JP2009297917A - Exposure control unit and its processing method, image forming apparatus, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable the prolongation of the life of a motor for photosensitive drum driving and a laser diode by not making the photosensitive drum and the laser diode actuate vainly in an image forming apparatus. <P>SOLUTION: A rotation control is performed by a BD control during A first mode which needs a rotational accuracy of a polygon motor 304. The first mode includes a mode for forming a print image, a mode for forming a batch image and a mode for measuring a BD period. The rotation control of the polygon motor 304 is performed by a FG control during A second mode which does not need the rotational accuracy of the polygon motor 304. The second mode includes the modes such as the one when flying start. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exposure control apparatus that controls an exposure apparatus that irradiates a photosensitive member with a light beam, a processing method thereof, an image forming apparatus that includes the exposure apparatus and the exposure control apparatus, and a program for realizing the processing method. About.

  2. Description of the Related Art An electrophotographic apparatus having an exposure apparatus that exposes an image with a laser beam is conventionally known.

  The exposure apparatus includes a laser diode, a polygon scanner, a polygon motor, and the like. The laser diode is controlled to be turned on according to the image data, and the polygon scanner reflects the laser beam from the laser diode by a plurality of mirrors to irradiate the photosensitive drum and deflects it in the main scanning direction.

  The rotation control of the polygon motor is performed by controlling the cycle of the output (hereinafter referred to as FG signal) of the Hall element that detects the rotation angle (rotation position) of the rotor to a cycle proportional to the target rotation speed. There is a way to do. Further, the period of the output of the BD sensor (hereinafter referred to as BD signal) for detecting the irradiation position of the laser light and generating the scanning start position reference signal in the main scanning direction of the image is controlled to a period proportional to the target rotational speed. There is a method of performing rotation control by doing.

  In general, the method of performing rotation control by the output of the FG signal (hereinafter referred to as FG control) is not sufficient to stably rotate the motor because the accuracy of the output from the Hall element is not obtained. There's a problem. On the other hand, in the method of performing the rotation control by the BD signal (hereinafter referred to as BD control), the rotation speed of the motor can be controlled with high accuracy and the motor can be stably rotated. There is a problem like this. That is, since the BD sensor must be irradiated with laser light in order to obtain the BD signal, the laser diode must be turned on every time the BD signal is detected. Therefore, there is a problem that the life of the laser diode is shortened.

  In order to solve these problems, FG control is performed when the polygon motor is started, the polygon motor rotation speed reaches the target speed, and after the stable rotation state is reached, the laser diode emits light and the BD control state is reached. There is something to move to.

  However, when performing the BD control, the laser is caused to perform APC emission at an indefinite timing when the first BD signal is detected, so that the photosensitive drum is irradiated with the laser beam for a maximum of several lines. Even if several lines, the photosensitive drum layer may be damaged if the photosensitive drum is continuously irradiated with the amount of APC light emission every time the polygon motor is started.

As a workaround, as disclosed in Patent Document 1, the photosensitive drum is rotated before laser scanning to prevent at least the scanning of the photosensitive drum in a stopped state, thereby preventing unevenness of the surface layer of the photosensitive drum and the photosensitive layer. Drum life has been kept.
JP 2003-285468 A

  However, in the conventional method described above, BD control is performed even in a mode in which it is not necessary to control the rotational speed of the polygon motor with high accuracy. Examples of such a mode include a case where the speed is stabilized by FG control and the BD control is entered but no image data comes. For example, when the polygon motor is started upon receiving a print job, the print job printing operation is stopped before the image signal is output, or when the flying starts.

  Flying start is a function for quickly setting a print standby state by starting a polygon motor before an image signal is output. This function is used when, for example, the user operates a key provided on the operation unit, when the user sets a document on the document feeder, or when a print job is output from a network communication interface. Used.

  In the conventional method, in such a mode in which the polygon motor is rotated when image formation is not performed, BD control is performed even though it is not necessary to control the rotation speed of the polygon motor with high accuracy. For this reason, the photosensitive drum and the laser diode are unnecessarily driven, which is a factor that shortens the life of the photosensitive drum driving motor and the laser diode.

  SUMMARY OF THE INVENTION In view of the above-described conventional problems, an object of the present invention is to provide an exposure control apparatus, a processing method thereof, an image forming apparatus, and a program as described below. That is, the photosensitive drum and the laser diode are not driven unnecessarily, and the life of the photosensitive drum driving motor and the laser diode can be extended.

  In order to achieve the above object, an exposure control apparatus according to the present invention reflects a light emitting element that is controlled to light according to image data and a light beam output from the light emitting element by a plurality of mirrors and deflects it in the main scanning direction. In an exposure control apparatus that controls an exposure apparatus that irradiates a photosensitive member with a light beam reflected by the rotary polygon mirror, the rotary polygon mirror that rotates, and means for rotationally driving the rotary polygon mirror. In the case of the first mode in which it is necessary to control the rotational speed of the rotary polygon mirror with high accuracy, the light beam detection means for detecting the rotation position, the rotation position detection means for detecting the rotation position of the rotary polygon mirror, The rotation control of the rotary polygon mirror is performed based on the detection signal of the light beam detection means, and in the case of the second mode which is a mode other than the first mode, the rotation polygon detection mirror is controlled based on the detection signal of the rotation position detection means. rotation Characterized by comprising a means for performing rotation control of a surface mirror.

