JP2010012615A - Image formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image formation device which can not only minimize variation in the life of laser light sources incident to the emission time thereof and enhance the reliability of image quality as an optical scanner, but also can reduce the failure rate of the laser light source and extend the maintenance deadline. <P>SOLUTION: An image formation device includes a driver 43 which carries out modulation driving of the output from a plurality of laser light sources for irradiation with laser beams, an imaging optical system 32 which carries out imaging of a beam subjected to deflection scanning by a rotating polygonal mirror 31 as a minute spot on a photoconductor drum 19, an HDD 45 which stores the accumulation luminescence times of the plurality of laser light sources in the second speed mode in correspondence with the plurality of laser light sources, and a light source selection control section which selects the plurality of laser light sources for use in the second speed mode so that the accumulation luminescence times of the plurality of laser light sources in the second speed mode are equalized by comparing the accumulation luminescence times stored in the HDD 45. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine functionally equipped with these, in particular, a plurality of laser light sources for irradiating a beam based on image information, A driver that modulates and drives the output of each laser light source, a rotary polygon mirror that deflects and scans a plurality of beams emitted from the plurality of laser light sources in the main scanning direction by the same plane, and deflection scanning by the rotary polygon mirror The present invention relates to an image forming apparatus equipped with an optical scanning device provided with an imaging optical system that forms an image of the obtained beam as a minute spot on an electrostatic latent image carrier.

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine equipped with these functions has been equipped with an optical scanning device, and a light beam emitted from a light source of the optical scanning device is used. By irradiating the surface of the photoconductor (scanned surface), the electrostatic latent image formed on the surface of the photoconductor is revealed by toner, and the toner image is transferred and fixed on transfer paper, thereby realizing image forming processing. ing.

  At this time, the optical scanning device includes a plurality of laser light sources that irradiate a beam based on image information, a driver that modulates and drives outputs of the plurality of laser light sources, and a plurality of laser light sources that are irradiated from the plurality of laser light sources. A rotating polygon mirror that deflects and scans the beam in the main scanning direction on the same surface; and an imaging optical system that forms an image of the beam deflected and scanned by the rotating polygon mirror as a minute spot on the electrostatic latent image carrier. Are well known.

  That is, by using a plurality of laser light sources, the beam emitted from each laser light source is deflected and scanned by a common rotary polygon mirror, and swept as a smile spot in units of microns on a common electrostatic latent image carrier, The speed of image forming processing is realized, and the number of beams is known to use an even number such as 2 beams, 4 beams, 8 beams, and the like.

  On the other hand, in image forming processing using these multiple beams, for example, image quality such as image fixability when plain paper is used as transfer paper does not cause a problem even if it is performed at high speed, but a cardboard or OHP sheet When image quality is used as transfer paper, image quality such as image fixability is easily impaired when performed at high speed.

  Therefore, in order to maintain the image quality due to the type of transfer paper and the like, a plurality of laser light sources are all used on the electrostatic latent image carrier that moves in the sub-scanning direction at the first speed. The electrostatic latent image that moves in the sub-scanning direction at a second speed that is approximately half the speed of the first speed while the recording speed during the image forming process is the same as that in the first speed mode. It is assumed that there is at least two speed modes of a second speed mode that selectively uses a part of a plurality (even number) of laser light sources on the carrier, and image quality is impaired. In the case of the type of transfer paper to be processed, it is conceivable to perform processing in the second speed mode in which the speed of the image forming process is halved.

  In this case, the rotary polygon mirror of the optical scanning device adopts a measure that reduces the number of rotations by half and further reduces the laser output emitted from the laser light source by half.

  However, if the rotational speed of the rotary polygon mirror is halved, the rotational stability of the drive device such as a motor is very difficult due to the balance with the mode that rotates at full speed, and the use of a high-performance drive device reduces the component cost. There was a problem of soaring.

  In addition, in order to reduce the output of the laser light source by half (or multiple stages), the drive circuit (driver) of the laser light source is required to have high performance, resulting in a problem that the cost of parts increases.

