JP2007079291A - Optical writing controller, optical writing apparatus, image forming apparatus, and optical writing control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect an correction amount for deviation of main scanning position after the assembly of LDs and LDAs/the adjustment of vertical sub scanning pitch, and to detect the correction amount for deviation of main scanning position due to the wavelength difference between the LDs and the LDAs. <P>SOLUTION: An optical writing controller is provided with: a plurality of independent laser diodes 1 which are modulated and controlled according to a picture signal; a photoreceptor 3 irradiated with laser light emitted from the laser diode 1; a front end synchronization detecting sensor 4 and a rear end synchronization detecting sensor 5 which are arranged on the front end side and the rear end side with respect to the main scanning direction of the photoreceptor 3; and a controlling part 9 which counts the interval between the optical detections of the front end and rear end synchronization detecting sensors 4 and 5 and detects the correction amount for deviation in the main scanning direction on the basis of the counted value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical writing control device for writing an image on an image carrier by exposure with a light beam emitted from a laser diode, an optical writing device provided with the optical writing control device, and a digital copy provided with the optical writing device. The present invention relates to an image forming apparatus such as an image forming apparatus, a digital multi-function peripheral, a laser printer, and a facsimile, and an optical writing control method implemented by these.

  As this type of technology, for example, a digital copying machine and an MFP (digital multifunction peripheral) using a laser diode array (hereinafter also referred to as LDA) are known. A plurality of laser diodes (hereinafter also referred to as “LDs”) are arranged at almost constant intervals in the LDA, but variations in mounting cannot be eliminated. For example, as shown in FIG. 19, an inclination θ is generated at the time of assembling for each aircraft, and this inclination θ is also an example of physical variation. Such variation is inevitably generated in the assembly process. In addition, adjusting the beam interval with the dedicated jig to match the resolution in the sub-scanning direction also causes the inclination θ.

  FIG. 20 is an explanatory diagram showing the inclinations of two LDAs (LDA0 and LDA1) when the sub-scanning beam interval is adjusted to 600 dpi. If all the LDs in the LDA are caused to emit light at the same time to expose the photoreceptor, the main scanning position shift occurs due to the inclination of the LDA, and the image quality deteriorates. Furthermore, due to variations in characteristics such that a wavelength difference occurs between LDAs due to variations in the manufacturing process, a shift occurs in the main scanning direction when a plurality of LDAs are used. Patent Document 1 discloses a technique for detecting the amount of correction using the dedicated jig described above and feeding back to the writing control apparatus in order to correct these positional deviations.

Further, not only the physical (mechanical) variation but also variation due to temperature change occurs. For example, Patent Document 2 discloses a technique for suppressing a shift in scanning start timing of a plurality of beams accompanying a temperature change.
JP 2001-228418 A JP 2002-122799 A

  In Patent Document 1, an optical writing apparatus using a plurality of LDAs is configured to correct misalignment using a dedicated jig. However, the use of this dedicated jig also causes variations. Is as described above. Further, Patent Document 2 corrects a shift in scanning start timing of a plurality of beams due to a temperature change, but does not correct a shift between LDAs, and the problem of the shift is solved. I don't mean.

  The present invention has been made in view of such a background, and an object of the present invention is to perform main scanning after assembly of LD and LDA / adjustment of sub-scanning pitch without using a dedicated jig or changing the conventional configuration. The main purpose is to detect a main-scanning positional deviation correction amount due to a positional deviation correction amount or a wavelength difference between the LD and the LDA.

  Another object is to make it possible to correct the shift amount based on the detected correction amount.

  In order to achieve the object, the first means includes a plurality of independent laser diodes that are modulated and controlled according to an image signal, an image carrier that is irradiated with laser light emitted from the laser diode, and the image Between the photoelectric conversion elements arranged on the front end side and the rear end side with respect to the main scanning direction of the carrier, detecting the laser beam and outputting a synchronization signal, and the photoelectric conversion elements on the front end side and the rear end side An optical writing control device comprising: a counting unit that counts a light detection interval; and a detecting unit that detects a shift correction amount in the main scanning direction based on a count value counted by the counting unit.

  The second means is characterized in that, instead of the plurality of independent laser diodes in the first means, a laser diode array in which the laser diodes are arranged in a plurality of arrays is used.

