JP2005269683A - Digital copier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital copier capable of minutely adjusting the size of an input image while changing a variable power ratio little by little for a read image although an original is read only one time. <P>SOLUTION: An image processing unit 33 is provided with a shading corrector 51, a filter processor 52, a first magnification processor 53a, a second magnification processor 53b, a memory I/F 54, a γ converter 55, and an image quality processor 56. The processors 53a and 53b are provided before and after the memory I/F 54, respectively. After the processor 53a performs magnification processing, image data are stored into a memory 35, and the processor 53b also performs magnification processing again for the image data outputted from the memory 35. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a digital copier that converts read document image information into an electrical signal, digitally processes it, and performs optical writing on a photosensitive member with a laser to form an image, and particularly relates to a scaling control technique.

  The digital copying machine irradiates a document placed downward on a contact glass with a light source, forms an image of the reflected light on the image sensor with a lens, photoelectrically converts it, and further converts it into a digital signal with an A / D converter. Various image processing is performed. Further, the laser is modulated by the image information signal after image processing, the image information is optically written on the photosensitive member by the modulated laser to form an electrostatic latent image, and the developed image is developed with toner. As a result, the visible image is transferred onto the sheet fed from the sheet feeding unit, so that an image is finally formed on the sheet.

A digital copying machine generally has a memory function. The image data once read is stored in the memory, and read out from the memory as necessary to perform electronic sorting. What rotates 90 degree | times or 270 degree | times is known. For example, in Japanese Patent Application Laid-Open No. 9-130582, even when an original image is rotated 90 degrees or 270 degrees using the memory function and the document scanning speed is finely adjusted, output is performed. There has been proposed a technique for preventing a difference in magnification between a vertical direction and a horizontal direction in an image.
(For example, refer to Patent Document 1).

JP-A-9-130582

  As described above, some digital copiers have a function of storing read image data once in a frame memory and outputting a plurality of stored images without scanning a document again. At this time, there is a great demand to output a plurality of images with the magnification changed little by little. For example, in the case of a copying machine that handles a large document such as A0, there is a demand to obtain an output of a desired size, although it is desired to read at once to avoid damaging the document.

  The present invention has been made in view of such a background. The original can be read only once, and the size of the output image can be finely adjusted by gradually changing the magnification of the read image. The purpose is to provide a digital copier.

  In order to achieve the above object, according to the first aspect of the present invention, reflected light from a document is read by a line image sensor and converted into an electrical signal, and after A / D conversion, various image processing is performed by an image processing unit. In a digital copying machine that outputs a laser modulation signal and performs optical writing on a photosensitive member by a laser to form an image, a first scaling unit and a second scaling unit are respectively provided at a front stage and a rear stage of a frame memory. And a processing unit, wherein the data subjected to the scaling process by the first scaling unit is stored in the frame memory, and the data read from the frame memory is processed again by the second scaling unit. To do.

  In order to achieve the above object, according to the second aspect of the present invention, reflected light from a document is read by a line image sensor and converted into an electrical signal, and after A / D conversion, various images are processed by an image processing unit. In a digital copier that performs processing to output a laser modulation signal and optically writes to a photoconductor with a laser to form an image, a first scaling unit and a second variable are respectively provided at the front and rear stages of the frame memory. A magnification processing unit, and an image quality processing unit in the previous stage of the frame memory, the scaling process in the first scaling processing unit, and the image quality processed data in the image quality processing unit are stored in the frame memory, The data read from the frame memory is processed again by the second scaling unit.

  In order to achieve the above-mentioned object, the invention according to claim 3 reads the reflected light from the original with a line image sensor, converts it into an electrical signal, and further A / D-converts it. In a digital copier that performs processing, outputs a laser modulation signal, and writes an image on the photosensitive member by a laser to form an image, the image data is subjected to scaling processing in order to perform scaling processing before the frame memory. And a second selection unit for switching the image data output from the frame memory to the scaling unit again.