  Therefore, for such a problem, for example, in an image forming apparatus that simultaneously writes four lines with four beams during the high-speed image forming process that is the first speed mode, the number of light-emitting beams is set in the second speed mode. By using two beams, a technique is known in which the rotational speed of the rotary polygon mirror driving device is equivalent to that at full speed (see, for example, Patent Document 1).

  However, for example, if four beams are used in the high-speed image forming process and only two beams are simply used in the second speed mode, the other two laser light sources are not used.

  In general, a semiconductor laser or LED used in such a laser light source has a total light emission time that is relatively related to the component life. There is a difference in lifetime between individual laser light sources, and the maintenance time is advanced and the probability of occurrence of abnormal images increases.

The total number of images formed in the second speed mode and the number printed by each laser light source are stored, and a technique for selecting a laser light source that emits light so that the number printed by each laser light source is the same (for example, , Patent Document 2), and a technique for preventing a non-light-emitting state by using a multi-emitting laser light source separately for electrostatic latent image creation and a static elimination light source in accordance with a speed change (for example, refer to Patent Document 3). ) Is also known.
JP 2001-171164 A JP 2003-136780 A JP 2007-121536 A

  However, in the image forming apparatus configured as described above, for example, in the technique disclosed in Patent Document 2, although the number of prints for each laser light source is average, the actual light emission time for each laser light source is Since the corresponding print data (image data) differs from data to data, the actual number of prints is not the cumulative light emission time of the laser light source, and the problem of variations in the life of the laser light source has not been solved. It was.

  In the technique disclosed in Patent Document 3, the light emission time of the multi-emitting laser light source is made uniform by avoiding the non-light emission state and devising the light emission pattern. For example, image formation with a low printing rate is performed. When a large amount of processing continues, there is a concern that the neutralization function cannot be satisfied if the erase light amount and erase time when used as the neutralization light are combined.

  Therefore, in consideration of the above circumstances, the present invention can contribute to equalization of driving opportunities for a plurality of laser light sources, and can suppress variations in lifetimes associated with light emission times of the respective laser light sources. It is an object of the present invention to provide an image forming apparatus that can not only improve the reliability of the image quality, but also reduce the failure rate of the laser light source and extend the maintenance period.

  An image forming apparatus according to the present invention includes a plurality of laser light sources for irradiating a beam based on image information, a driver for modulating and driving outputs of the plurality of laser light sources, and a plurality of laser light sources irradiated from the plurality of laser light sources. A rotary polygon mirror that deflects and scans the beam in the main scanning direction on the same plane, and an imaging optical system that forms an image of the beam deflected and scanned by the rotary polygon mirror as a minute spot on the electrostatic latent image carrier. A first speed mode in which all of the plurality of laser light sources are used on the electrostatic latent image carrier that moves in the sub-scanning direction at a first speed, and a recording density at the time of image forming processing is the first density One of the plurality of laser light sources on the electrostatic latent image carrier that moves in the sub-scanning direction at a second speed that is approximately half the first speed while maintaining the same speed mode as Second speed mode to selectively use A storage unit that stores the accumulated light emission times of the plurality of laser light sources in the second speed mode corresponding to the plurality of laser light sources, and the storage unit. A light source for selecting the plurality of laser light sources to be used in the second speed mode so that the accumulated light emission times of the plurality of laser light sources in the second speed mode are equalized by comparing the accumulated light emission times stored in the second speed mode And a selection control unit.

