JP2006065109A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus with which the deterioration in durability of a motor and noise are reduced without causing the reduction in throughput due to the rise time of the motor which rotates a polygon mirror. <P>SOLUTION: In the image forming apparatus in which laser light is modulated by a desired image signal outputted from an image signal generation means and the modulated laser light is deflected with the polygon mirror and a face to be scanned is scanned with the modulated light, thus an image is recorded, the control means for controlling the revolution of the motor which rotationally drives the polygon mirror for scanning with the laser beam stores the working rate of the image forming apparatus by time and the rotation speed of the motor is variably controlled on the basis of the working rate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus provided with a laser scanning device for scanning a laser beam.

  A typical image forming apparatus capable of performing printing at high speed includes a laser beam scanning apparatus.

  For example, in a laser beam printer, an electrostatic latent image is formed on a photoconductor by scanning a drum-shaped photoconductor with a laser beam, for example, and the electrostatic latent image is developed with toner. An output image is obtained by forming a visible toner image and transferring the toner image onto a sheet.

  The outline of the laser scanning device is such that a laser beam generated and adjusted by a laser diode unit is reflected by a polygon mirror and guided to a photosensitive member. As the polygon mirror rotates at high speed, the laser beam is scanned on the photosensitive member in the length direction (main scanning direction) of the photosensitive member. Since the polygon mirror is driven by a motor and rotates at a high speed, a large noise (wind noise) is generated. In addition, the life of the motor that drives the polygon mirror to rotate is also a problem.

Therefore, conventionally, a control means for reducing the noise of the motor by reducing the rotation speed of the polygon mirror below a predetermined rotation speed at the end of the recording operation other than the time of image recording or at the time of auto shut-off so as to prevent a reduction in motor life. A configuration of (Patent Document 1)
In addition, the rotation time of the polygon mirror drive motor is counted, and when this rotation time has not reached the motor life, the rotation is continued at the same rotation speed as at the time of recording after the recording operation is completed. Has proposed an image recording apparatus that immediately stops the rotation of the motor when recording is completed. (Patent Document 2)
Japanese Examined Patent Publication No. 4-49688 JP 2000-301765 A

    However, when the polygon mirror is rotated at a low speed except during image recording, it is possible to shorten the time required to reach the high rated rotational speed. However, in recent high-speed laser printers, There was a problem that the rise time became a problem and the throughput was lowered. Moreover, it was necessary to use an expensive motor in order to further shorten the rise time.

    Also, if an inexpensive motor is used and the motor is rotated at a high speed after the recording operation is completed until the motor life is near, and the motor is stopped after the recording operation is completed, the motor rotation Rotating time was extended even when recording was not performed, and the motor life and noise reduction due to motor rotation could not be satisfied sufficiently.

  An object of the present invention is to provide an image forming apparatus that can effectively change the rotational speed of a polygon motor and reduce the life and noise of the motor.

    The image forming apparatus according to claim 1 of the present invention modulates laser light with a desired image signal output from the image signal generating means, and deflects the modulated laser light with a polygon mirror to be scanned. In an image forming apparatus that records an image by scanning a surface, a control unit that controls rotation of a motor that rotationally drives a polygon mirror for scanning a laser beam stores an operation rate of the image forming apparatus according to time. And based on the said operation rate, the rotational speed of the said motor is variably controlled.

  According to this configuration, the rotational speed of the polygon mirror drive motor can be effectively changed from the operating rate of the image forming apparatus according to the time.

    The image forming apparatus according to claim 2 of the present invention is the image forming apparatus according to claim 1, wherein the image forming apparatus is at least two or more based on the operating rate in different time zones of the day. And the rotational speed of the motor at the time of non-image formation is variably controlled stepwise by each group.

  According to this configuration, the rotational speed of the motor at the time of non-image formation can be varied stepwise by a group corresponding to the operating rate, which is more effective.

