JP2005202113A - Color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a variation in the linear velocity of an intermediate transfer belt and the linear velocity of transfer paper caused by the thickness of the transfer paper. <P>SOLUTION: The color image forming apparatus is equipped with: an image forming part 6 superposing a plurality of color toner images on the intermediate transfer belt 5 and forming an image; a transfer device 51 transferring the toner image carried on the intermediate transfer belt 5 to the transfer paper; a fixing device 8 fixing the toner image on the transfer paper; and a double-sided device 92 reversing the transfer paper passing through the fixing device 8 and transporting it to the transfer device 51 again. A sensor 53 having a light emitting element and a light receiving element, and reading the toner image on the belt 5 is provided, the double-sided device 92a is provided with a sensor 111 having a light emitting element and a light receiving element, and reading the image of the transfer paper, whether difference in the linear velocity exists between the intermediate transfer belt 5, and the transfer paper is found based on the result of the detection of an image for adjusting transfer paper linear velocity by the sensors 53 and 111, and the revolving speed or the like of a transfer roller in the transfer device 51, a resist roller 23 and a fixing roller in the fixing device 8 is corrected so that the difference of the linear velocity is reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a color image forming apparatus that forms a composite toner image on an intermediate transfer belt and then transfers the composite toner image onto a transfer sheet.

  In recent years, in the field of electrophotographic apparatuses, printing apparatuses capable of color printing, such as color copiers and color printers, are increasing in accordance with market demands.

  In the color electrophotographic apparatus, a single color toner image is sequentially transferred onto a transfer paper and a composite color image is recorded on a sheet, and a single color toner image is superimposed on an intermediate transfer belt to form a composite toner image. There is a system in which the toner image is transferred to record a color image on a sheet.

  Also in the recording method using the intermediate transfer belt, as described in Patent Document 1, a toner image is formed on one photoconductor, and the toner image is transferred to the intermediate transfer belt, and then the next color is printed. A toner image is formed, this toner image is transferred to an intermediate transfer belt, these steps are repeated to form a composite toner image on the intermediate transfer belt, and then transferred to transfer paper. As shown in the figure, image forming units each equipped with a developing device are arranged on a plurality of photoconductors side by side with respect to the intermediate transfer belt, and a single color toner image is formed on each photoconductor, and these single color toner images are formed. There is a system in which the image is sequentially transferred to an intermediate transfer belt to form a composite color image and then transferred to a transfer sheet.

In any of the methods, the function of superimposing and transferring the images of each color without color misregistration is a major issue, and various devices have been made to drive at a constant speed.
JP 2001-305821 A JP 2003-167456 A

  In a color image forming apparatus, the frequency of using thick paper is higher than in a monochrome image forming apparatus. In some image forming apparatuses employing an intermediate transfer belt, the linear speed of the transfer paper increases as the transfer paper thickness increases. It has been empirically said that the thickness of the transfer paper makes the diameter of the secondary transfer roller somewhat thicker and that the linear velocity is increased by being pushed by the registration roller.

  SUMMARY OF THE INVENTION An object of the present invention is to solve such problems and to reduce the variation between the linear speed of the intermediate transfer belt portion and the linear speed of the transfer paper depending on the thickness of the transfer paper.

  In order to achieve the above object, an invention according to claim 1 is directed to an image forming unit that forms a toner image of a plurality of colors, and a composite toner image formed by sequentially transferring toner images of each color formed by the image forming unit. An intermediate transfer belt portion that carries the toner image, a transfer portion that transfers the toner image carried on the intermediate transfer belt portion to the transfer paper, and the transfer paper that has passed through the transfer portion is heated to fix the toner image to the transfer paper. In a color image forming apparatus comprising a fixing unit and a double-sided unit that reverses and transfers the transfer paper that has passed through the fixing unit to the transfer unit, the color image forming apparatus includes a light emitting element and a light receiving element, and is provided on the intermediate transfer belt unit. A first sensor for reading the toner image, and a second sensor for reading an image printed on the transfer paper and having a light emitting element and a light receiving element downstream of the fixing unit in the transfer paper conveyance direction, Intermediate transfer belt part The formed transfer paper linear velocity adjustment image is read by the first sensor, the transfer paper linear velocity adjustment image fixed on the transfer paper is read by the second sensor, and the intermediate transfer belt is based on the reading results of these sensors. A controller that detects whether or not the linear velocity of the transfer portion differs from the linear velocity of the transfer paper, and drives and controls the transfer paper conveyance system so as to reduce the linear velocity difference when the linear velocity difference is detected. It is provided.