Also, the image forming apparatus of the present invention is irradiated with an even number of laser light sources that irradiate a beam based on image information, a driver that modulates and drives the output of the even number of laser light sources, and the even number of laser light sources. A rotating polygon mirror that deflects and scans a plurality of beams in the main scanning direction by the same surface, and an imaging optical system that forms an image of the beam deflected and scanned by the rotating polygon mirror as a minute spot on the electrostatic latent image carrier; With
A first speed mode in which all the even number of laser light sources are used on the electrostatic latent image carrier that moves in the sub-scanning direction at a first speed, and a recording density at the time of image forming processing is the first speed. A half of the even number of laser light sources is placed on the electrostatic latent image carrier that moves in the sub-scanning direction at a second speed that is approximately half the first speed while maintaining the same mode. For at least two speed modes of the second speed mode to be selectively used, the cumulative printing rate of each of the even number of laser light sources in the second speed mode corresponds to the plurality of laser light sources. In the second speed mode so that the cumulative print ratios of the plurality of laser light sources in the second speed mode are equal by comparing the storage section stored in the storage section and the cumulative print ratios stored in the storage section. Select the plurality of laser light sources to be used. A light source selection control section that, and in that comprises a.

  At this time, the light source selection control unit compares the accumulated light emission time or accumulated printing rate stored in the storage unit when a series of image forming processes is completed, and then performs image formation in the next second speed mode. It is preferable to select the plurality of laser light sources to be used when processing is started.

  The light source selection control unit compares the accumulated light emission time or the accumulated printing rate stored in the storage unit when the image forming apparatus main body starts the aging mode, and then compares the image in the next second speed mode. It is also possible to select the plurality of laser light sources to be used when the forming process is started.

  The present invention can contribute to equalization of driving opportunities for a plurality of laser light sources, can suppress variations in the lifetime associated with the light emission time of each laser light source, and can improve the reliability of image quality as an optical scanning device. Not only can it be improved, it is possible to reduce the failure rate of the laser light source and extend the maintenance period.

  Next, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is an explanatory diagram of an image forming apparatus equipped with an optical scanning device according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the optical scanning device according to an embodiment of the present invention.

(Overall configuration of image forming apparatus)
As shown in FIG. 1, a printer 1 as an image forming apparatus according to an embodiment of the present invention includes a paper feed cassette 3 that is slidably stored in a printer main body 2 as an image forming apparatus main body, and a paper supply cassette 3. A paper feed unit 5 for taking out transfer paper (not shown) stored in the storage space 4 of the paper cassette 3, a manual feed tray 6 arranged in front of the printer main body 2, and transfer paper (set in the manual feed tray 6) (Not shown), a manual feed unit 7 for taking out, a conveyance path 8 for conveying transfer paper supplied from the respective sheet feeding units 5, 7, and each sheet feeding unit 5 upstream of the conveyance path 8 in the sheet conveyance direction. , 7 and the registration roller pair 9 disposed on the downstream side in the sheet conveyance direction, and the toner supplied from the toner container 10 on the conveyance path 8 downstream of the registration roller pair 9 in the sheet conveyance direction. One side of transfer paper with developer An image forming unit 11 that forms a transfer image, a fixing device 12 that is disposed downstream of the image forming unit 11 in the sheet conveyance direction of the conveyance path 8 and fixes a toner image formed on one surface of the transfer paper, and a fixing device When a transfer image is formed on the other surface of the transfer paper that has passed through 12, the reversing path is pulled back from the downstream side of the conveying path from the fixing device 12 of the conveying path 8 to the upstream side of the conveying path of the conveying path 8 from the pair of registration rollers 9. 13 and a paper discharge unit 14 provided at the end of the conveyance path 8.

(Configuration of toner container 10)
The toner container 10 stores replenishment toner inside the container body 15. Further, the replenishing toner is agitated by a paddle 16 made of a flexible resin material or the like, and is conveyed in the transfer paper width direction (the depth direction in FIG. 1) by the spiral 17, and then forms an image at the predetermined position. Supplied to the developing device 18 of the section 11.

(Configuration of developing device 18)
The developing device 18 supplies the toner for replenishment supplied from the toner container 10 to the photosensitive drum 19 of the image forming unit 11 while stirring the toner, and a pair of spirals 21 in a state where the developing device 18 is partitioned by a partition wall 20. , 22 are arranged.

