JP2008241854A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of performing control so that the rotational speed of a roller may be aimed reference rotational speed even if a light shielding plate rotating synchronously with the roller is attached eccentrically. <P>SOLUTION: A measuring part 150 measures the first to fourth light receiving periods T1 to T4 being time when the light output from a light emitting part 421 is received by a light receiving part 422 through the first to fourth holes 411 to 414. A calculation part 160 calculates the first to fourth actual passing distances W1 to W4 being the actual passing distances of the light from the light emitting part 421 through the first to the fourth holes 411 to 414 on the basis of the first to the fourth light receiving periods T1 to T4 measured by the measuring part 150. A roller control part 170 controls a motor 180 so that the rotational speed of a tension roller 242 may be the prescribed reference rotational speed from the first to the fourth light receiving periods T1 to T4 and the first to the fourth actual passing distances W1 to W4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for controlling the speed of a roller provided in an image forming apparatus.

In Patent Literature 1, a reflective surface and a non-reflective surface are alternately formed along the outer periphery of the back surface, and are attached to the shaft of the motor, and are disposed on the back surface side of the code wheel that rotates synchronously with the shaft. An error when the code wheel is mounted eccentrically with respect to the shaft, with two sensors consisting of a light emitting element and a light receiving element, and obtaining the average of the outputs from both sensors as the true rotational speed of the motor An optical rotary encoder that compensates for the above is disclosed.
JP 2001-188017 A

  However, the method of Patent Document 1 compensates for an error in the rotational speed of the motor due to eccentricity by obtaining an average of outputs from two sensors, and employs a method completely different from the present invention.

  An object of the present invention is to provide a reference rotational speed that targets the rotational speed of a roller even when a light shielding plate that rotates synchronously with the roller is eccentrically mounted from the rotational axis of the roller included in the image forming apparatus. An image forming apparatus that can be controlled as described above is provided.

  An image forming apparatus according to the present invention rotates in synchronization with a roller and is output from a disk-shaped light-shielding plate in which a hole having a shape that becomes wider in the radial direction from the center, a light emitting unit, and the light emitting unit. A sensor means arranged so that a light receiving part for receiving the received light sandwiches the light shielding plate, and a measurement for measuring a light reception time in which the light output from the light emitting part is received by the light receiving part through the hole Means, a calculation means for calculating an actual passage distance that is an actual passage distance of the light of the light emitting portion based on the light reception time measured by the measurement means, and an actual passage calculated by the calculation means Roller control means for controlling the roller so that the rotation speed of the roller becomes a reference rotation speed based on the distance and the light receiving time is provided.

  According to this configuration, the disk-shaped light shielding plate that rotates in synchronization with the roller is formed with a hole having a shape that increases in width from the center toward the radial direction. Is arranged so as to sandwich the light shielding plate, and the light receiving time during which the light output from the light emitting unit is received by the light receiving unit through the hole is measured, and based on this light receiving time, the light from the light emitting unit is actually perforated The actual passing distance indicating the distance passing through is calculated, and the rotational speed of the roller is controlled from the actual passing distance and the light receiving time so that the actual rotational speed of the roller becomes the reference rotational speed.

  That is, since the hole formed in the light shielding plate has a shape that becomes wider in the radial direction, the light receiving time for the light receiving unit to receive the light from the light emitting unit through the hole is a roller. Therefore, the actual passing distance can be obtained based on the light receiving time. Then, by controlling the rotation speed of the roller so that the rotation speed obtained from the actual passing distance and the light receiving time becomes the reference rotation speed, the light shielding that rotates synchronously with the roller from the rotation shaft of the roller included in the image forming apparatus. Even when the plate is mounted eccentrically, it can be controlled so that the rotational speed of the roller becomes the target reference rotational speed.

  The holes are four holes of the first to fourth holes that are the same in size and shape and are arranged at regular intervals in the rotation direction of the light shielding plate, and are output from the light emitting unit. The first to fourth light receiving times during which the received light is received by the light receiving unit through the first to fourth holes are measured, and the calculating means connects the sensor means and the center of the roller. A straight line is set as the Y axis, a straight line parallel to the light shielding plate and orthogonal to the Y axis is set as the X axis, and the width of the first hole is determined using the first and third light receiving times. A first passage time from the center of the direction passing through the sensor means to the passage of the center of the width direction of the third hole through the sensor means is calculated, and based on the first passage time, When it is assumed that the first and third holes are shifted only from the center of the roller to the X axis, The first calculating means for calculating the first passing distance indicating the passing distance of the first and third holes of the light from the light emitting section, and the second and fourth light receiving times, and The second passage time from the time when the center in the width direction of the four holes passes through the sensor means to the time when the center in the width direction of the second hole passes through the sensor means is calculated. Based on the time, it is assumed that the second and fourth holes are deviated from the center of the roller only to the X-axis, and the passing distance of the light from the light emitting portion through the second and fourth holes Based on the second calculating means for calculating the second passing distance indicating the first light receiving time and the third light receiving time, the first hole and the third hole are connected to the roller. The first and third holes through which the light from the light-emitting portion passes when it is assumed that the center is shifted only in the Y-axis direction. Based on the third calculation means for calculating the third passing distance shown, the second light receiving time and the fourth light receiving time, the second hole and the fourth hole are A fourth calculating means for calculating a fourth passing distance indicating a passing distance of the light from the light emitting portion through the second and fourth holes when it is assumed that it is shifted only in the Y-axis direction from the center; 1st which shows the actual passage distance of the said 1st-4th hole of the light from the said light emission part based on the said 1st-4th passage distance calculated by the said 1st-4th calculation means -5th calculation means for calculating the 4th actual passage distance, The roller control means is the above-mentioned roller from the 1st-4th light reception time and the 1st-4th actual passage distance. It is preferable to control the roller so that the rotation speed of the roller becomes the reference speed.

