JP2006197538A - Image reading apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To switch a resolution by switching a control signal for controlling generation and A/D conversion of a read image signal, and further to accelerate a reading speed of a low resolution. <P>SOLUTION: An image reading apparatus includes an image sensor 207 comprising a plurality of line sensors, an A/D converter 11 for converting image signals outputted from the line sensors into image data, an MUX 10 for sequentially selecting the image signals of the line sensors and outputting the image signals to the A/D converter 11 and a clock generator 14 for outputting a control signal for controlling operation to the image sensor 207, the A/D converter 11 and the MUX 10, wherein the clock generator 14 is provided for outputting a control signal (Figures 8-11 (non-illustrated)) for outputting image data of a designated resolution from the A/D converter 11 in accordance with the designated resolution (mode data) among a plurality of resolutions (600, 200, 300dpi). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus including a plurality of line sensors that convert a projected light image into image signals and a signal processing device that converts each image signal into digital data, that is, image data. Although there is no color, the color includes three line sensors that generate R (red), G (green), and B (blue) image signals, and a signal processing device that sequentially converts each color image signal into image data in units of pixels. The present invention relates to an image reading apparatus. The image reading apparatus of the present invention can be used in, for example, an image scanner, a copying machine, and a facsimile.

JP 2004-40146 A Japanese Patent Laid-Open No. 2001-223887 Japanese Patent Application Laid-Open No. 2004-56424.

  In Patent Document 1, three offset adjustment circuits DAC for adjusting the offset of each color image signal R, G, B output in parallel by an image sensor CCD including three line sensors, and three programmable for adjusting the level. A gain amplifier PGA, a multiplexer MUX that sequentially selects and outputs the image signals R, G, and B whose levels are adjusted in units of pixels, and an A / D converter ADC that converts the output into digital data, that is, image data in units of pixels, are incorporated. An analog front end AFE, which is an IC, is described.

  In Patent Document 2, the image data of the image data output from the A / D converter is thinned out by adding the image data of the pixels that are thinned out to reduce the resolution to the image data of the extracted pixels and averaging them. An image reading device that improves the degradation of image quality is described.

  In Patent Document 3, an analog switch that outputs three pixels of image signals as one pixel at the same time is added to an image sensor by combining three consecutive photoelectric conversion elements (pixels) on a line sensor as one set, An image reading apparatus that can be used in a high-resolution output mode that outputs pixel image signals as one pixel and a low-resolution output mode that outputs each set (3 pixels) of image signals as one pixel is described. Yes.

  FIG. 5 shows a main part of the image reading apparatus of the present invention. A conventional example will be described with reference to FIG. FIG. 5 is a block diagram of the reading unit. The CCD 207 as an image sensor outputs an analog image signal corresponding to each of R, G, and B colors of the read image. The analog front end (AFE 212) is an IC having a gain and offset adjustment of the CCD 207 output, an A / D conversion function, and the like, and converts an analog image signal into digital data, that is, image data. The AFE 212 outputs the image data to an image processing unit (not shown) in the subsequent stage, and the image processing unit performs various image processing (shading correction, γ correction, etc.).

  FIG. 12A shows an example of the configuration of a conventional AFE 212. For each of R, G, and B outputs, analog processing circuits and A / D conversion circuits (ADC) 11r, 11g, and 11b are separately provided. FIG. 12B is another example of the configuration of the conventional AFE 212. Each output of the analog processing circuit is sequentially transferred by the multiplexer 10 and converted into a digital signal by one A / D conversion circuit 11. Since this circuit has a small circuit scale, it is often used in an inexpensive color image reading apparatus, and is described in Patent Document 1, for example.

  In the configuration of FIG. 12B, a high sampling rate is required for the A / D conversion circuit 11. For example, when 6 MHz R, G, B signals are input to the AFE 212, the sampling rate required for the A / D conversion circuits 11r, 11g, 11b is 6 MSPS (Mega Sample Per Second) in the configuration of FIG. However, in the configuration of FIG. 12B, the sampling rate required for the A / D conversion circuit 11 is 18 MSPS. Although it is conceivable to use a high-speed A / D conversion circuit, the cost of the AFE 212 is increased. For this reason, a case where a low-speed A / D conversion circuit is used and the color reading speed is lowered is often seen. For example, in the configuration of FIG. 12B, when the maximum sampling rate of the A / D conversion circuit 11 is 6 MSPS, in color reading, the driving frequency of the CCD 207 is set to 2 MHz, and R, G, and B analog images, respectively. The signal is converted into a digital signal by the A / D conversion circuit 11. In monochrome reading, the driving frequency of the CCD 207 is set to 6 MHz, and only the green analog image signal is converted into a digital signal by the A / D conversion circuit. That is, there is a problem that the color reading speed becomes slower than the monochrome reading speed.

  By the way, in many image reading apparatuses, the resolution of output image data is not always the same, and can be changed by a user instruction. For example, even if the reading resolution of the image sensor is 600 dpi, it is possible to obtain a low-resolution output image of 300 dpi or 200 dpi.

  However, in the conventional image reading apparatus, conversion from high resolution data to low resolution data for each reading line (main scanning direction) is performed on the image data. That is, it is performed by an image data processing unit (image processor) subsequent to the A / D converter 11 or an external computer (such as a PC) connected to an image reading device (for example, Patent Document 2). That is, the number of output data (number of output pixels) of the A / D converter 11 for each reading line is the same regardless of the designated (requested) resolution. For this reason, there is a problem that the reading speed is not improved even at the time of low resolution reading due to the restriction of the sampling rate of the A / D converter 11. When the image sensor described in Patent Document 3 is used, an image signal with high resolution and 1/3 of the resolution can be obtained. However, it is considered that the image sensor has a special and complicated configuration and is expensive.

  The first object of the present invention is to switch the resolution by switching the control signal that controls the generation of the image signal and the A / D conversion, and the second object is to improve the reading speed of the low resolution. A third object is to improve the reading speed of low resolution in the above.

(1) An image sensor (207) having a plurality of line sensors, an A / D converter (11) for converting an analog image signal output from the line sensors into digital data, that is, image data, and a plurality of line sensors. A multiplexer (10) for sequentially selecting analog image signals and outputting them to the A / D converter, and a control for controlling the operation of the image sensor (207), the A / D converter (11) and the multiplexer (10). In an image reading apparatus having a clock generator (14) for outputting a signal,
Corresponding to a designated resolution (mode data) among a plurality of resolutions (600, 200, 300 dpi), control signals (FIGS. 8 to 11) for the A / D converter (11) to output image data of the resolution are output. An image reading apparatus comprising a clock generator (14: FIG. 6) for outputting.

  In addition, in order to make an understanding easy, the symbol of the corresponding element of an Example, an equivalent element, or an equivalent matter of an Example which is shown in drawing and mentions later is added to the parenthesis for reference. The same applies to the following.

  According to this, the resolution (600, 200, 300 dpi) of the image data output from the A / D converter (11) can be switched by switching the control signal according to the designated resolution (mode data), and the low resolution reading can be performed. Reading time can be shortened.

