JP4093164B2 - Image reading apparatus, image reading method, and drive control apparatus - Google Patents

Description

  The present invention relates to an image reading apparatus, an image reading method, and a drive control apparatus. More specifically, the present invention relates to a technique for reducing power consumption and heat generation of a sensor device in an apparatus having at least a function of reading an image, such as a scanner apparatus, a copying apparatus, a facsimile apparatus, or a multifunction machine having these functions.

  In an apparatus having a function of reading an original image, such as a scanner apparatus or a copying apparatus, as means for optically reading an original image, for example, a CCD (Charge Coupled Device) or a CMOS (Complementary Metal-oxide Semiconductor) is used. A solid-state imaging device is used.

  These solid-state imaging devices operate by receiving a predetermined driving pulse, and consume electric power and generate heat in accordance with the operation. Although the CMOS sensor has relatively low power consumption and low heat generation, the CCD sensor has relatively high power consumption and high heat generation.

  For example, in recent years, as an image reading apparatus used for a copying machine, a scanner apparatus, etc., one line sensor is provided, and in addition to an apparatus for reading a monochrome image (mainly a monochrome image), a color image can be read. Is spreading. In such a color image reading apparatus, a solid-state imaging device having a three-line configuration (for example, three lines) corresponding to the respective color components of R (red), G (green), and B (blue), which are the three primary colors of light. An image is read using a light receiving unit having a CCD sensor. Therefore, in the light receiving portion, power consumption and heat generation are increased for color than for monochrome.

  In addition, recently, the number of line sensors has further increased to meet various reading requirements (see, for example, Patent Documents 1 to 3). For example, in Patent Document 1, as a solid-state imaging device used for an image reading apparatus, in addition to sensors for three lines corresponding to RGB color components, a sensor for one line for monochrome image reading is provided. A four-line configuration has been proposed. If the number of line sensors increases, power consumption and heat generation further increase in the light receiving unit. When a CMOS is used as the sensor, the increase in power consumption and heat generation is relatively small. However, when a CCD is used, the increase in power consumption and heat generation is very large.

JP 2003-87503 A Japanese Patent No. 3083013 Japanese Patent No. 3155842

  Therefore, as a technique for solving the problems of power consumption and heat generation during standby, it is not necessary to drive these solid-state imaging devices in a standby state in which optical information is not read. It is known to employ a method of driving at a voltage lower than normal (see, for example, Patent Documents 4 and 5).

JP-A-6-141132 JP 2000-299770 A

  For example, Patent Document 4 proposes a mechanism in which the power supply to the CCD and the CCD driver is cut off during standby for reading the CCD to suppress the temperature rise of the CCD and the CCD driver. Further, Patent Document 5 discloses that a CCD driving transfer clock is stopped and supplied repeatedly at certain intervals during reading standby, thereby suppressing current consumption during standby and a CCD sensor after starting driving from a reading standby state. A mechanism has been proposed to shorten the rise time.

  By using the techniques described in Patent Documents 4 and 5, for example, the CCD power supply voltage is lowered and the CCD drive clock is stopped during standby, thereby reducing the temperature rise of the CCD and the CCD driver (drive circuit). In addition, when the star button is pressed and the platen cover is opened, the power supply voltage can be raised to the normal voltage, and the CCD drive clock can be supplied to bring the CCD into an operating state.

  However, using the techniques described in Patent Documents 4 and 5 can solve the problems of power consumption and heat generation, but it has been found that a new problem occurs when attempting to read the document again. .

  For example, in the techniques described in Patent Documents 4 and 5, optical information is read from the outside by detecting a user's switch operation or when a document is inserted into a document insertion slot or when a platen cover is opened. It is determined that a command has been input, and only at this time, the solid-state imaging device is driven. In addition, if the platen cover is left open, the temperature rise of the solid-state imaging device and the drive circuit becomes too large. Therefore, in the techniques described in Patent Documents 4 and 5, the CCD and the like are mounted after a certain period of time. I was trying to put it on standby.

  Therefore, when the next reading is started from a state in which the platen cover is left open, an apparatus that performs document detection (such as detection of document size or monochrome / color document type) using a solid-state imaging device. In this case, there arises a problem that the next document detection does not work immediately. This is because when the platen cover is closed, the document cannot be detected because the solid-state imaging device is not operating.

  Even if the solid-state imaging device is activated while it is completely closed by detecting the operation of closing the platen cover, it takes a rise time until the solid-state imaging device can read the optical information. It is difficult to perform proper document detection.

  The present invention has been made in view of the above circumstances, and in an apparatus for reading optical information using an imaging apparatus such as a CCD, power consumption and heat generation during standby can be reduced, and a solid-state imaging apparatus is provided. It is an object of the present invention to propose a mechanism that can always prevent inconvenience even when document detection is performed.

  An image reading method according to the present invention is an image reading method for reading a document using at least one of a plurality of sensors including a photosensitive portion, and in a standby state waiting for a document reading instruction, The power supply to the plurality of sensors is controlled so that at least one of the plurality of sensors is in an operating state and the remaining sensors are in a non-operating state, and a driving pulse signal to the plurality of sensors is controlled. We decided to control the supply.

  An image reading apparatus according to the present invention is an apparatus suitable for carrying out the image reading method according to the present invention. First, as an image acquisition unit, a light receiving unit having a plurality of sensors each including a photosensitive unit. And a drive control unit that controls supply of power to the plurality of sensors and also controls supply of a driving pulse signal to the plurality of sensors. In the standby state waiting for the document reading instruction, the drive control unit sets the power supply so that at least one of the plurality of sensors is in an operating state and the remaining sensors are in a non-operating state. Controls the supply of pulse signals.

  The drive control device according to the present invention corresponds to a drive control unit constituting the image reading device according to the present invention.

  The invention described in the dependent claims defines further advantageous specific examples of the image reading apparatus and the drive control apparatus according to the present invention.

  According to the present invention, since at least one sensor is in an operating state and the remaining sensors are in a non-operating state in a standby state that shifts when a predetermined time has elapsed without performing reading, Compared to the operation state, power consumption and heat generation in the standby state can be reduced. Even in the standby state, a desired signal such as document detection can be obtained using one sensor in the operation state. Processing can be performed without inconvenience.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<First Embodiment>
FIG. 1 is a side sectional view showing an outline of an embodiment of an image reading apparatus according to the present invention. The image reading device 3 is used for, for example, a copying machine, a scanner device, a facsimile device, and the like, and optically reads an image drawn on the original from a sheet-like original to be read. In general, the image acquisition unit 10, the image processing unit 20, and an ADF (Automatic Document Feeder) device 60 having a circulation function and having functions of a platen cover are provided.

  The image acquisition unit 10 includes a casing 111 and a platen glass (original placement table) 112 that is made of transparent glass provided on the casing 111 and is slightly larger than the A3 size on which an original to be read is placed. have. The image processing unit 20 is provided on a substrate 102 provided in the housing 111.

  The image reading device 3 is configured to be able to select and use a fixed reading method and a conveyance reading method depending on whether or not the ADF device 60 provided on the platen glass 112 is used. The ADF device 60 does not have a circulation function, but an automatic document feeder (DADF) having a circulation function can also be used.

