JPH0887212A - Image forming device - Google Patents

Abstract

PURPOSE: To reproduce color images of various kinds of forms such as a dot image, a line and a solid image with an accurate color tone by controlling a developing action with a developing device for developing the first and second colors by using plural developing devices, thereby obtaining an accurate color image. CONSTITUTION: An image signal for modulating a laser light source 35 is outputted from a host through a printer controller and the surface of a photoreceptor drum 29 primarily electrified by an electrifying pole 40 is exposed to execute the image exposure of the first color. Then, the yellow toner is developed as the first color by the developing device 30, and the surface of the drum 29 is electrified again by the electrifying pole 40 to execute the image exposure of the second color. Then, magenta toner is superimposed to execute the development by the developing device 31. Thereafter, the cyan toner and black toner of the third and forth colors are successively superimposed and the reelectrification, image exposure and development are executed similarly. A toner image formed as an accurate color image by the superimposing of the color toner and exposure control on the surface of the drum 29 is transferred to a recording paper P by a transfer belt 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus, in which a pattern electrostatic latent image is formed on an image bearing member by using a laser light source, for example, and the process of developing with a color toner is repeated a plurality of times. When a color image is formed by using color toners of a plurality of colors in particular, an edge dot in the image is detected, and the exposure condition is changed according to user adjustment or environmental conditions to make it faithful. The present invention relates to an image forming apparatus adapted to obtain a color image or a monocolor image.

[0002]

2. Description of the Related Art A conventional color image system for obtaining a desired color image by superposing color toners by an electrophotographic system will be described. First, FIG. 1 (a) confer first charge at such charging electrode E1 made in the surface potential V _S to the image carrier E2 for forming a color toner image. Then the image or text,
As shown in FIG. 1 (b), image exposure is performed with a laser beam or the like only on a portion where a line image or the like should be formed. After the image exposure is completed, the charge is erased only in the exposed portion, the surface potential V _S is lowered to V _L , and the charge in other non-image portions is not erased. Next, as shown in FIG. 1C, the image carrier E2 is moved in the direction of the arrow by the developing device D to perform the first development, that is, the first color development. By the image exposure of FIG. 1 (b), electric charges are erased in a well type potential,
The toner of the first color adheres to the erased portion and is developed to form a toner image of the first color. Next, as shown in FIG. 1D, second charging is performed (recharging) by the strip electrode E1 including the toner image portion of the first color. The surface potential is controlled so as to be approximately the same potential V _{S as} that at the first charging. The toner image on the relationship between the first color description separated from the image bearing member E2, illustrated in the position of the surface potential V _S unit. Next, as shown in FIG. 1E, a second image exposure is performed on the toner image of the first color, so that electric charges are erased in a well-shaped potential only in the image exposed portion as in FIG. 1F. Second image exposure of one pass through the color toner image reaches on an image bearing member, the surface potential of this portion is exposed portion potential V _L plus potential V ₁ of the toner image to the potential (V _L + V ₁ ). Then, on the image carrier E2 shown in FIG. 1B, the developing device D develops the toner of the next second color by superposing it on the toner of the first color. When developing the third color, recharging, image exposure and development may be repeated. The above is the basic process of forming a color image on the image bearing member by superimposing color toners.

To create a color toner image by superposing the above-mentioned toners, image information is inputted from the outside through an interface circuit and is subjected to necessary processing to record it, that is, a so-called photoconductor is used as an image carrier. Performed by the electrophotographic printer. Of course, it may be a color copier that reads a color original document, converts it into an electric signal, and then records and copies it in the recording section. For example, in FIG. 2A, a host 100 having a built-in computer (hereinafter referred to as CPU) and equipped with a display and the like, and a printer controller 101.
And a laser printer unit 102. Image information such as characters, dots, lines, and solid images stored in a storage unit such as a RAM and recorded in a recording unit in the CPU is output to the printer controller 101. After the video signal from the printer controller 101 is processed for color recording, a recording signal is created, whereby the semiconductor laser is modulated and recorded by the laser printer 102. For example, the red character A is sequentially output as a dot image, and the laser printer 102 outputs only the character portion as a dot signal.
Input to the laser printer 102 shown in FIG.
The toner images are formed in the order of (a), (b), (c), (d), (e), and (f).

As a modulation method of a semiconductor laser, a recording signal is converted into a pulse width within one pixel or a plurality of pixels,
There are a pulse width modulation method that uses a laser modulation signal and an intensity modulation method that increases and decreases the laser emission intensity, both of which are used as image exposure modulation methods of a color toner superposition method. This is convenient when changing the size of the recording dots of the first and second colors.

For example, when creating a red color by using yellow and magenta, it is necessary to perform color adjustment when weakening yellow and weakening magenta, conversely to weakening yellow and magenta. The desired color image is obtained by changing the exposure conditions and adjusting the mixing ratio by superimposing the color toners. Color adjustment generally means adjusting the balance of the amount of toner adhered to the image forming body of the first color toner and the second color toner and thereafter. In the above color image formation, when the second color is exposed, especially when the first color toner is charged and exposed.
There is a drawback that the development of color toner is difficult because the influence of the toner layer of the color is extremely large.

