JP3288072B2 - 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 utilizing an electrophotographic technique, such as a copying machine and a laser beam printer.

[0002]

2. Description of the Related Art FIGS. 1 and 2 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. 2 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. 2, 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.

As described above with reference to FIG. 1, the transport belt for transporting the transfer material is wound around a pulley such as a drive pulley and is transported linearly and parallel along each photosensitive drum. The transport state of the transport belt fluctuates due to mechanical vibrations due to the tension and load of the
Since a situation occurs in which the conveyor belt is conveyed while moving in one direction, the conveyance state of the conveyor belt is shifted, for example, the end of the conveyor belt is monitored by a sensor, and a load is applied to the conveyor belt. The shift of the conveyor belt is controlled so as to shift. Therefore, the conveyor belt is controlled to swing in the left-right direction and is traveling.

[0007]

In the conventional belt swing control, since a load is simply applied to the transport belt in a direction in which it is desired to return, for example, there is a problem in a mechanism, for example, the transport belt is supported. If the degree of misalignment of the pulleys in one direction is different from the degree of misalignment in one direction and the degree of misalignment when returning the bias of the conveyor belt by applying a load in the opposite direction is different, it is easy to move in only one direction,
Also, because the speed of the shift of the conveyor belt cannot be controlled,
For example, it is delayed to return in the reverse direction, causing the edge of the conveyor belt to slide and damage other objects, and conversely, the swing speed is too fast, which adversely affects the image being transferred. There was a problem.

[0008]

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

According to a first aspect of the present invention, there is provided an image carrier, a conveyor belt for carrying and transferring a transfer material onto which an image on the image carrier is transferred, and detecting a deviation in the width direction of the conveyor belt. Displacement detection means, and displacement correction means for correcting the displacement by moving the position of the conveyor belt in the width direction opposite to the displacement side detected by the displacement detection means, Wherein the control value for driving the deviation correcting means differs depending on the direction of movement in the width direction.

According to a second aspect of the present invention, there is provided an image carrier, a conveyor belt for carrying and transferring a transfer material onto which an image on the image carrier is transferred, and detecting a shift in the width direction of the conveyor belt. Displacement detection means, and a predetermined position in the width direction opposite to the displacement side detected by the displacement detection means,
A shift correcting means for correcting the shift by moving the position of the transfer belt, wherein the transfer belt is positioned at the detected shift position.
A control value for driving the shift correcting means from the time when it reaches the predetermined position to the predetermined position is intermittently given to the shift correcting means every predetermined time, and the control value for each predetermined time elapses. And an image forming apparatus that changes with time.

[0011]

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

FIG. 3 is a schematic view of an embodiment of the image forming apparatus according to the present invention. An image is written on the photosensitive drums 1M, 1C, 1Y, and 1K by the scanning optical device 3 in accordance with image information. The images written with the rotations of the arrows 1C, 1Y, and 1K in the directions of the arrows are the respective developing devices 4M,
Developed by 4C, 4Y, 4K. On the other hand, the transfer material is conveyed from the paper feed cassette 61 onto the conveyance belt 6 and the images developed and formed on the respective photosensitive drums are transferred onto the transfer material by the transfer chargers 7M, 7C, 7Y and 7K in order from the right.
After being superposed, the image is fixed by the fixing device 8 and is discharged. While the formation of a multiplex image is performed by the above-described process, the scanning optical device 3 uses the scanning optical device 3 to precisely overlap the images formed by the photosensitive drums 1M, 1C, 1Y, and 1K. Test patterns (for example, # marks) for position detection are written and developed at two locations on the back and front on 1C, 1Y, and 1K, and are transferred onto the transport belt 6, and the transport belt 6 receives the photosensitive drums 1M, 1C, 1Y, 1
Test mark reading device 1 for # mark corresponding to K
When the scanning optical system is moved to the position 2, the # mark is read to detect a writing displacement, an inclination, a magnification, and the like in the image forming unit corresponding to each of the photosensitive drums 1M, 1C, 1Y, and 1K. The writing timing of the device 3 and the inclination of the mirror are corrected.

Embodiments 1 and 2 address the above problem.
An object of the present invention is to solve the problem of controlling the position of the conveyor belt from only one side of the conveyor belt.

Embodiment 1 FIG. 4 is a longitudinal sectional view illustrating the configuration of an image forming apparatus according to Embodiment 1 of the present invention. A reader unit 101 includes an image sensor for reading a color image and a series of images. The reading sequence is controlled by the reader controller RCON.

The printer unit 102 includes a plurality of photosensitive drums (image carriers) 1M, 1C, 1Y, and 1K arranged side by side, and forms a magenta image, a cyan image, and a yellow image formed on each of the photosensitive drums 1M, 1C, 1Y, and 1K. The black image is sequentially transferred onto a transfer material of a recording medium sequentially conveyed to the conveyance belt 6 so that a plurality of color images (a full-color image in this embodiment) can be formed.

