JP3288341B2 - Image forming device - Google Patents

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 and a laser beam printer utilizing an electrophotographic technique.

[0002]

2. Description of the Related Art FIGS. 7 and 8 show a conventional color image forming apparatus. In the figure, image forming units PM, PC, P for forming images of magenta, cyan, yellow, and black, respectively.
Y and PK are arranged along the transfer material conveying device 60.
Each of the image forming units PM, PC, PY, and PK has the same configuration, and one of the last MCYKs in the code representing each image forming unit is listed next to the numeral code in each of its constituent members. FIG. 8 shows the image forming unit PK. Therefore, in the description common to each image forming unit, the same reference numerals as those at the end of the image forming unit are omitted.

A primary charging device 2 for uniformly charging the surface of the photosensitive drum 1, a scanning optical device 3 including a laser light source, a collimator lens, and a polygon mirror are provided around the photosensitive drum 1 rotating in the direction of the arrow shown in FIG. A surface potential detector 11 for detecting the potential of the surface of the drum 1; a developing device 4 for converting a latent image on the photosensitive drum 1 into a visible image;
A transfer charger 7 for applying an electric charge for transferring the visible image to a transfer material sent from the right to the left in the figure with 0, a cleaning device 5 for cleaning residual toner on the photosensitive drum 1 after the transfer, and the like are arranged. Have been. The transfer material transporting device 60 includes the driving pulley 6
a, a conveyor belt 6 is stretched between the driven pulleys 6b as a transfer material carrying sheet of a dielectric endless belt.

[0004] As shown in FIG. 8, the surface potential detector 11 is connected to a controller 100 via a surface potential meter 14. A test pattern reading device 12 that reads a test pattern 22 such as a registration mark or a test patch provided on the conveyor belt 6 is provided. The reading device 12 includes a reading sensor 12a, for example, a CCD or the like, and an imaging lens 12c that is reflected by the test pattern 22 and reflected by the test pattern 22.
Lamp 1 illuminating the test pattern 22 at right angles to the test pattern 22 for sending image light of the test pattern to the CCD
2b. The test pattern read by the reading sensor 12a is converted into a density signal via the density conversion circuit 16 and input to the controller 100.

[0005] The controller 100 manages each of the above detection information and controls each image forming condition. Next, the order of image formation will be described. A primary charger 2 is uniformly applied to the photosensitive drum 1.
Charging is performed. Next, a light image is exposed by the scanning optical device 3, and this light image is based on a signal which has been scanned and read by a document reading scanner (not shown) and subjected to image processing. Exposure of this light image causes the photosensitive drum 1
Is formed with a potential latent image. This latent image is subsequently developed with toner by the developing device 4 to become a visible image. Thereafter, the toner image is transferred by the transfer charger 7 onto a transfer material carried on the transport belt 6 and moved in the direction of the arrow in the figure. A full-color image in which the above steps are repeated in the stations PM, PC, PY, and PK for magenta, cyan, yellow, and black is obtained. On the other hand, from the controller 100,
The output of the test pattern is instructed at predetermined intervals, and the same image as the test pattern is formed on the photosensitive drum 1 in the same manner as in the above-described process.
Formed on the transfer belt 6 without transferring the transfer material.
The test pattern is read by the test pattern reading device 12 on the conveyor belt 6 and the density is detected. The detected toner density is processed by the controller 100 and is processed by an image forming unit such as a charging potential.
It controls the LUT, toner density, transfer current and the like. Further, the stability of the registration is improved by using a method of detecting a color shift of each color by detecting a registration mark and correcting the optical system by an actuator.

For example, a plurality of image forming units PM,
In a color image forming apparatus having a PC, PY, and PK, the test pattern reading device 12 has means for correcting a deviation of each color by controlling a writing start timing and a reflection mirror (not shown) by a microcomputer built in the main body. Since the toner to which the test pattern 22 has been transferred reflects infrared light, the test pattern reading device 12
The visible light cut filter 12d is provided as shown in FIG. 1, and the diffuse reflection light of the toner image by the pair of illumination lamps 12b on both sides thereof is read by a reading sensor 12a such as a CCD through a lens 12c.

