JP2008249980A - Optical scanning device, optical scanning method, image forming apparatus, color image forming apparatus, program, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical scanning device by which the sizes of images on both sides agree with each other when double-sided printing or the like is performed. <P>SOLUTION: The optical scanning device includes a light source driving control means 50 driving and controlling a plurality of light sources. The light source driving control means 50 drives and controls the plurality of light sources so that N light sources (N≥2) capable of scanning different positions in a sub scanning direction emit light and perform the scanning to form one pixel. When the subpixel corresponds to one light source, and one pixel is constituted of a plurality of sub pixels, the data of the subpixels are deleted in the sub scanning direction from the image data according to prescribed correction data to shift (reduce) the image data in the sub scanning direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical scanning device, an optical scanning method, an image forming apparatus, a color image forming apparatus, a program, and a recording medium.

  FIG. 17 is a diagram illustrating a configuration example of a general image forming apparatus such as a laser printer or a digital copying machine using an electrophotographic process. Referring to FIG. 17, laser light emitted from a semiconductor laser unit 1001 that is a light source unit is deflected and scanned by a rotating polygon mirror 1002 and is a scanned medium through a scanning lens (fθ lens) 1003. A light spot is formed on the photoconductor 1004, and the photoconductor 1004 is exposed to form an electrostatic latent image. At this time, the phase synchronization circuit 1009 sets the modulation signal generated by the clock generation circuit 1008 to a phase synchronized with the photodetector 1005 that detects the light of the semiconductor laser deflected and scanned by the polygon mirror 1002. In other words, the phase synchronization circuit 1009 generates a phase-synchronized image clock (pixel clock) for each line based on the output signal of the photodetector 1005 and supplies the image clock to the image processing unit 1006 and the laser drive circuit 1007. To do. In this way, the semiconductor laser unit 1001 performs the operation of the semiconductor laser via the laser driving circuit 1007 according to the image data generated by the image processing unit 1006 and the image clock whose phase is set for each line by the phase synchronization circuit 1009. By controlling the light emission time, the electrostatic latent image on the scanned medium (photoconductor) 1004 can be controlled.

  However, in recent years, there has been an increasing demand for higher printing speed (image forming speed) and higher image quality. On the other hand, higher polygon motors, which are deflectors, and higher pixel clocks, which serve as reference clocks for laser modulation. However, the speed limit of either method is approaching, and the conventional method cannot cope with it.

  Therefore, the use of a multi-beam using a plurality of light sources is used for speeding up. In the multi-beam optical scanning method, the number of light beams that can be simultaneously scanned by the deflection of the deflector increases, so that the rotational speed of the polygon motor, which is a deflector, and the pixel clock frequency can be reduced, and high-speed and stable optical scanning and Image formation is possible.

  As a light source constituting the multi-beam, a method of combining a single beam laser chip or a method of using an LD array in which a plurality of light emitting elements are incorporated in one laser chip is used.

  A semiconductor laser such as an LD array constituting the multi-beam is extremely small and can be directly modulated at a high speed by a driving current, so that it has been widely used as a light source for a laser printer or the like in recent years. However, since the relationship between the drive current of the semiconductor laser and the optical output has a characteristic that varies depending on the temperature, it becomes a problem when the light intensity of the semiconductor laser is set to a desired value. In particular, in the case of a surface emitting laser in which a plurality of light sources are configured on the same chip, the distance between the light sources is short, so that the effects of temperature change and temperature crosstalk due to light emission and extinction are significant, and the light quantity is likely to change.

  For example, in Patent Document 1, in an optical scanning device that scans a scanned medium by arranging a plurality of light sources in a two-dimensional manner and deflecting a plurality of light beams by a deflector, crosstalk caused by heat generation between light emitting points is disclosed. An example is shown in which the arrangement density of the light emitting points is maximized without causing an influence.

  Further, in Patent Document 2, in an image forming apparatus using a surface emitting laser, an electrostatic latent image of a pixel is obtained by having means for changing the light emission intensity of each chip and means for controlling the light emission time in units of pixels. The way to control is shown.

