JP2013105110A - Image forming apparatus, and correction method and correction program for aligning transfer image and sheet in the same apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that effectively suppresses power consumption in aligning a sheet relative to a transfer image by using timing rollers.SOLUTION: When a sheet M reaches timing rollers 31 and 32, power supply to a timing roller driving motor 33 is interrupted. The sheet that has reached the timing rollers 31 and 32 is stopped by the timing rollers, and the amount D of the leading edge of the sheet sticking out of a nip part is measured. A relative position of at least one of a transfer image and the sheet to the other is corrected on the basis of the measured amount of stick-out.

Description

  The present invention relates to an image forming apparatus such as an MFP (Multi Function Peripherals) provided with a timing roller for aligning the sheet with respect to an image transferred to a sheet conveyed from a sheet feeding unit, and a transferred image in the apparatus. And an alignment correction program for causing a computer of the image forming apparatus to execute the alignment correction method.

  In an image forming apparatus such as an MFP, which is a multifunction digital image forming apparatus, as is well known, for example, an image (toner image) on an intermediate transfer belt is transferred to an appropriate position on a sheet conveyed from a sheet feeding cassette. As shown, a timing roller that is rotationally driven by a stepping motor or a brushless motor is disposed upstream of the transfer position in the paper transport direction. When the paper is detected by a timing sensor near the upstream of the timing roller, the timing roller The paper is temporarily stopped, and the timing of restarting the timing roller after the transfer is controlled.

  Specifically, when the transported paper is temporarily stopped by the timing roller, the timing is kept while the motor is in an excited state so that the leading edge of the paper (especially thick paper) does not protrude from the nip portion of the timing roller. Skew correction is performed by applying a holding force (hold function) to the roller and applying a leading edge of the sheet to the nip portion of the timing roller to create a bend (loop).

  Conventionally, in a copying machine in which the driving of the timing roller can be controlled independently of the other driving, the timing roller driving means is constituted by a constant current driving type stepping motor, and when the stepping motor is held. By providing a current switching means that sets the set current higher than the set current at the time of rotation, power consumption is suppressed, and further, from the time of passage to the transfer position by a transfer paper detection sensor arranged downstream of the timing roller. There has been proposed a technique for correcting the positional deviation of the paper (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 9-2335048

  However, as described above, when the hold function is applied so that the leading edge of the sheet does not jump out of the nip portion of the timing roller, the timing roller drive motor remains excited during this time and power is consumed. There was a problem.

  In the technique described in Patent Document 1, the current value of the stepping motor at the time of paper conveyance driving is made larger than that at the time of holding, in other words, the power consumption at the time of holding is reduced. Therefore, it does not change that electric power is consumed.

  The present invention has been made in view of the above circumstances, and an image forming apparatus capable of effectively suppressing power consumption when aligning a sheet with a transfer image by a timing roller, and aligning a transfer image and a sheet in the apparatus It is an object of the present invention to provide a correction method and an alignment correction program for causing a computer of an image forming apparatus to execute the alignment correction method.