At this time, the CCD output V is as shown in FIG.
In FIG. 4, CL is the optical axis of the lens 12c. Also,
The illumination lamp 12b is installed obliquely so that the regular reflection light from the conveyor belt 6 is not directed to the reading sensor 12a.
The transport belt 6 is made of, for example, PET, polyurethane, PVDF
A transparent or translucent resin film that transmits infrared light is used. Therefore, the position of the test pattern 22 is detected from the difference between the diffuse reflection light of the test pattern 22 and the reflection light of the transport belt 6.

[0008]

However, in the above-described conventional technique, the surface of the pulley for holding the transport belt 6 is notched when processing the pulley, dust adheres to the pulley, and various belt backup members (for example, When the back surface of the conveyor belt 6 is damaged by the conveyor belt support member 51) in FIGS. 9 and 10, the following problems occur. As shown in FIG. 5, in addition to the diffusely reflected light of the test pattern 22, specularly reflected light due to a scratch 6x on the back surface of the transport belt 6 is read by the reading sensor 12a.
The output of the reading sensor 12a (CCD) at that time is as shown in FIG. The output V22a due to the reflected light of the flaw 6x other than the output V22 corresponding to the test pattern 22 is generated. The CCD output changes depending on the degree of flaw 6x, but the microcomputer built-in the flaw 6
Since the discrimination between x and the test pattern 22 cannot be determined, if the scratch 6x is read and controlled, the color shift may become more severe.

Further, in this configuration, since only the transfer material and the photosensitive drum are in contact with the surface of the conveyor belt 6, the surface of the conveyor belt 6 is relatively difficult to be damaged. It will have an adverse effect.

Basically, in order to read the test pattern 22, erroneous reading is not performed as the difference between the reflected light of the toner by the light of the illumination lamp 12b and the reflected light of the conveying belt 6 is large. Since the color toner generally used at present is of a type that reflects infrared light, it is desirable to make the reflected light of the conveyor belt 6 zero. Therefore, the conventional conveyor belt 6 uses a transparent or translucent resin. The reflectance is reduced by increasing the transmittance for the light of the illumination lamp 12b using a film. However, in the case of the resin film of such a material, when the scratch 6x occurs due to the above-described cause, the resin film is likely to be whitish in appearance. In other words, the damaged portion means that the transmittance for light decreases, and the reflected light increases accordingly. The same is true for infrared light, and there is a drawback that a scratch on the conveyor belt 6 tends to increase the reflectance instead of lowering the transmittance.

Therefore, in consideration of the fact that the transport belt 6 having the increased transmittance as described above smoothly rotates as the transport belt, the hardness of the material is not increased to prevent scratches, and it is difficult to select the material. There is a disadvantage that the life of the conveyor belt 6 is significantly reduced only to prevent erroneous reading detection.

[0012]

The problem to be solved by the present invention is solved by the following means.

According to a first aspect of the present invention, a test pattern provided on a transport belt is used for testing the test pattern of the transport belt.
An image forming apparatus that has a reading unit that optically reads from the side on which the pattern is provided , and controls the image forming unit based on information obtained by the reading unit.
The reading means illuminates the test pattern.
Light means for receiving reflected light from the test pattern
An image forming apparatus , comprising: a light receiving unit; and wherein the transport belt has an absorptivity for infrared light greater than a transmittance.

According to a second aspect of the present invention, the transport belt includes:
The image forming apparatus according to the first aspect, wherein the image forming apparatus contains carbon.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

The first and second embodiments are to prevent the irradiation light of the illumination lamp of the reading device used for registration or the like from being reflected on the reading sensor due to the damage of the transport belt.