  According to another aspect of the present invention, there is provided an image forming apparatus comprising the above exposure control apparatus.

  The processing method of the exposure control apparatus of the present invention includes a light emitting element that is controlled to be turned on according to image data, and a rotation that reflects a light beam output from the light emitting element by a plurality of mirrors and deflects it in the main scanning direction A processing method of an exposure control apparatus, comprising: a polygon mirror; and a means for rotationally driving the rotary polygon mirror, and controlling an exposure apparatus that irradiates a photosensitive member with a light beam reflected by the rotary polygon mirror, In the case of the light beam detection step for detecting the light beam, the rotation position detection step for detecting the rotation position of the rotary polygon mirror, and the first mode in which the rotation speed of the rotary polygon mirror needs to be controlled with high accuracy The rotation control of the rotary polygon mirror is performed based on the detection result of the light beam detection step, and in the second mode which is a mode other than the first mode, the detection result of the rotation position detection step is Based on said times Characterized by a step of controlling the rotation of the polygon mirror.

  The program of the present invention includes a light emitting element that is controlled to be turned on according to image data, a rotating polygon mirror that reflects a light beam output from the light emitting element by a plurality of mirrors and deflects the light beam in a main scanning direction, Read by a computer for executing a processing method of an exposure control apparatus that controls an exposure apparatus that irradiates a photosensitive member with a light beam reflected by the rotary polygon mirror. A program capable of detecting the light beam, a rotational position detecting step for detecting a rotational position of the rotary polygon mirror, and a rotational speed of the rotary polygon mirror need to be controlled with high accuracy. In the case of a certain first mode, the rotation control of the rotary polygon mirror is performed based on the detection result of the light beam detection step, and the second mode is a mode other than the first mode. Is characterized in that a step of performing rotation control of the rotating polygon mirror based on a detection result of the rotational position detecting step when.

  According to the present invention, since the photoreceptor and the light emitting element are not driven unnecessarily, it is possible to extend the life of the photoreceptor driving motor and the light emitting element.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Functional Block of Image Forming Apparatus>
FIG. 1 is a functional block diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention.

  The image forming apparatus includes a main body control unit 200, a CCD sensor 201, an image processing unit 202, an image data selector 203, a laser unit 204, an image forming unit 205, and a reader unit 250.

  The main body control unit 200 performs drive control of a reader unit 250 that reads a document image, and an image forming unit 205 that performs image formation processing according to image data read by the reader unit 250. The main body control unit 200 includes a CPU 200a that executes a program, a RAM 200b that provides a work area for the CPU 200a, and a ROM 200c that stores a control program executed by the CPU 200a.

  The ROM 200c stores a control program for executing each operation mode (image formation mode, patch image formation mode, BD cycle measurement mode, BD cycle calculation mode) to be described later, and a control program for controlling the entire image forming apparatus. ing. For example, the ROM 200 c stores a control program for converting image data read from a document by the CCD sensor 201 into predetermined image data using the image processing unit 202. Also, a control program for switching the image data received by the image data selector 203 to be transmitted to any of the laser unit 204, the image data compression / decompression unit 207, the image memory 208, and the function control unit 209 is stored. ing.

  The ROM 200c also includes a control program for feeding a document using the document feeding device 180 controlled by the document feeding device control unit 216, and a predetermined mode set in the post-processing device control unit 217. The control program that executes is stored. Further, a control program for controlling the image forming apparatus to execute a program for performing predetermined processing on the image data is also stored. Further, the ROM 200c controls the image forming apparatus to execute an image forming mode and a patch image forming mode which will be described later with reference to FIG. 3, and a BD cycle measuring mode and a BD cycle calculating mode which will be described with reference to FIG. A control program is also stored.

  The CCD sensor 201 constitutes a signal processing part of a color image sensor unit provided in the reader unit 250. The CCD sensor 201 captures and photoelectrically converts light reflected from the document out of light emitted from the document illumination lamp, and outputs image data obtained by the photoelectric conversion. The image processing unit 202 performs predetermined image processing on the image data output from the CCD sensor 201. The predetermined image processing is processing according to the image processing mode set via the operation unit 219.

  The image data selector 203 includes an image processing unit 202, a laser unit 204, an image data compression / decompression unit 207, an image memory 208, a scan image change unit 213, and a print image conversion unit 214 via an image data bus. And connected to. The control information is received from the main body control unit 200, and the direction in which the image data flows is determined based on the received control information.

