JP2005277581A - Image reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable performing proper shading correction corresponding to the difference in reading conditions. <P>SOLUTION: A scanner device has a white LED array configured by juxtaposing a plurality of white LEDs as a light source. A first white reference plate 65 and a second white reference plate 66 are attached so that a white reference surface 65a of the reference plate 65 is matched with the position of an original document surface at the time of fixedly reading the original document (first height H1), and a white reference surface 66a of the reference plate 66 is matched with the position of an original document surface at the time of reading the moving image of an original document (second height H2). The reference plate 65 is read when the fixed original document reading is performed in which the original document is placed on a first platen glass 72A to read the image, and the reference plate 66 is read when original document moving reading is performed in which the image is read while the original document is being transferred by a document feeder, thereby acquiring shading data. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus that reads an image on a document, and more particularly to an image reading apparatus having a reference member for performing shading correction.

2. Description of the Related Art Conventionally, an image reading apparatus that automatically reads image information of a document is used as a reading apparatus such as a copying machine or a facsimile or a scanner for computer input. In this type of image reading apparatus, the original is irradiated with light using a light source extending in the main scanning direction, and the reflected light reflected from the irradiated original is read by the reading unit.
As a reading method in such a conventional image reading apparatus, a so-called platen scanning method (original fixed reading method) in which an original is placed on a platen glass and an image of the original is read while moving the reading unit while fixing the original. In addition, a so-called CVT (Constant Velocity Transport) method (document flow reading method) that reads an image of a document while moving the document while fixing a reading unit below the platen glass is known (see Patent Document 1). ). At present, an image reading apparatus that shares a reading unit and can read an image of a document by a platen scan method and a CVT method has been put into practical use.

Further, in this type of image reading apparatus, there may occur a situation in which the amount of light emitted from the light source varies depending on the position in the main scanning direction, or the amount of light of the light source varies with time. When such variations or fluctuations in the amount of light occur, for example, when a document on which a halftone image is uniformly formed is read, the output image signal is non-uniform with variations depending on the amount of light from the light source. End up.
Therefore, a white member (white reference member) extending in the main scanning direction is disposed opposite to the light irradiation direction of the light source, and the white reference member is irradiated with light from the light source, and reflected light reflected from the white reference member is reflected. A method of acquiring correction data (shading data) corresponding to an illuminance distribution in a direction orthogonal to the document conveyance direction read in advance by a reading unit is widely used (see, for example, Patent Document 2). Then, during actual document reading operation, image data obtained by reading the document is corrected by using shading data (shading correction) to remove unevenness caused by the illuminance distribution of the light source.

Japanese Patent Laying-Open No. 2001-223832 (second page, FIG. 2) JP 2001-313794 A (page 3-4, FIG. 3)

  By the way, in the case of the CVT method described above, since the reading unit is fixed to the lower side of the platen glass, if foreign matter adheres to the platen glass, black streaks in the sub-scanning direction are generated in the read image. As a result, the image quality of the read image is deteriorated. In order to prevent the occurrence of such a problem, it is conceivable to suppress adhesion of foreign matter to the platen glass by transporting the original in a state of being floated from the platen glass when reading an image of the original by the CVT method. It is done.

However, if the above-described measures are adopted, the distance between the light source and the original differs between the case of reading the original using the platen scan method and the case of reading the original using the CVT method. A difference occurs in the illuminance distribution. If there is a difference in illuminance distribution in this way and shading correction is performed using the same shading data, even if one can be corrected without any problems, the other can eliminate unevenness due to the difference in illuminance distribution. There was a risk of disappearing.
In particular, recently, an LED array in which a large number of LEDs (Light Emitting Diodes) are arranged side by side has been used as a light source. In the case of a light source in which a plurality of such point light sources are arranged, the illuminance distribution is Since it has a waved shape, the shape of the illuminance distribution varies greatly depending on the distance from the light source, and striped image unevenness occurs in the main scanning direction.

  The present invention has been made to solve such a technical problem, and an object of the present invention is to enable appropriate shading correction according to a difference in reading conditions.

  For this purpose, an image reading apparatus to which the present invention is applied includes a placing means for placing a document, a transporting means for transporting the document, a document placed on the placing means, and a means for transporting the document. A reading unit that reads an image of a document to be conveyed, a first reference member provided at a position corresponding to a document surface of the document placed on the placing unit, and a document surface of the document conveyed by the conveyance unit By reading the second reference member provided at the corresponding position and the first reference member or the second reference member, shading data for correcting image data obtained by reading the image of the document is acquired. And a shading data acquisition means.

  Here, the image processing apparatus may further include a shading correction unit that corrects the image data of the document read by the reading unit using the shading data acquired by the shading data acquisition unit. Further, the reading means may be characterized in that the original is irradiated with light from a light source including a plurality of point light sources, and reflected light from the original is received by a light receiving element. Further, the position corresponding to the document surface of the document placed on the placement unit and the position of the document surface of the document transported by the transport unit may be different in height. In addition, the first reference member and the second reference member may be attached to a side facing the light source through a transmission member that transmits light. Further, the conveying unit can move the document so as to pass through a position away from the upper surface of the transmissive member by a predetermined distance. Furthermore, the transmissive member may constitute a placing unit for placing the document.

  From another point of view, an image reading apparatus to which the present invention is applied includes a light source that irradiates light on a document and a reading unit that reads reflected light from the document irradiated by the light source, and a transmissive member. The original fixed reading for reading the image formed on the original placed on the original at the first reading position is executed, and the second reading different from the first reading position for the image formed on the conveyed original is performed. A document reading unit that reads at a position, a reference member for document fixed reading that is read using a reading unit at a position corresponding to the first reading position, and a position corresponding to the second reading position. And a reference member for reading a document flow that is read using a reading unit.

  Here, the document fixing reference member is disposed at substantially the same height as the document reading surface at the first reading position, and the document flow reading reference member is approximately the document reading surface at the second reading position. It can be characterized by being arranged at the same height. Further, the light source can be characterized by comprising an LED array configured by arranging a plurality of LEDs (Light Emitting Diodes).