  Both ends of the partition wall 20 (in the depth direction in FIG. 1) are opened so as to communicate between both ends of the spirals 21 and 22, and are directed toward one side of the developing device 18 by the spiral 21 provided below the spiral 17. After the toner is agitated and conveyed (forward path), the toner is turned back at the open end of one side of the partition wall, and the replenishing toner is agitated and conveyed (return path) toward the other side of the developing device 18 by the spiral 22. A circulation conveyance path is formed that is turned back again at the open end of the partition wall. The spiral 22 is provided with a developing roller 23 that contacts the photosensitive drum 19 and supplies replenishing toner.

  The developing roller 23 is disposed so that the peripheral surface thereof faces the peripheral surface of the photosensitive drum 19. Therefore, the replenishment toner being conveyed to the developing roller 23 is supplied to the peripheral surface of the photosensitive drum 19 via the developing roller 23, thereby forming a toner image on the peripheral surface of the photosensitive drum 19. Become. At this time, the developing roller (magnet roller) 23 supplies the toner to the photosensitive drum 19 while appropriately stirring so as not to aggregate the toner.

(Configuration of the image forming unit 11)
The image forming unit 11 includes a charging device 24, an exposure device 25, and a developing device 18 (developing roller 23) around the photosensitive drum 19 in the order of the image forming process along the rotation direction (clockwise direction in the drawing) of the photosensitive drum 19. A transfer device 26, a cleaning device 27, and a static elimination device 28 are provided.

  As a result, in the image forming unit 11, the photosensitive drum 19 is rotationally driven at a predetermined process speed (circumferential speed) by a driving unit (not shown), and the surface thereof is uniformly charged to a predetermined polarity and potential by the charging device 24. .

  An electrostatic latent image is formed on the surface of the charged photosensitive drum 19 by the exposure device 25. Here, the exposure device 25 irradiates the surface of the photosensitive drum 19 with the laser beam P based on the image data included in the print data output from the personal computer or the like, and irradiates the laser beam on the surface of the photosensitive drum 19. An electrostatic latent image corresponding to the image information is formed by removing the charge of the portion.

  The electrostatic latent image formed on the surface of the photosensitive drum 19 is developed as an unfixed toner image by electrostatically attaching toner having a charge supplied from the toner container 10 by the developing device 18. Further, the unfixed toner image is transferred onto the transfer paper as a transfer image by the transfer device 26.

  At this time, the photosensitive drum 19 on which the unfixed toner image is transferred to the transfer paper is subjected to a removal process of residual toner and the like by the cleaning device 27, and then is discharged by the charge removal device 28 for charging at the next image formation. Processing is performed.

(Configuration of exposure device 25)
As shown in FIG. 2, the exposure device 25 as an optical scanning device includes a light source unit 29 holding a plurality of laser light sources (not shown) such as laser diodes that emit beam beams, and each laser light source of the light source unit 29. The cylindrical lens 30 having a positive power only in the sub-scanning direction and the deflecting device for deflecting the beam light beam from the cylindrical lens 30 so that the beam light beam irradiated from the cylindrical lens 30 is condensed in a substantially linear shape long in the main scanning direction. A rotating polygon mirror 31, an imaging optical system 32 that forms an image on the surface of the photosensitive drum 19 as a scanning surface, and a beam beam deflected and scanned by the rotating polygon mirror 31. And a detection optical system 34 that leads to the light receiving element 33 that detects scanning synchronization by using a part of the detection optical system 34.

  The imaging optical system 32 is disposed in the vicinity of the rotating polygon mirror 31 and has a negative resin lens 35 with a strong power in the sub-scanning direction, and is spaced apart from the rotating polygon mirror 31 and has a positive power in the sub-scanning direction. 36 and an oblique mirror 37 that reflects the beam P transmitted through the resin lens 36 toward the photosensitive drum 19. In the present embodiment, the resin lens 35 and the resin lens 36 constitute a pair of fθ lenses.