  The laser unit 204 is a unit that performs exposure with a laser beam on the photosensitive drum 111 provided in the image forming unit 205, and includes an exposure apparatus and a part of the exposure control apparatus related to the present invention (see FIG. 2). The image forming unit 205 has a function of transferring an image formed on the photosensitive drum by exposure with laser light onto a recording material (described later in FIG. 8).

  The image forming apparatus includes an inter-CPU communication interface (I / F) unit 206, an image data compression / decompression unit 207, an image memory 208, a function control unit 209, an inter-CPU communication I / F unit 210, and an HD (hard disk) control. Part 211 and HD212.

  The inter-CPU communication I / F unit 206 is an interface that transmits and receives control information between the main body control unit 200 and the function control unit 209. The image data compression / decompression unit 207 aims to save the image data occupation ratio in the HD 212 when the image data output from the image data selector 203 is stored in the HD 212 which is a large-capacity nonvolatile memory. The output image data is compressed. The image data compression / decompression unit 207 decompresses original image data before compression when transferring the compressed image data stored in the HD 212 to the image data selector 203.

  The image memory 208 is a memory that temporarily stores the image data sent from the image data selector 203. The image data stored in the image memory 208 is sent to the image data selector 203 as necessary. The image memory 208 is a volatile memory.

  The function control unit 209 communicates with the main body control unit 200 and sends the image data control information received from the main body control unit 200 to the scan image change unit 213 and the print image conversion unit 214. As the image data control information, the image data sent from the image data selector 203 should be sent to the scan image changing unit 213, and the image data sent from the print image converting unit 214 should be sent to the image data selector 203. Control information to be output is considered.

  The print image conversion unit 214 receives print image data from the network communication I / F unit 215, performs a predetermined conversion process on the received image data, and sends the converted image data to the image data selector 203. The function control unit 209 transmits control information input via the operation unit 219 and controlling the entire image forming apparatus to the main body control unit 200 via the inter-CPU communication I / F unit 206. Send it out.

  The inter-CPU communication I / F unit 210 is an interface that transmits and receives control information related to image data stored in the HD 212 between the HD control unit 211 and the main body control unit 200. The HD control unit 211 controls the HD 212 so that the HD 212 stores the image data sent from the image data compression / decompression unit 207. Also, the HD control unit 211 controls the HD 212 so as to read the image data stored in the HD 212 and send the read image data to the image data compression / decompression unit 207. Control information necessary for the HD control unit 211 to control the HD 212 is received from the main body control unit 200 via the inter-CPU communication I / F unit 210. The HD 212 is configured by a nonvolatile memory.

  The image forming apparatus according to the present embodiment includes a scan image changing unit 213, a print image converting unit 214, a network communication I / F unit 215, a document feeding device control unit 216, a post-processing device control unit 217, and an operation unit. 219.

  The scan image changing unit 213 converts the image data sent from the image data selector 203 into image data described in PDL. Then, the converted image data is transferred to a host computer (not shown) connected to the image forming apparatus via the network communication I / F unit 215. PDL is an abbreviation for Page Description Language. The host computer can process image data described in PDL.

  The scan image changing unit 213 changes the PDL image data received from the host computer into image data in a format that the image forming unit 205 can form and output. Further, the changing process in the scan image changing unit 213 is performed based on the control of the main body control unit 200.

  The network communication I / F unit 215 connects the image forming apparatus to the network. The network communication I / F unit 215 transmits / receives image data and control information to / from a device (for example, a computer) connected to the network based on a predetermined communication protocol (protocol).

  The document feeder control unit 216 controls the operation of the document feeder 180 based on the control information sent from the main body control unit 200. The post-processing device control unit 217 controls the operation of the post-processing device (not shown) based on the control information sent from the main body control unit 200. As described above, the post-processing apparatus performs post-processing such as punching for punching a recording material, stapling processing for binding the recording material, and bookbinding processing for binding a plurality of recording materials and attaching a cover.

  The operation unit 219 is used when the user inputs information to the image forming apparatus. Further, the operation status of the image forming apparatus is indicated to the user via a display unit provided in the operation unit 219. Key information input via keys provided in the operation unit 219 is notified to the function control unit 209.

  Then, the function control unit 209 analyzes the command of the key information, and sends the analyzed command to the main body control unit 200 via the inter-CPU communication I / F unit 206, whereby the control information input by the user. Is notified to the main body control unit 200.

<Configuration of laser unit>
Next, the detailed configuration of the laser unit 204 in FIG. 1 will be described with reference to FIG.

  FIG. 2 is a schematic diagram showing a detailed configuration of the laser unit 204 in FIG.

  The laser unit 204 includes an exposure scanning unit 300, a laser diode 301, a beam expander 302, an imaging lens 305, and a folding mirror 306 as elements constituting the exposure apparatus according to the present embodiment. The exposure scanning unit 300 includes a polygon scanner (rotating polygon mirror) 303, a polygon motor 304, and a motor driver 310.

