JP5614194B2 - Image forming apparatus, image forming method, program, and recording medium - Google Patents

Description

  The present invention relates to an image forming apparatus, an image forming method, a program, and a recording medium that do not deteriorate image quality due to insertion and deletion of pixels.

  When performing double-sided printing in an electrophotographic process type image forming apparatus that uses multi-beams for optical scanning, a system is used in which the first side of the paper is recorded, heat-fixed, and then the second side is recorded. Therefore, for example, a magnification difference of 0.2% to 0.4% occurs between the printing on the first surface and the printing on the second surface. This occurs due to the loss of moisture from the paper, and the magnification difference varies depending on the type of paper.

  Therefore, there is a technique for performing correction such as pixel thinning and pixel insertion for magnification adjustment and bending correction (see, for example, Patent Documents 1 and 2).

  However, in the above-described pixel insertion / deletion method, when the resolution of the image forming apparatus is improved, the pixel insertion / deletion distance becomes short. FIG. 18A shows low-resolution insertion / deletion, and FIG. 18B shows high-resolution insertion / deletion. At this time, if the beam diameter itself becomes smaller in accordance with the improvement in resolution, there is no problem. However, in practice, the beam diameter does not become smaller. There was a problem of deterioration.

  That is, the change in the amount of toner adhering to the region due to insertion / deletion becomes a streak. There is a non-linear relationship between the toner adhesion and the exposure amount. As shown in FIG. 19, if the insertion / deletion pixels are close and continuous, the combined energy exceeds the threshold value for toner adhesion. If so, the toner adheres to the area exceeding the threshold. As a result, black stripes are generated obliquely.

  FIG. 20 is a diagram for explaining a conventional pixel insertion process. For example, FIG. 20A shows an original image, and when a pixel is added at a rate of 1 pixel per 200 pixels in the sub-scanning direction, a magnification of about 0.5% can be realized (FIG. 20B). As described above, even if the pixels are inserted and deleted, the distortion of the image does not occur because the distances between the distortions arranged in the oblique direction are separated. At this time, this scaling does not depend on the resolution of the image output apparatus. Here, in order to obtain a higher-function output device, it is assumed that the resolution of the writing system is improved as shown in FIG.

  By the way, since the ratio of one pixel to 200 pixels is not affected by the resolution of the writing system, it is necessary to add pixels at a ratio of one pixel of 200 pixels in order to realize a zoom ratio of 0.5%. . That is, as shown in FIG. 20C, the actual distance of the insertion / deletion position in the oblique direction is reduced. The reason why the streak does not occur in the image by simple pixel insertion / deletion is because the interval of insertion / deletion is far away. Will occur.

  Therefore, for example, if one pixel is set to 400 pixels, the problem does not occur as in the conventional case, but instead, only a magnification of about 0.25% can be realized. In other words, streaks occur in the image at a zoom ratio of 0.5%, which has no problem with the conventional image quality.

The present invention has been made in view of the above-described problems.
SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus in which the resolution of the image forming apparatus is improved by pixel insertion / deletion, and image quality deterioration (streak) does not occur due to insertion / deletion even when the pixel insertion / deletion distance is short An object is to provide an image forming method, a program, and a recording medium.

The present invention
Image forming means for exposing in accordance with an image signal and forming an image by an electrophotographic process, and image correction for enlarging or reducing the image by regularly inserting or deleting pixels (hereinafter referred to as insertion / deletion) to the image In an image forming apparatus provided with a means,
The image correcting means includes a setting means for setting insertion / deletion pixel positions in the main scanning direction and the sub-scanning direction, a frequency dividing means for dividing the main scanning clock, and a first count for counting the outputs of the frequency dividing means. Means for determining whether or not the count value of the second count means is the insertion / deletion pixel position in the set sub-scanning direction; As a result of the determination, when the insertion / deletion pixel position is in the set sub-scanning direction, the main scanning corresponding to the insertion / deletion pixel position in the main scanning direction is based on the count result of the first counting means. said image correction means comprises output means for outputting the insertion deletion signal of the clock, the the insertion deleted pixel group by the plurality of insertion deletion pixels are located adjacent Produced, be arranged to the exposure area between the insertion deletion pixel group do not overlap, characterized by.

  According to the present invention, even when the resolution of the writing system is improved and the distance of insertion / deletion of pixels is reduced, an insertion / deletion pixel group is generated by arranging a plurality of insertion / deletion pixels to be adjacent to each other. Since the exposure area of the deleted pixel group is arranged so that they do not overlap, the combined energy of exposure at the insertion and deletion location by the beam will be discontinuous, and the image quality will be degraded (black and white streaks missing). Occurrence is avoided.