  As a mechanism for detecting the opening / closing operation of the ADF device 60 having the function of the platen cover, a platen opening / closing sensor 117 is provided in the vicinity of a portion serving as a fulcrum of the opening / closing operation (the deepest part on the left side of the paper). The platen opening / closing signal SP detected by the platen opening / closing sensor 117 is sent to a drive control unit 150 (to be described later) in addition to the image processing unit 20.

  In addition, document sensors 118 that detect the size of the document are provided at several locations on the lower surface of the platen glass 112. The document sensor 118 optically detects the leading edge of the document, for example, at a position corresponding to the size of the document to obtain a size detection signal, and sends the size detection signal to the image processing unit 20. In the present embodiment, the document sensor 118 is used to determine the document size in the sub-scanning direction, and automatically specifies the document size in the sub-scanning direction.

  For example, in the drawing, four document sensors 118 are arranged to form a document size detection unit, but two of the A3 end sides of these are along a side registration guide SRG (not shown) (that is, in the sub-scanning direction). Are arranged in different positions). One of them (lead register guide LRG side) mainly functions to detect B5 horizontal placement and the other functions to detect A4 horizontal placement. The two on the lead registration guide LRG side are arranged at different positions in the drawing depth direction and the sub-scanning direction. One of them (lead register guide LRG side) mainly functions to detect B5 vertical placement and the other functions to detect A4 vertical placement. Further, by determining the combination of detection results of the document sensor 118, B4 landscape orientation or A3 landscape orientation can be detected.

  On the other hand, regarding the document size in the main scanning direction, the document size in the main scanning direction is automatically specified by using a line sensor constituting a light receiving unit 140 that reads the document, which will be described later. The document size is not limited to such automatic detection, and the user may specify the document size by specifying the size from the user interface, for example.

  The image acquisition unit 10 emits light from a light source 120 that emits light toward a surface (back surface) opposite to the document placement surface of the platen glass 112 below the platen glass 112 in the housing 111. A full rate having a substantially concave reflecting shade 131 and a reflecting mirror 132 for reflecting the reflected light toward the platen glass 112, and a reflecting mirror 134a for deflecting the reflected light from the platen glass 112 in a direction substantially parallel to the platen glass 112 A carriage (F / R-CRG) 134 is provided.

  As the light source 120, a fluorescent lamp whose longitudinal direction is the main scanning direction (the direction orthogonal to the paper surface in the figure) is used. As the color of the illumination light emitted from the light source 120, a color that matches the spectral optical characteristics of each line sensor constituting the light receiving unit 140 is used. For example, white light or green light is used.

  The image acquisition unit 10 has two reflection mirrors 136a and 136b arranged so as to form a substantially right angle in the casing 111, and sequentially deflects the reflected light deflected by the full rate carriage 134 by about 90 °. A half-rate carriage (H / R-CRG) 138 is provided. The full rate carriage 134 and the half rate carriage 138 are configured to reciprocate in the sub-scanning direction (in the direction of arrow X in FIG. 1) and in the opposite direction in conjunction with a stepping motor (not shown).

  In addition, the image acquisition unit 10 receives the reflected light deflected by the reflection mirror 136b in the casing 111 at a predetermined focal position, and the reflected light converged by the lens 139, and receives the reflected light in the sub-scanning direction. And a light receiving unit 140 that sequentially reads an image signal (analog electrical signal) corresponding to the density.

  The light receiving unit 140 is a line sensor (not shown) composed of a photoelectric conversion element such as a photodiode, a CCD (Charge Coupled Device), a CMOS (Complementary Metal-oxide Semiconductor), and the like disposed on the substrate 103. ) Or a processing by a read signal processing unit 14 including a drive control unit 150 such as a CCD driver for driving a line sensor, which is also disposed on the substrate 103, and then sent to the image processing unit 20.

  Although not shown, the image acquisition unit 10 also includes a wire, a drive pulley, and the like for moving the reading optical system, the light receiving unit 140, and the like under the platen glass 112 in the housing 111. The drive pulley is reciprocally rotated by the drive force of the drive motor, and the wire is wound around the drive pulley by the rotation drive, so that the full-rate carriage 134 including the light source 120, the half-rate carriage 138, or A reading optical system including a lens 139 is moved at a predetermined speed.

  The ADF device 60 includes a document setting unit 62, a document discharge unit 63, and various conveyance roll pairs 64 such as a registration roll pair 64a and an exit roll pair 64b for forming a document conveyance path. A guide 113 is provided at the end (left side in the figure) of the platen glass 112 at the top of the housing 111, and a light-transmissive contact glass (reading glass) 114 is provided in the immediate vicinity thereof.

  A guide 115 is provided on the contact glass 114. A white reference plate 116 is included in the guide 113. In addition, a sheet sensor 65 for detecting a document is provided at a plurality of predetermined positions on the conveyance path in the ADF device 60. By monitoring the detection output of the paper sensor 65, the leading edge or the trailing edge of the document can be detected in the document conveyance process using the ADF device 60.

  In the above configuration, the full-rate carriage 134 of the image acquisition unit 10 constituting the reading optical system is normally at a home position H indicated by a Δ mark in the drawing below the platen glass 112. Thus, in the fixed reading method, the document placed on the platen glass 112 by the line sensor provided in the light receiving unit 140 without moving the light receiving unit 140 in the sub-scanning direction before starting the reading. The size in the main scanning direction can be detected.

  In the conveyance reading method, the ADF apparatus 60 conveys the document while the full rate carriage 134 is fixed (stop-locked) below the contact glass 114 on the document conveyance path by the ADF apparatus 60. While reading the image.

  For example, the full-rate carriage 134 moves under the platen glass 112 from the home position H in the direction opposite to the arrow X or while performing exposure scanning, and is stopped and locked at a conveyance reading image destination position C indicated by a Δ mark in the drawing. The processing unit 14 and the light receiving unit 140 are set in an imaging standby state. Thereafter, when an exposure start permission signal is transmitted from the main body CPU (not shown) to the ADF device 60, the ADF device 60 that has received the permission signal starts feeding the document placed on the document setting unit 62. To do.

  When the original is guided in the direction of the guides 113 and 115 through a predetermined conveyance path composed of various conveyance roll pairs 64, passes through the registration roll pair 64a, and reaches the conveyance reading image destination position C, the ADF apparatus By reading the image destination signal from the 60 side to the image acquisition unit 10 side, reading of the document image is started. The conveying roll pair 64 such as the resist roll pair 64a and the exit roll pair 64b is controlled to have a constant peripheral speed by a drive motor (not shown), whereby the document passes over the guides 113 and 115 at a substantially constant speed. Then, it passes through the exit roll pair 64b and is discharged in the direction of the document discharge portion 63. That is, the image reading device 3 performs image reading corresponding to a so-called CVT (Constant Velocity Transfer) method in which a document image is read while conveying a document to be read at a constant speed.

  On the other hand, at the time of the fixed reading method, a document is manually placed on the platen glass 112 as a document placement table (the ADF device 60 may be used) and fixed at an arbitrary position on the platen glass 112 (stop lock). In this state, the scanning optical system is moved at a constant speed in the direction of the arrow X with the fixed reading image destination position F indicated by the Δ mark in the figure as a reference, and the document is exposed to read the image.