  The laser diode 301 generates and emits laser light. The beam expander 302 converts the laser light emitted from the laser diode 301 into a predetermined beam diameter. The polygon scanner 303 is a polyhedral mirror having a plurality of mirror surfaces for reflecting the laser beam converted into a predetermined beam diameter in the horizontal direction so as to irradiate the photosensitive drum 111. The laser light is deflected in the main scanning direction by the polygon scanner 303.

  The polygon motor 304 rotates the polygon scanner 303, and the motor driver 310 drives the polygon motor 304. The imaging lens 305 is a lens for imaging the laser beam reflected by the polygon scanner 303, and the folding mirror 306 guides the laser beam that has passed through the imaging lens 305 to the surface of the photosensitive drum 111.

  Further, the laser unit 204 includes a reflection mirror 307, a beam detection unit 308, a polygon motor control unit 309, and an FG signal generation unit 311 as elements constituting the exposure control apparatus according to the present embodiment.

  The reflection mirror 307 is a laser light detection mirror. The beam detection unit 308 detects the laser beam reflected by the reflection mirror 307 and outputs a beam detection signal (hereinafter referred to as a BD signal) to the polygon motor control unit 309. The FG signal generator 311 detects the rotational speed of the polygon motor 304 and outputs an FG signal to the polygon motor controller 309 as a rotational speed detection signal.

  The polygon motor control unit 309 controls the rotation of the polygon motor 304 by controlling the motor driver 310 in accordance with an instruction from the CPU 200a. As a method of controlling the polygon motor 304, there is a method of controlling using the FG signal generated from the FG signal generation unit 311 (FG control) as the polygon motor 304 rotates. Further, there is a method (BD control) using a BD signal output when the beam detection unit 308 detects laser light. One of the two methods can be selected by setting a register provided in the polygon motor control unit 309 by the CPU 200a in the main body control unit 200.

  In the FG control controlled using the FG signal, the polygon motor control unit 309 performs the FG signal cycle generated four times during one rotation of the polygon motor 304 and the FG control of the target speed set in advance. Compare the period. Based on the comparison result, the speed of the polygon motor 304 is controlled. That is, the polygon motor control unit 309 outputs a speed-up signal to the motor driver 310 when determining that the speed of the polygon motor 304 has not reached the target speed. When it is determined that the speed of the polygon motor 304 exceeds the target speed, a speed down signal is output to the motor driver 310.

  On the other hand, in the BD control that is controlled using the BD signal, the polygon motor control unit 309 performs BD control with a period of the BD signal that is generated six times during one rotation of the polygon motor 304 and a preset target speed. Compare the period with. Then, the speed of the polygon motor 304 is controlled based on the comparison result. That is, the polygon motor control unit 309 outputs a speed-up signal to the motor driver 310 when determining that the speed of the polygon motor 304 has not reached the target speed. When it is determined that the speed of the polygon motor 304 exceeds the target speed, a speed down signal is output to the motor driver 310.

  In either FG control or BD control, the period is determined by the polygon motor control unit 309 counting the clock generated by the reference clock generation circuit (not shown) while the polygon motor 304 makes one round. Is called.

When the target speeds of FG control and BD control are the same, the clock count value (NFG) corresponding to the target speed period under FG control and the clock count corresponding to the target speed period under BD control Between the values (NBD)
NFG = (6/4) × NBD
There is a relationship.

  In the present embodiment, the FG signal is generated four times and the BD signal is generated six times during one rotation of the polygon motor 304. However, other configurations can be realized. Further, in this embodiment, description of PLL (Phase Lock Loop) control is omitted, but it is also possible to detect the phase difference between the reference signal and the BD signal, add PLL control, and perform PLL speed control.

<Patch image formation mode>
Next, a patch image forming mode will be described as a mode (first mode) in which the rotation speed of the polygon scanner 303 needs to be controlled with high accuracy.

  FIG. 3 is a flowchart showing a sequence during patch image formation.

  During the image forming operation, high-precision image formation position control and high-precision rotation control of the polygon motor 304 are necessary. Therefore, when the image forming operation (printing operation) is started, the polygon motor control unit 309 controls the rotation of the polygon motor 304 by BD control (S301).

  Thereafter, when the number of prints reaches a predetermined number (S302), the patch image forming mode is entered (S303). Even in the patch image formation mode, since high-precision image formation position control and high-precision rotation control of the polygon motor 304 are necessary, the polygon motor control unit 309 performs rotation control of the polygon motor 304 by BD control. For example, a patch image for image correction as shown in FIG. 4 is formed, and when the patch image forming mode ends (S304), the image forming mode is entered again (S301), and a print image is formed.

  4A and 4B are schematic views showing patch images formed on the surface of the photosensitive drum in the patch image forming mode.

  The patch image here is a predetermined image formed mainly for the purpose of correcting the shift of the four color images in the color image forming apparatus, or under a predetermined condition for the purpose of correcting the density of the image. An image to be formed can be mentioned. There are also images for detecting differences in main scanning magnification due to variations in optical components.

