JP5407942B2 - Image forming apparatus, optical scanning apparatus, and integrated circuit - Google Patents

Description

  The present invention relates to an image forming apparatus, an optical scanning device, and an integrated circuit.

  2. Description of the Related Art Conventionally, image forming apparatuses such as laser printers, digital copying machines, facsimile machines, and the like scan and deflect laser light on a surface to be scanned such as a photosensitive member by a scanning unit in the main scanning direction, and also scan the surface to be scanned in the sub-scanning direction. And an apparatus for writing an image for each line on the image carrier. Such an image forming apparatus is called a beam scanning image forming apparatus.

  As a laser beam deflection method of the beam scanning type image forming apparatus, equiangular velocity deflection using a polygon mirror, reciprocating scanning deflection using a resonance mirror, or the like is used.

  In the equiangular velocity deflection, the scanning direction is a constant direction of the surface to be scanned.

  On the other hand, in reciprocating scanning deflection, a light beam from a light source is deflected by reciprocating deflecting means such as a resonance mirror and guided to a surface to be scanned. When the surface to be scanned is reciprocally scanned, the scanning direction is reversed every time one line is scanned, and in the next scanning, the line is scanned in the reverse direction.

  The reciprocating scanning deflection further reciprocates the surface to be scanned and moves the image carrier in the sub-scanning direction, so that the light beam spot position on the surface to be scanned is changed from the beginning to the end of one line in the main scanning direction. It shifts in the sub-scanning direction by the scanning time. As a result, in the two-dimensional image formed on the surface to be scanned, the density of the interval between both ends of the main scanning occurs. This density is a factor in reducing the image quality of the formed image. Visually, density unevenness may be felt near the center and the end in the main scanning direction.

  In order to suppress these degradations in image quality, for example, Japanese Patent Application Laid-Open No. 2009-003203 (Patent Document 1) has a liquid optical element in which a condensing position according to an applied voltage is variable in a scanning optical system, An invention of a light beam scanning optical device is disclosed in which the condensing position of the liquid optical element is changed in the forward path and the backward path, and the condensing position in the sub-scanning direction is corrected within one line in the scanning direction.

  However, the correction of the condensing position by the liquid optical element disclosed in Patent Document 1 increases the cost of the optical element and the optical scanning device related to the condensing position varying means.

  The present invention has been invented in order to solve these problems in view of the above points. In a reciprocating scanning optical system, the increase in the number of optical element parts is reduced, and a simple configuration is used. It is an object of the present invention to provide an image forming apparatus, an optical scanning apparatus, and an integrated circuit that suppress uneven density in a dimensional image.

  In order to achieve the above object, the image forming apparatus of the present invention employs the following configuration.

The image forming apparatus of the present invention includes a light source unit that generates a plurality of light beams, a deflection unit that performs polarization scanning of the plurality of light beams by a deflection surface that performs reciprocating rotation, and a surface to be scanned for the plurality of light beams that have been deflected and scanned. An imaging optical system that forms an image of a two-dimensional image by moving in the upper sub-scanning direction, and a connection at a point in the two-dimensional image where the forward and backward directions of the plurality of light beams deflected and scanned overlap. an image, the control performed in either the forward direction or the backward direction, have a, a write control means for eliminating the overlap of the image by the plurality of light beams, the write control means, said plurality of light beams When performing control so that the forward imaging by the plurality of light beams and the backward imaging by the plurality of light beams become substantially rectangular, the light emission timing of the light source means and the imaging points included in the substantially rectangular are Based on the position and said The order of pixel dimension image, and the inclination correction with respect to one direction of the forward direction or the backward direction, include a mirroring process to reverse the order of the pixel can be configured to perform the reordering .

  Thereby, in the reciprocating scanning optical system, it is possible to provide an image forming apparatus that reduces an increase in the number of optical element parts and suppresses density unevenness of a two-dimensional image to be formed with a simple configuration.

The optical scanning device of the present invention includes a deflecting unit that performs polarization scanning of a plurality of light beams by a deflecting surface that performs reciprocating rotational movement, and moves the plurality of light beams that have been deflected and scanned in a sub-scanning direction on the surface to be scanned. An imaging optical system for forming an image, and imaging at a point where the forward direction and the backward direction of the plurality of light beams deflected and scanned in the two-dimensional image overlap, either the forward direction or the backward direction by contrast control performed in, have a, a write control means for eliminating the overlap of the image by the plurality of light beams, the write control means, the forward direction of the imaging by the plurality of light beams, and the plurality When performing the control to make each of the imagings in the backward direction by the luminous fluxes into a substantially rectangular shape, based on the light emission timing of the light source means and the position of the imaging point included in the substantially rectangular shape, Tilt correction processing for pixel order , To one direction of the forward direction or the backward direction, it includes a mirroring process to reverse the order of the pixel can be configured to perform the reordering.

