JP5856912B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a motor control apparatus and an image forming apparatus that conveys a sheet to a printing unit using a driving force of a motor controlled by the apparatus.

  The image forming apparatus includes a motor and a load (for example, a photosensitive drum, a developing roller, a transport roller pair, etc.) to which the driving force of the motor is supplied, and the following two technologies have been proposed for controlling the motor. Yes.

  One is to detect the motor speed fluctuation based on the motor rotation speed detected by the encoder, and when the motor rotation abnormality is detected from the result, the motor speed control unit can control the speed that it can control. This is a technique for controlling the rotational speed of the motor to a lower level (for example, see Patent Document 1).

  The other one detects an error based on a comparison between a reference pulse signal indicating the target speed of the DC brushless motor and a rotation pulse signal which is a rotation signal indicating the rotation speed of the motor, and based on the error, a motor driver is detected. First adjustment means for adjusting a command signal to the circuit by PID calculation control processing, setting means for setting a gain used in PID calculation control processing, and a fluctuation range of the rotational speed of the DC brushless motor obtained from the rotation signal; This is a technique that includes a second adjustment unit that adjusts a set gain based on a target fluctuation range, and that determines an abnormality of a load connected to a DC brushless motor (see, for example, Patent Document 2).

JP 2010-74887 A JP 2009-183055 A

  When the motor and the load are connected by the driving force transmission part and can be switched between a transmission state in which the driving force is transmitted to the load and a cutoff state in which the transmission is cut off, the driving force transmission part is blocked. A time lag is inevitably generated from when the switching command for switching from the state to the transmission state is issued until the switch from the cutoff state to the transmission state.

  For example, the driving force transmission unit includes a clutch and a solenoid that drives the clutch. Depending on the individual difference of the clutch and solenoid, the value of the time lag differs for each driving force transmission unit, and even in the same driving force transmission unit, the value of the time lag changes due to aging of the clutch and solenoid.

A problem caused by this will be described with an image forming apparatus as an example. When the time lag value is different from a preset reference value, when the conveyance roller pair is rotated by the driving force of the motor to convey the sheet to the printing unit, the timing at which the printing unit prints an image on the sheet, and the printing unit The timing for supplying paper to the printer does not match. As a result, the image is printed with a shift to the upstream side or the downstream side in the paper transport direction with respect to the desired position of the paper. and to provide an image forming apparatus including the motor control equipment capable of measuring a time lag until it switched to the transmission state of the driving force.

  A motor control device according to one aspect of the present invention that achieves the above object is a driving force capable of switching between a motor and a transmission state that transmits the driving force of the motor to a load and a blocking state that blocks transmission. A transmission unit; a detection unit that detects a rotation speed of the motor; a motor control unit that rotates the motor at a predetermined first value; and the rotation speed is the first value. During rotation of the motor, the switching control unit that issues a switching command for switching the driving force transmission unit from the shut-off state to the transmission state, and the rotational speed detected by the detection unit are monitored, and the rotational speed is A monitor unit for determining whether or not a predetermined second value that is lower than the first value has been reached; and the rotation speed after the switching control unit issues the switching command. value The arrival time to reach, and a measuring unit for measuring a time lag from said been the switch command to be switched to the transmission state.

  In the motor control device according to one aspect of the present invention, the motor is rotated at a first value with a predetermined rotation speed. When the driving force transmission unit is switched from the cut-off state to the transmission state, the load on the motor increases, so that the rotational speed of the motor temporarily decreases to a value lower than the first value. According to the motor control device of one aspect of the present invention, after the switching command for switching to the transmission state of the driving force is issued, the rotation speed of the motor is set to a predetermined second value lower than the first value. When it arrives, it is considered that it has been switched to the transmission state, and the arrival time from when the switching command is issued until the rotation speed reaches the second value is measured. As a result, the time lag from when the switching command for switching to the driving force transmission state is issued until the switching to the driving force transmission state is measured.

