JP2007049298A - Line image sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a line image sensor for establishing compatibility between the improvement of the color reproducibility of an image reading apparatus and reduction in color shift. <P>SOLUTION: The line image sensor, including a photodiode group configured with four kinds or more of photodiode arrays and color filters, with different color separation characteristics and each mounted on each photodiode, is provided with a means that composes electric charges produced by two or more of the photodiodes located at the end of the photodiode group. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image reading apparatus that reads a document image, and more particularly to a line image sensor that achieves both improvement in color reproducibility and prevention of image quality deterioration due to vibration.

  Conventionally, as an image reading apparatus using a line image sensor, a digital copying machine or a facsimile is known.

  FIG. 21 shows a combined configuration of a generally known reduction optical type image reading device 3000 and a document feeder 2000 (hereinafter referred to as DF) that automatically conveys an original, and is particularly a general configuration in a digital copying machine.

  In the configuration shown in the drawing, there are provided two reading methods for reading an image of a document: a flow scanning using DF2000 and a platen reading for scanning a document placed on a document glass 3001 while moving and scanning.

  In platen reading, a document placed on a document glass 3001 is illuminated by a document illumination lamp 3004, a first reflecting shade 3013, and a second reflecting shade 3014, and the reflected light from the document is reflected on a first mirror 3005 and a second reflecting shade. An image is formed on the three-line image sensor 3011 via the mirror 3006, the third mirror 3007, and the optical lens 3010, and the first mirror stage 3008 and the second mirror stage 3009 are moved at a speed of 2: 1 by the optical motor 3012. This is done by scanning in the B direction. At this time, the paper discharge tray 2014 of the DF2000 functions as a pressure plate for pressing the document.

  The read image is calibrated by shading correction using the reference white plate 3002, and the edge light amount deterioration of the optical lens 3010 and the sensitivity unevenness of the three-line image sensor 3011 are corrected and output.

  On the other hand, for the scanning reading, the first mirror table 3008 is arranged and fixed under the flow reading glass 3020, and the document placed on the document tray 2002 is separated with the paper feed roller 2004 with the document illumination lamp 3004 turned on. Operations such as shading correction are the same as those for platen reading in a method in which a document image is read by being conveyed through a conveyance roller 2005, a registration roller 2007, a read roller 2009, a flow reading glass 3020, a lead discharge roller 2011, and a discharge roller 2013.

  Since the paper conveyance performance greatly affects the quality of the flow reading, the DF2000 is provided with a plurality of configurations for supporting the conveyance.

  Specifically, a width direction regulating plate 2003 that regulates the width direction of the document to ensure sheet feeding stability, a separation pad 2006 that separates the sheet bundle, a resist driven roller 2008 for stabilizing the transportability, and a lead driven. A roller 2010 and a lead discharge driven roller 2012.

  The 3-line image sensor 3011 is composed of three RGB RGB photodiode arrays, and FIG. 22 is a diagram illustrating a general structure thereof.

  In FIG. 3, three photodiodes 3100, 3101 and 3102 (hereinafter referred to as PD) coated with filters of RED, GREEN and BLUE (hereinafter referred to as PD) have shift gates (hereinafter referred to as SH gates) for reading out stored charges on both sides, and transfer registers. Are arranged, and odd-numbered pixels and even-numbered pixels are each distributed to one side and output.

  The SH gate is provided independently for each color (the SH1 gate 3110 for the RED PD 3100, the SH2 gate 3111 for the GREEN PD 3101, and the SH3 gate 3112 for the BLUE PD 3102), and can be driven independently.

  Each transfer register 3120 to 3125 is driven in common by two drive pulses φ1 and φ2 that are inverted during the transfer period. In FIG. 22, the charges are horizontally transferred to the right side, and output amplifiers 3130 to 3 connected to the respective transfer registers. The voltage is converted by 3135 and output.

  Since the PDs are arranged at intervals of 4 lines, the timing for reading the same line of the document is different between PDs, and there is a phase difference of 4 lines between BLUE and GREEN and 8 lines between BLUE and RED.

  Specifically, at the time of reading the platen, the document relatively moves in the direction from the RED PD 3100 to the BLUE PD 3102. In addition, since the document transport direction is reversed during flow reading, the relative document movement direction on the three-line sensor is also opposite to the platen reading.

  FIG. 22 is a diagram showing the structure of the CCD line sensor 3011. The CCD line sensor 3011 is a three-line color line sensor composed of three photodiodes coated with RED, GREEN, and BLUE filters.

  The RED photodiode 3100, the GREEN photodiode 3101, and the BLUE photodiode 3102 are arranged at intervals of 4 lines. A shift gate for transferring charges accumulated in the photodiode to the transfer register is arranged on both sides of each photodiode, and one transfer register is arranged outside the shift gate.

  Reference numeral 3110 denotes an SH1 gate disposed adjacent to the RED photodiode 3100, and an SH2 gate 3111 and an SH3 gate 3112 are disposed in GRREN and BLUE, respectively.

  O written in each photodiode is an odd pixel, ● represents an even pixel, and in the case of RED, the odd pixel is passed through the SH1 gate 3110 to the RED odd pixel transfer register 3120, and the even pixel ● is fed through the SH1 gate 3110 The data is transferred to the pixel transfer register 3121 and output.

  The same applies to GRREN and BLUE. The GREEN odd pixel is transferred to the GREEN odd pixel transfer register 3122, the GREEN even pixel is transferred to the GREEN even pixel transfer register, the BLUE odd pixel is transferred to the BLUE odd pixel transfer register 3124, and the BLUE even pixel is transferred to the BLUE even pixel transfer register. The data is transferred to 3125 and output.