  For example, in a state where the document placed on the platen glass 112 is covered with the ADF device 60, the light from the light source 120 irradiates the document placed on the platen glass 112, and the reflected light is emitted from the full rate carriage 134, half The light is split into red, green, and blue colors via a reading optical system including a rate carriage 138 and a lens 139. Each color light is incident on a corresponding line sensor divided for each color light, and the input image is read at a predetermined resolution, so that the captured image signal of each spectral component, for example, red, green, blue An analog captured image signal of each color component is obtained.

  At the time of reading, the illumination light from the light source 120 irradiates the entire surface of the document, and the light receiving unit 140 reads the input image over the entire surface via the reading optical system such as the lens 139 so that the full rate including the light source 120 is included. The reading optical system including the carriage 134, the half-rate carriage 138, the lens 139, and the like, the light receiving unit 140, and the like are relatively moved at a constant speed from left to right (sub scanning direction) in FIG. It is done. That is, the image reading device 3 reads a document image while moving the optical system at a constant speed.

  In this way, each original image in the conveyance reading method or the fixed reading method is changed in the optical path by the full rate carriage 134 or the half rate carriage 138, is reduced by the lens 139, and reaches the light receiving unit 140. The light receiving unit 140 sends captured image signals of each spectral component obtained by capturing a document image with a line sensor to the read signal processing unit 14. The read signal processing unit 14 performs desired analog signal processing on the captured image signal obtained by the reading, and then converts the digital image data of each color component of red (R), green (G), and blue (B). The digital image data of red, green and blue is converted and sent to the image processing unit 20.

<Configuration of light receiving unit>
FIG. 2 is a diagram illustrating a configuration example of the light receiving unit 140. The light receiving unit 140 has three line sensors 142R, 142G, and 142B (corresponding to the three colors R, G, and B so that the components of the three colors R, G, and B can be detected for color image capturing. The reference element indicates a color component) and a single line sensor 142K for monochrome (white / black) image capturing. The line sensors 142R, 142G, 142B, and 142K are collectively referred to as a line sensor 142. These line sensors 142R, 142G, 142B, 142K are arranged so as to be read in the order of K, R, G, B in the sub-scanning direction.

  Each line sensor 142 is configured by arranging a large number of photosensitive portions having a pixel size of 7 μm × 7 μm in an array corresponding to one line in the main scanning direction. That is, in the package of the light receiving unit 140, line sensors 142 in which n photosensitive units having a pixel size of 7 μm × 7 μm are arranged are arranged in four rows on the semiconductor substrate 141 at a predetermined interval. Each of these line sensors 142 is means for reading a document image at each reading position in the sub-scanning direction. Each photosensitive unit includes a photoelectric conversion element such as a photodiode that photoelectrically converts incident light, and a charge storage unit that accumulates charges generated by the photoelectric conversion element.

  In the figure, 1, 2, 3,..., N attached to the line sensor 142 indicate pixel numbers in the main scanning direction. In the present embodiment, the main scanning direction at the time of color imaging is opposite to the main scanning direction at the time of monochrome imaging.

  Here, the line sensors 142R, 142G, 142B for color image capturing are separated by L1 μm. Correspondingly, the reading positions of the respective color components in the sub-scanning direction on the document transport path are separated by L2 μm. Each original image (each line image for one line) at each reading position is reduced by L1 / L2 times through the reading optical system shown in FIG. 1 and is applied to each line sensor 142R, 142G, 142B, 142K. To form an image. That is, the distance L1 between the three line sensors 142 corresponds to the distance L2 at the document position before being focused by the lens 139, and the three line sensors 142 simultaneously read the positions of the document at a distance L2. In the present embodiment, L1 is made equal to one line, that is, the pixel pitch for ease of gap correction and the like.

  Further, the line sensor 142G located at the center of the line sensors 142R, 142G, and 142B for color image capturing and the line sensor 142K for monochrome image capturing are separated by L3 μm. Correspondingly, the reading positions of the respective color components in the sub-scanning direction on the document transport path are separated by L4 μm. Each original image (line image corresponding to one line) at each reading position is reduced by L3 / L4 times through the reading optical system shown in FIG. 1 and is applied to each line sensor 142R, 142G, 142B, 142K. To form an image. That is, the distance L3 between the line sensors 142G and 142K corresponds to the distance L4 at the original position before being focused by the lens 139, and the line sensors 142R, 142G, and 142B for color image capturing and the monochrome image capturing. The line sensor 142K simultaneously reads a position L4 away from the document. In this embodiment, L3 is set to 12 lines.

  Note that the distance L1 between the line sensors 142R, 142G, and 142B for color image capturing and the distance L3 between the line sensors 142G and 142K are not limited to the above-described example, and are appropriately determined in consideration of the entire configuration of the image reading device 3. May be.

  Of these four-line line sensors 142, color filters corresponding to the R, B, and B color components are separately provided on the light receiving surfaces of the three line sensors 142R, 142G, and 142B. Thereby, these line sensors 142R, 142G, and 142B function as means for reading an optical image for each of the RGB color components for capturing a color image.

  For example, when arranged so as to be read in the order of R, G, and B in the sub-scanning direction, the R line sensor 142R has n photons constituting the line sensor 142R every one line period (main scanning period). The charges accumulated in the diode are transferred to the transfer register by the vertical transfer pulse, the charges in the transfer register are sequentially transferred horizontally by the horizontal transfer clock, and the charge voltage is converted by the final stage amplifier for one line (for n pixels). Are output as an analog imaging signal SR representing the density of each pixel.

  Similarly, in the G line sensor 142G corresponding to the reading position downstream of the line sensor 142R, the charges accumulated in the n photodiodes are vertically transferred every line cycle (main scanning cycle). The pulse is transferred to the transfer register, the charge of the transfer register is sequentially transferred horizontally by the horizontal transfer clock, the charge voltage is converted by the final stage amplifier, and an analog signal representing the density of each pixel for one line (n pixels) An imaging signal SG is output. Further, also in the B line sensor 142B corresponding to the reading position downstream of the line sensor 142G, the charge accumulated in the n photodiodes is transferred vertically for each line period (main scanning period). Is transferred to the transfer register, and the charge of the transfer register is sequentially transferred horizontally by the horizontal transfer clock, and the charge / voltage conversion is performed by the final stage amplifier, and analog imaging representing the density of each pixel for one line (for n pixels) Signal SB is output.

  On the other hand, the other line sensor 142K may have a configuration in which a color filter is not provided on the light receiving surface, or one of the three color components handled by the three line sensors 142R, 142G, 142B. You may provide the color filter corresponding to a component (for example, G color component which the line sensor 142G takes charge). In the latter case, the line sensor 142K functions as a means for reading an optical image for one of the three color components handled by the three line sensors 142R, 142G, 142B.

  Also in the monochrome imaging line sensor 142K corresponding to the reading position on the upstream side of the color line sensor 142R, the charges accumulated in the n photodiodes are vertically transferred every line cycle (main scanning cycle). An analog representing the density of each pixel for one line (n pixels) by transferring to the transfer register by a transfer pulse, sequentially transferring the charge of the transfer register horizontally by a horizontal transfer clock, and converting the charge to voltage by a final stage amplifier. Imaging signal SK is output.

  Here, if a line sensor 142K provided with a color filter corresponding to the G color component similar to that of the line sensor 142G is used, the line sensor 142K uses a color filter corresponding to the G color component during monochrome imaging. Therefore, the sensor sensitivity of the line sensor 142K for monochrome imaging and the line sensors 142R, 142G, 142B for color imaging are not greatly different from each other.