  Further, Patent Document 3 discloses a method for avoiding the problem of thermal stroke and realizing high density of recorded images by adopting a configuration in which the arrangement of light sources is defined in a scanning device using a surface emitting laser. It is shown.

JP 2001-272615 A JP 2003-72135 A JP 2001-350111 A

  By the way, when double-sided printing is performed by an image forming apparatus such as a copying machine, the paper is thermally contracted by the heat generated when one side (for example, the front side) is printed, and the other side (for example, the back side) is continuously printed. There is a problem that the image on the other side (for example, the back side) becomes larger.

  The present invention provides an optical scanning device, an optical scanning method, an image forming apparatus, a color image forming apparatus, a program, and a recording medium capable of matching the sizes of images on both sides, for example, in duplex printing. It is an object.

  In order to achieve the above object, the invention described in claim 1 is an optical scanning device that scans a plurality of light beams from a plurality of light sources in the main scanning direction. Drive control of a plurality of light sources so that one pixel is formed by emitting and scanning a light source of N ≧ 2), and it is assumed that a sub-pixel corresponds to one light source, and one pixel includes a plurality of sub-pixels. In the case of being constituted by pixels, sub-pixel data is deleted from the image data in the sub-scanning direction according to predetermined correction data, and the image data is shifted in the sub-scanning direction.

  According to a second aspect of the present invention, in the optical scanning device according to the first aspect, data for one row of subpixels is deleted from the image data in the subscanning direction, and the image data is shifted in the subscanning direction. It is said.

  According to a third aspect of the present invention, in the optical scanning device according to the first aspect, subpixel data is randomly deleted from the image data in the subscanning direction, and the image data is shifted in the subscanning direction. Yes.

  According to a fourth aspect of the present invention, in the optical scanning device according to the third aspect, only non-rendering data is randomly deleted from the image data as sub-pixel data in the sub-scanning direction, and the image data is shifted in the sub-scanning direction. It is characterized by letting.

  According to a fifth aspect of the present invention, in the optical scanning device according to the third aspect, only drawing data is randomly deleted from the image data as sub-pixel data in the sub-scanning direction, and the image data is shifted in the sub-scanning direction. It is characterized by that.

  According to a sixth aspect of the invention, in the optical scanning device according to the third aspect of the present invention, the optical scanning device has a function of switching between deletion of a sub-pixel of drawing data and deletion of a sub-pixel of non-drawing data from the image data. It is characterized by shifting in the sub-scanning direction.

  The invention according to claim 7 is the optical scanning device according to any one of claims 1 to 6, wherein the first printing is performed on one sheet, followed by the second printing. When printing is performed, the deletion of the sub-pixel data in the image data in the sub-scanning direction is performed at the time of the second printing.

  The invention according to claim 8 is the optical scanning device according to any one of claims 1 to 7, wherein a surface emitting laser is used as the light source.

  The invention according to claim 9 is an optical scanning method of scanning a plurality of light beams from a plurality of light sources in the main scanning direction, and N (N ≧ 2) light sources capable of scanning different positions in the sub-scanning direction. When driving control of a plurality of light sources is performed so that one pixel is formed by emitting light and scanning, and a sub-pixel corresponds to one light source, and one pixel is constituted by a plurality of sub-pixels In addition, according to predetermined correction data, subpixel data is deleted from the image data in the sub-scanning direction, and the image data is shifted in the sub-scanning direction.

  A tenth aspect of the present invention is an image forming apparatus including the optical scanning device according to any one of the first to eighth aspects.

  An eleventh aspect of the present invention is a color image forming apparatus comprising the optical scanning device according to any one of the first to eighth aspects.

  The invention according to claim 12 emits N (N ≧ 2) light sources capable of scanning different positions in the sub-scanning direction when scanning a plurality of light beams from a plurality of light sources in the main scanning direction. , A drive control of a plurality of light sources is performed so that one pixel is formed by scanning, and a sub pixel corresponds to one light source, and one pixel is constituted by a plurality of sub pixels. This is a program for causing a computer to implement processing for deleting subpixel data from image data in the sub-scanning direction according to predetermined correction data and shifting the image data in the sub-scanning direction.

