JP2006014093A - Image reading device and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce blots in read-out image, caused by light beam irradiation to the manuscript read-out face. <P>SOLUTION: When the image of a manuscript conveyed is read by using CIS 50, the manuscript is irradiated with light by an LED array 52 provided in the CIS 50, and the reflected light from the manuscript is received by a line sensor 54. If the manuscript conveyed is made of a thin paper such as tracing paper, a lighting lamp 74 for reading out the other face of the manuscript originally is moved directly under a thrusting member 60, and the image is read out while the lighting lamp 74 is lightened. The light irradiated from the lighting lamp 74 is cast to the manuscript conveying face 60a of the thrusting member 60 via the manuscript, and the shadow of the manuscript image formed on the manuscript conveying face 60a of the thrusting member 60 is canceled by the light which has been irradiated from the LED array 52 and passed through the manuscript. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus that reads an image on an original, and more particularly, to an image reading apparatus that reads an image by irradiating the original with light using a light source and receiving reflected light from the original.

  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, a document conveyed in the sub-scanning direction is irradiated with light by a light source extending along the main scanning direction of the document, and reflected light reflected from the irradiated document is image sensor. The image on the original is read by receiving the light at (see, for example, Patent Document 1).

JP 2002-300394 A (page 3, FIG. 1)

By the way, in the image reading apparatus as described above, not only plain paper can be used as a document but also thin paper such as tracing paper can be used.
However, when the latter thin paper is used as a document, the following problems occur. In the case of thin paper, the light emitted from the light source tends to pass through the document. When the light passes through the document, the transmitted light is reflected by a background member (for example, the transport drum in Patent Document 1) provided on the back of the reading position, and is again transmitted through the document and received by the sensor. Things happen. At this time, the sensor acquires the shadow of the original image formed on the background member in addition to the original image as an image, and as a result, the read image is blurred.

In order to prevent the occurrence of such bleeding, for example, it is conceivable to perform reading while conveying the document in close contact with the background member. However, it is physically necessary to eliminate the gap between the document and the background member. It is difficult to. Although it is conceivable to remove blur by performing image processing such as TI separation (text-image separation) processing on the image data read by the light receiving sensor, it is extremely difficult to completely remove the generated blur. It is difficult to.
Note that such a problem is determined by the relationship between the amount of light applied to the original and the transmittance of the paper constituting the original, and is therefore limited to the case where thin paper such as tracing paper is used as the original. This may occur even when plain paper or the like is used.

  The present invention has been made to solve such technical problems, and an object of the present invention is to suppress bleeding in a read image caused by light irradiation on a reading surface of a document.

For this purpose, an image reading apparatus to which the present invention is applied includes a first light source that irradiates light on a document, a sensor that receives reflected light reflected from the document irradiated by the first light source, A counter member disposed opposite to the sensor with the document interposed therebetween, and a second light source for irradiating light to the surface of the counter member facing the sensor are included.
Here, the second light source may be characterized by irradiating light on the facing surface of the facing member indirectly through the document. The second light source may be characterized in that it emits light when the light transmittance of the paper constituting the document is high.

From another point of view, the image reading apparatus to which the present invention is applied includes a conveyance path through which the document is conveyed, a first light source that irradiates the first surface of the document from one side of the conveyance path, and the document. A first sensor for receiving reflected light from the first surface of the first document, and a first reading unit for reading image data on the first surface of the document, and irradiating the second surface of the document from the other side of the conveyance path A second light source and a second sensor for receiving reflected light from the second surface of the document, a second reading unit for reading image data on the second surface of the document, and the document by the second sensor And a controller that turns on the second light source in addition to the first light source when the first sensor reads the first surface image of the document without reading the second surface image.
Here, the controller may move the second light source to a predetermined position when turning on the second light source in addition to the first light source. The control unit may turn on only the first light source when the light transmittance of the document is lower than a predetermined value.