  The image forming apparatus according to claim 3 of the present invention is the image forming apparatus according to claim 2, wherein the groups of the operating rate ranges are classified into the first operating rate in descending order of the operating rate. , The second operating rate and the third operating rate group of 3; in the first operating rate group, the rotational speed of the motor is the rated rotational speed, and in the second operating rate group is low speed The rotation speed is set, and the rotation is stopped in the third operating rate group.

  According to this configuration, since the rotation of the motor is stopped in the time zone with the lowest operating rate, the life and noise of the motor can be further reduced.

  Low-speed rotation that can maintain the polygon mirror in the rated rotation state when image formation operation is likely to be performed, and can move the motor to the rated rotation state in a short time when image formation operation is unlikely Therefore, the noise of the motor can be reduced and the lifetime can be prevented from being lowered without lowering the throughput in a laser printer or the like.

    Hereinafter, a first embodiment of a digital multi-function peripheral as an example of an image forming apparatus according to the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view mainly showing a mechanical configuration of a digital multi-function peripheral according to an embodiment of the present invention. The digital multi-function peripheral 1 includes a main body 1, first to third paper feed cassettes (111 to 113) disposed on the lower side of the main body 1, a bypass paper feed 114, a conveyance path 12, a registration roller pair 13, The image forming unit 14, the laser scanning device 141, the fixing unit 15, the paper discharge port 16, the in-cylinder paper discharge unit 17, the in-cylinder paper discharge tray 171, the automatic document feeder 18, the scanner unit 19, and the operation unit 20 are configured. .

  Sheets are stacked in the first to third sheet feeding cassettes (111 to 113), respectively. The in-body discharge unit includes an in-case discharge tray 171 and the like, and all the sheets discharged from the discharge outlet 16 are discharged to the discharge tray 171.

  Documents are stacked on the document conveying device 18. This document is conveyed one by one to the reading unit by the pickup roller 181, read by the scanner unit 19, and discharged to the document discharge unit 182.

    The operation for normal copying will be described with reference to FIG. When a document is set on the document conveying device 18 and the start button of the operation unit 20 is pressed, the document is conveyed one by one to the reading unit by the pickup roller 181, read by the scanner unit 19, and discharged to the document discharge unit 182. .

    The paper fed from either the first to third paper feed cassettes (111 to 113) or the paper feed bypass 114 passes through the conveyance path 12, and the latent image is written from the laser scanning device 141 to the photosensitive drum. In order to synchronize with the timing of the sheet and to align the leading edge of the sheet, the registration roller pair 13 is temporarily stopped, the toner image is transferred to the sheet by the image forming unit 14 at the timing, and then the heat roller and the pressure roller are fixed by the fixing unit 15. Then, the toner image is fixed by being sandwiched and heated, and then discharged from the discharge port 16 to the in-body discharge tray 171.

    A block diagram of the image forming apparatus according to the present embodiment will be described with reference to FIG. 2 (although it is common with the image forming apparatus according to the mechanical description above, a new reference numeral is given as an explanation of the block diagram). ). The digital multi-function peripheral 1 includes a scanner unit 232, an operation unit 241, a control unit 200, a printer unit 251, an image processing unit 261, an HDD (hard disk drive) 271, and a network IF unit 281.

    The scanner unit 232 includes an automatic document feeder 231 and includes an exposure lamp 191 and a CCD (charge coupled device) 192 shown in FIG. The scanner unit 233 reads an image from the original by irradiating the original conveyed by the automatic original conveying unit 231 one by one with the exposure lamp 191 and receiving the reflected light with the CCD 192, and obtains image data for the read image. The image is output to the image processing unit 261.

    The image processing unit 261 performs correction processing such as level correction and γ correction on the read image data as necessary, and performs processing such as enlargement or reduction processing on the image data as necessary.

    The printer unit includes a laser scanning unit 252, an image forming unit 253, a paper feeding / conveying unit 254, a fixing unit 255, and a discharged paper detecting unit 256. The image forming unit 253 includes a photosensitive drum, a developing device, a transfer roller, and the like, and develops the electrostatic latent image exposed by the light modulated by the image data by the laser scanning unit 252 with toner of the developing device. The laser scanning unit 252 will be described later.