That is, it is assumed that the user desires to obtain a red color tone obtained by superimposing a yellow toner and a magenta toner by an image forming apparatus, for example, in a color tone in which one of yellow and magenta is emphasized. At this time, in the image forming apparatus having a function for the user to adjust the color tone,
Color adjustment is performed by adjusting the amount of the yellow and magenta toners attached to the image forming body. In addition, the color adjustment according to the user's desire is called user adjustment.

Further, when the temperature and humidity of the environmental conditions around the image forming apparatus fluctuate, the chargeability of the developer, the surface potential V _S , the exposed portion potential V _L, etc. of the photosensitive member fluctuate, and as a result, During development, the amount of toner adhered to the surface of the photoconductor fluctuates. Therefore, when the temperature and humidity conditions change, the image forming apparatus changes the exposure condition to adjust the potential difference between the surface potential V _S and the exposed portion potential V _L to keep the toner adhesion amount constant, and Color adjustment is performed by adjusting the balance of the amount of toner adhered to the image forming body of the first color toner and the second color toner and thereafter.

Further, the photoreceptor and the developer are deteriorated by repeating the image forming process. That the life of the photosensitive member and / or developer, charging property in a developer, the surface potential V _S is at an image forming body, the exposed portion potential V _L and the like is fluctuated, resulting in an image forming surface during development The amount of toner adhered to the toner fluctuates. Therefore, in the image forming apparatus, the exposure condition is changed according to the life of the photoconductor and / or the developer to adjust the potential difference between the surface potential V _S and the exposed portion potential V _L to keep the toner adhesion amount constant. The color adjustment is performed by adjusting the balance between the toner adhesion amount of the first color toner and the second and subsequent color toners to the image forming body.

However, the above-mentioned color adjustment has the following problems. That is, as shown in FIG.
The image signals output from the CPU to the printer controller 101 include characters which are dot signals, dotted lines, solid images and the like, and it is desirable that the color tone is the same in any image pattern. However, the color adjustment cannot always change the color tone in the same manner for each image pattern. For example, in the case of changing the duty ratio of the lighting time of the exposure apparatus, a so-called pulse width modulation method will be described first with reference to FIG. In FIG. 3B, assuming that signals are sequentially input from the left side, dot signals are first input and solid image signals are input at intervals, and the input signals are video signals from the printer controller 101, which are control units of the laser printer 102. Is output to.

The video signal is converted into a pulse signal by a pulse width modulation circuit (not shown) in the control section of the laser printer 102, an ON signal is issued by the output of dots, and a pulse having a constant width is formed. Next, a solid image video signal is input to the laser printer 102 at intervals, and when a pulse signal having a constant width and a constant interval is turned on, the signal is emitted. For example, if the duty ratio is 50% and the second color is 100% in order to limit the adhesion amount of the first color,
In the distribution of the light energy density received by the photoconductor as shown in FIG. 3A, there is a large difference in energy density between the edge duty ratio of 50% and the solid image duty ratio of 50%. That is, since the solid image is the sum of the energies of the dots that are close to each other, the average energy is larger than the energy of a single isolated dot, one dot line, or the edge portion of the solid image portion (hereinafter referred to as the edge portion or edge portion). Become. Therefore, the difference in light energy between the case where the duty ratio of the solid portion is 50% and the case where the duty ratio is 100% is small as shown in FIG. 3A, and this state is changed by the image carrier of FIG. 1B. The exposed surface potential curve is shown in Fig. 3 (b).
When the ratio is 50% and the duty ratio is 100%, the surface potential is large like VS ₁ . That is, the duty ratio is 50% and the duty ratio is 100%
In the case of, the surface potential increases by ΔVS ₁ .

In this state, the solid image portion has a very low surface potential of ΔVS ₂ as shown in the figure even if the charge is erased by image exposure at a duty ratio of 50% and a duty ratio of 100%. That is, FIG. 1 (c), (d), (e),
When the image forming process shown in the order of (f) is performed, the state of charge erasing by image exposure at a duty ratio of 50% is shown in FIG. In the edge portion and the solid image portion, the potential drop in the edge portion is small, so that FIG.
As shown in (1), when the development is performed by the developing device D, the toner adhesion amount is extremely small, and the potential drop is large in the solid image portion, so that the toner is sufficiently adhered.

Next, as shown in FIG. 4 (b), re-charging is performed on the toner image of the first color development, and as shown in FIG. 4 (c), the image of the second duty ratio 100% for the second color development. Perform exposure. In this case, since a small amount of toner adheres to the edge portion on the image carrier E2 during the development of the first color, a large amount of light energy is projected during the image exposure of the second color, so that the potential drops greatly.
Since the amount of toner adhered to the solid image portion is large, the projection of light energy during image exposure of the second color is small, so that the potential drop is smaller than that at the edge portion as shown in the figure. When the duty ratio of the first color is reduced as described above, a large difference occurs in the potential drop of the second color between the edge and the solid image portion. Here, when the second color toner development is performed by the developing device D, a large amount of toner adheres to the edge portion because the charges are largely erased in the edge portion. That is, when the duty ratio during image exposure of the second color is larger than that of the first color (50% → 100%), the toner adhesion amount of the second color becomes extremely large in the edge portion compared to the toner amount of the first color, There arises a problem that the color tones of the dots and the solid image portion change and color adjustment is required.

