JP2020024290A - Image formation apparatus - Google Patents

Abstract

To solve such a problem that the supply of a horizontal synchronous signal is stopped and also the operation of a processing circuit for processing image data in synchronization with the horizontal synchronous signal is stopped, as a result, the image data remains in the processing circuit and an abnormal image is generated at the image formation after the jam restoration in a case where an optical scan device makes an emergency stop due to the occurrence of the jam of a recording medium in an image formation apparatus performing image formation using the horizontal synchronous signal being a light reception result of a BD sensor.SOLUTION: An image formation apparatus switches to the output of image data synchronized with a trigger signal from the output of the image data synchronized with a horizontal synchronous signal in accordance with the occurrence of the jam of a recording medium, and outputs the image data held in a processing circuit in synchronization with the trigger signal when the jam occurs.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an image forming apparatus that forms an image using a light beam.

  2. Description of the Related Art Conventionally, as an image forming apparatus using an electrophotographic method, an image forming apparatus that forms an electrostatic latent image on a photoconductor by scanning a light beam and forms a toner image by developing the electrostatic latent image is known. I have. Such an image forming apparatus is provided with an optical scanning device as a device for scanning a light beam. The optical scanning device includes a laser diode, a rotating polygon mirror, a driving motor for rotating the rotating polygon mirror, and a light receiving sensor (Beam Detector, hereinafter referred to as BD) for receiving a light beam deflected by the rotating polygon mirror. The main scanning synchronization signal is generated by the BD receiving the light beam.

  Patent Literature 1 discloses an image forming apparatus that generates a pseudo synchronization signal in which the main scanning synchronization signal is delayed according to the characteristics of the image forming apparatus. In the image forming apparatus disclosed in Patent Document 1, transfer of image data between processing circuits (integrated circuits) and processing of image data in the processing circuits are performed in synchronization with a pseudo synchronization signal.

JP 2005-326541 A

  In the conventional image forming apparatus, since the pseudo synchronization signal is generated in synchronization with the main scanning synchronization signal generated during image formation, the following problem may occur. For example, when a jam occurs on a recording medium during image formation, the CPU of the image forming apparatus stops the operation of the optical scanning device. When the operation of the optical scanning device is stopped, the main scanning synchronization signal is not generated, so that the pseudo synchronization signal generated in synchronization with the main scanning synchronization signal is not generated. When the generation of the pseudo synchronizing signal is stopped, if the processing and output of the image data for one page are not completed in the processing circuit as shown in FIG. 10, a part of the image data for one page remains in the processing circuit. Would. Then, when the jam is recovered, the image forming apparatus forms an image based on the image data remaining in the processing circuit, so that there is a possibility that a defect occurs in the output image.

  In order to solve the above problems, an image forming apparatus according to the present invention is an image forming apparatus that forms an image on a recording medium, comprising: a photosensitive member; a light source that emits a light beam when a current is supplied; A light source driver for supplying a current to the light source in accordance with a signal; a deflecting device for deflecting the light beam so that the light beam scans the photoconductor; and receiving the light beam deflected by the deflecting device A first processing circuit including a light receiving sensor, for generating a main scanning synchronization signal in response to the light receiving sensor receiving the light beam, a first processing circuit for performing a process of adjusting density to image data, The image data processed by the processing circuit is input from the first processing circuit in synchronization with the main scanning synchronization signal, and the input image data is converted into binary data. A processing circuit that outputs the driving signal to the light source driving unit, the second processing circuit generating a trigger signal different from the main scanning synchronization signal, and controls operations of the light source driving unit and the motor driving unit. Control means, wherein the control means controls the light source driving unit so that a driving current corresponding to the driving signal is not supplied to the light source in response to occurrence of a recording medium jam. The second processing circuit switches from output of image data synchronized with the main scanning synchronization signal to output of image data synchronized with the trigger signal in response to occurrence of a jam in the recording medium. And outputting the image data remaining in the second processing circuit in synchronization with the trigger signal.

  According to the present invention, when a recording medium jam occurs, the output of the image data from the processing circuit is switched from the output synchronized with the main scanning synchronization signal to the output synchronized with the trigger signal, so that the image remaining in the processing circuit is changed. Data can be output.

