JP2017126056A - Optical scan device, image formation device, and optical scan control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a specified timing for performing a specified process, in an optical scan device for reciprocal scanning.SOLUTION: An optical scan device includes optical beam emitting means for emitting an optical beam, a scan body which makes the optical beam scan reciprocally by reflecting the optical beam while performing scan movement, a plurality of pieces of optical detection means arranged at different positions in a range of reciprocal scanning of the optical beam, and control means which makes the optical beam emitting means continue emission of the optical beam and makes continuation of the optical beam emission to be finished when the optical beam is detected by each of the plurality of pieces of optical detection means, and starts a specified process based on a plurality of time points when the optical beam is detected by each of the plurality of pieces of optical detection means.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical scanning device, an image forming apparatus, and an optical scanning control method for performing processing related to optical scanning.

  An image forming apparatus such as a copying machine, a facsimile machine, or a multifunction machine equipped with the functions of a plurality of these apparatuses includes an optical scanning device for forming a latent image on a scanning target.

  In this regard, in the optical scanning device, laser light emitted from a semiconductor laser (LD: laser diode) that is a light source is reflected by a scanning body that scans and moves, so that the laser light scans the scanned body. A latent image is formed on the scanned object.

  However, if the laser beam output is continued, the temperature of the semiconductor laser that outputs the laser beam rises. As the temperature rises, the output of the semiconductor laser becomes weak even if the same current is supplied to the semiconductor laser. Even if the same semiconductor laser is used, the output of the semiconductor laser is weak even if the same current is supplied to the semiconductor laser due to factors such as aging.

  For this reason, the optical scanning device performs APC (Auto Power Control) at a predetermined timing such as when the laser is initialized or every line scan in order to keep the output of the semiconductor laser constant. Specifically, in the APC, the LD drive voltage is automatically controlled so that the output current of a photodiode (PD: Photodiode) built in the semiconductor laser module becomes constant. APC is also called a sample hold mode.

  Here, the APC is roughly classified into an initial APC and a steady APC. The initial APC is a process performed when the laser is initialized. The initial APC is also called initialization or 1st APC. On the other hand, steady APC is APC performed for each line scan. Stationary APC is also called line APC or simply APC.

  An example of a technique related to such steady APC is described in Patent Document 1. After the initial APC is performed, the semiconductor laser output can always be kept constant by performing the steady APC for each line scan at a predetermined timing using the configuration described in Patent Document 1.

  On the other hand, in the optical scanning device, in order to reduce the size and cost of the device, reduce power consumption, heat generation and noise, and shorten the time required to form the first image, the scanning body is driven. The use of MEMS (Micro Electro Mechanical System) as a device is proposed in Patent Document 2, for example.

  In an optical scanning device using MEMS, laser light emitted from a semiconductor laser as a light source is reflected by a scanning body that reciprocally scans by MEMS, whereby the laser light reciprocally scans the scanned body. As a result, a latent image is formed on the scanned object.

JP2015-11099A JP 2012-37578 A

  In the configuration described in Patent Document 1 described above, a polygon mirror is used as a scanning device driving device. Then, the laser light emitted from the LD is reflected by each surface of the polygon mirror in a constant speed rotation state by a rotation drive unit such as a motor.

  At this time, the polygon mirror scans the laser beam at an equal angle by rotating in a predetermined direction around a rotation axis perpendicular to the paper surface. That is, in the configuration described in Patent Document 1, since the polygon mirror operates in this way, the laser beam is unidirectionally scanned on the scanning target.

  In such a one-way scanning configuration, a BD (Beam Detect) sensor is provided at one end of the scanning range, and a steady APC is executed once per line when the BD sensor detects a light beam. It was possible to do.

  On the other hand, in the optical scanning device, a change in the movement characteristics of the scanning body may occur due to a change in environmental characteristics, aging deterioration, or the like, and the scanning range or the like may change. When the scanning range or the like changes, there arises a problem that the latent image writing position is shifted and the image quality is deteriorated. Here, if the BD sensor is provided as described above, it is also possible to control the scanning body so that the scanning range becomes a predetermined range based on the timing when the BD sensor detects the light beam.

  However, as described in Patent Document 2, when MEMS is used as a scanning body driving device, the laser beam reciprocates over the scanning body as described above. For this reason, it is not possible to directly adopt the method of Patent Document 1 or the like in which steady APC is executed once a line is detected by the BD sensor as a trigger, or operation control of the scanning body is executed. The problem arises.

  This is because when the laser beam reciprocally scans the object to be scanned, it is necessary to detect four times of laser light per cycle of the reciprocating scan as a reference for steady APC or scanning control. This is because there is no description about at what timing after the initial APC it is necessary to shift to the steady APC and continue the detection of these standards.

  Accordingly, the present invention provides an optical scanning device, an image forming apparatus, and an optical scanning control method capable of detecting a predetermined timing for executing predetermined processing in an optical scanning device that performs reciprocating scanning. With the goal.

  According to a first aspect of the present invention, a light beam emitting unit that emits a light beam, a scanning body that reciprocally scans the light beam by reflecting the light beam while performing a scanning motion, A plurality of light detecting means arranged at different positions within a reciprocating scanning range; and the light beam emitting means continues to emit the light beam, and the light beam is detected by each of the plurality of light detecting means. As a trigger, the control unit includes a control unit that ends the emission of the light beam and starts predetermined processing based on a plurality of time points when the light beam is detected by the plurality of light detection units. An optical scanning device is provided.

  According to a second aspect of the present invention, there is provided an image forming apparatus comprising the optical scanning device provided according to the above aspect of the present invention, wherein an electrostatic latent image is generated by the light beam emitted by the light beam emitting means. An image forming apparatus is provided.

  According to a third aspect of the present invention, a light beam emitting unit that emits a light beam, a scanning body that reciprocally scans the light beam by reflecting the light beam while performing a scanning motion, A light scanning control method performed by a light scanning device including a plurality of light detection means arranged at different positions in a reciprocating scanning range, wherein the light beam emitting means continues to emit the light beam, When the light beam is detected by each of the plurality of light detection means, the continuation of the emission of the light beam is terminated, and a plurality of time points at which the light beam is detected by each of the plurality of light detection means are determined. An optical scanning control method characterized by starting a predetermined process based on a reference is provided.

  According to the present invention, it is possible to detect a predetermined timing for executing a predetermined process in an optical scanning device that performs reciprocating scanning.

It is a figure explaining the scanning by the MEMS mirror in each embodiment of the present invention. It is a figure showing about the detection of the BD sensor in each embodiment of the present invention. It is a figure showing the basic composition of the optical scanning unit in the 1st embodiment etc. of the present invention. It is a flowchart showing the transfer operation | movement to steady APC in each embodiment etc. of this invention. It is a timing chart figure explaining the shift to regular APC in each embodiment of the present invention. It is a flowchart showing the operation | movement by steady APC in the 1st Embodiment etc. of this invention. It is a figure showing the fundamental structure of the optical scanning unit in the 2nd Embodiment etc. of this invention. It is a flowchart showing the transfer operation | movement to steady APC in the 3rd Embodiment etc. of this invention. It is a figure showing about the detection of the BD sensor in the 5th Embodiment of this invention. It is a figure showing the fundamental structure of the optical scanning unit in the 5th Embodiment of this invention. It is a flowchart showing the transfer operation | movement to steady APC in the 5th Embodiment of this invention. It is a timing chart figure explaining the shift to regular APC in the 5th embodiment of the present invention. It is a timing chart figure explaining steady APC when an optical axis gap arises. It is a flowchart showing the operation | movement by stationary APC in the 6th Embodiment of this invention. It is a timing chart explaining steady APC when an optical axis gap arises in a 6th embodiment of the present invention. 1 is a diagram illustrating a basic configuration of an image forming apparatus according to each embodiment of the present invention.