1 shows a configuration of an image forming apparatus of the present invention. The structure of a surface emitting semiconductor laser is shown. 1 shows a configuration in which an optical device exposes a photosensitive drum. It is a figure explaining the scanning position of interlaced scanning. The details of the exposure position on the photoreceptor are shown. 1 shows a configuration of a control unit of an image forming apparatus. The detailed structure of GAVD is shown. It is a figure explaining generation | occurrence | production of the malfunction when the resolution is raised. It is a figure explaining the process which eliminates generation | occurrence | production of the malfunction of FIG. The arrangement of the insertion / deletion pixel group of the present invention is shown. It is a figure explaining the reason which becomes difficult to generate | occur | produce a stripe | line by this invention. The other arrangement | positioning of the insertion deletion pixel group of this invention is shown. It is a figure explaining the insertion process of the pixel group of this invention. It is a figure explaining the insertion process of this invention in detail. It is a figure explaining the deletion of the pixel group of this invention in detail. An example of an insertion / deletion occurrence pattern corresponding to FIG. 12 is shown. 1 shows a configuration of an insertion / deletion signal generation circuit. Indicates low-resolution, high-resolution insertion / deletion. The synthetic energy by the conventional insertion deletion process is shown. It is a figure explaining the conventional pixel insertion process.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In an image processing apparatus that enlarges or reduces an image by regularly inserting or deleting pixels, the present invention collects insertion / deletion pixels to form an insertion / deletion pixel group. Place them so that they do not overlap.

  FIG. 1 shows a configuration of an image forming apparatus of the present invention. The image forming apparatus 100 includes an optical device 102 including optical elements such as a polygon mirror 102a, an image forming unit 112 including a photosensitive drum, a charging device, and a developing device, and a transfer unit 122 including an intermediate transfer belt. The The optical device 102 includes a VCSEL 200 (see FIGS. 2 and 3) (not shown) as a semiconductor laser. In the example shown in FIG. 1, the light beam emitted from the VCSEL 200 is once condensed by a first cylindrical lens (not shown) and deflected by the polygon mirror 102a to the reflection mirror 102b.

  The VCSEL (Vertical Cavity Surface Emitting Laser) 200 is a surface emitting semiconductor laser in which a plurality of light sources (semiconductor lasers) are arranged in a lattice pattern on the same chip. There are various techniques as an image forming apparatus using the VCSEL 200, and the VCSEL 200 is incorporated in the optical device 102 of the image forming apparatus 100 of the present invention with the same configuration as those known techniques.

  FIG. 2 shows a configuration of the VCSEL 200 incorporated in the optical device 102. As shown in FIG. 2, the VCSEL 200 constitutes a surface-emitting type semiconductor laser array in which a plurality of light sources ch1 to ch40 (a plurality of light emitting points) are arranged in an oblique lattice shape.

  The image forming apparatus 100 constitutes a post-object type optical device 102 that does not use an fθ lens. In the illustrated embodiment, light beams L composed of ch1 to ch40 are generated in a number corresponding to each color of cyan (C), magenta (M), yellow (Y), and black (K), and the polygon mirror 102a. The beam L deflected by the laser beam is reflected by the reflection mirror 102b and condensed again by the second cylindrical lens 102c to expose the photosensitive drums 104a, 106a, 108a, and 110a.

  Since the irradiation of the light beam L is performed using a plurality of optical elements as described above, the timings in the main scanning direction and the sub-scanning direction are synchronized. Hereinafter, the main scanning direction is defined as the scanning direction of the light beam, and the sub-scanning direction is defined as a direction orthogonal to the main scanning direction.

  Each of the photosensitive drums 104a, 106a, 108a, and 110a includes a photoconductive layer including at least a charge generation layer and a charge transport layer on a conductive drum such as aluminum. The photoconductive layers are disposed corresponding to the photosensitive drums 104a, 106a, 108a, and 110a, respectively, and surface charges are imparted by the chargers 104b, 106b, 108b, and 110b including a corotron, a scorotron, or a charging roller. Is done.

  The electrostatic charges imparted on the photosensitive drums 104a, 106a, 108a, 110a by the respective chargers 104b, 106b, 108b, 110b are imagewise exposed by the light beam L to form an electrostatic latent image. The electrostatic latent images formed on the photoconductive drums 104a, 106a, 108a, and 110a are developed by the developing devices 104c, 106c, 108c, and 110c including a developing sleeve, a developer supplying roller, a regulating blade, and the like. Is formed.

  The developer carried on the photosensitive drums 104a, 106a, 108a, and 110a is transferred onto the intermediate transfer belt 114 that moves in the direction of arrow A by the conveying rollers 114a, 114b, and 114c. The intermediate transfer belt 114 is conveyed to the secondary transfer unit while carrying C, M, Y, and K developers. The secondary transfer unit includes a secondary transfer belt 118 and conveying rollers 118a and 118b. The secondary transfer belt 118 is conveyed in the direction of arrow B by the conveyance rollers 118a and 118b. An image receiving material 124 such as high-quality paper or a plastic sheet is supplied to the secondary transfer portion from an image receiving material storage portion 128 such as a paper feed cassette by a conveying roller 126.