  According to a second aspect of the present invention, in the first aspect of the invention, the transfer sheet linear velocity adjustment image is composed of a plurality of reference lines perpendicular to the transfer sheet conveyance direction, and a reference based on the first sensor. The interval of the reference line in the intermediate transfer belt portion is calculated from the detection time of the line and the linear velocity of the intermediate transfer belt portion, and the reference line detection time based on the second sensor and the linear velocity of the intermediate transfer belt portion are calculated. The interval between the reference lines printed on the transfer paper is calculated, and the reference line interval on the intermediate transfer belt portion is compared with the interval between the reference lines printed on the transfer paper. And whether or not the linear velocity on the transfer paper is different.

  According to a third aspect of the invention, in the second aspect of the invention, when the interval between the reference lines formed on the intermediate transfer belt portion and the interval between the reference lines printed on the transfer paper are different, the intermediate transfer belt portion The number of rotations of the transfer roller provided in the transfer unit according to the interval of the reference line, the number of rotations of the registration roller that conveys the transfer paper to the transfer unit at a predetermined timing, and the number of rotations of the fixing roller provided in the fixing unit It is characterized by correcting in the following order.

  The invention according to a fourth aspect is the invention according to the second aspect, wherein the image forming unit is constituted by a process cartridge of Bk (black), Y (yellow), M (magenta), and C (cyan). An image is formed by a process cartridge, and a transfer sheet linear velocity adjustment image is read downstream from the fixing unit to detect the linear velocity of each process cartridge.

  According to the first aspect of the present invention, in the color image forming apparatus provided with both sides, the transfer sheet linear speed adjustment image is previously formed on the transfer sheet, and the light emitting element and the light receiving unit are disposed downstream of the intermediate transfer belt unit and the fixing unit. A sensor having an element is provided so that a transfer paper linear speed adjustment image composed of a toner image can be detected in the intermediate transfer belt section, and a transfer paper linear speed adjustment image fixed on the transfer paper can be detected downstream of the fixing section. Therefore, the linear velocity at the intermediate transfer belt portion and the linear velocity of the transfer sheet can be detected downstream of the fixing portion, and the difference between the linear velocity can be reduced.

  According to the second aspect of the present invention, the interval between the reference lines on the intermediate transfer belt portion and the interval between the reference lines on the transfer paper are compared, and the linear velocity on the intermediate transfer belt portion is different from the linear velocity on the transfer paper. Therefore, the difference between the linear velocity at the intermediate transfer belt portion and the linear velocity of the transfer paper can be detected.

  According to the third aspect of the present invention, when the interval between the reference lines of the intermediate transfer belt portion and the interval between the reference lines of the transfer paper are different, the rotational speed of the secondary transfer roller is adjusted to match the interval of the reference lines of the intermediate transfer belt portion. Since the correction operation is performed in the order of the rotation speed of the registration roller and the rotation speed of the fixing roller, even when the paper thickness of the transfer paper is different, the difference from the linear speed of the intermediate transfer belt portion can be reduced. .

  According to the fourth aspect of the present invention, when image formation is performed with each of the process cartridges of Bk (black), Y (yellow), M (magenta), and C (cyan), the linear velocity of the transfer paper is set downstream of the fixing unit. Since the detection operation is performed using the adjustment image, the linear speed on the transfer paper can be detected by the physical properties of the toner in each color process cartridge, so that the difference in the linear speed between the process cartridges can be reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a side view showing the internal configuration of the image forming apparatus of the present invention.