  The invention according to claim 13 emits N (N ≧ 2) light sources capable of scanning different positions in the sub-scanning direction when scanning a plurality of light beams from a plurality of light sources in the main scanning direction. , A drive control of a plurality of light sources is performed so that one pixel is formed by scanning, and a sub pixel corresponds to one light source, and one pixel is constituted by a plurality of sub pixels. A computer-readable recording medium storing a program for causing a computer to execute processing for deleting subpixel data from image data in the sub-scanning direction according to predetermined correction data and shifting the image data in the sub-scanning direction is there.

  According to the first to twelfth aspects of the present invention, in an optical scanning device that scans a plurality of light beams from a plurality of light sources in the main scanning direction, N (N ≧) that can scan different positions in the sub-scanning direction. 2) Drive control of a plurality of light sources is performed so that one pixel is formed by emitting and scanning the light source, and it is assumed that a sub pixel corresponds to one light source, and one pixel is composed of a plurality of sub pixels. When configured, the subpixel data is deleted from the image data in the sub-scanning direction according to the predetermined correction data, the image data is shifted (reduced) in the sub-scanning direction, and the size of the image in the sub-scanning direction. By reducing the size of the image, for example, even when the paper is thermally contracted by the heat generated when one side is printed during double-sided printing, for example, the sizes of the images on both sides can be matched.

  In particular, according to the second aspect of the invention, in the optical scanning device according to the first aspect, the data for one row of subpixels is deleted from the image data in the sub-scanning direction, and the image data is shifted in the sub-scanning direction. Therefore, it can be realized with a simple configuration, and the amount of correction data can be kept small.

  According to a third aspect of the present invention, in the optical scanning device according to the first aspect, the subpixel data is randomly deleted from the image data in the subscanning direction, and the image data is shifted in the subscanning direction. In addition, by randomly scattering the sub-pixels to be deleted, it is possible to suppress the influence on the image when the image size is reduced in the sub-scanning direction.

  According to the fourth aspect of the present invention, when there is a large amount of non-rendering data in the entire image, it is possible to suppress the influence on the image to a small extent by randomly deleting only the sub-pixels of the non-rendering data. .

  According to the fifth aspect of the present invention, when there is a lot of drawing data in the entire image, it is possible to reduce the influence on the image by deleting only the sub-pixels of the drawing data at random.

  According to the invention described in claim 6, the image size can be adjusted in the sub-scanning direction with respect to various image patterns by having a function of switching the deletion of the sub-pixel of the drawing data and the deletion of the sub-pixel of the non-drawing data. It is possible to adapt the enlargement function while keeping the influence on the image small.

  According to the seventh aspect of the present invention, in the optical scanning device according to any one of the first to sixth aspects, the first printing is performed on one sheet, followed by 2 When the second printing is performed, the deletion of the sub-pixel data in the image data in the sub-scanning direction is performed at the time of the second printing, so even if the paper is shrunk by the first printing, the first printing and the second printing are performed. It is possible to prevent the problem of the size of the image from the second printing.

  Further, according to the invention described in claim 8, in the optical scanning device according to any one of claims 1 to 6, a surface emitting laser is used as the light source. Compared with the case of using a general semiconductor laser, the power consumption can be reduced, and the structure of the light source can be easily formed. Therefore, the structure of the light source unit can be simplified and the cost can be reduced. It becomes possible.

  Further, according to the invention described in claims 10 and 11, since the image forming apparatus includes the optical scanning device according to any one of claims 1 to 8, for example, double-sided printing or the like. Even when the paper is thermally contracted by the heat when one side is printed at the time, for example, the sizes of the images on both sides can be matched.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. In the present invention, one pixel is a pure pixel (for example, a 2400 dpi pixel means a pixel of about 10.6 μm square), and a plurality of pixels (for example, a dither matrix) It does not mean one pixel as a result of combining (4 × 4 pixels).