  In the above configuration, the motor control unit feedback-controls the rotation speed to the first value based on the rotation speed detected by the detection unit.

  According to this configuration, since the detection unit is also used for arrival time measurement and feedback control, the cost of the motor control device can be reduced.

  An image forming apparatus according to another aspect of the present invention includes: the motor control device; a printing unit that prints an image on paper; a transport unit that functions as the load and transports the paper to the printing unit; The time is regarded as a time lag from when the switching command is issued until the transmission state is switched, and based on the arrival time, the printing unit prints the image on the paper at the first timing and the transport unit. Includes a timing control unit that performs control to match a second timing for supplying the paper to the printing unit.

  According to the image forming apparatus according to another aspect of the present invention, the arrival time from when the switching command is issued until the rotation speed reaches the second value is determined from when the switching command is issued until the rotation state is switched to the transmission state. It is considered a time lag. Then, based on the arrival time, the first timing at which the printing unit prints an image on a sheet and the second timing at which the transport unit supplies the sheet to the printing unit are matched. Accordingly, in each case, when the time lag value differs for each image forming apparatus due to individual differences in the driving force transmission unit, or when the time lag value changes due to aging of the driving force transmission unit in the same image forming apparatus, the first case. And the second timing can be matched.

  The said structure WHEREIN: The said timing control part controls the said 1st timing and the said 2nd timing to be matched by making the said printing part adjust the said 1st timing.

  This configuration is effective when it is difficult to adjust the second timing (for example, on the system of the image forming apparatus).

  The adjustment of the first timing at which the printing unit prints an image on paper is adjustment of the timing at which drawing of an electrostatic latent image is started on the photosensitive drum in the case of the toner method, and in the case of the ink jet method, the recording head is This is adjustment of the timing at which ink ejection starts on the paper.

  In the above-described configuration, the timing control unit changes the timing at which the switching control unit issues the switching command and adjusts the second timing to thereby change the first timing and the second timing. Control to match.

  This configuration is effective when it is difficult to adjust the first timing (for example, on the system of the image forming apparatus).

  According to the present invention, it is possible to measure a time lag from when a switching command for switching to a driving force transmission state is issued to when the driving force is switched to a transmission state.

1 is a diagram illustrating an outline of an internal structure of an image forming apparatus in which a motor control device according to an embodiment is incorporated. FIG. 2 is a block diagram illustrating a configuration of the image forming apparatus illustrated in FIG. 1. It is a block diagram which shows the structure of the motor control apparatus which concerns on this embodiment. It is a block diagram of an example of a rotary encoder. FIG. 6 is a perspective view for explaining the operation of the conveyance roller pair and the photosensitive drum (the conveyance roller pair is in a rotation stopped state). FIG. 6 is a perspective view for explaining the operation of the transport roller pair and the photosensitive drum (the transport roller pair is in a rotating state). It is a graph which shows the relationship between the rotational speed of a motor and time, and the graph which shows the signal (H signal) of a switching command. It is a flowchart explaining the operation | movement which the motor control apparatus which concerns on this embodiment measures arrival time. In the aspect which adjusts the 1st timing, it is a time chart which shows the start timing of a change command and drawing of an electrostatic latent image. FIG. 5 is a time chart showing a switching command and timing for starting drawing of an electrostatic latent image in a mode of adjusting a second timing. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an outline of the internal structure of an image forming apparatus 1 incorporating a motor control device according to an embodiment of the present invention. The image forming apparatus 1 can be applied to, for example, a digital multifunction machine having functions of a copy, a printer, a scanner, and a facsimile. The image forming apparatus 1 includes an apparatus main body 100, a document reading unit 200 disposed on the apparatus main body 100, a document feeding unit 300 disposed on the document reading unit 200, and an operation disposed on the upper front surface of the apparatus main body 100. Part 400 is provided.

  The document feeding unit 300 functions as an automatic document feeding device, and can feed a plurality of documents placed on the document placing unit 301 so that the document reading unit 200 can read them continuously.