There is another method of color adjustment, for example, a method of changing the developing condition for each color to control the amount of developing toner, but this method also varies the amount of adhesion depending on the image pattern and consequently changes the color tone. For example, in a developing system in which an alternating voltage is applied to the developing bias, the amount of developing toner can be controlled by changing the strength of the alternating voltage. However, it has been found that when the AC voltage is increased, the amount of the developing toner increases more in the dots and lines than in the solid image. Therefore, there is a disadvantage that the solid and dots and lines change the color tone. In addition to the above-mentioned drawbacks, if the image density is adjusted for a monochrome image, the characters may be crushed, blurred, or fine lines may be cut even if the solid image portion has a desired density. is there. When reproducing a color image, even if the solid portion is reproduced in a desired color even when color adjustment is performed, the color of the end portion, point, or line of the solid image portion may not be reproduced in the desired color.

Furthermore, when color adjustment is performed during reproduction of a color image, the resolution is changed, characters and the like become unclear, and the image quality is deteriorated.

[0015]

The present invention is a device specifically conceived to remedy the aforementioned drawbacks. That is, when adjusting the density of a monochrome image, all solid image portions, edges such as dots, characters, and fine lines are reproduced clearly. Further, also when reproducing a color image, when reproducing a desired color by performing color adjustment, all of the solid image portion and the edge portions such as dots, characters and lines are reproduced in the same color.

[0016]

That is, an image forming apparatus according to a first aspect of the present invention forms an latent image on a photosensitive member by using an exposing unit that forms an image forming signal, and forms a toner image by developing unit that uses toner. In the device, the developer life detecting means,
At least one detection unit selected from a photoconductor life detection unit and a temperature / humidity detection unit, a determination unit that determines an image forming signal of an edge dot from the image forming signal, and a writing adjustment condition by the exposure unit. The image forming signal of the edge dot discriminated by the discriminating means is changed to the first condition according to the information of the detecting means, and the image forming signal of the dot other than the dot discriminated by the discriminating means is changed. Is different from the first condition, and has a control means for adjusting the amount of toner adhered to the photosensitive member by changing to the second condition according to the detection information.

The image forming apparatus according to a second aspect of the present invention forms a latent image on a photoconductor by using an exposing unit according to an image forming signal,
In an image forming apparatus that forms a toner image with a developing unit using toner, a user adjusting unit that determines color adjusting conditions, a determining unit that determines an image forming signal of an edge dot from the image forming signal, and a writing by the exposing unit. The adjustment condition is changed to the first condition according to the color adjustment condition for the image forming signal of the edge dot discriminated by the discriminating means, and the image of the dot other than the dot discriminated by the discriminating means is changed. The forming signal is different from the first condition, and is changed to a second condition corresponding to the color adjusting condition to have a control unit for adjusting the amount of toner adhered to the photoconductor.

[0018]

According to the image forming apparatus of the present invention, since the image forming apparatus has the detecting means and the determining means, the writing adjustment by the exposing means is performed for each of the dots other than the dot which is determined to be the edge portion and the dot which is determined to be the edge portion. Adjust the conditions.

Further, since the image forming apparatus according to the second aspect of the present invention has the user adjusting means and the determining means, the exposure means determines the dots of the portions other than the dots which are determined to be the edge portions by the exposure means according to the detection information of the detecting means. Adjust the write adjustment conditions.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the configuration of a printer device according to an image forming apparatus of the present invention will be described with reference to FIG.

In FIG. 6, reference numeral 1 denotes a lower frame of the image forming apparatus. In the lower frame 1, a half-moon-shaped paper feed roller 2 for feeding a recording paper P which is a transfer body is provided. A paper feed cassette 3 containing a plurality of sheets is detachably provided in the lower frame 1. A push-up plate 4 which is pushed up by a spring 5 is provided in the paper feed cassette 3, the recording paper P is placed on the paper feed cassette 3, and a separation claw 6 rotatably provided on a part of the paper feed cassette 3 is used for recording. The paper P is locked at the uppermost end of the tip. A guide plate 7 guides both sides of the recording paper P and is provided so as to be adjustable depending on the size of the recording paper. The above configuration is provided in the paper feed cassette 3. Reference numeral 8 denotes a conveyance roller for the recording paper P provided on the lower frame 1, and is provided between a guide plate 9 for guiding the leading end of the recording paper P fed by the paper feed roller 2 and a reversing guide plate 10. .