Sectional view schematically showing the schematic configuration of the image forming apparatus Block diagram showing the configuration of the control unit and laser scanner unit Block diagram showing the configuration of the image processing unit 4 is a flowchart illustrating the operation of the CPU according to the first embodiment. 5 is a flowchart illustrating the operation of the image processing unit after the image forming operation is stopped according to the first embodiment. Timing chart showing the operation of the control unit and the laser scanner unit according to the first embodiment. 9 is a flowchart illustrating the operation of the CPU according to the second embodiment. 11 is a flowchart illustrating the operation of the CPU according to the third embodiment. 11 is a flowchart illustrating the operation of the image processing unit after the image forming operation is stopped according to the third embodiment. Diagram showing issues that occur during an emergency stop when a jam occurs

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(Configuration of Image Forming Apparatus)
FIG. 1 is a sectional view showing the configuration of the image forming apparatus A. As shown in FIG. 1, the image forming apparatus A includes an image forming unit 10, a sheet feeding unit 20 that supplies a sheet to the image forming unit 10, an intermediate transfer unit 30 that transfers a toner image to a sheet, and a toner image And a fixing unit 40 for fixing the image.

  The image forming unit 10 includes charging wires (12Y, 12M, 12C, 12K), a laser scanner unit 13, developing units (14Y, 14M, 14C, 14K) around photosensitive drums (11Y, 11M, 11C, 11K). A drum cleaning blade (15Y, 15M, 15C, 15K) is provided. Here, the suffixes Y, M, C, and K of the reference numerals are the colors of the toners to be used, and indicate that they are yellow, magenta, cyan, and black, respectively. In the following description, suffixes Y, M, C, and K are omitted when it is not necessary to distinguish the colors of the toner.

  When the CPU 101 receives an instruction to start a printing operation from the controller 103 shown in FIG. 3, the sheet S stored in the sheet stacking unit 21a or 21b is sent to the intermediate transfer unit 30 by the feed roller 22a or 22b. At this time, the image forming unit 10 charges the surface of the photosensitive drum 11 that is in contact with the charging wire 12 by applying a charging bias to the charging wire 12. Then, the laser scanner unit 13 emits a laser beam and irradiates the photosensitive drum 11 with the laser beam. As a result, the potential of the photosensitive drum 11 partially decreases, and an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive drum 11.

  Thereafter, the developing device 14 applies a developing bias to the developing sleeve, thereby causing toner to adhere to the electrostatic latent image formed on the surface of the photosensitive drum 11 from the developing sleeve to form a toner image.

  The primary transfer charger 35 primarily transfers the toner image on the photosensitive drum 11 onto the intermediate transfer belt 31. The toner remaining on the photosensitive drum 11 without being transferred to the intermediate transfer belt 31 is removed by the drum cleaning blade 15. The toner image transferred to the intermediate transfer belt 31 is sent to the transfer nip Te, and the toner image is transferred to the sheet S.

  Thereafter, the sheet S to which the toner image has been transferred is conveyed to the fixing device 40, and is heated and pressed at a fixing nip portion formed between the heating unit 41a and the pressing unit 41b of the fixing device 40, and the toner image is formed. The image is fixed on the sheet S. Thereafter, the sheet S is discharged to the discharge unit 50 through the discharge conveyance path.

(Configuration of image processing unit)
Next, the configuration of the image processing unit will be described with reference to the block diagrams of FIGS. FIG. 3 shows the relationship between the control unit 100, the laser scanner unit 13, and the controller 103. The control unit 100 includes a CPU 101 as a control unit that performs basic control of the image forming apparatus A, and an image processing unit 102 that performs a correction process on image data transmitted from a controller 103 as a first processing circuit. . The image processing unit 102 is an ASIC that is a second processing circuit. The controller 103 performs screen processing, density adjustment processing (γ correction), magnification correction in the sub-scanning direction that is the rotation direction of the moving drum, color conversion processing, and the like on image data input from a reading device or an external information device. I do. The controller 103 performs processing relating to multi-valued image data indicating a density gradation.

  The laser scanner unit 13 includes a laser diode 131 serving as a light source for emitting a laser beam (light beam), a polygon mirror 134 (rotating polygon mirror) for horizontally scanning the laser beam, a polygon motor 133 for driving the polygon mirror 134, and a laser beam. A BD sensor 132 as a light receiving sensor for receiving light, a laser driver 104 as a light source driving unit for controlling a laser, and a polygon motor driving ASIC 105 as a motor driving unit for driving a polygon motor. The laser driver 104 outputs a drive current according to a drive signal (PWM signal), and the laser diode 131 emits light when the drive current is supplied. The CPU 101, the image processing unit 102, the controller 103, the laser driver 104, and the polygon motor drive ASIC 105 each perform serial communication and transmit and receive information.