  In FIG. 4A, a first character image 403 on the upstream side in the main scanning direction and a second character image 404 on the downstream side in the main scanning direction are used to detect the main scanning magnification and the main scanning position. It is a patch image to be formed. The first optical sensor 401 and the second optical sensor 402 each incorporate an LED and a photodiode (not shown). These sensors are installed to detect the state on the photosensitive drum by causing the LED to emit light and monitoring the reflected light from the surface of the photosensitive drum with a photodiode.

  When the first character image 403 and the second character image 404 formed on the photosensitive drum are sent in the conveying direction shown in FIG. 4A, the timing reaches the irradiation position of the LED. Detection signals P <b> 1 and P <b> 2 are detected by the first optical sensor 401 and the second optical sensor 402.

  That is, since the patch image of this example is a character image, once it passes through the optical sensors 401 and 402, two signals P1 and P2 are detected in the upper and lower oblique portions of the character. . The main scanning magnification and the main scanning position can be detected based on the detection intervals of the signals P1 and P2. For example, if the main scanning position and the main scanning magnification are both normal in the case of FIG. 4A, the detection signal of the third character image 405 is at a normal interval (W1) in FIG. 4B. Has been detected. However, since the fourth cross-shaped image 406 is shifted to the right, the detection signal interval (W2) from the second optical sensor 402 is narrowed. In this case, the main scanning magnification is increased. In addition, for example, when the third character image 405 is shifted to the right and the fourth character image 406 is shifted to the left, the main scanning magnification is decreased, and the main scanning writing position is also shifted. It shows that.

  These detection results are fed back to the CPU 200a to perform main scanning magnification correction and main scanning position deviation correction.

  The description of the patch image for detecting the shift in the sub-scanning direction of the four-color image and the print image density is omitted. However, when these images are formed on a photosensitive drum, a photosensitive belt, printing paper, etc. Accurate irradiation position control and high-precision polygon motor rotation control are required. Therefore, BD control is performed.

<BD period measurement mode>
Next, the BD cycle measurement mode will be described as a mode (first mode) in which the rotation speed of the polygon scanner 303 needs to be controlled with high accuracy.

  FIG. 5 is a flowchart showing a sequence in the mode for measuring the BD period.

  In this mode, for example, a correction value is applied when correcting a scanning line position deviation in the sub-scanning direction caused by a variation in surface accuracy of the polygon scanner 303 or a variation in light quantity on the drum surface due to a variation in reflectance for each surface. It is necessary to detect the surface. In such a case, it is used when the surface of the polygon scanner 303 is specified by measuring the BD period.

  When the polygon motor control unit 309 starts rotation of the polygon motor 304 (S501), first, the polygon motor control unit 309 performs rotation control by FG control (S502). When the polygon motor control unit 309 detects that the target speed is reached and the rotation speed is stabilized within a predetermined range (S503), the polygon motor control unit 309 performs rotation control by BD control (S504).

  After that, when the polygon motor control unit 309 detects that the rotation speed is stabilized within a predetermined range by the BD control (S505), the process proceeds to the BD cycle measurement mode (S506).

  Even though the polygon motor control unit 309 controls the rotation of the polygon motor 304 with high accuracy, jitter exists due to various factors on the feedback loop of the rotation control, and every measurement of the BD period for one round is performed. Variation will occur. Therefore, the polygon motor control unit 309 measures the BD cycle a plurality of times.

  When the measurement is completed (S507), the process proceeds to the BD cycle calculation mode (S508), the measured values for a plurality of rotations are averaged, and the surface is specified based on the average value. When the specification of the surface is completed (S509), the print standby mode is entered (S510), and image formation is started upon receipt of an image signal.

<At the start of flying>
Next, the operation at the start of flying will be described as a mode in which the rotational speed of the polygon scanner 303 does not need to be controlled with high accuracy (second mode other than the first mode).

  FIG. 6 is a timing chart at the start of flying, and FIG. 7 is a flowchart showing a sequence at the start of flying.

  Flying start here is a function for quickly setting a print standby state by starting the polygon motor 304 before an image signal is output, as described above.

  In response to the flying start signal, the polygon motor 304 is started by FG control (steps S701 and T1). After the rotational speed of the polygon motor 304 reaches the target speed, when the speed stabilizes, the process proceeds to FG control (step S702). Thereafter, the polygon motor 304 is rotationally controlled by FG control until a print start signal is input (steps S703, T2).

  After the shift to the FG control, when the print start signal is not input until a predetermined time has elapsed (steps S704 and S705), the polygon motor 304 is stopped (step S706). That is, the polygon motor 304 is stopped when, for example, the flying operation is started by the key operation of the operation unit 219 or the document set but printing is not performed or the print job is canceled halfway.

  On the other hand, if a print start signal is input, the process proceeds to BD control (T3), and rotation control is performed by BD control (step S707). When the speed is stabilized by the BD control (step S708), a print standby signal is output (steps S709, T4), and then image formation is performed by controlling the light emission of the laser diode 301 according to the image signal.