  Reference numerals 3130 to 3135 denote output buffers connected to the transfer registers.

  FIG. 24 is a diagram showing an image processing configuration of the image reading device 3000.

  The RED, GREEN, and BLUE signals output from the CCD line sensor 3011 are input to the shading correction circuit 3400. The signals Rs, Gs, and Bs after the shading correction processing are input to the interline correction circuit 3401, and the RGB phase difference is corrected by the interline correction described with reference to FIG.

  The Rl, Gl, and Bl signals output from the interline correction circuit 3401 are input to the image area separation circuit 3402 and the input masking correction circuit 3403.

  The image area separation circuit 3402 outputs a flag signal: Z1 for determining an image area and a character area. The image area separation processing is generally performed in units of pixels.

  The input masking correction circuit 3403 performs processing for mapping the input Rl, Gl, and Bl signals to the standard color space. The mapping process is performed by a plurality of grid points and an interpolation process between the grid points. The Rm, Gm, and Bm signals output from the input masking correction circuit 3403 are input to the LCC conversion circuit 3404 and output as Ca, Cb, and L signals.

  The Ca and Cb signals representing the color difference are input to the saturation detection circuit 3405, and the L signal representing the brightness is input to the filter circuit 3406. The L, Ca, and Cb signals are simultaneously input to the achromatic color determination circuit 3409.

  The saturation detection circuit 3405 detects the saturation of the image data from the color difference signals Ca and Cb, and outputs a saturation signal: s. The filter circuit 3406 is a circuit that performs a filter process on the luminance signal: L, and coefficient switching control is performed by a flag signal: Z1 output from the image area separation circuit 3402.

  Specifically, the character is sharpened, and the image is subjected to processing such as higher gradation or moire removal. The Cax, Cbx, and Lx signals output from the saturation detection circuit 3405 and the filter circuit 3406 are input to the enhancement amount correction circuit 3407.

  The enhancement amount correction circuit 3407 is a circuit that corrects luminance according to the saturation signal: s. The Cay, Cby, and Ly signals output from the enhancement amount correction circuit 3407 are input to the LCC inverse conversion circuit 3408, reconverted into the RGB space, and output.

  Reference numeral 3409 denotes an achromatic color determination circuit which outputs an achromatic color flag signal: Z2 for determining whether the image data is an achromatic color or a chromatic color. Achromatic flag signal: Z2 is a binary signal in which the achromatic portion is 0 and the chromatic portion is 1.

  Reference numeral 3410 denotes a counter which counts the achromatic flag signal: Z2 over the entire surface of the document, and the count result is used to determine whether the document is a color document or a monochrome document.

  Through the above processing, the read image data is calibrated to the standard RGB space, and image quality correction such as moire removal and edge enhancement is performed by various correction processes. At the same time, a process for determining whether the document type is color or monochrome is performed.

  FIG. 23 shows an image read by the CCD line sensor 3011. FIG. 23A shows an original image, and FIG. 23B shows an image read by the CCD line sensor 3011.

  The CCD line sensor 3011 is an RGB three-line color sensor with an interval of 4 lines. Since the original is read by moving scanning, the timing for reading the same line of the original has a time difference of 4 lines between the RGB. Accordingly, a phase difference of 4 lines is generated in an image read by each PD of RED, GREEN, and BLUE.

  FIG. 23C shows an image after correcting the phase difference of the four lines. The four-line phase difference correction is performed using a FIFO memory or the like, and it can be seen that the phase difference generated in FIG. 23B is corrected.

  FIG. 23D is an enlarged view of FIG. 23C in the sub-scanning direction. Even after correction of the line interval, 0.1 line is provided between RED and BLUE, and 0.2 is provided between RED and GREEN. It shows that there is a phase difference between the lines.

  This is caused by vibration in the sub-scanning direction generated during the RGB reading time difference.

  Thus, the phase difference between RGB generated in the sub-scanning direction is called color shift and is one of the causes of image quality deterioration.

  The vibration in the image reading apparatus is mainly generated by the optical motor and affects the first mirror base, the second mirror base, and the like. In general, it is known that the distance between photodiodes in a CCD line sensor is closely related to color shift. This is because the smaller the line spacing, the higher the frequency component of the vibration that causes color misregistration, and the mechanical frequency component of the vibration generated in the device, mainly the low frequency component. Is related to

  FIG. 25 shows the relationship between the photodiode interval of the CCD line sensor and the color misregistration amount, and it can be seen that the color misregistration amount decreases as the photodiode interval decreases. Accordingly, it is very important to reduce the distance between the photodiodes of the CCD line sensor in order to reduce the color shift.

  In order to reduce the distance between the photodiodes of the CCD line sensor, the photodiode transfer registers on both sides are disposed outside the photodiodes, and only the center photodiode transfer register is disposed between the photodiodes. (For example, refer to Patent Document 1) or a method of disposing the photodiode transfer register at one end outside the photodiode and the other two photodiode transfer registers outside the PD at the other end (for example, (See Patent Document 2), a method is known in which the number of transfer registers arranged between photodiodes is reduced to reduce the interval between photodiodes.

  On the other hand, color reproducibility is raised as another important parameter for determining the image quality of the image reading apparatus. The color reproducibility is greatly influenced by the color filter mounted on the CCD line sensor, and the color separation characteristic of the color filter is a major point how much the color matching function that reproduces human cone sensitivity can be reproduced. In general, a color filter mounted on a CCD line sensor cannot reproduce a color matching function.

  As a means for improving the color reproducibility, there is known a method of providing a fourth color filter in addition to the three color filters and improving the color reproducibility by arithmetic processing. As a specific example, a digital camera manufactured by SONY A four color CCD sensor is mounted on the DSC-F828.