  In order to achieve the above object, according to a fourth aspect of the present invention, in the first and second aspects of the present invention, the FIFO memory used in the scaling processing unit at the subsequent stage of the frame memory is a scaling process at the preceding stage of the frame memory. It is smaller than the FIFO memory of a part.

  According to the first aspect of the present invention, in the case of a digital copying machine in which data before image quality processing (quantization) is stored in the frame memory, the main scanning electric magnification after the memory storage and the main scanning synchronization signal of the memory unit are stored. By changing the cycle, it is possible to finely adjust the scaling factor for the data stored in the memory. For this reason, when finely adjusting the image size for the image output once stored in the memory, it is not necessary to scan the document again.

  According to the second aspect of the present invention, in the case of a digital copying machine in which the data after image quality processing (quantization) is stored in the frame memory, the main scanning electric magnification after the memory storage and the main scanning synchronization signal of the memory unit are stored. By changing the cycle, it is possible to finely adjust the scaling factor for the data stored in the memory. For this reason, when finely adjusting the image size for the image output once stored in the memory, it is not necessary to scan the document again.

  According to the third aspect of the present invention, the scaling operation performed before the memory accumulation and the scaling operation performed after the memory accumulation can be performed by the common circuit, so that the circuit scale is reduced.

  According to the fourth aspect of the present invention, since the FIFO memory of the scaling circuit for the scaling process performed after memory storage is made smaller than the FIFO memory in the previous stage, the circuit scale is reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram of a digital copying machine.

  First, the image reading unit 1 will be described. A contact glass 2 for placing a document is provided on the upper surface of the apparatus, and a light source 4 is arranged as a traveling body 5 so that the lower part thereof can be moved horizontally (moving in the sub-scanning direction). A mirror 3 that reflects light from the document in the horizontal direction is integrally formed with the light source 4 at a lower portion between the light sources 4. In order to sequentially reflect the light from the mirror 3 every 90 degrees, a traveling body composed of the mirror 6 and the mirror 7 is provided so as to be able to travel according to the movement of the light source 4.

  A mirror 6 is provided for reflecting light from the mirror 3 downward, and a mirror 7 for reflecting light from the mirror 6 in a direction opposite to the light from the mirror 6 is provided at the lower part of the mirror 6. A lens 8 is disposed in the light emission path of the mirror 7, and a line image sensor (CCD) 9 is disposed at the focal point.

  Next, the printer unit 11 will be described. The printer unit 11 includes an image forming system centered on the photosensitive drum 12 and a paper feeding / conveying system. The image forming system includes a photosensitive drum 12, a charger 13 around it, a laser array 14, a developing device 15, a transfer device 16, a separator 17, a cleaning device 18, and a static elimination lamp 19. The sheet feeding / conveying system includes three-stage sheet feeding cassettes 21, 22, 23, a manual feed tray 24, a registration roller 25, a conveying belt 26, a fixing device 27, a branching claw 28, and a double-sided conveying path (reverse conveying path) 29. Yes.

  In such a configuration, a laser modulated in accordance with image information is output from the laser array 14, and writing is performed on the photosensitive drum 12. The electrostatic latent image thus formed becomes a toner image by the developing device 15. On the other hand, the sheet sent from any of the cassettes 21 to 23 or the manual feed tray 24 stands by the registration roller 25 and is sent out toward the transfer unit in synchronization with the front end of the toner image.

  The sheet on which the toner image has been transferred by the transfer unit is sent to the fixing unit 27 by the conveyance belt 26, where fixing is performed. Thereafter, the paper is discharged out of the apparatus or conveyed to the double-sided conveyance path 29. The surface of the photosensitive drum 12 from which the paper has been separated is cleaned by the cleaning device 18 and further neutralized by the neutralizing lamp 19, and then again faces the charging device 13 and is uniformly charged.

  FIG. 2 is a block diagram showing the electrical system of the digital copying machine. The electrical system includes a scanner control unit 31, a video processing unit 32, an image processing unit 33, a system control unit 34, a memory unit 35, a printer control unit 36, and an LED writing head 37.