  First, the outline of each of the seven embodiments of the present invention will be described.

  The optical scanning unit according to the first embodiment of the present invention continues to forcibly turn on the laser light until it is detected by the left and right BD sensors four or more times when shifting to the steady APC after the initial APC. This makes it possible to execute processing such as steady APC in an optical scanning device that performs reciprocal scanning that requires four BD detections per cycle. Specifically, it is possible to run a steady APC sequence or the like based on the four BD detection timings detected first.

  Further, the optical scanning unit according to the second embodiment of the present invention performs a process of controlling the scanning motion of the scanning body based on the interval of the four BD detection timings in addition to running the above-described steady APC sequence. Do. Specifically, correction is performed so that the scanning angle is fixed to a predetermined angle by controlling the deflection operation of the MEMS driving unit.

  Furthermore, the optical scanning unit according to the third embodiment of the present invention controls the MEMS mirror to be surely in a steady state after the initial APC is executed before the above-described steady APC sequence is run.

  Furthermore, the optical scanning unit according to the fourth embodiment of the present invention executes the above-described steady APC sequence based on an arbitrary number of BD detection timings among the four BD detection timings detected first.

Furthermore, the optical scanning unit according to the fifth embodiment of the present invention executes the above-described steady APC sequence based on two BD detection timings first detected by one BD sensor.
Furthermore, the optical scanning unit according to the sixth embodiment of the present invention copes with a case where an optical axis shift occurs in the BD sensor while the steady APC sequence is running.

Furthermore, the seventh embodiment of the present invention is an image forming apparatus on which any one of the above-described six optical scanning units is mounted. In the seventh embodiment, an electrostatic latent image is formed by a light beam emitted from any of the optical scanning units of the six embodiments described above.
The above is the outline of each of the seven embodiments of the present invention.

<First Embodiment>
Next, the first embodiment, which is a basic embodiment, will be described with reference to the drawings.

  First, the relationship between the laser beam emitted from the optical scanning unit 100 according to this embodiment, the photosensitive drum 300, the MEMS mirror, and the like will be described with reference to FIG.

  Referring to FIG. 1, a photosensitive drum 300, an LD unit 11, a MEMS mirror 12, a left BD sensor 13, and a right BD sensor 14 are illustrated. This is a part particularly relevant to the present description in the image forming apparatus, and the other parts are not shown in the figure. The LD unit 11, the MEMS mirror 12, the left BD sensor 13, and the right BD sensor 14 are included in the optical scanning unit 100 according to this embodiment.

  The LD unit 11 is a part that emits laser light toward the MEMS mirror 12 that is a scanning body.

  The MEMS mirror 12 is, for example, electrostatic unipolar drive. In the present embodiment, by applying a drive voltage having a predetermined polarity to the electrodes, the photosensitive drum 300 is vibrated so that the mirror surface is deflected, and the laser light emitted from the LD unit 11 is emitted. Reflected by the mirror surface and shaken in the axial direction of the photosensitive drum 300, that is, reciprocally scanned. More specifically, when the MEMS mirror 12 is deflected and oscillated, the reflection direction of the laser light emitted from the LD unit 11 is deflected, so that the latent image forming region El of the photosensitive drum 300 (in FIG. The scanning range E2 (indicated as “E2” in the drawing) including the “.” Is reciprocally scanned.

  Each of the left BD sensor 13 and the right BD sensor 14 is a chip-formed BD sensor, and each includes a photodiode. Then, the left BD sensor 13 and the right BD sensor 14 detect the laser light emitted from the LD unit 11 by a photodiode along with the deflection vibration of the MEMS mirror 12. The left BD sensor 13 and the right BD sensor 14 output a detection signal having a level corresponding to the amount of laser light detected by these photodiodes. The output destination will be described later with reference to FIG.

  The left BD sensor 13 and the right BD sensor 14 are arranged at appropriate positions outside the latent image forming area El of the photosensitive drum 300 and inside the scanning range E2. More specifically, in the direction facing the photosensitive drum 300 from the MEMS mirror 12, the left BD sensor 13 is disposed at the left end of the scanning range E2, and the right BD sensor 14 is disposed at the right end of the scanning range E2. ing.

  In the following description, for convenience of description, scanning from the left BD sensor 13 toward the right BD sensor 14 is referred to as A-direction scanning, and scanning from the right BD sensor 14 toward the left BD sensor 13 is referred to as B-direction scanning. .

  Next, referring to FIG. 2, scanning in each direction accompanying the deflection vibration of the MEMS mirror 12 and detection of laser light by the left BD sensor 13 and the right BD sensor 14 will be described.

  As shown in FIG. 2, in the reciprocating scan, the left BD sensor 13 at the left end in the scanning range E2 detects the B direction scan, and the left BD sensor 13 outputs a detection signal along with this (see “ Equivalent to S1). Next, after the scanning of the light beam is switched to the A-direction scanning, the A-direction scanning is detected by the left BD sensor 13, and accordingly, the left BD sensor 13 outputs a detection signal (corresponding to “S2” in the figure). .

  Next, scanning in the A direction is detected by the right BD sensor 14 at the right end, and accordingly, the right BD sensor 14 outputs a detection signal (corresponding to “S3” in the figure). Further, after the scanning of the light beam is switched to the B-direction scanning, the right-side BD sensor 14 detects the B-direction scanning, and accordingly, the right-side BD sensor 14 outputs a detection signal (corresponding to “S4” in the figure). .

  Since the MEMS mirror 12 repeats such a reciprocating scanning operation of the light beam, the left BD sensor 13 and the right BD sensor 14 also repeat the above detection (corresponding to “S5 and S6” in the figure and subsequent detections). .

  As described above, the reflection of the laser beam by the MEMS mirror 12 and the relationship between the scanning and the associated scanning 300 and the detection of the left BD sensor 13 and the right BD sensor 14 have been described with reference to FIGS.

  Next, functional blocks included in the optical scanning unit 100 will be described with reference to FIG. Referring to FIG. 3, the optical scanning unit 100 includes an LD unit 11, a MEMS mirror 12, a left BD sensor 13, a right BD sensor 14, and an APC control unit 20.

  Here, since the LD unit 11 to the right BD sensor 14 have been described with reference to FIG. 1, overlapping description will be omitted. However, the connection relationship with other parts of these parts is not described in FIG. 1 and will be described below.

  When the left BD sensor 13 and the right BD sensor 14 detect the beam light, the detection signal is output as described above. The output detection signal is input to the APC control unit 20.

  The APC control unit 20 is a control unit for performing APC, and operates as a controller that always keeps the amount of laser light emitted from the LD unit 11 constant. For this purpose, the APC control unit 20 is connected to the LD unit 11 and has a function of controlling the drive current of the LD unit 11.

  Here, in the LD unit 11 of the present embodiment, a monitoring photodiode that includes a part of the light emitted from the LD unit 11 and outputs an output current corresponding to the amount of received light is included. The APC control unit 20 receives an output current corresponding to the amount of received light output from the photodiode. Next, the APC control unit 20 controls the drive current of the LD unit 11 based on the received output current so that the output current is always constant.