  The third means detects the inclination of each laser diode array in the main scanning direction based on the count value in the second means, and physically detects the laser diodes built in each of the laser diode arrays. A main scanning direction deviation correction amount due to a factor is detected, and a main scanning direction deviation correction amount of a built-in laser diode that is most adjacent between different laser diode arrays is detected.

  The fourth means is characterized in that, in any one of the first to third means, the deviation correction amount is generated due to a physical factor between laser diodes different from each other.

  The fifth means is characterized in that, in the first or second means, the wavelength difference between laser diodes having different shift correction amounts is a factor.

  The sixth means includes a laser diode array in which a plurality of laser diodes that are modulated and controlled according to an image signal are arranged in an array, and an image carrier that is irradiated with laser light emitted from the laser diodes of the laser diode array A photoelectric conversion element that is disposed on the distal end side with respect to the main scanning direction of the image carrier and detects the laser beam and outputs a synchronization signal; and light detection detected by the photoelectric conversion element on the distal end side A counting unit that counts the interval, and a tilt in the main scanning direction of the laser diode array is detected based on the count value counted by the counting unit, and a deviation in the main scanning direction of the laser diode built in the laser diode array is corrected. An optical writing control device including detection means for detecting the quantity is characterized.

  The seventh means is characterized in that, in the first to sixth means, a correction means for correcting a shift amount in the main scanning direction based on the correction amount detected by the detection means.

  The eighth means is characterized in that the optical writing apparatus includes the optical writing control apparatus according to any one of the first to seventh means.

  A ninth means is characterized in that the image forming apparatus includes the optical writing device according to the eighth means.

  The tenth means scans the image carrier with laser light emitted from a plurality of independent laser diodes modulated and controlled in accordance with the image signal in the main scanning direction, and the scanned laser light is the image. Photoelectric conversion elements on the front end side and the rear end side, which are respectively arranged on the front end side and the rear end side with respect to the main scanning direction of the carrier and detected by the photoelectric conversion elements that detect the laser beam and output a synchronization signal The optical writing control method is characterized in that a light detection interval is counted, and a deviation correction amount in the main scanning direction is detected based on the counted value.

  An eleventh means is a laser diode array in which the laser diodes are arranged in a plurality of arrays instead of the plurality of independent laser diodes in the tenth means, and each of the laser diode arrays is based on the count value. The inclination in the main scanning direction is detected, and the main scanning direction deviation correction amount of the most adjacent built-in laser diode between different laser diode arrays is detected.

  The twelfth means scans the image carrier in the main scanning direction with the laser light emitted from the laser diode of the laser diode array in which a plurality of laser diodes that are modulated and controlled according to the image signal are arranged in an array. The scanned laser beam is arranged on the tip side with respect to the main scanning direction of the image carrier, and is detected by a photoelectric conversion element that detects the laser beam and outputs a synchronization signal. The light detection interval detected by the conversion element is counted, the inclination of the laser diode array in the main scanning direction is detected based on the counted value, and the main scanning direction of the laser diode incorporated in the laser diode array An optical writing control method for detecting a shift correction amount is characterized.

  A thirteenth means is characterized in that, in any one of the tenth to twelfth means, the deviation amount in the main scanning direction is corrected based on the detected correction amount.

  In the embodiment described later, the laser diode is in LD0 to LD7, the image carrier is in the photosensitive member 3, the photoelectric conversion element is in the leading edge synchronization detecting sensor 4 and the trailing edge synchronization detecting sensor 5, and the counting means, detecting means, and correction. The means corresponds to the controller 9, and the laser diode array corresponds to LDA0 and LDA1, respectively.

  According to the present invention, the light detection interval between the photoelectric conversion elements on the front end side and the rear end side is counted, and the deviation correction amount in the main scanning direction is detected based on the counted value, so a dedicated jig is used. Without changing the conventional configuration, the main scanning position deviation correction amount due to physical factors that occur when assembling the laser diode and laser diode array and adjusting the resolution in the sub-scanning direction, and variations in the characteristics of LD and LDA manufacturing A misregistration correction amount in the main scanning direction due to the generated wavelength difference can be detected. In addition, since the correction amount can be detected, the shift amount can be corrected based on the detected correction amount.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic diagram showing an optical writing apparatus that forms an electrostatic latent image on a photoreceptor using an LD according to the present embodiment. Actually, a plurality of LDs are used, and the laser light emitted from each LD 1 is reflected by the polygon mirror 2 to form an electrostatic latent image on the photosensitive member 3. In addition, a front-end synchronization detection sensor 4 and a rear-end synchronization detection sensor 5 each including a photoelectric conversion element for detecting the synchronization timing of LD light emission are disposed at the front and rear end positions in the main scanning direction. The polygon mirror 2 is rotationally driven at a high speed by a polygon motor 6, and the polygon motor 6 is driven and controlled by a motor driver 7. The laser diode is controlled in light emission by modulating the input signal by the laser driving circuit 8. Detection outputs of the front end synchronization sensor 4 and the rear end synchronization detection sensor 5 are input to the control unit 9, and control signals are output from the control unit 9 to the laser drive circuit 8 and the motor driver 7, respectively.