  FIG. 1 is a diagram showing a configuration example of an optical scanning device of the present invention. Referring to FIG. 1, an optical scanning device of the present invention (an optical scanning device that scans a plurality of light beams from a plurality of light sources in the main scanning direction) includes a light source drive control unit 50 that drives and controls a plurality of light sources. The light source drive control means 50 controls the drive of a plurality of light sources so that one pixel is formed by emitting and scanning N (N ≧ 2) light sources capable of scanning different positions in the sub-scanning direction. If the sub-pixel corresponds to one light source and one pixel is composed of a plurality of sub-pixels, the sub-pixel data is deleted from the image data in the sub-scanning direction according to predetermined correction data. The image data is shifted (reduced) in the sub-scanning direction.

  The optical scanning device of the present invention will be specifically described.

  Now, in the general image forming apparatus (writing optical system) in FIG. 17, a light source unit (semiconductor laser unit) 1001 has a plurality of light sources (a plurality of semiconductor lasers) arranged in a lattice pattern as shown in FIG. A semiconductor laser array (more specifically, for example, a surface emitting laser array in which a plurality of light sources (for example, a plurality of surface emitting lasers (VCSEL, surface emitting semiconductor laser)) are arranged in a lattice pattern on the same chip) Then, the arrangement and angle of the light source unit 1001 are adjusted so that the arrangement direction of the plurality of light sources has a certain angle θ with respect to the rotation axis of the deflector such as the polygon mirror in FIG.

  At this time, in FIG. 2, four light sources in the vertical arrangement direction a are light sources a1, a2, a3, a4 from the left, and two light sources a2, a3, for example, among these four light sources a1, a2, a3, a4. Consider a case where one pixel is formed by light emission and scanning (considering a case where one pixel is formed by one virtual light source array made of four light sources). When the pixel density to be formed is 600 dpi, the distance between the two light sources is equivalent to 2400 dpi, and the light source density is four times the pixel density. Therefore, in this case, for example, by changing the light quantity ratio of a plurality of light sources constituting one pixel, it becomes possible to shift the center of gravity position of the pixels in the sub-scanning direction, thereby realizing highly accurate pixel formation exceeding the light source density. it can.

  3A and 3B are diagrams for explaining the present invention. In general, when duplex printing is performed by an image forming apparatus such as a copying machine, as shown in FIG. 3A, heat is first applied by fixing when printing one surface (for example, the front surface). However, when the other side (for example, the back side) is printed, the image on the other side (for example, the back side) becomes larger. Therefore, in the present invention, as shown in FIG. 3B, after printing one surface (for example, the front surface) first, the image is reduced and printed when the other surface (for example, the back surface) is printed. To do. As a result, it is possible to correct the shrinkage of the paper and to match the sizes of the images on both sides. Note that, in a broader sense, the present invention is not limited to double-sided printing, and the present invention can be applied to a second printing when performing a first printing on a sheet of paper and a subsequent second printing. (I.e., in the second printing, the sub-pixel data is deleted from the image data in the sub-scanning direction so that the image is reduced and printed). Even if the paper is shrunk by printing, it is possible to prevent a problem with respect to the size of the image between the first printing and the second printing.

  Here, when scanning is performed by emitting a plurality of light sources (four light sources in the example of FIG. 2) for one pixel, there are the following advantages. That is, when a surface-emitting laser is used as the light source of the present invention, the output of the surface-emitting laser is weaker than that of a conventional laser, so that a sufficient amount of light for development cannot be obtained by scanning with one light source. There is sex. Therefore, in order to obtain a sufficient amount of light, it is preferable to perform scanning by causing a plurality of light sources to emit light for one pixel.

  FIG. 2 shows a case where three pixels are drawn simultaneously by 12 light sources, and one pixel is drawn by four light sources. Each pixel is composed of 4 × 4 sub-pixels, and drawing data and non-drawing data are given to the sub-pixels like the top pixel P1 of the three pixels P1, P2 and P3 in FIG. Thus, the lighting timing of the light source is set. The light source is turned on in the drawing data portion and turned off in the non-drawing data portion. The light emission of each light source in the drawing pattern of the uppermost pixel P1 in FIG. 2 is as light source lighting timing 1, and the whole is drawing data like the second and third pixels P2, P3 from the top. In the drawing pattern, light emission of each light source is as shown in light source lighting timing 2.