  According to this configuration, the light shielding plate has the same size and shape, and includes the first to fourth holes arranged at regular intervals in the rotation direction of the light shielding plate, and is output from the light emitting unit. The first to fourth light receiving times when the received light is received by the light receiving unit through the first to fourth holes are measured. The first passage time from when the center in the width direction of the first hole passes through the sensor means until the center in the width direction of the third hole passes through the sensor means is calculated. Based on the time, it is assumed that the first and third holes indicate the passing distances of the first and third holes of the light from the light emitting unit when it is assumed that the first and third holes are shifted only from the center of the roller to the X axis. A passing distance of 1 is calculated.

  Further, a second passage time from the time when the center of the second hole in the width direction passes through the sensor means to the time when the center of the width direction of the fourth hole passes through the sensor means is calculated. Based on the passage time, the second and fourth holes indicate the passage distances of the second and fourth holes for light from the light emitting section when it is assumed that the second and fourth holes are shifted from the center of the roller only to the X axis. A passing distance of 2 is calculated.

  Further, the light emitting unit when it is assumed that the first hole and the third hole are displaced only in the Y-axis direction from the center of the roller based on the first light receiving time and the third light receiving time. A third passing distance indicating the passing distance of the light from the first and third holes is calculated. Further, based on the second light receiving time and the fourth light receiving time, from the light emitting unit when it is assumed that the second hole and the fourth hole are displaced only in the Y-axis direction from the center of the roller. A fourth passage distance indicating the passage distance of the second and fourth holes is calculated. And based on these 1st-4th passage distance, the 1st-4th real passage distance which shows the actual passage distance of the 1st-4th hole of the light from a light-emitting part is computed, and the 1st-1st The roller is controlled from the fourth light receiving time and the first to fourth actual passing distances so that the rotational speed of the roller becomes the reference speed. That is, since the rotation speed of the roller is controlled so that the speed is constant at the four positions corresponding to the first to fourth holes, the rotation speed of the roller can be controlled to the reference rotation speed with higher accuracy. It becomes possible.

  The first calculating means calculates the first passing distance by the calculation of the formula (A), and the second calculating means calculates the second passing distance by the calculation of the formula (B). It is preferable to do.

W1x = W3x = 2 · W · T13 / T (A)
W2x = W4x = 2 · W · T42 / T (B)
However, W1x shows the 1st passage distance in the 1st hole, W3x shows the 1st passage distance in the 3rd hole, and W is when the shading plate is not eccentric from the roller A predetermined passing distance of each of the first to fourth holes of the light from the light emitting unit is indicated, T13 indicates the first passing time, and T is a predetermined required for the light shielding plate to make one round. W2x and W4x indicate the second passing distance, and T42 indicates the second passing time.

  According to this configuration, the first passing distance is calculated by the calculation of the formula (A), and the second passing distance is calculated by the calculation of the formula (B). It is possible to calculate with high accuracy.

  Further, the first to fourth holes are formed in the light shielding plate so that an intersection of two sides in the radial direction is located at the center of the light shielding plate, and the third calculation means is represented by the formula (C) The amount of deviation of the first and third holes in the Y-axis direction from the center of the roller is calculated by the calculation of, and the third passage distance is calculated from the amount of deviation, and the fourth calculation means includes: It is preferable that a deviation amount in the Y-axis direction of the second and fourth holes from the center of the roller is calculated by the calculation of the equation (D), and the fourth passage distance is calculated from the deviation amount.

b = π · L (T1−T3) / θ · T (C)
c = π · L (T2−T4) / θ · T (D)
Where b represents the amount of displacement of the first and third holes in the Y-axis direction from the center of the roller, and c represents the displacement of the second and fourth holes in the Y-axis direction from the center of the roller. L represents a predetermined distance from the center of the roller to the position where the light from the light emitting unit passes through the first to fourth holes, and T1 to T4 represent the first to fourth light receiving times. And θ represents an angle formed by two sides in the radial direction in each of the first to fourth holes.

  According to this configuration, the amount of deviation in the Y-axis direction from the centers of the rollers of the first and third holes is calculated by the calculation of Expression (C), and the third passage distance is calculated from the amount of deviation. , The amount of deviation in the Y-axis direction from the centers of the rollers of the second and fourth holes is calculated by the calculation of equation (D), and the fourth passage distance is calculated from the amount of deviation, so 4 can be calculated with high accuracy.

  According to the present invention, even when the light shielding plate that rotates synchronously with the roller is eccentrically attached from the rotation shaft of the roller included in the image forming apparatus, the rotation speed of the roller becomes the target rotation speed. Can be controlled.

  FIG. 1 is a diagram schematically showing an internal configuration of an image forming apparatus according to an embodiment of the present invention. In this figure, an image forming apparatus 10 constitutes a tandem type color printer, and is disposed above a main body 12 for printing a color image on a recording paper (transfer paper). The recording paper discharging unit 14 is configured to discharge recording paper on which a color image is printed by the unit 12.

  The main body 12 includes a paper feed cassette 20 disposed in the lower portion of the housing 18, an image forming portion 22 disposed in the upper portion of the housing 18, and a lower portion of the image forming portion 22 in the housing 18. Are disposed between the sheet feeding cassette 20 and the transfer conveyance unit 24, the fixing unit 26 disposed on the downstream side of the transfer conveyance unit 24 in the housing 18, and the transfer conveyance unit 24. A first transport path 28 and a second transport path 30 disposed between the fixing unit 26 and the recording paper discharge unit 14 are provided.

  The paper feed cassette 20 is configured such that the recording paper can be replenished by being pulled out of the housing 18, and the recording paper accumulated inside is fed one by one by a paper feed roller (not shown). 1 is fed out to the conveyance path 28 side. Note that a predetermined number of the paper feeding cassettes 20 are arranged corresponding to the size of the recording paper.

