JP2012133217A - Belt driving device and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve productivity by shortening time required from the start of driving of a belt to execution of a meander correction control, and to achieve cost reduction.SOLUTION: Edge profile data P showing shape data of one round of the end part of an intermediate transfer belt 8 is stored in a RAM 504 in association with the count value of a signal output from an encoder 61 attached to a drive roller 11. Edge profile data P corresponding to the count value of the signal output from the encoder 61 is read out from the RAM 504, and the meandering amount of the intermediate transfer belt 8 is calculated based on the readout edge profile data P and edge data E obtained by output of an edge sensor 203 during rotational movement of the intermediate transfer belt 8.

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. Further, since an HP sensor for detecting the HP mark on the belt is separately required, there is a problem that the cost is increased.

  Therefore, the belt driving device and the image forming apparatus according to the present invention improve the productivity by reducing the time from the start of the belt driving until the meander correction control is performed, and also realize the cost reduction. With the goal.

  In order to achieve the above object, a belt driving device according to the present invention detects a position of a belt supported by a plurality of rollers and rotated in a predetermined direction, and an end portion of the belt in a width direction orthogonal to the predetermined direction. Detecting means, an output means for outputting a signal in synchronization with the rotation of any one of the plurality of rollers, and an end of the belt in association with a count value of a signal output from the output means. Storage means for storing edge profile data indicating shape data for one round of the part, control means for correcting meandering of the belt by inclining the axis of any one of the plurality of rollers, The control means reads the edge profile data corresponding to the count value of the signal output from the output means from the storage means and reads A serial edge profile data, based on the obtained edge data by an output of said detecting means during rotational movement of said 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 improve the productivity by reducing the time from the start of driving the belt until the meander correction control is performed, and to realize a reduction in cost.

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. 6 is a diagram illustrating a relationship between an encoder output and an intermediate transfer belt conveyance amount. 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 flowchart which shows edge profile data acquisition control. FIG. 10 is a diagram illustrating a method for determining whether or not the total number of pulses for one rotation of the intermediate transfer belt has been reached. It is a figure which shows the address where edge profile data is stored. 6 is a flowchart showing meandering correction control of an intermediate transfer belt.

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 steering roller 10 is a roller for correcting movement variation (meandering) in the width direction of the intermediate transfer belt 8. An edge sensor 203 is disposed downstream of the steering roller 10 in the belt conveyance direction. 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.

  The drive roller 11 is provided with an encoder 61. The encoder 61 includes a disc 55 provided with slits at equal intervals and a slit sensor 56 that detects the slits. The disk 55 attached to the shaft of the drive roller 11 rotates with the rotation of the drive roller 11 and is controlled so that the drive roller 11 is rotationally driven at a constant speed according to the output of the slit sensor 56 at this time.

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 as viewed from the A direction.

  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 diagram illustrating a relationship between the output of the encoder and the conveyance amount of the intermediate transfer belt.
In this embodiment, the peripheral length of the intermediate transfer belt 8 is 960 mm, and the peripheral length of the driving roller 11 is 120 mm (diameter 38.2 mm). For this reason, the intermediate transfer belt 8 is rotated once by the drive roller 11 rotating eight times.

  The drive roller 11 is provided with an encoder 61, and the encoder 61 outputs 240 pulses by one rotation of the drive roller 11. From the above, the intermediate transfer belt 8 moves 0.5 mm per pulse, and the intermediate transfer belt 8 makes one round with 1920 pulses.

  However, since the diameters of the drive roller 11 and the intermediate transfer belt 8 change due to manufacturing variations and thermal expansion, if one cycle of the intermediate transfer belt 8 does not necessarily have 1920 pulses, control is performed with 1920 pulses. The error increases. The number of pulses per revolution of the intermediate transfer belt 8 varies depending on the environment and the machine. Therefore, it is necessary to measure the number of pulses per revolution of the intermediate transfer belt 8 and perform control using the measured value.

  Measurement of the number of pulses for one rotation of the intermediate transfer belt 8 is performed as part of edge profile data acquisition control (FIG. 8) described later. Further, it is assumed that the number of pulses of the encoder 61 per rotation of the intermediate transfer belt 8 is not a minimum value of 1920 pulses or less.

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 for one round of belt inherent to the intermediate transfer belt 8 is stored in advance with reference to the home position HP of the intermediate transfer belt 8. Note that the home position HP of the present embodiment is not a mark provided on the intermediate transfer belt 8 as in the prior art, but is a virtually determined position, and the edge profile data acquisition control of FIG. It will be described later.

  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 pulse output from the encoder 61. 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 factory shipment or the like, 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 flowchart showing edge profile data acquisition control.
A program for executing this flowchart is stored in the ROM 503 and is executed by being read by the CPU 502. This control is performed at the time of factory shipment or when the intermediate transfer belt 8 is replaced. Further, it may be performed when a predetermined temperature change or more has occurred since the last acquisition of the edge profile data P, or when the intermediate transfer belt 8 has been conveyed for a predetermined time or more.

  First, the CPU 502 drives the belt drive motor 210 to start the rotation of the intermediate transfer belt 8 (S801). Then, the CPU 502 stops the meandering correction control by fixing the eccentric cam 208 at a position where the intermediate transfer belt 8 can be driven stably (S802). The position that can be stably driven is basically a position where the steering roller 10 is not tilted.