  4 to 8 are diagrams for explaining more specific examples of the present invention for reducing the size of the entire image in the sub-scanning direction.

  In the example of FIG. 4, the size of the entire image in the sub-scanning direction is reduced by deleting sub-pixels (sub-pixel data) smaller than one pixel in the sub-scanning direction at a plurality of locations line by line.

  In the example of FIG. 5, the positions at which sub-pixels are deleted (positions at which sub-pixel data is deleted) are randomly scattered in the sub-scanning direction. Although a 2 × 5 matrix is depicted in FIG. 5, the same processing is actually performed on the entire image as shown in FIG. In the examples of FIGS. 5 and 6, the positions of the sub-pixels to be deleted are random, but the image cannot be uneven by deleting the same number of sub-pixels from each column. In this way, by randomly scattering the positions where data is deleted, the influence on the image can be reduced compared to the case where data is deleted line by line as shown in FIG.

  In the example of FIG. 7, only non-drawing data (non-image data portion) is deleted as sub-pixel data. As in the example of FIG. 7, when there is a large amount of non-image data (non-drawn data) in the entire image to be drawn, the effect on the image is reduced by deleting the non-image data (sub-pixels of non-drawn data). .

  In the example of FIG. 8, only the drawing data (image data portion) is deleted as the sub-pixel data. As in the example of FIG. 8, when there is a lot of image data (drawing data) in the entire image to be drawn (in the example of FIG. 8, the image to be drawn is solid (the same color on the entire surface)), the image data ( The effect on the image is smaller when the subpixels of the drawing data are deleted.

  If there is a lot of drawing data around the subpixel to be deleted, the subpixel of the drawing data is deleted, while if there is a lot of nondrawing data around the subpixel to be deleted, the subpixel of the non-drawing data is deleted. Thus, if the function to switch the deletion of sub-pixels of drawing data and the deletion of sub-pixels of non-drawing data is provided, the effect on the image can be further reduced even when the image size in the sub-scanning direction is reduced. It can be reduced.

  FIG. 9 is a diagram showing a specific example of the light source drive control means 50 of the optical scanning device of the present invention. As shown in FIG. 9, the light source drive control unit 50 performs the first printing (for example, single-sided printing) when performing the first printing and the second printing such as double-sided printing. When the degree of heat shrinkage of the paper due to heat is given as correction data, sub-pixel data (drawing data or non-drawing data) illustrated in FIGS. 4 to 8 according to the correction data is obtained from the image data. It is supposed to be deleted.

  Here, the correction data is set in the following manner, for example. That is, for example, the amount of heat shrinkage is measured in advance for each printer model, and this is prepared as correction data, or each time printing is performed (the first sheet when printing multiple sheets) after single-sided printing. The size of the paper can be detected by a sensor or the like and set as correction data.

  FIG. 10 is a diagram showing an example of an image forming apparatus using the optical scanning device of the present invention. Referring to FIG. 10, on the back surface of the light source unit 801, a printed circuit board 802 on which a drive circuit for controlling a semiconductor laser and a pixel clock generator is formed is mounted, and a spring is attached to the wall surface of the optical housing orthogonal to the optical axis. The contact is made, and the inclination is adjusted by the adjusting screw 803 to maintain the posture. The adjusting screw 803 is screwed into a protrusion formed on the wall surface of the housing. Inside the optical housing, a cylinder lens 805, a polygon motor 808 that rotates a polygon mirror, an fθ lens 806, a toroidal lens, and a folding mirror 807 are positioned and supported, respectively, and a printed circuit board 809 on which a synchronization detection sensor is mounted includes: Like the light source unit, it is mounted on the housing wall from the outside. The upper portion of the optical housing is sealed by a cover 811 and is screwed to the frame member of the image forming apparatus main body by a plurality of mounting portions 810 protruding from the wall surface.