  The image forming unit 22 is configured to multiplexly form a plurality of toner images on a recording sheet, and includes a first image forming unit 221 that forms a magenta toner image, and a second image forming that forms a cyan toner image. A unit 222, a third image forming unit 223 for forming a yellow toner image, and a fourth image forming unit 224 for forming a black toner image are arranged at predetermined intervals along the conveyance direction of the recording paper. It will be.

  Each of the image forming units 221 to 224 includes a photosensitive drum 225, a charging unit 226 disposed to face the peripheral surface of the photosensitive drum 225, and a downstream side of the charging unit 226 on the periphery of the photosensitive drum 225. An exposure unit 227 comprising an LED print head (for example, having a number of pixels of 7168 in the line direction) disposed opposite to the surface, and on the peripheral surface of the photosensitive drum 225 on the downstream side of the exposure unit 227. A developing device 228 disposed opposite to the developing device 228 and a cleaning unit 229 disposed downstream of the developing device 228 and opposed to the peripheral surface of the photosensitive drum 225 are provided. Further, the transfer unit 230 is formed by disposing a transfer roller 244 described later between the developing device 228 and the cleaning unit 229 on the peripheral surface of the photosensitive drum 225.

  The photosensitive drum 225 of each of the image forming units 221 to 224 is rotated in the clockwise direction shown in the figure by a drive motor (not shown). Further, the developing devices 228 of the first to fourth image forming units 221 to 224 are each provided with a toner box. The chromatic color magenta toner is supplied to the toner box of the first image forming unit 221, and the chromatic color cyan toner is supplied to the toner box of the second image forming unit 222. The 223 toner box stores a chromatic yellow toner, and the fourth image forming unit 224 stores an achromatic black toner.

  The transfer conveyance unit 24 includes a driven roller 241 disposed in the vicinity of the first image forming unit 221, a tension roller 242 disposed in the vicinity of the fourth image forming unit 224, and a driven roller 241. A transfer belt 243 that is an endless image carrier disposed across the tension roller 242 and a position downstream of the developing device 228 of the photosensitive drum 225 of each of the image forming units 221 to 224 via the transfer belt 243. Four transfer rollers 244 arranged so as to be able to be pressed against each other, a reflection type photosensor 245 arranged below the tension roller 242 in the vicinity of the transfer belt 243, and a transfer on the downstream side of the reflection type photosensor 245. And a blade 246 disposed at a position in contact with the belt 243.

  In the transfer conveyance unit 24, the recording paper conveyed from the first conveyance path 28 is electrostatically adsorbed onto a transfer belt 243 that rotates counterclockwise by a drive motor (not shown) and conveyed downstream. At the same time, the toner image is transferred to the recording paper at the position of the transfer unit 230 of each of the image forming units 221 to 224. The transfer belt 243 is made of a synthetic resin material having heat resistance such as a polyimide resin whose surface is coated with, for example, silicone.

  In addition, the reflection type photosensors 245 provided in the transfer conveyance unit 24 are disposed at both ends in the width direction (main scanning direction) orthogonal to the transfer direction of the transfer belt 243 and are formed on the transfer belt 243. Detect the density of the image.

  The reflection type photosensor 245 includes a light emitting unit configured by a light emitting diode that transmits light toward the transfer belt 243, and a light receiving unit configured by a photodiode that receives reflected light reflected by the transfer belt 243. And a detection circuit unit that converts the amount of reflected light received by the light receiving unit into a voltage value.

  The blade 246 is for scraping off deposits such as toner on the transfer belt 243, and is formed to have a length substantially the same as the width direction dimension of the transfer belt 243, and its tip is always the surface of the transfer belt 243. It is arrange | positioned in the state contact | abutted to. The blade 246 is kept away from the transfer belt 243 when it is not necessary to perform the scraping operation of the adhered matter, and the surface of the transfer belt 243 only when it is necessary to perform the scraping operation of the adhered matter. It is good also as a structure made to contact | abut.

  The fixing unit 26 performs a fixing process by heating the recording paper onto which the toner images formed on the surface of the photosensitive drum 225 of the image forming unit 22 are transferred, and includes a heat shield box 261 and a heat shield. A fixing roller 262 provided in the upper part of the box 261 and including a heater; a pressure roller 263 provided in pressure contact with the fixing roller 262 in the lower part of the heat shielding box 261; and the heat shielding box 261. A front conveyance path 264 that is disposed in front of the fixing roller 262 and the pressure roller 263 and guides the recording paper conveyed from the transfer conveyance unit 24 between the fixing roller 262 and the pressure roller 263, and a heat shielding box. A rear conveyance path 265 that is disposed behind the fixing roller 262 and the pressure roller 263 in the H.261 and guides the recording paper subjected to the fixing process to the second conveyance path 30. It is equipped with a.

  The first conveyance path 28 conveys the recording paper fed from the paper feed cassette 20 to the transfer conveyance unit 24 side, and includes a plurality of conveyance roller pairs 281 disposed at predetermined positions, and a transfer conveyance unit. 24, and a registration roller pair 282 for taking the timing of the image forming operation and the paper feeding operation of the image forming unit 22 is provided. The plurality of transport roller pairs 281 and the registration roller pairs 282 are each driven to rotate by an unillustrated drive motor via an electromagnetic clutch. A registration sensor 283 made of a photo interrupter or the like is disposed in front of the registration roller pair 282. When the leading edge of the recording paper is conveyed to the registration roller pair 282, an output signal from the registration sensor 283 is output. Based on this, the conveyance of the recording paper is temporarily stopped.