Reference numeral 11 denotes a guide plate for guiding the recording paper P to the registration roller 12 after the recording paper P is reversed and fed, and guides the recording paper P to the registration roller 12. 13 is the registration roller 12
The sensor S ₁ for detecting the recording paper P at the position
It is a swinging member that turns on and off. 14 is a registration roller 12
Is a guide plate that guides the recording paper P that has passed through to the transfer belt 15 in the direction of the transfer belt.
It is suspended on 17 and a drive roller 18. Reference numeral 15a is a cleaning means for cleaning the surface of the transfer belt 15. Reference numeral 19 denotes a fixing device for fixing the image transferred on the recording paper P. The fixing device 19 is composed of a fixing heating roller 20 and a pressure roller 21, and a cleaning roller 20a is pressed against the fixing heating roller 20 and cleaned according to the rotation. To do. 22 is a fixing device 19
A swinging member 2 for turning on and off the sensor S ₂ for confirming the discharge of the recording paper P by the discharging roller for discharging the recording paper P
3 is activated by recording paper when ejecting. The discharged recording paper P is recorded by the recording paper guide member 24, the guide passage 25 formed in the upper frame 1c, and the guide conveying rollers 26, 27.
The recording paper P is ejected to a paper ejection tray 28 provided on substantially the entire upper surface of c. Next, an image carrier 29 for image formation (hereinafter referred to as a photoconductor drum) is formed in a substantially central portion of the upper frame 1c.
29), and four sets of developing devices 30, 31, 32, 33 can be arranged from the top along the surface of the photosensitive drum 29. Reference numeral 34 is a polygonal mirror, which emits a laser beam emitted from a laser light source (not shown).
The light passes through the θ lens 35 and is reflected by the reflection mirrors 36, 37 and 38 to expose the photosensitive drum 29. 39 is the polygon mirror
An optical system frame body integrally incorporating optical systems such as 34 and reflection mirrors 36, 37 and 38, and is incorporated in the uppermost part of the upper frame body 1c.

Reference numeral 40 denotes a strip electrode for charging the entire surface of the photosensitive drum 29, which is provided on a part of the upper frame 1c. 41
Is a cleaning blade for cleaning the residual developer adhering to the surface of the photosensitive drum 29 after the image is transferred from the photosensitive drum 29 to the recording paper P, and is a conveyance for discharging the cleaned developer to the outside. An apparatus 43 is provided to convey the developer scraped off by the cleaning blade.
A developer receiving member 42 that efficiently sends the toner to the cleaning blade 43 is provided below the cleaning blade 41. The developer conveyed to the outside by the conveying device 43 is conveyed to the container 44 by the conveyer 45 so that an appropriate amount can be accumulated in the container 44, and the developer can be removed and discarded. Reference numeral 46 denotes a developer container for supplying a developer to each of the developing devices 30, 31, 32, and 33. Although the developer container shown in the drawing is only one set, four sets are provided side by side. For example, cyan, magenta, yellow, and black color developers are supplied to 30, 31, 32, and 33 to perform color development. Reference numeral 47 is a manual tray which can manually feed the recording paper P. The lower frame 1 and the upper frame 1c are assembled so that the conveyance path of the recording paper P can be opened around the support shaft 1b, and the recording paper P is in a defective conveyance state during feeding and conveyance. When at least the fixing device 19 is not reached, the upper frame 1c can be opened around the support shaft 1b and the recording paper P can be taken out. Further, there is provided a guide plate 1a that allows the recording paper P provided on the lower frame 1 to be supplied from another paper feeding device (not shown).

The photosensitive drum 29 is provided on a frame 41a provided with a cleaning blade 41 via a support shaft 29a, and the support shaft 29a is pivotally supported on the upper frame 1c.

In the above-described image forming apparatus, the host 100 outputs an image signal for modulating the laser light source 35 via the printer controller 101, so that the surface of the photosensitive drum 29 which is primary charged by the band electrode 40 is removed. Imagewise exposure. This image exposure is the image exposure of the first color shown in FIG. 1 (b) as described above.

Next, as the first color, the developing device 30 develops yellow color toner, and as shown in FIG.
After recharging at 40 and image exposure of the second color by the laser light source as shown in FIG. 1 (e), magenta color toner is superposed and developed by the developing device 31.

Thereafter, similarly, a cyan color toner as the third color and a black toner as the fourth color are successively overlapped and recharged image exposure and development are performed to form a color toner image of four colors on the surface of the photosensitive drum 29. .

As described above, charging, image exposure and development are sequentially performed on the surface of the rotating photosensitive drum 29, color toners are superposed, and a toner image formed into an accurate color image by exposure control is formed on the recording paper P. Transfer device 15 for transfer and fixing device 19
The toner image is fixed on the recording paper at.

The gap between the photosensitive member and the developer carrying member is 0.2 mm to 0.8 mm, and the developer is a two-component developer comprising a mixture of carriers which are magnetic particles and toner which is non-magnetic particles. There is.

The weight average particle size of the carrier is, in this example,
The weight average particle diameter of the toner is 5 to 20 microns, preferably 15 to 80 microns and preferably 20 to 50 microns. The developer is regulated on the developer carrier to a desired layer thickness by the layer thickness regulating means. The layer thickness is preferably slightly thinner than the gap between the photoconductor and the developer carrying member. The developer carrying member is made of a conductor or a conductor having an insulating layer on the surface, and a DC or alternating (AC) electric field is applied between the developer carrying member and the photoconductor as a developing bias.

Further, the surface potential V _S of the white background portion of the photoconductor is set to −7.
The exposure portion potential _VL is -30 to -700V. As the developing bias of each color, the peak is at DC voltage of -600V.
Two-peak 2.0 to 2.8kV AC voltage is applied.

Using the above color image forming apparatus, the developer is composed of a carrier in which a ferrite core is resin-coated with an insulating carrier having a weight average particle size of 45 μm, and a system color toner having a weight average particle size of 8 μm. Development was performed by a non-contact development method using a component developer.

