JPH096073A - Image forming device - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide an image forming apparatus that is a simple apparatus in which curl correction is surely performed according to the curl amount of transfer paper and image formation is performed. In an image forming apparatus capable of transferring and fixing a toner image onto the same surface or the back surface of a transfer paper on which the toner image is transferred and fixed at least once more,
Transfer means 3 for transferring the toner image formed on the transfer paper 2 to the transfer paper 2
A fixing means 4 for fixing the toner image transferred onto the transfer paper 2 by the transfer means 3, and a curl amount of a predetermined amount or more of the transfer paper 2 on which the toner image is fixed and conveyed by the fixing means 4. Curl amount detecting means 5 for detecting the above, a decurling means 6 for interlocking with the curling amount detecting means 5 for performing a decurling operation for contacting with or separating from the transfer paper 2, and the above-mentioned de-curling means 6 for carrying the curling amount. And a switching means 7 for switching the transfer direction of the transfer paper 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, a scanner, or a multi-function machine having these functions together, which has the toner image transferred and fixed on the same surface or the back surface. Further, the present invention relates to an image forming apparatus capable of transferring and fixing a toner image at least once.

[0002]

2. Description of the Related Art As a conventional image forming apparatus, for example, there is an electrophotographic copying machine shown in FIG. 3, in which a transfer paper 102 fed from a paper feeding section 100 includes a plurality of drum-shaped photosensitive members 101 and a belt. Of the toner image on the photoconductor after being sent to the transfer means 103 and then separated, or heated while being pressurized by the fixing means 104, and transferred to various rollers such as the conveyance roller 109. After being wound or the like, the transporting direction is changed by the switching unit 107 and is transported to the paper discharging unit 108 or the double-sided unit 110.
Curling habits are often formed. The curl habit formed on the transfer paper 102 in this manner causes a transfer failure, or causes a tip break or a jam when the amount of curl is large.

Various devices and methods have been proposed to prevent these problems, and these will be described below. That is,
First, by providing detection means for detecting the presence or absence of curl of the transfer paper in the conveyance path of the copying machine, the direction of the curl of the transfer paper, the amount of curl of the transfer paper, etc., and a curl removing means on the downstream side of the detection means. A technique is known in which the curl removing means is controlled by a detection signal of the detecting means to remove the curl of the transfer paper (see Japanese Patent Laid-Open No. 56-48343). A curl habit forming unit composed of a metal roller and an elastic roller is arranged in a conveyance path for conveying the transfer sheet after the first fixing in the image forming apparatus to the second and subsequent transfer steps, and the sheet is fixed on both sides. A technique is also known in which a paper is passed through the pressure contact surface of a roller each time so that the roller comes into a curled state in which it is separated from the photosensitive drum before the second and subsequent transfer steps (Japanese Patent Laid-Open No. 62-2559).
62).

In an image forming apparatus such as a copying machine, a heat pipe can be brought into contact with a transfer paper so that a back curl is likely to occur to eliminate the curl toward the image surface side, and a temperature from a temperature detection sensor is used. A technique is also known in which a signal is compared with a set temperature to variably control the air volume to cause a decal (see JP-A-4-344663). In a copying machine or the like, there is also known a technique in which the guide plate is moved and retracted from the area so that the curled transfer paper is not caught by the guide plate and jammed (Japanese Patent Laid-Open No. 4-39252). See the bulletin). However, in any of the above image forming apparatuses, the curl correction amount is continuously adjusted according to the curl amount of the transfer paper, or the decurling operation is performed independently of the curl amount, and the curl amount of the transfer paper is changed. Accordingly, since the guide plate is moved from that area and retracted, there is a problem that a stable decurling operation is not performed according to the curl amount of the transfer sheet or the apparatus becomes complicated.

[0005]

In the above-mentioned conventional image forming apparatus, the curl correction amount is continuously adjusted according to the curl amount of the transfer paper, or the decurling operation is performed regardless of the curl amount. Alternatively, since the guide plate is moved and retracted from the area according to the curl amount of the transfer paper, stable decurling operation is not performed according to the curl amount of the transfer paper, or the device becomes complicated. There was a problem.