The above problem is solved by the following means.
(1) A conveyance roller that conveys a sheet fed from a sheet feeding unit and an upstream side of a transfer position of an image onto the sheet conveyed by the conveyance roller, and temporarily stops the sheet and transfers it to the sheet A timing roller that aligns the sheet with respect to the transferred image, a motor that rotationally drives the timing roller, and that is powered off when the sheet reaches the timing roller, and stops at the timing roller A pop-out amount measuring means for measuring the pop-out amount from the nip portion of the leading edge of the paper, and a relative position with respect to at least one of the transfer image and the paper based on the pop-out amount measured by the pop-out amount measuring means An image forming apparatus comprising: correction means for correcting
(2) The image forming apparatus according to (1), wherein the correction unit corrects the relative position by delaying a start timing of the timing roller by the motor in accordance with the pop-out amount measured by the pop-out amount measuring unit. .
(3) The correction unit corrects the relative position by slowing a rotation speed when the timing roller is started by the motor for a predetermined period according to the pop-out amount measured by the pop-out amount measuring unit. Or the image forming apparatus according to 2;
(4) The correction unit corrects the relative position by delaying the timing of the electrostatic latent image writing operation for image formation according to the pop-out amount measured by the pop-out amount measuring unit. The image forming apparatus according to any one of?
(5) The image forming apparatus according to any one of (1) to (4), wherein the pop-out amount measuring unit includes an encoder that detects a rotation speed of the motor and outputs a pulse.
(6) The image forming apparatus according to any one of the preceding items 1 to 5, wherein the correction unit corrects the pop-out amount measured by the pop-out amount measuring unit according to a durable usage amount of the timing roller.
(7) The paper which does not pop out depending on the type of paper is used as a correction-unnecessary sheet, and the correction unit does not correct the alignment of the transfer image and the sheet with respect to the correction-unnecessary sheet. The image forming apparatus according to any one of the above.
(8) The image according to item 7 above, wherein the correction unit does not correct the alignment between the transfer image and the sheet even when the sheet is a sheet other than the correction-unnecessary sheet and the humidity condition is a certain level or higher. Forming equipment.
(9) The image forming apparatus according to (7) or (8), wherein the pop-out amount measuring unit does not measure the pop-out amount for the correction-unnecessary paper when the paper type is a correction-unnecessary paper.
(10) A transport roller that transports the paper fed from the paper feed unit and an upstream side of the transfer position of the image onto the paper transported by the transport roller, temporarily stops the paper and transfers it to the paper A method for correcting the alignment of a transfer image and a sheet in an image forming apparatus, comprising: a timing roller that aligns the sheet with respect to the transferred image; and a motor that rotationally drives the timing roller, wherein the sheet is a timing roller In the step of cutting off the power supply to the motor when reaching the position, the pop-out amount measuring step for measuring the pop-out amount from the nip portion of the leading edge of the paper stopped by the timing roller, and the pop-out amount measuring step Correction for correcting the relative position of the transfer image and at least one of the sheets based on the measured pop-out amount Alignment correction method for transferring image and the paper in the image forming apparatus characterized by comprising: a step, the.
(11) A conveyance roller that conveys the sheet fed from the sheet feeding unit and an upstream side of the transfer position of the image onto the sheet conveyed by the conveyance roller, the sheet is temporarily stopped and transferred to the sheet A program for aligning a transfer image and a sheet for execution by a computer of an image forming apparatus, comprising: a timing roller that aligns the sheet with respect to the transferred image; and a motor that rotationally drives the timing roller. A step of shutting off the power supply to the motor when the paper reaches the timing roller; a pop-out amount measuring step for measuring a pop-out amount from the nip portion of the leading edge of the paper stopped by the timing roller; Based on the pop-out amount measured in the pop-out amount measuring step, at least one of the transfer image and the paper Relative positions to correct the correction step and, the transferred image and the sheet registration correction program causing the computer to perform the.

  According to the invention described in item (1), when the paper reaches the timing roller, the power supply to the motor is cut off. For this reason, the leading edge of the sheet may jump out from the nip portion of the timing roller. The relative position of the transferred image and at least one of the paper is corrected.

  That is, when the paper reaches the timing roller, the hold function for exciting the timing roller driving motor is not used, so that no hold power is required and the power consumption of the motor is reduced. In addition, since the relative position of the transfer image and at least one of the sheets is corrected based on the measured pop-out amount, the image can be transferred to the appropriate position on the sheet as in the conventional case.

  According to the invention described in item (2) above, since the start timing of the timing roller by the motor is delayed according to the measured pop-out amount, the relative position with respect to at least one of the transfer image and the paper is appropriately set. Can be corrected.

  According to the invention described in item (3) above, the rotational speed at the start of the timing roller by the motor is delayed for a predetermined period in accordance with the measured amount of paper pop-out. The relative position can be corrected appropriately.

  According to the invention described in item (4) above, the timing of the electrostatic latent image writing operation for image formation is delayed in accordance with the measured amount of protruding paper, so that at least one of the transferred image and the paper The relative position with respect to the other can be corrected appropriately.

  According to the invention described in item (5) above, since the paper pop-out amount measuring means is an encoder, it is possible to easily determine the pop-out amount by counting the number of pulses from the encoder, and the encoder is built in the motor. For example, as a pop-out amount measuring means, it is possible to implement with a simple configuration utilizing the conventional structure rather than introducing a line sensor.

  According to the invention described in item (6) above, since the measured amount of jumping out of the paper is corrected by the durable usage of the timing roller, the transfer image and the paper are not affected by the durable usage of the timing roller. The relative position with respect to at least one of the other can be corrected more appropriately.

  According to the invention described in item (7), for example, correction processing of the relative position between the transfer image and the sheet is not performed wastefully on a correction-unnecessary sheet such as plain paper that is unlikely to pop out. .

  According to the invention described in item (8) above, even for a paper other than the correction unnecessary paper, for example, a thick paper, the relative position between the transfer image and the paper is not corrected if the humidity is higher than a certain level.

  According to the invention described in item (9), if the paper is a sheet that does not require correction, the pop-out amount is not measured by the pop-out amount measuring means such as an encoder, and it is possible to prevent a wasteful measurement operation from being performed.

  According to the invention described in item (10) above, when the sheet reaches the timing roller, the hold function for exciting the timing roller driving motor is not used, so that no hold power is required and the motor power consumption is reduced. The In addition, since the relative position of the transfer image and at least one of the paper is corrected based on the measured pop-out amount, the image can be transferred to the appropriate position on the paper.