  (1a) The clock generator (14) includes control signal generating means (20-55) for generating control signals for the A / D converter (11) to output image data having a plurality of resolutions, And a selection means (60) for selectively outputting a control signal for the A / D converter (11) to output image data of the resolution corresponding to the designated resolution (mode data) of the plurality of resolutions. The image reading apparatus according to (1), including:

  (2) When the number of line sensors is 2 or more, the clock generator (14) transfers the transfer clock (3φ1, 3φ2 of period aT that defines the serial pixel separation of the analog image signal output from each line sensor. ) And the analog image signal of each line sensor are sequentially switched and selected at a period T and are supplied to the A / D converter (11) to output image data at a period aT (3T) for each line sensor (see FIG. The image reading apparatus according to (1) or (1a), including means (20-41) for generating a control signal according to 9).

  (3) When the number of line sensors is 2 or more, the clock generator (14) transfers the transfer clocks (φ1, φ2) having a period T that defines the serial pixel separation of the analog image signal output from each line sensor. ) And the analog image signal of each line sensor are sequentially switched and selected at a period T and are supplied to the A / D converter (11) to output image data at a period aT (3T) for each line sensor (see FIG. The image reading apparatus according to any one of (1) to (2), including means (20-45) for generating a control signal according to 10).

  (4) When the number of line sensors is 2 or more, the clock generator (14) has a period aT / 2 (1.5T) that defines the serial pixel separation of the analog image signal output from each line sensor. A transfer clock and an analog image signal of each line sensor are sequentially switched and selected with a period T and are supplied to the A / D converter (11) to output image data with a period aT (3T) for each line sensor ( The image reading apparatus according to any one of (1) to (3), including means (20-55) for generating a control signal of FIG.

  (5) The clock generator (14) transmits a transfer clock (φ1, φ2) having a period T that defines the serial pixel separation of the analog image signal output from the line sensor and the analog image signal (G of one specific line sensor) ) Only to the A / D converter (11), and a means (20-30) for generating a control signal in the high resolution mode (FIG. 8) for outputting the image data with the period T for the specific line sensor. The image reading apparatus according to any one of (1) to (4) above.

(5a) When the number of line sensors is 2 or more, the clock generator (14)
Clock pulse generator (20);
A first counter (21, 22) that counts the clock pulses generated by the clock pulse generator (20) and counts the first set value (12) to return the count data to the initial value and continue counting;
When the clock pulse generated by the clock pulse generator (20) is counted and the second set value (a × 12) which is a times the first set value (12) is counted, the count data is returned to the initial value and the count is continued. Second counter (31, 32) to perform;
The count data of the first counter (21, 22) is decoded, and the transfer clock (φ1, φ2), reset pulse (φRS), clamp pulse (φCP), and A / D conversion timing for driving the image sensor with period T A / D conversion clock (ADCLK) for regulation, reset pulse (3φRS) and clamp pulse (3φCP), sequential selection of image signals of each line sensor Image signal clamp signal (CLP) for A / D conversion and image signal hold A first set of timing circuits (23-30) including gate means and latch means for generating a signal (S / H);
The count data of the second counter (31, 32) is decoded, the transfer clock (3φ1, 3φ2) for driving the image sensor, the image signal for sequential selection A / D conversion of the image signal of each line sensor, with the period aT A second set of timing circuits (33-41) including gate means and latch means for generating a clamp signal (3-1) CLP and an image signal hold signal (3-1) S / H;
The count data of the second counter (31, 32) is decoded, and the image signal clamp signal (3-2) CLP and the image signal hold signal for the sequential selection A / D conversion of the image signal of each line sensor with the period aT (3-2) A third set of timing circuits (42-45) including gate means and latch means for generating S / H;
The count data of the second counter (31, 32) is decoded, and the transfer clock (1, 5φ1, 1.5φ2), reset pulse (1.5φRS) and clamp pulse (1.5φCP) for driving the image sensor with a period of aT / 2 ) And a fourth set of timings including a gate means and a latch means for generating an image signal hold signal (3-3) S / H for sequential selection A / D conversion of the image signals of each line sensor of period aT Circuit (46-54); and
Transfer clock (3φ1, 3φ2) of the period aT, image signal clamp signal (3-1) CLP and image signal hold signal (3-1) S / H, reset pulse (3φRS) of period aT, clamp pulse ( 3φCP) and A / D conversion clock (ADCLK) as control signals for the high resolution mode (FIG. 9)
Transfer clock (φ1, φ2), reset pulse (φRS), clamp pulse (φCP) and A / D conversion clock (ADCLK) of period T, image signal clamp signal (3-2) CLP and image signal hold of period aT Signal (3-2) S / H as a control signal in the low resolution mode (Fig. 10)
Transfer clock (1.5φ1, 1.5φ2), reset pulse (1.5φRS) and clamp pulse (1.5φCP) of period aT / 2, A / D conversion clock (ADCLK) of period T, and image signal clamp signal of period aT ( 3-3) Selection means (60) for selectively outputting the CLP and the image signal hold signal (3-3) S / H as a control signal for the medium resolution mode (FIG. 11) corresponding to the designated resolution (mode data);
The image reading apparatus according to (1), further comprising:

  (5b) The selection means (60) includes the transfer clock (φ1, φ2), reset pulse (φRS), clamp pulse (φCP), A / D conversion clock (ADCLK), image signal clamp signal CLP having a period T The image signal hold signal S / H is selected and output as a control signal for the monochromatic high resolution mode (FIG. 8) in accordance with the designation of the monochromatic high resolution (monochrome mode); the image reading apparatus according to (5a) above .

  (5c) The number of the line sensors is 3 (a = 3), and each line sensor outputs R, G, and B image signals, respectively, according to any one of (1) to (5b) above. Color image reading device.

  (6) The image reading device (210) according to any one of (1) to (5c), a printer (100) that forms an image represented by image data on a sheet, and the image reading device outputs An image forming apparatus comprising: image data processing means (262) for converting image data to be processed into image data suitable for image formation of the printer.

  (7) The image forming apparatus according to (6), further including a communication unit (270) that converts document information provided from an external device (PC) into image data and outputs the image data to the image data processing unit (262). .

(8) The image reading device (210) according to any one of (1) to (5a) above;
A printer (100) for forming an image represented by image data on paper;
Document information storage means (271-276); and
The image data output by the image reading device is read and corrected and output to the document information storage means (271-276), and the image data output by the document information storage means (271-276) is used for image formation of the printer. Image data processing means (262) for converting into suitable image data and outputting to the printer (100);
An image forming apparatus comprising:

  (9) Document information given from an external device (PC) is stored in the document information storage means (271-276), and the document information is read from the document information storage means (271-276) to the external device (PC). The image forming apparatus according to (8), further including communication means (278-287) for outputting.

