JP2012128292A - Belt driving device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve productivity by shortening time required from the start of belt driving to the performance of meander correction control.SOLUTION: Based on a distance between plural reference marks on an intermediate transfer belt 8 detected by an HP sensor 205, the position of the intermediate transfer belt 8 in the conveyance direction is identified. Then, based on the identified position of the intermediate transfer belt 8 in the conveyance direction and the positions of ends of the intermediate transfer belt 8 in the width direction detected by an edge sensor 203, the meandering amount of the intermediate transfer belt 8 is calculated.

Description

  The present invention relates to a belt driving device that drives a belt such as an intermediate transfer belt, a fixing belt, and a recording paper conveyance belt, and an image forming apparatus having the belt driving device.

  Conventional image forming apparatuses are provided with various types of belts such as an intermediate transfer belt, a fixing belt, and a recording paper conveyance belt.

  These belts are driven to rotate by being suspended by a plurality of rollers. During the belt rotation process, the belt moves toward one end or the other end in the width direction (hereinafter referred to as meandering). Tend to. Due to the meandering of the belt, the belt may fall off from the roller that is suspending the belt, or the end of the belt may be damaged.

  Therefore, it has an edge sensor that detects the position of the edge (end) in the width direction of the belt, and based on the detection result of the edge sensor, the tilting operation of the steering roller that supports the belt is controlled to correct the meandering of the belt. (For example, refer to Patent Document 1).

  This edge sensor has a contactor that contacts one end of the belt and a displacement sensor that detects a positional variation of the contactor, and continuously detects meandering of the belt. Further, in order to perform highly accurate meandering correction without being affected by the edge shape of the belt, the edge shape data for one round of the belt is stored in advance in the memory as edge profile data. Then, belt meandering correction is performed with high accuracy by canceling belt position fluctuations based on the edge shape of the belt using the edge profile data.

Japanese Patent Laid-Open No. 11-295948

  However, in the invention described in Patent Document 1, the edge profile data is stored in the memory as data for one round of the belt at predetermined intervals with reference to a home position mark (HP mark) provided on the belt.

  For this reason, depending on the positional relationship between the HP mark on the belt and the HP sensor for detecting the HP mark, the belt can be moved up to the time the HP sensor detects the HP mark after driving the belt. It takes time to rotate one round.

  Therefore, there is a problem that it takes a long time from the start of driving the belt until the meandering correction control is performed, the FCOT (First Copy Output Time) becomes long, and the productivity is lowered.

  Therefore, the belt driving device and the image forming apparatus according to the present invention have an object to improve productivity by shortening the time from the start of belt driving until the meander correction control is performed.

  In order to achieve the above object, a belt driving apparatus according to the present invention includes a belt that is supported by a plurality of rollers and that rotates and moves in a predetermined direction, and a first detection unit that detects a plurality of reference marks provided on the belt. A second detecting means for detecting the position of the end of the belt in the width direction perpendicular to the predetermined direction, and by tilting the axis of any one of the plurality of rollers, Control means for correcting meandering, wherein the plurality of reference marks are arranged on the belt so that the intervals between the reference marks are different, and the control means is detected by the first detection means. The position of the belt in the predetermined direction is specified based on the interval between the plurality of reference marks, and the position of the specified belt in the predetermined direction is detected by the second detection unit. Based on the position of the end portion in the width direction of the belt, and calculating the meandering amount of the belt.

  An image forming apparatus according to the present invention includes the belt driving device described above and an image forming unit that forms an image on a recording sheet, and the belt is an intermediate transfer belt on which a toner image is transferred from a photoreceptor. A fixing belt for fixing the toner image on the recording paper, or a recording paper conveyance belt for conveying the recording paper.

  According to the present invention, it is possible to shorten the time from the start of driving the belt until the meandering correction control is performed, and it is possible to improve productivity.

1 is a cross-sectional view illustrating an overall configuration of an image forming apparatus including a belt driving device. It is a figure which shows schematic structure for demonstrating the meandering correction | amendment control of an intermediate transfer belt. FIG. 6 is a diagram for explaining the principle of meandering correction of an intermediate transfer belt. It is a figure which shows the specific structure of an edge sensor. FIG. 3 is a plan development view of an intermediate transfer belt. 2 is a control block diagram of the image forming apparatus. FIG. It is a figure which shows the amount of meandering of edge profile data and an intermediate transfer belt. It is a figure which shows the address where edge profile data is stored. It is a flowchart which shows meandering correction control.