  Specifically, the drive current of the LD unit 11 is corrected so that the amount of laser light is always constant based on the output current corresponding to the amount of received light fed back from the photodiode. Then, the corrected drive current is output to the laser driver in the LD unit 11. The LD unit 11 emits laser light with a light amount corresponding to the drive current input from the APC control unit 20.

  As a result, the current corresponding to the amount of light received by the photodiode is always constant. That is, the amount of laser light emitted from the LD unit 11 is always constant.

  The above is the outline of APC. Here, as described in [Background Art], APC includes an initial APC and a steady APC.

  Of these two APCs, the initial APC is a process performed when the laser is initialized. Therefore, the initial APC may be executed by causing the LD unit 11 to turn on the laser beam when the optical scanning unit 100 is initialized, that is, when the optical scanning unit 100 is activated.

  However, since steady APC needs to be performed for each line scan, it cannot be performed at an arbitrary timing. Therefore, the optical scanning unit 100 according to the present embodiment shifts to the steady APC based on the detection signals from the left BD sensor 13 and the right BD sensor 14 after executing the initial APC. The transition to the steady APC will be described with reference to the flowchart of FIG. 4 and the timing chart of FIG.

  First, when the optical scanning unit 100 is activated, the optical scanning unit 100 causes the LD unit 11 to turn on the laser light and executes the above-described initial APC (step A11).

  Next, the APC control unit 20 controls the drive current of the LD unit 11 to cause the LD unit 11 to start forced lighting of the laser light (step A12). Instead of starting forced lighting for the first time in step A12, for example, forced lighting may be continued after starting lighting in the initial APC of step A11.

  Next, it waits until the detection signal of a laser beam is input into the APC control part 20 from the left BD sensor 13 or the right BD sensor 14 (No in step A13). Here, in this explanation example, the case where the B-direction scanning is performed first and this is detected by the left BD sensor 13 will be described as an example. That is, the detection signal is input twice from the right BD sensor 14 after the detection signal is input twice from the left BD sensor 13. This means that detection signals are output as in S1, S2, S3 and S4 in FIG.

  First, the left BD sensor 13 detects a laser beam and outputs a detection signal. In this way, when it is determined that the first detection has been made, the process proceeds to step A14 (Yes in step A13). Then, from the first detection time, counting of time for one cycle of reciprocating scanning by the MEMS mirror 12 is started (step A14). The time for one cycle of reciprocating scanning by the MEMS mirror 12 is determined by the specifications of the MEMS mirror 12. Therefore, for example, by referring to the specifications of the manufacturer that created the MEMS mirror 12, the time required for one cycle of the reciprocating scan by the MEMS mirror 12, that is, the time for one cycle of the reciprocating scan by the MEMS mirror 12 is grasped. Can do. Instead of doing so, the time for one cycle of reciprocating scanning by the MEMS mirror 12 may be measured in advance by a measuring device.

  The description associated with step A14 is shown as nAPC1 in FIG. It is assumed that the processes of nAPC1, nAPC2, nAPC3, and nAPC4 are executed by four corresponding circuits.

  As described in the timing chart, the circuit corresponding to nAPC1 does not count for steady APC until the first detection, and starts counting for steady APC when triggered by the first detection. To do. That is, as described in the figure, since the first detection is waited, the period for starting steady APC is extended.

  Next, as in step A13, the process waits until there is a second detection (No in step A15). If there is a second detection (Yes in step A15), the process proceeds to step A16. Then, as in step A14, counting of one cycle of reciprocating scanning by the MEMS mirror 12 is started from the second detection time (step A16).

  The description associated with step A16 is shown as nAPC2 in FIG.

  As described in the timing chart, the circuit corresponding to nAPC2 does not count for steady APC until the second detection, and starts counting for steady APC in response to the second detection. To do. That is, as shown in the drawing, the period for starting APC is extended because the second detection is waited.

  Thereafter, processing similar to Step A13 and Step A14, and Step A15 and Step A16 is performed in Step A17 and Step A18, and Step A19 and Step A20.

  Then, when the fourth detection is finished in step A19 and step A20 is finished, the laser unit forcibly turns on the laser light by the LD unit 11 is finished under the control of the APC control unit 20 (step A21).

  With the above operation, the transition sequence to the steady APC is completed, and thereafter the steady APC is executed.

  Next, the operation when performing steady APC will be described with reference to the flowchart of FIG.

  First, it waits until the period of any one of the first period to the fourth period is close to the lapse of time for one period of reciprocating scanning (No in step A31).

  In this regard, the four circuits corresponding to the above-described nAPC1, nAPC2, nAPC3, and nAPC4 approach the time elapsed for one cycle of the reciprocating scan from the input of the previous detection signal (Yes in step A31), and the nAPC in FIG. The signal output to the circuit corresponding to is set to low level. Then, the signal output from the circuit corresponding to nAPC also becomes a low level triggered by the change in the signal. Then, the APC control unit 20 controls the control voltage of the LD unit 11 to cause the LD unit 11 to emit laser light (step A32). That is, the laser light is emitted immediately before the timing when the left BD sensor 13 and the right BD sensor 14 will detect the laser light.

  It is assumed that the APC control unit 20 includes circuits corresponding to nAPC1, nAPC2, nAPC3, nAPC4, and nAPC. Further, in this way, nAPC outputs a low level signal in accordance with the output of any one of nAPC1, nAPC2, nAPC3, and nAPC4. Therefore, as shown in FIG. 5, nAPC is nAPC1, nAPC2 , NAPC3 and nAPC4.

  Next, the APC control unit 20 makes the output current of the photodiode constant based on the output current of the photodiode in the LD unit 11 as described above, that is, the output of the laser light emitted from the LD unit 11. The drive current of the LD unit 11 is adjusted so that becomes constant (step A33).

  Next, standby is performed until the laser beam being emitted is detected by the left BD sensor 13 and the right BD sensor 14 (step A34). If the laser beam is detected, the process proceeds to step A35.

  In step A35, the APC control unit 20 controls the drive current to cause the LD unit 11 to finish emitting laser light (step A35). The circuits corresponding to nAPC1, nAPC2, nAPC3, and nAPC4 that output the low level signal in step A31 again count the time for one cycle of the reciprocating scan.

Then, the process returns to step A31, and waits until the time for one cycle of the reciprocating scan approaches in another cycle (No in step A31), and the subsequent processing is repeated.
With the above operation, steady APC can be realized at an appropriate timing.

  According to the first embodiment described above, it is possible to execute processing such as steady APC in the optical scanning device that performs reciprocal scanning. Specifically, there is an effect that a steady APC sequence or the like can be run based on the detection timings of the four BD sensors detected first.

  Moreover, in 1st Embodiment, it transfers to steady APC, without depending on the phase relationship of a MEMS drive voltage and a MEMS locus. For this reason, even if the phase relationship between the MEMS drive voltage and the MEMS trajectory varies due to inter-individual, environmental characteristics, and secular change, the processing of this embodiment is not affected. In this regard, when the MEMS is a capacitance type, the phase relationship between the MEMS drive voltage and the MEMS trajectory cannot be uniquely estimated, and thus this embodiment is particularly effective.

  Furthermore, since the first embodiment runs a sequence according to the MEMS cycle time, it is not necessary to consider the APC start timing in a complicated manner.