  In this digital camera, a fourth color filter called an emerald is provided in a part of the pixels where the green filter is conventionally arranged, and the color reproducibility is improved while performing pixel information without the filter by interpolation processing. (For example, refer nonpatent literature 1).

Since the image data obtained by such interpolation processing is different from the original image information, it may cause problems such as generation of false colors, but it is practically used in an image reading apparatus using an area image sensor such as a digital camera. It is not a problem.
JP-A-8-274294, page 5, FIG. Japanese Patent Laid-Open No. 10-93763, page 8, FIG. Gakken "Sony Cybershot F828 Superbook" p22

  An image reading apparatus using an image sensor has the following two steady problems.

  One is to reduce the distance between the photodiodes in the line image sensor, and the other is to improve the color separation characteristics of the image sensor.

  However, since the four-color technique described in the background art is premised on interpolation processing for improving color separation characteristics, an image reading apparatus using a line image sensor performs image area separation and saturation detection in units of pixels. In such a process, it becomes a factor causing erroneous determination.

  Further, the increase in the number of signals due to the four colors complicates the image processing and increases the apparatus cost.

  In view of the above situation, an object of the present invention is to propose a line image sensor that achieves both a reduction in the interval between photodiodes and an improvement in color separation characteristics, and realizes high image quality in an image reading apparatus using the line image sensor. It is to be.

  The present invention provides a line image sensor provided with the following means.

  A photodiode group composed of four or more types of photodiode arrays, a color filter mounted on each photodiode array and having different color separation characteristics, a synthesis means for synthesizing at least two charges, and synthesis By arranging a plurality of photodiode rows synthesized by means at the end of the photodiode group, it is ideal by synthesizing charges generated with different color separation characteristics while reducing the line interval between the photodiodes. The present invention provides a CCD line sensor that realizes excellent color separation characteristics.

  By implementing the present invention, it is possible to realize an image reading apparatus that achieves both improved color reproducibility and reduced color misregistration. More specifically, the line sensor proposed by the present invention can realize any color separation characteristics, reduce distortion in color calibration processing, reduce image quality degradation such as pseudo contour, and reduce color shift due to vibration. By doing so, there is an effect that high image quality can be realized.

  FIG. 1 is a structural diagram of a CCD line sensor 100 proposed by the present invention. Reference numeral 100 denotes a CCD line sensor having four photodiodes (hereinafter referred to as PD), PD101 is a BLUE color filter, PD102 is a GREEN color filter, PD103 is a RED color filter, and PD104 is a second BLUE color filter. have.

  O and ● shown in each PD indicate odd-numbered pixels and even-numbered pixels, and solid arrows indicate correspondence with transfer registers.

  The CCD line sensor 100 is mounted on the image reading device 6000 shown in FIG. 90. FIG. 9 is the same as the image reading device 3000 described in FIG. 21, and only the CCD line sensor is different from that the DF2000 is not mounted. It is a configuration.

  The charge accumulated in the PD 101 of BLUE is read out by the SH1 gate 110, ST1 gate 120, ST2 gate 121, transfer registers 140, 141, and TG1 gate 130 provided outside. The accumulated charge is first read by the SH1 gate 110 and temporarily stored in the ST1 gate 120 and ST2 gate 121.

  The ST1 gate 120 and the ST2 gate 121 are storage gates for distributing the odd and even pixels of the BLUE PD 101, the ST1 gate 120 is associated with the odd pixel accumulated charge, and the ST2 gate 121 is associated with the even pixel accumulated charge. ing.

  The accumulated charges of the odd pixels stored in the ST1 gate 120 are once transferred to the transfer register 141 disposed on the inner side, and then transferred to the outer transfer register 140 through the TG1 gate 130.

  On the other hand, the even pixel charges stored in the ST2 gate 121 are transferred to the transfer register 141 disposed inside. The transfer registers 140 and 141 are registers that perform charge transfer in the direction indicated by the frame arrows. The transferred charges are supplied to the output amplifiers 151 and 152, respectively, are converted into voltages, and are output.

  The stored charge of the GREEN PD 102 is read out by the SH2 gate 111 and the transfer registers 142 and 143 arranged on both sides and between the BLUE PD 101 and the RED PD 101, respectively. The accumulated charges are read out in the direction of the transfer register 142 by the SH2 gates 111 arranged on both sides, and the even-numbered pixel charges are read in the direction of the transfer register 143.

  The operations of the transfer registers 142 and 143 and the output amplifiers 153 and 154 are the same as those of the transfer registers 140 and 141 and the output amplifiers 151 and 152 described above, transfer charges in the direction of the frame arrow, convert the voltages, and output them.

  The distance between the GREEN PD 102 and the BLUE PD 101 and the RED PD 103 on both sides thereof is a distance corresponding to two lines because one transfer register is provided between them.

  The accumulated charge of the RED PD 103 is transferred to the second BLUE PD 104 disposed on the opposite side of the GREEN PD 102 through the ST3 gate 122 and the SH3 gate 113, and the charge addition is performed on a pixel basis.

  Since the ST3 gate 122 is a read storage gate and is configured to hold the charge for one line accumulated in the RED PD 103, the distance between the RED PD 103 and the second BLUE PD 104 is also a distance of two lines. It becomes.