FIG. 1 is a cross-sectional view illustrating an overall configuration of an image forming apparatus including a belt driving device.
The image forming apparatus 1 is an electrophotographic full-color printer that forms an image on recording paper. The image forming apparatus 1 includes four color photoconductors 2a to 2d, chargers 3a to 3d, cleaners 4a to 4d, laser scanning units 5a to 5d, transfer blades 6a to 6d, developing devices 7a to 7d, and an intermediate transfer belt 8. And a cleaner 12 are provided. Further, the image forming apparatus 1 is provided with a steering roller 10 that supports the intermediate transfer belt 8 and a belt driving roller 11 that rotates and moves the intermediate transfer belt 8 in a predetermined direction.

  A plurality of recording sheets S set on the manual feed tray 13 are separated into a single sheet by a pickup roller 14 and a separation roller 15 and fed. On the other hand, a plurality of recording sheets S stored in the sheet feeding cassette 17 are separated and fed by a pickup roller 18 and a separation roller 19 and then conveyed by a vertical path roller 20.

  The fed recording sheet S is conveyed to the secondary transfer roller 22 while the registration roller 16 sets the registration timing. Here, the rollers 14, 15, 16, 18, 19, and 20 for transporting the recording paper S are each driven by an independent stepping motor in order to realize a high-speed and stable transport operation.

  On the other hand, the chargers 3a to 3d uniformly charge the surfaces of the photoreceptors 2a to 2d. Each of the laser scanning units 5a to 5d using the semiconductor laser as a light source irradiates the photosensitive members 2a to 2d of the respective colors with lasers, thereby forming electrostatic latent images on the surfaces of the respective photosensitive members 2a to 2d. . The developing devices 7a to 7d develop the electrostatic latent image as a toner image.

  Next, the transfer blades 6 a to 6 d transfer the color toner images developed on the photoreceptors 2 a to 2 d to the intermediate transfer belt 8. The toner image on the intermediate transfer belt 8 is transferred to the recording paper at the nip portion between the rotating roller 21 and the secondary transfer roller 22. Then, heat is applied to the toner image transferred onto the recording paper by the fixing device 23 having a heating roller, and the toner image is fixed onto the recording paper.

  In double-sided printing, the recording paper S that has passed through the fixing unit 23 is guided in the direction of the double-sided reversing path 27 and then conveyed in the reverse direction so that the front and back are reversed and conveyed to the double-sided path 28. The recording paper S that has passed through the double-sided path 28 is conveyed again by the vertical path roller 20, forms an image on the second side as with the first side, and is discharged to the paper discharge tray 25 by the paper discharge roller 24.

FIG. 2 is a diagram showing a schematic configuration for explaining the meandering correction control of the intermediate transfer belt 8.
The HP sensor 205 as a first detection unit is a sensor for detecting a plurality of reference marks (described later in FIG. 5) provided at the end of the intermediate transfer belt 8. The steering roller 10 is a roller for correcting movement variation (meandering) in the width direction of the intermediate transfer belt 8. On the downstream side of the steering roller 10 in the belt conveyance direction, an edge sensor 203 as a second detection unit is disposed. The edge sensor 203 detects the amount of movement of the contact 202 disposed so as to contact the end (edge) of the intermediate transfer belt 8 and generates an output signal corresponding to the meandering of the intermediate transfer belt 8.

  A position variation in the width direction of the intermediate transfer belt 8 can be detected according to the detection result of the edge sensor 203, and the tilting operation of the steering roller 10 is controlled based on the position variation. Thereby, the meandering of the intermediate transfer belt 8 can be corrected.

FIG. 3 is a diagram for explaining the principle of meandering correction of the intermediate transfer belt.
From the left of this figure, a front view of the eccentric cam 208, a side view of the eccentric cam 208 and the steering roller 10, and a front view of the steering roller 10 are shown. The front view of the steering roller 10 is a view of the steering roller 10 shown in the side view from the right side.

  As shown in FIG. 3A, in the state where the eccentric cam 208 stops at a predetermined angle and the steering roller 10 is held substantially horizontal (tilt is almost zero) corresponding to the stop angle, the basic operation is basically performed. Does not have the force to correct the position of the intermediate transfer belt.

