum 30. In a similar relationship, a fixing test image TB is created in a region where the second developing device 323B supplies toner to the photosensitive drum 30, and the third test image TB is created.
A fixing test image TC is created in an area where the developing device 323C applies toner to the photosensitive drum 30.

In the copying machine having the above-described configuration, the correction control for maintaining the image state of the fixed image at the same level as the initial state, that is, the correction control of the developing bias voltage value, is performed in the first embodiment. This is performed in the same manner as the voltage value correction control. That is, the overall control unit 54
The initial glossiness of each of the fixing test images TA to TC is calculated and stored based on the detection result of the image information detection unit 43. Each time 1000 copies are made, the fixing test images TA to TC are created, and the overall control unit 54 sets each fixing test image T
The glossiness of A to TC is calculated. Next, a gloss difference between the gloss and the initial gloss is calculated. The rank of the gloss difference is determined by the calculation result, and the overall control unit 54 reads the correction value of the developing bias voltage value corresponding to the rank. The rank of the gloss difference is divided into seven stages (A to G ranks) as shown in Table 2 according to the gloss difference.
Standard when there is almost no difference from the initial gloss (D rank)
Are classified into three levels for the cases where the glossiness is higher than the initial glossiness and the cases where the glossiness is lower than the initial glossiness.

[0070]

[Table 2]

The first developing unit 323A and the second developing unit 323A
The developing bias voltage values in the developing device 323B and the third developing device 323C are corrected. As a result, the amount of toner applied to the photosensitive drum 30 by each of the developing devices 323A to 323C changes. For this reason, the amount of toner adhering to the photosensitive drum 30 can be changed in the axial direction. Then, until the next 1000th sheet, each of the chargers 31A to 31A is set based on the correction value of the developing bias voltage value.
Development by 31C is performed.

As described above, when the fixing condition is constant, the glossiness increases when the toner adhesion amount is large, and conversely, the glossiness decreases when the toner adhesion amount is small. Therefore, by correcting the developing conditions without correcting the fixing conditions, the glossiness can be made closer to a predetermined value. Specifically, if the glossiness is higher than the initial glossiness,
What is necessary is just to reduce the toner adhesion amount, that is, to reduce the developing bias voltage value. Conversely, when the glossiness is lower than the initial glossiness, the toner adhesion amount, that is, the developing bias voltage value may be increased.

Thereafter, the above processing is repeated, and every time 1000 copies are made, the correction values of the developing bias voltage values in the developing units 323A to 323C are updated so that the glossiness approaches the initial glossiness. Up to 1000 sheets are developed with the updated correction value. This allows
The image state of the fixed image is maintained at the same level as the initial state.

As described above, according to the copying machine of the second embodiment, predetermined fixing test images TA to TC are created on the recording medium S in the initial state.
The overall control unit 54 calculates the initial glossiness of each of the fixing test images TA to TC based on the reflected light intensity and the like obtained by the image information detection unit 43, and stores the calculated initial glossiness. Then
Periodically, predetermined fixing test images TA to TC are created on the recording medium S at predetermined timing. Then, the overall control unit 54 calculates the glossiness of each of the fixing test images TA to TC based on the reflected light intensity and the like obtained by the image information detection unit 43, and compares the calculated glossiness with the initial glossiness. Thereafter, based on the result of the comparison, the overall control unit 54 sets the first to third
The developing bias voltage values at 23A to 323C are respectively corrected. Accordingly, if the fixing condition is constant because the toner adhesion amount changes in the axial direction of the photosensitive drum 30, the glossiness of the fixed image changes in a direction orthogonal to the recording medium conveyance direction and is substantially equal to the initial glossiness. Become. That is, the image state in the initial state is maintained.

(Third Embodiment) Next, a third embodiment will be described. The copying machine according to the third embodiment has substantially the same basic configuration as that of the copying machine 1 according to the first embodiment. The difference is that the transfer voltage value is corrected. That is, the overall control unit 54
An instruction is issued to the high voltage control unit 58 to correct the transfer voltage value in the transfer charger 330. Accordingly, the configuration of the transfer charger is also different from that of the first embodiment. The structure of the transfer charger is shown in FIG.
1 and FIG. The description of the same components as those in the first embodiment, the copy operation, and the like is omitted, and the same components are denoted by the same reference numerals.