  According to the present invention, it is possible to perform appropriate shading correction according to a difference in reading conditions.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described below in detail with reference to the accompanying drawings.
—Embodiment 1—
FIG. 1 is a diagram showing an image reading apparatus to which the present embodiment is applied. This image reading apparatus is large and includes a document feeding device 10 as a conveying unit that sequentially conveys a document from a stacked document bundle, a scanner device 70 that reads an image by scanning, and a processing device that processes a read image signal. It is roughly divided into 80.

  A document feeder 10 serving as a document transport unit includes a document tray 11 on which a bundle of documents composed of a plurality of documents is stacked, and a tray lifter 12 that raises and lowers the document tray 11. Further, a nudger roll 13 that conveys the original on the original tray 11 raised by the tray lifter 12, a feed roll 14 that conveys the original conveyed by the nudger roll 13 further downstream, and an original supplied by the nudger roll 13. Are provided with a retard roll 15. In the first conveyance path 31 where the original is first conveyed, a take-away roll 16 that conveys the originals that are being fed one by one to the downstream roll, and further conveys the original to the further downstream roll and creates a loop. The pre-registration roll 17 to be performed, the rotation is resumed at the timing after stopping once, the registration roll 18 for supplying the original while adjusting the registration to the original reading unit, the platen roll 19 for assisting the conveyance of the original being read, An out-roll 20 is provided for conveying the read original further downstream. The first conveyance path 31 as a conveyance path is provided with a baffle 41 that rotates around a fulcrum according to the loop state of the conveyed document. Further, a CIS (Contact Image Sensor) 50 is provided between the platen roll 19 and the out-roll 20.

  A second transport path 32 and a third transport path 33 are provided on the downstream side of the out-roll 20, a transport path switching gate 42 for switching between these transport paths, a discharge tray 40 for stacking documents that have been read, and a discharge tray A first discharge roll 21 that discharges the original document 40 is provided. In addition, an inverter roll 22 and an inverter pinch roll 23 that are provided in the fourth transport path 34 and the fourth transport path 34 for switching back the document that has passed through the third transport path 33 and actually switch back the document, The document switched back by the fourth transport path 34 is again guided to the first transport path 31 including the pre-registration roll 17 and the like, and the document switched back by the fourth transport path 34 is discharged to the discharge tray 40. The transport paths of the second discharge roll 24, the fifth transport path 35, and the sixth transport path 36 that are provided in the sixth transport path 36 and the sixth transport path 36 and transport the inverted document to the first discharge roll 21. An exit switching gate 43 for switching is provided.

  The nudger roll 13 is lifted up and held at the retracted position during standby, and descends to the nip position (original conveyance position) during conveyance of the document to convey the uppermost document on the document tray 11. The nudger roll 13 and the feed roll 14 convey a document by connecting a feed clutch (not shown). The pre-registration roll 17 makes a loop by abutting the leading end of the document against the stopped registration roll 18. In the registration roll 18, when the loop is created, the leading edge of the document bitten by the registration roll 18 is returned to the nip position. When this loop is formed, the baffle 41 opens around the fulcrum and functions so as not to disturb the document loop. Further, the take away roll 16 and the pre-registration roll 17 hold a loop during reading. By this loop formation, the read timing can be adjusted, and the skew associated with the document conveyance at the time of reading can be suppressed, and the alignment adjustment function can be enhanced. The stopped registration roll 18 starts rotating in accordance with the start timing of reading, and is pressed against the second platen glass 72B (described later) by the platen roll 19 to read image data from the lower surface direction.

  The conveyance path switching gate 42 switches so that the document passing through the out-roll 20 is guided to the second conveyance path 32 and discharged to the discharge tray 40 at the end of reading one-sided document and at the same time when reading both-side documents simultaneously. It is done. On the other hand, the transport path switching gate 42 is switched so as to guide the document to the third transport path 33 in order to invert the document when the double-sided document is sequentially read. The inverter pinch roll 23 is retracted with the feed clutch (not shown) turned off during sequential reading of the double-sided document to open the nip, and guides the document to the inverter path (fourth conveyance path 34). Thereafter, the inverter pinch roll 23 is nipped, the original to be inverted by the inverter roll 22 is guided to the pre-registration roll 17, and the original to be reversed is conveyed to the second discharge roll 24 in the sixth conveyance path 36.

  The scanner device 70 can include the document feeding device 10 described above, supports the document feeding device 10 with a device frame 71, and reads an image of a document conveyed by the document feeding device 10. In the scanner device 70, a document that is being conveyed by the document feeding device 10, a first platen glass 72 A serving as a placing unit or a transmissive member that places a document to be read in a stationary state on the device frame 71. A second platen glass 72B that forms an opening for reading light is provided. In the present embodiment, the document feeder 10 is attached to the scanner device 70 so as to be swingable with the back side as a fulcrum, and when the document is set on the first platen glass 72A, the document is The document feeder 10 is lifted to place a document, and then the document feeder 10 is lowered to the scanner device 70 and pressed. In the present embodiment, the first platen glass 72A and the second platen glass 72B are provided as separate solid bodies, but they can be configured as an integral platen glass.

  In addition, the scanner device 70 is stationary under the second platen glass 72B and scans the entire first platen glass 72A to read the image, and the light obtained from the full rate carriage 73 is read. A half-rate carriage 75 is provided to the image coupling unit. The full-rate carriage 73 is provided with a white LED (Light Emitting Diode) array 74 as a light source for irradiating light on the document, and a first mirror 76A for receiving reflected light obtained from the document. Further, the half-rate carriage 75 is provided with a second mirror 76B and a third mirror 76C that provide the light obtained from the first mirror 76A to the imaging unit. Further, the scanner device 70 includes an imaging lens 77 that optically reduces the optical image obtained from the third mirror 76C, and a CCD as a light receiving element that photoelectrically converts the optical image formed by the imaging lens 77. (Charge Coupled Device) An image sensor 78 and a drive substrate 79 including a CCD image sensor 78 are provided, and an image signal obtained by the CCD image sensor 78 is sent to the processing device 80 via the drive substrate 79. These full-rate carriage 73, white LED array 74, half-rate carriage 75, first mirror 76A, second mirror 76B, third mirror 76C, imaging lens 77, and CCD image sensor 78 constitute a reading means (reading unit). The full rate carriage 73, the half rate carriage 75, the first mirror 76A, the second mirror 76B, the third mirror 76C, the imaging lens 77, and the CCD image sensor 78 constitute a reading unit. The configuration of the white LED array 74 will be described later.