  The detection optical system 34 includes a light guide mirror 38 disposed outside the effective image area so as to reflect a part of the beam beam incident on the mirror surface of the rotary polygon mirror 31, and a photosensitive drum on the optical path of the detection optical system 34. 19 and a light receiving element 33 provided at a position conjugate with the light receiving element 19.

  The beam light beam emitted from the light source unit 29 and deflected by the rotary polygon mirror 31 is deflected toward the scanning region by the imaging optical system 32. On the way to the scanning region, one resin lens 35 constituting the fθ lens. Is reflected by the light guide mirror 38 and enters the light receiving element 33.

  On the other hand, the printer 1 has a first speed mode in which all of a plurality of laser light sources are used on the photosensitive drum 19 moving in the sub-scanning direction at a first speed, and the recording density during the image forming process is the first. One of a plurality of laser light sources is selectively used on the photosensitive drum 19 that moves in the sub-scanning direction at a second speed that is approximately half the first speed while maintaining the same speed mode. Output from a personal computer or a mode designation operation (including a transfer paper type designation (automatic detection) operation) using an operation panel (not shown). Each mode is switched according to the mode designation included in the print data.

  Control information relating to each mode is stored in the ROM 40 together with control information relating to the overall image forming process, and is controlled by a control circuit (CPU) 41.

  Further, the control circuit 41, for example, causes the image analysis unit 42 to analyze the image data included in the print data output from the personal computer, and includes a light source including which laser light source to use in association with the speed mode described above. The driver 43 of the unit 29 is controlled.

  Specifically, when the first speed mode is designated by the print data output from the personal computer, the print data including the speed mode (for example, the number of image forming processing units, the enlargement / reduction ratio, etc.) The control circuit 41 calls the control information stored in the ROM 40 and stores the image formation processing control information corresponding to the print data such as the mode in the RAM 44 and also based on the image data analyzed by the image analysis unit 42. The driver 43 is controlled so that all the laser light sources of the light source unit 29 are controlled to emit light. Note that the image data at this time is stored in the HDD 45.

  On the other hand, when the second speed mode is designated by the print data output from the personal computer, the ROM 40 is obtained from the print data including the speed mode (for example, the number of image forming processing units and the enlargement / reduction ratio). The control circuit 41 calls the control information stored in the image data, stores the image forming process control information corresponding to the print data such as the mode in the RAM 44, and the light source unit 29 based on the image data analyzed by the image analysis unit 42. The driver 43 is controlled so that light emission is controlled at the same time as the laser light source to be used is selected from the laser light sources.

  At this time, the control circuit 41 stores the drive time of the driver 43, that is, the accumulated light emission time of each laser light source in the HDD 45 in association with the designated laser light source.

  The control circuit 41 calculates the printing rate based on the number of pages and the number of copies included in the print data and the image data analyzed by the image analysis unit 42, and stores the cumulative printing rate associated with the selected laser light source in the HDD 45. It may be stored.

  The control circuit 41 compares, for example, the cumulative light emission time or cumulative print rate for each laser light source stored in the HDD 45 when a series of image forming processes is completed, and then the cumulative light emission time or cumulative value stored in the HDD 45. A laser light source to be used when the image forming process in the next second speed mode is started is selected so that the printing rate becomes equal for each of the plurality of laser light sources.

  Further, the control circuit 41 compares the accumulated light emission time or accumulated print rate for each laser light source stored in the HDD 45 when the printer 1 starts the aging mode, and then compares the accumulated light emission time or accumulated print rate stored in the HDD 45. The laser light source to be used when the image forming process in the next second speed mode is started is selected so that is equal for each of the plurality of laser light sources.

  Note that the activation timing of the aging mode of the printer 1 described above is often set so that color calibration is automatically entered even during a job in the case of a color machine different from the monochrome machine shown in FIG. The laser light source selection control can be performed at that timing.

  The number of laser light sources mounted on the light source unit 29 is not limited as long as it is two or more (even numbers).