The transfer charger 330 according to the present embodiment
As shown in FIG. 11, three transfer chargers, that is, a first transfer charger 33A, a second transfer charger 33B,
And a third transfer charger 33C.
Then, as shown in FIG. 12, the first transfer charger 33
A and the third transfer charger 33C are provided at the same angular position in the circumferential direction of the photosensitive drum 30, and the second transfer charger 33B is at an angular position different from the first transfer charger 33A and the third transfer charger 33C (slightly different from the photosensitive drum 33C). 30 (an angular position advanced in a direction opposite to the rotation direction). These transfer chargers 33A to 33C are:
Power supply 331A-331C and charge wire 3 respectively
32A to 332C, and power supplies 331A to 33
1C are each connected to the high-voltage control unit 58 (see FIG. 7). The high-voltage controller 58 allows the first transfer charger 33A, the second transfer charger 33B, and the third transfer charger 33C to transfer the toner image formed on the photosensitive drum 30 to the recording medium under different transfer conditions. Has become. The fixing test image TA is created in an area where the first transfer charger 33A can transfer the toner image on the photosensitive drum 30. In a similar relationship, the second transfer charger 33B is connected to the photosensitive drum 3
Fixing test image TB in the area where toner image on 0 can be transferred
Is formed, and a fixing test image T is formed in an area where the third transfer charger 33C can transfer the toner image on the photosensitive drum 30.
C is created.

In the copier having the above-described configuration, the correction control for maintaining the image state of the fixed image at the same level as the initial state, that is, the correction control of the transfer voltage value, is performed in the same manner as in the first embodiment. This is performed in the same manner as the value correction control. That is, based on the detection result of the image information detection unit 43, the overall control unit 54 sets each of the fixing test images TA to
The initial gloss of TC is calculated and stored. When the number of copies reaches 1000, the fixing test image T
A to TC are created, and each of the fixing test images TA to TC is generated by the overall control unit 54 based on the detection result of the image information detecting unit 43.
The glossiness of TC is calculated. Next, a gloss difference between the gloss and the initial gloss is calculated. The rank of the gloss difference is determined based on the calculation result, and the overall control unit 54 reads the correction value of the transfer voltage value corresponding to the rank. The rank of the glossiness difference is divided into seven stages (A to G ranks) as shown in Table 3 according to the glossiness difference, and a case where there is almost no difference from the initial glossiness is defined as a standard (D rank). The cases where the gloss is higher than the gloss and the case where the gloss is lower are classified into three levels.

[0078]

[Table 3]

Then, based on the respective correction values read by the general control unit 54, the first transfer charger 33
A, the transfer voltage values in the second transfer charger 33B and the third transfer charger 33C are corrected. As a result, each of the transfer chargers 33A to 33C is
The amount of toner to be moved from above 0 to the recording medium S changes.
For this reason, the amount of toner adhering to the recording medium S can be changed in a direction orthogonal to the recording medium conveyance direction. Then, up to the next 1000 sheets, transfer is performed by each of the transfer chargers 33A to 33C based on the correction value of the transfer voltage value.

As described above, when the fixing condition is constant, the glossiness increases when the toner adhesion amount is large, and conversely, the glossiness decreases when the toner adhesion amount is small. Therefore, by correcting the transfer condition without correcting the fixing condition, the glossiness can be made closer to a predetermined value. Specifically, if the glossiness is higher than the initial glossiness,
What is necessary is just to reduce the toner adhesion amount, that is, to reduce the transfer voltage value. Conversely, when the glossiness becomes lower than the initial glossiness, the toner adhesion amount may be increased, that is, the transfer voltage value may be increased.

Thereafter, the above processing is repeated, and every time 1000 copies are made, the correction value of the transfer voltage value in the transfer chargers 33A to 33C is updated so that the glossiness approaches the initial glossiness, and the next 1000 copies are made. Transfer is performed with the updated correction value for the sheets. As a result, the image state of the fixed image is maintained at the same level as the initial state.

As described above, according to the copying machine of the third embodiment, predetermined fixing test images TA to TC are created on the recording medium S in the initial state.
The overall control unit 54 calculates the initial glossiness of each of the fixing test images TA to TC based on the reflected light intensity and the like obtained by the image information detection unit 43, and stores the calculated initial glossiness. Then
Periodically, predetermined fixing test images TA to TC are created on the recording medium S at predetermined timing. Then, the overall control unit 54 calculates the glossiness of each of the fixing test images TA to TC based on the reflected light intensity and the like obtained by the image information detection unit 43, and compares the calculated glossiness with the initial glossiness. Thereafter, the overall control unit 54 corrects the transfer voltage values in the first to third transfer chargers 33A to 33C based on the comparison result. As a result, the amount of toner adhering to the recording medium S changes in the axial direction of the photoconductor drum 30 (a direction orthogonal to the recording medium conveyance direction).
The glossiness of the fixed image changes in a direction orthogonal to the recording medium conveyance direction and becomes substantially equal to the initial glossiness. That is, the image state in the initial state is maintained.

When a constant-voltage-controlled transfer charger is used, a similar effect can be obtained by correcting the transfer current value.

(Fourth Embodiment) Next, a fourth embodiment will be described. The copying machine according to the fourth embodiment has substantially the same basic configuration as that of the copying machine 1 according to the first embodiment. The difference is that the fixing temperature is corrected. That is, the overall control unit 54 corrects the control temperature of the heater lamp in the fixing device. Accordingly, the configuration of the fixing device is also different from that of the first embodiment. The configuration of the fixing device will be described with reference to FIG. The description of the same components as those in the first embodiment, the copy operation, and the like is omitted, and the same components are denoted by the same reference numerals.