  At this time, a semiconductor laser array (specifically, for example, a surface emitting laser (surface emitting laser array)) having a plurality of light sources as shown in FIG. 2 can be used for the light source unit 801 as a semiconductor laser. Light emitted from the semiconductor laser (surface emitting laser) of the light source unit 801 is deflected and scanned along with the rotation of the polygon mirror via the cylinder lens 805, and the deflected and scanned light flux includes an fθ lens 806, a toroidal lens, and The light enters a photosensitive drum (not shown) via a folding mirror 807 and the like. Further, the scanning light is detected by the sensor as a region not scanned by the photosensitive member or reflected light from a mirror or the like. As a signal detected by the sensor at this time, a time interval between two points in the main scanning direction, which is the scanning direction associated with the rotation of the polygon mirror, is detected by a synchronous detection sensor, or a direction rotated 90 degrees with respect to the main scanning direction The pixel position can be corrected by measuring the amount of misalignment in the sub-scanning direction with a position detection sensor and performing feedback control of the value to the LD control and the modulation circuit or the preceding modulation data generation unit. .

  Next, a multi-beam scanning device (multi-beam optical system) configured using a plurality of light sources will be described.

  FIG. 11 is a diagram illustrating an example of a multi-beam scanning device. In the example of FIG. 11, two (301, 302) semiconductor laser arrays (four channels) in which two light emitting sources are monolithically arranged at an interval ds = 25 μm are used (8 light sources are used).

  In FIG. 11, the semiconductor laser arrays 301 and 302 have the same optical axis as that of the collimating lenses 303 and 304, have an emission angle symmetrical to the main scanning direction, and the emission axes intersect at the reflection point of the polygon mirror 307. It is laid out. A plurality of beams emitted from the respective semiconductor laser arrays 301 and 302 are collectively scanned by a polygon mirror 307 through a cylinder lens 308 and imaged on a photoconductor 312 by an fθ lens 310 and a toroidal lens 311. In the buffer memory, print data for one line is stored in each light source, read out for each surface of the polygon mirror, and recording is performed on four lines simultaneously.

  In addition, in order to correct the optical scanning length difference and magnification difference caused by the wavelength error for each LD constituting the multi-beam, the phase shift is performed on the pixel clock, so that the scanning length difference is reduced to the phase shift accuracy. Can be corrected, and variations in scanning light can be reduced.

  FIG. 12 shows an example in which a two-dimensional surface-emitting laser array in which a plurality of surface-emitting lasers are arranged in a two-dimensional array is used for a light source unit of an optical scanning device. In the example of FIG. 12, a two-dimensional surface emitting laser array having a total of 12 light emitting sources (surface emitting lasers), 3 in the horizontal direction and 4 in the vertical direction, is shown.

  Next, a multi-beam scanning device (multi-beam optical system) using a surface emitting laser array (VCSEL array) as a light source unit will be described. FIG. 13 is a diagram showing an example of a multi-beam scanning device using a VCSEL array as a light source unit. In the example of FIG. 13, the two light emitting sources 301 and 302 of FIG. 11 are replaced with one VCSEL array 402.

  In FIG. 13, a plurality of light beams emitted from the VCSEL array 402 are collectively scanned by a polygon mirror 407 via a collimator lens 404 and a cylinder lens 408, and a photosensitive surface which is a scanned surface by an fθ lens 410 and a toroidal lens 411. An image is formed on the body 412. In the buffer memory, print data for one line is stored in each light emitting source, read out for each surface of the polygon mirror, and recording is performed for a plurality of lines simultaneously. In addition, in order to correct the optical scanning length difference and magnification difference caused by the wavelength error for each surface emitting laser constituting the multi-beam, the phase shift is performed on the pixel clock, so that the scanning length is reduced to the phase shift accuracy. It is possible to correct the difference in height and reduce variations in scanning light.

