JP2006076087A - Image processor and method of processing image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processor capable of using an image memory according to a printing mode without waste. <P>SOLUTION: This image processor comprises ROSs 7C, 7M, 7Y and 7K having a plurality of writing modes for changing the number of lines of images concurrently formed on photosensitive drums 6C, 6M, 6Y and 6K, a memory read IF 15 for reading pixel data recorded in an image memory 14 and correction data for registration correction according to each of the writing modes to output them to the ROSs 7C, 7M, 7Y and 7K, and a memory write IF 12 for changing the number of pieces of pixel data and the number of pieces of correction data to be written in the image memory 14 according to each of the plurality of memory modes. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image processing apparatus including a writing unit capable of simultaneously writing a plurality of lines.

  In recent years, VCSEL (Vertical Cavity Surface Emitting Laser) has been developed to meet the demand for higher speed and higher resolution for printers and to be able to produce devices with multiple light emitting points at low cost. A technique to be used has been proposed (see Patent Document 1).

  FIG. 1 shows a configuration of an image writing unit 100 having a surface emitting laser. The light beam output from each light emitting point of the surface emitting laser 101 is incident on the rotary polygon mirror 104 via the collimator lens 102 and the cylinder lens 103, respectively.

  Each light beam incident on the rotary polygon mirror 104 is deflected in the main scanning direction by the rotation of the rotary polygon mirror 104. At this time, each light beam is incident in a shifted direction in the sub-scanning direction. Each light beam reflected by the reflecting surface of the rotary polygon mirror 104 is irradiated onto the photosensitive drum 107 via the toroidal lens 105 and the scanning lens 106. That is, since a plurality of lines can be scanned simultaneously, an image can be written on the photosensitive drum 107 at a high speed.

JP-A-5-294005

  As described above, an image writing unit using a surface emitting laser can simultaneously write a plurality of lines, so the number of output lines can be made variable according to the image quality and printing speed of the image to be printed, that is, the writing mode. Is assumed. For example, a part of the plurality of lines once written is overwritten again at the next writing. A high-quality image can be formed by this double exposure mode. When it is desired to increase the printing speed, the image writing unit performs writing by the number of lines that can be simultaneously written.

  As described above, in the image writing using the surface emitting laser, a plurality of writing modes are possible. Therefore, it is necessary to use the image memory more efficiently in accordance with the writing mode. For example, in a tandem-type image forming apparatus, registration correction (hereinafter referred to as registration correction) for correcting a positional shift of each color is performed. The amount of correction data increases in accordance with the accuracy of registration correction.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an image processing apparatus and an image processing method that can use an image memory without waste in accordance with a print mode.

  In order to achieve such an object, an image processing apparatus according to the present invention includes an image forming unit having a plurality of writing modes capable of changing the number of lines of an image simultaneously formed on an image carrier, and recording according to the writing mode. Read out pixel data recorded in the means and registration correction correction data, output to the image forming means, and according to the plurality of write modes, the number of pixel data to be written in the recording means and the number of pixel data Writing means for changing the number of correction data is provided.

  When the number of pixel data necessary for image formation is changed according to the mode, the number of pixel data that needs to be written in the recording unit is also changed. Therefore, when the number of pixel data to be written in the recording means is small, registration correction can be performed with high accuracy by writing a large amount of registration correction data. Further, when the number of pixel data read from the recording unit increases, the number of pixel data to be written to the recording unit is increased and the correction data is decreased. Thereby, an image can be formed at high speed.

  In the image processing apparatus, the reading unit changes the increment number of a line counter that counts the number of lines according to the writing mode, and reads out a predetermined number of lines of pixel data when reading out pixel data of a predetermined number of lines. A new line may be added to the line by the increment number to obtain the predetermined line number.

  New lines are added in increments to several lines of the previously read lines, and pixel data of a predetermined number of lines is output. Therefore, the number of pixel data read from the recording unit can be changed according to the increment number. Accordingly, the image quality and the image forming speed can be adjusted according to the image to be formed.

  In the image processing apparatus, the image forming unit is a unit that simultaneously forms an image for a plurality of lines on the image carrier, and an image of a line to be written this time is applied to a predetermined number of lines written previously. A double exposure mode in which images are formed in an overlapping manner and an adjacent exposure mode in which images for the plurality of lines are formed in the sub-scanning direction for each writing may be provided.