First Embodiment FIG. 1 is a schematic vertical sectional view of a first embodiment in which the present invention is applied to an electrophotographic color copying machine. In the figure, FIG.
The same parts as those described above are denoted by the same reference numerals, and description thereof will be omitted. A sheet feeding device 65 is provided on one side in the copying machine main body 30, that is, on the right side in FIG. 1, and a transfer material discharge port 24 is provided on the opposite side on the left side in FIG. The fixing device 8 is disposed inside and adjacent to the discharge port 24. The copier body 3
A driven pulley 6b is provided near the paper feeding device 65 in FIG. 0, and a driving pulley 6a is provided near the fixing device 8, and an endless conveying member, for example, between these pulleys 6a and 6b. The transport belt 6 is wound. Below the drive pulley 6a, a tension pulley 6d is provided from the circumferential side of the transport belt 6 to contact the transport belt 6 to freely adjust the pulling force of the transport belt.

The paper feeding device 65 includes a paper feeding cassette 61 that is detachable from the copying machine main body 30, a rotatable paper feeding roller 62 provided at a mounting portion of the copying machine main body 30 where the paper feeding cassette 61 is mounted, Paper feed guide 6 for guiding transfer material P sent into copying machine body 30 by paper roller 62
3. A registration roller pair 64 that receives the transfer material P guided by the paper feed guide 63 and feeds the transfer material P onto the conveyor belt 6 on the driven pulley 6b side at a predetermined timing.
The sensor includes a sensor (not shown) that outputs a predetermined signal when detecting the leading end of the transfer material P moving in the paper feed guide 63. The paper feeding device 65 performs a function of placing the transfer material P on the conveyor belt 6 from the driven pulley 6b side. The transfer material discharge port 24 is provided with a discharge tray 117 that is detachable from the copying machine main body 30.

Each of the image forming units PM, PC, PY, and PK
The sensors 66M, 66
C, 66Y, and 66K are provided, and these sensors detect when the leading end of the transfer material P conveyed by the conveyor belt 6 passes, and detect the image forming units PM, PC, PY, and A signal for starting an image forming process in PK is output to an electronic circuit control means, that is, a control unit.

In the above-described color copying machine, a cut sheet is used as the transfer material P as shown in the figure, and the transfer material P is fed out of the paper feed cassette 61 and fed to the paper feed guide 63 of the paper feed device 65. When the image forming unit PM moves inside the image forming units PM and P, the tip of the image forming units PM and P is detected by a detection signal output from the sensor.
C, PY and PK photosensitive drums 1M, 1C, 1Y and 1
K starts rotating. The drive pulley 6a is also driven at the same time, and the transport belt 6 is driven in the direction of the arrow in FIG.
The transfer material P is guided by the paper feed guide 63. When the transfer material P is guided by the paper feed guide 63 and placed on the transport belt 6, the transfer material P receives the corona discharge from the suction charger (not shown) and is reliably attracted onto the transport belt 6. As the transfer belt 6 moves in the direction of the arrow in FIG.
Of the sensors 66M, 66C, 66Y and 66
Each time the light passes through the K detection area, the corresponding photosensitive drum 1
Image forming processes for M, 1C, 1Y and 1K are sequentially started. That is, the magenta image is formed on the photosensitive drum 1M of the first image forming unit PM, the cyan image is formed on the photosensitive drum 1C of the second image forming unit PC, and the third image forming unit PY is formed.
The yellow image is formed on the photosensitive drum 1Y, and the black image is formed on the photosensitive drum 1K of the fourth image forming portion PK. By the movement of the conveyor belt 6, the transfer material P is moved to the first to fourth image forming units PM, PC, P
The transfer material P is conveyed in the direction of the fixing device 8 by sequentially passing under the photosensitive drums 1M, 1C, 1Y, and 1K of Y and PK, and is transferred by the transfer chargers 7M, 7C, 7Y, and 7K of each image forming unit. Above, the visible images of the respective colors formed by the respective image forming apparatuses are sequentially superimposed and transferred, and the color images are synthesized.
After passing through the fourth image forming unit PK, the transfer material P is neutralized by the neutralizer (not shown) to which the AC voltage is applied, and is separated from the transport belt 6. The transfer material P separated from the transport belt 6 is sent to the fixing device 8, and after the developed image transferred in the fixing device 8 is fixed, the transfer material P is discharged from the transfer material discharge port 24 to the paper discharge tray 117, and thus is removed. One copy cycle ends.