[0006]

SUMMARY OF THE INVENTION Therefore, the present invention is to solve such a problem. That is, it is an object of the present invention to provide an image forming apparatus which is a simple apparatus in which curl correction is surely performed according to a curl amount of a transfer paper or more and image formation is performed.

[0007]

In order to achieve the above object, the present invention according to claim 1 further transfers a toner image onto the same surface or the back surface of a transfer paper on which a toner image is transferred and fixed at least one more time. An image forming apparatus capable of fixing the toner image formed on the photoconductor to a transfer paper, and a fixing means for fixing the toner image transferred to the transfer paper by the transfer means. A curl amount detecting unit that detects a curl amount of the transfer paper, which is fixed and a toner image is conveyed by the fixing unit, and abutting or separating from the transfer paper in cooperation with the curl amount detecting unit. The most main feature is that the image forming apparatus has a decurling means for performing the decurling operation and a switching means for switching the carrying direction of the transfer paper carried from the decurling means. A second aspect of the present invention is characterized in that, in the image forming apparatus according to the first aspect, the curl amount detecting means is configured to be able to detect two or more types of curl amounts which are equal to or more than a predetermined amount, separately. .

A third aspect of the present invention is characterized in that, in the image forming apparatus according to the first or second aspect, at least one of the decurling means is a pair of rollers including heating rollers. . The invention of claim 4 is
The image forming apparatus according to claim 1, 2 or 3, wherein the decurling unit operates in conjunction with the curl amount detecting unit that detects a curl amount of the transfer paper which is equal to or larger than a predetermined amount, and The main feature is that a decurling operation is performed in contact with the transfer paper when passing.

According to a fifth aspect of the present invention, in the image forming apparatus according to the first, second, third, or fourth aspect, the decurling means detects the curl amount of the transfer paper which is more than a predetermined amount by the curl amount detecting means. The main feature is that the heating temperature is variable. The present invention according to claim 6 is the image forming apparatus according to claim 1, 2, 3, 4 or 5,
A main feature of the switching means is that the transfer paper, which has detected a curl amount larger than a predetermined amount by the curl amount detecting means, is switched to a conveyance direction in which the transfer paper is discharged to a discharge portion.

[0010]

According to the first aspect of the present invention, in the image forming apparatus having the above-mentioned structure, the curl amount detecting means for detecting the curl amount of the transfer paper on which the toner image is fixed and conveyed is decurled. Since the transfer sheet is conveyed in the conveying direction by the switching section after the decurling operation of contacting or separating the transfer sheet with respect to the transfer sheet, the curl is surely corrected according to the curl amount of the transfer sheet. It is possible to provide an image forming apparatus having a simple structure for performing image formation.

According to another aspect of the present invention, the decurling means interlocking with the curl amount detecting means for detecting the curl amount of the transfer paper on which the toner image is fixed and conveyed by distinguishing it into two or more types. After the contact or separation decurling operation, the switching means is configured to convey the transfer paper in the conveying direction, so that the curl is surely corrected according to a plurality of curl amounts of the transfer paper which are equal to or more than a predetermined value. Stable image formation It is possible to provide an image forming apparatus having a simple structure for performing the above.

According to a third aspect of the present invention, there is provided a decurling means composed of a pair of rollers, at least one of which is a heating roller, in conjunction with the curl amount detecting means for detecting the curl amount of the transfer paper which is more than a predetermined value. After the decal operation of contacting or separating from the transfer paper, the switching means conveys the transfer paper in the conveying direction.
It is possible to provide the image forming apparatus having a simple structure in which the curl correction is variably and reliably performed according to the curl amount of the transfer paper which is equal to or larger than a predetermined value.