Next, the write adjustment conditions of the image forming apparatus of the present invention will be described.

As shown in FIGS. 2 (a) and 2 (b), characters, lines, dotted lines, etc. are output as dot signals in the video signal from the printer controller 101, and a solid portion is output as a solid image signal. The first color is output as a signal. The control means in the laser printer 102 receives the video signal generated by the printer controller 101. Inside the laser printer 102, as shown in FIG. 2B, an edge detection circuit section 104 and a color recording correction circuit section 105,
A recording image signal processing unit 103 having an image density adjusting unit, a color tone adjusting unit, and a gamma correcting unit 106 is incorporated. The environment detection unit 109 has a counter 109a, a temperature sensor 109b, and a humidity sensor 109c, and detects data for monitoring the life of developer and photoconductor, temperature, and humidity. Further, a mechanical controller control unit 107 and a laser drive unit 108 are provided in the control means in the laser printer 102. The counter 109a counts the number of times an image is formed by the laser printer 102, and counts the number of consumed papers to 1
A signal corresponding to the count is output to the mechanical controller control unit 107 for each count. The mechanical controller control unit 107 obtains the integrated value of the number of consumed paper sheets as the detection information from the signal corresponding to the 1 count. From the integrated value, the mechanical controller control unit 107 obtains an integrated value of the number of papers after replacement of the developing device to calculate the life of the developer, and obtains an integrated value of the number of papers after replacement of the photoconductor to determine the life of the photoconductor. calculate. Temperature sensor 109
b, the humidity sensor 109c sends a signal corresponding to the temperature and humidity inside the laser printer 102 to the mechanical controller control unit 10
Output to 7. The user adjustment value input unit 110 is an operation unit for the user to control the color tone as desired, and is related to the user adjustment means of the present invention. The mechanical controller control unit 107 communicates with the recording image signal processing unit 103 according to the life of the photosensitive member and the developer which are the detection information, the temperature and humidity in the laser printer 102, and the user adjustment value that determines the color adjustment condition. Input / output control with.

With the above configuration, when the character A, for example, shown in FIG. 2A is output as a dot image by the video signal, the edge detection circuit section 104 detects the edge section. In this embodiment, the edge portion is detected using a matrix of 3 × 3 pixels, and it is discriminated for each pixel whether the pixel of interest is an edge portion or a non-edge portion by observing the change in density between adjacent pixels in the main scanning direction and the sub scanning direction. . Further, the color recording correction circuit unit 105 corrects the color recording image and the gamma correction unit 106 corrects the gamma, and the mechanical controller control unit 10
Input / output control of detection information and / or color adjustment conditions between the control unit and the mechanical controller
Input / output control is also performed between 107 and the laser drive unit 108. The edge portion or the non-edge portion is discriminated for each pixel, and an image forming signal is sent to the laser driving unit 108 under the write adjustment condition according to the detection information and / or the color adjustment condition. By controlling the dot or solid image signal at the edge portion, the laser printer 102 is exposed as an electric signal under the writing adjustment conditions shown in Tables 1 to 9 below. By adjusting the write adjustment conditions as shown in Table 1 to Table 9, for example, FIG.
When the pulse width modulation exposure shown in (b) is performed, both the dot image portion and the solid image portion of the edge portion of the first color are shown in FIG.
As shown in (a), the exposed portion potentials V _L become equal. Then, when the image is developed by the developing device 30, the toner adhesion amount becomes substantially the same as shown in FIG. 5C. Next, as shown in FIG. 5D, recharging is performed, then the write adjustment conditions are adjusted as shown in FIG. 5E, the edge portion is exposed under the first write condition, and the solid portion is exposed under the second write condition. Expose. In the image forming apparatus of the present invention, since the toner adhesion amounts at the time of developing the toner image at the edge portion and the solid portion are almost the same, the exposure portion potential _VL of the second color is made substantially the same so that the development of the second color is finally performed. Device 3
Even if development is performed using 1, the toner adhesion amounts of both are almost the same and the toner adhesion amount of the first color is also the same.

Examples of the write adjustment conditions of the image forming apparatus according to the present invention described above will be described with reference to Tables 1 to 9. However, in Table 1 to Table 9, the solid part and the edge part are indicated as solid and edge, respectively. The life of the photoconductor is represented by the number of sheets of paper on which an image is formed using the photoconductor. The life of the developer is represented by the number of sheets of paper on which an image is formed using the developing device of the image forming apparatus. K when displaying the number of papers is
It is 10 ³ (km). Further, in the embodiment in which the writing adjustment condition is adjusted by the exposure intensity modulation method, the exposure intensity of the solid portion when the developer life is 0 to 300 (sheets) at a humidity of 50% is 100%.
I am trying.

The embodiment shown in Table 1 is an embodiment of the image forming apparatus having a photoconductor life detecting means as the detecting means and changing the writing adjustment condition by the exposure intensity modulation method.