The apparatus according to the first embodiment has a mechanism for correcting an image shift (color shift) for each image forming unit as described below. In a state where the transfer material P is not transported, the endless transport belt 6
Is rotated idle, and the test pattern of each color is transferred onto the conveyor belt 6 at a predetermined timing. Generally, a cross pattern is used as the test pattern, and the test patterns of each color are sequentially read by the pattern reading device 12 of FIG. As described with reference to FIG. 3, the reading device 12 includes a reading sensor 12 a of a solid-state imaging device CCD and an imaging lens 12.
c, a test pattern image formed of a visible light cut filter 12d and an illumination lamp 12b and formed of toner that diffusely reflects infrared light is formed on the read sensor 12a through the cut filter 12d and the lens 12c. The test pattern is detected by the output. At this time, the illumination lamp 12b is installed at a certain angle with respect to the transport belt 6 so that the regular reflection light of the illumination lamp 12b with respect to the transport belt 6 does not enter the reading sensor 12a. The reading sensors 12a are arranged in a row in a direction perpendicular to the transport direction so as to be longer than at least the size of the test pattern, and the position in the transport direction (hereinafter referred to as the sub-scanning direction) is a direction perpendicular to the transport direction depending on the time of passage of the read sensor 12a. (Hereinafter referred to as the main scanning direction) is determined based on the range of the output rise of the reading sensor. Then, the positional deviation of the other three colors is corrected based on one color. FIG. 2 shows a block diagram of the correction circuit. The test pattern signal L503 of each color sequentially read by the reading sensor 12a is subjected to processing such as amplification, DC reproduction, A / D conversion, and the like by the CCD driver 95, and as a digital signal L505, the registration controller 9
Sent to 6. The transmitted signal is used by the CPU control to calculate the amount of color misregistration of another color with respect to a certain color reference. As a result, the data signal L at the writing start position is obtained.
509 is sent to the system controller 97, and the optical path and light dew length of each laser beam are adjusted. The data L51
1 is sent to the mirror motor driver 98. The mirror motor driver 98 outputs an appropriate pulse to each motor MM, MC, M
Y, MK, and adjusts the angle of a mirror arranged in the optical path between the laser light source included in the scanning optical devices 3M, 3C, 3Y, 3K and the photosensitive drum according to the rotation amount of these motors. These corrections are supplied to the registration controller 96 by a start signal L510 from the system controller 97 and are executed.

In the present embodiment, the endless transport belt 6
Knead carbon as the material of the material and make the absorption rate of infrared light 80%
As described above, a resin (for example, polyurethane or the like) having a diffuse reflectance of 5% or less was used. The diffuse reflectance of the toner is 4
0% was used. Therefore, each pulley 6a, 6b, 6
The effect of the scratches 6x on the back of the belt caused by the crevices (surface roughness) of d, shavings, dust, or rubbing with various backup members is that the illumination light for the scratches 6x in FIG. 6 and does not pass through the conveyor belt 6, the specularly reflected light
Since it is not taken into D12a, it can be prevented. Further, even when the surface of the conveyor belt 6 has a flaw 6x caused by the rubbing of the transfer material or the photosensitive drum or the belt cleaning means (not shown in FIG. 1), the absorptance hardly changes and the diffuse reflectance is low. , CC of the reading sensor 12a
Since the output of D is stable without being affected by the flaw 6x, erroneous detection can be prevented, and color misregistration correction can be reliably performed. In this embodiment, a toner having a diffuse reflectance of 40% for the infrared light, an absorptivity of the transport belt of 80% or more, and a diffuse reflectance of 5% or less is used. This value is based on the performance of the CCD of the reading sensor 12a. It is determined comprehensively, including

[Embodiment 2] In an apparatus similar to Embodiment 1, an endless transport belt 6 is provided.
Means that the base resin and its absorptivity for infrared light are 80
% Or more, and a resin formed by coating or coating another resin so that the diffuse reflectance is 5% or less. Also in the second embodiment, it is possible to prevent the test pattern from being read due to the damage of the transport belt.