As shown in FIG. 13, the fixing device 400 of this embodiment includes a heating roller 412 and a pressing roller 413.
Is provided with three heater lamps, that is, a first heater lamp 421A, a second heater lamp 421B, and a third heater lamp 421C. These heater lamps 421A to 421C are connected to the overall control unit 54, and the first heater lamp 421A and the second heater lamp 42
1B and the third heater lamp 421C can be set at different temperatures. Accordingly, when the toner image transferred onto the recording medium S is fixed on the recording medium S, the control temperatures of the heater lamps 421A to 421C can be set separately. Therefore, the fixing temperature in the fixing device 400 can be corrected in the axial direction of the heating roller 412.

In the copying machine having the above-described configuration, the correction control for maintaining the image state of the fixed image at the same level as the initial state, that is, the correction control of the fixing temperature is performed according to the charging voltage value in the first embodiment. Is performed in the same manner as in the correction control. That is, based on the detection result of the image information detection unit 43, the overall control unit 54 sets each of the fixing test images TA to T
The initial glossiness of C is calculated and stored. When the number of copies reaches 1000, the fixing test image TA
To TC are created, and each of the fixing test images TA to T is determined by the overall control unit 54 based on the detection result of the image information detecting unit 43.
The glossiness of C is calculated. Next, a gloss difference between the gloss and the initial gloss is calculated. The rank of the gloss difference is determined based on the calculation result, and the overall control unit 54 reads the correction value of the fixing temperature corresponding to the rank. In addition,
The rank of the gloss difference is divided into seven levels (A to G ranks) as shown in Table 4 according to the gloss difference, and the initial gloss level is defined as a standard (D rank) when there is almost no difference from the initial gloss level. There are three ranks for each of the cases where there are more and less cases.

[0087]

[Table 4]

Then, based on the respective correction values read by the general control section 54, the first heater lamp 421
A, the control temperatures of the second heater lamp 421B and the third heater lamp 421C are changed. This allows
The fixing temperature changes in a direction perpendicular to the recording medium conveyance direction. For this reason, the glossiness of the fixed image on the recording medium S can be changed in a direction orthogonal to the recording medium conveyance direction. Until the next 1000th sheet, fixing by the fixing device 400 is performed based on the correction value of the fixing temperature value.

Thereafter, the above process is repeated, and every time 1000 copies are made, the fixing temperature of the fixing device 400 (heater lamp 4) is set so that the glossiness approaches the initial glossiness.
21A to 421C (control temperature values) are updated,
Up to the next 1000 sheets, fixing is performed with this updated correction value. As a result, the image state of the fixed image is maintained at the same level as the initial state.

As described above in detail, according to the copying machine of the fourth embodiment, predetermined fixing test images TA to TC are created on the recording medium S in the initial state.
Then, based on the reflected light intensity and the like obtained by the image information detection unit 43, the overall control unit 54 sets each of the fixing test images TA to T
The initial glossiness of C is calculated and stored. Next, predetermined fixing test images TA to TC are created on the recording medium S periodically at a predetermined timing. Then, the overall control unit 54 calculates the glossiness of each of the fixing test images TA to TC based on the reflected light intensity and the like obtained by the image information detection unit 43, and compares the calculated glossiness with the initial glossiness. Thereafter, the overall control unit 54 corrects the fixing temperature by changing the control temperature values of the first to third heater lamps 421A to 421C based on the comparison result. As a result, the glossiness of the fixed image changes in a direction orthogonal to the recording medium conveyance direction and becomes substantially equal to the initial glossiness. That is, the image state in the initial state is maintained.

(Fifth Embodiment) Next, a fifth embodiment will be described. The configuration of the copying machine according to the fifth embodiment is substantially the same as that of the copying machine 1 according to the first embodiment, but the fixing test image creation position is different. More specifically, as shown in FIG. 14, the fixing test images T1 and T2 are created in the transport direction of the recording medium. Another difference is that the image information detecting section 63 for detecting the reflected light intensity information of the fixing test image includes only one set of the halogen lamp 41 and the CCD sensor 42. This makes it possible to grasp the difference in glossiness from the initial state in the recording medium conveyance direction. Another difference is that an undivided charger is used as in the first embodiment.

The correction control for maintaining the image state of the fixed image at the same level as the initial state in the copying machine having the above configuration will be described with reference to the flowchart shown in FIG. The processing after S25 shown in this flowchart is executed after the predetermined number of copies have been made. However, the processing is executed by interruption when the operator selects the test mode from the operation panel 53 or the like. May be.