According to another aspect of the present invention, the decurling means interlocking with the curl amount detecting means for detecting the curl amount of the transfer paper or more is brought into contact with the transfer paper when the transfer paper having the curl amount or more is passed. After the decurling operation is performed, the switching means conveys the transfer paper in the conveying direction, so that the curl correction is surely performed corresponding to the predetermined curl amount of the transfer paper and stable image formation is performed. An image forming apparatus having a simple structure can be provided.

According to a fifth aspect of the present invention, there is provided decurling means for changing the heating temperature by detecting a curl amount of the transfer paper which is larger than a predetermined amount in association with a curl amount detecting means which detects a curl amount of the transfer paper which is larger than a predetermined amount. Since the decurl means is configured to carry out the decurl operation for contacting or separating the transfer sheet and then the transfer means is configured to convey the transfer sheet in the conveying direction, it is possible to more reliably and variably according to the curl amount of the transfer sheet. It is possible to provide an image forming apparatus having a simple structure in which curl correction is performed and image formation is performed.

According to a sixth aspect of the present invention, after the decurling means interlocking with the curl amount detecting means for detecting the curl amount of the transfer paper which is greater than or equal to a predetermined value makes contact with or separate from the transfer paper, transfer is performed by the switching means. Since the paper is conveyed in the direction in which it is ejected to the paper ejection section, even if the curl amount of the transfer paper at the time of the predetermined amount or more during double-sided copying exceeds the capacity of the decurling means, the curl can be surely corrected by the manual operation. It is possible to provide an image forming apparatus having a simple structure for performing image formation.

[0016]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration explanatory view of an electrophotographic color copying machine which is an example of an image forming apparatus of the present invention.
The toner images formed on the surfaces of the plurality of drum-shaped photoconductors 1 arranged in parallel with each other are sequentially transferred onto the transfer paper 2 conveyed by the transfer belt 3a. In this image forming apparatus, the toner images are transferred onto one side. The toner image can be transferred and fixed at least once more on the same surface or the back surface of the transfer paper 2 which has been fixed. Color image reading unit 1
Reference numeral 1 forms a read image of a document (not shown) on the contact glass 12 on a color sensor 11d via an illumination lamp 11a, a mirror group 11b, and an imaging lens 11c.
The color image information of the original is, for example, blue (Blue).
e), green and red are read for each color separation and converted into an electrical image signal.

Blue, green, and red (R) obtained by the color image reading section 11 are obtained.
ed) based on the color separation image signal intensity level, color conversion processing is performed by an image processing unit (not shown), and black (B
rack, cyan, magenta (Mage)
nta) and yellow (Yellow) color image data are obtained. Then, by the image forming unit 13 described next, black (Black), cyan (Cyan),
Magenta, Yellow (Yello)
w) is visualized, and these are superposed to form a four-color color image.

Optical writing optical units 13a1 to 13a
A drum-shaped photoconductor 1 4 converts the color image data from the color image reading unit 11 into an optical signal and performs optical writing corresponding to the color original image of the original.
An electrostatic latent image is formed on a to 1d. The photoconductor 1a rotates clockwise in the direction of arrow A in the figure, but around it, the black (Black) developing device 13b1 and the transfer belt 3a are provided.
A cleaning unit including a pre-cleaning static eliminator (not shown), a static eliminator lamp, a charger, a potential sensor, and the like are arranged.

The photosensitive member 1b rotates clockwise in the direction of arrow A shown in the drawing, around which a cleaning unit including a cyan developing device 13b2, the transfer belt 3a and a pre-cleaning static eliminator (not shown), A static elimination lamp, a charger, a potential sensor, etc. are arranged. The photoconductor 1c rotates in the clockwise direction indicated by the arrow A in the drawing, but around the photoconductor 1c, a magenta developing device 13b is provided.
3. A cleaning unit including the transfer belt 3a and a pre-cleaning static eliminator (not shown), a static eliminator lamp, a charger, a potential sensor and the like are arranged. The photoreceptor 1d is
Although it rotates clockwise in the direction of arrow A in the figure, around it, a yellow developing unit 13b4, a cleaning unit including the transfer belt 3a and a pre-cleaning static eliminator (not shown), a static erasing lamp, a charger, and a potential sensor. Etc. are arranged.