  The image signal system will be described. The image signal read by the CCD 9 is given an appropriate gain by the video processing unit 32, A / D converted, and output as 8-bit digital data DATA (7: 0) synchronized with ck (1). . A CCDSTN for determining the readout timing of the CCD 9 and ck (1), which is a 20 MHz clock, are sent from the image processing unit 33 to the video processing unit 31.

  FIG. 3 is a block diagram of the image processing unit. The image processing unit 33 includes a shading correction unit 41, a filter processing unit 42, a scaling processing unit 43, a memory I / F 44, a γ conversion unit 45, and an image quality processing unit (quantization unit) 46. In the image processing unit 33, after black offset correction, shading correction, MTF correction, and electrical scaling in the main scanning direction are performed, image quality processing such as γ correction and dithering and error diffusion is performed.

  The function of each block will be described. The black offset correction is correction for subtracting the dark current black level of the CCD 9 from the image data. In the shading correction, in order to remove unevenness of the light amount of the light source in the main scanning direction and sensitivity difference between the pixels of the CCD 9, the white plate having a uniform density is read before starting the document scanning, and the data is stored for each pixel. Correction is performed by dividing the image data being read by the stored white plate data for each pixel.

  The MTF correction is to correct deterioration of optical frequency characteristics and the like with a two-dimensional spatial filter. In the scaling circuit, the scaling process in the main scanning direction is performed using an interpolation calculation by a three-dimensional convolution method. The image quality processing unit 46 performs character processing, error diffusion processing, dither processing, and the like according to the mode after γ conversion.

  The image data SDT (3: 0) that has undergone a series of processing is sent to the printer control unit 36. Then, it is sent to the LED write head 37 after performing speed conversion in accordance with the write clock. The LED write head 37 controls the pulse width of the current and the amount of current applied to the semiconductor laser in accordance with the 4-bit 16 gradation image data. The data after the scaling process passes through the path control unit and is sent to the memory unit 35 where the image data is compressed, decompressed, stored, and transferred to the counter unit.

  A case where image reading is performed in a mode in which a read document is temporarily stored in a memory will be described with reference to FIG. Place the document on the contact glass 2 with the image side down and press the start button. As a result, a scan start signal is output from the CPU to the image processing unit 33, and FGATE indicating the image effective range in the sub-scanning direction becomes ACTIVE. The traveling body 5 starts to move in the left direction in FIG. 1, and sub-scanning is performed on the document. The reflected light (reading light) from the original illuminated by the light source 4 reaches the CCD 9 via the mirror 3 → the mirror 6 → the mirror 7 → the lens 8 in order.

  The CCD 9 converts incident light into an electrical signal. This signal is A / D converted by the video processing unit 32 and sent to the image processing unit 33. The data sent to the image processing unit 33 is subjected to black offset correction, shading correction, MTF correction, and electrical scaling in the main scanning direction, and then stored in the memory unit 35 through the memory I / F 44.

  The stored image data is read from the memory unit 35 together with the gate signal according to an instruction from the system control unit 34. At this time, the main scanning synchronization signal, the main scanning gate signal, and the sub scanning gate signal are generated by the memory unit 35 in accordance with the values given from the system control unit 34.

  The output data from the memory unit 35 is subjected to image quality processing such as γ correction, dithering and error diffusion, and the data is quantized according to the number of bits on the printer side. Subsequently, the image data is sent to the printer control unit 36. The above is the configuration and operation of the digital copying machine as the basis of the present invention.

  Next, the present invention will be specifically described. First, a first embodiment will be described. FIG. 4 is a block diagram of the image processing unit showing the first embodiment. The image processing unit includes a shading correction unit 51, a filter processing unit 52, a first scaling processing unit 53a, a second scaling processing unit 53b, a memory I / F 54, a γ conversion unit 55, and an image quality processing unit 56. . A first scaling processing unit 53a and a second scaling processing unit 53b are provided before and after the memory I / F 54.

  In the first embodiment, after shading correction, 8-bit data subjected to filter processing and first scaling processing is stored in the memory unit 35 through the memory I / F 54.