  The second transport path 30 transports the recording paper fixed by the fixing unit 26 to the recording paper discharge unit 14. A plurality of transport roller pairs 301 are disposed at predetermined positions, and are disposed on the exit side. A discharge roller pair 302 is disposed. The transport roller pair 301 and the discharge roller pair 302 are driven to rotate by an unillustrated drive motor via an electromagnetic clutch.

  The recording paper discharge unit 14 is formed integrally with the main body 12 on the upper surface of the casing 18 constituting the main body 12, and the recording paper that has been transported from the second transport path 30 and has undergone the fixing process is used. The images are sequentially accumulated so that the image-formed surface is on the back side.

  The image forming apparatus 10 configured as described above operates as follows. That is, in each photosensitive drum 225 of the image forming unit 22, an electrostatic region is formed on the surface by the charging unit 226, and the electrostatic region is exposed by the output light from the exposure unit 227, thereby static electricity based on the image data. An electrostatic latent image is formed, and then a toner image is formed by the developing device 228. Further, the fixing roller 262 of the fixing unit 26 is energized by applying a voltage to the built-in heater by a voltage supply unit (not shown), and is heated and controlled so that the surface of the fixing roller 262 reaches a fixing possible temperature.

  On the other hand, a recording paper of a specified size is fed out from the paper feed cassette, conveyed to the front of the registration roller pair 282 by the first conveyance path 28, and temporarily stopped. Then, the recording paper conveyed to the front of the registration roller pair 282 is conveyed to the transfer conveying unit 24 after timing with the image forming operation of the image forming unit 22, and each of the image forming units 221 to 224. Thus, the toner images are sequentially transferred onto the recording paper. In other words, the image is transferred in a state where the magenta toner, the cyan toner, the yellow toner, and the black toner are superimposed on each other on the recording paper.

  Then, the recording sheet on which the toner image is transferred is conveyed into the fixing unit 26, is heated by the fixing roller 262, is sandwiched between the fixing roller 262 and the pressure roller 263, and is conveyed to the downstream side. The paper is discharged to the recording paper discharge unit 14 through the conveyance path 30. The toner remaining on the surface of each photosensitive drum 225 having the toner image transferred to the recording paper is removed by the cleaning unit 229. This operation is sequentially repeated to execute printing on a predetermined number of recording sheets.

  2 and 3 are diagrams showing the positional relationship between the tension roller 242 and the light shielding plate 410. FIG. As shown in FIG. 2, a light shielding plate 410 is disposed at the longitudinal end of the tension roller 242. The light shielding plate 410 is composed of a disk-shaped member, and a cylindrical holder 415 into which the rotation shaft 242a of the tension roller 242 is fitted is formed at the center thereof. As a result, the light shielding plate 410 rotates in synchronization with the tension roller 242. A support member 416 for attaching the tension roller 242 to a housing (not shown) is disposed below the rotation shaft 242a. Above the light shielding plate 410, a photo interrupter 420 including a light emitting unit 421 that emits light and a light receiving unit 422 that receives light emitted from the light emitting unit 421 is disposed. Below the photo interrupter 420, a support member 430 for attaching the photo interrupter 420 to a housing (not shown) is attached. The light emitting unit 421 is disposed so as to face the light receiving unit 422 with the light shielding plate 410 interposed therebetween. The light shielding plate 410 has substantially fan-shaped first to fourth holes 411 to 414 that increase in width from the center O <b> 1 of the light shielding plate 410 toward the radial direction of the light shielding plate 410.

  As shown in FIG. 3, the first to fourth holes 411 to 414 have the same size and shape, and are arranged at a certain interval in the rotation direction A <b> 2 of the light shielding plate 410. That is, the first to fourth holes 411 to 414 are a straight line connecting the straight line L11 between the center and the center O1 in the width direction of the first hole 411 and the straight line between the center and the center O1 in the width direction of the second hole 412. An angle θ1 formed by L12, an angle θ2 formed by the straight line L13 and the straight line L13 connecting the center in the width direction of the third hole 413 and the center O1, and a straight line L14 connecting the straight line L13, the fourth hole 414 and the center O1 And an angle θ4 formed between the straight line L14 and the straight line L11 are 90 degrees. A position P1 illustrated in FIG. 3 indicates a position where the light receiving unit 422 receives the light emitted from the light emitting unit 421. The first to fourth holes 411 to 414 are formed in the light shielding plate 410 so that the intersection of the radial side 410a and the side 410b is the center O1.

  As described above, since the first to fourth holes 411 to 414 that are widened in the radial direction are formed in the light shielding plate 410, when the center O1 is eccentric with respect to the center O2, the degree of the eccentricity. Accordingly, the first to fourth light receiving times T1 to T4 change. Therefore, the rotation speed of the tension roller 242 is controlled to the reference speed by measuring the first to fourth light receiving times T1 to T4. It becomes possible.

  FIG. 4 is a block diagram illustrating an electrical configuration of the image forming apparatus 10. The image forming apparatus 10 includes a sensor unit 110, a LAN communication unit 120, an image processing unit 130, a control unit 140, a motor 180, a display unit 190, an image forming unit 191, an LUT storage unit 192, and a tension roller 242.

  The sensor unit 110 includes a photo interrupter 420 shown in FIGS. The LAN communication unit 120 is configured by a LAN (Local Area Network) interface, and receives image data transmitted according to a LAN communication protocol from a terminal device (not shown) connected via the LAN under the control of the control unit 140. Receive.

  The image processing unit 130 performs predetermined image processing such as gamma correction on the image data received by the LAN communication unit 120. The control unit 140 includes a microcomputer such as a CPU, a ROM, and a RAM, and governs overall control of the image forming apparatus 10. The control unit 140 includes functions of a measurement unit 150, a calculation unit 160, and a roller control unit 170. . These functions are realized by the CPU executing a control program stored in the ROM.