  The secondary transfer unit applies a secondary transfer bias to transfer the multicolor developer image carried on the intermediate transfer belt 114 onto the image receiving material 124 held by suction on the secondary transfer belt 118. The image receiving material 124 is supplied to the fixing device 120 along with the conveyance of the secondary transfer belt 118. The fixing device 120 includes a fixing member 130 such as a fixing roller including silicone rubber, fluorine rubber, and the like, pressurizes and heats the image receiving material 124 and the multicolor developer image, and outputs the printed material 132 to the outside of the image forming apparatus 100. Discharge. A reading sensor 133 for inspecting an image of the printed matter 132 is arranged at the discharge port, and the finished printed matter 132 is read. After the multicolor developer image is transferred, the transfer belt 114 is supplied to the next image forming process after the transfer residual developer is removed by the cleaning unit 116 including a cleaning blade.

  FIG. 3 shows a configuration in which the optical device 102 including the VCSEL 200 exposes the photosensitive drum 104a. The light beam L emitted from the VCSEL 200 is collected by the first cylindrical lens 202 used for shaping the light beam bundle, passes through the reflection mirror 204 and the imaging lens 206, and is then deflected by the polygon mirror 102a. . The polygon mirror 102a is rotationally driven by a spindle motor that rotates several thousand to several tens of thousands. The light beam L reflected by the polygon mirror 102a is reflected by the reflection mirror 102b and then reshaped by the second cylindrical lens 102c to expose the surface of the photosensitive drum 104a.

  In order to synchronize the scanning start timing of the light beam L in the sub-scanning direction, a reflection mirror 208 is disposed. The reflection mirror 208 reflects the light beam L to the synchronization detection device 210 including a photodiode or the like before starting scanning in the sub-scanning direction. When detecting the light beam, the synchronization detection device 210 generates a synchronization signal to start sub-scanning, and synchronizes processing such as generation of a drive control signal to the VCSEL 200.

  The VCSEL 200 is driven by a pulse signal sent from a GAVD 310, which will be described later. As will be described later, the light beam L is exposed at a position corresponding to a predetermined image bit of the image data, and an electrostatic latent image is formed on the photosensitive drum 104a. Form.

  FIG. 4 is a diagram for explaining the scanning position at which interlaced scanning is performed on the photosensitive member by the light beam L consisting of 40 beams of ch1 to ch40. The 40 light beams are collectively scanned in the main scanning direction by a polygon mirror. The 40 beams are scanned so as to skip over the scanning lines. FIG. 4 shows how 40 beams are scanned by five polygon mirrors.

  FIG. 5 shows the details of the exposure position on the photoreceptor. The exposure resolution on the photoconductor is 4800 dpi, and therefore, the interval between the pixels (squares) in FIG. 5 is about 5.2 μm. A scan S1 at a certain time point and a scan S2 by the next polygon mirror surface will be described. First, the polygon mirror surface scans 40 beams at a time. The beam is 40 channels, and the 20th channel (ch20) and 21st channel (ch21) in the center are close to each other. Between the other channels, a positional relationship is formed such that a gap of one scanning line is formed and scanning is performed in the main scanning direction.

  The position of the intermediate point a between the channel 20 and the channel 21 is the center of the lens group in the sub-scanning direction and is symmetric in the sub-scanning direction. When horizontal scanning is performed in such a positional relationship on a certain polygonal surface, the line indicated by S2 in the figure is scanned on the next surface, and the 21 channel (ch21) and 22 channel (ch22) of the S1 line are scanned. The gap is now scanned by one channel (ch1). The same applies to Y, C, and M. In this way, a writing unit with 4800 dpi resolution is configured.

  Such an interlaced scanning optical system consisting of 40 beams as a whole, and can be interpolated by a multiple of 8 because the central 20-21ch is close. The ability to process at a multiple of 8 makes it easier to handle even when configuring a circuit for image processing. In addition, when a VCSEL (surface emitting laser diode) is used as the light source, there is an advantage that the degree of freedom of light source arrangement is high. In addition, the sub-scanning beam interval between 1ch and 40ch is narrower than normal interlaced scanning, and the outermost beam is not so far away from the optical axis. Therefore, there are variations in sub-scanning beam pitch and beam spot diameter. Can be reduced. Further, there is an advantage that the effective range of the scanning lens can be reduced and the optical element can be miniaturized.