  FIG. 1 shows a multi-function full color digital copying machine equipped with an embodiment of the present invention. This full-color copying machine is roughly constituted by units of an automatic document feeder (ADF) 230, an operation board 90, a color scanner 210, and a color printer 100. The operation board 90 and the color scanner 210 with the ADF 230 are units that can be separated from the printer 100. The color scanner 210 includes a control board having a power device driver, a sensor input, and a controller, and a CPU 261 (FIG. 4) Directly or indirectly communicate with 4) and read the document image under timing control.

  A controller board 270 (FIG. 4) to which the printer 100 is connected is connected to a LAN (Local Area Network) to which a personal computer PC is connected. A telephone line PN (facsimile communication line) is connected to the facsimile control unit FCU287 (FIG. 4). ) Connected to the exchange PBX. The printed paper of the color printer 100 is discharged to the paper discharge stack 126 (FIG. 2).

  FIG. 2 shows the mechanism of the color printer 100. The color printer 100 of this embodiment is a laser printer. This laser printer 100 includes four toner image forming units a to d for forming images of each color of magenta (M), cyan (C), yellow (Y), and black (black: K). The transfer belts 107 are arranged in this order along the moving direction of the transfer belt 107 (from left to right in the figure). That is, it is a four-drum type full-color image forming apparatus.

  A neutralizing device 105, a cleaning device 104, a charging device 102, and a developing device 103 are arranged on the outer periphery of the photosensitive member 101 that is rotatably supported and rotates in the direction of the arrow. A space for storing optical information emitted from the exposure device 106 is secured between the charging device 102 and the developing device 103. There are four (a, b, c, d) photoconductors 101, but the image forming component configuration provided around each is the same. The color of the color material (toner) handled by the developing device 3 is different. The photoconductors 101 (four) are photoconductors in which an organic semiconductor layer that is a photoconductive material is provided on the surface of an aluminum cylinder having a diameter of about 30 to 100 mm. A part thereof is in contact with the first transfer belt 107. A belt-like photoreceptor can also be employed.

  The first transfer belt 107 is supported and stretched between the rotating rollers 108, 109, and 110 so as to be movable in the direction of the arrow. On the back side (inside the loop), the first transfer unit 111 is attached to the photoreceptor 101. It is deployed in the vicinity. A cleaning device 112 for the first transfer belt is disposed outside the belt loop. Unnecessary toner remaining on the surface after the transfer from the first transfer belt 107 is wiped off.

  The exposure device 106 irradiates the uniformly charged surface of the photoconductor as a latent image with optical information corresponding to full-color image formation by a known laser system. An exposure apparatus comprising an LED array and an image forming means can also be employed. The first transfer belt 107 is a belt based on a resin film or rubber having a base thickness of 50 μm to 600 μm, and has a resistance value that allows toner to be transferred from the photoreceptor 101.

  In FIG. 2, a second transfer belt 113 is provided on the right side of the first transfer belt 107. The second transfer belt 113 is supported and stretched between the rotating rollers 114, 115 and 116 so as to be movable in the direction of the arrow, and the second transfer means 117 is provided on the back side (inside the loop). A cleaning device 118 for the second transfer belt, a charger 119, and the like are disposed outside the belt loop. After the toner is transferred to the paper, the cleaning device 118 wipes off the remaining unnecessary toner.

  The first transfer belt 107 and the second transfer belt 113 are in contact with each other by the second transfer unit 117, the roller 116, and the roller 108 that supports the first transfer belt 107, thereby forming a predetermined transfer nip. The second transfer belt 113 is a belt having a base of a resin film or rubber having a base thickness of 50 μm to 600 μm, and a belt having a resistance value capable of transferring toner from the first transfer belt 107.

  Paper 120 as a recording medium is stored in paper feed cassettes 121 and 122 in the lower part of the figure, and the uppermost paper is conveyed one by one by paper feed rollers 131 or 132 to a registration roller 133 through a plurality of paper guides. Is done. Above the second transfer belt 113, a fixing device 123, a paper discharge guide 124, a paper discharge roller 125, and a paper discharge stack 126 are arranged.

  A storage portion 127 that can store replenishment toner is provided above the first transfer belt 107 and below the paper discharge stack 126. The toner has four colors, magenta, cyan, yellow, and black, and is in the form of a cartridge 128. The corresponding color developing device 103 is appropriately replenished by a powder pump or the like.

  The frame 129, which is a part of the main body, has a structure that can be rotated and opened around the opening / closing support shaft 130. Therefore, the conveyance path of the recording medium is greatly opened to facilitate the processing of the jammed recording medium (paper). ing.

  Here, the operation of each unit during duplex printing will be described. First, image formation is performed by the photosensitive member 101. That is, by the operation of the exposure device 106, light from an LD light source (not shown) passes through an optical component (not shown), and among the photoconductors 101 uniformly charged by the charging device 102, the photoconductor of the image forming unit a. Then, a latent image corresponding to the writing information (information corresponding to the color) is formed. The latent image on the photoconductor 101 is developed by the developing device 103, and a visible image with toner is formed and held on the surface of the photoconductor 101. This toner image is transferred to the surface of the first transfer belt 107 that moves in synchronization with the photosensitive member 101 by the first transfer unit 111. The remaining toner on the surface of the photoconductor 101 is cleaned by the cleaning device 104 and is discharged by the charge removing device 105 to prepare for the next image forming cycle.

  The first transfer belt 107 carries the toner image transferred on the surface and moves in the direction of the arrow. A latent image corresponding to another color is written on the photoconductor 101 of the image forming unit b, and developed with a toner of the corresponding color to become a visible image. This image is overlaid on the visible image of the previous color already on the first transfer belt 107, and finally four colors are overlaid. In some cases, only monochrome black is formed.

  At this time, the second transfer belt 113 is moved in the direction of the arrow in synchronism, and the image formed on the surface of the first transfer belt 107 is transferred onto the surface of the second transfer belt 113 by the action of the second transfer means 117. The The first and second transfer belts 107 and 113 are moved while the images are formed on the respective photosensitive members 101 of the four image forming units a to d in the so-called tandem format, and the image forming is advanced. Can be shortened.

  When the first transfer belt 107 moves to a predetermined position, a toner image to be created on another surface of the paper is formed again by the photoconductor 101 in the process as described above, and paper feeding is started. When the paper feed roller 131 or 132 rotates counterclockwise, the uppermost paper 120 in the paper feed cassette 121 or 122 is pulled out and conveyed to the registration roller 133.

  The toner image on the surface of the first transfer belt 107 is transferred by the second transfer unit 117 to one side of the sheet fed between the first transfer belt 107 and the second transfer belt 113 via the registration roller 133. Further, the recording medium is conveyed upward, and the toner image on the surface of the second transfer belt 113 is transferred to the other surface of the sheet by the charger 119. At the time of transfer, the sheet is conveyed at a timing so that the position of the image is normal.