  In general, it takes several seconds from the start of the polygon motor 304 to the arrival of the target speed, whereas the time from the arrival of the target speed until the speed is stabilized is several hundred ms. Normally, at the time of flying start, the print standby state is set, that is, the speed is stabilized by BD control.

  When the BD control is performed, there is a problem in the life of the laser diode and the photosensitive drum motor as described above. Therefore, in the present embodiment, as shown in FIG. 6, the time taken to switch from the FG control speed stable state (T2) to the BD control (T3) to reach the BD control speed stable state is taken into consideration. Therefore, FG control is performed from the start of the polygon motor 304 (T1) to the timing immediately before the image signal is input (T3).

<Advantages of this embodiment>
As described above, according to the present embodiment, rotation control of the polygon motor 304 is performed by FG control in a mode that does not require the rotation accuracy of the polygon motor 304. In a mode that requires rotational accuracy, rotational control is performed by BD control. Thereby, the usage time of the laser diode and the photosensitive drum driving motor can be reduced and the life can be extended.

<Overall configuration of image forming apparatus>
Next, the overall configuration and image forming operation of the image forming apparatus according to the present embodiment will be described.

  FIG. 8 is a configuration diagram showing a schematic internal structure of the image forming apparatus according to the present embodiment.

  The image forming apparatus includes a reader unit 250 that configures the upper part of the housing, a printer unit 260 that configures the lower part of the housing, and a document feeder 180 attached to the upper part of the reader unit 250. These units are configured as a copier having an image reading function and an image forming function, for example, for forming a color image.

  The image forming apparatus is configured to be able to send and receive data to and from an external device such as a host computer via the network communication I / F unit 215. The reader unit 250 includes a scanner unit 102 including a document table glass 101, a document illumination lamp 103, and a scanning mirror 104. Further, a full-color image sensor unit 108 having a scanning mirror 105, a scanning mirror 106, a lens 107, and a CCD sensor 201 is also provided.

  The document table glass 101 is used as a table for placing a document fed by the document feeding device 180 or a document set manually. The scanner unit 102 is driven by a motor (not shown) and reciprocates in a predetermined direction. The document illumination lamp 103 is a light source that emits light that irradiates the document.

  When the scanner unit 102 scans an original placed on the original platen glass 101, the original illumination lamp 103 passes the reflected light image of the light irradiated on the original through the lens 107 through the scanning mirrors 104 to 106. Then, an image is formed on the CCD sensor 201 in the full-color image sensor unit 108 formed integrally with the three color separation filters of R (red), G (green), and B (blue) to obtain a color color separation image analog signal. The color separation image analog signal is digitized through an amplification process by an amplification circuit (not shown) in the CCD sensor 201.

  The printer unit 260 includes an image forming unit 205. The image forming unit 205 includes an exposure scanning unit 300, a photosensitive drum 111, a cleaning device 112, a pre-exposure lamp 113, a primary charger 114, a black developing device 115, and a rotating color developing device 116. Further, an intermediate transfer belt 117, a primary transfer charger 118, and a cleaning device 121 are provided.

  The exposure scanning unit 300 includes a polygon scanner 303 (see FIG. 2) and the like. Then, a laser beam modulated based on image data converted into an electrical signal by the color image sensor unit 108 of the reader unit 250 and subjected to predetermined image processing is generated, and the photosensitive drum 111 is irradiated with the laser beam. To do.

  The photosensitive drum 111 is rotationally driven by a motor (not shown), is neutralized by the pre-exposure lamp 113, and is uniformly charged to a predetermined potential by the primary charger 114. Thereafter, the laser beam emitted from the exposure scanning unit 300 is irradiated, and an electrostatic latent image is formed on the surface of the photosensitive drum 111.

  A toner image is formed on the photosensitive drum 111 by developing the electrostatic latent image formed on the photosensitive drum 111 by operating a predetermined developing device. The photosensitive drum 111 has a property that, during development, toner does not adhere to a portion that has been irradiated with laser light, and toner adheres to a portion that has not been irradiated with laser light. That is, the stronger the laser beam irradiated on the photosensitive drum 111, the thinner the toner, and vice versa.

  The rotating color developing device 116 includes developing devices 122, 123, and 124 corresponding to yellow, magenta, and cyan colors, respectively. When developing a color or black and white toner image on the photosensitive drum 111, in the case of a color image, the rotary color developing device 116 is rotated by a motor (not shown). Then, development is performed by selectively bringing a predetermined developing device out of the developing devices 122 to 124 close to the photosensitive drum 111 in accordance with each separation color to be developed. Further, when black development is performed, development is performed using a black developing device 115 disposed in the vicinity of the photosensitive drum 111. For black and white images, only the black developing device 115 is used.

  The toner image developed on the photosensitive drum 111 is primarily transferred to the intermediate transfer belt 117 by the high voltage applied by the primary transfer charger 118. In the case of color image formation, four color toner images are primarily transferred onto the intermediate transfer belt 117, and in the case of monochrome image formation, only the black toner image is primarily transferred to the intermediate transfer belt 117.