  That is, unlike the four-line configuration that uses a line sensor 142K that does not have a filter, the exposure cycle of each line sensor 142 and the light amount of the light source 120 are set without considering the output saturation of the line sensor 142K for black and white. Therefore, it is possible to obtain a large RGB output from the color line sensor 142, and as a result, the S / N of the RGB output can be prevented from deteriorating. Therefore, good reading can be realized for both monochrome images and color images.

<Details of light receiving unit configuration>
FIG. 3 is a block diagram illustrating a functional configuration of the light receiving unit 140. A CCD is used as the line sensor 142 forming the light receiving unit 140 of the present embodiment. Here, the three transfer sensors 144Ra, 144Rb, 144Ga, 144Gb, 144Ba, 144Bb (collectively referred to as transfer registers 144) are attached to the three line sensors 142R, 142G, 142B corresponding to the RGB color components, respectively. Thus, odd (ODD) pixels and even (EVEN) pixels can be distributed and output in parallel.

  Output amplifiers 148Ra, 148Rb, 148Ga, 148Gb, 148Ba, and 148Bb each having a charge / voltage conversion function and an amplification function are provided in the final stage (left side in the figure) of each transfer register 144, respectively. Yes.

  On the other hand, for one monochrome line sensor 142K, four transfer registers 142Ka, 142Kb, 142Kc, and 142Kd are attached, thereby the first pixel (4j-3; j is a positive integer of 1 or more), The second pixel (4j-2), the third pixel (4j-1), and the fourth pixel (4j) can be distributed and output in parallel. Output amplifiers 148Ka, 148Kb having a charge / voltage converting function and an amplifying function are respectively provided at the last stage of the transfer registers 142Ka to 142Kd in the main scanning direction (on the right side in the figure and opposite to the color side). 148Kc and 148Kd are provided.

  The color output amplifiers 148Ra, 148Rb, 148Ga, 148Gb, 148Ba, 148Bb and the monochrome output amplifiers 148Ka, 148Kb, 148Kc, 148Kd are collectively referred to as an output amplifier 148. As the output amplifier 148, for example, a floating diffusion (FDA) configuration that is a diffusion layer having a parasitic capacitance is used.

  When a plurality of lines are arranged for each color component in this way, the number of transfer registers 144 for each line sensor 142 is increased, and good reading is realized in both the color imaging mode and the monochrome imaging mode. In addition to being able to do so, the reading speed can be further increased.

  Between the stages of each transfer register 144, a drive pulse (shift pulse) SH related to vertical transfer (shift operation) for transferring the charge accumulated in the photosensitive portion to the transfer register 144 and about 10 or more kinds of pulse signals (summary). Vertical transfer system pulse PV).

  The individual registers constituting each transfer register 144 include horizontal transfer drive pulses φ1 and φ2 (collectively horizontal transfer systems) related to horizontal transfer in which the signal charges transferred to the transfer register 144 are sequentially transferred to the output amplifier 148 side. Pulse PH).

  The output amplifier 148 is supplied with, for example, an LH signal, an RS signal, and a switching signal SW (collectively referred to as an output system pulse PO) related to signal output.

  In the configuration as described above, when the reflected light from the document enters the light receiving unit 140, each photoelectric conversion element in each line sensor 142 accumulates electric charge according to the received light amount. Thereafter, the signal charges accumulated in each photoelectric conversion element are moved to the corresponding transfer registers 144 by the drive pulse SH given from the outside at a predetermined timing. Then, the signal charge moved to the transfer register 144 is sequentially transferred to the output amplifier 148 side by the external transfer drive pulses φ1 and φ2 from the outside, and transferred to the output amplifier 148 by the LH signal as the final transfer pulse. Then, it is output from the output terminal of the output amplifier 148 to the outside as an output signal.

  At this time, for the color line sensors 142R, 142G, and 142B, ODD and EVEN can be output in parallel by the two transfer registers 144, respectively. On the other hand, unlike the other three line sensors 142R, 142G, and 142B for color, the monochrome line sensor 142K can be output in parallel by the four transfer registers 144a to 144d. Therefore, the signal charge accumulated in the line sensor 142K can be read out at twice the speed for color.

<Signal processing system of image acquisition unit>
FIG. 4 is a block diagram illustrating a functional configuration focusing on the signal processing of the image acquisition unit 10. The image acquisition unit 10 includes a drive control unit 150 that drives the line sensor 142 of the light receiving unit 140, a power supply unit 160 that supplies power to the light receiving unit 140, and a captured image signal acquired by the line sensor 142 of the light receiving unit 140. On the other hand, a reading signal processing unit 14 that performs reading-system signal processing is provided.

  As a specific configuration in the present embodiment, the power supply unit 160 individually supplies power to the line sensors 142R, 142G, 142B of the color imaging system and the line sensor 142K of the monochrome imaging system, and independently turns on / off. Two systems are prepared so that it can be controlled. Each is shown with a reference CL (for color) and K (for monochrome).

  The read signal processing unit 14 provided at the subsequent stage of the light receiving unit 140 is configured to output analog imaged image signals SRa and SRb (collectively referred to as SR) and SGa at predetermined reading positions captured by the line sensors 142 for the respective color components. , SBb (collectively referred to as SG), SBa, SBb (collectively referred to as SB), SKa, SKb, SKc, and SKd (collectively referred to as SK). The circuit includes an analog signal processing unit 170 that performs analog system signal processing such as AGC (Auto Gain Control) and AOC (Auto Offset Control).

  In addition, the read signal processing unit 14 includes an A / D conversion unit 180 that converts an analog signal into digital data and a digital data obtained by the A / D conversion unit 180 after the analog signal processing unit 170. For example, the image processing unit 190 performs a shading correction, a synchronization process for correcting RGBK delay, and the like. As functional parts for performing shading correction, for example, a subtracting circuit, a RAM, a multiplying circuit, and a dividing circuit are included.

  Two systems are prepared for the monochrome system analog signal processing section 160 and the A / D conversion section 170. Each functional unit provided in the read signal processing unit 14 is shown with reference elements R, G, B, K (K1 and K2) corresponding to the color components R, G, B, K.

  The drive control unit 150 sets a driving cycle of the line sensor 142, controls the gain of the output amplifiers 148R, 148G, 148B, and 148K, controls the shading correction circuit, and the like. Unit) 152 and a clock generation unit 154 that generates a master clock signal that serves as a reference for the driving cycle.

  Further, the drive control unit 150, based on the clock signal CLK from the clock generation unit 154, the clock necessary for the operation of each unit, the vertical transfer system pulse PV for driving the line sensor 142, the horizontal transfer system pulse PH, or A timing generator 156 that generates a pulse signal at a predetermined timing, such as an output system pulse PO, and a drive unit 158 that supplies the pulse signal generated by the timing generator 156 to the line sensor 142 are provided.

  The central control unit 152 receives signals from the paper sensor 65, the platen open / close sensor 117, or the reading start button of the operation unit, and the like, for example, whether reading is in progress or waiting. Based on the result, the timing generator 156 and the power supply unit 160 are turned on / off, that is, the power supply to the line sensor 142 and the supply / non-supply of drive pulses are controlled.