Further, from another point of view, the image reading apparatus to which the present invention is applied includes a conveyance path through which a document is conveyed, a first light source that irradiates the first surface of the document from one side of the conveyance path, and the document A first sensor for receiving reflected light from the first surface of the first document, and a first reading unit for reading image data on the first surface of the document, and irradiating the second surface of the document from the other side of the conveyance path A second light source and a second sensor for receiving reflected light from the second surface of the document, a second reading unit for reading image data on the second surface of the document, and the types of paper constituting the document And a selection receiving unit that receives a selection on the first side of the document without reading the image on the second side of the document with the second sensor. Only the first light source is turned on or the first light source And a setting unit for setting whether to turn on the source and the second light source.
Here, the setting unit turns on only the first light source when the selection accepting unit accepts a selection other than thin paper as the paper, and when the selection accepting unit accepts the selection of the thin paper as the paper, One light source and the second light source may be turned on.

  Furthermore, from another point of view, the image reading method to which the present invention is applied is an image reading method in an image reading apparatus that reads each image formed on both sides of a document by carrying the document once. When reading a document on which an image is formed on only one side, light is applied to the surface of the document on which the image is formed, and light is also applied to the other document surface on which no image is formed. Yes.

  According to the present invention, it is possible to suppress blur in a read image by canceling out a shadow caused by light transmitted through an original.

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.
FIG. 1 is a diagram showing an image reading apparatus to which the present embodiment is applied. This image reading apparatus is roughly divided into a document feeding device 10 that sequentially conveys documents from a stacked document bundle, a scanner device 70 that reads an image by scanning, and a processing device 80 that processes a read image signal.

  The document feeder 10 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 as an example of components of a paper feed unit. Also, a nudger roll 13 that conveys the document on the document tray 11 raised by the tray lifter 12, a feed roll 14 that conveys the document on the document tray 11 raised by the nudger roll 13 further downstream, and a nudger roll 13. A retard roll 15 is provided for feeding supplied documents one by one. In a first conveyance path 31 serving as a conveyance path through which the original is first conveyed, a takeaway roll 16 that conveys the originals that are being fed one by one to the downstream roll, and further conveys the original to the downstream roll. A pre-registration roll 17 for forming a loop, a registration roll 18 for supplying a document while adjusting the registration to the document reading unit after resuming rotation after stopping once, and a platen for assisting document conveyance during reading A roll 19 and an out-roll 20 for conveying the read document further downstream are provided. The first conveyance path 31 as a conveyance path is provided with a baffle 41 that rotates about a fulcrum according to the loop state of the conveyed document. Further, a CIS (Contact Image Sensor) 50 as a first reading unit 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. Further, 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, and the fourth transport. A fifth switch path 35 that guides the document switched back by the path 34 to the first transport path 31 having the pre-registration roll 17 and the like again, and discharges the document switched back by the fourth transport path 34 to the discharge tray 40. An exit provided in the transport path 36 and the sixth transport path 36 for switching the transport paths of the second discharge roll 24, the fifth transport path 35, and the sixth transport path 36 that transports the reversely discharged document to the first discharge roll 21. A switching gate 43 is provided. The third conveyance path 33, the fourth conveyance path 34, and the fifth conveyance path 35 constitute a reverse conveyance path.

  The nudger roll 13 is lifted up and held at the retracted position during standby, and descends to the nip position (original transport position) during transport of the document to transport 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 forms a loop by abutting the leading end of the document against the stopped registration roll 18. In the registration roll 18, the front end of the document bitten by the registration roll 18 is returned to the nip position when the loop is formed. When this loop is formed, the baffle 41 opens around the fulcrum and functions so as not to interfere with the loop formed on the document. In addition, the takeaway roll 16 and the pre-registration roll 17 hold a loop of the original being read. 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. In synchronization with the reading start timing, the stopped registration roll 18 starts rotating, the original is pressed against the second platen glass 72B (described later) by the platen roll 19, and the image is viewed from the lower surface direction by the CCD image sensor 78 described later. Data is read.

  The transport path switching gate 42 guides the document that has passed through the out-roll 20 to the second transport path 32 and discharges it to the discharge tray 40 or guides the document to the third transport path 33 in order to reverse the document. Can be switched to. The inverter pinch roll 23 is retracted in a state where a feed clutch (not shown) is turned off and the nip is opened when sequentially reading double-sided originals, and guides the originals to the fourth conveyance path (inverter 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 and discharged is conveyed to the second discharge roll 24 of the sixth conveyance path 36.

  The scanner device 70 as the second reading unit is configured to be able to place the document feeding device 10 described above, and is supported by the device frame 71 and conveyed by the document feeding device 10. The original image is being scanned. The scanner device 70 includes a first platen glass 72A for placing a document to be read in a stationary state on a device frame 71 forming a casing, and a light for reading a document being conveyed by the document feeder 10. The second platen glass 72B having the opening is provided.