<Second Embodiment>
Next, the configuration of the optical scanning unit 200 according to the second embodiment will be described with reference to FIG. Here, the optical scanning unit 200 includes functional blocks similar to the optical scanning unit 100 of the first embodiment described above. Then, the optical scanning unit 200 executes the steady APC sequence in the same transition sequence as the optical scanning unit 100. That is, the optical scanning unit 100 and the optical scanning unit 200 are common in this respect. In addition, about this common point, since it becomes redundant description, description for the second time is abbreviate | omitted.

  On the other hand, in addition to such processing, the optical scanning unit 200 of the present embodiment performs processing for controlling the scanning motion of the scanning body based on the interval between the four BD detection timings detected in step A34. Specifically, correction is performed so that the scanning angle is fixed to a predetermined angle by controlling the deflection operation of the MEMS driving unit. This point will be described in detail below.

  First, functional blocks included in the optical scanning unit 200 will be described. Referring to FIG. 4, the optical scanning unit 200 includes the LD unit 11, the MEMS mirror 12, the left BD sensor 13, the right BD sensor 14, and the APC control unit 20, as well as the optical scanning unit 100, and further includes a timer unit 15, A comparison unit 16, a storage unit 17, a PWM (Pulse Width Modulation) control unit 18, a MEMS drive unit 19, and an APC control unit 20 are provided.

  The time measuring unit 15 receives the detection signal from the left BD sensor 13 twice in succession until the detection signal is input from the right BD sensor 14 or the detection signal from the right BD sensor 14 twice. The time interval from the continuous input until the detection signal is input from the left BD sensor 13 and the time interval between the signs are measured, and the measurement result is output to the comparison unit 16. The timing at which the detection signals are input from the left BD sensor 13 and the right BD sensor 14 is the timing at which the left BD sensor 13 and the right BD sensor 14 detect the laser beam in step A34.

  The comparison unit 16 reads a preset reference time interval from the storage unit 17. Then, the comparison unit 16 compares the time interval measured by the time measuring unit 15 with a preset reference time interval, and corrects the correction value so that the scanning motion range of the MEMS mirror 12 becomes the preset reference range. And the correction value is output to the PWM control unit 18.

The PWM control unit 18 refers to a lookup table stored in itself (or stored in the storage unit 17), and adjusts the duty ratio of the PWM signal according to the correction value input from the comparison unit 16. Get control value. Next, the PWM control unit 18 temporarily stores the PWM control value. The PWM controller 18 reads out the stored PWM control value at a predetermined timing, adjusts the duty ratio, and outputs a PWM signal. The predetermined timing is, for example, a timing at which the scanning direction is switched.
The MEMS drive unit 19 controls the deflection operation of the MEMS mirror 12 based on the PWM signal output from the PWM control unit 18.
As a result, the scanning angle of the scanning range E2 described with reference to FIG. 2 is corrected so as to be fixed to a predetermined angle.

  Here, the timing unit 15, the comparison unit 16, the storage unit 17, the PWM control unit 18, and the MEMS drive unit 19 control the deflection operation of the MEMS mirror 12 based on the detection of the laser beam in step A34 shown in FIG. The correction is performed so that the scanning angle is fixed to a predetermined angle.

  In the second embodiment described above, the same effect as that of the first embodiment is obtained, and further, the deflection operation of the MEMS mirror 12 is controlled based on the detection of the laser beam during the steady APC, and the scanning angle is set. There is an effect that the predetermined angle can be obtained.

<Third Embodiment>
Next, processing of the third embodiment will be described with reference to the flowchart of FIG. Here, the third embodiment can be realized by a configuration in which the MEMS driving unit 19 is added to the optical scanning unit 100 in the first embodiment described above. Moreover, it is also realizable by the structure of the optical scanning unit 200 in 2nd Embodiment mentioned above.

  In the third embodiment, the steady APC sequence is executed in the same transition sequence as in the first embodiment and the second embodiment described above. That is, the process described with reference to FIGS. 4 and 6 is executed. Since these configurations and processes are redundantly described, repeated descriptions are omitted.

  In addition, in the third embodiment, after step A11 in FIG. 4, prior to running the steady APC sequence, the processing of step A41 and step A42 is further performed to ensure that the MEMS mirror is in a steady state. This is different from the other embodiments in that it is performed. Hereinafter, this difference will be described in detail with reference to the flowchart of FIG.

  Referring to FIG. 8, first, the initial APC is executed (step A11) as in the process with reference to FIG. Next, prior to running the steady APC sequence, after the initial APC is executed, control is performed to ensure that the MEMS mirror 12 is in a steady state.

  Specifically, in order for the MEMS mirror 12 to perform a predetermined deflection operation, the MEMS drive unit 19 is operated at a high drive frequency to start the vibration operation of the MEMS mirror 12, and then a predetermined time is increased. The frequency is adjusted by the procedure of setting the drive frequency to the resonance frequency (step A41).

  Then, it is determined whether or not the deflection operation of the MEMS mirror 12 is in a steady state (step A42). For example, when the MEMS drive unit 19 is currently operated at a high frequency or when the MEMS drive unit 19 is just operated at a resonance frequency, the deflection operation of the MEMS mirror 12 is still in a steady state. (No in step A42) and return to step A41.

  On the other hand, when a predetermined time has elapsed since the MEMS drive unit 19 was operated at the resonance frequency, it is determined that the deflection operation of the MEMS mirror 12 has become a steady state, and the same process as described above with reference to FIG. Then, processing for shifting to steady APC after step A12 is executed (processing after step A12 and step A13).

  In the third embodiment described above, prior to running the steady APC sequence, control is performed to ensure that the MEMS mirror 12 is in a steady state after the initial APC is executed. Therefore, in the third embodiment, there is an effect that laser light can be detected in step A13, step A15, step A17, and step A19 at a more accurate timing in each cycle.

<Fourth Embodiment>
Next, a fourth embodiment, which is a modification of the first embodiment described above, will be described. In each embodiment described above, the steady APC sequence is run based on the four BD detection timings detected first.

  In this regard, from the viewpoint of more appropriately performing steady APC, laser light is output at a predetermined timing four times for each deflection operation of the MEMS mirror 12, and the LD unit 11 is driven based on the received light amount of the laser light. It is preferable to control the current.

  Further, as in the second embodiment, even when correction is performed so that the scanning angle is fixed to a predetermined angle by controlling the deflection operation of the MEMS driving unit 19 based on the timing at which the laser beam is detected. It is preferable to detect the laser beam at a predetermined timing four times per cycle.

  However, for that purpose, it is necessary to prepare four circuits corresponding to nAPC1, nAPC2, nAPC3, and nAPC4 described with reference to FIG. In addition, it is necessary to perform control with laser light output at a predetermined timing four times per cycle.

  Therefore, in the present embodiment, steady APC is executed not by four times per cycle but by a number less than that. For example, two circuits are provided: a circuit corresponding to the left BD sensor 13 (circuit corresponding to either nAPC1 or nAPC2) and a circuit corresponding to the right BD sensor 14 (circuit corresponding to any of nAPC3 and nAPC4). .

  Then, the logical product of the outputs of these two circuits is nAPC, and the laser light output in step A32 and subsequent processing are performed. That is, the control with the output of the laser beam is performed at a predetermined timing, for example, twice, not four times per cycle.