The scanning optical device 3 is a scanner which scans the photosensitive drums 1M, 1C, 1Y, 1K with laser beams L1 to L4 (see FIG. 5) modulated based on color image signals corresponding to respective colors. A laser, a scanning mirror, a folding mirror (movably configured), and the like are provided.

The driving of the printer unit 102 is controlled by a printer controller PCON, and includes processing means for executing control of a transfer material conveying device and image forming means.

FIG. 5 is an enlarged sectional view of a main portion around the conveyor belt 6 shown in FIG. 4, and the same components as those in FIG. 4 are denoted by the same reference numerals.

In the figure, a drive motor 9M for driving the photosensitive drum 1M and a drive motor 9 for driving the photosensitive drum 1C
C, a drive motor 9Y for driving the photosensitive drum 1Y and a drive motor 9K for driving the photosensitive drum 1K. The illumination lamps 12b-1 and 12b-2 illuminate the registration correction test pattern transferred on the transport belt 6 in a direction orthogonal to the transport direction, for example. The imaging lens 12c forms the reflected light of the test pattern on the transport belt 6 into an image on the reading sensor 12a via the mirror 12e.

The driving motor 10 transmits a rotational force to the driving pulley 6a, and conveys the conveying belt 6 around at a predetermined speed.

The transport belt 6 includes a driving pulley 6a, a driven pulley 6b, a tension pulley 6d, and a belt swing pulley 6e.
, The driving pulley 6a, the driven pulley 6b
The portion of the conveyor belt 6 stretched between the photosensitive drums 1
M, 1C, 1Y. The portion in contact with 1K is the transfer portion. The belt oscillating pulley 6e is a movable bearing 72 similar to a bearing 71 that allows the shaft 6e-1 of the pulley 6e to tilt such as a spherical ball bearing whose shaft 6e-1 is fixed as shown in FIG.
It is supported rotatably. The movable bearing 72 is accommodated in a bearing box 73 guided by a guide 74 fixed in parallel with the moving direction of the conveyor belt 6. Guide 7 in bearing box 73
A feed screw 75 parallel to 4 is screwed. The belt oscillation correction motor 76 such as a pulse motor is
5. When the motor 76 for positive rotation of the belt 9 is driven, the feed screw 75 rotates and the bearing box 73
Is guided by the guide 74 and moves parallel to the transport direction of the transport belt 6. For example, when the movable bearing 72 on the near side in FIG. 6 is moved to the right, the transport belt 6 is shifted toward the far side by the tension due to the axial inclination. If the belt swing pulley 6e is moved in the opposite direction to the above, the transport belt 6 comes closer to the front due to the tension due to the axial inclination. And, the greater the inclination of the axis of the oscillating pulley 6e, the faster the speed of the transport belt 6 in one direction.

FIG. 7 shows a flowchart of the belt swing control method according to the present invention. A left end detection sensor (not shown) of the conveyance belt 6 (here, the left end detection sensor of the conveyance belt 6 is a sensor that detects a belt end on the left side of the conveyance belt 6 when viewed toward the downstream side in the traveling direction of the conveyance belt 6. 6 Print controller PCON not shown left end
It is checked whether or not is detected (step 1). If the print controller PCON determines that it has detected,
The belt swing correction motor 76 is rotated so that the front side of the belt swing pulley 6e in FIG. 6 moves rightward by a specified value so that the conveyor belt 6 moves rightward (step 2). When the print controller PCON does not detect the left end of the conveying belt 6, a belt right end detecting sensor (not shown) is a sensor that detects the right end of the conveying belt 6 toward the downstream side in the belt traveling direction. ) To check whether the right end of the conveyor belt 6 has been detected (step 3). If the print controller PCON determines that the right end of the conveyor belt 6 has been detected, the belt oscillation correction motor 76 is moved to the left in FIG. 6 so that the conveyor belt 6 moves to the left. (Step 4).

As described above, the print controller PCON gives independent control values to the rocking correction motor for the rocking to the left and right, thereby coping with a case where the motor is easily shifted in one direction mechanically. Control becomes possible.

Embodiment 2 In Embodiment 1, with respect to rightward swing and leftward swing,
Although the swing amount was controlled by giving another control value, the second embodiment shows that the swing speed can be controlled by changing this control value with time.

FIG. 8 shows a flowchart of the second embodiment.
It is checked whether the print controller PCON (not shown) detects the left end of the conveyor belt 6 by the belt left end detection sensor (step 1). Print controller P
If the CON determines that the left end of the conveyor belt 6 has been detected, the belt oscillation correction motor 76 is moved to the belt oscillation pulley 6 in FIG.
The belt swing correction motor 76 is rotated by a predetermined amount so as to move the front side of e to the right by a specified value (step 2). It is checked whether a predetermined time has elapsed since the rotation of the belt oscillation correcting motor 76 (step 3). If a certain period of time has elapsed since the rotation of the belt oscillation correcting motor 76, the flow returns to (Step 2), and the belt oscillation correcting motor 76 is rotated by a predetermined value in the same direction as the above by a predetermined amount. If the predetermined time has not elapsed, it is checked whether the belt left end detection sensor detects the left end of the conveyor belt 6 (step 4). When the left end of the belt is continuously detected, the process returns to (Step 3). If the belt left end detection sensor does not detect the left end of the belt, the control is stopped because the conveyor belt 6 is no longer located at the left end.