  Further, the scanner device 70 is stationary under the second platen glass 72B, and scans the entire first platen glass 72A to read an image, and the light obtained from the full rate carriage 73 is input to the image coupling unit. A half-rate carriage 75 is provided. The full rate carriage 73 includes an illumination lamp 74 as a second 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. Furthermore, the scanner device 70 includes an imaging lens 77 that optically reduces the optical image obtained from the third mirror 76C, and a second sensor that photoelectrically converts the optical image formed by the imaging lens 77. A CCD (Charge Coupled Device) image sensor 78 and a drive substrate 79 to which the CCD image sensor 78 is attached 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. That is, in the scanner device 70, an image is formed on the CCD image sensor 78 as an image sensor using a so-called reduction optical system.

  Here, first, when 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 of the illumination lamp 74 of the full rate carriage 73 is irradiated on the surface to be read of the document, and the reflected light from the document is reflected in the order of the first mirror 76A, the second mirror 76B, and the third mirror 76C. Then, it is 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. The full rate carriage 73 is moved in this line direction (scanning main scanning direction) to read the next line of the document. By executing this over the entire original, reading of one page of the original 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. A 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 that has passed through the platen roll 19 of the document feeder 10 is imaged by the imaging lens 77 via the first mirror 76A, the second mirror 76B, and the third mirror 76C. 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 document conveyed by the document feeder 10 is read. After the leading edge of the original reaches the reading position of the second platen glass 72B, the original passes through the reading position of the second platen glass 72B, thereby completing one page of original reading 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 second surface of the document by the CCD image sensor 78 at the same time (when time is complete). It is possible to read the first side of the original by the CIS 50 (meaning that it is not coincident but the same as when the same original is conveyed).

  FIG. 2 is a diagram for explaining a reading structure using the CIS 50. As shown in FIG. 2, the CIS 50 is provided between the platen roll 19 and the out roll 20. One side (second side) of the original is pressed against the second platen glass 72B, and the image on the first side is read by the CCD image sensor 78. On the other hand, in the CIS 50, an image on the other side (first side) is read from the other side facing through the conveyance path for conveying the document. The CIS 50 includes a glass 51 disposed to face the conveyance path, an LED (Light Emitting Diode) array 52 as a first light source that transmits the first surface of the document through the glass 51, and an LED array. The SELFOC lens (registered trademark) 53 that condenses the reflected light from 52 and the line sensor 54 as a first sensor (sensor) that reads the light collected by the SELFOC lens 53 are provided. As the line sensor 54, a CCD, a CMOS (Complementary Metal Oxide Semiconductor) sensor, a contact type 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, an image is captured using a close-contact optical system composed of the SELFOC lens 53 and the line sensor 54 without using a reduction optical system, so that the structure can be simplified and the housing can be made compact. Power consumption can be reduced. When reading a color image, the LED array 52 is combined with LED light sources of three colors of R (red), G (green), and B (blue), and a set of three rows of RGB three-color sensors is used as the line sensor 54. Use it. Similar to the reading of the image on the second side, one line in the main scanning direction is simultaneously processed by the one-dimensional line sensor 54, and then one line in the next main scanning direction in the conveyed document is read. In this way, one page of the original is read in the sub-scanning direction on one side of the conveyed original.

  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 as an opposing member against which the original pressed by the control member 55 is abutted are provided in the conveyance path constituting the reading unit. ing. A guide member 61 is provided on the downstream side of the abutting member 60. 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 the direction orthogonal to the document conveyance path (that is, from the front surface to the rear surface of the document feeder 10). Is provided.

  Furthermore, since the CIS 50 employs the SELFOC lens 53 as an optical imaging lens, the depth of focus (field of view) is as shallow as about ± 0.3 mm, which is about 1 compared with the case where the scanner device 70 is used. The depth is less than / 13. For this reason, when reading by the CIS 50, it is required to set the reading position of the document within a predetermined narrow range. Therefore, in the present embodiment, the control member 55 is provided facing the conveyance path, the original is pressed against the abutting member 60 by the control member 55 and conveyed, and the original between the platen roll 19 and the out roll 20 is conveyed. It was configured to be able to stably control the attitude of the. The two-dot chain line arrow in FIG. 2 shows the movement of the document when the control member 55 is provided. It can be understood that the document is conveyed while being pressed against the abutting member 60 by the control member 55. That is, by reading the document conveyed by the control member 55 while being pressed against the abutting member 60, the sweetness of the focus when the CIS 50 having a shallow depth of field is used is improved.