  Here, as a specific configuration in the present embodiment, the timing generator 156 and the drive unit 158 include a line sensor 142R, 142G, 142B corresponding to a processing block of a color imaging system and a line sensor corresponding to a processing block of a monochrome imaging system. Individual functional units are prepared so that 142K can be independently (individually) operated and not operated. Each is shown with a reference CL (for color) and K (for monochrome).

  In this configuration, first, each line sensor 142 of the light receiving unit 140 is driven by a drive pulse from the drive control unit 150 to read a document image at a predetermined reading position on the document conveyance path, and at the reading position. Imaging signals SR, SG, SB, and SK are output. The analog signal processing unit 170 samples the picked-up image signals SRa, SRb, SGa, SGb, SBa, SBb, and SKa to SKd supplied from the line sensors 142 of the light receiving unit 140 by corresponding sample and hold circuits. Thereafter, each signal is amplified to an appropriate level by a corresponding output amplifier circuit.

  Further, the analog signal processing unit 170 includes a synthesis circuit, and pixel signals based on signal charges transferred from the two transfer registers 144 corresponding to the line sensors 142R, 142G, and 142B output from the output amplifier circuit, respectively. And ODD and EVEN are alternately arranged. As a result, the analog image signal processing units 170R, 170G, and 170B for color output one set of captured image signals SR, SG, and SB, respectively, and pass them to the corresponding A / D conversion units 180R, 180G, and 180B.

  On the other hand, for the monochrome system, output signals based on signal charges transferred by two transfer registers 144Ka, 144Kb or 144Kc, 144Kd are handled, and pixel signals are synthesized in each of them so that ODD and EVEN are alternately arranged. To. As a result, the two monochrome captured image signals SK1 and SK2 are output from the monochrome analog signal processing unit 170K and passed to the corresponding A / D conversion units 180K1 and 180K2.

  The A / D converter 180 converts the analog captured image signals SR, SG, SB, SK1, SK2 input from the corresponding analog signal processor 170 into digital data DR, DG, DB, DK1, DK2, The image is transferred to the image processing unit 190.

  The image processing unit 190 uses the corresponding shading correction circuit to correct pixel sensitivity variations of the corresponding line sensor 142 and the light amount of the reading optical system for these five systems of digital image data DR, DG, DB, DK1, DK2. In order to perform correction corresponding to the distribution characteristics, signal processing such as AGC (Auto Gain Control) and AOC (Auto Offset Control) is performed, and processed data DR, DG, DB, DK1 and DK2 are transferred to the synchronization processing unit.

  Here, the line sensor 142 is driven by a drive signal from the drive control unit 150, thereby reading a document image at each reading position on the document transport path, and imaging signals SR, SG,. SB is output. As described above, the four line sensors 142 simultaneously read the positions of the document that are separated by L2 or L4, and the monochrome line sensor 142K on the most upstream side in the document transport direction (that is, the sub-scanning direction). Reading in advance.

  For this reason, regarding the imaging signals SR, SG, SB (or image data DR, DG, DB) read by the color line sensors 142R, 142G, 142B on the downstream side, the color imaging image signals SR, SG, SB are used. (Or image data DR, DG, DB) is a signal at the same position as the imaging signals SK1, SK2 (or image data DK1, DK2) read by the upstream line sensor 142K before the document is conveyed by approximately L4. .

  The same thing occurs also between the line sensors 142R, 142G, 142B for color images. For the image signals SG, SB (or image data DG, DB) read by the downstream line sensors 142G, 142B, the captured image The signal SG (or image data DG) is a signal at the same position as the image pickup signal SR (or image data DR) read by the upstream line sensor 142R before the document is conveyed by L2, and the image pickup image signal SB (or The image data DB) is a signal at the same position as the imaging signal SR (or image data DR) read by the upstream line sensor 142R before the document is conveyed by 2 × L2.

  Based on this, in the synchronization processing unit in the image processing unit 190, first, the RGB delay interval of the line sensors 142 (= L1) or the monochrome color line interval (= L1) in the RGB delay correction circuit. = L3) By correcting the delay of the image data, a synchronization process is performed so as to indicate signals at the same position in the sub-scanning direction (that is, physically the same position) at the same output timing.

  In addition to these, the image processing unit 190 includes, for example, a lookup table (LUT), a color space conversion circuit, and the like. The look-up table and the color space conversion circuit are for converting the output signal from the line sensor 142 into a combination of a lightness signal and a color signal. The image processing unit 190 uses the look-up table for each of the RGB image data DR1, DG1, and DB1 synchronized by the delay correction circuit, and converts the color brightness data DL * and the color data Da * and Db *. Generate. Further, the image processing unit 190 has a monochrome composition circuit as a monochrome signal processing circuit. This monochrome synthesis circuit generates monochrome brightness data DL * by synthesizing the image data DK1 and DK2.

<Power consumption / heat generation reduction method>
FIG. 5 is a diagram illustrating a mechanism for reducing power consumption and heat generation of the line sensor 142 during standby in relation to document detection using the line sensor 142.

  As shown in FIG. 5A, in this embodiment, the platen opening / closing sensor 117 is used to detect the opening / closing operation of the ADF device 60 having the function of the platen cover. The platen opening / closing signal SP detected by the platen opening / closing sensor 117 is notified to the central control unit 152 of the drive control unit 150.

  A white plate is provided on the platen glass 112 side of the platen cover so that the outer edge of the document can be easily detected. The image reading apparatus 3 according to the present embodiment is configured to detect the size of the document in the main scanning direction by using the line sensor 142. As a mechanism thereof, when the platen cover is opened, The detection is performed in two stages when it is closed.

  In this way, when the platen cover is first opened, the document size is detected in the main scanning direction with the background being substantially black, so that the document size in the main scanning direction is detected for a substantially white-colored document. When the platen cover is closed, the background is the color of the platen cover (in this example, white) and the original size is detected in the main scanning direction, so that a black image is formed at the edge of the original. Even in this case, it is possible to accurately detect the document size in the main scanning direction for the document.

  The central control unit 152 refers to the platen opening / closing signal SP from the platen opening / closing sensor 117, supplies power to the monochrome line sensor 142K by the monochrome power supply unit 160K of the power supply unit 160, and performs color use by the color power supply unit 160CL. The power supply to the line sensors 142R, 142G, 142B (collectively 142CL) is controlled. Further, supply of drive pulses to the monochrome line sensor 142K by the monochrome timing generator 156K and supply of drive pulses to the color line sensors 142R, 142G, 142B by the color timing generator 156CL are controlled.

  FIG. 5 (B) summarizes aspects of controlling the power supply and drive pulse supply to each line sensor 142.

  In the present embodiment, first, the central control unit 152 operates the color line sensor 142CL and the monochrome line sensor 142K of the light receiving unit 140 individually while the image acquisition unit 10 is in a standby period (standby). Select. The standby period is divided into two modes: 1) a state in which the platen cover is closed, and 2) a state in which the platen cover is opened, and the power supply and the supply of drive pulses are controlled according to each state.

  Specifically, first, when the platen cover is closed, in order to detect the document using the line sensor 142, the platen cover is first opened, and this is detected by the platen opening / closing sensor 117. After that, if the line sensor 142 is activated, the document detection is sufficiently in time. Therefore, the light receiving unit 140 puts the sensors into a non-operating state for both the monochrome line sensor 142K and the color line sensor 142CL, that is, both the color system and the monochrome system.