  In the fourth embodiment, by doing this, the number of necessary circuits can be reduced, and the entire circuit can be simplified.

<Fifth Embodiment>
Next, a fifth embodiment will be described with reference to the drawings. In each of the above-described embodiments, as described with reference to FIG. 1, in the optical scanning device 100 and the optical scanning device 200 that perform reciprocal scanning, two BD sensors of the left BD sensor 13 and the right BD sensor 14 are provided. . Then, the steady APC sequence was run based on the BD detection timing at which the laser light was detected by these two BD sensors.

  However, there may be a case where only one BD sensor is provided. Therefore, in this embodiment, even when only one BD sensor is provided, steady APC can be realized at an appropriate timing.

  Here, the relationship among the laser beam emitted from the LD unit 11, the photosensitive drum 300, the MEMS mirror, and the like in the present embodiment is the same as the above-described relationship described with reference to FIG. The detailed explanation is omitted. However, as described above, in the present embodiment, only one BD sensor is provided. Specifically, only one of the left BD sensor 13 and the right BD sensor 14 is provided. That is, the sensors provided on both sides in each of the above-described embodiments are provided only on one side. Hereinafter, the sensor of this embodiment is referred to as a one-side BD sensor 21.

  Next, with reference to FIG. 9, the scanning in each direction accompanying the deflection vibration of the MEMS mirror 12 and the detection of the laser beam by the one-side BD sensor 21 will be described. In FIG. 9, it is assumed that the one-side BD sensor 21 is provided at the left end portion in the scanning range E <b> 2 like the left-side BD sensor 13, but the one-side BD sensor 21 is the same as the right-side BD sensor 14. It is good also as providing in the right end part in the scanning range E2.

  As shown in FIG. 9, in the reciprocating scanning, the B-direction scanning is detected by the one-side BD sensor 21 at the left end portion in the scanning range E2, and accordingly, the one-side BD sensor 21 outputs a detection signal (“ Equivalent to S11 "). Next, after the scanning of the light beam is switched to the A-direction scanning, the A-side scanning is detected by the one-side BD sensor 21, and accordingly, the one-side BD sensor 21 outputs a detection signal (corresponding to “S12” in the figure). .

  Since the MEMS mirror 12 repeats the reciprocating scanning operation of the light beam, the one-side BD sensor 21 also repeats the above-described detection (“S13 and S14” in the figure, which corresponds to the subsequent detection).

  As described above, the reflection of the laser beam by the MEMS mirror 12 and the relation between the scanning and the associated scanning 300 and the detection of the laser beam by the one-side BD sensor 21 have been described with reference to FIGS.

  Next, functional blocks included in the optical scanning unit 101 of the present embodiment will be described with reference to FIG. Referring to FIG. 10, the optical scanning unit 101 includes an LD unit 11, a MEMS mirror 12, a one-side BD sensor 21, and an APC control unit 20.

The optical scanning unit 101 is different from the optical scanning unit 100 described above with reference to FIG. 3 in that it includes a one-side BD sensor 21. The one-side BD sensor 21 is a BD sensor provided at either the left end or the right end in the scanning range E2 instead of the left BD sensor 13 and the right BD sensor 14 as described above. The function of the one-side BD sensor 21 is the same as that of the left-side BD sensor 13 and the right-side BD sensor 14. When a beam light is detected, a detection signal is input to the APC control unit 20.
Regarding the other points, the optical scanning unit 101 is the same as the optical scanning unit 100 described above, and thus a duplicate description is omitted.

  Further, like the optical scanning unit 100, the optical scanning unit 101 of the present embodiment shifts to steady APC based on the detection signal from the one-side BD sensor 21 after the initial APC is executed. The transition to the steady APC will be described with reference to the flowchart of FIG. 11 and the timing chart of FIG.

  Here, step A11, step A12, and step A21 in FIG. 11 are the same as the processing of the step having the same name described with reference to FIG.

  First, when the optical scanning unit 101 is activated, the optical scanning unit 101 executes initial APC (step A11). Then, the APC control unit 20 controls the drive current of the LD unit 11 to cause the LD unit 11 to start forcibly lighting the laser light (step A12).

  Next, steps A51 to A54 are performed as the processing of this embodiment. Note that these processes use a detection signal of the one-side BD sensor 21, and are substantially performed from step A13 to step A16 performed using the detection signals of the left BD sensor 13 and the right BD sensor 14. It is the same content as the process.

  Wait until the detection signal of the laser beam is input from the one-side BD sensor 21 to the APC control unit 20 (No in step A53). In the following description, detection signals are output as in S11, S12, S13, and S14 in FIG.

  First, the one-side BD sensor 21 outputs a detection signal by detecting the laser beam once. In this way, when it is determined that the first detection has been made, the process proceeds to step A52 (Yes in step A51). Then, from the first detection time, counting of time for one cycle of reciprocating scanning by the MEMS mirror 12 is started (step A52).

  The description associated with step A52 is shown as nAPC1 in FIG. It is assumed that the processes of nAPC1 and nAPC2 are executed by two circuits corresponding to each.

  As described in the timing chart, the circuit corresponding to nAPC1 does not count for steady APC until the first detection, and starts counting for steady APC when triggered by the first detection. To do. That is, as described in the figure, since the first detection is waited, the period for starting steady APC is extended.

  Next, as in step A51, the process waits until there is a second detection by the one-side BD sensor 21 (No in step A53). If there is a second detection (Yes in step A53), step Proceed to A54. Then, similarly to step A52, counting of the time for one cycle of reciprocating scanning by the MEMS mirror 12 is started from the second detection time (step A54).

  The description associated with step A54 is shown as nAPC2 in FIG.

  As described in the timing chart, the circuit corresponding to nAPC2 does not count for steady APC until the second detection, and starts counting for steady APC in response to the second detection. To do. That is, as shown in the drawing, the period for starting APC is extended because the second detection is waited.

  Then, when the second detection is finished in step A53 and step A54 is finished, the laser unit forcibly lighting the LD unit 11 is finished under the control of the APC control unit 20 (step A21).

  With the above operation, the transition sequence to the steady APC is completed, and thereafter, the steady APC is executed at an appropriate timing determined based on the detection of the laser beam by the one-side BD sensor 21 in the transition sequence. Become. The operation when performing steady APC is as described above with reference to FIG.

  The embodiment described above has an effect that even when only one BD sensor is provided, steady APC can be realized at an appropriate timing.

<Sixth Embodiment>
Next, a sixth embodiment will be described with reference to the drawings. In each of the above-described embodiments, for example, as illustrated in FIGS. 5 and 12, until the left BD sensor 13, the right BD sensor 14, or the one-side BD sensor 21 detects a laser beam and outputs a detection signal, Counting for steady APC was started with the output of the detection signal without counting for APC. That is, as shown in FIG. 5 and FIG. 12, the period for starting APC is extended by waiting for the output of the detection signal.

  For example, when the detection is performed four times in this way, the transition sequence to the steady APC is completed, and thereafter the steady APC is executed at an appropriate timing determined based on the detection of the laser beam in the transition sequence. Was.

  In this case, at the first time of steady APC, when the time elapse of one cycle of the reciprocating scan approaches from the reference with the timing at which the laser beam is detected in the transition sequence to steady APC (Yes in step A31 in FIG. 6). ), The processing from step A32 to step A35 in FIG. 6 was performed.