  The document reading unit 200 includes a carriage 201 on which an exposure lamp and the like are mounted, a document table 203 made of a transparent member such as glass, a CCD (Charge Coupled Device) sensor (not shown), and a document reading slit 205. When reading a document placed on the document table 203, the document is read by the CCD sensor while moving the carriage 201 in the longitudinal direction of the document table 203. On the other hand, when reading a document fed from the document feeding unit 300, the carriage 201 is moved to a position facing the document reading slit 205, and the document fed from the document feeding unit 300 is scanned. Reading is performed by the CCD sensor through the reading slit 205. The CCD sensor outputs the read original as image data.

  The apparatus main body 100 includes a sheet storage unit 101, an image forming unit 103, and a fixing unit 105. The sheet storage unit 101 is disposed at the lowermost part of the apparatus main body 100 and includes a sheet tray 107 that can store a bundle of sheets. In the bundle of sheets stored in the sheet tray 107, the uppermost sheet is sent out toward the sheet conveyance path 111 by driving the pickup roller 109. In the paper transport path 111, a plurality of transport roller pairs 123 (the transport roller pairs 123a and 123b are shown in FIG. 1) are arranged at intervals. The conveyance roller pair 123 includes a drive roller and a passive roller, and the sheet passes between the rotating conveyance roller pair 123 and is conveyed along the sheet conveyance path 111 to the image forming unit 103 (an example of a printing unit).

  The image forming unit 103 forms a toner image on the conveyed paper. The image forming unit 103 includes a photosensitive drum 113, an exposure unit 115, a developing unit 117, and a transfer roller 119. The exposure unit 115 generates modulated light corresponding to image data (image data output from the document reading unit 200, image data transmitted from a personal computer, image data received by facsimile, etc.), and is uniformly charged. Irradiate to the peripheral surface of the photosensitive drum 113. As a result, an electrostatic latent image corresponding to the image data is formed on the peripheral surface of the photosensitive drum 113. In this state, a toner image corresponding to image data is formed on the peripheral surface by supplying toner from the developing unit 117 to the peripheral surface of the photosensitive drum 113. This toner image is transferred by the transfer roller 119 to the sheet conveyed from the sheet storage unit 101 described above.

  The sheet on which the toner image is transferred is sent to the fixing unit 105. In the fixing unit 105, heat and pressure are applied to the toner image and the paper, and the toner image is fixed on the paper. The paper is discharged to the stack tray 121 or the paper discharge tray 123.

  The operation unit 400 includes an operation key unit 401 and a display unit 403. The display unit 403 has a touch panel function, and displays a screen including soft keys. The user operates the soft keys while viewing the screen to make settings necessary for executing functions such as copying.

  The operation key unit 401 is provided with operation keys including hard keys. Specifically, a start key 405, a numeric key 407, a stop key 409, a reset key 411, a function switching key 413 for switching between a copy, a printer, a scanner, and a facsimile are provided.

  A start key 405 is a key for starting operations such as copying and facsimile transmission. A numeric keypad 407 is a key for inputting numbers such as the number of copies and a facsimile number. A stop key 409 is a key for stopping a copying operation or the like halfway. A reset key 411 is a key for returning the set contents to the initial setting state.

  The function switching key 413 includes a copy key, a transmission key, and the like, and is a key for switching between a copy function and a transmission function. When the copy key is operated, an initial copy screen is displayed on the display unit 403. When the transmission key is operated, an initial screen for facsimile transmission and mail transmission is displayed on the display unit 403.

  FIG. 2 is a block diagram showing a configuration of the image forming apparatus 1 shown in FIG. The image forming apparatus 1 has a configuration in which an apparatus main body 100, a document reading unit 200, a document feeding unit 300, an operation unit 400, a control unit 500, and a communication unit 600 are connected to each other by a bus. Since the apparatus main body 100, the document reading unit 200, the document feeding unit 300, and the operation unit 400 have already been described, description thereof is omitted.