  FIG. 6 shows the configuration of the control unit 300 of the image forming apparatus 100. The control unit 300 is configured as a scanner unit 302, a printer unit 308, and a main control unit 330. The scanner unit 302 functions as a means for reading an image. A VPU 304 that performs A / D conversion on a signal read by the scanner to perform black offset correction, shading correction, and pixel position correction, and an acquired image as an RGB table. The IPU 306 performs image processing for digital conversion from color system to CMYK color system image data. The read image acquired by the scanner unit 302 is sent to the printer unit 308 as digital data.

  The printer unit 308 includes a gate array for video device (GAVD) 310 that functions as a control unit that performs drive control of the VCSEL 200, and a current for driving the semiconductor laser element by a drive control signal generated by the GAVD 310 to the semiconductor laser element. A supply LD driver 312 to be provided and a VCSEL 200 on which a two-dimensionally arranged semiconductor laser element is mounted. The GAVD 310 of this embodiment corresponds to the spatial arrangement on the photosensitive body of the semiconductor laser element emitted from the VCSEL 200 by using the image data sent from the scanner unit 302 or generated by a command or the like from the computer 327 side. The resolution is increased and the resolution is increased.

  The scanner unit 302 and the printer unit 308 are connected to the main control unit 330 via the system bus 316, and image reading and image formation are controlled by commands from the main control unit 330. The main control unit 330 includes a central processing unit (hereinafter referred to as CPU) 320 and a RAM 322 used by the CPU 320. An operation unit 329 and a computer 327 are connected to the interface 328 unit. The CPU 320 receives a command from the user via the interface 328, calls a program module that executes processing corresponding to the command, and executes processing such as copy, scanner, image storage, and printing. Further, the main control unit 330 includes a ROM 324 and stores initial setting data, control data, programs, and the like of the CPU 320. The image storage 326 is configured as a fixed or detachable memory device such as a hard disk device or a memory card, and stores image data acquired by the image forming apparatus 100 and image data transmitted from the external computer 327, so that various types of user data can be stored. It is made available for processing.

  The operation unit 329 is used for an operator to instruct a shift amount when performing an image shift described later. By instructing with the magnification% for designating the enlargement amount and reduction amount realized by the shift, the register setting information corresponding to the shift amount stored in the ROM 324 is read and set in the RAM 322. Alternatively, the parameters set in the register by the operator may be directly specified.

  When the printer unit 308 is driven for the image data acquired by the scanner unit 302 to output an image as an electrostatic latent image on the photosensitive drum 104a or the like, the CPU 320 performs main scanning and sub-scanning of an image receiving material such as fine paper or plastic film. Position control in the scanning direction is executed. The CPU 320 outputs a start signal to the GAVD 310 when starting scanning in the sub-scanning direction. When the GAVD 310 receives the start signal, the IPU 306 starts the scanning process. Thereafter, the GAVD 310 receives the image data stored in the buffer memory or the like, thereafter processes the received image data, and outputs the processed image data to the LD driver 312. Further, when outputting an image image or the like from the external computer 327, the image data and command code are accumulated in the RAM 322 and the image storage 326 without operating the scanner unit 302, and a start signal is output to the GAVD 310. Thereafter, the GAVD 310 screen-processes the image data stored in the buffer memory or the like, and outputs the processed image data to the LD driver 312.

  In the screen processing, an 8-bit image corresponding to an input image or an input command is compared with a predetermined threshold value table and converted into 1-bit image data of 0 or 1, or a specific corresponding to the input command Fill with an image pattern or texture. Alternatively, if the output of each beam of the VCSEL 200 has a capability of about 2 to 4 bits, it is converted into a corresponding 2 to 4 bit code. As a result, the image is converted into a binary or small value image having a screen angle. In the case of screen processing that forms random halftone dots having no screen angle, the image has no screen angle.

  When the LD driver 312 receives image data from the GAVD 310, the LD driver 312 generates a drive control signal for the VCSEL 200. Thereafter, the LD driver 312 sends the drive control signal to the VCSEL 200, thereby turning on the VCSEL 200. The LD driver 312 drives the semiconductor laser element using PWM control or the like. The VCSEL 200 of this embodiment includes 40 channels of semiconductor laser elements, but the number of channels of the VCSEL 200 is not limited to this.

  FIG. 7 shows a detailed configuration of the GAVD 310. The GAVD 310 includes a memory 340 such as a FIFO buffer that receives the synchronization signal and stores and stores the image data sent from the IPU 306, and corrects the image data transmitted from the IPU 306 in a first-in / first-out manner. Part 342. In addition, image data received from the interface 328 and image data generated by screen processing of commands are also stored in the memory 340.

  The image correction unit 342 reads the screen-processed image data from the memory 340, and adds and deletes correction pixels for changing the magnification by shifting the image bits, that is, the image data in the sub-scanning direction, and the image. Data correction processing in the sub-scanning direction is executed.