  In the case of fixed document reading for reading an image of a document placed on the first platen glass 72A, the full rate carriage 73 and the half rate carriage 75 move in the scanning direction (arrow direction) at a ratio of 2: 1. . At this time, the light from the white LED array 74 of the full-rate carriage 73 is irradiated onto the surface to be read of the document, and the reflected light from the document is in order of the first mirror 76A, the second mirror 76B, and the third mirror 76C. The light is reflected and guided to the imaging lens 77. The light guided to the imaging lens 77 forms an image on the light receiving surface of the CCD image sensor 78. The CCD image sensor 78 is a one-dimensional sensor and processes one line at the same time. When reading of one line in this line direction (main scanning direction of scanning) is completed, the full-rate carriage 73 is moved in a direction (sub-scanning direction) orthogonal to the main scanning direction to read the next line of the document. By executing this over the entire document size, reading of one page of the document is completed.

  On the other hand, the second platen glass 72B is constituted by a transparent glass plate having a long plate-like structure, for example. Here, the second platen glass 72B is made of the same material and the same thickness as the first platen glass 72A. In the case of document flow reading for reading an image of a document passing over the second platen glass 72B, the document conveyed by the document feeder 10 passes over the second platen glass 72B. At this time, the full-rate carriage 73 and the half-rate carriage 75 are stopped at the solid line positions shown in FIG. First, the reflected light of the first line of the document irradiated by the white LED array 74 and passed through the platen roll 19 of the document feeder 10 passes through the first mirror 76A, the second mirror 76B, and the third mirror 76C, and the imaging lens. The image is formed at 77 and an image is read by the CCD image sensor 78 which is the first sensor in the present embodiment. That is, after one line in the main scanning direction is simultaneously processed by the CCD image sensor 78 which is a one-dimensional sensor, the next line in the main scanning direction of the original conveyed by the original feeding device 10 is read. After the leading edge of the document reaches the reading position of the second platen glass 72B, the document passes through the reading position of the second platen glass 72B, thereby completing the reading of one page in the sub-scanning direction.

  In the present embodiment, the full-rate carriage 73 and the half-rate carriage 75 are stopped and the second platen glass 72B reads the first surface of the document by the CCD image sensor 78 at the same time (when the time is passed). It is possible to read the second side of the document by the CIS 50 (meaning that it is not completely coincident but the same as when the same document is conveyed). That is, by using the CCD image sensor 78 and the CIS 50, it is possible to read the images on both the front and back sides of the original by one conveyance of the original to the conveyance path.

  FIG. 2 is a diagram for explaining the structure of the CIS 50 and the vicinity of the CIS 50. As shown in FIG. 2, the CIS 50 is provided between the platen roll 19 and the out roll 20. In the present embodiment, the jump base 44 is attached to the upper surface of the second platen glass 72B and slightly upstream from the platen roll 19. One side (first side) of the document passes through the jump table 44 and is urged toward the second platen glass 72B by the platen roll 19 while being separated from the second platen glass 72B by a predetermined distance. One image is read by the CCD image sensor 78. On the other hand, in the CIS 50, an image on one side (second side) is read from the other side facing through a conveyance path for conveying a document.

  The CIS 50 includes a housing 50 a, a glass 51 mounted on the housing 50 a, an LED array 52 that transmits light through the glass 51 and irradiates the second surface of the document, and collects reflected light from the LED array 52. A self-focusing lens (registered trademark) 53 that emits light and a line sensor 54 that reads the light collected by the self-focusing lens 53 are provided. As the line sensor 54, a CCD, a CMOS sensor, a contact sensor, or the like can be used, and an image with an actual width (for example, A4 longitudinal width 297 mm) can be read. In the CIS 50, since the image is captured using the SELFOC lens 53 and the line sensor 54 without using the reduction optical system, the structure can be simplified, the housing can be downsized, and the power consumption can be reduced. Can be reduced.

  In addition, when the image is read by the CIS 50, a control member 55 extending from the casing of the CIS 50 and an abutting member 60 that abuts the original pressed by the control member 55 are provided in the conveyance path constituting the reading unit. However, while the control member 55 is attached to the document feeder 10 (see FIG. 1) via the CIS 50, the abutting member 60 is attached to the scanner device 70 (see FIG. 1). Further, a guide member 61 is provided on the downstream side of the abutting member 60, and an opening 63 is formed between the guide member 61 and the abutting member 60. In a portion continuous with the opening 63, a dust storage portion 62 is provided as a collection portion for collecting dust and dirt adhering to the surface of the document. The control member 55 and the abutting member 60 correspond to the positions of the conveyance path from the front surface to the rear surface of the document feeder 10 in a direction perpendicular to the document conveyance path (that is, from the front surface to the rear surface of the document feeder). Is provided.

Here, the control member 55 is configured by a leaf spring made of a U-shaped sheet metal wound around a shaft 55a provided in the CIS 50, and is conveyed by making the control member 55 flexible. The thickness of the incoming document can be absorbed, and even a document with a bent trace can be stably conveyed.
Further, the front end side of the control member 55 extends to the vicinity of a reading position by the CIS 50, and a hemming bent portion 55b is provided at a portion that comes into contact with the original, and it comes into contact with the original and the smooth to generate paper dust or the like. Can be prevented. The distance between the folding portion 55b of the control member 55 and the abutting member 60 (gap for passing the document) is set to about 0.1 to 1.0 mm.