  The controller 9 includes a microcomputer including a CPU (not shown), and uses an RAM (not shown) as a work area, and includes an LD writing amount D process described later according to a program stored in a ROM (not shown). Perform the processing required for In addition, an internal counter that counts a difference in detection timing between the front-end synchronization detection sensor 5 and the rear-end synchronization detection sensor 5 is provided. Such an optical writing device is a device that is a premise of the following description.

  FIG. 2 is a timing chart showing timings of detection of correction amounts of deviation in the main scanning direction of LD0 to LD1, LD1 to LD2, and LD2 to LD3. Based on the detection timing of the leading edge synchronization detection sensor 4 (hereinafter also referred to as leading edge synchronization detection timing) using LD0 as a reference LD, only LD0 emits light to detect timing, and the trailing edge synchronization detection sensor 5 detects LD0, LD1, LD2, and LD3. The light is emitted by switching sequentially. Thus, the count values D1, D2, D3, D4 from the leading edge synchronization of the LD0 reference T1 to the trailing edge synchronizations T2, T3, T4, T5 of LD1 to LD3 (D1 = LD0 to LD0, D2 = LD0 to LD1, LD3, D3 = LD0 to LD2, D4 = LD0 to LD3) can be obtained by the internal counter. Thus, for example, when LD1, LD2, and LD3 are arranged in order with LD0 at the leading end as shown in FIG. 2, the relationship of D1 <D2 <D3 <D4 holds, and the amount of correction for positional deviation in the main scanning direction of each LD. Can be detected by subtracting D1 to D4.

  FIG. 3 is a timing chart showing detection timings of the leading edge synchronization detection sensor 4 and the trailing edge synchronization detection sensor 5 (hereinafter also referred to as trailing edge synchronization detection timing) when the LD0 is shifted. As shown in the figure, for example, when LD0 is located between LD1 and LD2, D1> D2 and D2-D1 becomes negative, so LD1 is shifted to the left by | D2-D1 | from LD0. If the amount of correction correction | D2-D1 | between LD0 and LD1 is fed back to the control so that LD1 emits light slowly with respect to LD0, light emission occurs at the timing shown in FIG. Can be made.

  FIG. 4 is a timing chart showing the timing when the leading end and trailing end synchronization timings are detected by the same LD. As shown in FIG. 4, when the leading end and trailing end synchronization timings are detected by the same LD, the count values D1 to D4 can be obtained. If the wavelengths of LD0 to LD4 match, the count values D1 to D4 are all equal, but in reality, a wavelength difference is caused by a difference in characteristics due to variations in manufacturing of the LD. Although the positional deviation in the main scanning direction due to this wavelength difference occurs, the positional deviation correction amount in the main scanning direction due to the wavelength difference of LD0 to LD3 can be detected by comparing the count values D1 to D4.

FIG. 5 is a timing chart showing an example of the leading edge and trailing edge detection timing when one LDA containing four LDs is used. As shown in the figure, when one LDA containing four LDs is used, the wavelength difference can be ignored because the LD arrangement interval in the same LDA is almost constant and the manufacturing process is the same. Because of the level, the position shift of the built-in LD in the main scanning method due to the inclination of the LDA becomes a problem. This positional deviation correction amount is obtained by the following procedure, for example. That is, the LD (eg, LD0) at the end serving as a reference when detecting the leading end synchronization detection timing emits light, and the LD (eg, LD0) used as the reference when detecting the trailing end synchronization detection timing and a position opposite to the reference LD The counter values D1 and D2 are obtained by emitting the respective LDs (for example, LD4) at the end of each of them. Since the LD interval in the same LDA is almost constant, the positional deviation correction amount in the main scanning direction is | D1-D2 | / 3.
Can be obtained. In the example of the figure, D1 <D2, but it can be seen that when D1> D2, the LD at the end opposite to the reference LD is in a reverse positional relationship. When D1 = D2, all the LDs are in the main scanning direction. It will be complete.