  FIG. 4 is a block diagram illustrating a configuration of the image processing unit 102. Various processes required for image formation are performed in the image processing unit 102. For example, the image processing unit 102 includes a horizontal synchronization signal control unit 106 and a vertical synchronization signal control unit 109. The horizontal synchronizing signal control unit 106 generates a horizontal synchronizing signal (raw BD signal / main scanning synchronizing signal) according to the light receiving signal from the BD sensor 132, and the vertical synchronizing signal control unit 109 is arranged in the transport path of the recording medium. A vertical synchronizing signal (sub-scanning synchronizing signal) is generated based on the output of the detected sensor detecting the conveyance of the recording medium. The image processing unit 102 includes an image frame generation unit 110 and a magnification correction unit 111. The image frame generation unit 110 determines the image output position for the image data sent from the controller 103, and the magnification correction unit 111 corrects the image data to correct the magnification of the output image in the main scanning direction. The image processing unit 102 includes an internal register 112. The register 112 stores control data for performing data processing (correction processing) performed by the image processing unit 102. The setting of control data in the register 112 is performed by the CPU 101 in response to the activation of the image forming apparatus A. When the apparatus is emergency-stopped due to the occurrence of a jam, the entire image processing unit 102 may be reset to sell the image data remaining inside the image processing unit 102. However, since the CPU 101 has to re-set the control data in the register 112 before resuming the image formation after the recovery from the jam, there is a problem that it takes time until the image formation starts and the user waits.

  The horizontal synchronizing signal control unit 106 generates a pseudo BD signal (trigger signal) using a counter inside the image processing unit 102, and synchronizes the operation of the image processing unit 102 with the raw BD signal. And a horizontal synchronization control switching unit 108 that performs switching between control in synchronization with the pseudo BD signal and control in synchronization with the pseudo BD signal. A raw BD signal is input to the polygon motor drive ASIC 105. The polygon motor drive ASIC 105 controls the rotation speed of the polygon motor 134 based on the cycle of the raw BD signal.

(Example 1)
A series of operations of the CPU 101 according to the present embodiment will be described with reference to the flowchart in FIG. The operation of the image processing unit 102, the controller 103, the laser driver 104, and the polygon motor drive ASIC 105 related to the operation of the CPU 101 will be described with reference to the timing chart of FIG.

  When the image data for one page is buffered in the image register 113, the controller 103 instructs the CPU 101 to start a printing operation. In response to this, the CPU 101 sets the register 112 in the image processing unit 102 to operate under the raw BD control (S201).

  Next, the CPU 101 issues a polygon motor ON instruction to the polygon motor drive ASIC 105 (S202). Upon receiving the polygon motor ON instruction, the polygon motor drive ASIC 105 outputs a motor control signal (acceleration signal, deceleration signal) to rotate the polygon motor 133 (T101). When the rotation speed of the polygon motor 133 reaches a certain speed, a laser is emitted from the laser diode 131, and a raw BD signal is detected by the BD sensor 132. The laser driver 104 notifies the detected raw BD signal to the polygon motor drive ASIC 105 and the image processing unit 102 (T102).

  The polygon motor drive ASIC 105 controls the polygon motor control signals (acceleration signal, deceleration signal) based on the input timing of the raw BD signal, and controls the rotation speed of the polygon motor 133. The raw BD signal detected by the BD sensor 132 is notified to the image processing unit 102 (T102). The image processing unit 102 performs synchronization based on the raw BD signal, and the horizontal synchronization signal control unit 106 A synchronization signal is generated (T103).

  When the rotation speed of the polygon motor 133 becomes constant, the image forming apparatus A starts an image forming operation in accordance with the conveyance of the sheet S (S203). When the sheet S reaches the registration rollers 25a and 25b, the CPU 101 notifies the image processing unit 102 of a PTOP signal. Upon receiving the PTOP signal, the image processing unit 102 generates a vertical synchronization signal in the vertical synchronization signal control unit 109, and notifies the controller 103 of the vertical synchronization signal (T104).

  The controller 103 starts notifying the image processing unit 102 of the image data starting from the reception of the vertical synchronization signal, and notifies the image data line by line in synchronization with the horizontal synchronization signal (T105). The image processing unit 102 performs various corrections on the received image data, and converts the corrected multi-valued image data into a bit pattern including a plurality of binary bit data (binary data) using a predetermined lookup table. Convert. The corrected image data is output to the laser driver 104 as a drive signal (PWM signal) (T106). By repeating the drive signal, the laser driver 104 irradiates a laser beam from a position determined for each line to form a latent image.