  In this embodiment, the polarity of the toner imaged on the photoreceptor 101 is negative. By applying a positive charge to the first transfer unit 111, the toner imaged on the photoreceptor 101 is transferred to the first transfer belt 107. By applying a positive charge to the second transfer unit 117, the toner transferred to the first transfer belt 107 is transferred to the second transfer belt 113. By feeding the paper between the first and second transfer belts 107 and 113 and applying a positive charge to the second transfer means 117, the toner transferred to the first transfer belt 107 is transferred to one side of the paper, The toner transferred to the second transfer belt 113 is given a positive polarity charge from the transfer charger 119, so that the negative polarity toner on the surface of the second transfer belt 113 is sucked and transferred to the other surface of the sheet. The

  The paper on which the toner images are transferred on both sides in the above steps is sent to the fixing device 123, and the toner images (both sides) on the paper are melted and fixed at one time. Are discharged to the paper discharge stack 126.

  As shown in FIG. 2, when the paper discharge units 124 to 126 are configured, a surface (page) to be transferred to the paper later in the double-sided image, that is, a surface directly transferred from the first transfer belt 7 to the paper is the lower surface. Since the image is placed on the discharge stack 126, the second page image is created first and the toner image is held on the second transfer belt 113 in order to align the pages. The image is directly transferred from the first transfer belt 107 to the sheet.

  The image directly transferred from the first transfer belt 107 to the paper is a normal image on the surface of the photoconductor, and the toner image transferred from the second transfer belt 113 to the paper is a reverse image (mirror image) on the surface of the photoconductor. It is exposed as follows. Such image forming order for page alignment and image processing for switching between normal and reverse images (mirror images) are also performed by image data read / write control to the memory MEM by IMAC.

  After the transfer from the second transfer belt 113 to the paper, a cleaning device 118 including a brush roller, a collection roller, a blade, and the like removes unnecessary toner and paper dust remaining on the second transfer belt 113.

  In FIG. 2, the brush roller of the cleaning device 118 is away from the surface of the second transfer belt 113. The structure can swing around the fulcrum 118a and can contact and separate from the surface of the second transfer belt 113. Before the transfer onto the paper, the second transfer belt 113 is released when carrying the toner image, and when the cleaning is necessary, the second transfer belt 113 is swung in the counterclockwise direction in FIG. The removed unnecessary toner is collected in the toner storage unit 134.

  The image forming process in the duplex printing mode in which the “duplex transfer mode” is set has been described above. In the case of duplex printing, printing is always performed by this image forming process. In the case of single-sided printing, there are two types of “single-sided transfer mode by the second transfer belt 113” and “single-sided transfer mode by the first transfer belt 107”, and the single-sided transfer mode using the former second transfer belt 113 is set. In this case, a visible image formed by superimposing four colors (or single color black) on the first transfer belt 107 is transferred to the second transfer belt 113 and transferred to one side of the sheet. There is no image transfer on the other side of the paper. In this case, there is a print screen on the upper surface of the printed paper discharged to the paper discharge stack 126.

  When the single-side transfer mode using the latter first transfer belt 107 is set, a visible image formed on the first transfer belt 107 in a four-color overlap (or single color black) is transferred to the second transfer belt 113. Without being transferred to one side of the paper. There is no image transfer on the other side of the paper. In this case, there is a print screen on the lower surface of the printed paper discharged to the paper discharge stack 126.

  FIG. 3 shows a document image reading mechanism of the scanner 210 and the ADF 230 attached thereto. The document placed on the contact glass 231 of the scanner 210 is illuminated by the illumination lamp 232, and the reflected light (image light) of the document is reflected by the first mirror 233 in parallel with the sub-scanning direction y. The illumination lamp 232 and the first mirror 233 are mounted on a first carriage (not shown) that is driven at a constant speed in the sub-scanning direction y. Second and third mirrors 234 and 235 are mounted on a second carriage (not shown) that is driven in the same direction as the first carriage, and the image light reflected by the first mirror 233. Is reflected downward (z) by the second mirror 234, reflected by the third mirror 235 in the sub-scanning direction y, converged by the lens 236, irradiated to the CCD 207, and converted into an electrical signal.

  The first and second carriages are driven forward (original scanning) and backward (return) in the y direction using the traveling body motor 238 as a drive source. As described above, the scanner 210 is a flatbed type original scanner that scans the original on the contact glass 231 with the lamp 232 and the mirror 233 and projects the original image on the CCD 207. A glass 240 serving as a sheet-through reading window is located at a reading visual field position of the first mirror 233 when one carriage is stopped at a home position (standby position) HP, and an automatic document feeder (ADF) is disposed above the glass 240. ) 13 is mounted, and the transport drum (platen) 244 of the ADF 230 faces the glass 240.

  The documents stacked on the document tray 241 of the ADF 230 are fed between the conveyance drum 244 and the pressing roller 245 by the pickup roller 242 and the registration roller pair 243, and are in close contact with the conveyance drum 244 and pass over the reading glass 240. Then, the paper is discharged onto a paper discharge tray 248 serving as a pressure plate below the document tray 241 by the paper discharge rollers 246 and 247.

  When the image on the surface of the document passes through the reading glass 240 serving as a document reading window, the image is irradiated by the illumination lamp 232 that is moving immediately below the image, and the reflected light on the surface of the document is optical below the first mirror 233. The CCD 207 is irradiated through the system and subjected to photoelectric conversion. That is, it is converted into RGB color image signals. The surface of the transport drum 244 is a white back plate facing the reading glass 240 and is white so as to be a white reference plane.

  Between the reading glass 240 and the scale 251 for positioning the starting edge of the document, there are a reference white plate 239 and a base point sensor 249 for detecting the first carriage. Although the reference white plate 239 reads a document having a uniform density due to variations in individual emission intensities of the illumination lamps 232, variations in the main scanning direction, sensitivity variations among the pixels of the CCD 207, and the like, It is prepared to correct the phenomenon in which read data varies (shading correction).

  The base body 248 of the ADF 230 is hinge-coupled (hinge-connected) to the base body of the scanner 210 on the back side (back side of FIG. 3 paper), and has a handle 250m on the front side of the base body 248 (front side of FIG. 3 paper surface). By raising the base 248, the ADF 230 can be raised (opened). On the back side of the base body 248 of the ADF 230, there is a switch that detects opening and closing of the ADF 230. A pressure plate 250p of the ADF 230 facing the contact glass 231 is mounted on the bottom surface of the ADF 230. When the ADF 230 is closed, the lower surface of the pressure plate 250p is in close contact with the upper surface of the contact glass 231 as shown in FIG.

  FIG. 4 shows the configuration of the image processing system of the multifunction copying machine MF1 shown in FIG. The multi-function copier MF1 includes an engine 260 that performs document image reading and color printing, a controller board 270, and an operation board 90. The engine 260 includes a CPU 261 that controls image reading and printing processes, the color scanner 210 described above, the printer 100 described above, and an image input / output processing 262 configured by an ASIC (Application Specific IC).

  The sensor board unit SBU of the scanner 210 has a CPU, a ROM, and a RAM. The CPU writes the program stored in the ROM into the RAM and executes it, thereby controlling the entire scanner 210. Further, it is connected to a CPU 261 for process control via a communication line, and performs an operation instructed by transmission / reception of commands and data. The CPU in the scanner 210 detects the document detection sensor, HP sensor, pressure plate open / close sensor, cooling fan, etc. and controls ON / OFF. In the scanner 210, a scanner motor driver is driven by a PWM output from the CPU to generate an excitation pulse sequence and drive a pulse motor for scanning a document.