First, it is determined whether the copying machine is in the initial state (S21). Specifically, it is determined whether or not the sheet passing counter C is zero. Note that this paper passing counter C is
In addition to the initial stage of the product, it is reset to zero by reset processing by a service person. If the sheet passing counter C is zero (S21: YES), the test image data stored in the ROM in the general control unit 54 is input to the laser control unit 59 shown in FIG. Fixing test images T1 and T2 are created (S22). Next, the image information detecting unit 63 detects the regular reflection light intensities Ib1 and Ib2 of the fixing test images T1 and T2 and the light emission intensity Ia of the halogen lamp 41. Then, the overall control unit 54 calculates the initial glossiness of each of the fixing test images T1 and T2 using these (S23). These initial gloss levels are stored in the overall control unit 54. On the other hand, if the sheet passing counter C is not zero, that is, if it is not in the initial state (S21: NO),
The process proceeds to S24 bypassing S22 and S23.

Subsequently, the sheet passing counter C is counted up (S24), and thereafter, the sheet passing counter C is set to "10".
It is determined whether or not “00” or more (S25). If the paper passing counter is equal to or greater than "1000" (S25:
YES), and proceed to S26. On the other hand, if the paper passing counter C is "1"
If it is less than "000" (S25: NO), this routine ends once.

Then, in S26, the sheet passing counter C sets C =
It is determined whether or not 1000 × n is satisfied. Note that n is a natural number. When the sheet passing counter C reaches “1000” (hereinafter, 2000, 3000,...) (S2
6: YES), the reading of the correction values after S27 is executed. First, in the same manner as in S22, the R
Fixing test images T1 and T2 are created based on the test image data stored in the OM in advance (S27). Next, in the same manner as in S23, the overall control unit 54 sets each of the fixing test images T1,
The gloss of T2 is calculated (S28).

Subsequently, the overall control unit 54 calculates a gloss difference between the initial glossiness of the fixing test image T1 calculated and stored in S23 and the glossiness of the fixing test image T1 calculated in S28 ( S29). The rank of the gloss difference is determined from the calculation result, and the overall control unit 54 reads the correction value V1 of the charging voltage value for the fixing test image T1 corresponding to the rank (S30). The rank of the glossiness difference is divided into seven stages (A to G ranks) as shown in Table 1 according to the glossiness difference, and the initial glossiness is defined as a standard (D rank) when there is almost no difference from the initial glossiness. The ranks are classified into three levels for each of the cases where the number is higher than the degree and the case where the number is lower than the degree.

Similarly, the overall control unit 54 calculates a gloss difference also for the fixing test image T2 (S31), and reads the correction value V2 of the charging voltage value for the fixing test image T2 according to the rank in Table 1. (S32). Thereafter, this routine ends once.

On the other hand, at S26, the sheet passing counter C is set to C = 1.
000 × n, that is, when the sheet passing counter C is “1001 to 1999” (hereinafter, 2001)
２９2999, 3001 to 3999,...)
26: NO), the correction of the charging voltage value after S32 is executed based on the correction values V1 and V2 of the charging voltage value read in S30 and S32, respectively.

To correct the charged voltage value, first, the correction timer t is reset, and the timer starts counting (S3).
3). In the present embodiment, the correction timer t is reset 0.5 seconds after the start of the application of the charging voltage. Then, the charging voltage value V (t) is calculated by the following equation, and the photosensitive drum 30 is charged based on the charging voltage value V (t) (S34). V (t) = ((V2−V1) /2.4) × t + V1 + Vs where V1 and V2 are charging voltage correction values (including a sign),
Vs is a standard charging voltage value.

Thereafter, the correction timer t is counted up every 0.1 seconds (S35), and it is determined whether 2.4 seconds have elapsed from the start of the time measurement (S36). If 2.4 seconds have not elapsed (S36: NO), the process returns to S34 and returns to S
The processing between 34 and S36 is repeatedly performed. By this processing, the charging voltage value V (t) becomes V (0) = V1 + Vs immediately after the correction is started, and thereafter, the charging voltage value V (t) is calculated every 0.1 second, and finally the charging voltage value V (t) is calculated. Immediately after 2.4 seconds have passed, V (2.4) = V2 + Vs.
As a result, the amount of charge applied to the photoconductor drum 30 by the charging charger changes in the circumferential direction of the photoconductor drum 30 (recording material conveyance direction). For this reason, since the amount of toner adhering to the photosensitive drum 30 changes in the circumferential direction, the amount of toner adhering on the recording medium can be changed in the recording medium transport direction. Therefore, if the fixing condition is constant, the glossiness can be changed to a predetermined value. Then, when 2.4 seconds have elapsed from the start of the timing of the correction timer (S36: YE
S), this routine ends once.

Note that the time when the correction timer t finishes measuring the time is 2.4 seconds in the present embodiment because the recording medium S
A4 size recording medium S whose transport speed is 120 mm / s
Is passed in the vertical direction to generate fixing test images T1 and T2 at an interval of 285 mm. That is, from the measurement of the glossiness of the fixing test image T1 to the measurement of the glossiness of the fixing test image T2, 285/12
This is because 0 = 2.4 (seconds) is required. Therefore, the time when the counting of the correction timer t ends is determined by the conveyance speed of the recording medium and the interval between the fixing test images T1 and T2.