  The measuring unit 150 calculates first to fourth light receiving times T1 to T4, which are times when the light output from the light emitting unit 421 is received by the light receiving unit 422 through the first to fourth holes 411 to 414. taking measurement. Here, the measurement unit 150 specifies the first received light time T1 as the first received light time T1 after starting the measurement of the received light time, and specifies the second received light time as the fourth received light time T4. Then, the third light reception time acquired is specified as the third light reception time T3, and the fourth light reception time acquired is specified as the second light reception time T2.

  The calculating unit 160 is the actual passing distance of the first to fourth holes 411 to 414 of the light of the light emitting unit 421 based on the first to fourth light receiving times T1 to T4 measured by the measuring unit 150. The first to fourth actual passage distances W1 to W4 are calculated, and first to fifth calculation units 161 to 165 are provided.

  As shown in FIGS. 5 and 6, the first calculation unit 161 sets a straight line connecting the position P1 of the sensor unit 110 and the center O2 of the tension roller 242 as the Y axis, is parallel to the light shielding plate 410, and A straight line perpendicular to the Y axis is set as the X axis, and the third hole is formed after the center in the width direction of the first hole 411 passes through the position P1 using the first and third light receiving times T1 and T3. The first passage time T13 until the center of the width direction of 413 passes through the position P1 of the sensor unit 110 is calculated, and the first and third holes 411 and 413 are calculated based on the first passage time T13. First passing distances W1x and W3x indicating the passing distances of the first and third holes 411 and 413 of the light from the light emitting portion 421 when it is assumed that the tension roller 242 is shifted only from the center O2 to the X axis. (= W1x) is calculated.

  Here, the 1st calculation part 161 calculates 1st passage distance W1x and W3x by the calculation of Formula (A).

W1x = W3x = 2 · W · T13 / T (A)
However, W indicates a predetermined passing distance of each of the first to fourth holes 411 to 414 of the light from the light emitting portion 421 when the light shielding plate 410 is not eccentric from the tension roller 242, and T13 is the first passage. Time indicates T, and a predetermined period required until the light shielding plate 410 makes one round.

  When the first and third holes 411 and 413 are shifted from the center O2 of the tension roller 242 only to the X axis, the center line C11 in the width direction of the first and third holes 411 and 413 is Y. This means that the center O1 of the light shielding plate 410 is located on the X axis other than X = 0 when it is parallel to the axis.

  As shown in FIGS. 5 and 6, the second calculation unit 162 uses the second and fourth light receiving times T2 and T4, and the center in the width direction of the fourth hole 414 is the position P1 of the sensor unit 110. The second passage time T42 from the passage of the second passage 412 until the center of the second hole 412 in the width direction passes through the sensor unit 110 is calculated. Based on the second passage time T42, the second and fourth passage times T42 are calculated. 2nd indicating the passage distance of the light from the light emitting portion 421 through the second and fourth holes 412 and 414 when it is assumed that the holes 412 and 414 are deviated only from the center O2 of the tension roller 242 to the X axis. The passing distances W2x and W4x are calculated.

  Here, the 2nd calculation part 162 calculates 2nd passage distance W2x and W4x by the calculation of Formula (B).

W2x = W4x = 2 · W · T42 / T (B)
When the second and fourth holes 412 and 414 are shifted from the center O2 of the tension roller 242 only to the X axis, the center line C12 in the width direction of the second and fourth holes 412 and 414 is Y. This refers to the case where the center O1 of the light shielding plate 410 is located on the X axis other than X = 0 when it is parallel to the axis.

  Based on the first light reception time T1 and the third light reception time T3, the third calculation unit 163 has the first hole 411 and the third hole 413 only in the Y-axis direction from the center O2 of the tension roller 242. The third passing distances W1y and W3y indicating the passing distances of the first and third holes 411 and 413 of the light from the light emitting portion 421 when calculated as being shifted to the above are calculated.

  The case where the first hole 411 and the third hole 413 are displaced only in the Y-axis direction from the center O2 of the tension roller 242 is the center line in the width direction of the first and third holes 411 and 413. This indicates a case where the center O1 of the light shielding plate 410 is located on the Y axis other than Y = 0 when C11 is parallel to the Y axis.

  Here, the third calculation unit 163 calculates the amount of displacement b in the Y-axis direction of the first and third holes 411 and 413 with respect to the center O2 of the tension roller 242 by the calculation of Expression (C), and this displacement The third passage distances W1y and W3y are calculated from the quantity b.

b = π · L (T1−T3) / θ · T (C)
Here, L represents a predetermined distance from the center O2 of the tension roller 242 to the position P1, and θ represents a predetermined angle formed by the two radial sides 410a and 410b in each of the first to fourth holes 411 to 414. Show.

  Here, the third calculation unit 163 calculates the third passage distance W1y using the equation (E), and calculates the third passage distance W3y using the equation (F).

W1y = (L + b) · W / L (E)
W3y = (L−b) · W / L (F)
Based on the second light reception time T2 and the fourth light reception time T4, the fourth calculation unit 164 has the second hole 412 and the fourth hole 414 only in the Y-axis direction from the center O2 of the tension roller 242. The fourth passing distances W2y and W4y indicating the passing distances of the second and fourth holes 412 and 414 of the light from the light emitting portion 421 when calculated as being shifted to the above are calculated.

  Note that the case where the second hole 412 and the fourth hole 414 are displaced only in the Y-axis direction from the center O2 of the tension roller 242 is the center line in the width direction of the second and fourth holes 412 and 414. This indicates a case where the center O1 of the light shielding plate 410 is located on the Y axis other than Y = 0 when C11 is parallel to the Y axis.