  The output data control unit 344 assigns output data serving as a write signal corresponding to the image data generated by the image correction unit 342 to the channel of the semiconductor laser element, and further provides synchronization for providing a synchronization signal to the synchronization detection device 210. Generate by adding a control signal. The generated drive control signal is transmitted to the LD driver 312, where the logic signal is converted into a current signal for driving the VCSEL to drive the VCSEL. The output data control unit 344 receives a synchronization signal from the synchronization detection device 210 and synchronizes transmission of the drive control signal to the LD driver 312. The processing of the memory 340, the image correction unit 342, and the output data control unit 344 is synchronized with the operation clock by the PLL 346.

  FIG. 8 is a diagram for explaining the occurrence of a problem when the resolution is increased. A square P (P11 to P13, P3 to P5, etc.) in FIG. 8 indicates a pixel position for insertion / deletion. The insertion / deletion positions are arranged obliquely in this way. The frequency of insertion / deletion in the sub-scanning direction, that is, the number of pixels corresponding to the distance A indicates a scaling factor due to pixel shift.

  The quadrangle P is generated by repeating an oblique portion surrounded by P11, P5, P4, and P3. At this time, the distance between P11 and P12 decreases as the resolution increases, that is, as the pixel size decreases. At this time, the condensing of the beam by the lens is not necessarily proportional to the improvement in resolution, and therefore, as shown in FIG. 8D, overlap (the exposure area of D continues) is started. For this reason, when a black pixel is placed, for example, when the pixel is inserted, this appears as a black stripe. In particular, it becomes prominent at intermediate levels of density. Alternatively, when a white pixel is set by inserting a pixel, this appears as a white streak.

  FIG. 9 shows the arrangement of insertion / deletion pixels when the distance between P11 and P12 is increased while the distance A is substantially maintained as a countermeasure. At this time, the distance C between P11 and P3 is now close, and for example, black stripes and white stripes tend to stand out in the horizontal direction. In the lateral direction, banding or the like is likely to occur in the electrophotographic engine. Therefore, simply maintaining the same distance as the distance between P11 and P12 makes the banding manifest in combination with the existing conventional banding. Therefore, a good result cannot be obtained by simply increasing the distance between P11 and P12.

  That is, if the distance between P11 and P12 is increased while the distance C is maintained, the distance A must be increased. The distance A determines the scaling factor by the shift. For example, if 200 pixels are used, 0.5% can be realized at 1/200. However, if the distance A is 400 pixels, it becomes 0.25%, and 0 .5% scaling cannot be realized, and the possible range of scaling is narrowed, which is not preferable. In the case of realizing a zoom ratio of 0.5%, the pixel distance is too close, and streaks occur in the image, which is not preferable.

  FIG. 10 shows the arrangement of the insertion / deletion pixel group of the present invention. As shown in FIG. 10, P12 and P13 are not generated at the positions P12 'and P13', but are arranged adjacent to each other in the main scanning direction of P11 to form a small group. As a result, in FIG. 10, the continuous portion of D is separated by a distance that does not cause overlapping of the exposure regions between the small groups, such as D1, D2, and D3, and the exposure regions are not continuous for each group. Therefore, as will be described later, in FIG. 8, the streak that has occurred obliquely does not occur. Note that the number of pixels constituting the small group needs to be set to an appropriate number according to the electrophotographic engine.

  FIG. 11 is a diagram for explaining the reason why it is difficult for the present invention to generate streaks. For example, a case where a black pixel is inserted will be described. As described above, when the exposure areas of the inserted pixels overlap as in the exposure circle of D of FIG. 8, the combined energy of the overlap of the individual exposures exceeds the development threshold as shown in FIG. The toner adheres here. Thereby, black stripes are generated obliquely.

  However, when the insertion / deletion pixel group is arranged as shown in FIG. 10 of the present invention, the composite energy of the individual exposures is not continuous but intermittent as shown in FIG. For this reason, it is difficult to exceed the development threshold value, or even if the development threshold value is exceeded, in the electrophotographic engine, the toner does not adhere stably, so that no continuous streaking occurs.

  Whether or not the toner adheres is determined by the integrated light amount on the photosensitive member. That is, since the beam shape is broad, it reaches a level at which toner adheres depending on the integrated value of light from a plurality of dots. Therefore, if the pixels are not continuous as shown in FIG. 19 but are intermittently set at several pixels as shown in FIG. 11A, continuous stripes are not generated.