  The charge accumulated and added by the PD 104 of the second BLUE is read by the SH4 gate 114, ST4 gate 125, ST5 gate 124, transfer registers 144 and 145, and TG2 gate 131 provided outside. The accumulated charge is first read by the SH4 gate 114 and temporarily stored by the ST4 gate 123 and ST5 gate 124, and then the odd pixel charge is transferred to the transfer register 145 through the ST5 gate 124, transfer register 144, and TG2 gate 131. Is transferred from the ST4 gate 123 to the transfer register 144. The operations of the SH4 gate 113, the ST4 gate 123, the ST5 gate 124, the transfer register 144, the TG2 gate 131, the transfer register 145, and the output amplifiers 155 and 156 are the same as those of the reading configuration of the BLUE PD 101.

  Next, the color filter mounted on each PD will be described. FIG. 2 shows the spectral characteristics of the color filters of each PD, (1) is the BLUE PD101, (2) is the GREEN PD102, (3) is the RED PD103, and (4) is the second BLUE PD104 characteristic. It is.

  FIG. 2 (5) shows spectral characteristics realized by charge synthesis of PD 103 and PD 104. The spectral characteristics of FIGS. 2 (1), 2 (2), and 2 (5) are CIE (International Commission on Illumination). This is equivalent to the spectral characteristic of the xyz coordinate system established in (1) and realizes a color matching function.

  The mixing ratio of the RED PD 103 and the second BLUE PD 104 is adjusted by the application amount of each filter, and the mixing ratio is appropriately adjusted including the characteristics of the document illumination lamp 3004. The color matching function to be realized is not limited to the xyz coordinates, and the spectral characteristics of each PD may be changed as appropriate.

  FIG. 3 is a timing chart for driving the CCD line sensor 100. The drive timing is composed of a blanking period in which charges are transferred from each PD to the transfer register, and a horizontal transfer period in which the transfer registers are driven horizontally to output read charges.

  One line period is a value obtained by the apparatus, and reading is performed by repeating this period. The blanking period is composed of timings from a to n, and charge transfer in each period will be described with reference to FIGS.

  FIG. 4 is a diagram showing the gate structure of the CCD line sensor 100 in detail, and the same numbers as those in FIG. The ST1 gate 120 and the ST2 gate 121 are alternately arranged, and the ST4 gate 125 and the ST5 gate 124 are the same. Each ST gate is designed to transfer charges to the φ1 gate of the transfer register.

  The transfer registers 140, 141, 142, 143, 144, and 145 are configured by repeating two gates of φ1 and φ2, and perform horizontal transfer of charges by applying two-phase pulses of different polarities to the φ1 gate and φ2 gate. Is. The TG1 gate 130 and the TG2 gate 131 are disposed between the φ1 gates.

  FIG. 5 is a charge flow diagram showing the movement of charges during the blanking period. Hereinafter, the charge flow will be described in association with the timing chart. FIG. 5A shows a state after the accumulation of one line is completed, and is an initial state of the blanking period.

  In the figure, a circle indicates a signal charge generated by exposure with a PD. The ones marked with ● represent surplus charges left after the horizontal transfer. Each PD holds a charge accumulated by one line of exposure. Characteristic is the PD 104 of the second BLUE, which holds the charge accumulated in the PD 103 of the RED two lines before and the charge accumulated in the PD 104 of the second BLUE.

  The ST3 gate 122 holds the charge accumulated in the RED PD 103 one line before. Since the ST3 gate 122 is subjected to a light shielding process, no charge is added. In the transfer registers 140 to 145, the TG gates 130 to 131, and the ST gates 120 to 125, surplus charges after the completion of the horizontal transfer are generated.

  The surplus charge generated in the transfer registers 140 to 145 is such that empty transfer pixels outside the signal area are sequentially accumulated in each stage of the transfer register, and increase according to the number of stages.

  Therefore, it is characterized by increasing in accordance with the horizontal transfer direction.

  On the other hand, surplus charges generated in the TG gates 130 to 131 and the ST gates 120 to 125 are accumulated according to one line period and are uniform in all the gates. In this state, the ST1 gate 120, the ST2 gate 121, the ST4 gate 125, the ST5 gate 124, and the φ1 gate are turned on, and the charge arrangement state shown in FIG.

  FIG. 5B shows the first stage of the surplus charge sweeping operation on both sides. When the ST1 gate 120, ST2 gate 121, ST4 gate 125, and ST5 gate 124 are turned off, the φ1 gates of the inner transfer registers 141 and 144 are turned on. Excess charge transfer is performed. On the other hand, the TG1 gate 130 and the TG2 gate 131 are turned on, and preparation for receiving charges from the φ1 gate is performed.

  In FIG. 5C, surplus charges are transferred to the TG1 gate 130 and the TG2 gate 131 by turning off the φ1 gate.

  In FIG. 5D, when the TG1 gate 130 and the TG2 gate 131 are turned off and the φ1 gate is turned on, surplus charges are transferred from the TG gate to the φ1 gates of the outer transfer registers 140 and 145.

  In FIG. 6 (e), the CLR1 gate 160 and the CLR2 gate 161 are turned on, and preparations for sweeping away excess charge are made. Since the φ1 gate remains in the ON state, charge transfer is not performed.

  In FIG. 6F, the φ1 gate is turned OFF, and the surplus charge is swept away to the CLR gate.

  The surplus charges generated in the ST gates, TG gates, and transfer registers on both sides in the operations so far are cleared. The surplus charge is cleared for the purpose of eliminating the surplus charge non-uniformity between the transfer registers.

  As described above, the surplus charge generated in the transfer register increases in the horizontal transfer direction. In the signal charge transfer described later, when transferring the charge from the inner transfer register 141 to the outer transfer register 140, if the surplus charge is also transferred at the same time, the excess charge component between the inner transfer register 141 and the outer transfer register 140 is transferred. Unevenness occurs.