  6 to 13 are diagrams showing timings for detecting the leading and trailing edge synchronization when a plurality of LDAs are used. Here, an example in which two LDAs incorporating two LDs are used is shown. In the case where a plurality of LDAs are used, the meaning of the counter value differs depending on the relationship of the position of the reference LD in each LDA. Therefore, the sequence for obtaining the counter value is determined, and the obtained counter value is determined. From this relationship, it is possible to determine what the LDA inclination relationship is. For example, the following sequence will be described.

≪Count value calculation sequence≫
1) D1 measurement ⇒ leading edge synchronization: LDA1 reference LD101, trailing edge synchronization: LDA1 reference LD101 ′
2) D2 measurement ⇒ leading edge synchronization: LDA1 reference LD101, trailing edge synchronization: LD102 ′ at the end that is not LDA1 reference
3) D3 measurement ⇒ leading edge synchronization: LDA0 reference LD103, trailing edge synchronization: LDA0 reference LD103 ′
4) D4 measurement ⇒ leading edge synchronization: LDA0 standard LD103, trailing edge synchronization: LD104 ′ at the end not based on LDA0
5) D5 measurement ⇒ leading edge synchronization: LDA0 reference LD103, trailing edge synchronization: LDA1 reference LD101 ′
By unifying this sequence, the relationship between the counter values D1 to D4 is obtained. As shown in FIGS. 6 to 13, the positional deviation correction amount in the main scanning direction of each LD in the LDA and the position of the LD in the LDA closest to each other are obtained. The deviation correction amount D can be obtained.

That is, corresponding to the above 1) to 5),
In the case of 1), the count value is D1
In the case of 2), the count value is D2.
In the case of 3), the count value is D3
In the case of 4), the count value is D4
In the case of 5), the count value is D5
In the example of FIG. 6, D1> D2, D3> D4,
LD interval in LDA0 = | D3-D4 | / (number of LDs−1)
LD interval in LDA1 = | D1-D2 | / (number of LDs−1)
LDA deviation amount D = D5-D3- (| D1-D2 |)
It becomes.

In the example of FIG. 7, D1> D2, D3 <D4,
LD interval in LDA0 = | D3-D4 | / (number of LDs−1)
LD interval in LDA1 = | D1-D2 | / (number of LDs−1)
LDA deviation amount D = D5-D4- (| D1-D2 |)
It becomes.

In the example of FIG. 8, D1 <D2, D3> D4,
LD interval in LDA0 = | D3-D4 | / (number of LDs−1)
LD interval in LDA1 = | D1-D2 | / (number of LDs−1)
LDA deviation amount D = D5-D3
It becomes.

In the example of FIG. 9, D1 <D2, D3 <D4,
LD interval in LDA0 = | D3-D4 | / (number of LDs−1)
LD interval in LDA1 = | D1-D2 | / (number of LDs−1)
LDA deviation amount D = D5-D4
It becomes.

In the example of FIG. 10, D1 = D2, D3> D4,
LD interval in LDA0 = | D3-D4 | / (number of LDs−1)
LD interval in LDA1 = 0
LDA deviation amount D = D5-D3
It becomes.

In the example of FIG. 11, D1 = D2, D3 <D4,
LD interval in LDA0 = | D3-D4 | / (number of LDs−1)
LD interval in LDA1 = 0
LDA deviation amount D = D5-D4
It becomes.

In the example of FIG. 12, D1 = D2, D3 = D4,
LD interval in LDA0 = 0
LD interval in LDA1 = 0
LDA deviation amount D = D5-D3
It becomes.

  Further, as shown in FIG. 13, by calculating the counter value of the leading / rear end synchronization detection timing based on the reference LDs 101 and 103 of each LDA, the amount of misregistration correction in the main scanning direction caused by the wavelength difference due to the characteristic variation between the LDAs can be obtained. Can be sought.