Black developing unit 13b1,
Cyan developing device 13b2, magenta (Mag)
enta) developing device 13b3, yellow
The developing device 13b4 and the like rotate a developing sleeve (not shown) for rotating the brush of the developer in contact with the surfaces of the photoconductors 1a to 1d for developing the electrostatic latent image, and for pumping and stirring the developer. The development paddle (not shown) and a developer concentration detection sensor (not shown) that detects the concentration of the developer are included. When the copy operation is started, the color image reading unit 11 starts black (Bla
ck) The reading of the image is started, and the optical writing optical unit 13 using the laser light is started based on the image data.
The latent image formation by a is started.

In order to allow the latent image of the black image to be developed from the leading end portion, before the leading end portion of the latent image reaches the developing position of the black developing device 13b1, the developing sleeve (not shown) starts to rotate and the developer The ears are raised, and the latent image of the black image is developed with the toner of the black developer. After that, the developing operation of the latent image area of the black image is continued, but when the trailing edge of the latent image area passes the black developing position, the developer on the developing sleeve (not shown) is quickly cut off,
Development is inoperative.

The black toner image formed on the photoconductor 1a is transferred onto the transfer belt 3a at the same speed as the photoconductor 1.
Transfer is performed by applying a predetermined bias voltage to the upper transfer paper 2 while the photoconductor 1 and the transfer paper 2 are in contact with each other. The transfer paper 2 on which the black toner image formed on the photoconductor 1a is transferred is conveyed in the direction of the arrow B shown in the drawing, and is transferred at a predetermined timing as in the case of transferring the black toner image formed on the photoconductor 1a. While maintaining the above, the cyan (Cyan) toner image on the photoconductor 1b, the magenta toner image on the photoconductor 1c, and the yellow (yellow) toner image on the photoconductor 1d are sequentially transferred.

The developing and transferring operations are the same as those described for the black toner image formed on the photoconductor 1a, and the description will be omitted. After the transfer, the transfer paper 2 is heated by the fixing means 4 while being pressed and melted and fixed. Immediately after the fixing unit 4, a curl amount detecting unit 5 that detects a curl amount of the transfer sheet 2 that is equal to or larger than a predetermined amount, and the transfer sheet 2 that is linked with the curl amount detecting unit 5
The decurling means 6 for performing the contact and separation decurling operations are sequentially arranged. Then, the transfer paper 2 is surely decurled or not decurled by the decurling means 6 according to the amount of curl detected by the curl amount detecting means 5. The decurled transfer paper 2 is discharged by the switching claws of the switching means 7 to the discharging means 8
The paper is conveyed to and discharged, and is stored on the paper discharge tray.

Next, a case will be described in which the toner image is transferred and fixed not only on the front surface of the transfer paper 2 but also on the back surface thereof. In this case, the transfer paper 2 is transferred to the double-sided means 10 after the toner image is transferred onto the surface thereof and fixed by the fixing means 4 and then the conveying direction is switched by the switching claw of the switching means 7. However, when the curl amount detecting means 5 detects a curl amount of a predetermined amount or more, the switching claw 7 switches to discharge the sheet to the sheet discharging means 8 instead of the conveying direction of the double-sided means 10. Therefore, when the curl amount of the transfer paper 2 exceeds the decurling ability of the decurling means 6, the curl is manually corrected because the paper is conveyed not to the conveying direction of the double-sided means 10 but to the paper discharging means 8 and discharged. Manual double-sided copy can be obtained, and stable double-sided copy without jam is possible.

FIG. 2 is a schematic diagram showing a configuration example of the curl amount detecting means 5, which is arranged on the downstream side of the fixing means 4 in the conveying direction C of the transfer paper 2 and is a non-contact combination of the light emitting portion 5a and the light receiving portion 5b. Thus, the curl amount of the transfer paper 2 which is larger than a predetermined amount is detected. Therefore, by arranging a plurality of n combinations of the light emitting section 5a and the light receiving section 5b, the transfer paper 2
It is possible to distinguish two or more types of n curl amounts above a predetermined value, and moreover, it is possible to reliably detect this with a simple device.