  Therefore, the non-uniformity of the surplus charge component can be removed by performing the surplus charge sweeping operation described so far. The same applies to the transfer registers 144 and 145.

  On the other hand, the surplus charges generated in the central transfer registers 142 and 143 have uniform characteristics over the entire area by combining the surplus charge components generated in the signal charge transfer operation, and therefore, the surplus charge sweeping operation is necessary. And not.

  The signal charge transfer operation is started from FIG. First, the ST1 gate 120, the ST2 gate 121, the ST4 gate 125, the ST5 gate 124, and the φ1 gate are turned on, and the gate side preparation for the charge transfer from each PD is performed.

  In FIG. 6 (h), the SH1 gate 110, the SH2 gate 111, and the SH4 gate 114 are turned on, the odd pixel charge from the BLUE PD 101 to the ST1 gate 120, the even pixel charge to the ST2 gate 121, and the odd number from the GREEN PD102. The pixel charge is transferred to the transfer register 142, the even pixel charge is transferred to the transfer register 143, the odd pixel charge is transferred from the second BLUE PD 104 to the ST5 gate 124, and the even pixel charge is transferred to the ST4 gate 125.

  In FIG. 7I, the SH1 gate 110, the SH2 gate 111, and the SH4 gate 114 are turned off, and the charge transfer from the PD is completed. At this timing, the PDs 101, 102, and 104 start the next charge accumulation.

  In FIG. 7 (j), the ST1 gate 120 and the ST5 gate 124 are turned OFF, and charge transfer to the φ1 gate of the inner transfer registers 141 and 144 is started. At the same time, the SH3 gate 113 is turned on, the RED charge one line before held in the ST3 gate 122 is transferred to the PD 104 of the second BLUE, and pixel addition is started.

  In FIG. 7 (k), the TG1 gate 130 and the TG2 gate 131 are turned ON, and preparation for charge transfer from the φ1 gate of the inner transfer registers 141 and 144 is performed.

  In FIG. 7L, the φ1 gate is turned off, and charge transfer from the inner transfer registers 141 and 144 to the TG1 gate 130 and the TG2 gate 131 is performed. At the same time, the SH3 gate 113 is also turned off, and the charge transfer from the ST3 gate 122 to the PD 104 of the second BLUE is also completed.

  In FIG. 8 (m), when the TG1 gate 130 and the TG2 gate 131 are turned OFF and the φ1 gate is turned ON, the charge transfer is performed from the TG1 gate 130 and the TG2 gate 131 to the φ1 gate of the outer transfer registers 140 and 145. At the same time, the ST3 gate 122 is turned on, and the transfer of the signal charge held in the PD 103 of the RED to the ST3 gate 122 is started.

  In FIG. 8 (n), the ST2 gate 121 and the ST4 gate 125 are turned OFF, and the even-numbered pixel charges held in the ST2 gate 121 and ST4 gate 125 are transferred to the φ1 gates of the inner transfer registers 141 and 144, respectively. Is completed.

  Image reading is performed using the CCD line sensor 100 described above.

  The CCD line sensor 100 is arranged on the image reading device 6000 so that the PD 101 of BLUE is on the upper side. When attention is paid to the same line of the document, the moving direction of the image reading device 6000 moves from the PD 101 to the PD 104. Is driven in the direction of arrow A in FIG.

  FIG. 10 shows the relationship between each PD and the charge held in the ST3 gate 122 during image reading. Since each PD is arranged at intervals of two lines, the document reading lines are also read at intervals of two lines. The charge accumulated in the PD 103 of the RED is once transferred to the ST3 gate 122 as described with reference to FIG. 5, held for one line period, and then transferred to the PD 104 of the second BLUE. Accordingly, in FIG. 10, the ST3 gate 122 holds the charge delayed by one line with respect to the PD 103 of the RED.

  Since the output configuration of the CCD line sensor 100 is the same as the conventional example and has a 6-channel configuration, the image processing configuration is the same as the conventional example shown in FIG. In the CCD line sensor 100, the accumulated charge of the PD 103 of the RED and the accumulated charge of the PD 104 of the second BLUE are added and mixed for each pixel, so that all the color components have all pixel information. Accordingly, since it is not necessary to interpolate the missing pixel by the interpolation process, the pixel unit determination can be performed with sufficient accuracy in the image area separation and the saturation determination process.

  In addition, since the CCD line sensor 100 realizes ideal color separation characteristics, the input masking correction circuit 3403 does not require nonlinear processing, and ideal color reproduction is achieved by linear calculation between Rl, Gl, and Bl signals. Characteristics can be realized.

  As described above, the color separation characteristics of the CCD line sensor 100 are not limited to the xyz coordinate system, and in particular, in combination with the document illumination lamp 3004, to realize the color reproduction performance required for the image reading device 6000. You may adjust suitably.

Furthermore, since the CCD line sensor 100 is configured with two PD intervals, the vibration frequency affected by the four-line interval described in the background art can be shifted to a higher region. Therefore, it is possible to reduce a component that causes a color shift with respect to vibrations of the system, and it is possible to provide an image reading apparatus that is strong against vibrations.
(Example 2)

  As a second embodiment of the present invention, a bidirectional CCD line sensor effective for the image reading apparatus that provides the flow reading and the platen reading shown in FIG. 21 will be described.

  FIG. 11 is a structural diagram of a bidirectional CCD line sensor 1000 capable of bidirectional reading. The same reference numerals are assigned to the same name portions as those of the CCD line sensor 100 described in the first embodiment.

  The bidirectional CCD line sensor 1000 has a total of four PDs, a BLUE PD 101, a GREEN PD 102, a RED PD 103, and a second BLUE PD 104, and is mounted on the image reading apparatus 7000 shown in FIG.