  On the other hand, the abutting member 60 is provided on the upstream side in the document conveyance direction, and a conveyance surface 60a for guiding the document to be conveyed, and one level lower than the conveyance surface 60a on the downstream side in the document conveyance direction from the conveyance surface 60a. And a step surface 60b formed. Further, the step surface 60b is formed so as to face the extension line of the light focus point by the SELFOC lens 53, and a white reference tape 64 made of a biaxially stretched polyester film is pasted on the step surface 60b. It is attached. Therefore, the white reference tape 64 is attached to the scanner device 70 via the abutting member 60. In the present embodiment, the upper surface of the white reference tape 64 is arranged in a state of being exposed to the conveyance path.

  Here, since the CIS 50 employs the SELFOC lens 53 as the optical imaging lens, the focal point (field of view) seismic intensity is as shallow as about ± 0.3 mm, which is approximately the same as when the scanner device 70 is used. The depth is 1/13 or less. When reading with the CIS 50, it is required to keep the reading position of the document within a predetermined narrow range. Therefore, in the present embodiment, the control member 55 is provided, and the document is pressed against the abutting member 60 by the control member 55 and conveyed, so that the posture of the document between the platen roll 19 and the out-roll 20 can be stabilized. Configured to be controllable. 2 indicates the movement of the document when the control member 55 is provided. It is understood that the document to be conveyed is conveyed while being pressed against the abutting member 60. That is, the control member 55 reads the conveyed document while being pressed against the abutting member 60, thereby improving the sweetness of the focus when the CIS 50 having a shallow depth of field is used.

  In addition, a first white reference member (first reference member) attached to the lower side of the abutting member 60 and in close contact with the first platen glass 72A on the upper side of the first platen glass 72A. A first white reference plate 65 as a member, a reference member for reading and fixing a document), and a second white reference member (a second white reference member) attached so as to be separated from the first platen glass 72A with a predetermined space a. A second white reference plate 66 is provided as a reference member and a reference member for document flow reading). The details of the first white reference plate 65 and the second white reference plate 66 will be described later.

Next, the processing device 80 shown in FIG. 1 will be described.
FIG. 3 is a block diagram for explaining the processing device 80. The processing device 80 to which this embodiment is applied is large and controls the signal processing unit 81 that processes image information obtained from the sensors (CCD image sensor 78 and CIS 50), the document feeder 10 and the scanner device 70. And a control unit 90. The signal processing unit 81 performs predetermined image processing on outputs from the CCD image sensor 78 that reads the front surface (first surface) of the document and the line sensor 54 of the CIS 50 that reads the back surface (second surface). . The signal processing unit 81 includes an AFE (Analog Front End) 82 that processes an analog signal with respect to an output from the line sensor 54, and an ADC (Analog to Digital Converter) 83 that converts the analog signal into a digital signal. Yes. However, these functions may be configured to be processed inside the CIS 50. The signal processing unit 81 includes two systems of image processing circuits that perform various processing such as shading correction and offset correction on the digital signal, and performs image processing on the image data on the front surface (first surface). A first image processing circuit 100 for performing image processing and a second image processing circuit 200 for performing image processing on image data on the back surface (second surface) are provided. Outputs from these image processing circuits are output to a host system such as an IOT (Image Output Terminal) such as a printer or a personal computer (PC).

  On the other hand, the control unit 90 includes an image reading control 91 that controls the entire document feeding device 10 and the scanner device 70, including various double-sided scanning control and single-sided scanning control, a CCD image sensor 78 that is a first sensor, and A CCD / CIS control 92 for controlling the CIS 50, a lamp control 93 for controlling the LED array 52 of the CIS 50 and the white LED array 74 of the full-rate carriage 73 in accordance with the read timing, a full-rate carriage by turning on / off the motor in the scanner device 70, etc. 73, a scanning control 94 for controlling the scanning operation of the half-rate carriage 75, a motor for controlling the motor in the document feeding device 10, various roll operations, a feed clutch operation, a gate switching operation, and the like. It is provided with a control 95. From these various controls, control signals are output to the document feeder 10 and the scanner device 70, and these operations can be controlled based on the control signals. The image reading control 91 sets a reading mode based on a control signal from the host system, a sensor output detected in the automatic selection reading function, a selection from the user, and the like, and controls the document feeder 10 and the scanner device 70. I have control. Examples of such a reading mode include a double-sided simultaneous reading mode using one pass (no reversal), a reversing double-sided reading mode using a reversing pass, a single-sided reading mode using one pass, and the like, or the first platen glass 72A It is conceivable to perform fixed document reading by placing a document on the top and reading it.

Next, the function and operation of each image processing circuit (first image processing circuit 100 and second image processing circuit 200) will be described.
FIG. 4 is a block diagram illustrating the configuration of the signal processing unit 81 in further detail. The first image processing circuit 100 includes a first CPU 101 that performs overall control, an AFE 102 that performs sample hold, offset adjustment, A / D conversion, and the like on the surface image data output from the CCD image sensor 78, and front and back images. A selector (SEL) 103 for selecting and outputting data is provided. Furthermore, an A integrated circuit (ASIC-A) 110 that executes shading correction, line interpolation (RGB misregistration interpolation), and the like, and an B integrated circuit (ASIC-B) that executes MTF filter, reduction / enlargement processing, binarization processing, etc. ) 130.

  On the other hand, the second image processing circuit 200 is obtained from a second CPU 201 that performs overall control, for example, white reference shading data at the time of factory shipment, a flash ROM (FROM) 202 that stores (stores) LED light amount correction values, and a CIS 50. C integrated circuit (ASIC-C) 210 that performs various image processing on the backside image data, and temporarily holds the backside image data that has undergone image processing, and outputs it to the selector 103 in accordance with a predetermined output timing The memory 203 is provided. In the present embodiment, white reference shading data obtained in advance at the time of factory shipment is stored in a flash ROM (FROM) 202 by the CIS 50 which is a contact image sensor for reading the back surface.