  In order to put the sensor in a non-operating state, for example, a method of stopping the supply of power and drive pulses to each line sensor 142 or a supply voltage to each line sensor 142 is reduced while supply of drive pulses is stopped. The technique can be taken. The effect of reducing power consumption and heat generation is higher when power supply is completely stopped.

  On the other hand, when the platen cover is open, the platen cover is only closed when the document is detected. Therefore, in order to detect the document in the middle of closing, it is not in time unless the line sensor 142 has been operated before that time. . For this purpose, one of the line sensors 142 in a plurality of rows is set in an operating state, and the original is detected by the line sensor 142 in the operating state.

  Here, which of the plurality of line sensors 142 is preferably in the operating state should be determined by considering the processing blocks of the line sensors 142 and the number of line sensors 142 corresponding to the processing blocks. .

  Considering the processing block, it is preferable that one line sensor 142 in the same processing block is in an operating state and the rest is in a non-operating state. This is because the output characteristics are unbalanced until it becomes stable, which may cause inconvenience in the output image. Therefore, it is preferable to switch between operation and non-operation for each processing block. In this example, the operation / non-operation is preferably switched between the color system and the monochrome system.

  Further, considering the number of line sensors 142 corresponding to the processing block, it is preferable because the effect of reducing power consumption and heat generation is higher as the number of line sensors 142 to be operated is smaller. Therefore, when switching between operation and non-operation for each processing block, the entire processing block with a small number of line sensors 142 corresponding to the processing block may be set to the operating state, and the other processing blocks may be set to the non-operating state. preferable. In this example, it is preferable that the monochrome system of the color system and the monochrome system is in an operating state and the color system is in a non-operating state.

  Note that, on the side to be in the operating state (monochrome system in this example), the drive pulse is supplied as usual while the power supply voltage is supplied as usual. On the other hand, on the non-operating state (color system in this example), as described above, a method of stopping the supply of power and drive pulses to each line sensor 142, A method of stopping the supply of drive pulses while reducing the supply voltage can be adopted, and the effect of reducing power consumption and heat generation is higher when the power supply is completely stopped.

  However, when starting from a state in which the platen cover is open, there is a request to start the sensor more quickly than when starting from a state in which the platen cover is closed, so the effect of reducing power consumption and heat generation is reduced. However, it is also effective to adopt a method of stopping only the supply of drive pulses while supplying the power supply voltage as usual.

  FIG. 6 is a timing chart showing a method of controlling the power supply and drive pulse supply to each line sensor 142. Here, FIG. 6 shows an example in which all of the vertical transfer system pulse PV, the horizontal transfer system pulse PH, and the output system pulse PO are collectively controlled.

  For example, as shown in FIG. 6A, after completion of the reading operation with the platen cover closed, when no operation is performed with the platen cover closed, a predetermined time elapses. That is, even if the light source 120 is turned off and the platen cover sensor 117 is not detected by the platen opening / closing sensor 117 or the original sensor is not detected by the paper sensor 65 even if a predetermined time has elapsed, the image reading device 3 will not read the platen cover. Transition to the standby state when is closed.

  At this time, the central control unit 152 of the drive control unit 150 first stops the power supplied to all the line sensors 142 of the color imaging system and the monochrome imaging system or supplies a voltage that is lower than the normal level. The color power supply unit 160CL and the monochrome power supply unit 160K are controlled.

  The central control unit 152 collectively removes all of the vertical transfer system pulse PV, the horizontal transfer system pulse PH, and the output system pulse PO supplied to all the line sensors 142 of the color imaging system and the monochrome imaging system. The color timing generator 156CL and the monochrome timing generator 156K are controlled so as to be in the supply state.

  Thereafter, when the platen open / close signal SP of the platen open / close sensor 117 indicates that the platen cover is opened, the central control unit 152 first supplies power and drive pulses only for the monochrome system of the color system and the monochrome system. The monochrome timing generator 156K and the monochrome power supply unit 160K are controlled so that the remaining color systems are not operated.

  Thereafter, when the platen opening / closing signal SP of the platen opening / closing sensor 117 indicates that the opening / closing operation of the platen cover has been detected, or when the reading start button is pressed, the central control is performed. The unit 152 controls the color timing generator 156CL and the color power supply unit 160CL so as to supply power and drive pulses for the color system.

  Further, as shown in FIG. 6B, after completion of the reading operation with the platen cover closed, when no operation is performed with the platen cover opened and a predetermined time elapses, that is, Even if the light source 120 is turned off and the platen cover sensor 117 is not detected by the platen opening / closing sensor 117 or the original sensor is not detected by the paper sensor 65 even if a certain time has elapsed, the image reading apparatus 3 opens the platen cover. Transition to the standby state.

  At this time, the central control unit 152 of the drive control unit 150 first stops only the power supplied to the line sensor 142CL of the color imaging system or supplies a voltage lower than the normal level. 160CL is controlled.

  Further, the central control unit 152 collectively removes all of the vertical transfer system pulse PV, horizontal transfer system pulse PH, and output system pulse PO supplied to the color imaging system line sensor 142CL. The color timing generator 156CL is controlled.

  In addition, the central control unit 152 maintains the supply state of the power supplied to the line sensor 142K of the monochrome imaging system, and also maintains the supply state of the drive pulse supplied to the line sensor 142K of the monochrome imaging system.

  Since the monochrome system of the line sensors 142 in a plurality of rows is in the normal operating state, using the monochrome line sensor 142K does not cause any inconvenience even when performing predetermined signal processing during standby, and the platen Even when the reading operation is started when the cover is closed, it is possible to detect the document immediately after the start.

  Thereafter, when the platen opening / closing signal SP of the platen opening / closing sensor 117 indicates that the opening / closing operation of the platen cover has been detected, or when the reading start button is pressed, the central control is performed. The unit 152 controls the color timing generator 156CL and the color power supply unit 160CL so as to supply power and drive pulses for the color system.

  As described above, according to the configuration of the present embodiment, when the platen cover is open during standby, one of the line sensors 142 (in this example, the monochrome system) in a plurality of rows is set in the operating state and remains. (In this example, the color system) is set to the non-operating state, so that power consumption and heat generation during standby can be reduced, and the line that has been in the operating state during standby or immediately after startup There is no inconvenience when performing predetermined signal processing such as document detection using the sensor 142 (monochrome system in this example).

  In the switching control between the non-operation state and the operation state, when the supply / non-supply of the drive pulse is controlled, all of the vertical transfer system pulse PV, the horizontal transfer system pulse PH, and the output system pulse PO are collectively processed. Use a method that controls supply / non-supply with a well-balanced combination of both the effects of reducing power consumption and heat generation, and the response speed until steady operation after overflow or startup, not limited to control. Is also effective.

  For example, a method of controlling supply / non-supply of only the horizontal transfer system pulse PH that is strongly related to the main clock, and always supplying the output system pulse PO and the vertical transfer system pulse PV supplied to the final stage of the sensor. It is good to take. As shown in FIG. 5C, the vertical transfer period by the vertical transfer system pulse PV is also supplied for the horizontal transfer system pulse PH on the non-operating side.