  In this embodiment, when the longitudinal dimension of the recording material to be image-formed is equal to or less than ½ of the entire circumference of the intermediate transfer belt 117, the two recording materials on the intermediate transfer belt 117 are used. It is possible to simultaneously form an image on a region corresponding to the above. After the completion of the primary transfer, the photosensitive drum 111 is subjected to an image forming process again after the residual toner on the surface is cleaned by a blade (not shown) provided in the cleaning device 112.

  In addition to the above-described components, the printer unit 260 further includes a registration roller 137, a secondary transfer roller 138, a conveyance belt 139, a heat roller fixing device (hereinafter abbreviated as a fixing device) 140, and a paper discharge flapper 141. . Further, a right cassette deck 125, a left cassette deck 126, an upper cassette deck 127, and a lower cassette deck 128 are provided. Further, a transport path 147, a transport path 142, a reversing path 143, a lower transport path 144, a refeed path 145, a refeed roller 146, a discharge roller 148, a manual feed tray 160, and the like are also provided.

  Each cassette deck 125 to 128 stores a recording material for secondary transfer of a toner image formed on the intermediate transfer belt 117 in the image forming unit 205. The recording material stored in the right cassette deck 125 is fed by a pickup roller 129 and a paper feed roller 133, and is moved to a secondary transfer position where a toner image on the intermediate transfer belt 117 is transferred to the recording material by a registration roller 137. Be transported.

  Similarly, the recording material in the left cassette deck 126 is fed by the pickup roller 130 and the paper feed roller 134, and the recording material in the upper cassette deck 127 is fed by the pickup roller 131 and the paper feed roller 135. The The recording material in the lower cassette deck 128 is fed by a pickup roller 132 and a paper feed roller 136 and is conveyed to a secondary transfer position by a registration roller 137, respectively. Note that the manual feed tray 160 is used for manual feed.

  After the primary transfer of the toner image on the photosensitive drum 111 to the intermediate transfer belt 117 in the image forming unit 205, the recording material is transferred from one of the cassette decks 125 to 128 to the position of the registration roller 137. Be transported. Then, it is further conveyed to the position of the secondary transfer roller 138 which is the secondary transfer position, and the secondary transfer onto the recording material is performed via the secondary transfer roller 138. After the secondary transfer, the intermediate transfer belt 117 is subjected to the image forming process again after the residual toner on the surface is cleaned by a blade (not shown) provided in the cleaning device 121.

  In this embodiment, the gap between the intermediate transfer belt 117 and the secondary transfer roller 138 can be arbitrarily set by operating an eccentric cam (not shown) at a desired timing. . When forming a color image, a gap is provided when a toner image of a plurality of colors is formed on the intermediate transfer belt 117, and the gap is eliminated when the toner image is transferred to a recording material. In addition, a gap is provided during standby or when the power is turned off.

  After the secondary transfer is completed, the recording material passes through the secondary transfer roller 138 and is then conveyed by the conveyor belt 139. The toner transferred onto the recording material pressurizes and heats the recording material in the fixing device 140. Fixed by. Thereafter, the paper is transported by a transport path 147 and discharged by a discharge roller 148 to a recording material discharge portion (not shown) provided outside the image forming apparatus.

  The paper discharge flapper 141 switches the discharge destination of the recording material on which the toner is fixed to the conveyance path 142 side or the discharge roller 148 side. When an image is formed on only one side of the recording material, the discharge flapper 141 is set on the discharge roller 148 side. When forming images on both sides of the recording material, the discharge flapper 141 is set on the conveyance path 142 side, the recording material conveyed by the conveyance path 142 is conveyed to the lower conveyance path 144 via the reverse path 143, Guide to the paper feed path 145. At this time, the recording material is turned over by passing through the reverse path 143 and the lower transport path 144.

  When the recording material is turned over and discharged from the image forming apparatus, the discharge flapper 141 is set on the conveyance path 142 side, the recording material is drawn into the reversing path 143, the reversing roller is reversed, and the recording material is ejected from the discharge roller 148. Transport to.

  The document feeder 180 includes a document stacking unit on which a document bundle to be copied is stacked, a feeding mechanism that feeds documents one by one from the document bundle loaded in the document stacking unit, and the like. Then, the originals to be copied are automatically exchanged (a series of processes for feeding the originals one by one from the original bundle onto the original platen glass 101 and discharging the originals when the originals are read are repeated for the number of originals). Use when.

  The present invention is not limited to the configuration of the above-described embodiment, and any configuration can be used as long as the functions shown in the claims or the functions of the configuration of the embodiment can be achieved. Is also applicable.

  In the above embodiment, the case where the image forming apparatus is a copying machine has been described as an example. However, the present invention is not limited to this, and can be applied to a printer or a multifunction machine.