FIG. 5 is a block diagram showing the configuration of the A integrated circuit (ASIC-A) 110. The A integrated circuit 110 includes a shading correction unit 111 for correcting shading data in the CCD image sensor 78, a GAP correction unit 112 for correcting the positions of RGB line sensors, a black line correction unit 113 for correcting black lines, and an input. An ENL 115 that performs side gradation correction and a color space conversion unit 116 that converts BGR → L ^* , a ^* , b ^* are provided. Further, a timing generation unit 119 that generates drive clocks for the CCD image sensor 78 and the AFE 102, a CPU interface 120 that communicates with the first CPU 101, and a shading memory 121 that stores shading data used by the shading correction unit 111 are provided.

FIG. 6 is a block diagram showing the configuration of the B integrated circuit (ASIC-B) 130. The B integrated circuit 130 includes a digital filter unit 131 that performs MTF correction and smoothing, a sub-scanning reduction unit 132 that performs a reduction process with respect to the sub-scanning direction that is the document transport direction, and a CCD that is in a direction orthogonal to the document transport direction. A main scanning enlargement / reduction unit 133 that performs enlargement / reduction processing in the main scanning direction that is the scanning direction of the image sensor 78, a background removal unit 135 that removes the background of the read document, L ^* , a ^* , b ^* → Y, M, C , K is provided with a look-up table (LUT) 136 for color space conversion. Further, a background detection unit 139 that detects the background of the read document and a CPU interface 140 that communicates with the first CPU 101 are provided.

FIG. 7 is a block diagram showing the configuration of the C integrated circuit (ASIC-C) 210. The C integrated circuit 210 includes a multiplex (MPX O / E synthesis) circuit 211 that synthesizes output signals of two channels composed of Odd / Evn, and a shading correction unit that performs shading correction based on data stored in the shading memory 221. 212, an L ^* conversion (LUT) unit 213 that performs input tone correction, a sub-scanning / reduction unit 214 that performs a reduction process in the sub-scanning direction, a main-scan enlargement / reduction unit 215 that performs an enlargement / reduction process in the main-scanning direction, A filter unit 216 that performs MTF correction and smoothing, a background removal unit 217 that performs background removal based on a background detection result by the background detection unit 222, a lookup table (LUT) 218 that performs output tone correction, and binarization. An error diffusion (packing error diffusion) unit 219 is provided. In addition, a CPU interface 223 that performs communication with the second CPU 201 is provided.

  FIG. 8 is a flowchart showing an example of processing executed by the image reading control 91 shown in FIG. In the image reading control 91, first, it is determined whether the original is fixedly read or the original is read (step 101). This determination is made by, for example, selection from a user using a control panel (not shown) provided on the scanner device 70, or, for example, when the automatic selection reading function is working, the first conveyance before image reading. It can be recognized by sensors (not shown) provided on both sides of the conveyance path on the path 31 or sensors (not shown) provided below the first platen glass 72A. In addition, a request from the host system or a selection from the user via a network or the like can be considered. If it is determined in step 101 that the original is fixed, reading is performed on one side by fixing the original (the original is placed and fixed on the first platen glass 72A) (step 102). In the single-sided reading by fixing the original, reading by the CCD image sensor 78 is performed.

  On the other hand, if it is determined in step 101 that the document flow is read, it is next determined whether or not the conveyed document, that is, the document placed on the document tray 11 is a single-sided document (step 103). This determination is made by, for example, selection from a user using a control panel (not shown) provided on the scanner device 70, or, for example, when the automatic selection reading function is working, the first conveyance before image reading. It can be recognized by sensors (not shown) provided on both sides of the conveyance path on the path 31. In addition, a request from the host system or a selection from the user via a network or the like can be considered. If it is determined in step 103 that the original is a single-sided original, single-sided reading is performed by one pass (one-time original conveyance pass without using a reverse pass) (step 104). In this one-pass single-sided reading, either the reading by the CCD image sensor 78 or the reading by the CIS 50 may be selected. However, in order to realize higher-quality image reading, the reading by the CCD image sensor 78 is selected. It is preferable to do. In such a case, the document tray 11 is placed so that there is a single-sided document portion facing upward and the first page of the document comes up, and the document is transported from the first page and sequentially read.

  Here, if it is not a single-sided original in step 103, that is, if it is a double-sided original, it is determined whether or not the original is a white / black original (step 105). The determination in step 105 is determined by the selection from the user or the automatic selection reading function as in step 103. There are cases where the user desires white / black reading even for a color original. When white / black reading is not performed, that is, when color reading is performed, it is next determined whether or not the image quality is important (step 106). For example, in the case of a color image such as a color photograph or a pamphlet, image quality is generally more important than productivity for increasing the reading speed. Such a determination is also made based on user settings. If it is determined in step 106 that the image quality is important, double-sided reading is executed by the reverse pass (step 107). That is, the CCD image sensor 78 reads both the first side of the original and the second side of the original without reading by the CIS 50. As a result, both the first side of the original and the second side of the original can be read on both sides with high image quality using the reading means having a deep focal depth.

  On the other hand, when white / black reading is performed in step 105 or when a color image output is required in step 106, for example, when subtle hues such as business colors are not emphasized, plus one color In the case of (including other one color such as red or blue in addition to black), if the image quality is not very important and other factors such as productivity are important, the reverse path is not used. Simultaneous reading on both sides by one pass is performed (step 108). That is, the first surface is read by the CCD image sensor 78, and the second surface is read by the CIS 50 in the same transport path during this transport path. As a result, it is not necessary to transport the document twice to the same reading unit, the document reading speed can be improved, and the transport path is simplified, so that document transportation troubles such as document jamming (JAM) can be prevented. Can be suppressed. As described above, “simultaneous reading” does not necessarily mean a case where they coincide with each other in time, but means that both sides are read almost simultaneously in one pass.

  Note that the processing flow shown in FIG. 8 is simplified, and when reading a black and white original in double-sided original reading, double-sided simultaneous reading in step 108 is executed, and in the case of a color original, the reverse path in step 107 is sequentially performed. It is also possible to configure to read a document. Also, these modes can be mixed and used according to the type of document surface.