  Here, the fourth calculation unit 164 calculates the shift amount c in the Y-axis direction of the second and fourth holes 412 and 414 with respect to the center O2 of the tension roller 242 by the calculation of Expression (D), and this shift The fourth passage distances W2y and W2y are calculated from the quantity c.

c = π · L (T2−T4) / θ · T (D)
Here, the fourth calculation unit 164 calculates the fourth passage distance W2y using the equation (G), and calculates the fourth passage distance W4y using the equation (H).

W2y = (L + c) · W / L (G)
W4y = (L−c) · W / L (H)
The fifth calculating unit 165 stores the first passing distance W1x calculated by the first calculating unit 161 and the third passing distance W1y calculated by the third calculating unit 163 in the LUT storage unit 192. The first actual passage distance W1 is calculated with reference to the stored lookup table.

  In addition, the fifth calculation unit 165 includes an LUT storage unit based on the first passage distance W3x calculated by the first calculation unit 161 and the third passage distance W3y calculated by the third calculation unit 163. The third actual passing distance W3 is calculated with reference to the lookup table stored in 192.

  In addition, the fifth calculation unit 165 uses the LUT storage unit from the second passage distance W2x calculated by the second calculation unit 162 and the fourth passage distance W2y calculated by the fourth calculation unit 164. Referring to the lookup table stored in 192, the second actual passing distance W2 is calculated.

  In addition, the fifth calculation unit 165 calculates the LUT storage unit from the second passage distance W4x calculated by the second calculation unit 162 and the fourth passage distance W4y calculated by the fourth calculation unit 164. The fourth actual passing distance W4 is calculated with reference to the lookup table stored in 192. 5 and 6, W1 to W4 are not shown.

  From the first to fourth light receiving times T1 to T4 and the first to fourth actual passing distances W1 to W4, the roller controller 170 adjusts the rotational speed of the tension roller 242 to a predetermined reference rotational speed v0. The motor 180 is controlled. That is, the roller control unit 170 adjusts the rotation speed of the motor 180 so that the first light reception time T1 is W1 / v0, and the motor control unit 170 adjusts the rotation speed of the motor 180 so that the second light reception time T2 is W2 / v0. The rotation speed is adjusted, the rotation speed of the motor 180 is adjusted so that the third light reception time T3 becomes W3 / v0, and the rotation speed of the motor 180 so that the fourth light reception time T4 becomes W4 / v0. Adjust.

  The motor 180 rotates the tension roller 242 under the control of the roller control unit 170. The display unit 190 is composed of a liquid crystal display panel or the like, and displays various information indicating the operating state and the like of the image forming apparatus 10. The image forming unit 191 includes the image forming unit 22 shown in FIG. 1 and forms a toner image on the transfer belt.

  The LUT storage unit 192 includes a first actual passing distance W1, a first passing distance W3x, and a third passing distance W3y that are predetermined according to the values of the first passing distance W1x and the third passing distance W1y. A third actual passing distance W3 predetermined according to the value of the second, a second actual passing distance W2 predetermined according to the values of the second passing distance W2x and the fourth passing distance W2y, A look-up table is stored which stores a fourth actual passing distance W4 predetermined in accordance with the values of the second passing distance W4x and the fourth passing distance W4y in a table format. The relationship between W1 to W4 and W1x, W1y, W2x, W2y, W3x, W3y, W4x, W4y obtained in advance by experiment is adopted. Further, since the relationship between W1, W1x, and W1y is equal to the relationship between W2 and W2x, W2y, the relationship between W3 and W3x, W3y, and the relationship between W4, W4x, and W4y, the LUT storage unit 192 Only the relationship between W1 and W1x, W1y needs to be stored.

  FIG. 5 is a view showing the light shielding plate 410 when the first and third holes 411 and 413 are displaced only in the Y-axis direction. FIG. 6 is a view showing the light shielding plate 410 when the second and fourth holes 412 and 414 are displaced only with respect to the X axis.

  As shown in FIG. 5, the first and third holes 411 and 413 are located on the Y axis where the center O1 is other than Y = 0 when the center line C11 in the width direction is parallel to the Y axis. Therefore, it is shifted only with respect to the Y axis. Therefore, the first passage time T13 is T13 = T / 2.

  On the other hand, as shown in FIG. 6, when the center line C12 in the width direction of the second and fourth holes 412 and 414 is parallel to the Y axis, the center O1 is located on the X axis other than X = 0. Therefore, it is shifted only with respect to the X axis. Therefore, the second passage time T42 ≠ T / 2. Specifically, in the case of FIG. 6, since the center O1 is X <0 when the center line C12 is parallel to the Y axis, the second and fourth holes 412 and 414 have T42> T / 2. Become.

  Here, when the second and fourth holes 412 and 414 are not displaced with respect to the X axis, the actual passing distance of the second and fourth holes 412 and 414 is W, and the second and fourth holes 412. , 414 is deviated only with respect to the X axis, the actual passing distance of the second and fourth holes 412 and 414 is W ′, and the relationship of W: T / 2 = W ′: T42 is established. '= 2 · W · T42 / T is obtained. Then, assuming that W ′ is the second passage distances W2x and W4x when it is assumed that the second and fourth holes 412 and 414 are displaced only with respect to the X axis, the above formula (B) is obtained. .

  Further, if the actual passing distance of the first hole 411 shown in FIG. 5 is W ″, the first and third holes 411 and 413 are shifted to the third hole 413 side. W ″ = W + (b / L) · W. On the other hand, if the actual passing distance of the third hole 413 is W ′ ″, the first and third holes 411 and 413 are shifted to the third hole 413 side. ″ = W− (b / L) · W. Here, if the time required for W is t, the first light receiving time T1 is expressed as T1 = ((L + b) / L) · t, and the third light receiving time T3 is T3 = ((L−b ) / L) · t. Then, t = (θT) / 2π is obtained from t / T = θ / 2π, and this equation is substituted into the equations of T1 and T3 to obtain T1-T3. Then, T1-T3 = (2b / L) · ( (ΘT) / 2π)) = b · θ · T / (π · L) is obtained, and the equation (C) is obtained.