  In FIG. 1, an image forming unit 1 is disposed substantially at the center of the color image forming apparatus, and a paper feeding unit 2 is disposed immediately below the image forming unit 1. The paper feed unit 2 is provided with a paper feed cassette 21 at each stage, and another paper feed device 22 can be added as necessary. Above the image forming unit 1, a reading unit 3 for reading a document is disposed. A paper discharge storage unit 4 is formed on the left side in the drawing with respect to the image forming unit 1, and a recording medium (hereinafter referred to as transfer paper) on which an image is formed is discharged and stored.

  The image forming unit 1 includes a belt-shaped intermediate transfer belt 5, and four image forming units 6 are arranged around the intermediate transfer belt 5. Each image forming unit 6 includes a charging device 62 that charges the surface of the photoconductor around the drum-shaped photoconductor 61, an exposure device 7 that irradiates the photoconductor surface with laser light, and a photoconductor. A developing device 63 for visualizing the electrostatic latent image formed by exposure on the surface of the toner and a cleaning device 64 for removing and collecting the toner remaining on the photoreceptor 61 are disposed. It is configured as a process cartridge that is integrated and detachable from the main body of the image forming apparatus. As an image forming process, the toner images formed in the respective image forming units 6 are sequentially transferred onto the rotating intermediate transfer belt 5, whereby one color image is formed on the intermediate transfer belt 5.

  First, yellow (Y) toner is developed in the yellow (Y) image forming unit 6 and transferred to the intermediate transfer belt 5. Next, the magenta (M) image forming unit 6 develops the magenta toner and transfers it to the intermediate transfer belt 5. Next, in the cyan (C) image forming unit 6, cyan toner is developed and transferred to the intermediate transfer belt 5, and finally, black (BK) toner is developed and transferred to the intermediate transfer belt 5.

  On the downstream side in the circulation movement direction of the intermediate transfer belt 5 with respect to the image forming section 6, a transfer device 51 for transferring the four color toner images transferred onto the intermediate transfer belt 5 onto the transfer paper, and after the transfer, the intermediate An intermediate transfer cleaning device 52 that removes and collects toner remaining on the surface of the transfer belt 5 is disposed.

  A fixing device 8 that performs a fixing process on the transfer paper onto which the toner image has been transferred is disposed downstream of the transfer device 51 in the transfer paper transport direction. The transfer paper that has passed through the fixing device 8 is discharged and stored in the discharge storage unit 4 by the discharge roller 41 during single-sided printing. At the time of double-sided printing, the conveyance path is branched by the branching unit 91, the transfer paper is reversed via the double-sided device 92, the skew of the transfer paper is corrected by the registration roller 23, and the back side image forming operation is reached. Then, after the toner image to be the back image is transferred to the back surface of the transfer paper, it passes through the fixing device 8 and is discharged and stored in the discharge storage portion 4 by the discharge roller 41.

  In the paper feeding unit 2, unused transfer paper is stored in the paper feed cassette 21, and the bottom plate that is rotatably supported rises to a position where the uppermost transfer paper can be brought into contact with the paper feed roller. The uppermost transfer paper is fed out from the paper feed cassette 21 by the rotation of the paper feed roller and conveyed to the registration roller 23. The registration roller 23 is controlled so that the conveyance of the transfer paper is temporarily stopped, and the rotation is started at the timing when the positional relationship between the toner image on the surface of the intermediate transfer belt 5 and the leading edge of the transfer paper becomes a predetermined position.

  In the reading unit 3, in order to perform reading scanning of a document (not shown) placed on the contact glass 31, a reading traveling body 32 including a light source for document illumination and a mirror, and light from the traveling body 32 are deflected. A traveling body 33 having a mirror reciprocates. Image information scanned by the reading traveling bodies 32 and 33 is read as an image signal into a CCD 35 installed behind the lens 34. The read image signal is digitized and subjected to image processing. Based on the image processed signal, an electrostatic latent image is formed on the surface of the photoreceptor 61 by light emission of a laser diode LD (not shown) in the exposure device 7. Let it form. The optical signal from the LD in the exposure device 7 reaches the photosensitive member via a known polygon mirror or lens. Note that an automatic document feeder 36 for automatically feeding a document onto the contact glass is attached to the upper portion of the reading unit 3.