  The control unit 500 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an image memory, and the like. The CPU executes control necessary for operating the image forming apparatus 1 on the above-described components of the image forming apparatus 1 such as the apparatus main body 100. The ROM stores software necessary for controlling the operation of the image forming apparatus 1. The RAM is used for temporary storage of data generated during execution of software, storage of application software, and the like. The image memory temporarily stores image data (image data output from the document reading unit 200, image data transmitted from a personal computer, image data received by facsimile, etc.).

  The communication unit 600 includes a facsimile communication unit 601 and a network I / F unit 603. The facsimile communication unit 601 includes an NCU (Network Control Unit) that controls connection of a telephone line with a destination facsimile, and a modulation / demodulation circuit that modulates / demodulates a signal for facsimile communication. The facsimile communication unit 601 is connected to the telephone line 605.

  A network I / F unit 603 is connected to a LAN (Local Area Network) 607. A network I / F unit 603 is a communication interface circuit for executing communication with a terminal device such as a personal computer connected to the LAN 607.

  FIG. 3 is a block diagram illustrating a configuration of the motor control device 3 according to the present embodiment. The motor control device 3 includes a motor 5, a motor driver 7, a rotary encoder 9, a driving force transmission unit 11, and a control unit 500.

  The motor 5 is a DC motor. The motor 5 that can be applied to the motor control device 3 according to the present embodiment is not limited to a DC motor, and can be applied to, for example, an AC motor or a stepping motor.

  The motor driver 7 (an example of a motor control unit) is a drive circuit that controls the rotation speed of the motor 5 by a pulse width modulation method. Not only the pulse width modulation method but also other methods (for example, a pulse amplitude modulation method) can be applied. The motor driver 7 includes a feedback control unit 13. The feedback control unit 13 feedback-controls the rotational speed to a predetermined first value based on the rotational speed of the motor 5 detected by the rotary encoder 9 described below. Control of the rotation speed of the motor 5 is not limited to feedback control. Other types of control may be used as long as the motor 5 can be controlled to rotate at the first rotation speed.

  The rotary encoder 9 (an example of a detection unit) is used to detect the rotational speed of the motor 5 and includes a pulse plate 15 and a photo interrupter 17 as shown in FIG. A large number of slits are formed along the outer periphery of the pulse plate 15, and the pulse plate 15 is fixed to the rotating shaft 19 of the motor 5. The photo interrupter 17 is arranged so that the slit of the pulse plate 15 can pass between the light emitting unit 21 and the light receiving unit 23.

  The driving force transmission unit 11 has a function of transmitting the driving force of the motor 5 to the photosensitive drum 113, the developing roller 125, the transport roller pair 123, and the like. In FIG. 3, the driving force transmission unit 11 a that transmits the driving force to the photosensitive drum 113, the driving force transmission unit 11 b that transmits the driving force to the developing roller 125, and the driving force transmission unit 11 c that transmits the driving force to the conveyance roller pair 123. It is shown.

  The developing roller 125 is a roller that is provided in the developing unit 117 and supplies toner to the photosensitive drum 113.

  As described with reference to FIG. 1, the conveyance roller pair 123 functions as a conveyance unit that conveys a sheet to the image forming unit 103 (an example of a printing unit). The conveyance roller pair 123 includes a driving roller 127 and a passive roller 129. The driving force of the motor 5 is transmitted to the driving roller 127 via the driving force transmission part 11c. The passive roller 129 rotates passively with the rotation of the driving roller 127.

  The driving force transmission unit 11 includes, for example, a clutch and a solenoid. The clutch is driven by a solenoid, and connects or disconnects the rotating shaft 19 (FIG. 4) of the motor 5 and the rotating shafts of loads (photosensitive drum 113, developing roller 125, transport roller pair 123, etc.). In this way, the driving force transmission unit 11 can be switched between a transmission state in which the driving force of the motor 5 is transmitted to the load and a blocking state in which transmission is blocked.