  According to the invention described in the above item (11), when the paper reaches the timing roller, the hold function for exciting the timing roller driving motor is not used, and the transfer image is determined based on the measured pop-out amount. It is possible to cause the computer of the image forming apparatus to execute processing for correcting the relative position of at least one of the sheets with respect to the other.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a schematic configuration diagram of an example in which a brushless motor is used instead of a stepping motor in the image forming apparatus. 2 is a block diagram illustrating an electrical configuration of the image forming apparatus. FIG. FIG. 6 is an operation explanatory diagram for delaying the start timing of a motor when an encoder for measuring the amount of paper protruding from the nip portion of the timing roller is built in the timing roller driving motor. FIG. 6 is an operation explanatory diagram for delaying the start timing of the timing roller driving motor when the encoder is similarly built in the timing roller. (A) is a characteristic diagram of time and speed when the timing roller driving motor activation timing is delayed, and (B) is a time and speed characteristic diagram when the timing roller driving motor is activated at a low speed. It is. FIG. 6 is an operation explanatory diagram of a main part in the case where the light emission timing of laser light to the photosensitive member is delayed. 6 is a table showing a relationship between a paper type and a durability factor which are referred to when correcting a relative position between a transfer image and a paper. It is a graph which shows the relationship between the durable frequency of a timing roller, and the durable coefficient (alpha). 6 is a flowchart illustrating a correction process of a relative position between a transfer image and a sheet, which is performed by the image forming apparatus. It is a flowchart which shows another correction process of the relative position of a transfer image and a paper. It is a flowchart which shows another correction process of the relative position of a transfer image and a paper. It is a flowchart which shows another correction process of the relative position of a transfer image and a paper.

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

  FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to an embodiment of the present invention.

  In FIG. 1, the image forming apparatus includes a main body 10A and a paper feed option 10B. The main body 10 </ b> A includes a transfer unit 2, a fixing unit 3, a paper discharge unit 4, a part of a paper feed unit 5, and a paper transport unit 6 that constitute a part of the print unit 1.

  In addition to developing the electrostatic latent image formed on the photoreceptor 71 (FIG. 7) with toner according to the image data of the original image read by the scanner unit (not shown), the print unit 1 forms a toner image. The toner image on the photoreceptor 71 is primarily transferred to an endless intermediate transfer belt 13 that is stretched around a plurality of rollers 11 and 12.

  The transfer unit 2 performs secondary transfer of the toner image on the intermediate transfer belt 13 onto the paper M by a transfer roller 14 that is in rolling contact with the one roller 12.

  The fixing unit 3 includes a pair of rollers 15 and 16 each having at least one of a heating roller, and heats and fixes the toner image transferred to the paper M.

  The paper discharge unit 4 has, for example, a pair of paper discharge rollers 18 and 19 driven by a stepping motor 40, and discharges the paper M that has passed through the fixing unit 3 to a paper discharge tray (not shown). It is. The paper discharge rollers 18 and 19 function as a reversing roller for returning the paper M to a paper reversing conveyance unit 62 to be described later in order to reverse the printing surface of the paper M when printing on the back side of the paper. It is configured.

  Reference numeral 17 denotes a paper discharge sensor for detecting the fixed paper M.

  The paper feeding unit 5 includes a plurality of (for example, four stages) paper feeding cassettes 5A, 5B, 5C, and 5D that store paper M. The paper feeding cassettes 5A and 5B belong to the main body 10A side, The paper feed cassettes 5C and 5D are paper feed options 10B.

  In each of the paper feed cassettes 5A, 5B, 5C, and 5D, a pickup roller 21 that pulls out the paper M one by one, and a paper feed that feeds the single paper M drawn by the pickup roller 21 to the paper transport unit 6. And stepping motors 24 for driving the picking rollers 21 and one of the paper feeding and separating rollers 22 and 23.

  The paper transport unit 6 includes a main transport path 61 that transports the paper M fed from the paper feed unit 5 to the paper discharge unit 4 and a paper discharge / reverse roller when printing on the back surface of the paper M. And a paper reversing conveyance path 62 for reversing the printing surface of the paper M returned from 18 and 19 and conveying it to the transfer unit 2.

  In the main transport path 61, a pair of transport rollers 7A (7B, 7C), 8A (8B, 8B) for transporting in the vertical direction (upward direction) with respect to the paper M corresponding to the respective paper feed cassettes 5B (5C, 5D). 8C) is deployed.

  These transport rollers 7A (7B, 7C) and 8A (8B, 8C) are driven to rotate by stepping motors 9A (9B, 9C), respectively, and are fed by the respective feed rollers 21, 22. The paper M is transported along the transport path 61.

  In the sheet reversal conveyance path 62, a pair of double-sided conveyance rollers 62A, 63A (62B, 63B) (62C, 63C) are arranged, and these conveyance rollers 62A, 63A (62B, 63B) (62C, 63C). ) Are each driven to rotate by a stepping motor 64.

  In addition, a pair of timing rollers 31 and 32 are disposed in the main transport path 61 at a position near the upstream side of the transfer unit 2, and these timing rollers 31 and 32 are rotationally driven by a stepping motor 33. It is like that. In the vicinity of the upstream side of these timing rollers 31 and 32, a timing sensor 34 for detecting the conveyed paper M is disposed.