The conveyor belt 6 is detected by the belt left end detection sensor.
If it is determined that the print controller PCON (not shown) has not detected the left end of the transfer belt 6, it is checked whether or not the print controller PCON (not shown) has detected the right end of the conveyor belt 6 by the belt right end detection sensor (step 5). If the print controller PCON determines that the right end of the conveyor belt 6 has been detected, the belt swing correction motor 76 is moved in the leftward direction of the belt swing pulley 6e in FIG. 6 so that the conveyor belt 6 moves to the left. Belt swing correction motor 76 so that
It is checked whether a predetermined time has elapsed since the rotation of the (Step 7). If a certain period of time has elapsed since the rotation of the belt oscillation correction motor 76, the flow returns to (Step 6), and the belt oscillation correction motor 76 is rotated in the same direction by a fixed amount by the regulation value. If the predetermined time has not elapsed, it is checked whether the belt right end detection sensor detects the right end of the conveyor belt 6 (step 8). If the detection is continued, the process returns to (Step 7). If the belt right end detection sensor has not detected the right end of the belt, the control is stopped because the conveyor belt 6 is no longer located at the right end (step 8).

The specified value for turning the motor every fixed time gives an optimum value depending on the state and time of the belt end sensor.

[0028]

As described above, according to the first aspect of the present invention, the amount of movement of the conveyor belt in the width direction is made different between the left and right sides, so that the degree of the deviation of the belt between the left and right sides due to, for example, an alignment error. Even in different apparatuses, a control value according to the degree of left and right deviation can be set, and appropriate deviation control can be performed.

According to the second aspect of the present invention, when the transport belt is moved a plurality of times in small increments, by changing the control value according to the elapsed time, finer control suited to the device characteristics can be achieved. Can do it.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of an image forming apparatus.

FIG. 2 is a partially enlarged detailed view of FIG. 1;

FIG. 3 is a schematic longitudinal sectional view of the image forming apparatus according to the embodiment of the present invention.

FIG. 4 is a longitudinal sectional view illustrating a configuration of an image forming apparatus according to the first exemplary embodiment of the present invention.

FIG. 5 is an enlarged cross-sectional view of a main part around the conveyance belt shown in FIG.

FIG. 6 is a horizontal sectional view of the conveyor belt swinging device.

FIG. 7 is a flowchart illustrating a transport belt swing control algorithm according to the first embodiment of the present invention.

FIG. 8 is a flowchart illustrating a conveyance belt swing control algorithm according to a second embodiment of the present invention.

[Explanation of symbols]

 1. photosensitive drum 2. primary charging device 3. scanning optical device 4. developing device 5. cleaning device 6. transport belt 7. transfer charging device 8. fixing device 10. driving motor 11.・ Surface potential detector 12 ・ ・ Test pattern reader 14 ・ ・ Surface potential detector 16 ・ ・ Density conversion circuit 22 ・ ・ Test pattern 60 ・ ・ Transfer material transfer device 76 ・ ・ Motor for belt swing correction 100 ・ ・ Controller 101 ··· Leader section 102 ··· Printer section

Continued 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 Canon Inc. (72) Inventor Masami Izumizaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Koji Amemiya 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Nobunatsu Sasanuma 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-3-177221 (JP, A) JP-A-4-63389 (JP, A) JP-A Sho 57-24955 (JP, A) JP-A-3-288167 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/01-15/01 117 G03G 21/00 370- 502 G03G 21/14

Claims (2)

(57) [Claims] An image carrier, a conveyor belt for carrying and transferring a transfer material onto which an image on the image carrier is transferred, a shift detecting unit for detecting a shift in the width direction of the conveyor belt, In the image forming apparatus having a shift correction unit that corrects the shift by moving the position of the transport belt toward the width direction opposite to the shift side detected by the shift detection unit, An image forming apparatus according to claim 1, wherein a control value for driving said deviation correcting means differs in the direction of movement in said width direction. 2. An image carrier, a conveyor belt for carrying and transferring a transfer material onto which an image on the image carrier is transferred, a shift detecting unit for detecting a shift in the width direction of the conveyor belt, Image forming apparatus comprising: a shift correcting unit that corrects a shift by moving a position of the transport belt to a predetermined position in a width direction opposite to the shift side detected by the shift detecting unit. In the apparatus, the transport belt is moved forward from the detected one-side position.
Until the predetermined position is reached, a control value for driving the shift correction means is intermittently given to the shift correction means every predetermined time, and the control value for each shift of the predetermined time is: An image forming apparatus characterized by changing over time.