  Further, when a plurality of LDAs are used, it is only necessary to detect the shift amount D of the LD in the LDA that is closest to the slope of each LDA. Therefore, if the count value calculation sequence is determined in the same manner as described above, the synchronization detection can be performed. Therefore, the photoelectric conversion element can be provided only at the tip portion. In addition, even if it has a photoelectric conversion element for a synchronous detection at the front-end | tip and a rear end on a structure, it is possible to use this invention.

  FIG. 14 to FIG. 17 are diagrams showing an example in which two LDAs having four LDs are used. In this case, the sequence is as follows.

≪Count value calculation sequence≫
6) D1 measurement => LDA0: reference LD0 (endmost) 201, LDA1: reference LD4 (201 ′)
7) D2 measurement ⇒ LDA0: reference LD0 (most end) 201, LDA1: LD7 (LD204 ′ at the end that is not the reference)
8) D3 measurement⇒LDA0: LD3 (non-reference end LD204), LDA1: reference LD4 (201 ′)
By unifying into this sequence, the relationship between the counter values D1 to D4 is obtained. As shown in FIGS. 14 to 17, the positional deviation correction amount in the main scanning direction of each LD in the LDA and the position of the LD in the LDA closest to each other are obtained. The deviation correction amount D can be obtained.

That is, corresponding to the above 6) to 8),
In the case of 6), the count value is D1
In the case of 7), the count value is D2.
In the case of 8), the count value is D3
In the example of FIG. 14, D3 <D1 <D2 and
LD interval in LDA0 = | D1-D3 | / (number of LDs−1)
LD interval in LDA1 = | D1-D2 | / (number of LDs−2)
LDA deviation amount D = D3
It becomes.

In the example of FIG. 15, D2? D3 <D1, and
LD interval in LDA0 = | D2-D3 | / (LD number-1)
LD interval in LDA1 = | D1-D3 | / (number of LDs−1)
LDA deviation amount D = (| D2-D3 | + | D1-D3 |)
It becomes. "?" Means that the magnitude relationship is unknown. The same applies hereinafter.

In the example of FIG. 16, D1 <D2? D3,
LD interval in LDA0 = | D1-D3 | / (number of LDs−1)
LD interval in LDA1 = | D1-D2 | / (number of LDs−1)
LDA deviation amount D = D1
It becomes.

In the example of FIG. 17, D2 <D1 <D3,
LD interval in LDA0 = | D1-D3 | / (number of LDs−1)
LD interval in LDA1 = | D1-D2 | / (number of LDs−1)
LDA deviation amount D = D2
It becomes.

  When LDA0 is not tilted, D1 = D3. When LDA1 is not tilted, D1 = D2. When both LDA0 and LDA1 are not tilted, D1 = D2 = D3. From the counter values of D1 to D3, it is possible to detect the positional deviation correction amount in the main scanning direction of the tilted LD in the LDA.

  If the positional deviation correction amount can be detected in this way, the control unit 9 can correct the emission timing with respect to the laser driving circuit 8 based on the correction amount, and thereby correct the deviation amount. As a result, accurate and high-quality image formation can be performed.

  An example of an image forming apparatus provided with such an optical writing device is shown in FIG. FIG. 18 is a diagram showing an outline of a mechanical configuration of a digital copying machine as an image forming apparatus to which the optical writing device according to the present embodiment is applied. In the figure, a digital copying machine is for monochrome image formation, and includes a main body 400, an image reading device 500 installed on the upper portion of the image forming apparatus main body 400, and an automatic document feeder (hereinafter referred to as an automatic document feeder) mounted thereon. , “ADF”) 550, a large-capacity paper feeding device 700 disposed on the right side of the image forming apparatus main body 400 in the same figure, and a sheet post-processing device disposed on the left side of the image forming apparatus main body 400 in the same figure. 800 is basically composed.

  The image forming apparatus main body 400 includes an image writing unit 410, an image forming unit 420, a fixing unit 430, a duplex conveying unit 440, a paper feeding unit 450, a vertical conveying unit 460, and a manual feeding unit 470. The unit 410 corresponds to the optical writing device shown in FIG.

  The image writing unit 410 modulates the LD, which is a light source, based on the image information of the document read by the image reading device 500, and writes laser on the photosensitive drum 421 by a scanning optical system such as a polygon mirror and an fθ lens. is there. The image forming unit 420 includes a photosensitive drum 421 and known electrophotographic imaging elements such as a developing unit 422, a transfer unit 423, a cleaning unit 424, and a charge eliminating unit provided along the outer periphery of the photosensitive drum 421. Consists of.