  The original image is illuminated by the light output of the halogen lamp 232 energized by the lamp regulator, and the reflected light of the original, that is, the optical signal, passes through a plurality of mirrors and lenses and passes through three line sensors for reading R, G and B. The image is formed on the CCD 207 including the image. The 3-line CCD 207 receives each drive clock from the AFE 212 on the sensor board unit SBU and outputs an analog image signal of each RGB pixel to the AFE 212.

  The controller board 270 includes a CPU 272, a document storage control 273 configured by an ASIC, a hard disk device (hereinafter referred to as HDD) 122, a local memory (MEM-C) 276, and a system memory (MEM-P) 279. North Bridge (hereinafter referred to as NB) 278, South Bridge (hereinafter referred to as SB) 285, NIC 280 (Network Interface Card), USB device 281, IEEE 1394 device 282, Centronics device 283 and others. The operation board 90 is connected to the document accumulation control 273 of the controller board 270. A facsimile control unit (FCU) 287 is also connected to the document accumulation control 273 by a PCI bus.

  The CPU 272 can transmit and receive document information with a personal computer PC connected to the LAN via the NIC 280 or another personal computer PC via the Internet. In addition, communication with a personal computer, a printer, a digital camera, or the like can be performed using the USB 281, IEEE 1394 282, and Centronics 283.

  The SB 285, the NIC 280, the USB device 281, the IEEE 1394 device 282, the Centronics device 283, and the MLB 284 are connected to the NB 278 via a PCI bus. As described above, the MLB 284 is a board that is connected to the engine 260 via the PCI bus. Then, MLB 284 converts the document data input from the outside into image data (image data), and outputs the converted image data to engine 260.

  The local memory 276, the HDD 122, and the like are connected to the document storage control 273 of the controller board 270, and the CPU 272 and the document storage control 273 are connected through the NB 278 of the CPU chipset. The document accumulation control 273 and the NB 278 are connected via an AGP (Accelerated Graphics Port).

  The CPU 272 performs overall control of the multifunction function copying machine MF1. The NB 278 is a bridge for connecting the CPU 272, system memory 279, SB 285, and document storage control 273. The system memory 279 is a memory used as a drawing memory or the like for the multifunction function copying machine MF1. The SB 285 is a bridge for connecting the NB 278 to the PCI bus and peripheral devices. The local memory 276 is a memory used as a copy image buffer and a code buffer. The HDD 122 is a memory for storing image data, document data, programs, font data, forms, LUT (Look Up Table), and the like. The operation board 90 is an operation unit that receives an input operation from the user and performs display for the user.

  FIG. 4 shows the flow of image data exchanged between the scanner 210 and printer 100 and the image input / output device 262. The image input / output processing 262 performs shading correction, reading gamma correction, MTF correction, etc. on each of the R, G, B image data generated when the color original scanner 210 reads the original image, and corrects it as necessary. There is scanner image processing 263 for converting the later R, G, B image data into C, M, Y, K recording color data, and also R, G, B image data or C, M, Y, K recording color data. Printer image processing 264 for converting the image data into C, M, Y, K print data suitable for the image expression characteristics of the C, M, Y, K color writing units 210 to 213 of the printer 100, and further, a document storage control 273. Image processing I / F (Inte) which outputs the original read image data RGB or CMYK to the printer image processing 264 and outputs the image data RGB or CMYK output by the document storage control 273 to the printer image processing 264. rface circuit) 265.

  In the case of a single copy for printing one sheet per original, the CMYK recording color data is output from the scanner image processing 263 to the image processing I / F 265, and the image processing I / F 265 outputs these image data to the printer image processing 264. The printer image processing 264 performs scaling, image processing, and printer γ conversion and gradation processing as necessary, and outputs to each writing unit (each laser emitter of the laser writing unit 30).

  In the case of continuous copying in which a plurality of sheets are printed per original, the CMYK recording color data is output from the scanner image processing 263 to the image processing I / F 265, and these image data are transferred to the document storage control 273 by the image processing I / F 265. The data is output, temporarily stored in the local memory 272 or the HDD 271, read out for each copy, and supplied from the document storage control 273 to the printer image processing 264 via the image processing I / F 265. The printer image processing 264 performs scaling and image processing as necessary, performs printer γ conversion and gradation processing, and outputs the result to each writing unit.

  When reading and registering a document by the scanner 210 or transmitting to the outside, RGB image data output by the scanner image processing 263 is registered in the HDD 271 via the image processing I / F 265 and the image accumulation control 273, or The data is temporarily stored in the local memory 276 or the HDD 271 and then transmitted to the outside.

  When printing the registered RGB image data by the printer 100 or the RGB image data received from the outside, the RGB image data is given to the printer image processing 264 via the image accumulation control 273 and the image processing I / F 265. The printer image processing 264 converts the RGB image data into CMYK recording color data, and then performs scaling, image processing, printer γ conversion and gradation processing as necessary, and outputs the result to each writing unit.

  FIG. 5 shows an outline of the configuration of the AFE 212 shown in FIG. The AFE 212 is a correlated double sampling circuit (CDS) 1 to 3 that samples and holds R, G, and B image signals for A / D conversion, and an offset adjustment circuit that calibrates the fluctuation range of the image signal within a predetermined range. 4 to 6, programmable gain amplifiers (PGA) 7 to 9 that amplify image signals with specified gain, in color reading mode, R, G, B image signals are selected and output in order, monochrome (single color) reading mode Then, a multiplexer (MUX) that selects and outputs only a G (specific color) image signal, an A / D converter 11 that converts the image signal that is selected and output into image data, an external interface 12, an AFE control 13, and a clock. A generation 14 is provided.

  The image reading apparatus according to the present embodiment has a monochrome mode (600 dpi output), a color high resolution mode (600 dpi output for each color), and a color low resolution mode (200 dpi output for each color) as drive modes for the CCD 207 and the AFE 212. ) And medium color resolution mode (300 dpi output for each color), and the drive mode is selected in accordance with a mode (monochrome / color and resolution combination) designated from the operation board 90 or the PC or copying conditions.

  Here, the main control signals output from the clock generation 14 of the AFE 212 to each part in the CCD 207 and the AFE 212 in each of the monochrome mode, the color high resolution mode, the color low resolution mode, and the medium color resolution mode will be described.

  FIG. 8A shows a control signal that the clock generator 14 gives to the CCD 207 and an image signal that the CCD 207 outputs in the monochrome mode. φ1 and φ2 are transfer clocks, φRS is a reset pulse, φCP is a clamp pulse, and R, G, and B are red, green, and blue outputs of the CCD 207, respectively. The CCD 207 is driven by clocks φ1 and φ2 having a period T (= frequency 1 / T), and serially outputs a photoelectric conversion signal of each pixel on one line, that is, an image signal. One cycle T of the clocks φ1 and φ2 is an image signal output period of one pixel (pixel). That is, the CCD 207 outputs an image signal of each pixel on one line in synchronization with the clocks φ1 and φ2.