  In the case of enlargement by white pixel insertion instead of black pixel insertion, even if white is inserted in the white area, it is not noticeable. Therefore, white stripes are conspicuous when white pixels are inserted in the black area. FIG. 11B is a diagram for explaining this. Since the black region is entirely laser-lit, the combined energy is as shown in FIG. Here, the white pixel insertion is the same as not exposing the portion, and therefore, the toner does not adhere by the amount corresponding to the combined deletion energy corresponding to the deletion of the individual exposure. However, in the case of FIG. 11 (b), white streak is not seen because it does not fall significantly below the development threshold. Even if it is actually an intermediate area instead of a solid black area, there is a problem of toner scattering in the electrophotographic engine. However, since toner is scattered in the white insertion area, even if white insertion occurs intermittently, This is unlikely to occur with current electrophotographic engines.

  Therefore, regardless of whether black pixels are inserted or white pixels are inserted, a small group having an appropriate number of pixels is formed and inserted intermittently, thereby preventing image streaking from being recognized.

  The case of deletion will be described. In the case of deletion, if the image is black or white, even if the pixel is deleted, it does not become a streak, so there is no problem even if it is deleted without forming a small group. However, if the image has an intermediate density, toner is removed intermittently by forming a small group and deleting it, making it difficult to see the streaks.

  As described above, since the present invention performs the insertion / deletion to form the small group described above regardless of the image density, it is easy to perform the insertion / deletion without detecting an image (particularly an image having an intermediate density). Even a simple structure can be sufficiently put into practical use.

  FIG. 12A shows another arrangement of the insertion / deletion pixel group of the present invention. In this embodiment, the combined energy of the small groups is as perpendicular as possible to the arrangement formed between the small groups, and the distance is increased so as not to overlap the exposure areas between the small groups.

  FIG. 12B shows still another arrangement of the insertion / deletion pixel group of the present invention. That is, this is an example in the case of high resolution, and a total of 12 pixels, 6 pixels in the main scanning direction and 2 pixels in the adjacent sub-scanning direction, are made into a small group.

  FIG. 12C shows still another arrangement of the insertion / deletion pixel group of the present invention. That is, in another arrangement example of FIG. 12B, the distance is set such that the combined energy of the small groups is as perpendicular as possible to the arrangement formed between the small groups.

  FIG. 13 is a diagram for explaining pixel group insertion processing according to the present invention. That is, as shown in FIG. 10, a process for inserting a pixel group (3 pixels) and shifting and correcting an image in the sub-scanning direction is described. Since the image correction (insertion) processing executed by the image correction unit 342 is independently performed by a circuit similar to CMYK, only one color will be described below.

  As shown in FIG. 13 (a), a group of pixels is inserted at positions of black marks (insertion / deletion positions) regularly arranged in parallel in the obliquely downward direction, and the image is shifted in the sub-scanning direction as a whole. As described above, the image is shifted in the sub-scanning direction.

  FIG. 14 is a diagram for explaining the insertion processing of the present invention in detail. Hereinafter, in this embodiment, the address coordinate is an address value that gives a specific image bit when image data is designated by a main scanning line address value (R address value) and a sub scanning line address value (F address value). Define as a set of Further, these address coordinates are determined for each pixel (that is, a pixel column) arranged in a line in the main scanning direction and the sub-scanning direction. Then, the image correction unit 342 performs a shift correction process such as inserting a pixel bit on the pixel located at the coordinate address (that is, the pixel position) designated by the R address value and the F address value.

  FIG. 14A shows an original image of 4800 dpi. Pixels a0, a1, a2,. . In the next row, the pixels are b0, b1, b2,. . Lined up. The addresses in the main scanning direction are set to R0, R1, R2,. . And the sub-scanning direction addresses are F0, F1, F2,. . Represented by

  On the other hand, a process for correcting the shift of the image in the sub-scanning direction is performed. If a pixel group is inserted, the entire image is shifted downward in the sub-scanning direction. On the contrary, in the case of reduction, the pixel group is deleted.

  FIG. 14B shows the insertion position of the pixel group in association with an image by *. Since the information regarding this position is regularly arranged, it is not necessary to actually develop it in the memory. By applying main scanning and sub-scanning by the logic circuit, it is possible to check whether or not this position is satisfied.

A scaling process by inserting a pixel group will be described.
For row F0, first, a0, a1, a2 in columns R0, R1, R2 are read. Since this corresponds to the insertion position as shown in FIG. 14B, black is output as dummy data as pixel data. Then, as shown in FIG. 14 (d), “1” is written into the shift holding registers R 0, R 1, and R 2 to make it “+1”. The shift holding register is changed to +1 because the initial value is 0. Next, a3, a4, and a5 of R3, R4, and R5 are read. Since this does not correspond to the insertion position, a3, a4, and a5 are output as they are. In this way, the first line is processed. The row F0 in FIG. 14C shows the processing result.