  Since the double exposure mode and the adjacent exposure mode are provided, the image quality and the image formation speed can be adjusted according to the image to be formed.

  In the image processing apparatus, the writing unit may record the pixel data and the correction data of a plurality of colors in one recording unit.

  Since pixel data and correction data of a plurality of colors are written in one recording means, the number of recording means can be reduced and the cost of the apparatus can be reduced.

  In the image processing apparatus, the reading unit may be set so that the number of new lines to be added is larger in the monochrome mode than in the color mode for forming a color image.

  In the monochrome mode, there is no problem such as color misregistration, so that the image quality can be maintained even if printing is performed at high speed.

  The image processing method of the present invention reads out pixel data recorded in a recording means and correction data subjected to registration correction, and forms an image on an image carrier according to the pixel data and the correction data; And changing the number of pixel data and the number of correction data to be written to the recording means according to a plurality of writing modes provided in the image writing means.

  When the number of pixel data necessary for image formation is changed according to the mode, the number of pixel data that needs to be written in the recording unit is also changed. Therefore, when the number of pixel data to be written in the recording means is small, registration correction can be performed with high accuracy by writing a large amount of registration correction data. Further, when the number of pixel data read from the recording unit increases, the number of pixel data to be written to the recording unit is increased and the correction data is decreased. Thereby, an image can be formed at high speed.

  The present invention can utilize the image memory without waste in accordance with the print mode.

  Preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  First, the configuration of the present embodiment will be described with reference to FIG. In FIG. 2, a document 2 placed on a document table 1 is R (red) and G (green) by an image scanner including a color CCD sensor 3 via a scanning optical system including a light source and a scanning mirror. , B (blue) analog image signals. The analog image signals of R, G, and B read by the color CCD sensor 3 are converted into Y (yellow), M (magenta), C (cyan), and K (black) color images by the image processing unit 4. Image data of each color is sequentially output to ROS (Raster Output Scanner) 7C, 7M, 7Y, 7K of the forming units 5C, 5M, 5Y, 5K. Laser beams emitted from these ROSs 7C, 7M, 7Y, and 7K in accordance with image data are scanned and exposed on the surfaces of the respective photosensitive drums 6C, 6M, 6Y, and 6K to form electrostatic latent images. The electrostatic latent images formed on the photosensitive drums 6C, 6M, 6Y, and 6K are developed as toner images of respective colors Y, M, C, and K by the developing devices 8C, 8M, 8Y, and 8K, respectively. In this embodiment, as the ROS 7C, 7M, 7Y, and 7K, a writing unit that includes a surface emitting laser as shown in FIG. 1 and that can simultaneously write a plurality of lines is used.

  Further, the misregistration amount measuring unit 9 shown in FIG. 2 obtains the misregistration amounts of the C, M, Y, and K color images forming the image. There are various methods for measuring the amount of misalignment by the misalignment measuring unit 9. For example, as shown in FIG. 3, a registration deviation measurement pattern P is formed over the entire circumference of the transfer belt 70, and the registration deviation measurement pattern P is repeatedly sampled by the positional deviation amount measurement unit 9 at a predetermined timing. From the sampling data obtained in this way, for example, the registration deviation amount of each color (yellow, magenta, cyan) with reference to black is detected, and these are divided by the number of samplings to calculate the average registration deviation amount R. Registration correction is performed based on the deviation amount R. The displacement amount measured by the displacement amount measuring unit 9 is sent to the control unit 10.

  Next, the configuration of the image processing unit 4 will be described with reference to FIG. As shown in FIG. 4, the image processing unit 4 includes a control unit 10, a main scanning registration correction unit 11, a memory write interface (hereinafter also referred to as a memory write IF) 12, a memory read / write selection unit 13, an image memory 14, A memory read interface (hereinafter also referred to as a memory write IF) 15, a sub-scanning registration correction unit 16, and a data output unit 17 are provided. The main scanning registration correction unit 11, the memory write IF 12, the memory read / write selection unit 13, the image memory 14, the memory read IF 15, the sub-scanning registration correction unit 16, and the data output unit 17 are an ASIC (Application Specific Integrated Circuit). Configured as part.