  FIG. 8B shows input image signals R, G, B and output image data D of the AFE 212 and control signals in the AFE 212 in the monochrome mode. ADCLK is an A / D conversion clock for designating the A / D conversion timing of the A / D conversion circuit 11, CLP is a clamp signal for CDS1 to 3, S / H is a sample hold signal for CDS1 to 3, and R, G, and B are The output of the CCD 207 (image signal: analog signal) and D is the digital output of the AFE 212 (image data: digital data). In monochrome reading, R and B analog image signals are unnecessary, so only the G analog signal is A / D converted. For this reason, the MUX 10 always selects and outputs the G input. The sampling rate of the A / D converter 11 is 1 / T.

  FIG. 9A shows input / output signals of the CCD 207 in the color high resolution mode. The signal names are the same as in FIG. The CCD 207 is driven by a clock with a period of 3T. That is, the drive clock frequency of the CCD 207 is 1/3 of the monochrome mode. FIG. 9B shows input / output signals of the AFE 212 in the color high resolution mode. The signal name is the same as in FIG. (3-1) CLP (G), (3-1) S / H (G) is in CDS2, (3-1) CLP (B), (3-1) S / H (B) is in CDS3, (3-1) CLP (R) and (3-1) S / H (R) are respectively applied to CDS1. The same applies to other color modes described later.

  Based on the rise of S / H, the MUX 10 sequentially selects and outputs the image signal RGB every T time. This also applies to other color modes described later.

  In high-resolution color reading, it is necessary to A / D convert R, G, B3 image signals. For this reason, the sampling rate of the A / D converter 11 is the same as that in the monochrome mode reading, but the sampling rate per color is 1/3 of the monochrome mode. That is, the reading time for one line is three times that of the monochrome mode.

  FIG. 10A shows input / output signals of the CCD 207 in the color low resolution mode. The signal names are the same as in FIG. The CCD 207 is driven by a clock having a period T. That is, the frequency of the CCD 207 drive clock is the same as in the monochrome mode. FIG. 10B shows input / output signals of the AFE 212 in the color low resolution mode. The signal name is the same as in FIG. In color low-resolution mode reading, it is necessary to A / D convert R, G, B3 analog signals. However, since the resolution of the output image is low, it is not necessary to A / D convert all pixel outputs. For this reason, A / D conversion is performed for every three pixels, and A / D conversion is not performed for the remaining pixels. The sampling rate per color is 1/3 of the monochrome mode as in the color high-resolution mode, but the number of pixels subjected to A / D conversion per reading line is 1/3. Accordingly, the reading time for one line is 1/3 of the color high-resolution mode, that is, the same as the monochrome mode.

  FIG. 11A shows input / output signals of the CCD 207 in the color medium resolution mode. The signal names are the same as in FIG. The CCD 207 is driven with a clock having a period of 1.5T. That is, the frequency of the CCD 207 drive clock is 2/3 of the monochrome mode. FIG. 11B shows input / output signals of the AFE 212 in the color medium resolution mode. The signal name is the same as in FIG. Even in the medium color resolution mode, it is not necessary to A / D convert all pixel outputs. For this reason, A / D conversion is performed for every two pixels, and A / D conversion is not performed for the remaining pixels. The sampling rate per color is 1/3 of monochrome as in the color high resolution mode, but the number of pixels subjected to A / D conversion per reading line is 1/2. Accordingly, the reading time for one line is 1/2 of the color high resolution mode, that is, 1.5 times that of the monochrome mode. The above is summarized as follows.

A. Monochrome mode Resolution: High resolution (600 dpi)
CCD207 drive cycle: T
ADC 11 Conversion Target: G Signal ADC 11 Conversion Period: T
1 line reading time: nT.

B. Color high resolution mode Resolution: High resolution (600 dpi)
CCD207 drive cycle: 3T
ADC 11 conversion target: R, G, B signals (R, G, B pixel unit sequential conversion)
Conversion cycle of ADC 11: T
1 line reading time: 3 × nT.

C. Color low resolution mode Resolution: Low resolution (200 dpi)
CCD207 drive cycle: T
ADC 11 conversion target: R, G, B signals (R, G, B pixel unit sequential conversion)
Conversion cycle of ADC 11: T (for each color, 1/3 decimation conversion)
1 line reading time: nT.

D. Color medium resolution mode Resolution: Medium resolution (300 dpi)
CCD207 drive cycle: 1.5T
ADC 11 conversion target: R, G, B signals (R, G, B pixel unit sequential conversion)
Conversion cycle of the ADC 11: T (1/2 color thinning conversion is performed for each color)
One line reading time: 1.5 × nT.

  FIG. 6 shows a circuit for generating the above-described various control signals of the clock generation 14, and FIG. 7 shows main ones among the various control signals. The first counter 21 and the second counter 31 count up the clock pulses generated by the clock pulse generator (OSC) 20 in FIG. When the count data of the first counter 21 represents the decimal number 12, the output of the AND gate 22 becomes the clear instruction level L, whereby the first counter 21 is cleared and the count data represents 0. As a result, the output of the AND gate 22 is inverted to the high level H, and the counter 21 continues to count up the clock pulses. This operation is repeated. That is, the counter 21 is a circulation counter that repeatedly counts decimal numbers 0 to 11. The second counter 31 is also a cyclic counter, but when the count data reaches 36, the output of the AND gate 32 is inverted to L and clears the counter 31, so the counter 31 repeatedly counts decimal numbers 0 to 35. It is a circulation counter.

  When the count data (first count data) of the first counter 21 becomes 0, the output of the AND gate 23 becomes L, and this is given to the input ports A and C of the data selector 60 as the reset pulse φRS of the period T. When φRS falls from H to L, the flip-flop 24 is set and its Q output becomes H. When the first count data represents 6, the output of the AND gate 25 is inverted to H, whereby the flip-flop 24 is reset and its Q output is inverted to L. The Q output (H) of the flip-flop 24 and the Q bar (Q with overline) output (H) thereof are given to the input ports A and C of the data selector 60 as transfer clocks φ1 and φ2, respectively. It is done. While the first count data represents 3, the output of the AND gate 26 becomes the low level L, and this is applied to the input ports A and C of the data selector 60 as the clamp pulse φCP.

  The flip-flop 27 is set by the clamp pulse φCP and its Q output becomes H. When the first count data represents 9, the output of the AND gate 28 is inverted to H, whereby the flip-flop 27 is reset and its Q output is inverted to L. The Q output (of H) of the flip-flop 24 is given to the input ports A to D of the data selector 60 as the A / D conversion clock ADCLK. When the first count data represents 10, the output of the AND gate 29 is inverted to H, whereby the flip-flop 30 is set and its Q output is inverted to H. When the first count data represents 4, the flip-flop 30 is reset and its Q output is inverted to L. The Q output (of H) of the flip-flop 30 and the Q bar output (of H) thereof are given to only the input port A of the data selector 60 as the clamp signal CLP and the sample hold signal S / H, respectively.