  The image reading device 7000 is obtained by replacing the bidirectional CCD line sensor of the image reading device 3000 described with reference to FIG. 21, and the other configurations are the same.

  The bi-directional CCD line sensor 1000 is arranged so that the second BLUE PD 104 faces upward. In the case of platen reading, the original moves relatively from the second BLUE PD 104 to the BLUE PD 101, and the flow reading is performed. In this case, conversely, reading is performed in which the original moves relatively from the BLUE PD 101 in the second BLUE PD 104 direction.

  In FIG. 11, the charge accumulated in the PD 101 of BLUE is read by the SH11 gate 1010 and transfer registers 1020 and 1021 provided outside.

  The transfer registers 1020 and 1021 are arranged on the left and right with respect to the center of the line sensor. The transfer register 1020 transfers the left half charge to the left, and the transfer register 1021 transfers the right half charge to the right. ing. Therefore, the left half signal is a mirror image output.

  Transfer of accumulated charges is first read by the SH11 gate 1010, transferred to the φ1 gate of the transfer registers 1020 and 1021, and then output amplifiers 1031 and 1032 by the transfer registers 1020 and 1021 driven in two phases by φ1 and φ2 pulses. The voltage is converted and output.

  Reading of the charges accumulated in the PD of GREEN is performed by the SH12 gate 1011 and transfer registers 1023 and 1022 arranged on the PD 101 side of BLUE. The transfer method is the same as that of the PD 101 of BLUE.

  An SH12 gate 1011 and transfer registers 1022 and 1023 are arranged between the green PD 102 and the blue PD 101, but the transfer registers 1022 and 1023 are arranged on the left and right with respect to the center of the line sensor. There is one transfer register. Accordingly, the interval between the PDs can be reduced, and in this example, an interval of two lines is realized.

  Reading of the accumulated charge of the RED PD 103 is performed by the following two methods.

  One is a method using an SH13 gate 1012 and transfer registers 1024 and 1025 arranged on the green PD102 side, which is the same as the reading method of the BLUE PD101 and the green PD102.

  This method is used in platen reading, and the accumulated charge read from the RED PD 103 becomes the added charge of the RED PD 103 and the second BLUE PD 104. Since the gate configuration disposed between the RED PD 103 and the GREEN PD 102 is the same as the configuration between the GREEN PD 102 and the BLUE PD 101, this interval also realizes a two-line interval.

  The other is a system in which charges are transferred to the PD 104 of the second BLUE and added through the SH14 gate 1013, the ST11 gate 1009, and the SH15 gate 1014 arranged on the PD 104 side of the second BLUE. This is used in flow reading.

  The gate structure arranged between the PD 103 of the RED and the PD 104 of the second BLUE is different from the structure between the other PDs, but the interval is configured with a two-line interval as in the other PDs. .

  Although the detailed timing will be described later, the charge read from the RED PD 103 is held for one line in the ST11 gate 1009 in accordance with the conveyance of the original, and then transferred to the second BLUE PD 104 through the SH15 gate 1014. .

  The stored charge readout of the second BLUE PD 104 is also performed in two ways, similar to the RED PD 103. One is a method using an SH16 gate 1015 and transfer registers 1026 and 1027 arranged on the outside, which is the same as the reading method of the BLUE PD 101 and the GREEN PD 102. This method is used in flow reading, and the accumulated charge read from the second BLUE PD 104 becomes the added charge of the RED PD 103 and the second BLUE PD 104.

  The other is a system in which charges are transferred to the PD 103 of the RED through the SH14 gate 1013, the ST11 gate 1009, and the SH15 gate 1014 disposed on the PD 103 side of the RED, and added. This is the method used when reading the platen.

  Although the detailed timing will be described later, the charge read from the second BLUE PD 104 is adjusted in accordance with the conveyance of the original document, in contrast to the charge transfer from the RED PD 103 to the second BLUE PD 104 during the flow reading. Then, one line is held in the ST11 gate 1009 and then transferred to the RED PD 103 through the SH14 gate 1013.

  Accordingly, the added charges of the PD 103 of the RED and the PD 104 of the second BLUE are transferred using different transfer registers for the flow reading and the platen reading. Specifically, during platen reading, the voltage is converted by the output amplifiers 1034 and 1035 using the transfer registers 1024 and 1025 and input to one input terminal of each of the switches 1040 and 1041.

  At the time of the flow reading, the voltage is converted by the output amplifiers 1036 and 1037 using the transfer registers 1026 and 1027 and input to the other input terminals of the switches 1040 and 1041, respectively.

  The switches 1040 and 1041 are controlled by the SW1 signal, and the platen reading is selected at the Lo level and the flow reading signal is selected at the Hi level.

  With the above structure, the interval between the PDs is 2 line intervals, and the output signals are output on a total of 6 channels, 2 channels for each color regardless of platen reading and flow reading.

  The color filter mounted on each PD is the same as that in the first embodiment, and a description thereof is omitted in this example. FIG. 12 is a timing chart for driving the bidirectional CCD line sensor 1000.

  As described with reference to the structure diagram, the bidirectional CCD line sensor 1000 is driven at two timings in order to transfer different charges between platen reading and flow reading. FIG. 12 (1) shows the timing for platen reading, and FIG. 12 (2) shows the timing for flow reading.

  The timing chart includes a blanking period in which charges are transferred from each PD to the transfer register, and an output horizontal period in which the transfer register is horizontally driven to output read charges. One line period is a value obtained by the apparatus, and reading is performed by repeating this period.