  The CPU 101 monitors whether an emergency stop has occurred during image formation (S204), and if no emergency stop has occurred (NO in S204), ends the printing operation normally (S205).

  If a recording medium jam occurs during image formation (S204: YES), the image forming operation of the image forming apparatus A is stopped (S206). At this time, the laser diode 131 and the polygon motor 133 are also forcibly stopped. The stop at this time means that the laser diode 131 is not activated and the polygon motor 133 is not rotated.

  Next, the CPU 101 sets the register 112 in the image processing unit 102 to operate under the pseudo BD control (S207), and finally notifies the controller 103 that the printing operation has abnormally ended (S208).

  The operation of the image processing unit 102 after the image forming apparatus A stops operating will be described with reference to the flowchart of FIG. Upon receiving the notification of the pseudo BD control ON from the CPU 101 in S207, the image processing unit 102 synchronizes the operation of the image processing unit 102 with the pseudo BD signal from the control synchronized with the raw BD signal by the horizontal synchronization control switching unit 108. The switching is performed so as to perform control (S301).

  Further, the image processing unit 102 starts generating a pseudo BD signal using the pseudo horizontal synchronization signal generation unit 107 (S302). The pseudo BD signal is a signal serving as a reference for image writing timing, like the raw BD signal, and the image processing unit 102 performs synchronization based on the pseudo BD signal and can continue internal control. Therefore, the image processing unit 102 outputs the image signal line by line in synchronization with the pseudo BD signal (S303).

  The image processing unit 102 repeats the generation of the pseudo BD signal (S302) and the output of the image signal (S303) until the output of the image signal for one page is completed (NO in S304). Upon completion, the flow ends (YES in S304).

  As described above, according to the image forming apparatus of the first embodiment, even when the operation of the image forming apparatus A stops and the supply of the raw BD signal to the image processing unit 102 stops, the control is switched to the pseudo BD control. By performing control in synchronization with the pseudo BD signal, the operation of the image processing unit 102 can be continued.

  As a result, the image signal for one page can be completely output, and since there is no unnecessary image signal remaining in the image processing unit 102 at the start of the next print operation, an image in which the intermediate image of the previous job is output at the time of the next job. Failure can be prevented.

(Example 2)
In the first embodiment, when an emergency stop occurs during image formation, the control of the image processing unit 102 is always switched from the raw BD control to the pseudo BD control. It is not necessary to switch the control of the processing unit 102 from the raw BD control to the pseudo BD control and continue the operation of the image processing unit 102.

  In other words, when an emergency stop occurs during operations other than the electrostatic latent image operation such as the pre-rotation, the sheet interval, and the post-rotation operation, it is not always necessary to switch the control of the image processing unit 102 from the raw BD control to the pseudo BD control. The operation of the CPU 101 in this case will be described with reference to the flowchart of FIG. Since the flow from S211 to S216 is the same as the operation from S201 to S206 shown in the first embodiment, the description is omitted.

  When an emergency stop occurs and the operation of the image forming apparatus A is stopped, the CPU 101 determines whether an electrostatic latent image is being formed (S217). If the electrostatic latent image is not being formed (NO in S217), the controller 103 is notified of the abnormal end of the printing operation (S218). If an electrostatic latent image is being formed (S217: YES), the register 112 in the image processing unit 102 is set to operate under the pseudo BD control (S219). As a result, the image processing unit 102 switches from the raw BD control to the pseudo BD control, and outputs an image signal for one page (FIG. 6). Thereafter, the CPU 101 notifies the controller 103 that the printing operation has ended abnormally (S218), and the flow ends.

  As described above, according to the image forming apparatus of the second embodiment, when an emergency stop occurs during the pre-rotation, the sheet interval, or the post-rotation operation, the image processing unit 102 stops the operation with the raw BD control, Only when an emergency stop occurs during the formation of the electrostatic latent image, it is possible to switch to the pseudo BD control, and the operation time of the image processing unit 102 can be reduced.

(Example 3)
In the first and second embodiments, the example in which the image signal in the image processing unit 102 is output for one page at the time of emergency stop has been described. In the third embodiment, a case will be described with reference to the flowchart of FIG. 9 in which only an image signal remaining in the image processing unit 102 when an emergency stop occurs is output.