  When the paper M reaches the timing rollers 31 and 32, the drive motor 33 of the timing rollers 31 and 32 is in a drive stop state because the power supply is cut off. At the time of activation, the position of the sheet is corrected by shifting the activation timing according to the measured value of the amount of protrusion of the leading edge of the sheet M from the nip portion of the timing rollers 31 and 32, or the position of the sheet is decreased by slowing the activation speed. By correcting this, the paper M is properly positioned with respect to the transfer image.

  It should be noted that the stepping motor 24 in the paper feeding unit 5, the stepping motors 9A, 9B, and 9C in the transport path 61, the stepping motor 40 in the paper discharge unit 4, the stepping motor 33 for the timing roller, and the stepping motor in the paper reversing transport path 62 64 is not limited to this. For example, as shown in FIG. 2, a brushless motor (BLM) 240 in the paper feeding unit 5, brushless motors (BLM) 90 </ b> A, 90 </ b> B, 90 </ b> C in the conveyance path 61, a brushless motor 400 in the paper discharge unit 4, and a timing roller The brushless motor 330 can be changed to the brushless motor 64 of the paper reversing conveyance path 62, and a brush motor can also be adopted. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 3 is a block diagram showing the electrical configuration of the image forming apparatus.

  In FIG. 3, the image forming apparatus includes an operation panel 100, a controller board 200, and an engine control board 300.

  The operation panel 100 includes a panel control unit 101, a key unit 102 having various hard keys, and a display unit 103 made of an LCD or the like. The operations of the key unit 102 and the display unit 103 are controlled. Controlled by the unit 101.

  The controller board 200 includes a control unit 201 and a driver unit (driver unit IC) 202 for a laser (see FIG. 7) 203.

  The control unit 201 receives a control instruction from the control unit 101 of the operation panel 100 and sends an enable signal and an APC (automatic output control) signal to the driver unit 202.

  The driver unit 202 drives a laser 203, and the laser 203 emits a laser beam L (FIG. 7) for exposure to the surface of the photoreceptor 71. In addition, a PD signal is sent from the driver unit 202 to the control unit 201.

  The control unit 201 controls driving by sending an enable signal and a clock signal to the driving polygon motor (FIG. 7) 205 of the polygon mirror (FIG. 7) 204 that scans the laser light L. ing. Further, a lock signal is sent from the polygon motor 205 to the control unit 201.

  The engine control unit 300 includes a control unit 301 instructed by the control unit 201 on the controller board 200, a storage unit 302, and driver units 303, 304, and 305 controlled by the CPU of the control unit 301.

  The storage unit 302 includes, for example, a hard disk device (HDD), a semiconductor memory, and the like. In addition to storing various data, the storage unit 302 stores an operation map, and stores sheet correction information related to correction of a sheet protruding from the timing roller. It is means to do.

  The CPU of the control unit 301 sends an enable signal and a clock signal to the driver unit 303.

  The driver unit 303 drives motors (stepping motors and brushless motors) 24 and 240 in the sheet feeding unit 5.

  The control unit 301 is configured to send an enable signal and a clock signal to the driver unit 304.

  The driver unit 304 drives the transport motors (stepping motors and brushless motors) 9A, 90A, 9B, 90B, 9C, 90B and the like.

  The control unit 301 sends an enable signal and a clock signal to the driver unit 305.

  The driver unit 305 drives the timing roller driving motors (stepping motors and brushless motors) 33 and 330.

  The timing sensor 34 detects that the paper M has reached the timing rollers 31 and 32 and sends a timing signal to the control unit 301. An encoder 30 (shown in detail in FIGS. 4 and 5) 30 incorporated in the timing roller driving motor 33 (330) sends an encoder pulse signal to the control unit 301.

  Further, the temperature / humidity sensor 306 detects temperature / humidity and sends a temperature / humidity signal to the control unit 301. That is, when the relative position correction between the paper and the image is performed by the timing rollers 31 and 32, even if the paper other than the paper that does not require correction, for example, thick paper, if the humidity is a certain level or higher, the image by the timing rollers 31 and 32 is used. Position correction is not performed.

  In the image forming apparatus configured as described above, operation information on the operation panel 100 is transmitted from the control unit 101 to the control unit 201 of the controller board 200, and based on this, the control unit 201 of the controller board 200 controls the engine control board 300. Engine control information is transmitted to unit 301. And each load is controlled by CPU in the control part 301 based on the control information.

  The CPU in the control unit 301 changes the system speed in accordance with, for example, the user setting mode (for example, 165 mm / s for plain paper and 55 mm / s for cardboard).

  Further, the CPU in the control unit 301 transmits an enable signal and a clock signal corresponding to the driving speed to each motor driver unit 303 (304, 305), etc., so that the paper feed motor 24 (240), the transport motor 9A (90A), 9B (90B), 9C (90C), timing roller driving motor 33 (330), and the like are operated under desired conditions.