  The color image forming apparatus of this embodiment scans and reads a document as described above, digitizes it, and copies it onto transfer paper. In addition to the function as a so-called digital color copying machine, the image of the document is controlled by a control device (not shown). We assume a multi-function image forming device that has the function of a facsimile that exchanges information with a remote location and the so-called printer function that prints image information handled by a computer on transfer paper. The paper is discharged and stored in one paper discharge storage unit 4.

  Here, when the paper is branched by the branching unit 91, the transfer sheet is reversed via the double-sided device 92 and is discharged from the discharge roller 41 via the reverse roller 106 (see FIG. 3), the stack is placed in the paper discharge storage unit 4. The transferred transfer paper is in a state where the image surface is the bottom surface, and even if the processing order of the originals handled by copying, facsimile, and printer is performed from one page and printed, it is 1 The page is at the top, freeing you from work such as aligning the pages anew.

  Next, details of the double-sided device 92 will be described.

  2 is a perspective view showing the configuration of the jogger unit, FIG. 3 is a side view showing the configuration of the double-sided conveyance unit, 101 is a pair of jogger fences that can be moved in the width direction of the transfer paper, and 102 is the jogger fence. 101 is a jogger motor for driving 101, 103 is a jogger fence HP sensor, 104 is a reversing roller roller that can be moved up and down by solenoid drive, 105 is a reversing branch claw, 106 is a reversing roller, 107, 108, and 109 are reversing rollers 106 A transport roller 110 disposed downstream in the transfer paper transport direction is disposed downstream of the reversing roller 106 in the transfer paper transport direction. 1 shows a sensor having an element and a light receiving element. The jogger fence 101 is driven by a jogger motor 102, and the position of the jogger fence 101 is counted and output based on the detection position of the jogger fence 101 by the jogger fence HP sensor 103.

  The double-sided device 92 shown in FIG. 1 is provided with the jogger unit shown in FIG. 3 and the double-sided conveyance unit shown in FIG. 4, and before the transfer paper is switched back by the double-sided conveyance unit and re-conveyed, the jogger unit To align both ends of the transfer paper.

  The transfer paper that has passed through the fixing device 8 is divided into whether the paper passes through the discharge roller 41 or the double-sided device 92 by switching the branching portion 91. When the transfer path of the transfer paper is switched in the direction toward the double-sided device 92 by the branch section 91, the transfer paper is sent to the jogger section.

  A jogger operation is performed after the trailing edge of the transfer paper has passed through the reverse branching claw 105. The left and right jogger fences 101 are in a state of moving to the paper width +10 mm when the start key is ON. Then, after the trailing edge of the transfer paper passes through the reverse branching claw 105, the reversely rolled roller 104 is moved to release the contact state with the conveying roller 110, and then the jogger fence 101 is closed to the paper width −1 mm, Adjust the left and right positions of the transfer paper. Thereafter, the left and right jogger fences 101 are moved to the paper width +10 mm, the reverse roller 104 is moved by the solenoid ON, and the conveyance roller 110 is brought into contact with the transfer paper via the transfer paper to resume conveyance.

  After the resumption, the transfer paper transport path is switched to the discharge roller 41 side or the registration roller 23 side by the reverse branching claw 105. During reverse paper discharge, the conveyance path is switched to the discharge roller 41 side by the reverse branching claw 105, and during double-sided printing, the conveyance path is switched to the registration roller 23 side by the reverse branching claw 105 and passes through the reverse roller 106 and the conveyance rollers 107, 108, 109. Then, it is conveyed to the registration roller 23.

  Next, the linear velocity correction of the transfer paper will be described.