  Next, the CPU 502 clears the pulse count value C of the encoder 61 to C = 0 (S803), and acquires the edge data E that is the output value of the edge sensor 203 in synchronization with the pulse count of the encoder 61 ( S804). The acquired edge data E is stored in the RAM 504. Thereafter, the CPU 502 determines whether or not the total number of pulses for one rotation of the intermediate transfer belt 8 has been reached (S805).

FIG. 9 is a diagram illustrating the determination method in step S805.
First, the CPU 502 starts the pulse count of the encoder 61 with an arbitrary sampling start point S1 of the edge data E as a reference point, and counts 1920 pulses that is the assumed total number of pulses for one rotation of the intermediate transfer belt 8. This sampling start point S1 becomes the home position HP of the intermediate transfer belt 8.

  After counting 1920 pulses, the CPU 502 counts pulses until the output value of the edge sensor 203 is the same as the sampling start point S1, and the number of pulses at the point S2 (= S1) at which the output value of the same edge sensor 203 is obtained is belted. This is determined as the total number of pulses T per round. In the example of this figure, the total number of pulses T = 1922.

  If it is determined in step S805 in FIG. 8 that the total number of pulses T per rotation of the intermediate transfer belt 8 has not been reached, 1 is added to the pulse count value C (S806), and the process returns to step S804. If it is determined that the total number of pulses T for one rotation of the intermediate transfer belt 8 has been reached, the CPU 502 determines whether or not the edge data E for one rotation of the intermediate transfer belt 8 has been measured three times (S807).

  In step S807, when the measurement is not performed three times, the process returns to step S803, and the edge data E is measured with respect to the sampling start point S1 also for the second and third turns of the intermediate transfer belt 8. When the measurement is completed three times, the CPU 502 averages the edge data E for three times in each pulse count value (S808). Then, the CPU 502 stores the averaged edge data E as edge profile data P in the RAM 504 (S809).

  As shown in FIG. 10, the edge profile data P is stored in the memory address of the RAM 504 corresponding to the pulse count value. Here, the address is represented by a decimal number for convenience, and the pulse count value and the address are shown to be matched. However, as long as the pulse count value and the address are associated with each other, they may not be matched.

  When the storage of the edge profile data P in the RAM 504 is completed in step S809, the CPU 502 stops the rotation of the intermediate transfer belt 8 by stopping the driving of the belt drive motor 210 (S810), and this flow is finished. The edge profile data P obtained by the control according to this flowchart is used for meandering correction control of the intermediate transfer belt 8 during actual image formation.

FIG. 11 is a flowchart showing meandering correction control of the intermediate transfer belt.
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 (S1101). 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 (S1102).

  Next, the CPU 502 specifies the address of the RAM 504 corresponding to the pulse count value C of the encoder 61 (S1103). The address of the RAM 504 is as shown in FIG. The CPU 502 acquires the edge profile data P from the identified address on the RAM 504 (S1104), and acquires the edge data E that is the output value of the edge sensor 203 (S1105).

  Thereafter, the CPU 502 calculates the meandering amount D based on the edge profile data P and the edge data E as described in the explanation of FIG. 7 (S1106). 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 (S1107).

  Next, the CPU 502 determines whether or not to end the image forming operation (S1108). 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 S1108 that the image forming operation is to be terminated, the CPU 502 stops the rotation of the intermediate transfer belt 8 by stopping the driving of the belt driving motor 210 (S1113), and this flow is terminated.

  If it is determined in step S1108 that the image forming operation is not terminated, the CPU 502 waits until the next pulse from the encoder 61 is detected (S1109). When the next pulse from the encoder 61 is detected, the CPU 502 adds 1 to the pulse count value C (S1110), and determines whether or not the pulse count value C is equal to the total number of pulses T per belt revolution. (S1111). Here, the total number of pulses T per belt is as described in the calculation method with reference to FIG.

  If the pulse count value C is equal to the total number of pulses T per belt, the pulse count value C is cleared to C = 0 (S1112), and the process returns to step S1103 described above. On the other hand, when the pulse count value C is not equal to the total number of pulses T per belt, the process returns to step S1103 without clearing the pulse count value C.

  As described above, according to this embodiment, since the position of the intermediate transfer belt 8 can be specified based on the pulse count value C of the encoder 61, the HP mark on the intermediate transfer belt 8 and the HP mark are detected. There is no need to provide an HP sensor for this purpose. For this reason, according to the present embodiment, it is possible to shorten the time from the start of the driving of the intermediate transfer belt 8 until the meander correction control is performed, thereby improving productivity and realizing cost reduction. .

  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.

1 Image forming device 8 Intermediate transfer belt (corresponding to belt)
10 Steering roller 11 Drive roller 61 Encoder (corresponding to output means)
203 Edge sensor (corresponding to 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;
Detecting means for detecting the position of the end of the belt in the width direction orthogonal to the predetermined direction;
An output means for outputting a signal in synchronization with rotation of any one of the plurality of rollers;
Storage means for storing edge profile data indicating shape data for one round of the end of the belt in association with the count value of the signal output from the output means;
Control means for correcting meandering of the belt by inclining the axis of any one of the plurality of rollers,
The control means reads the edge profile data corresponding to the count value of the signal output from the output means from the storage means, and outputs the read edge profile data and the detection means during the rotational movement of the belt. The belt drive device calculates the meandering amount of the belt based on the edge data obtained by the above.   The control means detects the shape data for one round of the end of the belt using the detection means without tilting the axis of any one of the plurality of rollers, and detects the detection. 2. The belt driving apparatus according to claim 1, wherein shape data is stored in the storage means as the edge profile data.   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 1. 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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