  Further, the CPU in the control unit 301 detects that the paper M has reached the timing rollers 31 and 32 when the timing sensor 34 is switched from OFF to ON, and after a certain time, the transport rollers 7A, 8A. Etc. is stopped. The pulse signal of the encoder 30 of the timing rollers 31 and 32 is monitored for a certain time after the stop, and the number of pulses is counted.

  Further, the CPU in the control unit 301 transfers the paper M to the transfer position by driving the motor 33 (330) while correcting and controlling the start timing of the timing roller driving motor 33 (330). The position of the image is adjusted to a predetermined position on the paper M, and at the time of writing the image, the polygon motor 205 is driven to rotate at a predetermined rotational speed, and the laser light L is emitted at a predetermined timing.

  FIG. 4 is an operation explanatory diagram for delaying the start timing of the motor 30 when the encoder 30 for measuring the amount of protrusion of the sheet M from the nip portion of the timing rollers 31 and 32 is incorporated in the timing roller driving motor 330. is there.

  In FIG. 4, when the sheet M is being conveyed by the conveying rollers 7A, 8A, etc., the power supply to the timing roller driving motor 330 is cut off, and therefore the timing rollers 31, 32 are not driven. Suspended without stopping.

  When performing image alignment at the time of transfer at the nip portion of the timing rollers 31 and 32 with respect to the sheet M, the timing signal is controlled by the engine control board 300 when the timing sensor 34 detects that the sheet M has passed. The control unit 301 is mounted in the motor (brushless motor in FIG. 4) 330 if the leading end of the sheet M protrudes from the nip portion of the timing rollers 31 and 32. The encoder 30 serving as the pop-out amount measuring unit is instructed to measure the pop-out amount D of the leading edge of the paper M.

  The encoder 30 measures the amount of protrusion D from the timing roller nip portion at the leading end of the sheet M when the sheet M protrudes as shown by the solid line (the broken line indicates no protrusion), and the amount of protrusion D is as follows. The number (amount) of pulses corresponding to is sent to the control unit 301. The control unit 301 calculates the rotation amount of the timing rollers 31 and 32 based on the number of pulses, and sets the delay time T (see FIG. 6) of the start timing of the motor 330 based on this, and accordingly the motor 330 The timing rollers 31 and 32 are activated by supplying power to the motor.

  For example, when the roller diameters of the timing rollers 31 and 32 are 20 mm and the rotation speed of the encoder 30 is 628 ppr, the sheet M of 0.1 mm per pulse from the encoder 30 is projected.

  In this example, since 10 pulses are output from the encoder 30, the amount D of the paper M protruding from the nip portion is 1 mm.

  In this way, the delay time T of the activation timing of the motor 330, that is, the timing rollers 31 and 32 is set by the control unit 301 based on the protrusion amount D (for example, 1 mm) from the nip portion at the leading edge of the paper M. become.

  In the example shown in FIG. 4, the brushless motor is used as the driving motor 330 for the timing rollers 31 and 32. However, as shown in FIG. Even in a configuration using a stepping motor, control is similarly performed. In FIG. 5, the encoder 30 is built in the timing rollers 31 and 32 (any one).

  Note that the means for measuring the amount of pop-out D of the paper M is not limited to the encoder 30 and may be a line sensor, for example.

  However, as shown in FIG. 5, when the encoder 30 is built in the timing rollers 31 and 32, it is possible to easily detect the pop-out amount D of the sheet M simply by changing the control method without changing the existing component configuration. Since this is possible, it is more advantageous than a configuration in which a line sensor is introduced.

  FIG. 6A is a characteristic diagram of time and speed when the activation timing of the drive motor 33 (330) of the timing rollers 31 and 32 is delayed.

  In FIG. 6A, the characteristics of the normal activation are indicated by solid lines, and the activation timing of the motor 330 (33) that drives the timing rollers 31 and 32 is delayed by T (time). The characteristics when corrected are indicated by dotted lines. The area of the hatched portion is the correction amount of the paper position when the start timing is corrected (in this example, 1 mm).

  In this case, by delaying the activation timing of the motor 330 (33) by time T, the sheet travel amount at the time of activation is reduced by a distance corresponding to the sheet pop-out amount D. That is, as a result of correcting the paper position by a distance corresponding to the paper pop-out amount D, the transferred image and the paper position can be properly matched.

  FIG. 6B is a characteristic diagram of time and speed when the rotational speed at the time of starting the timing rollers 31 and 32 by the motor 330 (33) is slowed down by position data corresponding to the paper pop-out amount D.

  In FIG. 6B, the characteristics of normal startup are indicated by a solid line, and the speed of the motor 330 (33) that drives the timing rollers 31 and 32 is reduced by a predetermined time to correct the paper position. The characteristics in this case are indicated by dotted lines. The area of the shaded area is the paper position correction amount (1 mm in this example).