  Then, from the next time, when the input of the detection signal in the previous process is used as a new reference, when the time for one cycle of the reciprocating scanning is approached from this new reference (Yes in step A31 in FIG. 6), the step in FIG. The process from A32 to Step A35 was repeated.

  This is based on the premise that the left BD sensor 13, the right BD sensor 14, or the one-side BD sensor 21 can always properly detect the laser beam. However, after shifting to steady APC, the optical axis shift of the left BD sensor 13, the right BD sensor 14, or the one-side BD sensor 21 may temporarily occur. In this case, although the laser beam is emitted at an appropriate timing, the left BD sensor 13, the right BD sensor 14, or the one-side BD sensor 21 cannot detect the laser beam.

  Then, even if the temporary optical axis deviation returns to normal, steady APC cannot be performed at an appropriate timing. As a result, when the optical axis shift occurs temporarily, it is necessary to execute the initial APC again.

  This point will be described by comparing the timing chart of FIG. 5 with the timing chart of FIG.

  As shown in FIG. 5, in this example, the left BD sensor 13 first detects the laser beam twice, that is, detection during B-direction scanning and detection during A-direction scanning. However, it is assumed that a temporary optical axis shift occurs in the left BD sensor 13 after the laser beam is detected once during the B-direction scanning. In this case, as shown in FIG. 13, it is impossible to detect the laser beam at the time of scanning in the A direction, which should be detected by the left BD sensor 13.

  However, the circuit corresponding to nAPC2, which is a circuit corresponding to the detection of the laser beam at the time of scanning in the A direction by the left BD sensor 13, has passed one cycle of reciprocating scanning from the input of the detection signal in the previous process. Therefore, it waits for detection of the laser beam. When the right side BD sensor 14 detects the laser beam during scanning in the A direction, the circuit corresponding to the nAPC 2 uses the timing at which the right side BD sensor 14 detects the laser beam as a reference. That is, the circuit corresponding to nAPC2 and the circuit corresponding to nAPC3 are based on the same timing.

  When the circuit corresponding to nAPC2 and the circuit corresponding to nAPC3 are close to the time elapsed for one cycle of reciprocating scanning from this reference (Yes in step A31 in FIG. 6), the process from step A32 to step A35 in FIG. Processing will be performed.

In this case, even if the temporary optical axis shift of the left BD sensor 13 thereafter returns to normal, the circuit corresponding to nAPC2 is essentially the timing at which the circuit corresponding to nAPC2 should perform the processing of FIG. Do not process. Specifically, the process of FIG. 6 is not performed at the timing when the left BD sensor 13 detects the laser beam during the A-direction scanning.
Therefore, the laser beam is not emitted (step A32 in FIG. 6) at the timing at which the left BD sensor 13 should detect the laser beam when scanning in the A direction.

  Accordingly, as described above, after that, even if the temporary optical axis shift returns to normal, steady APC cannot be performed at an appropriate timing. As a result, when the optical axis shift occurs temporarily, it is necessary to execute the initial APC again.

  Therefore, in the present embodiment, even when such a temporary optical axis shift occurs, steady APC can be appropriately continued without performing initial APC again. The processing for this will be described with reference to the flowchart of FIG. 14 and the sequence diagram of FIG.

  Here, Step A32 to Step A35 in FIG. 14 are the same as the processing of the step having the same name described with reference to FIG. Hereinafter, a case where a temporary optical axis shift occurs in the left BD sensor 13 will be described as an example. That is, as described above with reference to FIG. 13, after the left BD sensor 13 detects the laser beam once during the B-direction scanning, a temporary optical axis shift occurs in the left BD sensor 13, and the left BD sensor 13. The case where the laser beam cannot be detected at the time of scanning in the A direction, which is supposed to be detected in FIG. Therefore, the processing relating to the detection of the laser light during the A-direction scanning is an object of explanation.

  However, this is merely an example for explanation, and the present embodiment can also cope with a case where an optical axis shift occurs at another timing.

  First, it waits until the period of any one of the first period to the fourth period is close to the lapse of time for one period of reciprocating scanning (No in step A61). Here, in each of the above-described embodiments, in order to perform the determination in step A31, only the description is made that the circuits corresponding to each of nAPC1 to nAPC4 count until the time for one cycle of the reciprocating scan is close. However, in the present embodiment, the count will be described in more detail.

  Specifically, the circuits corresponding to each of nAPC1 to nAPC4 perform counting by setting a timer from the previous detection signal input and increasing the count value of the timer as time elapses. If the timer count value exceeds the timer set value (that is, if each timer count value is greater than the timer set value as shown in the figure), the time elapses for one cycle of the reciprocating scan. (Yes in step A61).

  Here, the timer set value is set as a value smaller than the timer count value counted until the time for one cycle of the reciprocating scan elapses. The smaller value is determined according to the environment in which the present embodiment is implemented.

  The circuit corresponding to nAPC2, which is the circuit for the second period to be described this time, is close to the lapse of one cycle of the reciprocating scan from the previous input of the detection signal, and “each timer count value> timer If the relationship of “set value” is established (Yes in step A61), the signal output to the circuit corresponding to nAPC is set to the low level.

  Then, the signal output from the circuit corresponding to nAPC also becomes a low level triggered by the change in the signal. Then, the APC control unit 20 controls the control voltage of the LD unit 11 to cause the LD unit 11 to emit laser light (step A32). That is, the laser beam is emitted just before the timing at which the left BD sensor 13 will detect the laser beam during the B-direction scanning.

Next, the APC control unit 20 makes the output current of the photodiode constant based on the output current of the photodiode in the LD unit 11 as described above, that is, the output of the laser light emitted from the LD unit 11. The drive current of the LD unit 11 is adjusted so that becomes constant (step A33).
Next, it is determined whether the laser beam being emitted is detected by the left BD sensor 13 (step A34).

  Here, if there is no problem such as optical axis misalignment in the left BD sensor 13, laser light is detected (Yes in step A34) and the process proceeds to step A35.

  In step A35, the APC controller 20 controls the drive current to cause the LD unit 11 to finish emitting laser light (step A35). The circuit corresponding to nAPC2 that has output a low level signal in step A31 again counts the time for one cycle of reciprocating scanning.

  Then, the process returns to step A31, and waits until the time for one cycle of the reciprocating scan approaches in another cycle (No in step A31), and the subsequent processing is repeated.

However, in this example, as described above, since a temporary optical axis shift occurs in the left BD sensor 13, the laser beam is not detected, and the timing at which the laser beam is originally detected and Yes in step A34. Even in this case, No remains in step A34. If the determination in step A34 is repeated as it is, the laser beam is detected at the timing corresponding to nAPC3 as described above with reference to FIG.
Therefore, in the present embodiment, processing from step A62 to step A64 is added.

  Specifically, in FIG. 6, when the laser beam is not detected as a result of the determination (No in Step A34), the standby is performed as it is, and the determination is repeated. However, in this embodiment, when the laser beam is not detected as a result of the determination (No in Step A34), the process proceeds to Step A62.

  In Step A62, it is determined whether or not the timer count value has reached an upper limit value. Here, the timer upper limit value is set as a value larger than the timer count value counted until the time corresponding to one cycle of the reciprocating scan elapses from the previous detection signal input. How large the value is determined is determined according to the environment in which this embodiment is implemented. If the timer count value is not the upper limit value (No in step A62), the process returns to step A34 again and the process is repeated.