  The fixing unit 430 fixes the image transferred by the transfer unit 423 on the transfer paper. The double-sided conveyance unit 440 is provided downstream of the fixing unit 420 in the transfer sheet conveyance direction, and includes a first switching claw 441 that switches the transfer sheet conveyance direction to the sheet post-processing device 800 side or the double-side conveyance unit 440 side, , The reverse conveying path 442 guided by the switching claw 441, the image forming side conveying path 443 that conveys the transfer paper reversed by the reverse conveying path 442 to the transfer unit 423 again, and the reverse transfer paper after the sheet post-processing device 800. A second switching claw 445 is disposed at a branch portion between the image forming side conveying path 443 and the post processing side conveying path 444.

  The sheet feeding unit 450 includes four sheet feeding stages, and the transfer sheets stored in the sheet feeding stages selected by the pickup roller and the sheet feeding roller are drawn out and guided to the vertical conveyance unit 460. The vertical conveyance unit 460 conveys the transfer paper fed from each paper feed stage to the registration roller 461 immediately upstream in the paper conveyance direction of the transfer unit 423, and the registration roller 461 provides a visible image on the photosensitive drum 421. The transfer paper is fed into the transfer unit 423 in time with the leading edge. The manual feed portion 470 includes an openable and closable manual feed tray 471, and opens the manual feed tray 471 as needed to supply transfer paper manually. Also in this case, the transfer timing of the transfer paper is taken by the registration roller 461 and is transported.

  The large-capacity paper feeding device 700 supplies a large amount of transfer paper of the same size, and the bottom plate 702 rises as the transfer paper is consumed, so that the paper can always be picked up from the pickup roller 701. ing. The transfer paper fed from the pickup roller 701 is conveyed from the vertical conveyance unit 460 to the nip of the registration roller 461.

  The sheet post-processing apparatus 800 performs predetermined processing such as punching, alignment, stapling, and sorting. In this embodiment, the punch 801, the staple tray (alignment) 802, the stapler 803, and the shift tray 804 are used for the above functions. I have. In other words, the transfer paper carried from the image forming apparatus 400 to the paper post-processing apparatus 800 is punched one by one with the punch 801 when punching, and then if there is no particular processing, the proofing is performed. When sorting, stacking, and sorting to the tray 805, the sheets are discharged to the shift tray 804, respectively. In this embodiment, the sorting is performed by the reciprocating movement of the shift tray 804 by a predetermined amount in a direction orthogonal to the sheet conveyance direction. In addition, sorting can be performed by moving the paper in a direction orthogonal to the paper transport direction on the paper transport path.

  In the case of alignment, the transfer paper that has been punched or not punched is guided to the lower transport path 806, and the staple tray 804 is aligned in the direction perpendicular to the paper transport direction by the rear end fence. In the jogger fence, alignment in the direction parallel to the paper transport direction is performed. Here, when binding is performed, a predetermined position of the aligned sheet bundle, for example, a predetermined position such as a corner portion or two central positions is bound by the stapler 803 and discharged to the shift tray 804 by the discharge belt. In this embodiment, a pre-stack conveyance path 807 is provided in the lower conveyance path 806, and a plurality of sheets are stacked at the time of conveyance to avoid interruption of the image forming operation on the image forming apparatus main body 400 side during post-processing. Be able to.

  The image reading apparatus 500 is guided onto the contact glass 510 by the ADF 600, optically scans the stopped original, and reads the image formed by the imaging lens through the first to third mirrors, such as a CCD or CMOS. Read by the photoelectric conversion element. The read image data is subjected to predetermined image processing by an image processing circuit (not shown) and temporarily stored in a storage device. Then, it is read from the storage device by the image writing unit 410 during image formation, modulated according to the image data, and optical writing is performed.

  The ADF 550 has a double-sided reading function, and is attached to the contact glass 510 installation surface of the image reading device 500 so as to be freely opened and closed. In the ADF 550, the document placed on the document placement table 551 is automatically sent onto the contact glass 510 when the document is read.

  This image reading apparatus can be applied to a digital copying machine, a digital multifunction machine, a FAX, a scanner, and the like.