  Both the clamp signal CLP and the sample hold signal S / H are given to CDS2, CLP (G), S / H (G), those given to CDS3, CLP (B), S / H (B), and CDS1. The data is branched into three lines CLP (R) and S / H (R) and supplied to the input port A of the data selector 60. In FIG. 6, the clamp signal CLP and the sample hold signal S / H (four signals in total) to be supplied to CDS3 and CDS1 are indicated by one thick line arrow, and “CLP for B and R, S / H” ".

  The signal given to the input port A of the data selector 60 described above is used in the monochrome mode described above, and mode data representing the monochrome mode is given to the input end of the output selection control of the data selector 60. Are supplied to the CCD 207 and CDS 1 to 3 from the output port of the data selector 60. These input control signals of the input port A that are output from the data selector 60 when the monochrome mode is designated are shown in FIG.

  When the count data (second count data) of the second counter 31 indicates 0, the output of the AND gate 33 becomes H, the flip-flop 34 is set, the Q output is inverted to H, and the Q bar output is inverted to L. To do. When the second count data indicates 18, the output of the AND gate 35 becomes H, the flip-flop 34 is reset, the Q output returns to L, and the Q bar output returns to H. The Q output and Q bar output of the flip-flop 34 are given only to the input port B of the data selector 60 as the transfer clocks 3φ1 and 3φ2 having a period 3T. When the second count data is 0, the output of the AND gate 33 becomes L, and this is given only to the input port B of the data selector 60 as the reset pulse 3φRS having a period 3T. When the second counter is 3, the output of the AND gate 50 becomes L, and this is given only to the input port B of the data selector 60 as a clamp pulse 3φCP with a period 3T.

  When the second count data represents 10, the output of the AND gate 36 is inverted to H, whereby the flip-flop 37 is set and its Q output is inverted to H. When the second count data represents 22, the flip-flop 37 is reset and its Q output is inverted to L. The Q output of the flip-flop 37 is given only to the input port B of the data selector 60 as the clamp signal (3-1) CLP. When the second count data represents 28, the output of the AND gate 39 is inverted to H, whereby the flip-flop 40 is set and its Q output is inverted to H. When the second count data represents 4, the flip-flop 40 is reset and its Q output is inverted to L. The Q output of the flip-flop 40 is given only to the input port B of the data selector 60 as the sample hold signal (3-1) S / H.

  Both of the clamp signal (3-1) CLP and the sample hold signal (3-1) S / H are given to CDS2, CLP (G), S / H (G), those given to CDS3 CLP (B), What is given to S / H (B) and CDS1 is branched into three lines CLP (R) and S / H (R) and given to input port B of data selector 60. In FIG. 6, the clamp signal CLP and the sample hold signal S / H (four signals in total) to be supplied to CDS3 and CDS1 are indicated by one thick line arrow, and “CLP for B and R, S / H” ".

  The signal given to the input port B of the data selector 60 described above is used in the above-described color high resolution mode, and the mode data representing the color high resolution mode is input to the output selection control of the data selector 60. When given to the end, it is given from the output port of the data selector 60 to the CCD 207 and CDS 1 to 3. These input control signals of the input port B output from the data selector 60 when the color high resolution mode is designated are as shown in FIG.

  When the second count data represents 16, the output of the AND gate 42 is inverted to H, whereby the flip-flop 43 is set and its Q output is inverted to H. When the second count data represents 28, the flip-flop 43 is reset and its Q output is inverted to L. The Q output of the flip-flop 43 is given only to the input port C of the data selector 60 as a clamp signal (3-2) CLP. When the second count data represents 22, flip-flop 44 is set and its Q output is inverted to H. When the second count data represents 34, the flip-flop 44 is reset and its Q output is inverted to L. The Q output of the flip-flop 44 is given only to the input port C of the data selector 60 as the sample hold signal (3-2) S / H.

  Both of the clamp signal (3-2) CLP and the sample hold signal (3-2) S / H are given to CDS2, CLP (G), S / H (G), those given to CDS3 CLP (B), What is given to S / H (B) and CDS1 is branched into three lines CLP (R) and S / H (R) and given to input port C of data selector 60. In FIG. 6, the clamp signal CLP and the sample hold signal S / H (four signals in total) to be supplied to CDS3 and CDS1 are indicated by one thick line arrow, and “CLP for B and R, S / H” ".

  The signal given to the input port C of the data selector 60 described above is used in the color low resolution mode described above, and the mode data representing the color low resolution mode is input to the output selection control of the data selector 60. When given to the end, it is given from the output port of the data selector 60 to the CCD 207 and CDS 1 to 3. These input control signals of the input port C output from the data selector 60 when the color low resolution mode is designated are as shown in FIG.

  When the second count data represents 0, the flip-flop 47 is set and its Q output is inverted to H and the Q bar output is inverted to L. When the second count data indicates 9, the output of the AND gate 48 becomes H, the flip-flop 47 is reset, the Q output returns to L, and the Q bar output returns to H. The Q output and Q bar output of the flip-flop 47 are given only to the input port D of the data selector 60 as transfer clocks 1.5φ1 and 1.5φ2 having a period of 1.5T. When the second count data is 0 or 18, the output of the OR gate 49 becomes L, and this is given only to the input port D of the data selector 60 as a reset pulse 1.5φRS having a period of 1.5T. Further, when the second count data is 3 or 21, the output of the OR gate 52 becomes L, and this is given only to the input port D of the data selector 60 as a clamp pulse 1.5φCP with a period of 1.5T. The clamp signal (3-3) CLP given to the input port D is the same signal as the sample hold signal (3-1) S / H given to the input port B. When the second count data indicates 1, the flip-flop 54 is set, and when the second count data indicates 13, the flip-flop 54 is reset. The Q output of the flip-flop 54 is given only to the input port D of the data selector 60 as the sample hold signal (3-3) S / H.

  Both of the clamp signal (3-3) CLP and the sample hold signal (3-3) S / H are given to CDS2, CLP (G), S / H (G), those given to CDS3, CLP (B), What is given to S / H (B) and CDS1 is branched into three lines CLP (R) and S / H (R) and given to input port C of data selector 60. In FIG. 6, the clamp signal CLP and the sample hold signal S / H (four signals in total) to be supplied to CDS3 and CDS1 are indicated by one thick line arrow, and “CLP for B and R, S / H” ".

  The signal given to the input port D of the data selector 60 described above is used in the above-described medium color resolution mode, and the mode data representing the medium color resolution mode is input to the output selector control of the data selector 60. When given to the end, it is given from the output port of the data selector 60 to the CCD 207 and CDS 1 to 3. These input control signals of the input port D output from the data selector 60 when the medium color resolution mode is designated are shown in FIG.