Thereafter, the above processing is repeated, and every time 1000 copies are made, new correction values V1 and V2 are read so that the glossiness approaches the initial glossiness, and the charging voltage value V (t) is calculated. The correction value is updated, and charge is applied to the photosensitive drum 30 by the updated correction value for the next 1000 sheets. As a result, the image state of the fixed image is
In the recording medium conveyance direction, it is maintained at the same level as the initial state.

Here, the correction control of the charging voltage value shown in FIG. 15 will be described with specific numerical values. First, in the initial state of the copying machine (S21: YES), fixing test images T1 and T2 are created (S22). Then, the overall control unit 54 calculates and stores the initial glossiness of each of the fixing test images T1 and T2 (S23). At this time, as shown in FIG. 16, the initial glossiness of the fixing test image T1 is “65”,
It is assumed that the initial glossiness of T2 is stored as “70”.

Thereafter, when the sheet passing counter C reaches "1000" (S25: YES, S26: YES), the fixing test images T1 and T2 are created again (S27), and the glossiness is determined by the overall control unit 54. Is calculated (S2
8). At this time, as shown in FIG. 17, the glossiness of the fixing test image T1 is “75”, and the initial glossiness of T2 is “60”.
Is calculated. Next, in the overall control unit 54, the glossiness difference in the fixing test image T1 is 10 (=
75-65), and the rank of the gloss difference is determined to be “C” (S29). Then, in S30, the correction value V1 (= + 50 V) of the charging voltage value corresponding to the rank is read. Similarly, for the fixing test image T2, the gloss difference is calculated as -10 (= 60-70),
It is determined that the rank of the gloss difference is “E” (S3
1). Then, in S32, the correction value V2 (= −100 V) of the charging voltage value corresponding to the rank is read, and this routine ends once.

Subsequently, the process of S21 is executed again.
At this time, since the sheet passing counter C is "1000",
NO is determined in S21. Therefore, the process proceeds to S24, where the count-up is performed, and the sheet passing counter C becomes "10
01 ". Therefore, YES is determined in S25 and S
Proceed to 26. Then, in S26, NO is determined and S3
Proceeding to 3, the correction of the charging voltage value is executed. In this correction, as shown in FIG. 18, when the sensor detects the leading end of the recording medium S, first, a charging voltage of -600 V (standard value) is applied. About 0.5 seconds later, the correction timer t is reset, and the timer starts counting (S33). Then, the charging voltage value V (t) is calculated based on the correction values V1 and V2, and the calculated corrected charging voltage value V (t) is applied to the charging charger (S34). The corrected charging voltage value V (t) changes every 2.4 seconds to 2.4 seconds (the actual control value changes stepwise). That is, at t = 0, V (0) = − 600 + 50 = −500
V, which gradually changes (increases in the negative direction) every 0.1 second, and finally, at t = 2.4, V (2.4) =
-600-100 = -700V.

A developing bias voltage is applied about 0.6 seconds after the detection of the leading end of the recording medium S, and a transfer voltage is applied about 0.8 seconds after the detection of the leading end of the recording medium S.
An unfixed image is created on the recording medium S. After that, the unfixed image created on the recording medium S is fixed by the fixing device 40.

By applying such a charging voltage value to the charging charger, the amount of toner adhering from the front end to the center of the recording medium S decreases, and the amount of toner adhering from the center to the rear end increases. For this reason, if the fixing conditions are constant, the gloss from the front end to the vicinity of the center of the recording medium S decreases, and the gloss from the vicinity of the center to the rear end increases. As a result, the glossiness of the 1001th fixed image is substantially equal to the glossiness shown in FIG. 17, so that the initial image state can be maintained.

After that, until the 1999th copy, the charging voltage value is corrected as shown in FIG. 18, so that an image state substantially equal to the initial state is maintained. And 2000
In the first copy, fixing test images T1 and T2 are created again, and new correction values V1 and V2 are read and 299
Up to the ninth copy, the charging voltage value V (t) based on the new correction value is applied. Thereafter, the charging voltage value V (t) corrected for every 1000 sheets is updated, so that the same image state as the initial state can always be maintained.

As described above in detail, according to the copying machine of the fifth embodiment, predetermined fixing test images T1 and T2 are formed on the recording medium S in the initial state.
Next, the overall control unit 54 calculates the initial glossiness of each of the fixing test images T1 and T2 based on the reflected light intensity and the like obtained by the image information detection unit 63, and stores it. Then
Periodically, predetermined fixing test images T1 and T2 are created on the recording medium S at a predetermined timing. Then, the overall control unit 54 calculates the glossiness of each of the fixing test images T1 and T2 based on the reflected light intensity and the like obtained by the image information detection unit 63, and compares the calculated glossiness with the initial glossiness. Thereafter, the overall control unit 54 corrects the charging voltage value of the charging charger based on the comparison result. As a result, the amount of toner adhered in the recording medium conveyance direction can be changed, so that the glossiness can be made substantially equal to the initial glossiness if the fixing condition is constant. That is, the image state in the initial state is maintained.