  The control unit 500 includes a monitor unit 501, a switching control unit 503, a measurement unit 505, and a timing control unit 507 as functional blocks.

  The switching control unit 503 performs control to switch the driving force transmission unit 11 between the transmission state and the cutoff state described above. When the switching control unit 503 issues a switching command for switching from the shut-off state to the transmission state, the driving force transmission unit 11 to which the switching command is issued is switched from the blocking state to the transmission state. When the switching control unit 503 issues a switching command for switching from the transmission state to the cutoff state, the driving force transmission unit 11 to which the switching command is issued is switched from the transmission state to the cutoff state. In the following description, the switching command means a command for switching the driving force transmission unit 11 from the cut-off state to the transmission state while the motor 5 is rotating at the first rotation speed.

  The monitor unit 501 monitors the rotational speed of the motor 5 detected by the rotary encoder 9, and after the switching command is issued, the rotational speed has reached a predetermined second value lower than the first value. It is determined whether or not.

  The measuring unit 505 determines the arrival time from when the switching control unit 503 issues a switching command until the rotational speed of the motor 5 decreases from the first value to reach the second value. It is measured as the time lag until switching to the transmission state.

  The timing control unit 507 regards the arrival time as a time lag from when the switching command is issued until the transmission state is switched, and based on the arrival time, the first timing at which the image forming unit 103 prints an image on a sheet. And the second timing at which the transport roller pair 123 supplies the sheet to the image forming unit 103 is controlled.

  5 and 6 are perspective views for explaining the operation of the transport roller pair 123a and the photosensitive drum 113. FIG. Referring to FIG. 5, since the driving force transmission unit 11a (FIG. 3) is in the transmission state, the photosensitive drum 113 is rotating. On the other hand, since the driving force transmission part 11c is in the cut-off state, the rotation of the driving roller 127 of the transport roller pair 123a is stopped.

  The image is transferred to the paper P1 by rotating the photoconductor drum 113 while the paper P1 is sandwiched between the photoconductor drum 113 and the transfer roller 119. Since the drive roller 127 stops rotating, the next paper P2 is stopped from being transported before the pair of transport rollers 123a.

  Referring to FIG. 6, when the transfer of the image onto paper P <b> 1 is completed, the driving force transmission unit 11 c is switched to the transmission state, whereby the driving roller 127 rotates and the next paper P <b> 2 is sent to the photosensitive drum 113. It is done.

  The switching control unit 503 shown in FIG. 3 instructs each driving force transmission unit 11 to switch from the cutoff state to the transmission state until the driving force transmission unit 11 is actually switched from the cutoff state to the transmission state. Cause a time lag.

  When the value of the time lag differs for each image forming apparatus 1 due to individual differences in the driving force transmission unit 11, or when the value of the time lag changes due to aging of the driving force transmission unit 11 in the same image forming apparatus 1, the value of the time lag Is different from a preset reference value.

  In the driving force transmission unit 11c of the transport roller pair 123, if the time lag value is different from the reference value, the first timing (the timing at which the image forming unit 103 prints an image on the paper) and the second timing (the transport roller pair). 123 does not match the timing at which the sheet is supplied to the image forming unit 103), and the image is printed with a deviation from the desired position on the sheet to the upstream side or the downstream side in the sheet conveyance direction.

  Therefore, in the present embodiment, the time lag is measured, and based on this, the first timing and the second timing are matched. First, the time lag measurement will be described. FIG. 7 is a graph showing the relationship between the rotational speed of the motor 5 and time, and a graph showing a switching command signal (H signal).

  The motor 5 is rotated at a first value with a predetermined rotation speed by feedback control. The switching control unit 503 issues a switching command, and the driving force transmission unit 11c is switched from a cut-off state (a state where transmission of the driving force of the motor 5 is cut off) to a transmission state (a state where the driving force of the motor 5 is transmitted). When this occurs, the load on the motor 5 increases. For this reason, the rotational speed of the motor 5 temporarily decreases to a value lower than the first value, but the rotational speed of the motor 5 is returned to the first value by the footback control.