    The developed toner image is transferred onto a transfer sheet conveyed one by one by a transfer roller, and fixed by a fixing unit 255. The fixed transfer paper is discharged to the in-body discharge unit 17 by the transport unit 254.

    The network IF unit 281 uses a network IF (10 / 100Base-TX) or the like to control transmission / reception of various data with a plurality of PCs such as PCs 291 and 292 connected via a LAN (Local Area Network). To do. The HDD 271 stores image data read by the scanner unit 233.

    The control unit 200 includes a CPU (Central Processing Unit) 221 that controls each unit of the apparatus, a ROM 222 (Read Only Memory) that stores program data and the like, a RAM (Random Access Memory) 223 that is used as a work area of the CPU 221, and various types A rewritable nonvolatile memory 226 such as an EEPROM (Electrically Erasable Programmable ROM) in which setting data is stored, an image data signal IMGS corrected and processed by the image processing unit 261, and a start signal generated prior to output of this IMGS SS, a polygon mirror drive motor mode control signal PMMS, a polygon mirror drive motor speed setting signal PMSS, an image signal generation means 224, and a timer calendar means 225 for performing time measurement processing of the current time and date.

  The operation unit 241 includes a display unit 243 constituted by a liquid crystal touch panel, a print button 2421, a ten key 2423 for setting the number of copies, a set button 2422 for setting items set by the display unit 243, the ten key 2423, and the like. Key input means 242 is included.

  Since the image forming apparatus of the present embodiment is the digital multi-function peripheral 1, when a print command is issued from the PC, the image signal and the number of prints sent from the line via the network IF unit 281 and the sort instruction The setting signal is developed into a bit image by a communication control means (not shown) by the communication control means (not shown), and this is sequentially sent to the printer unit 3 via the image signal generation means 224 to become an image as a signal of the laser scanning means 252.

    FIG. 3 is a block diagram showing a first embodiment for driving and controlling the rotation of the polygon mirror of the laser scanning means of the present invention. A motor 301 for rotating the polygon mirror 300 is a motor output from a motor drive circuit 302. It is driven by the control signal PMD. The motor drive circuit 302 is controlled to be stopped and rotated by a motor on / off signal PMSW input from the control means 303, and the rotation speed during rotation is controlled by a motor speed control signal PMV.

  The control unit 303 controls the motor 301 by generating a motor on / off signal PMSW and a speed control signal PMV based on various signals input from the image signal generation unit 224 that generates an image signal.

  In addition to the image signal IMGS, the control means 303 determines a start signal SS, a mode control signal PMMS for setting a mode for rotating the motor at a rated speed or a low speed, and the rotational speed of the motor at a low speed. The mode speed setting signal PMSS is input. When the PMSS signal is 0 V, the motor stops when the low-speed rotation mode is set. There is also a motor ready signal PMRDY that is output when the motor reaches the rated rotation.

  FIG. 4 is a graph showing changes in the operation rate in the time zone of one day. The horizontal axis represents the time zone, and the vertical axis represents the operating rate of the image forming apparatus. The operating rate here is, for example, the number of output images per unit time. The operation rate of the image forming apparatus in each time zone is stored in the EEPROM 226.

  In addition, for example, three groups are formed by this operation rate. Predetermined values K1 and K2 (K2> K1) are stored in advance in the ROM 222 as operating rate threshold values. If the operating rate in that time period is less than K1, the operating rate in that time range is K1 or higher. If the operating rate is less than 2, the operating rate is medium, and if the operating rate during that time is K2 or higher, the operating rate is high. For example, at 12 o'clock time when the workplace is lunch break, the number of image output is 0, and it becomes a low operating rate group.

  FIG. 5 is a timing chart showing various signals when an image corresponding to the image signal IMGS is recorded. FIG. 5A shows a high operation rate, FIG. 5B shows a medium operation rate, and FIG. Shows the change in control by each group with low availability.