  As a result, in the reciprocating scanning optical system, it is possible to provide an optical scanning device that reduces an increase in the number of optical element components and suppresses density unevenness of a two-dimensional image to be formed with a simple configuration.

The integrated circuit according to the present invention has a plurality of light beams incident on an imaging optical system that forms a two-dimensional image, deflected in a substantially main scanning direction by a deflecting surface that performs reciprocating rotational movement, with respect to the deflecting means. An integrated circuit for generating a control signal for light source means for emitting a light beam, wherein an input circuit to which a synchronization signal in the main scanning direction in the imaging optical system is input, and the two-dimensional image is deflected and scanned A control circuit that eliminates the overlapping of the imaging due to the plurality of light beams by controlling to perform imaging at a point where the forward direction and the backward direction of the plurality of light beams overlap with either the forward direction or the return direction; Yes, and the control circuit, imaging of the forward direction by the plurality of light beams, and each backward direction of the imaging by the plurality of light beams, when performing control to be substantially rectangular, light emission of the light source means Timing and before Based on the position of the image forming point included in the substantially rectangular shape, the pixel arrangement order of the two-dimensional image is reversed with respect to the inclination correction processing and one of the forward direction and the backward direction. It is possible to adopt a configuration in which rearrangement is performed including mirroring processing .

  Thereby, in the reciprocating scanning optical system, it is possible to provide an integrated circuit that reduces an increase in the number of optical element parts and suppresses density unevenness of a two-dimensional image to be formed with a simple configuration.

  According to the image forming apparatus, the optical scanning apparatus, and the integrated circuit of the present invention, in the reciprocating scanning optical system, the increase in the number of optical element parts is reduced and the density unevenness of the formed two-dimensional image is suppressed with a simple configuration. It is possible to provide an image forming apparatus, an optical scanning apparatus, and an integrated circuit.

FIG. 1 is a diagram for explaining the component arrangement of the image forming apparatus according to the present embodiment. FIG. 2 is a diagram for explaining the details of the optical system 20. FIG. 3 is a diagram for explaining a position where an image is formed on the image carrier by the deflection of the reciprocating deflector 24. FIG. 4 is a diagram schematically illustrating the imaging position. FIG. 5 is a diagram for explaining the density produced in the image formed on the medium by the reciprocating scanning. FIG. 6 is a diagram showing a scanning trajectory of reciprocating scanning with a plurality of light sources. FIG. 7 is a diagram in which the scanning trajectory in the forward direction is emphasized among the scanning trajectories. FIG. 8 is a diagram in which the scanning trajectory in the backward direction is emphasized among the scanning trajectories. FIG. 9 is a diagram in which both the scanning trajectory in the forward direction and the scanning trajectory in the backward direction are overlapped. FIG. 10 is a diagram illustrating an example in which the overlapping of the scanning trajectory in the forward direction and the backward direction is eliminated. FIG. 11 is a diagram for explaining conversion of input data into a substantially rectangular shape. FIG. 12 is a diagram for explaining the imaging position of an image formed by the image forming apparatus according to the present embodiment.

Hereinafter, the present embodiment will be described with reference to the drawings.
[Embodiment]
FIG. 1 is a diagram for explaining the component arrangement of the image forming apparatus according to the present embodiment. The image forming apparatus in FIG. 1 includes a process unit 10, an optical system 20, and a paper feed tray 30. The optical system 20 guides the laser light emitted from the laser diode unit to the process unit 10.

  The process unit 10 includes four writing units 1 a to 1 d and a conveying belt 3. All writing units have the same configuration. In the following description, any one of the writing units is referred to as “writing unit 1”.

  The writing unit 1 includes a photosensitive drum 8, a charging unit 9, a developing unit 6, and a transfer unit 11. The photosensitive drum 8 is charged, forms a latent image with laser light, forms a developed image with toner attached thereto, and transfers the image to a medium.

  The charging unit 9 attaches charges to the photosensitive drum 8. The developing unit 6 attaches one color toner to the photosensitive drum 8 on which the latent image is formed. The transfer unit 11 transfers the image formed on the photosensitive drum 8 onto the medium.