  FIG. 14 is a diagram showing a configuration example of the image forming apparatus of the present invention. Referring to FIG. 14, a charged charger 902 for charging the photosensitive member to a high voltage and a toner charged to the electrostatic latent image recorded by the optical scanning device 900 are attached around the photosensitive drum 901 which is a surface to be scanned. A developing roller 903 that visualizes the toner, a toner cartridge 904 that supplies toner to the developing roller 903, and a cleaning case 905 that scrapes and stores toner remaining on the drum 901 are disposed. As described above, a plurality of lines are simultaneously recorded on the photosensitive drum 901 for each surface. The recording paper is supplied from the paper supply tray 906 by the paper supply roller 907, is sent out by the registration roller pair 908 in accordance with the recording start timing in the sub-scanning direction, and is transferred to the toner by the transfer charger 906 when passing through the photosensitive drum 901. Is transferred, fixed by the fixing roller 909, and discharged to the paper discharge tray 910 by the paper discharge roller 912. By applying the optical scanning device of the present invention to the optical scanning device 900 of the image forming apparatus, dot position correction with high accuracy becomes possible, and a high-quality image can be obtained.

  The present invention is also applicable to a color image forming apparatus. FIG. 15 shows an example in which the present invention is mounted on a tandem color machine which is an image forming apparatus having a plurality of photoconductors. The tandem color machine requires separate photoconductors corresponding to cyan, magenta, yellow, and black colors, and the optical scanning optical system forms latent images through different optical paths corresponding to the photoconductors. . Therefore, the main scanning dot position shift generated on each photoconductor often has different characteristics.

  In FIG. 15, 18 is a transfer belt, 19a, 19b, 19c and 19d are photoconductors corresponding to the respective colors, and 20a, 20b, 20c and 20d are optical scanning devices corresponding to the respective colors.

  Here, by using the optical scanning device of the present invention for the optical scanning devices 20a, 20b, 20c, and 20d, for example, even when the paper is thermally contracted by heat when one side is printed at the time of double-sided printing or the like, For example, the sizes of the images on both sides can be matched.

  FIG. 16 is a diagram showing a hardware configuration example of the light source drive control means 50 of the optical scanning device of the present invention. In this example, the light source drive control means 50 includes a CPU 101, a ROM 102, a RAM 103, an HDD (hard disk drive) 104, an HD (hard disk) 105, an FDD (flexible disk drive) 106, etc. connected by a bus 100.

  The CPU 101 controls the entire apparatus. The ROM 102 stores a control program. The RAM 103 is used as a work area for the CPU 101. The HDD 104 controls data read / write with respect to the HD 105 according to the control of the CPU 101. The HD 105 stores data written according to the control of the HDD 104. The FDD 106 performs data read / write control with respect to the FD (flexible disk) 107 in accordance with the control of the CPU 101. The FD 107 is detachable and stores data written according to the control of the FDD 106.

  Note that the processing in the light source drive control means 50 described in the above-described best mode for carrying out the present invention can be provided in the form of a program realized by a computer (for example, the CPU 101).

  A program for causing a computer to execute the processing in the light source drive control means 50 described in the above-described best mode for carrying out the present invention includes a hard disk (105), a floppy (registered trademark) disk, a CD-ROM, The program is recorded on a computer-readable recording medium such as MO and DVD, and is executed by being read from the recording medium by the computer. Further, this program can be distributed via a network such as the Internet through the recording medium.

The present invention can be used in laser printers, digital copying machines, and the like.

It is a figure which shows the structural example of the optical scanning device of this invention. It is a figure which shows an example of a light source unit. It is a figure for demonstrating this invention. It is a figure for demonstrating the specific example of this invention. It is a figure for demonstrating the specific example of this invention. It is a figure for demonstrating the specific example of this invention. It is a figure for demonstrating the specific example of this invention. It is a figure for demonstrating the specific example of this invention. It is a figure which shows the structural example of the optical scanning device of this invention. It is a figure which shows an example of the image forming apparatus using the optical scanning device of this invention. It is a figure which shows an example of a multi-beam scanning apparatus. It is a figure which shows an example of a light source unit. It is a figure which shows an example of a multi-beam scanning apparatus. 1 is a diagram illustrating a configuration example of an image forming apparatus of the present invention. 1 is a diagram illustrating an example of a color image forming apparatus. It is a figure which shows the hardware structural example of the light source drive control means of the optical scanning device of this invention. 1 is a diagram illustrating a configuration example of a general image forming apparatus.