  The configurations of the shading correction, the filter process, and the first scaling process are the same as the general one shown in FIG. The 8-bit data read from the memory unit 35 is again processed by the second scaling processing unit 53b. The configuration of the second scaling processing unit 53b is the same as that of the first scaling processing unit 53a. As a result, fine adjustment of the magnification in the main scanning direction is performed.

  As shown in FIG. 2, the memory unit 35 generates a main scanning synchronization signal, a main scanning gate signal, and a sub scanning gate signal in accordance with image data output from the memory. The period and effective width of these signals are controlled by the system control unit 34. In this system, image writing is performed by an LED head. For this reason, the line interval is determined by controlling the interval of the main scanning synchronization signal, thereby enabling fine adjustment of the scaling factor in the sub-scanning direction. Increasing the interval between the synchronization signals enlarges the image, and shortening the interval between the synchronization signals reduces the image.

  The purpose of scaling after storing the memory in such a system is to perform fine adjustment of the size of the output image. For this reason, the range of the variable magnification is not required for both main scanning and sub-scanning, but the accuracy is required to be about 0.1%. The 8-bit image data after fine adjustment is γ-converted in the same way as in normal copying, quantized by the image quality processing unit 56 in accordance with the image quality mode, and finally converted to 4 bits that can be handled by the writing device. Is output.

  According to this embodiment, in a digital copying machine having a configuration in which data before image quality processing is stored in a memory, it is possible to finely adjust a scaling factor for the data after storage in the memory.

  FIG. 5 is a block diagram of an image processing unit showing the second embodiment. The image processing unit includes a shading correction unit 51, a filter processing unit 52, a first scaling processing unit 53a, a γ conversion unit 55, an image quality processing unit 56, a second scaling processing unit 53b, a memory I / F 54, a quantum The conversion unit 57 is provided. A first scaling processing unit 53a and a second scaling processing unit 53b are provided before and after the memory I / F 54.

  In the second embodiment, after shading correction, 4-bit data after performing filter processing, first scaling processing, γ conversion processing, and image quality processing is stored in the memory unit 35 through the memory I / F 54. It has become. Since the 4-bit data read from the memory unit 35 passes (m3, m2, m1, m0) through a scaling circuit using an 8-bit width, (m3, m2, m1, m0, m3, m2, m1, m0), and so on. Thereafter, the processing by the second scaling processing unit 53b is performed again. As a result, electric zooming in the main scanning direction is performed.

  As shown in FIG. 2, the memory unit 35 generates a main scanning synchronization signal, a main scanning gate signal, and a sub scanning gate signal in accordance with image data output from the memory. The period and effective width of these signals are controlled by the system control unit 34. In this system, image writing is performed by an LED head. For this reason, the line interval is determined by controlling the interval of the main scanning synchronization signal, thereby enabling fine adjustment of the scaling factor in the sub-scanning direction. Increasing the interval between the synchronization signals enlarges the image, and shortening the interval between the synchronization signals reduces the image.

  The purpose of scaling after storing the memory in such a system is to perform fine adjustment of the size of the output image. For this reason, the range of the variable magnification is not required for both main scanning and sub-scanning, but the accuracy is required to be about 0.1%. Since the image data after fine adjustment becomes 8-bit data by the interpolation calculation of the second scaling processing unit 53b, the upper 4 bits are taken, quantized again to 4 bits, and output.

  According to this embodiment, in a digital copying machine having a configuration in which data after image quality processing is stored in a memory, it is possible to finely adjust a scaling factor for the data after the memory is stored.

  FIG. 6 is a block diagram of an image processing unit showing the third embodiment. In the third embodiment, a single scaling processing unit 53 is used by switching to a memory front side and a memory back side by a selector. Scaling is performed by switching the selector (3) for the 8 bits of data after filtering. The data after the scaling process is returned to the path for performing the γ conversion by the selector (2). The configuration is such that 4-bit data after image quality processing after γ conversion is stored in the memory unit 35 through the memory I / F 54. In this state, all the originals are scanned and taken into the memory unit 35.