As described above, according to the present embodiment,
1) Main scanning due to physical factors between a plurality of independent LDs by detecting the light detection interval detected by the photoelectric conversion elements provided at the front and rear ends of the photosensitive member with an internal counter and using the counter value. A direction deviation correction amount can be detected.
2) The light detection interval detected by the photoelectric conversion elements provided at the front and rear ends of the photoreceptor is detected by an internal counter, and the counter value is used to cause a wavelength difference between a plurality of independent LDs. A deviation correction amount in the main scanning direction can be detected.
3) The light detection interval detected by the photoelectric conversion elements provided at the front and rear ends of the photosensitive member is detected by an internal counter, and the physical value between a plurality of LDs built in one LDA is used by using the counter value. A deviation correction amount in the main scanning direction due to the factor can be detected.
4) The light detection interval detected by the photoelectric conversion elements provided at the front and rear ends of the photosensitive member is detected by an internal counter, and the counter value is used to physically connect the plurality of LDs built in the plurality of LDAs. It is possible to detect a deviation correction amount in the main scanning direction due to a factor and a deviation correction amount in the main scanning direction due to a physical factor of the built-in LD that is most adjacent between different LDAs.
5) Main scanning caused by a wavelength difference between a plurality of LDAs by detecting the light detection interval detected by the photoelectric conversion elements provided at the front and rear ends of the photosensitive member by an internal counter and using the counter value. A direction deviation correction amount can be detected.
6) The light detection interval detected by the photoelectric conversion element provided only at the front end of the photosensitive member is detected by an internal counter, and the counter value is used to depend on physical factors between a plurality of LDs incorporated in a plurality of LDAs. It is possible to detect the deviation correction amount in the main scanning direction and the deviation correction amount in the main scanning direction due to the physical factor of the built-in LD that is most adjacent between different LDAs.
There is an effect.

FIG. 2 is a schematic diagram illustrating an optical writing device that forms an electrostatic latent image on a photoreceptor using an LD according to an embodiment of the present invention. It is a timing chart which shows the timing of the main scanning direction shift | offset | difference correction amount detection of LD0-LD1, LD1-LD2, LD2-LD3. It is a timing chart which shows the detection timing of the front-end | tip synchronization detection sensor when the LD0 has shifted | deviated, and a rear-end synchronization detection sensor. It is a timing chart which shows the timing in the case of detecting a front-end | tip and rear-end synchronous timing with the same LD. It is a timing chart which shows an example of the front-end | tip and rear-end detection timing at the time of using 1 LDA which incorporates 4 LD. FIG. 5 is a diagram (part 1) illustrating leading edge and trailing edge synchronization detection timing when a plurality of LDAs are used. FIG. 11 is a diagram (part 2) illustrating the leading edge and trailing edge synchronization detection timing when a plurality of LDAs are used. FIG. 10 is a diagram (part 3) illustrating leading edge and trailing edge synchronization detection timing when a plurality of LDAs are used; FIG. 14 is a diagram (part 4) illustrating the leading edge and trailing edge synchronization detection timing when a plurality of LDAs are used; FIG. 10 is a diagram (No. 5) illustrating the leading edge and trailing edge synchronization detection timing when a plurality of LDAs are used. FIG. 16 is a diagram (No. 6) illustrating the leading edge and trailing edge synchronization detection timing when a plurality of LDAs are used; FIG. 14 is a diagram (No. 7) illustrating the leading edge and trailing edge synchronization detection timing when a plurality of LDAs are used; It is FIG. (8) which shows the front-end | tip and rear-end synchronous detection timing at the time of using multiple LDA. FIG. 6 is a diagram (part 1) illustrating leading edge and trailing edge synchronization detection timings when two LDAs with four LDs are used; FIG. 10 is a diagram (part 2) illustrating the leading edge and trailing edge synchronization detection timing when two LDAs each including four LDs are used; FIG. 11 is a diagram (part 3) illustrating the leading edge and trailing edge synchronization detection timing when two LDAs each including four LDs are used; FIG. 11 is a diagram (part 4) illustrating the leading edge and trailing edge synchronization detection timing when two LDAs each including four LDs are used; 1 is a diagram illustrating an outline of a mechanical configuration of a digital copying machine as an image forming apparatus to which an optical writing device according to an embodiment is applied. It is explanatory drawing which shows inclination (theta) as a physical variation which arises at the time of the assembly | attachment for every body. It is explanatory drawing which shows the inclination of 2 LDA (LDA0 and LDA1) when the beam interval of a subscan is match | combined with 600 dpi.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser diode 2 Polygon mirror 3 Photoconductor 4 Front end synchronous detection sensor 5 Rear end synchronous detection sensor 6 Polygon motor 7 Motor driver 8 Laser drive circuit 9 Control part 400 Image forming apparatus main body 410 Image writing part (optical writing apparatus)
LD0 to LD7 Laser diode LDA1, LDA2 Laser diode array