  Here, when the single-sided reading mode by original fixing shown in step 102 of FIG. 8 is selected, the image of the original placed on the first platen glass 72A is converted into the full-rate carriage 73 and Reading is performed while moving the half-rate carriage 75.

Next, a method for conveying a document in each document reading mode for document flow reading will be described with reference to FIGS.
FIGS. 9A and 9B show the document path in the single-sided reading mode by one pass shown in step 104 of FIG. 8 and the second double-sided reading mode in which double-sided simultaneous reading by one pass shown in step 108 is performed. FIG. As shown in FIG. 9A, the documents placed on the document tray 11 are sequentially supplied to the first conveyance path 31 by the nudger roll 13, the feed roll 14, the retard roll 15, and the takeaway roll 16. The As shown in FIG. 9B, the supplied document is moved to the second conveyance path 32 by the conveyance path switching gate 42 via the reading section of the platen roll 19 and the reading section of the CIS 50, and the discharge tray 40. Are sequentially discharged. In the case of single-sided reading, reading is performed using the CCD image sensor 78 of the scanner device 70 shown in FIG. However, as described above, single-sided reading using the CIS 50 is also possible. In the case of simultaneous reading on both sides by one pass, the first surface is read using the CCD image sensor 78 of the scanner device 70, and the second surface is read using the CIS 50 during the same conveyance. As a result, it is possible to read both sides of the document by one document pass.

  FIGS. 10A to 10D are diagrams for explaining the double-sided reading by the reverse path shown in step 107 of FIG. 8, that is, the first double-sided reading mode. As shown in FIG. 10A, the originals placed on the original tray 11 are sequentially supplied to the first transport path 31, and the platen roll is used by using the CCD image sensor 78 of the scanner device 70 shown in FIG. Reading is performed from below at 19 locations. Then, the transfer path switching gate 42 moves to the fourth transfer path 34 via the third transfer path 33. The document completely passing through the third conveyance path 33 is switched back by the inverter roll 22 and the inverter pinch roll 23 and supplied to the fifth conveyance path 35 as shown in FIG.

  The document supplied to the fifth conveyance path 35 is again supplied to the first conveyance path 31. Then, as shown in FIG. 10 (c), the document is read from below by the CCD image sensor 78 of the scanner device 70. At this time, the document is in an inverted state from the case shown in FIG. 10A, and the second side that is different from the first side is read. The original on which the second side has been read is in an inverted state. If the original is discharged to the discharge tray 40 as it is, the page order of the loaded original after reading will be out of order. Therefore, as shown in FIG. 10C, the document whose second surface has been read is moved to the fourth transport path 34 via the third transport path 33 using the transport path switching gate 42. The document supplied to the fourth conveyance path 34 and completely passing through the exit switching gate 43 is discharged to the discharge tray 40 by the outlet switching gate 43 via the sixth conveyance path 36 as shown in FIG. Is done. This makes it possible to align the page order of the original after reading in the first double-sided reading mode in which images on both sides of the original are sequentially read.

  In this image reading apparatus, at the time of executing the document flow reading, the CCD image sensor 78 is used to read one side (first surface) of the document, and then the document is reversed and the other side (second surface) is placed on the CCD. Using the first double-sided reading mode in which the image sensor 78 sequentially reads, and the CCD image sensor 78 and the CIS 50 provided on the other side facing the CCD image sensor 78 through the conveyance path, the original is read once. A second double-sided reading mode for reading both front and back surfaces (first surface and second surface) by conveyance was prepared. These modes are configured to be selectable automatically as necessary or based on user designation or the like. This makes it possible to select the duplex scanning mode appropriately and use these modes depending on the application, for example, whether output is monochrome or color, whether speed (productivity) is important, or whether image quality is important. It is possible to do. In the present embodiment, the second platen glass is provided by providing the first platen glass 72A and disposing the full rate carriage 73 and the half rate carriage 75 constituting the scanner device 70 so as to be movable in the main scanning direction. In addition to being able to read and scan an original image conveyed on 72B, the original image placed on the first platen glass 72A can be fixedly read.

In this image reading apparatus, the shading data used for shading correction is acquired in each of the CIS 50 and the scanner device 70 before the image reading job for the original in each of the above-described original reading modes is started.
First, the shading data acquisition operation on the CIS 50 side will be described. Here, the CIS 50 is used only at the time of document flow reading. In the CIS 50, before starting the document reading operation, first, the LED array 52 is turned on, and the reflected light from the white reference tape 64 is acquired as reflected data via the SELFOC lens 53 and the line sensor 54. Next, shading data is generated in the processing device 80 based on the acquired reflection data from the white reference tape 64, and the generated shading data is stored in the shading memory 221 provided in the C integrated circuit 210. Then, during actual document reading operation, the image data obtained by reading the document with the CIS 50 is corrected by the shading correction unit 212 using the shading data stored in the shading memory 221, and the light amount distribution of the LED array 52 is obtained. After removing the unevenness, output to the host system. This shading data acquisition can be set at an appropriate timing, for example, before the start of a job or for each sheet on which an image is read.

  Next, acquisition of shading data on the scanner device 70 side will be described. Here, in the present embodiment, the scanner device 70 is used for both the document fixed reading and the document flow reading, and shading data is acquired in both the document fixed reading and the document flow reading. The white reference plate is different.

  When performing original fixed reading, that is, when reading an image of an original placed on the first platen glass 72A, first, the first mirror 76A is moved to the first mirror 76A before starting the original reading operation. The full rate carriage 73 and the half rate carriage 75 are moved to a position α (a position corresponding to the first reading position) located below the white reference plate 65. Next, the white LED array 74 provided on the full rate carriage 73 is turned on to reflect the reflected light from the first white reference plate 65 to the first mirror 76A, the second mirror 76B, the third mirror 76C, and the imaging lens 77. Then, it is obtained as reflection data via the CCD image sensor 78. Next, based on the acquired reflection data from the first white reference plate 65, shading data is generated in the processing device 80 as a shading data acquisition unit, and the generated shading data is shaded provided in the A integrated circuit 110. Store in the memory 121. During the actual document reading operation, the full-rate carriage 73 and the half-rate carriage 75 are moved to a position β (first reading position) where the first mirror 76A is located at the lower end of the document (not shown). The image is read while moving the full rate carriage 73 and the half rate carriage 75. Then, the image data obtained by reading the document with the scanner device 70 (CCD image sensor 78) is corrected by using the shading data stored in the shading memory 121 in the shading correction unit 111 serving as a shading correction unit, and white. After removing the unevenness caused by the light quantity distribution of the LED array 74, it is output to the host system.