The decurling means 6 comprises a pair of rollers 6a.
And a lower roller 6a2 is provided with heating means for the upper roller 6a1, and a toner image is fixed by the fixing means 4 and the transfer paper 2 is conveyed in the direction of arrow C in the figure.
The decal operation of contact and separation is performed. Here, the contact means that the rollers 6a1 and 6a2 are in pressure contact with each other to perform the decurling operation, and the separation means that the rollers are separated from each other and the decurling operation is not performed. Therefore, at least one of the rollers can be moved toward and away from the other roller. Alternatively, both rollers may be kept in pressure contact with each other while the lower roller generates heat during decurling and does not generate heat during non-decal.

That is, the decurling operation of the decurling means 6 is interlocked with the curling amount detection means 5 detecting the curling amount of a predetermined amount or more, and the curling amount detection means 5 detects the curling amount of the transfer paper 2 or more. At this time, feedback is applied by the curl amount detecting means 5 to reheat and the decurling operation is turned on and abutted, or the decurling operation is turned off to separate.

The decurling means 6 detects n or more curl amounts of the transfer paper 2 by the curl amount detecting means 5 which is a combination of the n light emitting portions 5an and the light receiving portions 5bn arranged side by side and feeds them back. Takes a
The heating temperature of the heating means of the lower roller 6a2 of the pair of rollers 6a is varied so that the decurling operation is performed in accordance with a predetermined curl amount. When the curl amount is less than the specified amount (including when there is no curl)
, The decal operation is not performed.

[0029]

As described above, according to the first aspect of the invention, the curl amount detecting means for detecting that the transfer paper on which the toner image has been transferred and fixed has a predetermined curl or more. , Decurling means for performing a decurling operation interlocking with both the curling detecting means, and after the decurling means makes contact or separation decurling operation with respect to the transfer paper,
Since the transfer sheet is conveyed in the conveying direction by the switching means, the curl can be surely corrected according to the curl amount of the transfer sheet which is equal to or more than a predetermined value, and the device configuration can be simplified.

According to the second aspect of the invention, the decurling means interlocking with the curl amount detecting means for detecting the curl amount of the transfer paper by distinguishing it into two or more types performs the decurling operation of contacting or separating from the transfer paper. Since the transfer sheet is conveyed in the conveying direction later by the switching means, the curl can be surely corrected according to a plurality of curl amounts which are equal to or larger than a predetermined value.
The device configuration is also simple.

According to the third aspect of the present invention, a pair of rollers, at least one of which is a heating roller, is interlocked with the curl amount detecting means for detecting the curl amount of the transfer paper on which the toner image is fixed and conveyed and which is greater than a predetermined value. Since the decurling means constituted by the above is provided and the decurling means makes contact with or separates from the transfer sheet and then the transfer sheet is conveyed in the conveying direction by the switching means, it is possible to prevent the transfer sheet from exceeding a predetermined size. The curl correction is variably and reliably performed according to the curl amount. The device configuration is also simple.

According to the invention of claim 4, there is provided a decurling means interlocking with a curl amount detecting means for detecting the curl amount of the transfer paper on which the toner image is fixed and conveyed, and the decurling means is above the predetermined amount. When the transfer paper with a curl amount of the above is passed, the transfer paper is conveyed in the conveying direction by the switching means after the decurling operation of abutting against the transfer paper is performed, so that the curl amount of the transfer paper is greater than the predetermined amount. As a result, stable image formation is performed in which curl correction is reliably performed.

According to the fifth aspect of the invention, the curl amount of the transfer paper is detected in cooperation with the curl amount detecting means for detecting the curl amount of the transfer paper on which the toner image is fixed and conveyed. Since the decal means for changing the heating temperature is provided by the decal means, and the decal means makes contact or separation decal operation with respect to the transfer paper, the transfer paper is conveyed in the conveying direction by the switching means. The curl correction is variably and more reliably performed according to the curl amount. The device configuration is also simple.