  The image reading apparatus according to the first embodiment uses an image sensor including a 3-line sensor (a = 3), but the present invention uses an image reading apparatus (a = 2) using an image sensor including a 2-line sensor. The same applies to the above. This reading device (a = 2) uses, for example, an image sensor including an odd-numbered pixel reading line sensor and an even-numbered pixel reading line sensor, and a timing circuit for high-resolution reading is controlled by the above-described port B. The configuration is the same as that of the timing circuit for supplying a signal. However, the counter 31 is a circulation counter of 0 to 23, and 3φ1, 3φ1 and the like are 2φ1, 2φ1 and the like of a cycle 2T. The low-resolution reading is configured in the same manner as the timing circuit that gives a control signal to the port A described above, and only the image signal of one line sensor is output from the MUX 10 to the A / D converter 11. Similarly, the present invention is also applied to an image sensor having a total of six (a = 6) line sensors, in which R, G, and B are read as two-line sensors for reading odd-numbered pixels and even-numbered pixels, respectively. It can be applied, and only two lines sensors for odd-numbered pixel reading and even-numbered pixel reading are used for high-definition only G reading, and B and R are each one line sensor for a total of four (a = 4) line sensors. The present invention can also be applied to an image sensor including the above. When B or R is a two-line sensor for reading odd-numbered pixels and even-numbered pixels, the image sensor is provided with a total of five (a = 5) line sensors. The present invention can be applied.

1 is a front view showing the appearance of a full-color copying machine equipped with an embodiment of the present invention and having a composite image processing function. FIG. FIG. 2 is an enlarged vertical sectional view of the color printer 100 shown in FIG. 1. FIG. 2 is an enlarged longitudinal sectional view of a color scanner 210 and an ADF 230 shown in FIG. FIG. 2 is a block diagram illustrating a configuration of an image processing system in the copying machine illustrated in FIG. 1. FIG. 5 is a block diagram illustrating a configuration of a reading unit 211 of the scanner 210 illustrated in FIG. 4 and a configuration of an image reading processing system of a sensor board unit SBU. FIG. 6 is a block diagram showing a partial outline of a functional configuration of a clock generator 14 shown in FIG. 5. FIG. 7 is a time chart showing a change in a control signal generated by each part of the timing circuit shown in FIG. 6. FIG. 5A is a time chart showing input / output signals of the CCD 207 shown in FIG. 5 when reading an image in the monochrome mode. FIG. 5B is an internal control signal and input / output signals of the AFE 212 shown in FIG. 5 when reading an image in the monochrome mode. It is a time chart which shows. 5A is a time chart showing input / output signals of the CCD 207 shown in FIG. 5 when reading a color high-resolution image, and FIG. 5B is an internal control signal and input signals of the AFE 212 shown in FIG. 5 when reading a color high-resolution image. It is a time chart which shows an output signal. 5A is a time chart showing input / output signals of the CCD 207 shown in FIG. 5 when reading a color low-resolution image. FIG. 5B is an internal control signal and input signals of the AFE 212 shown in FIG. 5 when reading a color low-resolution image. It is a time chart which shows an output signal. 5A is a time chart showing input / output signals of the CCD 207 shown in FIG. 5 when reading an image with medium color resolution. FIG. 5B is an internal control signal of the AFE 212 shown in FIG. It is a time chart which shows an output signal. (A) is a block diagram showing an outline of the configuration of a conventional analog front end (AFE) that digitally converts RGB image signals read by a CCD into image data by RGB separate A / D converter ADCs, (b) ) Is a block diagram showing an outline of the configuration of a conventional analog front end (AFE) that sequentially converts RGB image signals read by a CCD into image data in units of pixels by a single A / D converter ADC. .

Explanation of symbols

1-3: Correlated double sampling circuits 7-9: Programmable gain amplifier 10: Multiplexer 11: A / D converter 101: Photoconductor 102: Charging device 103: Developing device 104: Cleaning device 105: Static eliminating device 106: Exposure device 107: first transfer belt 108 to 110: roller 111: first transfer means 112: cleaning device 113: second transfer belt 114 to 16: rotating roller 117: second transfer means 118: cleaning device 119: charger 120: paper ( recoding media)
121, 122: Paper feeding cassette 123: Fixing device 124: Paper ejection guide 125: Paper ejection roller 126: Paper ejection stack 127: Replenishment toner storage 128: Cartridge 129: Frame 130: Opening and closing spindles 131, 132: Paper feeding roller 133: Registration rollers 221, 225: Rotary encoder 224: Stepping motor 231: Document table glass 232: Illumination lamp 233: First mirror 234: Second mirror 235: Third mirror 236: Lens 207: CCD 238: Stepping motor 239: Reference white plate 240: Glass 241: Document tray 242: Pickup roller 243: Registration roller pair 244: Conveying drum 245: Pressing roller 246, 247: Paper discharge roller 248: Pressure plate also serving as a paper discharge tray 249: Base sensor 250: Shaft 251: Suke Le 260: motor control unit

Claims (6)

An image sensor including a plurality of line sensors, an A / D converter that converts an analog image signal output from the line sensor into digital data, that is, image data, and an analog image signal of the plurality of line sensors are sequentially selected and An image reading apparatus comprising: a multiplexer that outputs to an A / D converter; and a clock generator that outputs a control signal for controlling operation to the image sensor, the A / D converter, and the multiplexer.
An image reading apparatus comprising: a clock generator that outputs a control signal for outputting the image data of the resolution corresponding to a specified resolution among a plurality of resolutions by the A / D converter.   When the number of line sensors is 2 or more, the clock generator cycles the transfer clock of the period aT that defines the serial pixel separation of the analog image signal output from each line sensor and the analog image signal of each line sensor. 2. The image reading apparatus according to claim 1, further comprising means for generating a high-resolution mode control signal for sequentially switching and selecting at T and supplying to the A / D converter and outputting image data at a period aT for each line sensor. .   When the number of line sensors is 2 or more, the clock generator cycles the transfer clock of period T that defines the serial pixel separation of the analog image signal output from each line sensor and the analog image signal of each line sensor. 3. A unit according to claim 1, further comprising means for generating a low-resolution mode control signal for sequentially switching and selecting at T and supplying to the A / D converter and outputting image data at a period aT for each line sensor. The image reading apparatus described in one.   When the number of line sensors is 2 or more, the clock generator generates a transfer clock having a period aT / 2 that defines the serial pixel separation of the analog image signal output from each line sensor and the analog image signal of each line sensor. 4. A means for generating a control signal in a medium resolution mode for sequentially switching and selecting the signal at a period T and supplying the selected data to the A / D converter to output image data at a period aT for each line sensor. The image reading apparatus according to claim 1.   The clock generator supplies the A / D converter with only a transfer clock having a period T that defines the serial pixel separation of the analog image signal output from the line sensor and the analog image signal of one specific line sensor. 5. The image reading apparatus according to claim 1, further comprising means for generating a control signal in a high-resolution mode for outputting image data at a period T for each of the line sensors. The image reading apparatus according to claim 1, a printer that forms an image represented by image data on a sheet, and an image that is suitable for image formation of the printer using image data output from the image reading apparatus. An image forming apparatus comprising image data processing means for converting data.

Images