  Processing moves to the next F1 line. For R0, R1, and R2, the first pixel is originally to read out b1, b1, and b2, but for R0, R1, and R2, the shift holding register is “1”, so that F0 is one higher. Read row data. Therefore, the outputs are a0, a1, and a2.

  When the process moves to R3, since the shift holding register is “0”, the data is read as it is, and the output is b3. The line F1 in FIG. 14C shows the processing result.

  Processing is performed in the same manner, and F14 will be described. Since R0, R1, and R2 are “1” in the shift holding register, the data one level higher is read and the outputs are i0, i1, and i2. Since R3, R4, and R5 correspond to insertion positions, black pixels are output. Then, as shown in FIG. 14E, “1” is set to R3, R4, and R5 of the shift holding register. Since the shift holding registers of R6, R7, and R8 are “0”, j6, j7, and j8 are output as they are. In this way, the value of the holding register is incremented by 1 at the insertion / deletion position, dummy data is output, and the value on several lines is read according to the value of the shift holding register at a position other than the insertion / deletion position.

  By repeating the above processing, the output image gradually shifts in the sub-scanning direction as compared with the original image (a) as shown in FIG. Thereby, shift processing is achieved. Similarly, reduction processing by shift can be achieved by deleting pixels.

  FIG. 15 is a diagram for explaining the deletion of a pixel group according to the present invention in detail. FIG. 15A shows an original image at 4800 dpi, and the pixels are a0, a1, a2,. . . In the next row, the pixels are b0, b1, b2,. . Lined up.

  The addresses in the main scanning direction are set to R0, R1, R2,. . And the sub-scanning direction addresses are F0, F1, F2,. . Represented by On the other hand, by deleting the pixel group, the entire image is shifted upward in the sub-scanning, and the image is reduced.

  FIG. 15B shows the deletion position of the pixel group with an asterisk in association with the image. Similar to the pixel group insertion processing, the information about this position is regularly arranged, so that it is possible to check whether or not the position corresponds to this position by applying main scanning and sub scanning by the logic circuit. .

A scaling process by deleting a pixel group will be described.
Regarding the row F0, first, the columns R0, R1, and R2 will be described. Since this corresponds to the deletion position as shown in FIG. 15B, b0, b1, and b2 in the next column are output as pixel data. Then, as shown in FIG. 15 (d), “−1” is written into the shift holding registers R0, R1, and R2 to be “−1”. Since the initial value of the shift holding register is 0, the register value is -1. Next, a3, a4, and a5 of R3, R4, and R5 are read. Since this does not correspond to the deletion position, a3, a4, and a5 are output as they are. In this way, the first line is processed. The row F0 in FIG. 15C shows the processing result.

  Processing moves to the next F1 line. For R0, R1, and R2, the first pixel is originally to read out b1, b1, and b2, but for R0, R1, and R2, the shift holding register is “−1”, so Read data in F2 row. Therefore, the outputs are c0, c1, and c2.

  When the process moves to R3, since the shift holding register is “0”, the data is read as it is, and the output is b3. The line F1 in FIG. 15C shows the processing result.

  Processing is performed in the same manner, and F14 will be described. Since the shift holding register is “−1” for R0, R1, and R2, the data in the next lower row is read and the output is k0, k1, and k2. Since R3, R4, and R5 correspond to deletion positions as shown in FIG. 15B, data k3, k4, and k5 in the next lower row are output. Then, as shown in FIG. 15E, “−1” is set to R3, R4, and R5 of the shift holding register. Since the shift holding registers of R6, R7, and R8 are “0”, j6, j7, and j8 are output as they are.

  By repeating the above processing, the output image is gradually shifted upward in the sub-scanning direction as compared with the original image (a) as shown in FIG. Thereby, shift processing is achieved.

  16A is an example of an insertion / deletion occurrence pattern corresponding to the embodiment of FIG. 12B, and FIG. 16B is an insertion / deletion occurrence corresponding to the embodiment of FIG. It is an example of a pattern.

  FIG. 17 shows a detailed configuration (insertion / deletion signal generation circuit) of the image correction unit (FIG. 7). Since the insertion signal is regularly generated with respect to the original image as shown in FIG. 13, it can be generated from the R clock and the F clock. 13 and 14, the F address occurs every 14 intervals and the R address every 12 intervals. However, the initial offset is slightly different in the R address direction.

  In the initial value table 3426, the initial value of the c-adic counter 3425, the F address to be inserted / deleted, and the number of continuous pixels in the main scanning direction are set. 13 and 14, F0 and F14 are set as F addresses, and the c-adic counter 3425 is formed of a quaternary counter. An initial value of 3 is set when F0 is set and 2 is set when F14 is set (quaternary). The initial value of the counter 3425 is 3 when F0 and 2 when F14), and 3 is set as the number of pixels.