  On the other hand, when performing document flow reading, that is, when reading an image of a document passing over the second platen glass 72B, first, the first mirror 76A is set to the second mirror before starting the document reading operation. The full rate carriage 73 and the half rate carriage 75 are moved to a position γ (a position corresponding to the second reading position) located below the white reference plate 66. Next, the white LED array 74 provided on the full rate carriage 73 is turned on to reflect the reflected light from the second white reference plate 66 to the first mirror 76A, the second mirror 76B, the third mirror 76C, and the imaging lens 77. Then, it is obtained as reflection data via the CCD image sensor 78. Next, shading data is generated in the processing device 80 based on the acquired reflection data from the second white reference plate 66, and the generated shading data is stored in the shading memory 121 provided in the A integrated circuit 110. During the actual document reading operation, the full-rate carriage 73 and the half-rate carriage 75 are moved to a position δ (second reading position) where the first mirror 76A is positioned at the lower end of the document (not shown). The image is read while the full rate carriage 73 and the half rate carriage 75 are stationary. Then, the image data obtained by reading the document with the scanner device 70 (CCD image sensor 78) is corrected by the shading correction unit 111 using the shading data stored in the shading memory 121, and the light quantity of the white LED array 74 is corrected. After removing unevenness due to distribution, the data is output to the host system.

Next, the reason why the white reference plate used for acquiring shading data on the scanner device 70 side is different between the case of original fixed reading and the case of original flow reading will be described.
FIG. 11 is a diagram showing the relationship between the reading height of the document and the mounting heights of the first white reference plate 65 and the second white reference plate 66 in document fixed reading and document flow reading. In the present embodiment, the height of the upper surface of the first platen glass 72A used for original fixed reading and the height of the upper surface of the second platen glass 72B used for original flow reading are the first height. It is set to H1. When the original is fixedly read, the original is placed on the first platen glass 72A. In this case, the height of the original surface is the first height H1. On the other hand, at the time of document flow reading, the document is jumped by the jump table 44 attached to the second platen glass 72B and is conveyed while being lifted from the second platen glass 72B. This is the second height H2.

  Here, FIG. 12 is a diagram showing an example of the configuration of the white LED array 74 provided on the scanner device 70 side and its illuminance distribution. The white LED array 74 is configured by arranging a large number of white LEDs 74b as point light sources in parallel on an LED substrate 74a extending in the main scanning direction. In addition, what is shown by the elliptical shape in the same figure is a site | part from which the illumination intensity from each white LED 74b becomes the same. Since each of these white LEDs 74b is a point light source, the illuminance distribution as a whole of the white LED array 74 is a combination of the illuminance distributions of the individual white LEDs 74b, and is generally wavy. The size of the undulation in the illuminance distribution varies depending on the distance from the white LED array 74. For this reason, as shown in the figure, the illuminance distribution at the first height H1 and the illuminance distribution at the second height H2 have different profiles.

  Therefore, in the present embodiment, as shown in FIG. 11, the white reference surface 65a of the first white reference plate 65 is made to coincide with the position of the original surface at the time of original fixed reading, that is, the first height H1, and The first white reference plate 65 and the second white reference plate 66 are arranged so that the white reference surface 66a of the second white reference plate 66 coincides with the position of the document surface at the time of document flow reading, that is, the second height H2. It is attached. Then, the shading data is obtained by reading the first white reference plate 65 when performing the fixed document reading and reading the second white reference plate 66 when performing the document flow reading. As a result, shading data can be acquired under the same conditions as the reading conditions for original fixed reading or original flow reading. By applying shading correction using the obtained shading data, a white LED that is an aggregate of point light sources is obtained. Unevenness caused by the difference in illuminance distribution caused by using the array 74 can be suppressed. That is, it is possible to perform appropriate shading correction according to the difference in reading conditions. Here, in the present embodiment, the second white reference plate 66 is mounted on the first platen glass 72A side, but the first platen glass 72A and the second platen glass 72B are made of the same material and have the same thickness. For this reason, it is possible to make the reading conditions substantially the same when reading the original by reading the original and when reading the second white reference plate 66, and no particular problem occurs.

  In the present embodiment, since the first white reference plate 65 and the second white reference plate 66 are attached to the side facing the white LED array 74 through the first platen glass 72A, dust or the like is attached. There is no possibility of adhering directly to the white reference surface 65a of the first white reference plate 65 or the white reference surface 66a of the second white reference plate 66. Furthermore, in the present embodiment, since the first white reference plate 65 and the second white reference plate 66 are attached to the abutting member 60 disposed to face the CIS 50, the apparatus can be made compact. Furthermore, in this embodiment, since the first white reference plate 65 is provided for reading a fixed original and the second white reference plate 66 is provided for reading a document, each of the white LED array 74 is configured. Therefore, it is not necessary to consider the profile of the illuminance distribution caused by the intensity of light emission intensity of the white LED 74b, the arrangement interval, etc., and the optical design of the apparatus becomes easy.

-Embodiment 2-
The present embodiment is substantially the same as the first embodiment, but the second white reference plate 66 is arranged not on the first platen glass 72A but on the second platen glass 72B. Is. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
FIG. 13 is a diagram for explaining the structure of the CIS 50 and the vicinity of the CIS 50. In the present embodiment, the jump table 44 attached to the upper surface of the second platen glass 72B and slightly upstream from the platen roll 19 has a structure having a curved document guide surface. A second white reference plate 66 that is attached so as to be separated from the second platen glass 72 </ b> B with a predetermined space a is attached to the lower part. It is to be noted that the white reference surface 66a, which is the lower surface of the second white reference plate 66, is set to the same height as the document surface at the time of document flow reading, as in the first embodiment.