  5A, the mode control signal PMMS is always HIGH, that is, the motor is controlled to the rated rotation mode, and when the start signal SS is input, the motor rotation speed is set to a high-speed rated rotation state. Since it is maintained, the image signal generation means 224 outputs the image signal IMGS as shown in FIG. Therefore, there is no problem that the rise time of the motor 301 becomes a problem and the throughput is lowered. When the image output is completed, the motor rotation speed is maintained at a high speed.

  In the control of the medium operation rate in FIG. 5B, the mode control signal PMMS is maintained in LOW, that is, the low speed mode, and is rotated at a low speed at a speed set by the mode speed setting signal PMSS.

  Thereafter, when an image output request is generated, the mode control signal PMMS is released from the low speed mode as shown in FIG. 5B, and the motor 301 rapidly increases the rotational speed toward the rated rotational state. Thereafter, when reaching the rated rotation, the control means 303 outputs a motor ready signal PMRDY (not shown), and the image signal generation means 224 outputs the image signal IMGS when the PMRDY signal is inputted. Therefore, when the start signal SS is input, the motor 301 can be promptly shifted to the rated rotation state. When the image output ends, the motor rotation speed shifts to a low speed.

  In the low operation rate control of FIG. 5C, the mode control signal PMMS is maintained in LOW, that is, the low speed mode, but the mode speed setting signal PMSS is set to 0 V as shown in FIG. 5C. Therefore, the motor is stopped.

  Thereafter, when an image output request is generated, the mode control signal PMMS is released from the low speed mode as shown in FIG. 5C, and the motor 301 rapidly increases the rotational speed toward the rated rotational state. Thereafter, when reaching the rated rotation, the control means 303 outputs a motor ready signal PMRDY (not shown), and the image signal generation means 224 outputs the image signal IMGS when the PMRDY signal is inputted. Therefore, when the start signal SS is input, the motor 301 can be promptly shifted to the rated rotation state. When the image output is finished, the motor rotation speed is stopped.

  In addition, although the example which calculates | requires an operation rate in the time slot | zone of a day was shown, the operation rate for every day of the week may be memorize | stored in each time slot | zone, and an operation rate may be calculated | required on each day of the week.

1 is a schematic side sectional view showing a mechanical configuration of a digital multi-function peripheral to which the present invention is applied. FIG. 2 is a block diagram mainly showing an example of the electrical configuration of the digital multifunction peripheral shown in FIG. 1. It is a block diagram by a 1st embodiment. It is a graph which shows the operation rate by 1st Embodiment. It is a timing chart by a 1st embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Digital compound machine 17 The inside of a cylinder is a paper discharge part. 18 Automatic document feeder 19 Scanner part 20 Operation part 141 Laser scanning device 224 Image signal production | generation means 225 Timer calendar means 226 EEPROM
241 Operation unit 242 Key input means 300 Polygon mirror 301 Motor 303 Control means

Claims (3)

    In an image forming apparatus for recording an image by modulating laser light with a desired image signal output from an image signal generating means, deflecting the modulated laser light with a polygon mirror, and scanning a surface to be scanned. The control means for controlling the rotation of the motor that rotationally drives the polygon mirror for scanning the beam stores the operation rate of the image forming apparatus according to the time, and variably controls the rotation speed of the motor based on the operation rate An image forming apparatus.   In different time zones of the day, classify into groups of at least two operating rate ranges based on the operating rates, and variably control the rotation speed of the motor at the time of non-image formation stepwise by each group. The image forming apparatus according to claim 1, wherein: The group of the operating rate range is a group of 3 of the first operating rate, the second operating rate, and the third operating rate in descending order of the operating rate. In the first operating rate group, the motor The image according to claim 2, wherein the rotation speed is a rated rotation speed, the rotation speed is low in the second operating rate group, and the rotation is stopped in the third operating rate group. Forming equipment.

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