JP2009085995A - Printer controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To print an image of high quality without lowering performance, when correcting tilt or skew of an optical system by correcting a bitmap image. <P>SOLUTION: The pixel is offset by pixel or at a fixed point in accordance with an output image. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a tandem color image forming apparatus including a plurality of color developing units and a unit for sequentially transferring a plurality of color images formed by the developing units.

  In recent years, in order to increase the image forming speed in an electrophotographic color image forming apparatus, the same number of developing devices and photosensitive drums as the number of color materials are provided, and images of different colors are sequentially placed on an image conveying belt or a recording medium. The number of tandem color image forming apparatuses that transfer images is increasing. In this tandem color image forming apparatus, it is already known that there are a plurality of factors that cause registration deviation, and various countermeasures have been proposed for each factor. One factor is the non-uniformity of the lens of the deflection scanning device, the mounting position shift, and the mounting position shift of the deflection scanning device to the color image forming apparatus body. In that case, the scan line is inclined or bent, and the degree of the change differs for each color, resulting in registration shift.

  As a method for coping with this registration deviation, Patent Document 1 discloses that a scanning line bend is measured by using an optical sensor in an assembly process of a deflection scanning apparatus, and a lens is mechanically rotated to bend the scanning line. A method of fixing with an adhesive after adjusting is described.

  In Patent Document 2, in the process of assembling the deflection scanning apparatus into the color image forming apparatus main body, the inclination of the scanning line is measured using an optical sensor, and the deflection scanning apparatus is mechanically tilted to thereby tilt the scanning line. A method of adjusting and assembling the color image forming apparatus main body is described.

  Patent Document 3 describes a method of measuring the inclination of a scanning line and the amount of bending using an optical sensor, correcting bitmap image data so as to cancel them, and forming the corrected image. ing.

  Since this method electrically corrects the image data by processing it, it eliminates the need for a mechanical adjustment member or an adjustment process during assembly, compared to the methods described in Patent Document 1 and Patent Document 2. It is possible to deal with registration errors at low cost.

  As shown in FIG. 4, this electrical registration deviation correction is performed when a certain amount of deviation occurs in the sub-scanning direction with respect to the beam deviation amount (before correction), as in the image after the transfer process in FIG. Is generated (for each transfer point), and the inclination and the curve of the scanning line are offset.

Some products, such as the image after the interpolation process of FIG. 5, perform the interpolation process and make the transfer point inconspicuous, and can output a good print result.
JP 2002-116394 A JP 2003-241131 A JP 2004-170755 A

  However, the conventional example has the following inadequate points.

  That is, in order to electrically correct the bitmap image printed on the printer, it is necessary to form a bitmap image according to the inclination or bending of the optical system of the engine.

  At this time, it is necessary to form an image in which the image in the sub-scanning direction is changed from the bitmap image once developed on the memory with reference to the transfer point calculated from the characteristics according to the tilt and the curve of the optical system.

  When a large number of transfer points are generated or when a change point is generated at a complicated position, it takes a long time to create an optically corrected bitmap, resulting in a problem that the performance of the printer is remarkably lowered.

  In the present embodiment, a bit map based on the means for storing the inclination and the curvature of the optical system of each color, the calculation means for calculating the registration shift amount from the inclination and the curvature of the optical system of each color, and the calculation means In a printer control apparatus having means for calculating an image transfer point, the transfer point of the bitmap image is a fixed point.

  Further, the transfer point calculation means can also calculate transfer points for each pixel.

  In that case, according to the print mode (high image quality, dither pattern) of the image to be output, switching between a fixed transfer point and a transfer point for each pixel can be selected.

  As described above, when correcting or correcting the tilt or bend of the optical system by correcting the bitmap image, the transfer point calculated at that time is printed as a fixed unit without degrading performance. I can do it.

  In addition, even when it is desired to perform high-quality printing, it is possible to output a high-quality image according to the print mode by switching between a fixed unit of transfer points and a unit of one pixel.

  Next, details of the present invention will be described in accordance with the description of the embodiments.

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

  FIG. 2 is a diagram showing a printing system to which the printer of the present invention is applied.

  In the drawing, reference numeral 2 denotes a printer which inputs data from various external devices such as a host computer and executes recording on a recording medium.

  In this embodiment, the printer 2 is a laser beam printer. The configuration of the laser beam printer to which this embodiment is applied will be described below with reference to FIG.

  In FIG. 2, reference numeral 2 denotes a printer body which inputs and stores printing information (character code, etc.), form pattern information, compressed image data, etc. supplied from a host computer connected to the outside. I can do it.

  In addition, it has a function of forming an image on a recording sheet as a storage medium while creating a corresponding character pattern, form pattern, or the like according to the information, or developing compressed image data.