  In this case, position data corresponding to the pop-out amount D of the paper M is subtracted before the motor 330 (33) is activated, and the activation is started. When controlling the paper position, the paper is driven at a slower speed than in normal driving, so the travel distance is reduced by an amount corresponding to the pop-out amount D (1 mm in this case) of the paper M. That is, as a result of correcting the paper position by a distance corresponding to the paper pop-out amount D, the transferred image and the paper position can be properly matched.

  FIG. 7 is an operation explanatory diagram in the case where the relative position between the sheet and the image is corrected by delaying the light emission timing of the laser beam L with respect to the photoconductor 71.

  In FIG. 7, a laser beam L emitted from a laser 203 and reflected by a polygon mirror 204 is irradiated in accordance with image data onto the surface of a photoreceptor 71 that is rotationally driven by a driving roller 70. As a result, the surface of the photoreceptor 71 is exposed to form an electrostatic latent image, and a toner image is formed on the electrostatic latent image on the surface of the photoreceptor 71 through a subsequent development process.

  When delaying the start-up time of the motor 330 that drives the timing rollers 31 and 32, the rotation of the polygon motor 205 is controlled by the control unit 201 of the controller board 200, so that the amount M of the paper M pops out. The light emission timing of the laser beam L is delayed so that the writing position on the surface of the photoreceptor 71 is shifted by a necessary amount P.

  For example, when the amount D of projection of the sheet M is, for example, 1 mm, the image forming position can be appropriately secured by delaying the light emission timing of the laser light L and moving the writing position forward by 1 mm.

  FIG. 8 is a table showing the relationship between the paper type and the basis weight coefficient, etc., which are used as a reference when correcting the alignment between the transferred image and the paper.

In FIG. 8, there are items of paper type, paper basis weight [g / m ² ], basis weight coefficient, and durability correction, and all the durability corrections are durability coefficients α (initial value is 1). . The paper types include thick paper (including coated paper) and plain paper.

In the case of thick paper, the basis weight coefficient is 1 in all cases where the paper basis weight [g / m ² ] is 91 to 300. In the case of plain paper, the basis weight coefficient is 0 in all cases where the paper basis weight [g / m ² ] is ˜90.

  FIG. 9 is a graph showing the relationship between the number of times of durability of the timing rollers 31 and 32 and the durability coefficient α.

  In FIG. 9, the endurance coefficient increases as the endurance count of the timing rollers 31 and 32 exceeds a certain value.

  As for the durability coefficient α, a durability coefficient α, which is a relationship between the number of times of durability of the timing rollers 31 and 32 and the slip amount, is calculated in advance through experiments or the like. Then, the following expression is used, and this is set as the actual front end position amount of the paper M.

Leading edge position of paper M = number of pulses of encoder 30 × 0.1 × basis weight coefficient × durability coefficient α
Here, since the weighing coefficient of plain paper is 0, in this embodiment, it is assumed that the paper protrudes from the timing roller only when the weighed paper has a weighing coefficient of 1.

  FIG. 10 is a flowchart showing an operation in a case where the start timing of the timing roller driving motor 33 (330) is delayed to correct the alignment between the transfer image and the paper. Note that the operations shown in the flowcharts in FIG. 10 and after are executed by the CPU of the control unit 301 operating according to an operation program recorded in a recording medium such as a ROM (not shown).

  In FIG. 10, in step S1, the sheet M fed from the sheet feeding unit 5 is being conveyed by the conveying rollers 7A, 8A, etc., but the timing roller driving motor 33 (330) is stopped. In FIG. 10, the timing roller driving motor is simply referred to as a timing motor.

  In step S <b> 2, when the leading edge of the sheet M being conveyed is detected by the timing sensor 34, the conveyance is stopped after a predetermined time has elapsed, and the pulse amount (number) of the encoder 30 is counted for a certain stop period.

  In step S3, it is determined whether or not the conveyance driving of the paper M has been completed. If the conveyance driving of the paper M has not been completed (NO in step S3), the process returns to step S2 to wait for the driving to be completed. If the conveyance driving of the paper M is completed (YES in step S3), the count value of the pulse amount (number) of the encoder 30 is determined in step S4.

  In step S5, it is determined whether or not the count value of the pulse amount (number) of the encoder 30 has increased from 0 (count value> 0). If the count value is not 0 (NO in step S5), in step S8, Then, the timing rollers 31 and 32 are activated without correction and the processing is terminated. If the count value> 0 (YES in step S5), the process proceeds to step S6.

  In step S6, the pop-out amount D of the sheet M is calculated from the count value (number of pulses). In step S7, the delay timing is determined from the pop-out amount D, and start-up is started.

  FIG. 11 is a flowchart showing an operation when correcting the alignment of the transfer image and the paper in consideration of the paper type, temperature, and humidity.