  However, as described above, since a temporary optical axis misalignment occurs in the left BD sensor 13, the laser beam is not detected, and even when the laser beam is originally detected and the timing becomes Yes in step A34, It remains No in step A34.

  Then, as time elapses, the count value of the timer to be processed in step A61 or step A62 becomes the upper limit value (Yes in step A62), and the process proceeds to step A63.

  Then, the circuit corresponding to nAPC2 sets the signal output to the circuit corresponding to nAPC to a high level. Then, the signal output from the circuit corresponding to nAPC also becomes a high level triggered by the change in the signal. Then, the APC control unit 20 causes the LD unit 11 to finish emitting laser light by controlling the control voltage of the LD unit 11 (step A63).

  Then, the count value of the timer to be processed in step A61 or step A62 is reset. After resetting, the process returns to step A61 and continues.

  Then, if the temporary optical axis shift returns to normal on the left BD sensor 13 in the course of this processing, the result of step A34 is Yes, and steady APC can be continuously performed at an appropriate timing.

  This point will be described with reference to the timing chart of FIG. As described above, if a temporary optical axis deviation occurs in the left BD sensor 13, undetected occurs, and the laser light is not detected even when the time for which the laser light is originally detected has elapsed.

  However, before the laser beam is detected at the timing corresponding to nAPC3, the timer count value becomes the upper limit value, so that the signal output by the circuit corresponding to nAPC is also at the high level. Thereby, the emission of the laser light ends.

In addition, since the count value is reset by another timer and processing is performed using the reset timer, the laser beam is emitted at an appropriate timing corresponding to the next nAPC2. If the temporary optical axis shift returns to the left BD sensor 13, the laser beam emitted at this appropriate timing can be detected. Thereby, the problem described with reference to FIG. 13 can be solved.
<Seventh Embodiment>

Next, a seventh embodiment will be described. The seventh embodiment is an image forming apparatus 1000 on which any one of the optical scanning units according to the six embodiments described above is mounted. In the seventh embodiment, an electrostatic latent image is formed by the light beam emitted from any of the optical scanning units of the six embodiments described above.
The overall configuration of the image forming apparatus 1000 according to the seventh embodiment will be described with reference to FIG.

  As illustrated in FIG. 16, the image forming apparatus 1000 includes a sheet feeding unit 51 that feeds sheets, a manual feeding unit 61 that can manually feed sheets, and a sheet feeding unit 51 or a manual feeding unit 61. Are provided with an image forming unit 31 that forms an image on the sheet fed by the above, a sheet discharge unit 80 that discharges the sheet on which the image is formed to the outside of the apparatus, and a control unit 90 that controls these.

  Further, a front door (not shown) that can be opened inside is provided on the front surface of the image forming apparatus 1000, and the above-described image forming unit 31 and the like disposed inside by opening the front door. Can be exposed. Further, an operation panel for performing various operations is provided above the front door. The operation panel includes a display unit for displaying various information and an operation unit having various input keys. ing. The display unit and the operation unit may be integrated in the form of a touch panel or the like.

  The sheet feeding unit 51 includes a feeding sheet stacking unit 52 that stacks and accommodates sheets, and a separation feeding unit 53 that separates and feeds the sheets stacked on the feeding sheet stacking unit 52 one by one. . The feeding sheet stacking unit 52 includes an intermediate plate 55 that rotates about a rotation shaft 54. The intermediate plate 55 is biased upward, and rotates when the sheet is fed. The sheet is lifted upward (state of two-dot chain line shown in FIG. 16). The separation feeding unit 53 includes a pickup roller 56 that feeds the sheet lifted by the intermediate plate 55, and a separation pad 57 that is in pressure contact with the pickup roller 56.

  The manual feeding unit 61 includes a manual tray 62 on which sheets can be stacked, and a separation feeding unit 63 that can feed the sheets stacked on the manual tray 62 while separating the sheets one by one. The manual feed tray 62 is rotatably supported by the image forming apparatus casing 1001. When manually feeding the sheet, the manual feed tray 62 can be rotated to be stacked (the state of the two-dot chain line shown in FIG. 16). ). The separation feeding unit 63 includes a feeding roller 64 that feeds the sheets stacked on the manual feed tray 62, and a separation pad 65 that is in pressure contact with the feeding roller 64.

  The image forming unit 31 includes four process cartridges (image forming units) 30B, 30C, 30M, and 30Y that form black (B), cyan (C), magenta (M), and yellow (Y) images. The optical scanning device 101 that exposes the surfaces of the photosensitive drums 300B, 300C, 300M, and 300Y included therein, and the transfer unit 33 that transfers the toner images formed on the surfaces of the photosensitive drums 300B, 300C, 300M, and 300Y to a sheet. And a fixing unit 34 for fixing the unfixed toner image transferred to the sheet. Note that alphabets (B, C, M, and Y) added to the end of the reference numerals indicate the colors of the respective toners (black, cyan, magenta, and yellow). The photosensitive drums 300B, 300C, 300M, and 300Y are portions corresponding to the photosensitive drum 300 described with reference to FIG.

  The optical scanning device 101 includes optical scanning units 100B, 100C, 100M, and 100Y corresponding to the photosensitive drums 300B, 300C, 300M, and 300Y, respectively. Here, each of the optical scanning units 100B, 100C, 100M and 100Y corresponds to the optical scanning unit 100 described above. In addition, each of the optical scanning units 100B, 100C, 100M, and 100Y may be replaced with the optical scanning unit 200 and the optical scanning unit 101 described above. That is, the optical scanning units 100B and 100C in any of the first embodiment, the second embodiment, the third embodiment, the fourth embodiment, the fifth embodiment, and the sixth embodiment described above. 100M and 100Y may be realized.

  The optical scanning units 100B, 100C, 100M, and 100Y include the LD unit 11 that emits laser light as described above, the MEMS mirror 12 that guides the laser light to the photosensitive drums 300B, 300C, 300M, and 300Y, and the like. The optical scanning units 100B, 100C, 100M, and 100Y perform exposure scanning in two directions along the axial direction (main scanning direction) with the laser light on the surfaces of the photosensitive drums 300B, 300C, 300M, and 300Y of the image forming unit 31. Thus, each electrostatic latent image is formed. In FIG. 16, illustration of the arrangement positions of the left BD sensor 13 and the right BD sensor 14 is omitted. Also, a person skilled in the art will know processing for forming respective electrostatic latent images by exposing and scanning the surfaces of the photosensitive drums 300B, 300C, 300M and 300Y in both directions along the axial direction (main scanning direction). Since this is well known to those skilled in the art, the description of this process is omitted.

  The process cartridges 30 </ b> B to 30 </ b> Y are configured to be detachable from the image forming apparatus housing 1001 and can be replaced. The process cartridge 30B includes a photosensitive drum (image carrier) 300B on which a monochrome toner image is formed, a charging device 301B that charges the photosensitive drum 300B, and a static image formed on the photosensitive drum 300B by the optical scanning device 200. A developing device 302B that develops the electrostatic latent image with black toner, and a cleaner unit 303B that removes residual toner remaining on the surface of the photosensitive drum 300B even after the toner image obtained by development is transferred to the intermediate transfer belt. I have. The same applies to the process cartridges 30C, 30M, and 30Y.