  It is preferable to always supply the vertical transfer system pulse PV to the non-operating state, by transferring the charge accumulated in the photosensitive portion to the transfer register 144 even in the non-operating state. Specifically, the charge storage unit) is prevented from being charged (overflow), and the charge is sequentially discharged to the subsequent stage of the transfer register 144 to prevent the transfer register 144 from being charged (overflow). Thereby, it is possible to speed up the start-up when the optical information is read by the sensor and the image can be output after the driving is started.

  Further, it is preferable to always supply the output system pulse PO on the non-operating side because the DC level of the output amplifier 148 in the floating diffusion configuration can be avoided from being affected by the accumulated charge. is there.

  FIG. 7 is a timing chart showing a method for controlling power supply and drive pulse supply to each line sensor 142 in relation to a combination of drive pulses to be supplied / non-supplied.

  Depending on whether the platen cover is closed or not, controlling the combination of the vertical transfer system pulse PV, the horizontal transfer system pulse PH, and the output system pulse PO can speed up the response when the sensor is in the operating state. Can do.

  For example, in the standby state, the light source 120 is turned off regardless of whether the platen cover is closed or opened. Therefore, the input light from the light source 120 to the light receiving unit 140 is close to zero. Therefore, at the time of standby with the platen cover closed, it may be considered that the input light to the light receiving unit 140 is substantially low.

  Accordingly, as shown in FIG. 6A, when the reading is not completed after the light source 120 is turned off after the reading is completed and the platen cover is closed, the drive control unit 150 is in standby. The horizontal transfer system pulse PH (φ1, φ2) is stopped while maintaining the high and low levels of the pulse in a predetermined relationship, and the vertical transfer system pulse PV and the output system pulse PO are stopped. Controlling the timing generator 156 is not generally inconvenient. This is because there is almost no charge in the light receiving part, so that the charge accumulated in the photosensitive part does not overflow from the photosensitive part or the transfer register 144, and the charge does not accumulate and overflow in the floating diffusion constituting the output amplifier 148. .

  Even in this case, if the vertical transfer system pulse PV or the horizontal transfer system pulse PH is left stopped for a long time, it will overflow sometime due to dark current or the like. When the vertical transfer system pulse PV is input, the horizontal transfer system pulse PH may be input for the next predetermined period (for example, one period). By doing so, overflow can be prevented and power consumption can be reduced only during the stop period of the drive pulse. Also, even if unexpected external light is input during standby, if it is driven by the vertical transfer system pulse PV or the horizontal transfer system pulse PH at regular intervals, it can quickly return to the normal state. Can do.

  On the other hand, when the platen cover is opened, even if the light source 120 is turned off in the standby state, external light is input to the light receiving unit 140. Therefore, it can be considered that the input light to the light receiving unit 140 is considerably high during standby in a state where the platen cover is opened.

  Therefore, as shown in FIG. 6B, when the reading is not finished after the light source 120 is turned off after the reading is finished and the platen cover is opened, a drive control unit 150 is in a standby state. Transition to the state, and the horizontal transfer system pulse PH (φ1, φ2) is stopped while maintaining the high and low levels of the pulse in a predetermined relationship, and when the vertical transfer system pulse PV and the output system pulse PO are stopped, The charge accumulated in the photosensitive portion overflows, and the charge accumulates in the floating diffusion constituting the output amplifier 148 and overflows.

  In order to solve this problem, as shown in FIG. 7, when the platen open / close sensor 117 detects that the platen cover remains open, and the state shifts to the standby state, the central control unit 152 sets the non-operating state. When controlling the color line sensor 142CL of the color system, the supply of the horizontal transfer system pulse PH is stopped, and the color timing generator 156CL is controlled so as to supply the vertical transfer system pulse PV and the output system pulse PO. Specifically, the horizontal transfer pulse PH (φ1, φ2) is stopped while maintaining the high and low levels of the pulse in a predetermined relationship, but the vertical transfer pulse PV and the output pulse PO continue to be driven. It is assumed that the timing generator 156 is controlled. By doing so, it is possible to prevent the charge accumulated in the photosensitive portion from overflowing from the photosensitive portion and the charge from being accumulated in the floating diffusion constituting the output amplifier 148.

  In this case, even when the horizontal transfer system pulse PH is stopped, the charge drained to the transfer register 144 can be swept to the overflow drain by providing the overflow drain structure.

  In the case of not having an overflow drain structure, as shown in FIG. 5C, it is preferable to supply the horizontal transfer system pulse PH in the vertical transfer period by the vertical transfer system pulse PV. By doing so, the stored charge of the transfer register 144 can be transferred to the output amplifier 148 side by a small amount, but can be swept out via the output amplifier 148, and overflow in the transfer register 144 due to external light can be prevented. Can do. Further, since the horizontal transfer system pulse PH is not supplied for the entire period, power consumption can be reduced only during the stop period of the horizontal transfer system pulse PH.

  In this way, by controlling the supply / non-supply of only the horizontal transfer system pulse PH and constantly supplying the output system pulse PO and the vertical transfer system pulse PV, power consumption and heat generation during standby can be reduced. In addition, any of the original detection using the sensor is satisfied without any inconvenience, and the output image characteristics after activation are not adversely affected.

  That is, it is possible to reduce the power consumption and temperature rise of the sensor when the image acquisition unit 10 is on standby. Further, even when starting from a standby state in which the platen cover is open, there is no problem in document size detection.

  In addition, even in the standby state, if the sensor final stage clock, the vertical transfer pulse, and the horizontal transfer pulse PH in the vertical transfer period are supplied, the charge accumulated in the sensor is always discharged to overflow. Since the output amplifier is always in the operating state, the response when the sensor is in the operating state can be increased.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. Various changes or improvements can be added to the above-described embodiment without departing from the gist of the invention, and embodiments to which such changes or improvements are added are also included in the technical scope of the present invention.

  Further, the above embodiments do not limit the invention according to the claims (claims), and all combinations of features described in the embodiments are not necessarily essential to the solution means of the invention. Absent. The embodiments described above include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. Even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, as long as an effect is obtained, a configuration from which these some constituent requirements are deleted can be extracted as an invention.

  For example, in the above embodiment, a plurality of transfer registers 144 are provided for each line sensor 142, but this is not essential, and one transfer register 144 for each line sensor 142 may be provided.

  Further, in the above-described embodiment, in the same manner as that described in Patent Document 1, in addition to the sensor for three lines corresponding to each color component of RGB, a sensor for one line for monochrome image reading is provided. Although an example in which the present invention is applied to a four-line configuration is shown, the above-described embodiment can be applied in the same manner as long as it has a combination of a plurality of sensors. It can also be applied to sensors.

  In the above embodiment, a case where a charge transfer type CCD is used as a sensor has been described. However, other types of sensors such as a CMOS may be used, and even in such a case, at least one sensor is used. In the standby state, the remaining sensors are set in the non-operating state, so that power consumption and heat generation in the standby state can be reduced. The sensor can be used to perform desired signal processing such as document detection without any inconvenience.

  In the above embodiment, an example using a line sensor has been described. However, the same effect as in the above embodiment can be obtained even if the line sensor is replaced with a two-dimensional area sensor.