  In the present embodiment, when the rotational speed of the motor 5 reaches a predetermined second value that is lower than the first value, the driving force transmission unit 11c is switched from the cutoff state to the transmission state. Therefore, the arrival time from when the switching command is issued until the rotation speed reaches the second value is measured. As a result, the time lag from when the switching command for switching to the driving force transmission state is issued until the switching to the driving force transmission state is measured.

  Further, according to the present embodiment, since the rotary encoder 9 is also used for arrival time measurement and feedback control, the cost of the motor control device 3 can be reduced.

  The operation in which the motor control device 3 according to the present embodiment measures the arrival time will be described mainly with reference to FIGS. FIG. 8 is a flowchart for explaining this operation.

  The control unit 500 determines whether the power of the image forming apparatus 1 is turned on (step S1). When the control unit 500 does not determine that the power of the image forming apparatus 1 is turned on (No in step S1), the process of step S1 is repeated.

  When the control unit 500 determines that the power of the image forming apparatus 1 is turned on (Yes in step S1), the motor driver 7 performs feedback control in which the rotation speed of the motor 5 becomes the first value (step S2).

  The monitor unit 501 monitors the rotational speed of the motor 5 and determines whether the rotational speed is controlled to the first value (step S3). When the monitor unit 501 does not determine that the rotation speed is controlled to the first value (No in step S3), the process of step S3 is repeated.

  When the monitor unit 501 determines that the rotation speed is controlled to the first value (Yes in step S3), the switching control unit 503 issues a switching command to the driving force transmission unit 11c (step S4).

  When the switching command is issued by the switching control unit 503, the measuring unit 505 starts measuring the arrival time (the time from when the switching command is issued until the rotation speed reaches the second value) (step S5).

  The monitor unit 501 monitors the rotational speed and determines whether the rotational speed has decreased and has reached the second value (step S6). When the monitor unit 501 does not determine that the rotation speed has reached the second value (No in step S6), the process in step S6 is repeated.

  When the monitor unit 501 determines that the rotation speed has reached the second value (Yes in step S6), the measuring unit 505 ends the arrival time measurement (step S7). As described above, the arrival time (time from step S4 to step S7), that is, the time lag is measured.

  Based on the arrival time, the timing control unit 507 performs the first timing (the timing at which the image forming unit 103 prints an image on the paper) or the second timing (the transport roller pair 123 causes the image forming unit 103 to feed the paper The first timing and the second timing are controlled by adjusting the (supply timing).

  A description will be given from the aspect of adjusting the first timing. FIG. 9 is a time chart showing the start timing of the switching command and the electrostatic latent image drawing in the aspect of adjusting the first timing.

  (A) shows the case where the arrival time is a predetermined reference value, (B) shows the case where the arrival time is shorter than the reference value, and (C) shows the case where the arrival time is longer than the reference value.

  The timing control unit 507 controls the image forming unit 103 to adjust the first timing to match the first timing and the second timing. The first timing adjustment is an adjustment of the timing at which the exposure unit 115 starts drawing an electrostatic latent image on the photosensitive drum 113. In the case of the ink jet system, this is adjustment of the timing at which the recording head starts to eject ink onto the paper.

  In the case of (B), the timing control unit 507 synchronizes the first timing and the second timing by advancing the timing at which the exposure unit 115 starts drawing the electrostatic latent image on the photosensitive drum 113.

  In the case of (C), the timing control unit 507 matches the first timing and the second timing by delaying the timing at which the exposure unit 115 starts drawing the electrostatic latent image on the photosensitive drum 113.

  According to the aspect of adjusting the first timing, it is effective when it is difficult to adjust the second timing (for example, on the system of the image forming apparatus).