  3B, when the eccentric cam 208 is rotated by driving the steering motor 209, the swing arm 206 swings in the θ1 direction according to the amount of eccentricity of the eccentric cam 208. Thereby, since one end of the steering roller 10 is lifted by the swing arm 206, the steering roller 10 is inclined according to the lift amount. At this time, the intermediate transfer belt 8 wound around the steering roller 10 moves to the roller end side lifted by the swing arm 206.

  On the other hand, as shown in FIG. 3C, when the eccentric cam 208 is rotated by driving the steering motor 209, the swing arm 206 swings in the θ2 direction according to the amount of eccentricity of the eccentric cam 208. . Thereby, since one end of the steering roller 10 is pushed down by the swing arm 206, the steering roller 10 is inclined according to the amount of the push-down. At this time, the intermediate transfer belt 8 wound around the steering roller 10 moves to the side opposite to the roller end pushed down by the swing arm 206.

  Therefore, the position variation in the width direction of the intermediate transfer belt 8 is continuously detected by the edge sensor 203, and the tilting operation of the steering roller 10 is controlled based on the detection result, whereby the meandering of the intermediate transfer belt 8 is performed. Can be corrected.

FIG. 4 is a diagram illustrating a specific configuration of the edge sensor.
As shown in this figure, one end of the contactor 202 is held in pressure contact with the end of the intermediate transfer belt 8 by receiving a pulling force from the spring 401. The pressing force of the contactor 202 by the spring 401 is set to an appropriate magnitude so as not to deform the intermediate transfer belt 8.

  Further, the intermediate portion of the contactor 202 is rotatably supported by the support shaft 402. The displacement sensor 403 is disposed to face the other end side of the contactor 202. The displacement sensor 403 is an optical distance measuring sensor having a light emitting element and a light receiving element. The displacement sensor 403 emits light from the light emitting element toward the contactor 202 and receives light reflected from the contactor 202 by the light receiving element. And the displacement sensor 403 detects the displacement of the contactor 202 by outputting a signal corresponding to the light receiving position in the light receiving element.

  The edge sensor 203 replaces the movement amount in the width direction orthogonal to the traveling direction of the intermediate transfer belt 8 with the movement of the contactor 202 that presses against the end of the intermediate transfer belt 8. At this time, since the output level of the displacement sensor 403 varies according to the displacement of the contactor 202, the position variation of the end of the intermediate transfer belt 8 can be continuously detected based on the displacement sensor 403 output.

FIG. 5 is a developed plan view of the intermediate transfer belt.
A plurality of reference marks are provided on the intermediate transfer belt 8, and the position of the intermediate transfer belt 8 with respect to the home position HP can be detected by a combination of reference marks detected by the HP sensor 205. In this embodiment, the peripheral length of the intermediate transfer belt 8 is 990 mm, and 18 reference marks having a width of 5 mm are provided on the intermediate transfer belt 8.

  The reference mark a is arranged so that the tip end portion is aligned with the boundary lines (HP and A to H) of the regions R1 to R9 that are divided into nine equal parts on the entire circumference of the intermediate transfer belt 8. In the region R1, the reference mark b is arranged with an interval of 10 mm from the reference mark a. In the region R2, the reference mark b is arranged with an interval of 20 mm from the reference mark a. Hereinafter, in the range of R3 to R9, the reference mark b is arranged by increasing the interval by 10 mm according to the same rule.

  During the period when the HP sensor 205 is detecting the reference mark, the output of the HP sensor 205 is at the Hi level. Conversely, during a period when the HP sensor 205 does not detect the reference mark, the output of the HP sensor 205 is at a low level.

  In this embodiment, the speed of the intermediate transfer belt 8 is 200 mm / s. In this case, the low level period is 50 mS, 450 mS, 100 mS, 400 mS, 150 mS, 350 mS, 200 mS, 300 mS, 250 mS, 250 mS, 300 mS, 200 mS, 350 mS, 150 mS, 400 mS, 100 mS, 450 mS, 50 mS, 50 mS, 450 mS,.・ It will be detected in order.

  For example, when the Low level period is detected in the order of 50 mS and 450 mS, the HP sensor 205 is positioned at the boundary A between the region R1 and the region R2. This boundary A is a position 110 mm away from the home position HP of the intermediate transfer belt 8. Similarly, when the Low level period is detected in the order of 100 mS and 400 mS, the HP sensor 205 is positioned at the boundary B. The detection is similarly performed for the boundary C and below.