  Then, in FIG. 5, when W ″ is obtained using the deviation amount b obtained from the equation (C), the relationship of W ″ :( L + b) = W: L is established. ″ = (L + b) · W / L. Further, in FIG. 5, when W ″ ′ is obtained, the relationship W ″ ″ :( L−b) = W: L is established, and therefore W ″ ″ is W ′ ″ = (L−b). -W / L. When W ″ is the third passage distance W1y and W ″ is the third passage distance W3y, the above equations (E) and (F) are obtained.

  In FIG. 6, assuming that the first and third holes 411 and 413 are displaced only with respect to the X axis, and the actual passing distance of the first and third holes 411 and 413 is W ′, W: The relationship of T / 2 = W ′: T13 holds, and W ′ = 2 · W · T13 / T is obtained. Then, assuming that W ′ is the first passage distances W1x and W3x when it is assumed that the first and third holes 411 and 413 are displaced only with respect to the X axis, the equation (A) is obtained.

  Further, in FIG. 5, it is assumed that the second and fourth holes 412 and 414 are displaced only with respect to the Y axis, and the displacement amount of the second and fourth holes 412 and 414 with respect to the Y axis at this time is c. Assuming that the actual passage distance of the fourth hole 414 is W ″ and the actual passage distance of the second hole 412 is W ″ ″, c = π · L (T2−T4) / θ · T is obtained.

  Then, when W ″ is obtained using the deviation amount c obtained from the equation (D), the relationship of W ″ :( L + c) = W: L is established, and therefore W ″ is W ″ = ( L + c) · W / L. Further, when W ″ ′ is obtained, the relationship of W ″ ″ :( L−c) = W: L is established, and therefore W ″ ″ is W ′ ″ = (L−c) · W / L. It becomes. When W ″ is the fourth passage distance W4y and W ″ is the fourth passage distance W2y, the equations (H) and (G) are obtained.

  Next, processing by the image forming apparatus 10 will be described. FIG. 7 is a flowchart showing the operation of the image forming apparatus 10. First, in step S1, when the motor 180 is driven by the roller control unit 170 and the tension roller 242 is driven, in step S2, the measurement unit 150 uses the measurement results obtained by the sensor unit 110 to perform first to fourth. The light receiving times T1 to T4 are measured.

  Next, in step S3, the first calculator 161 calculates the first passage time T13 using the first and third light receiving times T1 and T3. Next, in step S4, the second calculation unit 162 calculates a second passage time T42 using the second and fourth light reception times T2 and T4.

  Next, in Step S5, the first calculation unit 161 performs the calculation of Expression (A) to calculate the first passage distances W1x and W3x. Next, in step S6, the second calculation unit 162 calculates the second passage distances W2x and W4x by the calculation of the formula (B).

  Next, in step S7, the third calculation unit 163 calculates a deviation amount b in the Y-axis direction from the center O2 of the tension roller 242 of the first and third holes 411 and 413 by the calculation of Expression (C). To do.

  Next, in step S8, the third calculation unit 163 calculates the third passage distance W1y using the equation (E), and calculates the third passage distance W3y using the equation (F).

  Next, in step S9, the fourth calculation unit 164 calculates the shift amount c in the Y-axis direction from the center O2 of the tension roller 242 of the second and fourth holes 412 and 414 by the calculation of the equation (D). calculate. Next, in step S10, the fourth calculation unit 164 calculates the fourth passage distance W2y using the equation (G), and calculates the fourth passage distance W4y using the equation (H).

  Next, in step S11, the fifth calculation unit 165 refers to the lookup table, and determines the first and third actual passing distances from the first passing distances W1x and W3x and the third passing distances W1y and W3y. W1 and W3 are calculated, and the second and fourth actual passing distances W2 and W4 are calculated from the second passing distances W2x and W4x and the fourth passing distances W2y and W4y.

  Next, in step S12, the roller controller 170 determines that the rotation speed of the tension roller 242 is a predetermined reference from the first to fourth light receiving times T1 to T4 and the first to fourth actual passing distances W1 to W4. The motor 180 is controlled so that the rotational speed becomes v0.

  As described above, according to the image forming apparatus 10, the first to fourth holes 411 to 414 formed in the light shielding plate 410 have shapes that become wider in the radial direction. The first to fourth light receiving times T1 to T4 in which the part 422 receives light from the light emitting part 421 through the first to fourth holes 411 to 414 correspond to the amount of eccentricity of the light shielding plate 410 with respect to the tension roller 242. Therefore, the first to fourth actual passage distances W1 to W4 can be obtained based on the first to fourth light receiving times T1 to T4. The rotation speed of the tension roller 242 is controlled so that the rotation speed obtained from the passage distances W1 to W4 and the first to fourth light receiving times T1 to T4 becomes the reference rotation speed v0. Therefore, even when the center O1 of the light shielding plate 410 is mounted eccentrically from the center O2 of the tension roller 242, it is accurately controlled so that the rotational speed of the tension roller 242 becomes the target reference rotational speed v0. can do.

  In the above embodiment, the light shielding plate 410 has four holes. However, the present invention is not limited to this, and the light shielding plate 410 may have two, three, five or more holes. In the above-described embodiment, the image forming apparatus 10 controls the rotation speed of the tension roller 242. However, the present invention is not limited to this, and the rotation speed of other rollers is controlled in the same manner as the tension roller 242. Also good.