  Further, in the above-described embodiment, the example in which the non-operation / operation control is performed in units of processing blocks has been described. However, regardless of the unit of processing blocks, at least one sensor is in an operating state and the remaining sensors are in a non-operating state. You may control so that it may do.

1 is a side sectional view showing an outline of an embodiment of an image reading apparatus according to the present invention. It is a figure which shows the structural example of a light-receiving part. It is a block diagram which shows the function structure of a light-receiving part. It is a block diagram which shows the function structure which paid its attention to the signal processing of an image acquisition part. It is a figure explaining the mechanism which reduces the power consumption and heat_generation | fever of a line sensor at the time of standby. It is the timing chart which showed the method of controlling supply of the power supply and drive pulse to each line sensor. 6 is a timing chart showing a method for controlling power supply and drive pulse supply to each line sensor in relation to a combination of drive pulses to be supplied / not supplied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 3 ... Image reading apparatus, 10 ... Image acquisition part, 20 ... Image processing part, 60 ... ADF apparatus, 111 ... Case, 112 ... Platen glass, 113 ... Contact glass, 117 ... Platen opening / closing sensor, 118 ... Document sensor, 119 DESCRIPTION OF SYMBOLS ... Substrate, 120 ... Light source, 134 ... Full rate carriage, 138 ... Half rate carriage, 139 ... Lens, 14 ... Read signal processing unit, 140 ... Light receiving unit, 141 ... Semiconductor substrate, 142 ... Line sensor, 144 ... Transfer register, 148 DESCRIPTION OF SYMBOLS Output amplifier 150 ... Drive control part 152 ... Central control part 154 ... Clock generation part 156 ... Timing generator 158 ... Drive part 160 ... Power supply part 170 ... Analog signal processing part 180 ... A / D conversion Part, 190... Image processing part

Claims (17)

An image reading apparatus having an image acquisition unit for reading a document,
The image acquisition unit controls a light receiving unit having a plurality of sensors provided with a photosensitive unit, power supply to the plurality of sensors, and supply of a driving pulse signal to the plurality of sensors. A drive control unit,
In the standby state waiting for a document reading instruction, the drive control unit sets the power source and the power source so that at least one of the plurality of sensors is in an operating state and the remaining sensors are in a non-operating state. An image reading apparatus that controls supply of the pulse signal. The light receiving unit has a sensor corresponding to a processing block, and is configured to be able to receive control of the power supply and the supply of the pulse signal individually in a processing block unit,
The image reading apparatus according to claim 1, wherein the drive control unit controls the operation state and the non-operation state in units of the processing blocks. 3. The drive control unit according to claim 2, wherein the whole of the sensor block corresponding to the processing block having a smaller number of sensors is set to an operating state, and the whole corresponding to the remaining processing blocks is set to a non-operating state. Image reading device. The light receiving unit includes a color image capturing sensor corresponding to a color image processing block and a monochrome image capturing sensor corresponding to a monochrome image processing block.
The image reading apparatus according to claim 3, wherein the drive control unit puts the entire monochrome image capturing sensor into an operating state and puts the entire color image capturing sensor into a non-operating state. 5. The image reading apparatus according to claim 1, further comprising a document detection function unit configured to detect a document using the sensor. A document placement section for placing a document, a cover for covering the document placed on the document placement section, and an open / close sensor for detecting an open / closed state of the cover,
The document detection function unit detects the document in both a closed state and an open state based on a detection signal from the open / close sensor,
The drive control unit
When the detection signal of the open / close sensor indicates the closed state in the standby state, all of the plurality of sensors are inactivated,
Thereafter, when the detection signal of the open / close sensor indicates a state in which the cover is opened, at least one of the plurality of sensors is in an operating state, and the remaining sensors are maintained in a non-operating state,
6. The image reading apparatus according to claim 5, wherein after receiving a document reading instruction, the supply of the power source and the pulse signal is controlled to operate all of the plurality of sensors. A document placement section for placing a document, a cover for covering the document placed on the document placement section, and an open / close sensor for detecting an open / closed state of the cover,
The document detection function unit detects the document in both a closed state and an open state based on a detection signal from the open / close sensor,
The drive control unit
When the detection signal of the open / close sensor in the standby state indicates a state in which the cover is open, at least one of the plurality of sensors is in an operating state while the remaining sensors are in a non-operating state,
6. The image reading apparatus according to claim 5, wherein after receiving a document reading instruction, the supply of the power source and the pulse signal is controlled to operate all of the plurality of sensors. 8. The image according to claim 6, wherein the drive control unit determines an instruction to read the document when the detection signal of the opening / closing sensor indicates that the opening / closing operation of the cover is detected. Reader. Each of the plurality of sensors is
A plurality of the photosensitive parts are arranged in a one-dimensional or two-dimensional direction,
A transfer register unit that holds charges accumulated in each photosensitive portion based on a vertical transfer system pulse input from the outside and sequentially transfers the held charges based on a horizontal transfer system pulse input from the outside. The image reading apparatus according to claim 1, wherein the image reading apparatus is provided. The drive control unit
10. The image reading apparatus according to claim 9, wherein, during the non-operation state control, the supply of the horizontal transfer system pulse is stopped and the vertical transfer system pulse is supplied. Each of the plurality of sensors has an output amplifier that generates an output signal based on the charge transferred from the transfer register unit, based on an output system pulse input from the outside, at the final stage of the transfer register unit. ,
The image reading apparatus according to claim 10, wherein the drive control unit supplies the horizontal transfer system pulse when the vertical transfer system pulse is active. 12. The drive control unit stops power supplied to the sensor or supplies a voltage that is lower than a normal level to the sensor during the non-operation state control. The image reading apparatus according to any one of the above. A drive control device for controlling power supply to a plurality of sensors and controlling supply of a pulse signal for driving to the plurality of sensors;
A power supply unit that individually supplies power to the plurality of sensors;
A timing generator that individually generates pulse signals for driving supplied to the plurality of sensors,
In the standby state, the power supply and the supply of the pulse signal are controlled so that at least one of the plurality of sensors is in an operating state and the remaining sensors are in a non-operating state. apparatus. Each of the plurality of sensors includes a plurality of the photosensitive portions arranged in a one-dimensional or two-dimensional direction, and is based on a vertical transfer system pulse that is input from the outside with charges accumulated in the photosensitive portions. And having a transfer register unit that sequentially transfers the held charge based on a horizontal transfer system pulse input from the outside,
14. The drive control device according to claim 13, wherein, during the control to be in the non-operating state, the supply of the horizontal transfer system pulse is stopped and the vertical transfer system pulse is supplied. Each of the plurality of sensors has an output amplifier at the final stage of the transfer register unit that generates an output signal based on the charge transferred from the transfer register unit based on an output system pulse input from the outside Because
The drive control device according to claim 14, wherein when the vertical transfer system pulse is active, the horizontal transfer system pulse is supplied. 16. The control according to claim 13, wherein the power supplied to the sensor is stopped or a voltage lower than a normal level is supplied to the sensor during the non-operating state control. The drive control device according to item. An image reading method for reading a document using at least one of a plurality of sensors each including a photosensitive portion,
In a standby state waiting for a document reading instruction, power is supplied to the plurality of sensors so that at least one of the plurality of sensors is in an operating state and the remaining sensors are in a non-operating state. An image reading method characterized by controlling the supply of driving pulse signals to the plurality of sensors.

Images