  As shown in FIG. 1, a sensor 53 having a light emitting element and a light receiving element is provided to face the intermediate transfer belt portion 5, and further downstream of the transfer device 51 and the fixing device 8 and as shown in FIG. 3. As described above, a sensor 111 having a light emitting element and a light receiving element is provided on the downstream side in the transfer paper conveyance direction with respect to the reversing roller 106.

  When performing linear velocity correction, first, a transfer paper linear velocity adjustment image composed of an unfixed toner image is formed on the intermediate transfer belt 5, and this image is read by the sensor 53, so It operates to detect a received toner image. Next, the toner image of the transfer paper linear speed adjustment image is transferred to the transfer paper and fixed by the fixing device 8, and then the transfer paper is transported to the double-sided device 92 and printed on the transfer paper. Is read by the sensor 111 to operate to detect a transfer sheet linear velocity adjustment image of the transfer sheet.

FIG. 4 is an explanatory diagram showing an example of the transfer paper linear speed adjustment image. FIG. 4A shows an image on the intermediate transfer belt, and FIG. 4B shows an image on the transfer paper after fixing. Transfer sheet linear velocity adjusting image, the intermediate transfer belt plurality of the conveying direction at right angles 5 on the reference line a _1, a _2, ......, which was formed a _n-1, a _n at regular intervals at a predetermined pitch , and the reference line _{a 1,} a 2, in the transfer paper _{......, a n-1,} the reference line corresponds to _{a n a 1, a 2,} ......, a n-1, a n is formed The

The intermediate transferring the transfer sheet linear velocity adjustment image on the belt 5 the sensor 53 detects a plurality of reference lines a ₁ by the processing means (not shown) on the basis of this detection _{result, a 2, ......, a n} -1 calculates the detection time of a _n (t), and calculates the distance between the reference line (s) the detection time (t) from the linear speed of the intermediate transfer belt unit (v). Note that represents the detection time from the detection of the reference line a _n-1 to the detection of the reference line a _n and t _n, represents the linear velocity at that time v _n, the interval of the reference line and s _n.

Similarly, printed on transfer paper reference line _{A 1,} A 2, _......, read by _{A n-1, A n} a sensor 111, and calculates the detection time T, yet the detection time T and the double-side unit 92 The reference line interval S is calculated from the linear velocity V. Incidentally, the detection time from the detection of the reference line A _n-1 to the detection of the reference line A _n represents a T _n, represents the linear velocity at that time V _n, the interval of the reference line and S _n.

  Then, the reference line interval s on the intermediate transfer belt 5 is compared with the reference line interval S on the transfer paper to detect whether the linear velocity on the intermediate transfer belt and the linear velocity on the transfer paper are different.

The linear velocity on the intermediate transfer belt 5 is obtained from the following (Equation 1).
(Equation 1)
v _n = s _n / t _n (n is the number between the reference lines)
The linear velocity on the transfer paper image can be obtained from the following (Equation 2).
(Equation 2)
V _n = S _n / T _n (n is a number between reference lines)
Here, since the linear velocity Vn of the transfer paper through the intermediate transfer belt 5 linear velocity on v _n and the sensor 111 to the same, the detection time t _n and the detection time T _n is the same, for example, transferring cardboard as in the case of using as a paper, if the linear velocity v _n and the linear velocity V _n of the transfer sheet of the intermediate transfer belt 5 are different, the t _n ≠ T _n.

If a portion where the detection time t _n is different from the detection time T _n is detected, the interval s _n between the reference lines of the intermediate transfer belt 5 and the interval S _n between the reference lines of the transfer paper obtained by arithmetic operation are different.

If the interval S _n of the intermediate transfer and spacing s _n of the belt 5 of the reference beam transfer sheet of the reference line is different, fit spacing s _n of the reference line of the intermediate transfer belt 5, the rotation speed of the secondary transfer roller in the transfer device 51 Then, the correction operation is performed in the order of the rotation speed of the registration roller 23 and the rotation speed of the fixing roller in the fixing device 8.