  Information regarding the initial value and the F address is stored in advance in the initial value table 3426, and the insertion / deletion frequency can be switched based on the switching signal 3421 from the CPU 320.

  Referring to FIG. 17A, the target line determination unit 3424 determines whether or not the F address counter 3423 that counts the F clock 3430 is an F address to be inserted / deleted set in the initial value table 3426. to decide.

  In the example of FIG. 14, F addresses F0 and F14 are the insertion positions of the sub-scanning addresses, and F0 and F14 are set in the initial value table 3426.

  When the target F address is determined, the c-adic counter 3425 is configured to count a signal obtained by dividing the R clock 3422 corresponding to the R address by the frequency dividing circuit 3428. In the case of FIGS. 13 and 14, a quaternary counter is configured and counts from 0 to 3. When the F address to be inserted / deleted is F0, a carry signal is generated when the counter 3425 is 3. Only while the carry signal of the counter in the main scanning direction is output, a signal obtained by ANDing the R clock 3422 of the number of pixels set in the initial value table 3426 is inserted and deleted (adjacent three pixels R0, R1,. R2) can be issued from the insertion / deletion signal generating circuit 3427 and issued as shown in FIG. 14 (b).

  FIG. 17B shows a configuration of an insertion / deletion signal generating circuit for forming a small group, which is shown in the embodiment of FIG. 12B.

  Referring to FIG. 17B, since the F address counter 3423 counts after the F clock 3430 is divided by F, the target line is determined as a target line, for example, every two lines. When the target F address is determined, the c-adic counter 3425 is configured to count a signal obtained by dividing the R clock 3422 corresponding to the R address by the frequency dividing circuit 3428. In the case of FIG. 16A, a 7-base counter is configured, and 0 to 6 are counted. Only when the carry signal is generated at 6 and the carry signal of the counter in the main scanning direction is output, a signal obtained by ANDing the R clock 3422 with the number of pixels (six pixels) set in the initial value table 3426 is obtained. An insertion / deletion signal generation circuit 3427 generates the insertion / deletion signal. Thereby, an insertion / deletion signal of 2 × sub-scanning direction × 6 main scanning direction can be generated. The deletion signal generation circuit is the same circuit as that shown in FIG.

  The present invention supplies a storage medium storing software program codes for realizing the functions of the above-described embodiments to a system or apparatus, and a program in which a computer (CPU or MPU) of the system or apparatus is stored in the storage medium. This is also achieved by reading and executing the code. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment. As a storage medium for supplying the program code, for example, a hard disk, an optical disk, a magneto-optical disk, a nonvolatile memory card, a ROM, or the like can be used. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) operating on the computer based on an instruction of the program code. A case where part or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing is also included. Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. A case where the CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing is included. Further, the program for realizing the functions and the like of the embodiments of the present invention may be provided from a server by communication via a network.

210 Synchronous detection device 310 GAVD
312 LD driver 340 Memory 342 Image correction unit 344 Output data control unit 346 PLL

JP 2009-83472 A Japanese Patent No. 4253843

Claims (5)

Image forming means for exposing in accordance with an image signal and forming an image by an electrophotographic process, and image correction for enlarging or reducing the image by regularly inserting or deleting pixels (hereinafter referred to as insertion / deletion) to the image In an image forming apparatus provided with a means,
The image correcting means includes a setting means for setting insertion / deletion pixel positions in the main scanning direction and the sub-scanning direction, a frequency dividing means for dividing the main scanning clock, and a first count for counting the outputs of the frequency dividing means. Means for determining whether or not the count value of the second count means is the insertion / deletion pixel position in the set sub-scanning direction; As a result of the determination, when the insertion / deletion pixel position is in the set sub-scanning direction, the main scanning corresponding to the insertion / deletion pixel position in the main scanning direction is based on the count result of the first counting means. said image correction means comprises output means for outputting the insertion deletion signal of the clock, the the insertion deleted pixel group by the plurality of insertion deletion pixels are located adjacent Produced, arranged so that the exposure area between the insertion deletion pixel groups do not overlap it, the image forming apparatus according to claim.   The image forming apparatus according to claim 1, wherein a combined energy of exposure of the insertion / deletion pixel group is orthogonal to an arrangement direction of the insertion / deletion pixel group.   The image forming apparatus according to claim 1, wherein the insertion / deletion pixel group is arranged at an insertion / deletion pixel position in a main scanning direction.   The image forming apparatus according to claim 1, wherein the insertion / deletion pixel group is arranged at a plurality of insertion / deletion pixel positions in the main scanning direction adjacent to each other in the sub-scanning direction.   The image forming apparatus according to claim 1, wherein the insertion / deletion pixel group is arranged at a predetermined angle with respect to a main scanning direction.

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