  At this time, for example, when there are four laser light sources (four beams), any two laser light sources in the half-speed mode (second speed mode) are used, and a combination of the two laser light sources. That is, the accumulated light emission time or accumulated print rate as a half-speed unit light source may be stored in the HDD 45 and may be selected and controlled for each combination unit (half-speed unit light source unit), or the minimum accumulated light emission time for each laser light source Alternatively, two of the minimum cumulative printing rates may be selected and combined.

  For example, even in the case of 8 beams, the four laser light sources to be used can be combined or independently controlled.

It is explanatory drawing of the image forming apparatus carrying the optical scanning device which concerns on one Embodiment of this invention. It is an optical explanatory view of the optical scanning device concerning one embodiment of the present invention.

Explanation of symbols

19 ... Photosensitive drum (electrostatic latent image carrier)
29 ... Light source unit (plural laser light sources)
31 ... Rotating polygon mirror 41 ... Control circuit (light source selection control unit)
43 ... Driver 45 ... HDD (storage unit)

Claims (4)

A plurality of laser light sources for irradiating a beam based on image information, a driver for modulating and driving the outputs of the plurality of laser light sources, and a plurality of beams emitted from the plurality of laser light sources are scanned in the same plane. A rotating polygon mirror that deflects and scans in the direction; and an imaging optical system that forms an image of the beam deflected and scanned by the rotating polygon mirror as a minute spot on the electrostatic latent image carrier,
A first speed mode in which all of the plurality of laser light sources are used on the electrostatic latent image carrier that moves in the sub-scanning direction at a first speed, and the recording density during the image forming process is the first speed. One of the plurality of laser light sources is placed on the electrostatic latent image carrier that moves in the sub-scanning direction at a second speed that is approximately half the first speed while maintaining the same mode. For at least two speed modes, the second speed mode to be used selectively,
A storage unit that stores the accumulated light emission time of each of the plurality of laser light sources in the second speed mode corresponding to the plurality of laser light sources is compared with the accumulated light emission time stored in the storage unit. A light source selection control unit that selects the plurality of laser light sources to be used in the second speed mode so that the accumulated light emission times of the plurality of laser light sources in the second speed mode are equal to each other. An image forming apparatus. An even number of laser light sources for irradiating a beam based on image information, a driver for modulating and driving the output of the even number of laser light sources, and a plurality of beams emitted from the even number of laser light sources are scanned in the same plane. A rotating polygon mirror that deflects and scans in the direction; and an imaging optical system that forms an image of the beam deflected and scanned by the rotating polygon mirror as a minute spot on the electrostatic latent image carrier,
A first speed mode in which all the even number of laser light sources are used on the electrostatic latent image carrier that moves in the sub-scanning direction at a first speed, and a recording density at the time of image forming processing is the first speed. A half of the even number of laser light sources is placed on the electrostatic latent image carrier that moves in the sub-scanning direction at a second speed that is approximately half the first speed while maintaining the same mode. For at least two speed modes, the second speed mode to be used selectively,
A storage unit that stores the cumulative printing rate of each of the even number of laser light sources in the second speed mode corresponding to the plurality of laser light sources is compared with the cumulative printing rate stored in the storage unit. A light source selection control unit that selects the plurality of laser light sources to be used in the second speed mode so that the cumulative printing rates of the plurality of laser light sources in the second speed mode are equal to each other. An image forming apparatus.   The light source selection control unit compares the accumulated light emission time or accumulated printing rate stored in the storage unit when a series of image forming processes is completed, and then starts the next image forming process in the second speed mode. The image forming apparatus according to claim 1, wherein the plurality of laser light sources to be used at the time of selection are selected.   The light source selection control unit compares the accumulated light emission time or accumulated printing rate stored in the storage unit when the image forming apparatus main body starts the aging mode, and then performs image formation processing in the next second speed mode. 4. The image forming apparatus according to claim 1, wherein the plurality of laser light sources to be used when the start is started are selected. 5.

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