FIG. 6 is a control block diagram of the image forming apparatus.
The control unit 501 includes a CPU 502, a ROM 503, and a RAM 504. The CPU 502 is a control circuit that controls the entire image forming apparatus 1. The ROM 503 stores a control program for controlling various processes executed by the image forming apparatus 1.

  A RAM 504 is a system work memory for the CPU 502 to operate, and also functions as an image memory for temporarily storing image data. A hard disk drive (HDD) 505 stores data such as system software and image data.

  The belt drive motor 210 is a motor for driving the belt drive roller 11 that rotates the intermediate transfer belt 8. A display unit 506 is a touch panel display, and has a function of receiving an operation input from a user and a function of displaying the state of the image forming apparatus 1.

  In the HDD 505, edge profile data P inherent to the intermediate transfer belt 8 is stored in advance with reference to the home position of the intermediate transfer belt 8. The edge profile data P is data indicating the shape data of the end of the intermediate transfer belt 8 on the side where the contact 202 abuts. When the edge profile data P is used, it is read from the HDD 505 and stored in the RAM 504.

  The CPU 502 specifies the position of the intermediate transfer belt 8 in the conveyance direction of the intermediate transfer belt 8 based on the signal output from the HP sensor 205. Then, the CPU 502 reads edge profile data P corresponding to the specified position of the intermediate transfer belt 8 from the RAM 504. The reading of the edge profile data P is sequentially performed at a predetermined interval.

  Further, the CPU 502 takes in edge data E corresponding to the edge profile data P read from the RAM 504 from the edge sensor 203 during the rotational movement of the intermediate transfer belt 8. The CPU 502 calculates a position change amount (displacement) corresponding to the meandering amount of the intermediate transfer belt 8 from the sequentially read edge profile data P and the captured edge data E.

  Further, the CPU 502 outputs a steering control signal including a driving direction and a driving amount to the steering motor 209 so as to reduce meandering according to the calculated displacement of the intermediate transfer belt 8, thereby driving the steering motor 209. As the steering motor 209 and the belt drive motor 210, a stepping motor capable of controlling the rotation angle and rotation speed with high accuracy is used.

FIG. 7 is a diagram showing edge profile data and the meandering amount of the intermediate transfer belt.
FIG. 7A shows the edge profile data P. FIG. The end (edge) of the intermediate transfer belt 8 is not completely straight but slightly distorted. Therefore, the shape of the end of the intermediate transfer belt 8 is measured at the time of shipment from the factory, and is stored in the HDD 505 as edge profile data P.

  FIG. 7B shows the meandering amount D and edge data E of the intermediate transfer belt 8. The edge data E, which is the output of the edge sensor 203, is data detected by adding the amount of distortion at the end of the intermediate transfer belt 8 to the meandering amount of the intermediate transfer belt 8. Therefore, the meandering amount D of the intermediate transfer belt 8 is calculated by subtracting the edge profile data P from the edge data E by the CPU 502. Based on the meandering amount D of the intermediate transfer belt 8 obtained here, the CPU 502 outputs a steering control signal so as to cancel the meandering.

FIG. 8 is a diagram showing an address of the RAM in which the edge profile data is stored.
The edge profile data P is read from the HDD 505, stored in the RAM 504, and used. The edge profile data P is stored in the RAM 504 with addresses (hexadecimal) assigned in order from the position of the home position HP (see FIG. 5) of the intermediate transfer belt 8.

  The profile data at the home position HP of the intermediate transfer belt 8 is stored at address 00001, the profile data at position A is stored at address 00A01, and the profile data at position B is stored at address 00B01. Similarly, C to H are stored in addresses 00C01, 00D01,..., 00F01, 01001, and 01101, respectively.

  For each of the regions R1 to R9 (see FIG. 5) divided into nine equal parts, the sampling period is 10 ms and the number of samplings is 55 times. The number of samplings for one turn of the intermediate transfer belt 8 is 55 × 9 = 495 times.

  FIG. 9 is a flowchart showing meandering correction control.

  A program for executing this flowchart is stored in the ROM 503 and is executed by being read by the CPU 502.

  First, the CPU 502 determines whether or not an image formation request has been made by the user pressing the start key on the display unit 506 (S901). If there is an image formation request, the CPU 502 drives the belt drive motor 210 to start the rotation of the intermediate transfer belt 8 (S902).

  Next, as described with reference to FIG. 5, the CPU 502 waits until the position of the intermediate transfer belt 8 is specified based on the period when the output of the HP sensor 205 is at the low level (S903).