  Next, data read from the memory unit 35 is read. At this time, reading by the scanner has already been completed. The 4-bit data read from the memory unit 35 expands (m3, m2, m1, m0) to 8 bits as (m3, m2, m1, m0, m3, m2, m1, m0). . Thereafter, the selector (3) is switched to perform a scaling process on the read data from the memory unit 35. As a result, electric zooming in the main scanning direction is performed.

  As shown in FIG. 2, the memory unit 35 generates a main scanning synchronization signal, a main scanning gate signal, and a sub scanning gate signal in accordance with image data output from the memory. The period and effective width of these signals are controlled by the system control unit 34. In this system, image writing is performed by an LED head. For this reason, the line interval is determined by controlling the interval of the main scanning synchronization signal, thereby enabling fine adjustment of the scaling factor in the sub-scanning direction. Increasing the interval between the synchronization signals enlarges the image, and shortening the interval between the synchronization signals reduces the image.

  The purpose of scaling after storing the memory in such a system is to perform fine adjustment of the size of the output image. For this reason, the range of the variable magnification is not required for both main scanning and sub-scanning, but the accuracy is required to be about 0.1%. The 8-bit image data after fine adjustment is quantized again to 4 bits, and is output to the printer side through the selector (4).

  According to this embodiment, in a digital copying machine having a configuration in which data after image quality processing is stored in a memory, it is possible to finely adjust a scaling factor for the data after the memory is stored. In the specification, when the scaling circuit before reading into the memory and the scaling circuit after reading from the memory are not used at the same time, an increase in hardware can be suppressed by using the scaling circuit in common.

  Next, a fourth embodiment will be described. The block configuration of the fourth embodiment is basically the same as that of the first embodiment shown in FIG.

  In the fourth embodiment, after shading correction, 8-bit data subjected to filter processing and first scaling processing is stored in the memory unit 35 through the memory I / F 54.

  The 8-bit data read from the memory unit 35 is again processed by the second scaling processing unit 53b. The configuration of the second scaling processing unit 53b is the same as that of the first scaling processing unit 53a. As a result, fine adjustment of the magnification in the main scanning direction is performed. Fine adjustment of the magnification in the sub-scanning direction is performed by controlling the interval of the main scanning synchronization signal. The purpose of scaling after storing the memory in such a system is to perform fine adjustment of the size of the output image. For this reason, the range of the variable magnification is not required for both main scanning and sub-scanning, but the accuracy is required to be about 0.1%.

  FIG. 7 is a block diagram of the scaling processing unit in the former stage of the memory, and FIG. 8 is a block diagram of the scaling processing unit in the latter stage of the memory. Each of the first scaling processing unit 53a shown in FIG. 7 and the second scaling processing unit 53b shown in FIG. .

  The length of the FIFO 63 of the first scaling unit 53a, which is a pre-memory scaling block, is prepared in the main scanning direction. In the case of enlargement processing, image data for one line is once stored in the FIFO 63. The accumulated image data is subjected to enable control in accordance with the variable magnification by the speed conversion control unit 62 and is read out at a slow rate. The interpolation calculation unit 61 calculates data to be interpolated in accordance with the read data. Since the algorithm of the interpolation calculation unit 61 is known, the description thereof is omitted.

  In the case of the reduction process, the virtual sampling points that have been reduced by passing the data through the interpolation calculation unit 61 are generated. This data is written into the FIFO 63 under the control of the speed conversion control unit 62. The written data is read from the FIFO 63 at a normal speed. Writing to and reading from the FIFO 63 are performed by using two FIFOs 63 as toggles. This is because the circuit becomes simple and it is necessary to perform an image shift operation.

  Here, let us consider the internal operation assuming that the range of the scaling factor required for the second scaling processing unit 53b is 95% to 105% and there is no shift operation. Since there is no shift operation, the FIFO 63 shown in FIG.