  In the image forming apparatus of FIG. 1, a transfer sheet linear velocity adjusted image is formed in each of the image forming units 6 of Bk (black), Y (yellow), M (magenta), and C (cyan). Since the operation for detecting the transfer paper linear velocity adjustment image is performed downstream, the linear velocity on the transfer paper can be detected based on the physical properties of the toner in each color process cartridge constituting the image forming unit 6. The linear velocity difference can be reduced.

  The present invention can be used in the field of a color image forming apparatus that forms a composite toner image on an intermediate transfer belt and then transfers the composite toner image to transfer paper.

1 is a side view showing an internal configuration of an image forming apparatus according to an embodiment of the present invention. The perspective view which shows the structure of a jogger part. Side view showing the configuration of the double-sided transport unit Explanatory drawing which shows an example of a transfer paper linear velocity adjustment image

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image formation part 2 Paper feed part 3 Reading part 4 Discharge storage part 5 Intermediate transfer belt 6 Image formation part 7 Exposure apparatus 8 Fixing apparatus 23 Registration roller 51 Transfer apparatus 53,111 Sensor 101 Jogger fence 104 Reversed roller roller 106 Reverse roller 107, 108, 109, 110 Conveying roller

Claims (4)

  An image forming section for forming a toner image of a plurality of colors, an intermediate transfer belt section for supporting a composite toner image formed by sequentially transferring the toner images of the respective colors formed by the image forming section, and the intermediate transfer belt section. A transfer unit that transfers the toner image to the transfer paper, a fixing unit that heats the transfer paper that has passed through the transfer unit to fix the toner image on the transfer paper, and a transfer paper that has passed through the fixing unit is reversed. In a color image forming apparatus including a double-sided portion that is re-conveyed to the transfer unit, a first sensor that includes a light-emitting element and a light-receiving element and reads a toner image on the intermediate transfer belt unit is provided, and the fixing unit On the other hand, a second sensor that has a light emitting element and a light receiving element and reads an image printed on the transfer paper is provided downstream of the transfer paper conveyance direction, and the transfer paper linear velocity adjustment image formed on the intermediate transfer belt portion is Read to the first sensor Whether or not the linear velocity of the intermediate transfer belt portion and the linear velocity of the transfer paper are different based on the reading results of the sensors by causing the second sensor to read the transfer paper linear velocity adjustment image fixed on the transfer paper. A color image forming apparatus comprising: a control unit that drives and controls a transfer paper conveyance system so as to reduce the linear velocity difference when the linear velocity difference is detected.   The transfer paper linear speed adjustment image is composed of a plurality of reference lines perpendicular to the transfer paper transport direction, and the intermediate transfer is performed based on the reference line detection time based on the first sensor and the linear speed of the intermediate transfer belt unit. Calculating the interval between the reference lines in the belt portion, calculating the interval between the reference lines printed on the transfer paper from the detection time of the reference line based on the second sensor and the linear velocity of the intermediate transfer belt portion; Detecting whether or not the linear velocity on the intermediate transfer belt portion and the linear velocity on the transfer paper are different by comparing the interval between the reference lines in the transfer belt portion and the interval between the reference lines printed on the transfer paper. The color image forming apparatus according to claim 1, wherein:   When the interval between the reference lines formed on the intermediate transfer belt portion and the interval between the reference lines printed on the transfer paper are different, the transfer roller provided in the transfer portion according to the interval between the reference lines of the intermediate transfer belt portion 3. The color according to claim 2, wherein the number of rotations is corrected in the following order: rotation number of a registration roller that conveys transfer paper to the transfer unit at a predetermined timing, and rotation number of a fixing roller provided in the fixing unit. Image forming apparatus.   The image forming unit is constituted by process cartridges of Bk (black), Y (yellow), M (magenta), and C (cyan), each of the process cartridges forms an image, and a transfer sheet downstream from the fixing unit. The color image forming apparatus according to claim 2, wherein a linear velocity of each process cartridge is detected by reading a linear velocity adjustment image.

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