  The blanking period is composed of timings from p to x, and the charge flow at each timing is shown in FIGS.

  13 to 15 are charge transfer flowcharts during flow reading, and FIG. 16 is a charge transfer flowchart during platen reading.

  First, the operation during platen reading will be described. Timing (p) is a state in which the charge accumulation in the previous line is completed in the initial state of charge transfer. The BLUE PD 101, the GREEN PD 102, and the second BLUE PD 104 each hold the accumulated charge of one line before, and the ST11 gate 1009 stores the accumulated charge in the second BLUE PD 104 two lines before. The RED PD 103 holds the charge generated by the RED PD 103 one line before and the sum of the charges accumulated by the second BLUE PD 104 three lines before.

  At timing (q), the SH11 gate 1010, the SH12 gate 1011 and the SH13 gate 1012 are turned ON, and the charges accumulated in the BLUE PD101, the GREEN PD102, and the RED PD103 are transferred to the transfer registers 1020, 1021, 1022, 1023 and 1024, respectively. 1025, the transfer is started.

  At timing (r), the SH11 gate 1010, the SH12 gate 1011 and the SH13 gate 1012 are turned off, and the charge transfer to the transfer register is completed. At the same time, charge accumulation is started in the BLUE PD101, the GREEN PD102, and the RED PD103. The

  At timing (s), the SH14 gate 1013 is turned ON, and the transfer of the charge accumulated in the second BLUE PD 104 to the RED PD 103 two lines before the ST11 gate 1009 was held is started. Additive synthesis with the accumulated charge is performed.

  At timing (t), the SH14 gate 1013 is turned OFF, and the charge transfer from the ST11 gate 1009 to the PD 103 of the RED is completed. At timing (u), the ST11 gate 1009 is turned ON, and preparation for charge transfer from the PD 104 of the second BLUE is performed. In this state, no charge is transferred.

  At timing (v), the SH15 gate 1014 is turned on while the ST11 gate 1009 remains ON, and charge transfer from the second BLUE PD 104 to the ST11 gate 1009 is started.

  At timing (w), the SH15 gate 1014 is turned OFF, and the charge transfer from the second BLUE PD 104 to the ST11 gate 1009 is completed. At the same time, the charge accumulation of the next line is started in the PD 104 of the second BLUE.

  At timing (x), the ST11 gate 1009 is turned off, and charge transfer in the blanking period is completed. In the platen reading, the SH16 gate 1015 and the transfer registers 1026 and 1027 are not used.

  Next, the operation at the time of flow reading will be described. Timing (p) is a state in which the charge accumulation in the previous line is completed in the initial state of charge transfer.

  The BLUE PD 101, the GREEN PD 102, and the RED PD 103 each hold the accumulated charge of one line before, and the ST11 gate 1009 holds the accumulated charge in the RED PD 103 two lines before. The BLUE PD 104 holds the charge generated by the second BLUE PD 104 one line before and the added charge accumulated by the RED PD 103 three lines before.

  At timing (q), the SH11 gate 1010, SH12 gate 1011 and SH16 gate 1015 are turned on, and the charges accumulated in the BLUE PD 101, the GREEN PD 102, and the second BLUE PD 104 are transferred to the transfer registers 1020, 1021, 1022, respectively. Transfer is started at 1023, 1026, and 1027.

  At timing (r), the SH11 gate 1010, the SH12 gate 1011 and the SH16 gate 1015 are turned off, and the charge transfer to the transfer register is completed, and the BLUE PD101, the GREEN PD102, and the second BLUE PD104 are next charged. Is started.

  At the timing (s), the SH15 gate 1014 is turned ON, and the transfer of the charge accumulated in the RED PD 103 two lines before held in the ST11 gate 1009 is started to the second BLUE PD 104, and the second BLUE Are added and combined with the charge accumulated in the PD 1003.

  At timing (t), the SH15 gate 1014 is turned OFF, and the charge transfer from the ST11 gate 1009 to the PD 104 of the second BLUE is completed.

  At timing (u), the ST11 gate 1009 is turned on, and preparation for charge transfer from the RED PD 103 is performed. In this state, no charge is transferred.

  At timing (v), the SH11 gate 1013 is turned on while the ST11 gate 1009 remains ON, and charge transfer from the PD 103 of the RED to the ST11 gate 1009 is started.

  At timing (w), the SH14 gate 1013 is turned OFF, and the charge transfer from the PD 103 of the RED to the ST11 gate 1009 is completed. At the same time, charge accumulation in the next line is started in the PD 103 of the RED.

  At timing (x), the ST11 gate 1009 is turned off, and charge transfer in the blanking period is completed.

  The SH13 gate 1012 and the transfer registers 1024 and 1025 are not used in the flow reading.

  The above is the description of the driving timing and the charge flow in the bidirectional CCD line sensor 1000.

  FIG. 20 is a timing chart showing the relationship between the lines in the flow reading and the platen reading. FIG. 20 (1) is the platen reading, FIG. 20 (2) is the accumulation of the original line and each PD in the flow reading, It shows the relationship of the charge to be performed.

  In FIG. 20 (1), when reading the platen, since the original is conveyed from the second BLUE PD 104 of the bidirectional CCD line sensor 1000 toward the BLUE PD 101, the line 1 of the original is read first by the second BLUE PD 104. And read in the order of the RED PD 103, the GREEN PD 102, and the BLUE PD 101 at intervals of two lines.

  Since the ST11 gate 1009 operates to hold the charge accumulated in the PD 104 of the second BLUE for one line period, the timing is delayed by one line with respect to the PD 104 of the second BLUE.