  When the position of the intermediate transfer belt 8 is specified, the CPU 502 calculates the address X on the RAM 504 of the edge profile data P corresponding to the specified position of the intermediate transfer belt 8 (S904). For example, if the intermediate transfer belt 8 is at the home position HP, the address X is 00001, and if it is at the position A in FIG. 5, the address X is 00A01, and BB to H are similarly 00B01, 00C01,. 01101.

  Next, the CPU 502 acquires the edge profile data P from the address X on the RAM 504 (S905), and acquires the edge data E that is the output value of the edge sensor 203 (S906). Thereafter, the CPU 502 calculates a meandering amount D based on the edge profile data P and the edge data E as described in the description of FIG. 7 (S907). Based on the calculated meandering amount D, the CPU 502 transmits a steering control signal for controlling the steering roller 10 to the steering motor 209 (S908).

  Next, the CPU 502 determines whether the address X = 0 ** 37 (* is arbitrary) (S909). If the last two digits are 37, since all sampling has been completed in the current region among the regions R1 to R9, step S903 is performed to detect the position of the intermediate transfer belt 8 based on the next reference mark. Return to.

  If the last two digits are not 37, the CPU 502 calculates whether the meandering amount D is calculated in step S907, and then determines whether or not 10 ms that is the sampling period has elapsed (S910). If 10 ms has elapsed, the CPU 502 adds 1 to the address X (S911), and returns to step S905 described above.

  If 10 ms has not elapsed in step S911, the CPU 502 determines whether or not to end the image forming operation (S912). Here, when the image formation of the last page is completed, the CPU 502 determines to end the image forming operation.

  If it is determined in step S912 that the image forming operation is not finished, the process returns to step S910 described above. If it is determined that the image forming operation is to be ended, the CPU 502 stops the rotation of the intermediate transfer belt 8 by stopping the driving of the belt driving motor 210 (S913), and this flow is ended.

  As described above, according to the present embodiment, it is possible to shorten the time from the start of belt driving until the meandering correction control is performed, thereby improving productivity.

  In the above description, the intermediate transfer belt is taken as an example of the belt. However, the belt is provided in an image forming apparatus such as a fixing belt for fixing a toner image on the recording paper or a recording paper conveying belt for conveying the recording paper. The same control may be performed on the belt.

  Further, the present invention is not limited to the configuration of the present embodiment with respect to the number of reference marks, the mark shape, and the mark interval. If the position of the intermediate transfer belt 8 is calculated and the meandering correction control using the edge profile data P is possible, the number of marks, the shape, the interval, etc. are not limited.

1 Image forming device 8 Intermediate transfer belt (corresponding to belt)
10 Steering roller 11 Belt drive roller 203 Edge sensor (corresponding to second detection means)
205 HP sensor (corresponding to the first detection means)
209 Steering motor 210 Belt drive motor 502 CPU (corresponding to control means)
504 RAM (corresponding to storage means)

Claims (4)

A belt supported by a plurality of rollers and rotating in a predetermined direction;
First detection means for detecting a plurality of reference marks provided on the belt;
Second detection means for detecting the position of the end of the belt in the width direction perpendicular to the predetermined direction;
Control means for correcting meandering of the belt by inclining the axis of any one of the plurality of rollers,
The plurality of reference marks are arranged on the belt such that intervals between the reference marks are different from each other,
The control means specifies the position of the belt in the predetermined direction based on the interval between the plurality of reference marks detected by the first detection means, and the position of the specified belt in the predetermined direction; A belt driving device that calculates a meandering amount of the belt based on a position of an end of the belt in the width direction detected by a second detection unit. Storage means for storing edge profile data indicating shape data for one round of the end of the belt;
The control means reads the edge profile data corresponding to the specified position of the belt in the predetermined direction from the storage means, and the read edge profile data and the second detection during the rotational movement of the belt. 2. The belt driving apparatus according to claim 1, wherein the position of the belt in the width direction is controlled based on edge data obtained from the output of the means.   The control means calculates the meandering amount of the belt by subtracting the edge profile data from the edge data, and controls the position of the belt in the width direction according to the computed meandering amount. The belt driving device according to claim 2. A belt drive device according to any one of claims 1 to 3,
Image forming means for forming an image on a recording paper,
The belt is an intermediate transfer belt to which a toner image is transferred from a photosensitive member, a fixing belt for fixing a toner image on a recording paper, or a recording paper transport belt for transporting a recording paper. .

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