  The control unit 10 controls each unit of the image processing unit 4. Also, a registration correction correction amount is determined from the positional shift amount measured by the positional shift amount measuring unit 9 and notified to the main scanning registration correcting unit 11 and the sub-scanning registration correcting unit 16. The control unit 10 generates main scanning registration correction instruction information from the amount of positional deviation in the main scanning direction, and outputs the main scanning registration correction instruction information to the main scanning registration correction unit 11. Further, sub-scanning registration correction instruction information is generated from the amount of positional deviation in the sub-scanning direction, and is output to the sub-scanning registration correction unit 16.

  The control unit 10 receives an instruction of a print mode set by the user by operating an operation unit (not shown). The print mode is a setting that prioritizes image quality or a setting that prioritizes printing speed by reducing image quality. The control unit 10 sets the write mode of ROS 7C, 7M, 7Y, 7K according to the set print mode. In this embodiment, there are two types of write modes. In the first mode, for example, when the number of lines that can be written simultaneously by ROS 7C, 7M, 7Y, and 7K is N (N is a natural number of 2 or more), N lines are written without being overwritten as shown in FIG. It is a mode to go. This mode is called an adjacent exposure mode. In this adjacent exposure mode, an image is written on the photosensitive drum N lines at a time, so that printing can be performed at high speed. The second mode is a double exposure mode in which a part of the previously written line is overwritten. For example, when N lines are written by ROS 7C, 7M, 7Y, and 7K, the next writing is shifted by N / 2 lines in the sub-scanning direction as shown in FIG. 6 and is superimposed on the previously written image by N / 2. . That is, an image is always written twice for each line. In this double exposure mode, since N / 2 is written at a time, the printing speed is slower than in the adjacent exposure mode, but the image quality can be improved. In FIG. 6, the first written image and the second written image are slightly shifted to show that the images are superimposed, but in actuality, the images are accurately aligned.

  The main scanning registration correction unit 11 inputs an image, performs registration correction in the main scanning direction, and writes the corrected image in the image memory 14 via the memory write IF 12. A main scanning registration correction amount from the control unit 10 is input to the main scanning registration correction unit 11. The control unit 10 outputs a registration correction amount in the main scanning direction based on the positional deviation amount to the main scanning registration correction unit 11. When the image data for one line is input, the main scanning registration correction unit 11 performs pixel insertion and thinning according to the main scanning registration correction amount notified from the control unit 10 to write the corrected image data to the memory write. Write to the image memory 14 via the IF 12. The image memory 14 stores pixel data for a plurality of lines and correction data by registration correction.

  The memory write IF 12 switches the number of data to be written to the image memory 14 at a time according to the write mode instructed from the control unit 10. For example, in the adjacent exposure mode described above, image data is written for each N lines, and in the double exposure mode, image data is written for each N / 2 lines.

  The image memory 14 is provided with a memory read / write selection unit 13 for switching between reading and writing of data. In this embodiment, since the 1-port RAM is used as the image memory 14, it is impossible to simultaneously write and read image data. Accordingly, the memory write IF 12 outputs a data write request to the memory read / write selection unit 13 at the timing of writing image data. Similarly, the memory read IF 15 outputs a data read request to the memory read / write selection unit 13 when the image data read timing comes.

  The image memory 14 shown in FIG. 4 is used as an image memory for two colors. As shown in FIG. 7A, pixel data of two colors is recorded in one image memory 14. That is, the memory write IF 12 that writes an image to the image memory 14, the memory read IF 15 that reads pixel data, the main operation registration correction unit 11, the sub operation registration correction unit 16, and the data output unit 17 are used in common for two colors. For example, as shown in FIG. 7A, the M color and the Y color can be used in common, and the K color and the C color can be used in common. In this case, one ASIC 20 shown in FIG. 4 includes an image memory 14 for M and Y and an image memory 14 for K and C, and a memory write IF 12 for writing image data for each image memory 14; The memory read / write selection unit 13 and the memory read IF 15 are provided.

  Note that the image memory 14 may be provided for each color as shown in FIG. In this case, four chips are mounted on one ASIC 20, and a memory write IF 12, a memory read / write selection unit 13, and a memory read IF 15 are provided for each color.