[0024]

According to the first aspect of the present invention, a test pattern for registration correction or correction of image forming means on a conveyor belt is read by a reading device to form a target image. An image forming apparatus having means for recording on a transfer material by using a plurality of image forming means, wherein the image forming apparatus includes a transport belt having an absorptivity to infrared light greater than a transmittance. Since the test pattern is used to detect the position of the test pattern based on the difference in reflectance of the developer on which the test pattern is formed with respect to infrared light, scratches on the back of the conveyor belt can be ignored, and scratches on the surface of the conveyor belt can be eliminated. Since the absorption rate does not decrease, stable test pattern detection is always possible, and it is possible to prevent malfunction of image color shift correction control due to erroneous detection. It made. Therefore, the material of the conveyor belt can be easily selected, and a material that cannot be used conventionally can be used due to a scratch, so that the life can be extended.

In the second invention according to the present invention, the transport belt is made of resin kneaded with carbon in the first invention, so that the light absorption rate can be increased, the reflectance can be reduced, and a developer having a high reflectance can be used. The difference can be increased, and the effect of the first invention can be easily achieved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of Embodiments 1 and 2 of the present invention.

FIG. 2 is a block diagram of color shift correction control according to the first and second embodiments.

FIG. 3 is a longitudinal sectional view of the test pattern reading device according to the first and second embodiments.

FIG. 4 is a diagram showing a CCD output of a reading sensor in FIG. 3;

FIG. 5 is a longitudinal sectional view of a test pattern reading device when a conventional transport belt is used.

FIG. 6 is a diagram showing a CCD output of a reading sensor in FIG. 5;

FIG. 7 is a longitudinal sectional view of the image forming apparatus.

8 is a partially enlarged detailed view of FIG. 7;

FIG. 9 is a perspective view of a conventional example.

10 is a longitudinal sectional view of the transfer material carrying sheet of FIG. 9 according to the moving direction.

[Explanation of symbols]

 1. Photosensitive drum 2. Primary charging device 3. Scanning optical device 4. Developing device 5. Cleaning device 6. Conveyor belt 7. Transfer charger 8. Fixing device 11. Surface potential detector 12. Test pattern reading device 14. Surface voltmeter 16. Density conversion circuit 22. Test pattern 24. Transfer material discharge port 30. Copier body 51 .. Conveyor belt support member 60 .. Transfer material transfer Apparatus 100 Controller

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeshi Fujita 3- 30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yoshihiro Murasawa 3- 30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Masami Izumizaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Koji Amemiya 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Nobunatsu Sasanuma 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-64-48074 (JP, A) JP-A-62-235150 (JP, A) JP-A-57-60347 (JP, A) JP-A-63-298362 (JP, A) JP-A-57-203169 (JP, A) JP-A-62-203169 (JP, A) (JP, U) (58)査the field (Int.Cl. ^7, DB name) G03G 15/01 - 15/01 117

Claims (2)

(57) [Claims] 1. A test pattern provided on a conveyor belt, wherein the test pattern of the conveyor belt is provided.
In an image forming apparatus having reading means for optically reading from the side , and controlling the image forming means based on information obtained by the reading means, the reading means illuminates the test pattern.
Light means for receiving reflected light from the test pattern
An image forming apparatus , comprising: a light receiving unit; wherein the transport belt has an absorptivity for infrared light greater than a transmittance. 2. The image forming apparatus according to claim 1, wherein the transport belt contains carbon.