Claims (13)

A plurality of independent laser diodes that are modulated in response to image signals;
An image carrier irradiated with laser light emitted from the laser diode;
A photoelectric conversion element that is disposed on each of the front end side and the rear end side with respect to the main scanning direction of the image carrier, detects the laser light, and outputs a synchronization signal;
Counting means for counting the light detection interval between the photoelectric conversion elements on the front end side and the rear end side,
Detecting means for detecting a deviation correction amount in the main scanning direction based on the count value counted by the counting means;
An optical writing control device comprising:   2. The optical writing control apparatus according to claim 1, wherein a laser diode array in which the laser diodes are arranged in a plurality of arrays is used instead of the plurality of independent laser diodes.   Detecting the inclination in the main scanning direction of each of the laser diode arrays based on the count value, detecting a main scanning direction deviation correction amount due to a physical factor of the laser diode built in each of the laser diode arrays, 3. The optical writing control device according to claim 2, wherein a deviation correction amount in a main scanning direction of a built-in laser diode that is most adjacent between different laser diode arrays is detected.   4. The optical writing control apparatus according to claim 1, wherein the deviation correction amount is generated due to a physical factor between laser diodes having different amounts.   4. The optical writing control apparatus according to claim 1, wherein the optical writing control apparatus is based on a wavelength difference between laser diodes having different deviation correction amounts. 5. A laser diode array in which a plurality of laser diodes modulated and controlled according to image signals are arranged in an array, and
An image carrier irradiated with laser light emitted from a laser diode of the laser diode array;
A photoelectric conversion element that is disposed on the tip side with respect to the main scanning direction of the image carrier, detects the laser light, and outputs a synchronization signal;
Counting means for counting the light detection interval detected by the photoelectric conversion element on the tip side;
Detecting means for detecting a tilt in the main scanning direction of the laser diode array based on the count value counted by the counting means, and detecting a correction amount of deviation in the main scanning direction of the laser diode built in the laser diode array;
An optical writing control device comprising:   7. The optical writing control apparatus according to claim 1, further comprising a correction unit that corrects a deviation amount in a main scanning direction based on a correction amount detected by the detection unit.   An optical writing device comprising the optical writing control device according to claim 1.   An image forming apparatus comprising the optical writing device according to claim 7. Scanning the image carrier with laser light emitted from a plurality of independent laser diodes whose modulation is controlled according to the image signal in the main scanning direction,
The scanned laser light is disposed on the front end side and the rear end side with respect to the main scanning direction of the image carrier, and is detected by a photoelectric conversion element that detects the laser light and outputs a synchronization signal,
Count the light detection interval between the photoelectric conversion elements on the front end side and the rear end side,
An optical writing control method, comprising: detecting a shift correction amount in a main scanning direction based on the counted value. In place of the plurality of independent laser diodes, a laser diode array in which the laser diodes are arranged in a plurality of arrays,
Detecting the inclination of each of the laser diode arrays based on the count value;
11. The optical writing control method according to claim 10, wherein a main scanning direction shift correction amount of a built-in laser diode that is most adjacent between different laser diode arrays is detected. A laser beam emitted from a laser diode of a laser diode array in which a plurality of laser diodes modulated and controlled according to an image signal are arranged in an array is scanned in the main scanning direction with respect to the image carrier,
The scanned laser beam is arranged on the tip side with respect to the main scanning direction of the image carrier, and is detected by a photoelectric conversion element that detects the laser beam and outputs a synchronization signal,
Count the light detection interval detected by the photoelectric conversion element on the tip side,
Detecting the inclination of the laser diode array in the main scanning direction based on the counted value,
An optical writing control method, wherein a main scanning direction shift correction amount of a laser diode incorporated in the laser diode array is detected.   13. The optical writing control method according to claim 10, wherein a main scanning direction deviation amount is corrected based on the detected correction amount.

Images