Explanation of symbols

50 Light source drive control means 1001 Light source unit 100 Bus 101 CPU
102 ROM
103 RAM
104 HDD (Hard Disk Drive)
105 HD (hard disk)
106 FDD (flexible disk drive)
107 FD (flexible disc)

Claims (13)

In an optical scanning device that scans a plurality of light beams from a plurality of light sources in the main scanning direction, one pixel is formed by emitting and scanning N (N ≧ 2) light sources capable of scanning different positions in the sub-scanning direction. In the case where a plurality of light sources are controlled to be formed, and a sub-pixel corresponds to one light source, and one pixel is composed of a plurality of sub-pixels, an image is generated according to predetermined correction data. An optical scanning device characterized by adding subpixel data to data in the sub-scanning direction and shifting image data in the sub-scanning direction. 2. The optical scanning device according to claim 1, wherein data for one row of subpixels is added to the image data in the sub-scanning direction, and the image data is shifted in the sub-scanning direction. 2. The optical scanning device according to claim 1, wherein sub-pixel data is randomly added to the image data in the sub-scanning direction, and the image data is shifted in the sub-scanning direction. 4. The optical scanning device according to claim 3, wherein only non-drawing data is randomly added to the image data as sub-pixel data in the sub-scanning direction, and the image data is shifted in the sub-scanning direction. 4. The optical scanning device according to claim 3, wherein only drawing data is randomly added to the image data as sub-pixel data in the sub-scanning direction, and the image data is shifted in the sub-scanning direction. 4. The optical scanning device according to claim 3, wherein the optical scanning device has a function of switching between addition of a sub-pixel of drawing data and addition of a sub-pixel of non-drawing data to image data, and shifts the image data in the sub-scanning direction. Optical scanning device. The optical scanning device according to any one of claims 1 to 6, wherein when the first printing is performed on one sheet of paper and the second printing is subsequently performed, the image data is converted into image data. The optical scanning device characterized in that the sub-pixel data is added in the sub-scanning direction at the first printing. 8. The optical scanning device according to claim 1, wherein a surface emitting laser is used as the light source. In an optical scanning method of scanning a plurality of light beams from a plurality of light sources in the main scanning direction, one pixel is formed by emitting and scanning N (N ≧ 2) light sources capable of scanning different positions in the sub-scanning direction. In the case where a plurality of light sources are driven and controlled so that a sub-pixel corresponds to one light source, and one pixel is composed of a plurality of sub-pixels, an image corresponding to predetermined correction data is formed. An optical scanning method characterized by adding subpixel data to data in the sub-scanning direction and shifting image data in the sub-scanning direction. An image forming apparatus comprising the optical scanning device according to claim 1. A color image forming apparatus comprising the optical scanning device according to claim 1. When scanning a plurality of light beams from a plurality of light sources in the main scanning direction, one pixel is formed by emitting and scanning N (N ≧ 2) light sources capable of scanning different positions in the sub-scanning direction. As described above, when drive control of a plurality of light sources is performed and a sub-pixel corresponds to one light source, and one pixel is composed of a plurality of sub-pixels, image data is generated according to predetermined correction data. A program for causing a computer to implement processing for adding subpixel data in the subscanning direction and shifting image data in the subscanning direction. When scanning a plurality of light beams from a plurality of light sources in the main scanning direction, one pixel is formed by emitting and scanning N (N ≧ 2) light sources capable of scanning different positions in the sub-scanning direction. As described above, when drive control of a plurality of light sources is performed and a sub-pixel corresponds to one light source, and one pixel is composed of a plurality of sub-pixels, image data is generated according to predetermined correction data. A computer-readable recording medium on which a program for causing a computer to execute processing for adding subpixel data in the subscanning direction and shifting image data in the subscanning direction is recorded.

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