1 is a diagram schematically showing an internal configuration of an image forming apparatus according to an embodiment of the present invention. It is the figure which showed the arrangement | positioning relationship between a tension roller and a light-shielding plate. It is the figure which showed the arrangement | positioning relationship between a tension roller and a light-shielding plate. 1 is a block diagram illustrating an electrical configuration of an image forming apparatus. It is the figure which showed the light-shielding plate in case the 1st and 3rd hole has shifted | deviated only with respect to the Y-axis direction. It is the figure which showed the light-shielding plate in case the 2nd and 4th hole has shifted | deviated only with respect to the X-axis. 3 is a flowchart illustrating an operation of the image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 110 Sensor part 120 LAN communication part 130 Image processing part 140 Control part 150 Measurement part 160 Calculation part 161-165 1st-5th calculation part 170 Roller control part 180 Motor 190 Display part 191 Image formation part 192 LUT Storage part 410 Light-shielding plates 411 to 414 First to fourth holes 421 Light emitting part 422 Light receiving parts W1 to W4 First to fourth actual passage distances W1x, W3x First passage distances W2x, W4x Second passage distances W1y , W3y Third passage distance W2y, W4y Fourth passage distance

Claims (4)

A disk-shaped light shielding plate in which a hole having a shape that rotates in synchronization with the roller and widens in the radial direction from the center;
Sensor means arranged such that a light emitting unit and a light receiving unit that receives light output from the light emitting unit sandwich the light shielding plate,
Measuring means for measuring a light receiving time during which the light output from the light emitting unit is received by the light receiving unit through the hole;
Based on the light reception time measured by the measuring means, calculating means for calculating an actual passing distance that is an actual passing distance of the hole of the light of the light emitting unit;
An image forming apparatus comprising: a roller control unit configured to control the roller so that a rotation speed of the roller becomes a reference rotation speed based on the actual passing distance calculated by the calculation unit and the light reception time. The holes are four holes of the first to fourth holes that have the same size and shape and are arranged at a certain interval in the rotation direction of the light shielding plate.
Measuring the first to fourth light receiving times when the light output from the light emitting unit is received by the light receiving unit through the first to fourth holes;
The calculating means includes
A straight line connecting the sensor means and the center of the roller is set as the Y axis, and a straight line parallel to the light shielding plate and orthogonal to the Y axis is set as the X axis, and the first and third light receiving times are set. Is used to calculate the first passage time from when the center in the width direction of the first hole passes through the sensor means until the center in the width direction of the third hole passes through the sensor means. Based on the first transit time, the first and third light beams from the light-emitting portion when the first and third holes are assumed to be shifted only from the center of the roller to the X axis. First calculating means for calculating a first passing distance indicating a passing distance of three holes;
Using the second and fourth light receiving times until the center in the width direction of the fourth hole passes through the sensor means until the center in the width direction of the second hole passes through the sensor means. When the second passage time is calculated, and based on the second passage time, it is assumed that the second and fourth holes are shifted only from the center of the roller to the X axis. Second calculating means for calculating a second passing distance indicating the passing distance of the light from the second and fourth holes;
Based on the first light reception time and the third light reception time, when it is assumed that the first hole and the third hole are shifted only in the Y-axis direction from the center of the roller, Third calculating means for calculating a third passing distance indicating a passing distance of the first and third holes of the light from the light emitting unit;
Based on the second light receiving time and the fourth light receiving time, it is assumed that the second hole and the fourth hole are shifted only in the Y-axis direction from the center of the roller. Fourth calculating means for calculating a fourth passing distance indicating a passing distance of the second and fourth holes of the light from the light emitting unit;
Based on the first to fourth passage distances calculated by the first to fourth calculation means, first to first indicating actual passage distances of the first to fourth holes of light from the light emitting unit. A fifth calculating means for calculating a fourth actual passing distance,
The roller control means controls the roller based on the first to fourth light receiving times and the first to fourth actual passing distances so that the rotation speed of the roller becomes the reference speed. The image forming apparatus according to claim 1. The first calculating means calculates the first passing distance by the calculation of the formula (A),
The image forming apparatus according to claim 2, wherein the second calculation unit calculates the second passage distance by an operation of an expression (B).
W1x = W3x = 2 · W · T13 / T (A)
W2x = W4x = 2 · W · T42 / T (B)
However, W1x shows the 1st passage distance in the 1st hole, W3x shows the 1st passage distance in the 3rd hole, and W is when the shading plate is not eccentric from the roller A predetermined passing distance of each of the first to fourth holes of the light from the light emitting unit is indicated, T13 indicates the first passing time, and T is a predetermined required for the light shielding plate to make one round. W2x indicates the second passing distance in the second hole, W4x indicates the second passing distance in the fourth hole, and T42 indicates the second passing time. The first to fourth holes are formed in the light shielding plate so that an intersection of two sides in the radial direction is located at the center of the light shielding plate,
The third calculation means calculates a deviation amount in the Y-axis direction of the first and third holes from the center of the roller by the calculation of Expression (C), and the third passage distance is calculated from the deviation amount. To calculate
The fourth calculation means calculates a deviation amount in the Y-axis direction of the second and fourth holes from the center of the roller by the calculation of Expression (D), and the fourth passage distance is calculated from the deviation amount. 4. The image forming apparatus according to claim 2, wherein the image forming apparatus is calculated.
b = π · L (T1−T3) / θ · T (C)
c = π · L (T2−T4) / θ · T (D)
Where b represents the amount of displacement of the first and third holes in the Y-axis direction from the center of the roller, and c represents the displacement of the second and fourth holes in the Y-axis direction from the center of the roller. L represents a predetermined distance from the center of the roller to the position where the light from the light emitting unit passes through the first to fourth holes, and T1 to T4 represent the first to fourth light receiving times. And θ represents an angle formed by two sides in the radial direction in each of the first to fourth holes.

Images