  The object of the present invention can also be achieved by executing the following processing. That is, a storage medium that records a program code of software that realizes the functions of the above-described embodiments is supplied to a system or apparatus, and a computer (or CPU, MPU, etc.) of the system or apparatus is stored in the storage medium. This is the process of reading the code.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code and the storage medium storing the program code constitute the present invention.

  Moreover, the following can be used as a storage medium for supplying the program code. For example, floppy (registered trademark) disk, hard disk, magneto-optical disk, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW, magnetic tape, nonvolatile memory card, ROM or the like. Alternatively, the program code may be downloaded via a network.

  Further, the present invention includes a case where the function of the above-described embodiment is realized by executing the program code read by the computer. In addition, an OS (operating system) running on the computer performs part or all of the actual processing based on an instruction of the program code, and the functions of the above-described embodiments are realized by the processing. Is also included.

  Furthermore, a case where the functions of the above-described embodiment are realized by the following processing is also included in the present invention. That is, the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, the CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing.

1 is a functional block diagram illustrating a configuration of an image forming apparatus according to an embodiment. It is a schematic diagram which shows the detailed structure of the laser unit in FIG. It is a flowchart which shows the sequence at the time of patch image formation. It is a schematic diagram which shows the patch image formed at the time of patch image formation mode. It is a flowchart which shows the sequence at the time of the mode which measures BD period. It is a timing chart at the time of flying start. It is a flowchart which shows the sequence at the time of a flying start. 1 is a configuration diagram illustrating a schematic internal structure of an image forming apparatus according to an embodiment.

Explanation of symbols

200 Main body control unit 201 CCD sensor 202 Image processing unit 204 Laser unit 205 Image forming unit 300 Exposure scanning unit 301 Laser diode 303 Polygon scanner 304 Polygon motor 308 Beam detection unit 309 Polygon motor control unit 310 Motor driver 311 FG signal generation unit

Claims (8)

A light emitting element that is controlled to be turned on according to image data, a rotating polygon mirror that reflects a light beam output from the light emitting element by a plurality of mirrors and deflects it in a main scanning direction, and means for rotationally driving the rotating polygon mirror In an exposure control apparatus for controlling an exposure apparatus that irradiates a photoconductor with a light beam reflected by the rotary polygon mirror,
Means for detecting the light beam;
Means for detecting a rotational position of the rotary polygon mirror;
In the case of the first mode in which the rotational speed of the rotary polygon mirror needs to be controlled with high accuracy, the rotation control of the rotary polygon mirror is performed based on the detection signal of the light beam, and other than the first mode. An exposure control apparatus comprising: means for performing rotation control of the rotary polygon mirror based on a detection signal of a rotation position of the rotary polygon mirror in the case of the second mode which is a mode.   The exposure control apparatus according to claim 1, wherein the first mode is a mode in which an image is formed by irradiating the photosensitive member with the light beam.   The exposure control apparatus according to claim 1, wherein the first mode is a mode in which a photoconductor is irradiated with the light beam to form a patch image for image correction.   The exposure control apparatus according to claim 1, wherein the first mode is a mode for measuring a period of a detection signal of the light beam.   5. The second mode according to claim 1, wherein the second mode is a mode in which the rotary polygon mirror is activated to be in a standby state before the image data is output. 6. Exposure control device.   An image forming apparatus comprising the exposure control apparatus according to claim 1. A light emitting element that is controlled to be turned on according to image data, a rotating polygon mirror that reflects a light beam output from the light emitting element by a plurality of mirrors and deflects it in a main scanning direction, and means for rotationally driving the rotating polygon mirror And an exposure control apparatus processing method for controlling an exposure apparatus that irradiates a photosensitive member with a light beam reflected by the rotary polygon mirror,
Detecting the light beam;
Detecting a rotational position of the rotary polygon mirror;
In the case of the first mode in which the rotational speed of the rotary polygon mirror needs to be controlled with high accuracy, the rotation control of the rotary polygon mirror is performed based on the detection result of the light beam, and the rotation modes other than the first mode are controlled. And a step of controlling the rotation of the rotary polygon mirror based on the detection result of the rotation position of the rotary polygon mirror in the case of the second mode. A light emitting element that is controlled to be turned on according to image data, a rotating polygon mirror that reflects a light beam output from the light emitting element by a plurality of mirrors and deflects it in a main scanning direction, and means for rotationally driving the rotating polygon mirror A computer-readable program for executing a processing method of an exposure control apparatus that controls an exposure apparatus that irradiates a photosensitive member with a light beam reflected by the rotary polygon mirror,
Detecting the light beam;
Detecting a rotational position of the rotary polygon mirror;
In the case of the first mode in which the rotational speed of the rotary polygon mirror needs to be controlled with high accuracy, the rotation control of the rotary polygon mirror is performed based on the detection result of the light beam, and the rotation modes other than the first mode are controlled. In the case of the second mode, which is a mode, the program includes a step of performing rotation control of the rotary polygon mirror based on a detection result of a rotation position of the rotary polygon mirror.

Images