  The paper feed tray 30 stores a medium. The media stored in the paper feed tray are sent one by one onto the conveyor belt 3 to form an image.

  FIG. 2 is a diagram for explaining the details of the optical system 20. The optical system 20 in FIG. 2 includes a writing control unit 21, a light source driving unit 22, a laser diode unit (hereinafter referred to as “LD unit”) 23, a reciprocating deflector 24, and an imaging optical unit 25.

  The writing control unit 21 determines the light emission timing of the laser diode included in the LD unit 23 from the input image data and the synchronization signal in the sub-scanning direction of the laser light guided by the imaging optical unit 25.

  The light source driving means 22 controls the turning on and off of the laser diode of the LD unit 23 at the timing determined by the writing control unit 21. The LD unit 23 causes the laser diode to emit light under the control of the light source driving means 22. The laser light emitted from the laser diode is converted into a parallel light beam and is focused in the sub-scanning direction near the reciprocating deflector 24 by a cylindrical lens or the like. The LD unit 23 has a plurality of light sources, and the laser light emitted from the LD unit 23 has a plurality of light beams.

  The reciprocating deflector 24 deflects the shaped light beam emitted from the LD unit 23 and makes it incident on the imaging optical unit 25. The reciprocating deflector 24 includes reciprocating deflecting means such as a resonance mirror.

  The imaging optical unit 25 scans the light beam deflected by the reciprocating deflector 24 on the photosensitive drum 8 at a substantially constant speed by a scanning lens or the like.

  FIG. 3 is a diagram for explaining the position (spot position of the light beam) formed on the image carrier (photosensitive drum 8) by the deflection of the reciprocating deflector 24. FIG. Although the reciprocating deflector 24 deflects a plurality of light beams, FIG. 3 shows one light beam.

  In FIG. 3, the scanning direction is reversed every time one line is scanned, and in the next scanning in the main scanning direction, scanning is performed in the direction opposite to the previous line. The light beam reciprocally scans the surface to be scanned and moves the image carrier (photosensitive drum 8) in the sub-scanning direction.

  FIG. 4 is a diagram schematically showing the imaging position shown in FIG. In FIG. 4, the spot position of the light beam on the surface to be scanned on the image carrier is shifted in the sub-scanning direction between the start and end of one line in the main scanning direction. This deviation is proportional to the scanning speed in the sub-scanning direction.

  As a result, in the two-dimensional image formed on the surface to be scanned, there are coarse and dense intervals at both ends in the main scanning direction. FIG. 5 is a diagram illustrating an example in which density unevenness occurs between the central portion and the end portion in the main scanning direction. The example of FIG. 5 is obtained by transferring an image developed by attaching toner to a latent image formed by laser light and transferring it to a medium. In the latent image, the light beam spot overlaps the end in the main scanning direction. When this is developed, the amount of toner adhering does not exceed the maximum amount even at the overlapped portion, and the end portion becomes thin. Therefore, in order to suppress density unevenness, it is effective to eliminate the density of the end portions.

  FIG. 6 is a diagram showing a scanning trajectory of reciprocating scanning with a plurality of light sources. FIG. 7 is a diagram in which the scanning trajectory in the forward direction is emphasized among the scanning trajectories in FIG. FIG. 8 is a diagram in which the scanning trajectory in the backward direction is emphasized among the scanning trajectories in FIG.

  FIG. 9 is a diagram in which both the scanning trajectory in the forward direction and the scanning trajectory in the backward direction are overlapped. From FIG. 9, the density at the overlapping point is higher than the other points, and proper image formation cannot be performed. Therefore, it is necessary to rearrange output data suitable for image formation.

  FIG. 10 is a diagram illustrating an example in which the overlapping of the scanning trajectory in the forward direction and the backward direction is eliminated. In FIG. 10, each line in the forward direction and the backward direction has a shape close to a rectangle.

  FIG. 11 is a diagram for explaining conversion of input data into a substantially rectangular shape shown in FIG. FIG. 11A is a diagram for explaining input image data. In the input image data, the main scanning direction is perpendicular to the sub-scanning direction. FIG. 11B is a diagram illustrating an example in which the image data of FIG. 11A is scanned by reciprocal scanning. From FIG. 11b, when the input image data is reciprocally scanned in the arrangement order, the formed image is distorted.

  Therefore, the order of the pixels is rearranged with respect to the input image data. More specifically, tilt correction is performed, and rearrangement for switching output data across a plurality of light sources is performed.