  Reference numeral 200 denotes an operation panel on which switches and LED indicators for various operations are arranged, and 201 denotes a printer control unit that executes overall control in the printer 2 and analyzes character information supplied from a host computer or the like. (Controller).

  The printer control unit 201 mainly converts character information into a video signal having a corresponding character pattern or transfers the compressed image data to the laser scanner unit 209 while expanding the compressed image data.

  When printing is started, the printer 2 starts a paper feeding operation for feeding recording paper into the apparatus from the paper feeding cassette 202 or the manual feed tray 203.

  The recording paper thus fed is sent to the paper feed unit 204 and conveyed so as to sequentially pass through the developing units 205, 206, 207 and 208.

  At the same time, the image data for each color developed by the controller 201 is sent to the laser scanner unit 209 after image conversion processing.

  The laser scanner unit 209 is a circuit for driving a semiconductor laser, and switches ON / OFF of laser light emitted from the semiconductor laser in accordance with input image data.

  For the image data sent to the laser scanner unit 209, the photosensitive drums of the phenomenon units 205, 206, 207, and 208 are laser-scanned based on the image data for each color, and a desired color is formed on the photosensitive drum corresponding to each color. An image is formed.

  By synchronizing the formation of the image data for each color with the conveyance of the recording paper, the color image of each color is developed on the recording paper conveyed by the conveyance unit 204.

  Further, sensors for detecting the remaining amount of toner are attached to the developing units 205, 206, 207, and 208, and information from the sensors is sent to the control system of the recording unit in accordance with the decrease in toner.

  The recording paper on which the color image is printed in this manner is thermally fixed by the fixing unit 210 and is abolished in the paper feed tray 211.

  With such a configuration of the printer 2, since development can be performed independently for each color, a printed image can be obtained at a very high speed.

  FIG. 3 is a block diagram showing a detailed configuration of the printer control unit 201 in the printer 2 described above. In FIG. 3, reference numeral 315 denotes an interface unit (I / F unit), which is code data or compressed by an external device. Input image data.

  Reference numeral 302 denotes a CPU that executes a control program stored in the ROM unit 304 and controls the entire printer.

  Reference numeral 303 denotes a RAM unit 1 that provides an area for storing recording data sent from the host computer for printing and a work area necessary for the CPU 302 to execute various controls as a work memory.

  A ROM unit 304 stores various programs (firmware) to be executed by the CPU 302.

  Reference numeral 301 denotes an ASIC that includes a HOST I / F control unit 315, a CPU I / F control unit 316, a memory control unit 305, decompression circuits 306, 307, 308, and 309, and a transfer processing unit 102, 103, 104, and 105.

  The HOST I / F control unit 315 exchanges control signals with the host computer and transmits data through an interface cable.

  As for data reception, in conjunction with the memory control unit 305, the received data is stored in the RAM unit 1303 by DMA control.

  The CPU I / F control unit 316 literally controls the interface with the CPU 302, and controls access to control registers and data registers (not shown) in the ASIC.

  The memory control unit 305 is a block that controls access to the ROM unit 304 and the RAM unit 1 303 and controls DMA transfer and arbitration between blocks.

  The decompression circuits 306, 307, 308, and 309 output the compressed image data stored in the RAM unit 1 from the RAM unit 1 according to the arbitration of the memory control unit 305 according to the request signal output from each decompression circuit. Means for receiving compressed image data.

  In the decompression circuit, there are decompression circuits for yellow (Y), magenta (M), cyan (C), and black (K), respectively, and decompress the compressed image data transferred from the RAM unit 1303 and transfer it. The data is output via the processing units 102, 103, 104, and 105.

  In addition, the CPU 302 always exchanges commands and status with the recording unit at regular intervals, grasps the state of the recording unit, sends a print command, etc., and exchanges with the recording unit.

  Next, the operation of this embodiment will be described with reference to the flowchart of FIG.

  First, when the host computer starts printing, an image is formed on the host computer, the formed image is compressed, and the compressed image is input to the printer via various interfaces.

  On the printer side, various parameters necessary for printing are input and set from S801.

  In step S <b> 802, the information is sent from the storage element storing the optical system tilt and bending information stored on the engine side to the host side via the controller board.

  On the host side, the transfer point is calculated based on the sent tilt and turn information.

  In S803, the output mode of the image to be output is determined.

  In normal printing, an output mode that uses fixed unit transfer points is set in order to increase the printer's printing speed. When printing with high image quality, the printer's printing speed is reduced to 1/2 or 1/3. Is used.

  Here, when normal printing is selected, a fixed transfer point is calculated from S804 based on the tilt and bend information.