  Steps S221 to S228 are the same as steps S211 to S218 in the second embodiment, and a description thereof will be omitted. When the operation of the image forming apparatus A stops during the formation of the electrostatic latent image, the CPU 101 requests the controller 103 to stop the image signal (S229). As a result, the controller 103 stops notifying the image processing unit 102 of the image signal. Thereafter, the CPU 101 sets the register 112 in the image processing unit 102 to operate under the pseudo BD control (S230).

  The operation of the image processing unit 102 after the image forming apparatus A stops operating will be described with reference to the flowchart of FIG. Upon receiving the notification of the pseudo BD control ON from the CPU 101 in S230, the image processing unit 102 synchronizes the operation of the image processing unit 102 from the control synchronized with the raw BD signal to the pseudo BD signal by the horizontal synchronization control switching unit 108. The control is performed so as to perform control (S311). Further, the image processing unit 102 starts generating a pseudo BD signal using the pseudo horizontal synchronization signal generation unit 107 (S312), and outputs an image signal line by line in synchronization with the pseudo BD signal (S313). By S229, since the reception of the image signal from the controller 103 to the image processing unit 102 has already stopped at this time, the image processing unit 102 generates a pseudo BD signal while the image signal remains inside (S312). The output of the image signal (S313) is repeated (S314 YES), and the flow ends when the internal image signal disappears (S304 NO).

  As described above, according to the image forming apparatus of the third embodiment, when the operation of the image forming apparatus A stops during the formation of the electrostatic latent image and the supply of the raw BD signal to the image processing unit 102 stops, Since the notification of the image signal from the controller is stopped, and then the operation of the image processing unit 102 is switched to the pseudo BD control, the image processing unit 102 only outputs the image signal remaining inside at the time of the emergency stop. Get better. As a result, the output of the image signal can be completed in a shorter time.

  In the present embodiment, the control of the image processing unit 102 is switched from the raw BD control to the pseudo BD control according to the notification from the CUP 101. However, the presence or absence of the supply of the raw BD signal is determined inside the image processing unit 102, and the pseudo BD control The BD control may be switched.

13 laser scanner unit 100 control unit 101 CPU
102 Image processing unit 103 Controller 104 Laser driver 105 Polygon motor drive ASIC
106 horizontal synchronization signal control unit 107 pseudo horizontal synchronization signal generation unit 108 horizontal synchronization control switching unit 131 laser diode 132 BD sensor 133 polygon motor 134 polygon mirror

Claims (4)

An image forming apparatus that forms an image on a recording medium,
A photoreceptor,
A light source that emits a light beam when supplied with an electric current,
A light source driving unit that supplies current to the light source according to a driving signal,
A deflecting device that deflects the light beam so that the light beam scans the photoconductor,
A signal generation unit including a light receiving sensor that receives the light beam deflected by the deflecting device, and generating a horizontal synchronization signal in response to the light receiving sensor receiving the light beam,
A first processing circuit for performing processing for adjusting the density of the image data, and the image data processed in the first processing circuit are input from the first processing circuit in synchronization with the horizontal synchronization signal, and are input. A processing circuit that converts image data into binary data and outputs the binary data to the light source driving unit as the drive signal, and a second processing circuit that generates a trigger signal different from the horizontal synchronization signal;
The light source driving unit, and control means for controlling the operation of the motor driving unit,
The control unit controls the light source driving unit such that a driving current according to the driving signal is not supplied to the light source in response to occurrence of a recording medium jam,
The second processing circuit switches from output of image data synchronized with the horizontal synchronization signal to output of image data synchronized with the trigger signal in response to occurrence of a jam in the recording medium, and when the jam occurs. Outputting the image data remaining in the second processing circuit in synchronization with the trigger signal.   2. The image forming apparatus according to claim 1, wherein the second processing circuit generates the trigger signal in response to a recording medium jam. The second processing circuit is a processing circuit that performs a predetermined process on the image data processed by the first processing circuit, and converts the image data obtained by performing the predetermined process to binary data,
The image forming apparatus according to claim 1, wherein the second processing circuit has an internal register that stores control data for executing the predetermined processing.   The deflecting device includes a drive motor that rotates the rotary polygon mirror, and a motor drive unit that drives the drive motor. The motor drive unit rotates the drive motor based on a cycle of the horizontal synchronization signal. The image forming apparatus according to claim 1, wherein the speed is controlled.

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