  Also in the present embodiment, shading data is acquired by reading the first white reference plate 65 when performing fixed document reading and by reading the second white reference plate 66 when performing document flow reading. As a result, shading data can be acquired under the same conditions as the reading conditions for original fixed reading or original flow reading. By applying shading correction using the obtained shading data, a white LED that is an aggregate of point light sources is obtained. It is possible to suppress unevenness caused by the difference in illuminance distribution caused by using the array 74. In particular, in the present embodiment, since the second white reference plate 66 is provided on the second platen glass 72B side, the second white reference plate 66 is read under exactly the same conditions as the reading conditions in document flow reading. Thus, shading data for reading a document flow can be acquired, and more accurate shading correction can be performed. Therefore, in this case, the materials and thicknesses of the first platen glass 72A and the second platen glass 72B can be made different according to the required specifications and performance.

It is the figure which showed the image reading apparatus with which this Embodiment is applied. It is a figure for demonstrating the structure of CIS and the CIS vicinity. It is a block diagram for demonstrating a processing apparatus. It is the block diagram which detailed the structure of the signal processing part. It is the block diagram which showed the structure of A integrated circuit (ASIC-A). It is the block diagram which showed the structure of B integrated circuit (ASIC-B). It is the block diagram which showed the structure of C integrated circuit (ASIC-C). It is the flowchart which showed an example of the process performed by image reading control. (a), (b) is a figure for demonstrating the original path | pass of the 2nd double-sided reading mode which is the single-sided reading mode by 1 pass, and the double-sided simultaneous reading by 1 pass. (a)-(d) is a figure for demonstrating the double-sided reading by an inversion path | pass. It is a figure which shows the relationship between the reading height of an original in original fixed reading and original flow reading, and the attachment height of a 1st white reference board and a 2nd white reference board. It is a figure which shows an example of a structure of the white LED array provided in a scanner apparatus side, and its illuminance distribution. FIG. 10 is a diagram for explaining a structure in the vicinity of CIS and CIS in the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Document feeder, 11 ... Document tray, 19 ... Platen roll, 20 ... Out roll, 31 ... 1st conveyance path, 32 ... 2nd conveyance path, 33 ... 3rd conveyance path, 34 ... 4th conveyance path, 35 ... 5th transport path, 36 ... 6th transport path, 40 ... Discharge tray, 50 ... CIS (Contact Image Sensor), 51 ... Glass, 52 ... LED (Light Emitting Diode) array, 53 ... Selfoc lens, 54 ... Line Sensor, 55 ... Control member, 60 ... Abutting member, 61 ... Guide member, 62 ... Dust storage part, 63 ... Opening part, 64 ... White reference tape, 70 ... Scanner device, 71 ... Device frame, 72A ... First Platen glass, 72B ... second platen glass, 73 ... full-rate carriage, 74 ... white LED array, 74a ... LED substrate, 74b ... white LED, 75 ... half-rate carriage, 76A ... DESCRIPTION OF SYMBOLS 1 mirror, 76B ... 2nd mirror, 76C ... 3rd mirror, 77 ... Imaging lens, 78 ... CCD image sensor, 80 ... Processing apparatus, 81 ... Signal processing part, 90 ... Control part, 100 ... 1st image processing Circuits 110 ... A integrated circuit (ASIC-A) 111 ... Shading correction unit 130 ... B integrated circuit (ASIC-B) 200 ... Second image processing circuit 210 ... C integrated circuit (ASIC-C) 212 ... Shading correction unit, 221 ... Shading memory

Claims (10)

A placing means for placing a document;
Conveying means for conveying an original;
A reading unit that reads a document placed on the placing unit and reads an image of the document conveyed by the conveying unit;
A first reference member provided at a position corresponding to the document surface of the document placed on the placing means;
A second reference member provided at a position corresponding to the original surface of the original conveyed by the conveying means;
Shading data acquisition means for acquiring shading data for correcting image data obtained by reading an image of a document by reading the first reference member or the second reference member. Image reading device.   The image reading apparatus according to claim 1, further comprising a shading correction unit that corrects image data of the original read by the reading unit using the shading data acquired by the shading data acquisition unit. .   The image reading apparatus according to claim 1, wherein the reading unit irradiates the original with light from a light source including a plurality of point light sources, and receives light reflected from the original with a light receiving element.   2. The image according to claim 1, wherein the height of the position corresponding to the document surface of the document placed on the placing means differs from the position of the document surface of the document transported by the transport means. Reader.   The image reading apparatus according to claim 1, wherein the first reference member and the second reference member are attached to a side facing the light source through a transmission member that transmits light.   The image reading apparatus according to claim 5, wherein the transport unit moves the document so as to pass a position separated from the upper surface of the transmission member by a predetermined distance.   6. The image reading apparatus according to claim 5, wherein the transmissive member constitutes a placement unit for placing a document. A first reading position having a light source for irradiating light on the original and a reading unit for reading reflected light from the original irradiated by the light source, and an image formed on the original placed on the transmissive member A document reading unit for performing document fixing reading, and performing document flow reading for reading an image formed on the conveyed document at a second reading position different from the first reading position;
A document fixing reference member that is read using the reading unit at a position corresponding to the first reading position;
An image reading apparatus including a reference member for reading a document flow that is read using the reading unit at a position corresponding to the second reading position.   The document fixing reference member is disposed at substantially the same height as the document reading surface at the first reading position, and the document flow reading reference member is disposed at the second reading position with the document reading surface. The image reading apparatus according to claim 8, wherein the image reading apparatuses are arranged at substantially the same height.   The image reading apparatus according to claim 8, wherein the light source includes an LED array configured by arranging a plurality of LEDs (Light Emitting Diodes).

Images