(Sixth Embodiment) Next, a sixth embodiment will be described. The copying machine according to the sixth embodiment has substantially the same basic configuration as the copying machine according to the fifth embodiment, but is provided in a developing device instead of correcting the charging voltage value of the charging charger. The difference is that the developing bias voltage value applied to the developing roller is corrected.

That is, in the copying machine of the present embodiment, the correction control for maintaining the image state of the fixed image at the same level as the initial state, that is, the correction control of the developing bias voltage value, is the same as that of the fifth embodiment. It is performed in the same manner as the voltage value correction control. First, based on the detection result of the image information detecting unit 43, the overall control unit 54 sets each fixing test image T
1 and T2 are calculated and stored. And
When the number of copies reaches 1000, the fixing test images T1 and T2 are created again, and the overall control unit 54 calculates the glossiness of each fixing test image T1 and T2 based on the detection result of the image information detecting unit 43. You. Next, a gloss difference between the gloss and the initial gloss is calculated. Based on the calculation result, the rank of the gloss difference is determined, and the overall control unit 54 reads a correction value according to the rank (see Table 2), and based on this, sets the developing bias voltage value to 0.1.
Correct for 4 seconds. Thus, the amount of toner applied to the photosensitive drum 30 can be changed in the circumferential direction of the photosensitive drum 30 (recording material conveyance direction). That is, the amount of toner adhered on the recording medium S can be changed in the recording medium conveyance direction.

Thereafter, the above processing is repeated, and every time 1000 copies are made, a new correction value is read and the correction value of the developing bias voltage value is updated so that the glossiness approaches the initial glossiness. Development is performed with the updated developing bias voltage value until the next 1000 sheets. As a result, the image state of the fixed image is maintained at the same level as the initial state in the recording medium conveyance direction.

As described above in detail, according to the copying machine of the sixth embodiment, predetermined fixing test images T1 and T2 are created on the recording medium S in the initial state.
Next, the overall control unit 54 calculates the initial glossiness of each of the fixing test images T1 and T2 based on the reflected light intensity and the like obtained by the image information detection unit 43 and stores the calculated initial glossiness. Then
Predetermined fixing test images T1 and T2 are created again on the recording medium S periodically at a predetermined timing. Then, the overall control unit 54 calculates the glossiness of each of the fixing test images T1 and T2 based on the reflected light intensity and the like obtained by the image information detection unit 43, and compares the calculated glossiness with the initial glossiness. Thereafter, the overall control unit 54 corrects the developing bias voltage value based on the comparison result. As a result, the amount of toner adhered in the recording medium conveyance direction can be changed, so that the glossiness can be made substantially equal to the initial glossiness if the fixing condition is constant. That is, the image state in the initial state is maintained.

(Seventh Embodiment) Finally, a seventh embodiment will be described. The copying machine according to the seventh embodiment has substantially the same basic configuration as that of the copying machine according to the fifth embodiment. The difference is that the voltage value is corrected.

That is, in the copying machine of the present embodiment, the correction control for maintaining the image state of the fixed image at the same level as the initial state, that is, the correction control of the transfer voltage value, is the same as the charging voltage in the fifth embodiment. This is performed in the same manner as the value correction control. First, based on the detection result of the image information detecting unit 43, the overall control unit 54 sets each of the fixing test images T1, T2.
Is calculated and stored. Then, when the number of copies reaches 1000, the fixing test images T1,
T2 is created again, and each fixing test image T1, T1,
The glossiness of T2 is calculated. Next, a gloss difference between the gloss and the initial gloss is calculated. Based on the calculation result, the rank of the gloss difference is determined, and the overall control unit 54 reads a correction value corresponding to the rank (see Table 3), and based on this, the transfer voltage value is changed every 0.1 second for 2.4 seconds. to correct.
Thus, the amount of toner moving from the photosensitive drum 30 onto the recording medium S can be changed in the recording medium transport direction.

Thereafter, the above-described processing is repeated, and every time 1000 copies are made, a new correction value is read and the correction value of the transfer voltage value is updated so that the glossiness approaches the initial glossiness. The transfer is performed with the updated transfer voltage value up to 1000 sheets. As a result, the image state of the fixed image is maintained at the same level as the initial state in the recording medium conveyance direction.

As described above, according to the copying machine of the seventh embodiment, predetermined fixing test images T1 and T2 are formed on the recording medium S in the initial state.
Next, the overall control unit 54 calculates the initial glossiness of each of the fixing test images T1 and T2 based on the reflected light intensity and the like obtained by the image information detection unit 43 and stores the calculated initial glossiness. Then
Predetermined fixing test images T1 and T2 are created again on the recording medium S periodically at a predetermined timing. Then, the overall control unit 54 calculates the glossiness of each of the fixing test images T1 and T2 based on the reflected light intensity and the like obtained by the image information detection unit 43, and compares the calculated glossiness with the initial glossiness. Thereafter, the overall control unit 54 corrects the transfer voltage value based on the comparison result. As a result, the amount of toner adhered in the recording medium conveyance direction can be changed, so that the glossiness can be made substantially equal to the initial glossiness if the fixing condition is constant. That is, the image state in the initial state is maintained.