  Further, for reciprocal scanning, a mirroring process is performed to reverse the pixel arrangement order in either the forward direction or the backward direction.

  As shown in FIG. 3, the locus of one light beam draws a sine curve. Therefore, rearrangement for correcting the sine curve is performed. For example, by performing simple inclination correction, the sine curve can be corrected with a simple configuration.

  FIG. 12 is a diagram for explaining the imaging position of an image formed by the image forming apparatus according to the present embodiment. In FIG. 12, the imaging points formed by a plurality of light beams have a substantially rectangular shape in each of the forward direction and the backward direction.

(Realization by computer etc.)
The image forming apparatus according to the embodiment of the present invention may be realized by a personal computer (PC), for example. In addition, the image forming method according to the embodiment of the present invention is executed by using, for example, a main memory such as a RAM as a work area in accordance with a program stored in a ROM or a hard disk device by a CPU.

  Although the best mode for carrying out the invention has been described above, the present invention is not limited to the embodiment described in the best mode. Modifications can be made without departing from the spirit of the present invention.

  As described above, the image forming apparatus according to the present invention is useful for forming a high-speed image, and is particularly suitable for a printer.

1, 1a Writing unit 3 Conveying belt 6 Developing unit 8 Photosensitive drum 9 Charging unit 10 Process unit 11 Transfer unit 20 Optical system 21 Writing control unit 22 Light source driving means 23 LD unit 24 Reciprocating deflector 25 Imaging optical unit 30 Paper feed tray

JP 2009-003203 A

Claims (3)

Light source means for generating a plurality of light fluxes;
Deflection means for polarizing and scanning the plurality of light beams by a deflection surface that performs reciprocating rotational movement;
An imaging optical system that forms a two-dimensional image by moving the deflection-scanned light beams in the sub-scanning direction on the surface to be scanned;
By the control in which the forward path direction and the backward path direction of the plurality of light beams deflected and scanned in the two-dimensional image overlap in either the forward path direction or the backward path direction, Writing control means for eliminating overlap of imaging;
I have a,
The writing control means, when performing control in which the imaging in the forward direction by the plurality of light beams and the imaging in the backward direction by the plurality of light beams become substantially rectangular,
Based on the light emission timing of the light source means and the position of the image forming point included in the substantially rectangular shape, the arrangement order of the pixels of the two-dimensional image is set to one of the forward direction and the backward direction in the inclination correction process. On the other hand, an image forming apparatus characterized by performing rearrangement including a mirroring process that reverses the order of pixels . Deflection means for polarizing and scanning a plurality of light beams by a deflection surface that performs reciprocating rotational movement;
An imaging optical system that forms a two-dimensional image by moving the deflection-scanned light beams in the sub-scanning direction on the surface to be scanned;
By the control in which the forward path direction and the backward path direction of the plurality of light beams deflected and scanned in the two-dimensional image overlap in either the forward path direction or the backward path direction, Writing control means for eliminating overlap of imaging;
I have a,
The writing control means, when performing control in which the imaging in the forward direction by the plurality of light beams and the imaging in the backward direction by the plurality of light beams become substantially rectangular,
Based on the light emission timing of the light source means and the position of the image forming point included in the substantially rectangular shape, the arrangement order of the pixels of the two-dimensional image is set to one of the forward direction and the backward direction in the inclination correction process. On the other hand, the optical scanning device is characterized by performing rearrangement including a mirroring process for reversing the pixel arrangement order . A light source unit that emits the plurality of light beams to a deflecting unit that deflects and scans a plurality of light beams incident on an imaging optical system that forms a two-dimensional image in a substantially main scanning direction by a deflecting surface that performs reciprocal rotation; An integrated circuit for generating a control signal,
An input circuit for receiving a synchronization signal in the main scanning direction in the imaging optical system;
By the control in which the forward path direction and the backward path direction of the plurality of light beams deflected and scanned in the two-dimensional image overlap in either the forward path direction or the backward path direction, A control circuit for eliminating overlap of imaging,
I have a,
The control circuit, when performing control in which the imaging in the forward direction by the plurality of light beams and the imaging in the backward direction by the plurality of light beams are substantially rectangular,
Based on the light emission timing of the light source means and the position of the image forming point included in the substantially rectangular shape, the arrangement order of the pixels of the two-dimensional image is set to one of the forward direction and the backward direction in the inclination correction process. On the other hand, an integrated circuit characterized by performing rearrangement, including a mirroring process that reverses the order of pixels .