According to the sixth aspect of the present invention, a decurling unit is provided which is interlocked with a curl amount detecting unit for detecting a curl amount of the transfer paper on which the toner image is fixed and conveyed, and the decurling unit is provided. Since the transfer sheet is conveyed in the conveyance direction in which the transfer sheet is discharged to the sheet discharge section after the contact or separation decurling operation is performed, the curl amount of the transfer sheet at the predetermined amount or more during double-sided copying is Even when the capability of the decurling means is exceeded, the curl is surely corrected manually to form an image. The device configuration is also simple.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating an outline of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged perspective view illustrating a main part of the image forming apparatus according to the exemplary embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating an outline of a conventional image forming apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photoconductor, 1a-d ... Photoconductor, 2 ... Transfer paper, 3 ... Transfer means, 3a ... Transfer belt, 4 ...
.Fusing means, 5 ... curl amount detecting means, 5a1-n
..Light emitting portions, 5b1 to n ... Light receiving portions, 6 ... Decal means, 6a ... A pair of rollers, 6a1 ... Upper roller, 6a2 ... Lower roller, 7 ... Switching means, 8 ... Paper discharging means, 9 ... Conveying rollers, 10.
..Double-sided means, 11 ... Color image reading section, 11a
... Illumination lamp, 11b ... Mirror group, 11c ...
.Imaging lens, 11d ... color sensor, 12 ...
Contact glass, 13 ... Image forming unit, 13a ...
-Optical writing unit, 13a1 to 4 ... Optical writing unit, 13b ... Developing device, 13b1 ... Black developing device, 13b2 ... Cyan developing device, 13b3 ...
・ Magenta developer, 13b4 ... Yellow developer, 1
01 ... photoconductor, 101a-d ... photoconductor, 102
... Transfer paper, 103 ... Transfer means, 103a ...
Transfer belt, 104 ... Fixing device, 107 ... Switching device, 108 ... Paper discharging device, 109 ... Conveying roller, 110 ... Double-sided device.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yasuhiro Kodaira 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (6)

[Claims] 1. An image forming apparatus capable of transferring and fixing a toner image at least once more on the same surface or the back surface of a transfer paper which has undergone transfer and fixing of the toner image. Transfer means for transferring the toner image onto the transfer paper, fixing means for fixing the toner image transferred onto the transfer paper by the transfer means, and transfer processing after the toner image is fixed by the fixing means A curl amount detecting unit that detects a curl amount of a predetermined amount or more of the paper, a decurling unit that interlocks with the curl amount detecting unit and performs a decurling operation of contacting or separating from the transfer sheet, and is conveyed from the decurling unit. An image forming apparatus, comprising: a switching unit that switches a transfer direction of the transfer paper. 2. The image forming apparatus according to claim 1, wherein
The image forming apparatus, wherein the curl amount detecting means has a configuration capable of detecting two or more types of curl amounts separately. 3. The image forming apparatus according to claim 1, wherein the decurling unit includes a pair of rollers, at least one of which is a heating roller. 4. The image forming apparatus according to claim 1, 2 or 3, wherein the decurling unit is interlocked with the curl amount detecting unit for detecting a curl amount of the transfer paper which is equal to or more than a predetermined amount. 2. An image forming apparatus, wherein a decurling operation of contacting the transfer sheet is performed when the transfer sheet passes. 5. The image forming apparatus according to claim 1, 2, 3 or 4, wherein the decurling means changes a heating temperature when the curl amount detecting means detects a curl amount of a predetermined amount or more. An image forming apparatus characterized by. 6. The image forming apparatus according to claim 1, 2, 3, 4, or 5, wherein the switching unit transfers the transfer paper, which has been detected by the curl amount detecting unit to a curl amount equal to or more than a predetermined amount, to a paper output unit. An image forming apparatus characterized by switching to a conveying direction for discharging a sheet.