  Since the output of the bi-directional CCD line sensor 1000 is a signal output from the RED PD 103, the GREEN PD 102, and the BLUE PD 101, the RED PD 103 output and the BLUE PD 101 output are 4 lines, the GREEN PD 102 output and the BLUE PD 101 output. The PD101 output has a phase difference of two lines.

  In order to read the original at the timing when the BLUE PD101 output signal is the slowest, the RED PD103 output is delayed by 4 lines and the GREEN PD102 is delayed by 2 lines in the subsequent interline correction circuit, and phase correction is performed.

  20 (2), since the original is transported from the BLUE PD 101 of the bidirectional CCD line sensor 1000 in the direction of the second BLUE PD 104, the line 1 of the original is first read by the BLUE PD 101. GREEN PD102, RED PD103, and BLUE PD101 are read in the order of two lines.

  Since the ST11 gate 1009 operates to hold the charge accumulated in the RED PD 103 for one line period, the ST11 gate 1009 is delayed by one line with respect to the RED PD 103.

  Since the output of the bidirectional CCD line sensor 1000 is a signal output from the second BLUE PD 104, the green PD 102, and the BLUE PD 101, the BLUE PD 101 output and the second BLUE PD 104 output are 6 lines. The PD 102 output and the second BLUE PD 104 have a phase difference of 4 lines.

  Since the second BLUE PD104 output signal is read at the latest timing, the subsequent line-to-line correction circuit performs delay processing for 6 lines for the BLUE PD101 output and 4 lines for the GREEN PD102, and phase correction is performed. Done.

  The phase relationship depends on the arrangement of the bidirectional CCD line sensor mounted on the image reading device 7000, but is not limited in this example. In other words, the bidirectional CCD line sensor 1000 may be arranged upside down with respect to the image reading device 7000, that is, the BLUE PD 101 may be placed on the upper side. The timing and phase control only need to be performed in reverse.

  As described above, a bidirectional CCD line sensor that achieves both a reduction in the line interval and an improvement in color separation characteristics in all pixels is realized even in an image reading apparatus in which the document transport direction differs between platen reading and flow reading. I can do it. As a result, it is possible to provide an image reading apparatus in which a component that causes a color shift with respect to vibration is reduced and color reproducibility is improved.

Example 1 Structure of CCD line sensor 100 FIG. 5 is a diagram illustrating color separation characteristics of the CCD line sensor 100 according to the first embodiment. Embodiment 1, drive timing chart of CCD line sensor 100 Example 1, Detailed gate structure of CCD line sensor 100 Example 1 Charge Transfer Flow Diagram of CCD Line Sensor 100 Example 1 Charge Transfer Flow Diagram of CCD Line Sensor 100 Example 1 Charge Transfer Flow Diagram of CCD Line Sensor 100 Example 1 Charge Transfer Flow Diagram of CCD Line Sensor 100 First Embodiment, Structure of Image Reading Device 6000 Example 1, line timing chart of CCD line sensor 100 Example 2 Structure of Bidirectional CCD Line Sensor 1000 Second Embodiment, Bidirectional CCD Line Sensor 1000 Timing Chart Example 2 Charge Transfer Flow Diagram During Flow Reading Operation of Bidirectional CCD Line Sensor 1000 Example 2 Charge Transfer Flow Diagram During Flow Reading Operation of Bidirectional CCD Line Sensor 1000 Example 2 Charge Transfer Flow Diagram During Flow Reading Operation of Bidirectional CCD Line Sensor 1000 Example 2 Flowchart of Charge Transfer when Reading Platen in Bidirectional CCD Line Sensor 1000 Example 2 Flowchart of Charge Transfer when Reading Platen in Bidirectional CCD Line Sensor 1000 Example 2 Flowchart of Charge Transfer when Reading Platen in Bidirectional CCD Line Sensor 1000 Second Embodiment, Structure of Image Reading Device 7000 Example 2 Line Timing Chart of Bidirectional CCD Line Sensor 1000 The figure which shows a prior art example and an image reading apparatus Structure of conventional example, CCD line sensor 3011 Figure showing a conventional example and a scanned image Conventional example, image processing block diagram Conventional example, a diagram showing the relationship between CCD line spacing and color misregistration

Explanation of symbols

100 CCD line sensor 101 BLUE PD
102 GREEN PD
103 RED PD
104 Second BLUE PD
1000 Bidirectional CCD line sensor 3001 Document glass 3002 Reference white plate 3003 Document pressure plate 3004 Document illumination lamp 3005 First mirror 3006 Second mirror 3007 Third mirror 3008 First mirror table 3009 Second mirror table 3010 Optical lens 3011 CCD line sensor 3012 Optical Motor 3013 First reflection shade 3014 Second reflection shade 3100 RED photodiode 3101 GREEN photodiode 3102 BLUE photodiode 3401 Interline correction circuit 3402 Image area separation circuit 3403 Color space correction circuit 3404 LCC conversion circuit 3405 Saturation detection circuit 3406 Filter circuit 3407 Enhancement amount correction circuit 3408 LCC inverse conversion circuit 3409 Achromatic color determination circuit 3410 Counter

Claims (3)

  A photodiode group composed of four or more types of photodiode arrays, a color filter mounted on the photodiode array and having different color separation characteristics, and charges generated by at least two of the photodiode arrays are synthesized. A CCD line image sensor, comprising: a combining unit; and a plurality of photodiode rows combined by the first combining unit are arranged at an end of the photodiode group.   2. The CCD line image sensor according to claim 1, wherein the synthesizing means has a TDI (Time Delay Integration) structure.   2. The CCD line image sensor according to claim 1, wherein a direction in which the synthesizing unit synthesizes charges is equal to a document conveying direction.

Images