[0038]

[Table 1]

In Table 1, the exposure intensity (LDP) according to the exposure intensity modulation system is shown for each life of the photoconductor. The photoconductor life is shown every 10 k (sheets). The exposure intensity of the solid part and the edge part is 0% to 10k (sheets), and the exposure intensity of the solid part is 110% at 10k (sheets) to 20k (sheets). Strength is 1
20%. Photoconductor life is 20k (sheets) to 30k
In the case of (sheets) or 30k (sheets) to 40k (sheets), the write adjustment condition is adjusted as shown in Table 1. Table 1
The writing adjustment condition for the exposure intensity of the edge portion relates to the first condition of the present invention, and the writing adjustment condition for the exposure intensity of the solid portion relates to the first condition of the present invention. Further, the effect was obtained by adjusting the write adjustment condition in this way.

The embodiment shown in Table 2 has a photoconductor life detecting means as a detecting means, and the writing adjustment condition is changed by using the pulse width modulation method in addition to the exposure intensity modulation method. 3 is an example of the image forming apparatus. The image forming apparatus according to this embodiment performs exposure intensity modulation as shown in Table 1 above, and further adjusts the duty ratio when exposing the first and second colors as shown in Table 2.

[0041]

[Table 2]

That is, when the photoconductor life is 0 to 10 k (sheets), the exposure intensity (L.D.P.) of the first and second colors is 100.
In addition, the duty ratio of the solid part is 35% for the first color,
The second color is 100%. The duty ratio of the edge part is 40% for the first color and 100% for the second color. Further, when the photoconductor life is 10 k (sheets) to 20 k (sheets), the exposure intensity is 110% in the solid portion, and the duty ratio is 35% for the first color and 90% for the second color. And the exposure intensity of the edge is 120%
The duty ratio is 40% for the first color and 90% for the second color. The photoconductor life is 20k (sheets) to 30k (sheets) or 30
In the case of k (sheets) to 40 k (sheets), the writing adjustment condition is adjusted to the exposure intensity shown in Table 1 and the duty ratio shown in Table 2.

Table 3 shows an embodiment of the image forming apparatus which has a developer life detecting means and a humidity detecting means as detecting means, and adjusts the writing adjustment condition by the exposure intensity modulation method.

[0044]

[Table 3]

In the embodiment of Table 3, the adjustment values of the exposure intensity of each of the solid portion and the edge portion are displayed in the column as the exposure intensity of the solid portion / the exposure intensity of the edge portion.

When the developer life is 0 to 300 (sheets) and the humidity is less than 15%, the exposure intensity of the solid portion is adjusted to 150% and the exposure intensity of the edge portion is adjusted to 170%. Also developer life 0-300
When the humidity is 15% or more and less than 19% in (sheet), the exposure intensity of the solid part is adjusted to 150%, the exposure intensity of the edge part is adjusted to 160%, and the developer life is 300 to 8K (sheet) and the humidity is less than 15%. The exposure intensity of the solid part is 200%, and the exposure intensity of the edge part is 220%
Is adjusted to. The adjustment is similarly performed under other conditions. The adjustment value of the exposure intensity of the edge portion shown in Table 3 is related to the first condition of the present invention, and the adjustment value of the exposure intensity of the solid portion is the second value of the present invention. It depends on the conditions.

The embodiment of Table 4 shows an embodiment of the image forming apparatus which has a developer life detecting means and a humidity detecting means as the detecting means, and adjusts the writing adjustment condition by the pulse width modulation method.

[0048]

[Table 4]

That is, when developing red, red is obtained by mixing yellow toner (Y) and magenta toner (M). In the image forming apparatus of this embodiment, the humidity is 21%.
If less than the above, the solid portion has a duty ratio of 35% and a latent image to be developed is written with the first color yellow toner, and the latent image is developed with the yellow toner to form a toner image. Subsequently, a latent image to be developed with magenta toner is written at a duty ratio of 100%, the latent image is developed with magenta toner, and a toner image in which yellow toner and magenta toner are superposed is formed. On the other hand, the edge portion writes a latent image to be developed with yellow toner at a duty ratio of 65%, and a latent image to be developed with magenta toner at a duty ratio of 100%.
The write adjustment conditions are adjusted so as to write with.

Separately, when forming an image in which a red image and a green image are mixed at a humidity of 21 to 34%,
For the latent image to be developed with the first color yellow toner, the image signal corresponding to red is written in the solid portion with a duty ratio of 30%, the edge portion is written with a duty ratio of 55%, and the image signal corresponding to green is written in the solid portion with a duty ratio. The write adjustment condition is adjusted so that the edge portion is written at 40% and the duty ratio is 55%. Further, a latent image to be developed with a magenta toner which is a second color toner forming a red color and a cyan toner which is a second color toner forming a green color is a solid portion and an edge portion of both latent images.
Adjust the write adjustment conditions so that the uty ratio is 100%.

As described above, in the image forming apparatus of this embodiment,
When developing a red color at a humidity of 21% or less, the latent image of the edge portion to be developed with yellow toner has a duty ratio of 65%, and the latent image of the edge portion to be developed with magenta toner has a duty ratio of 100%. Under the first condition of the present invention, the latent image of the solid portion to be developed with yellow toner has a duty ratio of 35%, and the latent image of the solid portion to be developed with magenta toner has a duty ratio of 1%.
The second condition of the present invention is set to 00%.