  In FIG. 11, in step S11, it is determined whether or not the paper is thick. If the paper is not thick (NO in step S11), the power of the encoder 30 is cut to reduce power in step S22, and in step S23. Then, the timing rollers 31 and 32 are started without performing the correction control, and then the process ends.

  If the paper is thick (YES in step S11), it is determined in step S12 whether or not the humidity is 70% or more. If the humidity is 70% or more (YES in step S12), the process proceeds to step S22 to reduce power consumption. Therefore, the power of the encoder 30 is cut. If the humidity is not 70% or more (NO in step S12), the process proceeds to step S13.

  In step S13, the sheet M fed from the sheet feeding unit 5 is being conveyed by the conveying rollers 7A, 8A, etc., but the timing roller driving motor 33 (330) is stopped. In step S <b> 14, when the leading edge of the sheet M being conveyed is detected by the timing sensor 34, the conveyance is stopped after a predetermined time has elapsed, and the pulse amount (number) of the encoder 30 for a certain stop period is counted.

  In step S15, it is determined whether or not the conveyance driving of the paper M has been completed. If the conveyance driving of the paper M has not been completed (NO in step S15), the process returns to step S14 to wait for the driving to be completed. When the conveyance driving of the sheet M is completed (YES in step S15), in step S16, the count value of the pulse amount (number) of the encoder 30 is determined.

  In step S17, it is determined whether the count value of the pulse amount (number) of the encoder 30 has increased from 0 (count value> 0). If the count value is not> 0 (NO in step S17), the process proceeds to step S23. Proceed, start timing rollers 31 and 32 without correction, and end. If the count value> 0 (YES in step S17), the process proceeds to step S18.

  In step S18, the pop-out amount D of the paper M is calculated from the count value (number of pulses). In step S19, the durability coefficient α is calculated from the number of roller durability times. In step S20, the durability coefficient α is also taken into consideration. After the pop-out amount D is corrected by the equation: pop-out distance of paper M = number of pulses of encoder 30 × 0.1 × basis weight coefficient × durability coefficient α, the delay timing is calculated from the corrected pop-out amount D in step S21. To start.

  FIG. 12 is a flowchart showing an operation in the case where the start speed of the timing roller driving motor 33 (330) is slowed to correct the alignment between the transferred image and the paper.

  In FIG. 12, in step S31, the sheet M fed from the sheet feeding unit 5 is being conveyed by the conveying rollers 7A, 8A, etc., but the timing roller driving motor 33 (330) is stopped. In step S <b> 32, when the leading edge of the sheet M being conveyed is detected by the timing sensor 34, the conveyance is stopped after a predetermined time has elapsed, and the pulse amount (number) of the encoder 30 is counted for a certain stop period.

  In step S33, it is determined whether or not the conveyance driving of the paper M has been completed. If the conveyance driving of the paper M has not been completed (NO in step S33), the process returns to step S32 to wait for the driving to be completed. When the conveyance driving of the sheet M is completed (YES in step S33), in step S34, the count value of the pulse amount (number) of the encoder 30 is determined.

  In step S35, it is determined whether or not the count value of the pulse amount (number) of the encoder 30 has increased from 0 (count value> 0). If the count value is not 0 (NO in step S35), in step S39. If the count value> 0 (YES in step S35), the process proceeds to step S36.

  In step S36, the pop-out amount D of the paper M is calculated from the count value (number of pulses). In step S37, the motor position correction value β is subtracted from the position data of the motor control unit 301 from the pop-out amount D of the paper M (initial). Position information = 0−motor position correction value β).

  In step S38, the timing motor 33 (330) is activated at a lower speed than the normal activation.

  FIG. 13 is a flowchart showing an operation when correcting the alignment of the transferred image and the paper by delaying the timing of the electrostatic latent image writing operation for image formation.

  In FIG. 13, in step S41, the sheet M fed from the sheet feeding section 5 is being conveyed by the conveying rollers 7A, 8A, etc., but the timing roller driving motor 33 (330) is stopped. In step S42, when the leading edge of the sheet M being conveyed is detected by the timing sensor 34, the conveyance is stopped after a certain period of time, and the pulse amount (number) of the encoder 30 is counted for a certain stop period.

  In step S43, it is determined whether or not the conveyance driving of the paper M has been completed. If the conveyance driving of the paper M has not been completed (NO in step S43), the process returns to step S42 to wait for the driving to be completed. If the conveyance driving of the sheet M is completed (YES in step S43), in step S44, the count value of the pulse amount (number) of the encoder 30 is determined.

  In step S45, it is determined whether or not the count value of the pulse amount (number) of the encoder 30 has increased from 0 (count value> 0). If the count value is not 0 (NO in step S45), step S49 is performed. Then, the timing rollers 31 and 32 are started without being corrected, and then finished. If the count value is greater than 0 (YES in step S45), the process proceeds to step S46.

  In step S46, the pop-out amount D of the paper M is calculated from the count value (number of pulses). In step S47, the delay timing is determined from the pop-out amount D of the paper M, and image writing is started.