When a constant-voltage-controlled transfer charger is used, a similar effect can be obtained by correcting the transfer current value.

The above-described first to seventh embodiments are merely examples, and do not limit the present invention in any way. Various improvements and modifications can be made without departing from the gist of the present invention. Of course. For example, in the above-described embodiments (the fifth to seventh embodiments) in which the process conditions are corrected in the recording medium conveyance direction, the correction of the process conditions (charging, development, and transfer) in the image forming unit is performed. Although exemplified, the same effect can be obtained by correcting the process condition (fixing speed) in the fixing unit.

Further, in the above embodiment, the difference in glossiness is detected by measuring the intensity of reflected light of the fixed image. However, the difference in transmittance may be detected by measuring the intensity of transmitted light. In this case, the rank and the correction value of the transmittance difference may be those shown in Table 5.

[0121]

[Table 5]

Further, if the light emission intensity of the halogen lamp is always kept constant, the process conditions can be corrected by the image forming process condition changing means based on the intensity information of the reflected light without obtaining the reflectance and glossiness of the fixed image. You can do it too. Further, by detecting a color shift (a shift in lightness, hue, and saturation) of the fixing test image, the process conditions in the image forming process condition changing means can be similarly corrected.

Further, in the above-described embodiment, the fixing means of the roller fixing type is exemplified. However, the fixing means is not limited to this and may be of the belt fixing type. Further, an example in which the present invention is applied to a copying machine has been described. However, the present invention can be applied to any apparatus having an image creating unit and a fixing unit, such as a printer such as a page printer and a facsimile. Furthermore, the test image data for creating the fixing test image can be obtained from outside through an input / output port or the like instead of from a memory or the like stored in advance. Alternatively, it can be obtained from the image reading unit 2 using a test chart or the like on which a test pattern is printed in advance.

[0124]

As described above, according to the image forming apparatus of the present invention, at least the position of the recording medium in the direction orthogonal to the recording medium conveyance direction or in the recording medium conveyance direction is different by the image information comparing means. Initial image information in an initial state of two or more fixing test images is compared with image information detected at a predetermined timing.
Then, the image forming process condition correcting means corrects the process conditions based on the comparison result of the image information comparing means so that the image state approaches the initial state. Thereby, the image state in the initial stage of the product is maintained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a copying machine according to a first embodiment.

FIG. 2 is a perspective view showing a configuration of a charging charger in the copying machine of FIG.

FIG. 3 is a side view of the charging charger shown in FIG. 2;

FIG. 4 is a sectional view showing a configuration of a fixing device in the copying machine of FIG.

FIG. 5 is a perspective view illustrating a configuration of an image information detection unit in the copying machine of FIG. 1;

FIG. 6 is a perspective view illustrating another configuration of the image information detection unit.

FIG. 7 is a block diagram showing a part of a control circuit of the copying machine shown in FIG. 1;

FIG. 8 is a flowchart illustrating control for correcting a charging condition.

FIG. 9 is a perspective view illustrating a configuration of a developing device according to a second embodiment.

FIG. 10 is a side view of the developing device of FIG. 9;

FIG. 11 is a perspective view illustrating a configuration of a transfer charger according to a third embodiment.

FIG. 12 is a side view of the developing device of FIG. 11;

FIG. 13 is a cross-sectional view illustrating a configuration of a fixing device according to a fourth embodiment.

FIG. 14 is an explanatory diagram for describing a method of detecting image information in an image information detection unit in a copying machine according to a fifth embodiment.

FIG. 15 is a flowchart illustrating control for correcting a charging condition.

FIG. 16 is an explanatory diagram for describing an example of an initial glossiness stored in the overall control unit.

FIG. 17 is an explanatory diagram illustrating an example of glossiness measured when the number of copies reaches 1,000.

FIG. 18 is a timing chart showing how the charging voltage value, the transfer voltage value, and the developing bias voltage value change.