The examples shown in Tables 5 to 7 have a developer life detecting means and a humidity detecting means as the detecting means, and the write adjustment condition is that the pulse width modulation method is used together with the exposure intensity modulation method. 7 is an example of an image forming apparatus configured to adjust a writing adjustment condition.

[0053]

[Table 5]

[0054]

[Table 6]

[0055]

[Table 7]

In the image forming apparatus according to this embodiment, the exposure intensity is adjusted according to the developer life and the humidity as shown in Table 5, and then the writing adjustment is performed so as to perform the pulse width modulation shown in Tables 6 and 7. Adjust the conditions. Table 6 shows which of the pulse width modulation Duty ratios in the first to fifth columns of Table 7 is selected according to the developer life and the humidity.

That is, when the humidity detecting means detects a humidity of 40% and the developer life detecting means detects 5 k (sheets), the exposure intensity is adjusted to 120% as shown in Table 5. The duty ratio by pulse width modulation is adjusted to the write adjustment condition shown in the third column of Table 7 as shown in Table 6. Then, as shown in the third column of Table 7, the write adjustment conditions for the edge portion and the solid portion of the red, green, and blue images are adjusted.

The embodiment shown in Table 8 is an embodiment of the image forming apparatus having the user adjusting means and adjusting the write adjusting condition by the pulse width modulation method according to the user adjusting value.

[0059]

[Table 8]

That is, when a user desires to obtain a secondary color by superimposing a plurality of colors, the duty ratio is sequentially adjusted to -5% and -10% when the user desires to obtain a tone with a weakened first color. Conversely, when the user wants to obtain the first color with a stronger color tone, the duty ratio is adjusted to + 5% and + 10% in sequence.

Furthermore, when the user adjustment is performed by adjusting the write adjustment condition by the pulse width modulation method, Table 4
It is necessary to correct the set value of the Duty ratio shown in. On the other hand, the set value of the duty ratio shown in Table 4 corresponds to the case where the tone adjustment of the first color is set to ± 0% in the examples of Table 8. Further, although the set value of the duty ratio when the duty ratio is sequentially adjusted in this embodiment is not shown, for example, a look-up table (LUT) is prepared and the duty ratio is set corresponding to each user adjusted value. Correct the ratio setting value.

In the embodiment of Table 9, the writing adjustment condition is adjusted by the pulse width modulation method according to the user adjustment value in the embodiment of Table 8, whereas the writing adjustment condition is adjusted by the exposure intensity modulation method. To do.

[0063]

[Table 9]

That is, when the user desires to obtain a secondary color by superimposing a plurality of colors, the exposure intensity is sequentially adjusted to -5% and -10% when the user desires to obtain a tone with a weakened first color. On the contrary, when the user wants to obtain the first color with an enhanced color tone, the exposure intensity is adjusted sequentially to + 5% and + 10%.

Similarly to the embodiment of Table 8, the exposure intensity set value when the exposure intensity is sequentially adjusted in this embodiment is not shown, but for example, a lookup table (LUT) is set.
It is needless to say that (1) is prepared to correspond to each user adjustment value.

By using the above values, there is almost no difference in color tone between the edge image portion such as a point, a line and the edge of a solid image and the solid image portion in any tone.

In the embodiments of Tables 8 and 9, the user adjustment is performed by a knob on the operation panel or a signal from the host 100. In the above example, the user adjustment value is continuously changed, but it may be adjusted stepwise by a step method.

Further, by using the adjusting method as described above, a color image can be formed in a desired color.

The exposure amount is controlled by changing the intensity modulation method control and pulse width modulation control of the semiconductor laser or by changing the dot configuration as described above, the color of the color image is adjusted, and the color image is recorded on the recording paper P by the laser printer. Could be formed.

In the above embodiments, the color image forming method by developing the color toners of two colors has been described. However, it is needless to say that the image forming control of three colors or more, or only one color can be applied to all the embodiments. Is. In this case, by changing the duty ratio of the edge image portion to the duty ratio of the solid image portion, the image is not crushed or cut, and the image density of the solid image portion can be adjusted.

As the exposure means of the present invention, only the exposure means by the laser beam has been described, but it goes without saying that an exposure means such as an LED array or a liquid crystal may be used. Whatever the exposure means, the amount of adhered toner can be controlled by changing the pulse width modulation method, the intensity modulation method, or the dot configuration.

Also. From the count value of the counter 109a of the present invention, the integrated value of the image forming times of each of the plurality of developing devices is obtained, and the writing adjustment condition is set to the integrated value of the image forming times of the developing device having the most advanced number among the plurality of developing devices. The writing adjustment condition may be adjusted according to the above, or the writing adjustment condition may be adjusted according to the integrated value of the number of image forming times of the developing device having the most delay among the plurality of developing devices. The writing adjustment condition may be adjusted according to the average value of the number of developing devices, or the writing adjustment condition may be adjusted according to the integrated value of the number of image formation times of the developing device which develops first on the photoconductor among a plurality of developing devices. May be adjusted, or the writing adjustment condition may be adjusted according to the integrated value of the number of times of image formation of the developing device which develops lastly on the photosensitive member among the plurality of developing devices. When the accumulated value of the number of image formations for each of multiple developing devices is obtained and the write adjustment conditions are adjusted for each developing device to adjust the amount of toner adhesion, the solid image portion of the color image is changed due to the life difference of each developing device. It is preferable that all dots, letters, and lines can be reproduced in the same color.