  The developing device 302B includes a developing device main body 304B that develops the electrostatic latent image with black toner, and a toner cartridge 305B that supplies black toner to the developing device main body 304B. The toner cartridge 305B is configured to be detachable from the developing device main body 304B. When the stored black toner runs out, the toner cartridge 305B can be removed from the developing device main body 304B and replaced. The same applies to the developing device 302C, the developing device 302M, and the developing device 302Y.

  In FIG. 16, an alphabet such as B, C, M, and Y is added at the end of the code to distinguish the portion corresponding to any color. However, since the basic configurations of the optical scanning unit 100B, the optical scanning unit 100C, the optical scanning unit 100M, and the optical scanning unit 100Y are the same, in the description of each embodiment described above, the optical scanning unit 100 and the optical scanning unit 200 are the same. We explained without adding alphabet. Similarly, the photosensitive drum 300 and the like have been described without adding an alphabet in the description of each embodiment described above.

  The seven embodiments have been described above. The optical scanning unit of each of the embodiments described above and the image forming apparatus including the same can be realized by hardware, software, or a combination thereof. The optical scanning control method performed by the image forming apparatus and the optical scanning unit included in the image forming apparatus can also be realized by hardware, software, or a combination thereof. Here, “realized by software” means realized by a computer reading and executing a program.

  The program may be stored using various types of non-transitory computer readable media and supplied to the computer. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer readable media include magnetic recording media (for example, flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (for example, magneto-optical disks), CD-ROMs (Read Only Memory), CD- R, CD-R / W, and semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (random access memory)).

  Moreover, although the above-described embodiment is a preferred embodiment of the present invention, the scope of the present invention is not limited only to the above-described embodiment, and various modifications are made without departing from the gist of the present invention. Implementation in the form is possible.

  For example, some or all of the embodiments may be combined without departing from the scope of the present invention. For example, the fifth embodiment may be realized by modifying the optical scanning unit 200 of the second embodiment. Further, the sixth embodiment may be realized by the optical scanning unit 200 of the second embodiment. Furthermore, the processes of the third embodiment and the fourth embodiment may be added to these embodiments.

  The present invention is suitable for controlling an optical scanning unit mounted on, for example, a multifunction machine.

11 LD unit 12 MEMS mirror 13 Left BD sensor 14 Right BD sensor 15 Timekeeping unit 16 Comparison unit 17 Storage unit 18 PWM control unit 19 MEMS drive unit 20 APC control unit 21 BD sensors 30B, 30C, 30M, 30Y Process cartridge 31 Image formation Section 33 Transfer section Fixing section 51 Sheet feeding section 52 Sheet feeding section 53 Separation feeding section 54 Rotating shaft 55 Middle plate 56 Pickup roller 57 Separation pad 61 Manual feeding section 62 Manual tray 63 Separating feeding section 64 Feed roller 65 Separation pad 80 Sheet discharge unit 90 Control units 100, 101, 200 Optical scanning units 300, 300B, 300C, 300M, 300Y Photosensitive drums 301B, 301C, 301M, 301Y Charging devices 302B, 302C, 302M, 302Y Development Device 303 , 303C, 303M, 303Y cleaner unit 304B, 304C, 304M, 304Y developing device main body (developing unit)
1000 Image forming apparatus 1001 Copier casing

Claims (12)

A light beam emitting means for emitting a light beam;
A scanning body that reciprocally scans the light beam by reflecting the light beam while performing a scanning motion;
A plurality of light detecting means arranged at different positions within a reciprocating scanning range of the light beam;
The light beam emitting means continues to emit the light beam, and when the light beams are detected by each of the plurality of light detecting means, the light beam emitting means ends the continuation of the light beam emission, and Control means for starting predetermined processing based on a plurality of time points when the light beam is detected by each of the light detection means;
An optical scanning device comprising:   A scanning object that is scanned by the light beam exists within the reciprocating scanning range of the light beam, and the scanning object is not scanned by the light beam at both ends of the reciprocating scanning range of the light beam. 2. The optical scanning device according to claim 1, wherein any one of the plurality of light detection units is arranged in each of the ranges existing at both ends.   Each of the plurality of light detection means detects the light beam accompanying the movement in the first scanning direction in the reciprocating scanning and moves in the second scanning direction opposite to the first scanning direction. In response to the detection of both of the detection of the light beam, the continuation of the emission of the light beam is terminated, and a plurality of time points when the light beam is detected by each of the plurality of light detection means are used as references. The optical scanning apparatus according to claim 1, wherein the predetermined processing is started. As one of the predetermined processes,
The light beam emitting means emits the light beam at predetermined intervals based on a plurality of time points when the light beams are detected by the plurality of light detecting means, respectively, and based on the light quantity of the emitted light beam. 4. The optical scanning device according to claim 1, wherein a process of adjusting an emitted light amount of the light beam of the light beam emitting means is performed. 5. As one of the predetermined processes,
The light beam emitting means emits the light beam at predetermined intervals based on a plurality of time points when the light beams are detected by the plurality of light detecting means, respectively, and the emitted light beams are used as the plurality of light beams. 5. The optical scanning device according to claim 1, wherein a process for controlling a scanning motion of the scanning body is performed based on a time interval detected by each of the detection units. 6.   2. The predetermined process is started on the condition that the scanning motion of the scanning body is in a steady state by adjusting a driving frequency for driving the scanning body and waiting for a predetermined time. 6. The optical scanning device according to any one of items 1 to 5. As one of the predetermined processes,
The light beam emitting means emits the light beam at predetermined intervals based on a plurality of time points when the light beams are detected by the plurality of light detecting means, respectively, and the emitted light beams are used as the plurality of light beams. When each of the detection means repeats detection,
When the predetermined interval elapses, the count value of a timer for counting the time until the predetermined interval arrives is reset, and counting of the time until the predetermined interval arrives is continued. The optical scanning device according to any one of claims 1 to 6. A light beam emitting means for emitting a light beam;
A scanning body that reciprocally scans the light beam by reflecting the light beam while performing a scanning motion;
One photodetecting means disposed within a reciprocating scanning range of the light beam;
The light beam emitting means continues to emit the light beam, and when the light detecting means detects the light beam, the light beam emitting means ends the emission of the light beam, and the light detecting means Control means for starting a predetermined process based on the time point when the light beam is detected;
An optical scanning device comprising:   The light detecting means detects the light beam accompanying the movement in the first scanning direction in the reciprocating scanning, and the light beam accompanying the movement in the second scanning direction opposite to the first scanning direction. In response to the detection of both detections, the continuation of emission of the light beam is terminated, and predetermined processing based on a plurality of time points when the light beam is detected by the light detection means is started. The optical scanning device according to claim 8.   10. The optical scanning device according to claim 1, wherein the scanning body driving device is a micro electro mechanical system (MEMS). An image forming apparatus comprising the optical scanning device according to any one of claims 1 to 10,
An image forming apparatus, wherein an electrostatic latent image is formed by the light beam emitted by the light beam emitting means. A light beam emitting means for emitting a light beam;
A scanning body that reciprocally scans the light beam by reflecting the light beam while performing a scanning motion;
A plurality of light detecting means arranged at different positions within a reciprocating scanning range of the light beam;
An optical scanning control method performed by an optical scanning device comprising:
The light beam emitting means continues to emit the light beam, and when the light beams are detected by each of the plurality of light detecting means, the light beam emitting means ends the continuation of the light beam emission, and An optical scanning control method, comprising: starting predetermined processing based on a plurality of time points when the light beam is detected by each of the light detection means.

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