  In step S48, after a predetermined time, the timing roller driving motor 33 (330) starts to start and then ends.

  As described above, in this embodiment, when the sheet is aligned with the image by the timing rollers 31 and 32, the hold function for exciting the timing roller driving motor is not used, and the power to the timing roller driving motor is used. Since the supply is cut off, no hold power is required and the power consumption of the motor is reduced. In addition, since the relative position between the sheet and the image is corrected based on the measured amount of protrusion from the nip portion of the leading end of the sheet, the image can be transferred to the appropriate position on the sheet as in the conventional case.

  In the above embodiment, the start timing of the timing roller driving motor 33 (330) is delayed, the start speed is decreased, and the write timing of the image data is delayed independently. Although the relative position is corrected, two or more of these may be combined, and it is only necessary to correct the relative position with respect to at least one of the transfer image and the sheet.

5 Feeder 7A (7B, 7C), 8A (8B, 8C) Conveying roller 30 Paper pop-out amount measuring means (encoder)
31, 32 Timing roller 33 (330) Timing roller drive motor 34 Timing sensor 301 Control unit 203 Laser for electrostatic latent image writing D Paper projection amount (distance)
M paper P writing timing shift amount

Claims (11)

A transport roller for transporting paper fed from the paper feed unit;
A timing roller provided on the upstream side of the transfer position of the image to the paper transported by the transport roller, temporarily stopping the paper and aligning the paper with the transfer image transferred to the paper;
A motor that rotationally drives the timing roller and that is powered off when the paper reaches the timing roller;
A pop-out amount measuring means for measuring a pop-out amount from the nip portion of the leading end of the paper stopped by the timing roller;
Correction means for correcting a relative position of at least one of the transfer image and the paper based on the pop-out amount measured by the pop-out amount measuring means;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the correction unit corrects the relative position by delaying a start timing of the timing roller by the motor in accordance with the pop-out amount measured by the pop-out amount measuring unit.   The correction unit corrects the relative position by slowing a rotation speed at the start of the timing roller by the motor for a predetermined period according to the pop-out amount measured by the pop-out amount measuring unit. The image forming apparatus described in 1.   4. The correction unit corrects the relative position by delaying a timing of a writing operation of an electrostatic latent image for image formation according to a pop-out amount measured by a pop-out amount measuring unit. The image forming apparatus according to any one of the above.   5. The image forming apparatus according to claim 1, wherein the pop-out amount measuring unit includes an encoder that detects a rotation speed of the motor and outputs a pulse. 6.   The image forming apparatus according to claim 1, wherein the correcting unit corrects the pop-out amount measured by the pop-out amount measuring unit according to a durable usage amount of the timing roller.   7. The paper that does not pop out depending on the type of paper is used as a correction-unnecessary sheet, and the correction unit does not correct the alignment of the transfer image and the sheet with respect to the correction-unnecessary sheet. The image forming apparatus described in 1.   The image forming apparatus according to claim 7, wherein the correction unit does not correct the alignment between the transfer image and the sheet even when the sheet is a sheet other than the correction-unnecessary sheet and the humidity condition is equal to or higher than a certain level. .   9. The image forming apparatus according to claim 7, wherein the pop-out amount measuring unit does not measure the pop-out amount with respect to the correction-unnecessary sheet when the type of the sheet is a correction-unnecessary sheet. A transport roller for transporting paper fed from the paper feed unit;
A timing roller provided on the upstream side of the transfer position of the image to the paper transported by the transport roller, temporarily stopping the paper and aligning the paper with the transfer image transferred to the paper;
A motor that rotationally drives the timing roller;
A method for correcting the alignment of a transfer image and paper in an image forming apparatus comprising:
Cutting off the power supply to the motor when the paper reaches the timing roller;
A pop-out amount measuring step for measuring a pop-out amount from the nip portion of the leading edge of the paper stopped by the timing roller;
A correction step of correcting a relative position of at least one of the transfer image and the paper based on the pop-out amount measured in the pop-out amount measuring step;
A method for correcting the alignment of a transferred image and a sheet in an image forming apparatus, comprising: A transport roller for transporting paper fed from the paper feed unit;
A timing roller provided on the upstream side of the transfer position of the image to the paper transported by the transport roller, temporarily stopping the paper and aligning the paper with the transfer image transferred to the paper;
A motor that rotationally drives the timing roller;
A transfer image and sheet alignment correction program to be executed by a computer of an image forming apparatus comprising:
Cutting off the power supply to the motor when the paper reaches the timing roller;
A pop-out amount measuring step for measuring a pop-out amount from the nip portion of the leading edge of the paper stopped by the timing roller;
A correction step of correcting a relative position of at least one of the transfer image and the paper based on the pop-out amount measured in the pop-out amount measuring step;
A program for correcting the alignment between a transfer image and a sheet, which is executed by the computer.

Images