Further, in an image forming apparatus having a developing device for developing with black toner, a good image can be obtained without normally performing color adjustment for black. Therefore, only the black latent image is adjusted for writing adjustment conditions. It is also possible to perform the exposure without performing the adjustment and to adjust the write adjustment conditions for only the color toner.
In addition, the black image signal is likely to be a character image signal even in a color image. Therefore, without adjusting the writing adjustment conditions, diagonal line smoothing processing is performed separately to improve character quality. You may let me.

In the present invention, color images of all forms such as dots, lines, and solid images can be reproduced as accurate color tones, meaning that the edge portion and solid portion of the color image obtained by the image forming apparatus are

[0075]

[Outer 1]

In the color space of, the color difference ΔE is within 20 from the desired value (center value).

[0077]

According to the present invention, when reproducing a monochrome image, edge portions such as line drawings, isolated points (dots) and edges of solid portions are reproduced beautifully like solid portions. In particular, the reproduced image of a black line drawing, halftone dot image, and solid image mixed image has high image quality. As described above, when the color toner is developed by exposing the image output from the CPU or the image memory using a light source such as a laser beam, an LED array, a liquid crystal, etc., the first color development and the second color development are performed using a plurality of developing devices. The effect of performing the developing is that the developing operation by the developing device can be controlled to form an accurate color image, and a color image of any form such as a dot image, a line, or a solid image can be reproduced as an accurate color tone.

[Brief description of drawings]

1A to 1F show conventional charging, exposure, control,
FIG. 3 is a process diagram of an image forming unit showing a double development method of development.

FIGS. 2A and 2B are layout explanatory diagrams of the image forming apparatus from the CPU input to the laser printer.

3A to 3C are explanatory views of exposure control in an edge portion of an image and a solid image.

4A to 4D are explanatory views showing the development of color toner in a conventional edge portion and a solid image.

5A to 5F are explanatory views showing development of color toner in an edge portion and a solid image by the image forming apparatus in which the writing adjustment condition is adjusted according to the present invention.

FIG. 6 is a vertical cross-sectional view of an image forming apparatus using the image forming means of the present invention.

[Explanation of symbols]

 1 Lower frame 1c Upper frame 2 Paper feeding roller 3 Paper feeding cassette 7, 9, 10, 10, 11, 14 Guide plate 12 Registration roller 15 Transfer belt 20 Fixing heating roller 20a Cleaning roller 28 Paper ejection tray 29 Photosensitive drum ( Image carrier) 30, 31, 32, 33 Developing device 30a Developing device frame 34 Polygon mirror 35 fθ lens 36, 37, 38 Reflecting mirror 40 Strip electrode 109 Environment detection unit 109a Counter 109b Temperature sensor 109c Humidity sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Takeda 2970 Ishikawacho, Hachioji City, Tokyo Konica Stock Company

Claims (5)

[Claims] 1. An image forming apparatus in which a latent image is formed on a photoconductor by using an exposure unit based on an image forming signal, and a toner image is formed by a developing unit using toner, a developer life detecting unit and a photoconductor life detecting unit. , Temperature / humidity detecting means, at least one detecting means, a determining means for determining an image forming signal of an edge dot from the image forming signal, and a write adjusting condition by the exposing means by the determining means. The image forming signal of the determined edge dot is changed to the first condition according to the information of the detecting unit, and the image forming signal of the dot other than the dot determined by the determining unit is the first condition. An image forming apparatus, which is different from the condition and has a control unit that adjusts the amount of toner adhered to the photoconductor by changing to a second condition according to the detection information. 2. An image forming apparatus for forming a latent image on a photosensitive member by using an exposing unit for an image forming signal and forming a toner image by a developing unit using toner, and a user adjusting unit for determining a color adjusting condition. The discriminating means for discriminating the image forming signal of the edge dot from the image forming signal and the write adjusting condition by the exposing means, the image forming signal of the edge dot discriminating by the discriminating means are in accordance with the color adjusting condition. The first condition is changed, and the image forming signal of the dots other than the dots discriminated by the discriminating means is different from the first condition and is changed to the second condition according to the color adjustment condition. An image forming apparatus comprising: a control unit that adjusts the amount of toner adhered to the photoconductor. 3. A user adjusting means for determining a color adjusting condition is provided, and the controller adjusts the write adjusting condition by the exposing means, and the image forming signal of the dot of the edge discriminated by the discriminating means is detected by the detecting means. The first condition is changed according to the information and the color adjustment condition, and the image forming signal of the dot other than the dot discriminated by the discrimination means is different from the first condition, and the detection information and the color adjustment are performed. The image forming apparatus according to claim 1, wherein the image forming apparatus is a control unit that adjusts an amount of toner adhered to the photoconductor by changing to a second condition according to the condition. 4. The exposure intensity is changed by changing the writing condition.
The image forming apparatus according to claim 1, 2 or 3, wherein at least one of a pulse width ratio and a dot configuration is changed. 5. The image forming apparatus has at least two developing devices.
The image forming apparatus described.