  The memory read IF 15 changes the image data read from the image memory 14 according to the write mode instructed from the control unit 10. For example, in the adjacent exposure mode described above, image data is written for each N lines, and in the double exposure mode, the number of increments of the line pointer is set to N / 2, and the previously read N / 2 line and the new N / 2 line are read. Read the image.

  A sub-scanning registration correction amount from the control unit 10 is input to the sub-scanning registration correction unit 16. The sub-scanning registration correction unit 16 starts reading image data from the image memory 14 when image data for a plurality of lines is accumulated in the image memory 14. The sub-scanning registration correction unit 16 reads the same line (or part of the line) twice (insertion processing) or reads the line (or part of the line) according to the sub-scanning registration correction amount notified from the control unit 10. By skipping reading and reading out the next line (or part of the line) (thinning-out process), registration correction is performed, and image data after registration correction for one line is output to the outside.

  As described above, since the ROS 7C, 7M, 7Y, and 7K of the present embodiment have the double exposure mode and the adjacent exposure mode, the number of lines of pixel data newly read out from the image memory 14 also depends on this mode. change. The control unit 10 changes the increment number of the line counter according to the write mode of ROS 7C, 7M, 7Y, 7K. For this reason, the number of pixel data required to be written in the image memory 14 for the next data writing is also changed. Therefore, when the number of pixel data to be written in the image memory 14 is small, a large amount of registration correction data is written. This makes it possible to perform registration correction with high accuracy. Further, when the number of pixel data read from the image memory 14 increases, the number of pixel data written to the image memory 14 is increased and the correction data is decreased. Thereby, an image can be formed at high speed.

  The above-described embodiment is a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.

It is a figure which shows the structure of the image writing unit using a surface emitting laser. It is a figure which shows the structure of an image processing apparatus. It is a figure for demonstrating the measuring method of positional offset amount. 2 is a diagram illustrating a configuration of an image processing unit 4. FIG. It is a figure which shows adjacent exposure mode. It is a figure which shows double exposure mode. It is a figure which shows the structure of an image memory.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Original stand 2 Original 3 Color CCD sensor 4 Image processing part 5C, 5M, 5Y, 5K Image forming unit 6C, 6M, 6Y, 6K Photosensitive drum 7C, 7M, 7Y, 7K ROS
8C, 8M, 8Y, 8K Developer 9 Position shift amount measurement unit 10 Control unit 11 Main scanning registration correction unit 12 Memory write IF 13 Memory read / write selection unit 14 Image memory 15 Memory read IF
16 Sub-scanning registration correction unit 17 Data output unit

Claims (6)

An image forming means having a plurality of writing modes capable of changing the number of lines of an image simultaneously formed on the image carrier;
A reading unit that reads out pixel data recorded in the recording unit and registration correction correction data according to the writing mode, and outputs the pixel data to the image forming unit;
An image processing apparatus comprising: writing means for changing the number of pixel data to be written to the recording means and the number of correction data according to the plurality of writing modes.   The reading means changes the increment number of a line counter that counts the number of lines according to the write mode, and reads the predetermined number of pixel data to the predetermined line of the previously read lines when the pixel data is read. The image processing apparatus according to claim 1, wherein new lines are added to obtain the predetermined number of lines.   The image forming means is a means for simultaneously forming an image for a plurality of lines on the image carrier, and forms an image by superimposing an image of a line to be written this time on a predetermined number of previously written lines. 3. The image processing apparatus according to claim 1, further comprising a double exposure mode and an adjacent exposure mode in which an image for the plurality of lines is formed in the sub-scanning direction for each writing.   The image processing apparatus according to claim 1, wherein the writing unit records the pixel data and the correction data of a plurality of colors in one recording unit.   3. The image processing apparatus according to claim 2, wherein the reading unit is set so that the number of new lines to be added is larger in the monochrome mode than in the color mode for forming a color image. Reading out pixel data recorded in the recording means and correction data subjected to registration correction, and forming an image on an image carrier according to the pixel data and the correction data;
An image processing method comprising: changing the number of pixel data written to the recording unit and the number of correction data according to a plurality of writing modes provided in the image writing unit.

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