  As shown in FIG. 7, the fixed transfer point indicates that transfer between lines does not occur unless the transfer point at a fixed position is reached as compared with an ideal correction curve.

  If high-quality printing is selected, a transfer point is calculated in units of one pixel from S805 based on the tilt and curve information.

  As shown in FIG. 6, the calculation of the transfer point in units of one pixel indicates that a transfer point is generated when the ideal correction curve crosses the threshold as compared with the ideal correction curve.

  When the transfer point is calculated, information on the transfer point is transmitted from the host side to the controller side from S806.

  Upon receiving the transfer point information, the controller side sets the transfer point information of each color in the transfer processing units 102, 103, 104, and 105 of FIG. 3 from S807.

  FIG. 1 is a block diagram of a transfer processing unit, and each color transfer processing unit has the same configuration.

  Further, the memory control unit 107 controls the memory unit 2 101 while sharing the timing with the transfer processing unit for each color.

  When various settings of the printer are completed, compressed image data is sent from the host side from S808.

The compressed image data is once stored in the RAM unit 1303 and waits for the start of printing.
When printing is started from S809, the image data stored in the RAM unit 1303 is read out and transferred to the transfer processing unit while being decompressed by the decompression circuits 306, 307, 308, and 309.

  The image data transferred to the transfer processing unit is once stored in the RAM unit 2101.

  Here, based on the transfer point information set in the transfer register 109, the address generation unit 108 generates a read address for reading an image.

  The memory control unit 107 reads image data from the RAM unit 2 101 in accordance with the address generated by the address generation unit 108.

  The read image data is output from the SEL unit 111 to the engine unit. When the fixed transfer point is set, the image data read from the RAM unit 2101 is output to the engine unit as it is. .

  When the transfer point is set in units of one pixel, the image processing unit 110 performs image matching.

  In the image alignment, since the line change occurs within the word length read by the RAM unit 2101, the pixels are rearranged according to the transfer point.

  Access to the RAM unit 2101 frequently occurs due to image matching. However, the engine speed may be changed to 1/2 or 1/3 according to the number of transfer points or the position.

  When the image data is output to the engine, it is determined whether or not image data for one page has been sent from S810, and the process ends when the data for one page has been sent.

  In the above embodiment, the controller side creates an image corresponding to the transfer point as shown in the flowchart of FIG. 8, but the host side creates an image corresponding to the transfer point as shown in the flowchart of FIG. A configuration of transferring to the controller side may be adopted.

  In the flowchart of FIG. 9, when the transfer point is calculated in S904 or S905, an image corresponding to the transfer point is created in S906.

  In this case, since the host creates an image according to the transfer point, an image creation time according to the host performance is required.

  In image creation, in the normal print mode, it is possible to print without reducing the engine speed by creating an image at the transfer point corresponding to the transfer point calculated at the fixed point.

  Even in the high-quality print mode, since the image corresponding to the transfer point calculated in units of one pixel by the host is created, the transfer processing unit on the controller side can be simplified and the cost of the apparatus can be reduced. I can do it.

Block diagram of this embodiment Block diagram of the printer Block diagram of printer control device Color shift diagram in the sub-scanning direction Illustration of interpolation processing Transfer diagram of one pixel unit Fixed unit transfer diagram Flow chart of this embodiment Flowchart of another embodiment

Explanation of symbols

101 RAM section 2
102 Transfer control unit Y
103 Transfer controller M
104 Transfer control part C
105 Transfer control part K
DESCRIPTION OF SYMBOLS 106 Engine part 107 Memory control part 108 Address generation part 109 Transfer register 110 Image processing part 111 SEL part 301 ASIC part 302 CPU
303 RAM part 1
304 ROM section 305 Memory control section 306 Decompression circuit Y
307 Expansion circuit M
308 Decompression circuit C
309 Expansion circuit K
315 HOST I / F section 316 CPU I / F section 317 HOST

Claims (4)

  Means for storing the inclination and curvature of the optical system for each color, calculation means for calculating the amount of registration deviation from the inclination and curvature of the optical system for each color, and calculating the transfer point of the bitmap image based on the calculation means And a means for performing image transfer control according to the transfer point and generating a transferred image, wherein the transfer point of the bitmap image is a fixed point. Printer controller.   2. The printer control apparatus according to claim 1, further comprising means for selecting the fixed transfer point and the transfer point calculated in units of one pixel in accordance with an output image quality mode and speed.   3. The printer control apparatus according to claim 1, wherein the fixed transfer point is a word length multiplied by a CPU or memory used in the apparatus.   4. The printer control apparatus according to claim 1, further comprising means on the host computer side that performs image transfer control according to the transfer point and generates a transferred image. .

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