  9A and 9B are diagrams for explaining the operation of the FIFO during enlargement. FIG. 9A shows the operation in a normal length FIFO, and FIG. 9B shows the operation in a FIFO with a limited length. FIG. 10 is a diagram for explaining the operation of the FIFO at the time of reduction. (A) shows the operation in the normal length FIFO, and (b) shows the operation in the FIFO with a limited length. First, a case where the length of the FIFO 63 is normal (5000 pixels in this embodiment) at the time of enlargement will be considered with reference to FIG. Since the reading speed is slower than the writing speed, the read address has advanced only halfway when the writing for one line is completed. When the writing of the next line starts, reading starts again from the beginning. In the case of 105%, the difference from the read address when writing is completed is given by 5% of 5000 pixels, which is 250 pixels.

  Here, the length of the FIFO 63 is limited. This is shown in FIG. 9B. Of course, if the FIFO 63 is shorter than the number of data in one line, the write address returns to the beginning and the data is overwritten. However, it suffices if reading is completed before overwriting. From the above, the maximum difference between the write and read addresses is 250. Therefore, no problem occurs if the length of the FIFO 63 is at least 250.

  Next, FIG. 10A shows a case where the FIFO 63 has a normal length at the time of reduction. Since the writing speed is slower than the reading speed, the reading catches up with the writing if the reading does not start after the writing progresses to some extent. In the case of 95%, data is overwritten unless 250 pixels are separated. Here, the length of the FIFO 63 is limited. This is shown in FIG. 10 (b). The timing of writing and reading is 250 pixels apart and the length is 250 pixels. Thus, the length of the FIFO 63 can be shortened if the range of the scaling factor to be realized is narrow. Therefore, the necessary amount of FIFO 63 can be minimized.

1 is an overall configuration diagram of a digital copying machine. 1 is a block diagram showing an electrical system of a digital copying machine. It is a block diagram of an image processing part. It is a block diagram of the image processing part which shows 1st Embodiment. It is a block diagram of the image processing part which shows 2nd Embodiment. It is a block diagram of the image processing part which shows 3rd Embodiment. FIG. 6 is a block diagram of a scaling processing unit in the previous stage of the memory. FIG. 6 is a block diagram of a scaling processing unit at a later stage of the memory. It is a figure which shows the operation | movement of FIFO at the time of expansion. It is a figure which shows the operation | movement of FIFO at the time of reduction.

Explanation of symbols

31 Scanner Control Unit 32 Video Processing Unit 33 Image Processing Unit 34 System Control Unit 35 Memory Unit 36 Printer Control Unit 37 LED Write Head 51 Shading Correction Unit 52 Filter Processing Unit 53a First Scaling Processing Unit 53b Second Scaling Processing Part 54 Memory I / F
55 γ conversion unit 56 Image quality processing unit

Claims (4)

The reflected light from the original is read by a line image sensor and converted into an electrical signal, and after A / D conversion, various image processing is performed by an image processing unit to output a laser modulation signal. In digital copiers that write and form images,
A first scaling unit and a second scaling unit are provided at the front and rear stages of the frame memory, respectively.
A digital copier characterized by storing data scaled by the first scaling processing section in a frame memory, and processing data read from the frame memory again by the second scaling processing section. The reflected light from the original is read by a line image sensor and converted into an electrical signal, and after A / D conversion, various image processing is performed by an image processing unit to output a laser modulation signal. In digital copiers that write and form images,
A first scaling unit and a second scaling unit at the front and rear stages of the frame memory, respectively, and an image quality processing unit at the front stage of the frame memory,
The data subjected to the scaling process in the first scaling unit and the image quality processed in the image quality processing unit are stored in the frame memory, and the data read from the frame memory is processed again in the second scaling unit. A digital copying machine characterized by The reflected light from the original is read by the line image sensor and converted into an electrical signal, and after A / D conversion, various image processing is performed by the image processing unit to output a laser modulation signal. In digital copiers that write and form images,
First selection means for switching the image data to the scaling processing unit in order to perform scaling processing in the preceding stage of the frame memory;
Second selection means for switching the image data output from the frame memory again to the scaling processing unit;
A digital copying machine characterized by comprising: In claim 1 and claim 2,
A digital copying machine, wherein a FIFO memory used for a magnification processing unit at a rear stage of a frame memory is smaller than a FIFO memory of a magnification processing unit at a front stage of a frame memory.

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