[Explanation of symbols]

 5 Image Processing Unit 30 Photoconductor Drum 31 Charger 31A to 31C First to Third Charger 312A to 312C Charge Wire 32Y, 32C, 32M, 32K Developing Device 33 Transfer Charger 34 Transfer Drum 40 Fixing Device 41A to 41C Halogen Lamp 42A ４２42B CCD sensor 43 Image information detection unit 54 Overall control unit 212 Heating roller 213 Pressure roller 221 Heater lamp 222 Temperature sensor S Recording medium TA to TC, T1, T2 Fixing test image

Claims (9)

[Claims] 1. An image forming device comprising: a test image data obtaining device for obtaining test image data for generating a predetermined test image; an image forming device for generating an unfixed image on a recording medium; A fixing unit for fixing the unfixed image on the recording medium, wherein one of the image forming unit and the fixing unit includes at least one of the process conditions of the image forming process. A light emitting element for irradiating light to a fixing test image fixed on the recording medium by the fixing means, comprising: an image forming process condition changing means capable of changing conditions in a direction orthogonal to the recording medium transport direction; and the light emitting element. A light receiving element for detecting intensity information of light reflected or transmitted from the fixing test image irradiated from the Image information detecting means for detecting image information of the fixing test image at least at two or more locations of the recording medium at different positions in a direction orthogonal to the recording medium transport direction at a fixed detection timing; and Initial image information storage means for storing initial image information detected by the information detection means; detection timing determination means for determining the predetermined detection timing of the image information detection means; and detection timing determined by the detection timing determination means An image information comparing means for comparing the image information detected by the image information detecting means with the initial image information stored in the initial image information storing means; and an image forming process based on the comparison result in the image information comparing means. An image forming process condition correcting means for correcting a process condition in the condition changing means, An image forming apparatus, comprising. 2. The image forming apparatus according to claim 1, wherein the image forming process condition changing unit includes a plurality of chargers for applying a charge to a photoconductor in a direction orthogonal to a recording medium conveying direction. An image forming apparatus, wherein the image forming process condition correcting means is a charging condition correcting means for correcting the charging condition of each of the charging devices. 3. The image forming apparatus according to claim 1, wherein the image forming process condition changing unit moves the developer carrier that supplies the developer to the electrostatic latent image on the photoconductor at right angles to the recording medium conveyance direction. And a developing bias voltage value to be applied to the plurality of developer carrying members, the developing bias voltage values being applied to the plurality of developer carrying members, respectively. An image forming apparatus, which is a developing condition correction unit that corrects a bias voltage value. 4. The image forming apparatus according to claim 1, wherein the image forming process condition changing unit moves a transfer unit that transfers a visible image on a photoconductor onto the recording medium in a direction orthogonal to a recording medium conveyance direction. A plurality of transfer devices, each of which is capable of changing any one of a transfer current and a transfer voltage in the plurality of transfer devices, wherein the image forming process condition correcting device includes any one of the transfer current and the transfer voltage in each of the transfer devices An image forming apparatus, wherein the image forming apparatus is a transfer condition correcting unit that corrects the difference. 5. The image forming apparatus according to claim 1, wherein the fixing unit includes a plurality of heaters in a direction orthogonal to a recording medium conveyance direction, and fixes the unfixed image on the recording medium by contact heating. The image forming process condition changing unit is a divided heating unit that can change the control temperature of each of the plurality of heaters, and the image forming process condition correcting unit is the contact heating and fixing unit. An image forming apparatus, comprising a fixing temperature correction unit for correcting a fixing temperature. 6. An image generating means for obtaining a test image data for generating a predetermined test image, an image generating means for generating an unfixed image on a recording medium, and an image generating means for generating an unfixed image on a recording medium. A fixing unit for fixing the unfixed image on the recording medium, wherein the light emitting element irradiates light to a fixing test image fixed on the recording medium by the fixing unit; and A light-receiving element for detecting intensity information of light that has been irradiated and reflected or transmitted through the fixing test image, and at least two or more locations in the initial state and at a predetermined detection timing, where the positions of the recording medium in the recording medium transport direction are different. Image information detecting means for detecting image information of the fixing test image, and the image information detecting means detecting the image information in the initial state. Initial image information storage means for storing initial image information; detection timing determination means for determining the predetermined detection timing of the image information detection means; and the image information detection means at the detection timing determined by the detection timing determination means Image information comparing means for comparing the detected image information with the initial image information stored in the initial image information storing means; and at least one of the image creating means and the fixing means based on a comparison result in the image information comparing means. An image forming apparatus comprising: an image forming process condition correcting unit configured to correct any one of process conditions in a recording medium conveyance direction. 7. The image forming apparatus according to claim 6, wherein the image forming unit includes a charging unit that applies a charge to a photoconductor, and the image forming process condition correcting unit includes a charging condition in the charging unit. An image forming apparatus comprising: a charging condition correction unit configured to correct the image. 8. The image forming apparatus according to claim 6, wherein said image forming means has a developer carrier for carrying a developer for supplying a developer to an electrostatic latent image on a photoconductor. The image forming apparatus is characterized in that the image forming process condition correcting means is a developing condition correcting means for correcting a developing bias voltage value applied to the developer carrier. 9. The image forming apparatus according to claim 6, wherein the image forming unit includes a transfer unit that transfers a visible image on a photoconductor onto the recording body, and the image forming process condition correcting unit includes: An image forming apparatus comprising: a transfer condition correcting unit for correcting any one of a transfer current and a transfer voltage in the transfer unit.