  Next, an aspect of adjusting the second timing (timing when the conveyance roller pair 123 supplies the sheet to the image forming unit 103) will be described. FIG. 10 is a time chart showing the switching command and the start timing of drawing of the electrostatic latent image in the aspect of adjusting the second timing.

  (A) shows the case where the arrival time is a reference value, (B) shows the case where the arrival time is shorter than the reference value, and (C) shows the case where the arrival time is longer than the reference value.

  The timing control unit 507 performs control for adjusting the first timing and the second timing by changing the timing at which the switching control unit 503 issues a switching command and adjusting the second timing.

  In the case of (B), the timing control unit 507 adjusts the second timing by delaying the timing of issuing the switching command to the switching control unit 503, thereby matching the first timing and the second timing.

  In the case of (C), the timing control unit 507 matches the first timing with the second timing by adjusting the second timing by advancing the timing for issuing a switching command to the switching control unit 503.

  According to the aspect of adjusting the second timing, it is effective when it is difficult to adjust the first timing (for example, on the system of the image forming apparatus).

  As described above, according to the present embodiment, the arrival time from when the switching command is issued until the rotation speed reaches the second value is expressed as the time lag from when the switching command is issued until the rotation state is switched to the transmission state. I consider it. Then, based on the arrival time, the first timing at which the image forming unit 103 prints an image on a sheet and the second timing at which the conveyance roller pair 123 supplies the sheet to the image forming unit 103 are matched. Accordingly, when the value of the time lag differs for each image forming apparatus 1 due to the individual difference of the driving force transmission unit 11c, or when the value of the time lag changes due to aging of the driving force transmission unit 11c in the same image forming apparatus 1, In this case, the first timing and the second timing can be matched.

  Note that the timing control unit 507 adjusts the first timing and the second timing from the arrival time measured by the measurement unit 505 without providing a reference value for the arrival time. You may match the timing.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Motor control apparatus 7 Motor driver (an example of a motor control part)
9 Rotary encoder (example of detector)
103 Image forming unit (an example of a printing unit)
123 Transport roller pair (an example of transport section)

Claims (2)

A printing unit that prints an image on paper, a first transport roller pair, and a second transport roller pair disposed downstream of the first transport roller pair in the paper transport direction. An image forming apparatus comprising: a transport unit that transports the paper that has been transported in front of a pair of transport rollers to the printing unit; and a motor control device,
The motor controller is
A motor,
A driving force transmission unit capable of switching between a transmission state for transmitting the driving force of the motor to the transport unit and a blocking state for blocking transmission;
A detection unit for detecting the rotation speed of the motor;
A motor control unit that rotates the motor at a predetermined first value of the rotation speed;
A switching control unit that issues a switching command to switch the driving force transmission unit from the shut-off state to the transmission state while the motor is rotating at the first value;
A monitor that monitors the rotational speed detected by the detector and determines whether the rotational speed has reached a predetermined second value that is lower than the first value;
Measurement for measuring the arrival time from when the switching control unit issues the switching command until the rotational speed reaches the second value as a time lag from when the switching command is issued to when the switching state is switched to the transmission state comprises a part, the,
The image forming apparatus further includes:
The arrival time is regarded as a time lag from when the switching command is issued until the transmission state is switched, and based on the arrival time, the printing unit prints the image on the paper with the first timing and A timing control unit that performs control to match a second timing at which the conveyance unit supplies the paper to the printing unit;
The timing control unit controls the printing unit to adjust the first timing to adjust the first timing and the second timing,
The adjustment of the first timing is adjustment of timing for starting drawing an electrostatic latent image on the photosensitive drum in the case of the toner method, and in the case of the ink jet method, the recording head starts ejection of ink onto the paper. An image forming apparatus that adjusts the timing to perform. The image forming apparatus according to claim 1, wherein the motor control unit feedback-controls the rotation speed to the first value based on the rotation speed detected by the detection unit .

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