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 apparatus 80 to which the present embodiment is applied is large, and includes a signal processing unit 81 that processes image information obtained from sensors (CCD image sensor 78 and CIS 50 (line sensor 54)), a document feeder 10 and a scanner. And a control unit 90 for controlling the device 70. The signal processing unit 81 has a function of performing predetermined image processing on each output from the CCD image sensor 78 that reads one side of the document and the line sensor 54 of the CIS 50 that reads the other side. The signal processing unit 81 includes an AFE (Analog Front End) 82 that performs analog signal processing on the output from the line sensor 54, and an ADC (Analog Digital Converter) 83 that converts the analog signal to a digital signal. . However, these functions can also be configured to be processed inside the CIS 50. The signal processing unit 81 includes an AFE 84 that performs analog signal processing on the output from the CCD image sensor 78 and an ADC 85 that converts the analog signal into a digital signal.

  Further, the signal processing unit 81 is provided with two systems of image processing circuits for performing various processes such as shading correction and offset correction on the digital signal, and for the single-sided image data read by the CCD image sensor 78. A first image processing circuit 100 that performs image processing, and a second image processing circuit 200 that performs image processing on the other one-sided image data read by the CIS 50. The output from these image processing circuits is output to an IOT (Image Output Terminal) such as a printer or a host system such as a personal computer (PC).

  On the other hand, a control unit 90 as a control unit, a selection receiving unit, and a setting unit includes an image reading control 91 that controls the entire document feeding device 10 and the scanner device 70, including double-sided scanning control and single-sided scanning control. A CCD / CIS control 92 for controlling the image sensor 78 and the CIS 50, a lamp control 93 for controlling the LED array 52 of the CIS 50 and the illumination lamp 74 of the full rate carriage 73 in accordance with the reading timing, and on / off of the motor in the scanner device 70, etc. Scanning control 94 for controlling the scanning operation by the full-rate carriage 73 and the half-rate carriage 75, motor control in the document feeder 10, various roll operations, feed clutch operations, gate switching operations, etc. And a conveying mechanism control 95 for controlling. 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.

  FIG. 4 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 can be recognized by selection from the user using a control panel (not shown) provided on the scanner device 70, for example. 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 single-sided reading by fixing the original, reading is performed by the CCD image sensor 78 while moving the full-rate carriage 73 and the half-rate carriage 75 in the above-described procedure.

  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 can also be recognized by selection from the user using a control panel (not shown) provided on the scanner device 70, for example.

  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 104). The determination in step 104 is made based on selection from the user using a control panel (not shown) provided on the scanner device 70, 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 105). 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 according to user settings. If it is determined in this step 105 that the image quality is important, double-sided reading is executed by the reverse pass (step 106). That is, without reading by the CIS 50, the CCD image sensor 78 reads both the first side of the original and the second side of the original. 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, even when white / black reading is performed in step 104 or color image output is required in step 105, for example, when subtle shades 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 107). 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.

  If the original is a single-sided original in step 103 described above, it is next determined whether or not the paper for calibrating the original is tracing paper (step 108). The determination in step 108 is made based on a selection from the user using a control panel (not shown) provided on the scanner device 70. If the original is tracing paper (thin paper) in step 108, single-sided reading is performed by one pass using the CIS 50 (step 109). In single-sided reading by one pass using the CIS 50, the original is placed on the original tray 11 so that a single-sided original part exists downward, and the original is conveyed and read in this state. On the other hand, if the original is not tracing paper in step 108, single-sided reading is performed by one pass using the CCD image sensor 78 (step 110). In one-sided reading by one pass using the CCD image sensor 78, the document is placed on the document tray 11 so that a one-sided document portion exists upward, and the document is conveyed and read in this state.

  Note that the processing flow shown in FIG. 4 is simplified, and when reading a black and white original in double-sided original reading, double-sided simultaneous reading in step 107 is executed, and in the case of a color original, the reverse path in step 106 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.

Next, a method for conveying a document in each document reading mode for document flow reading will be described with reference to FIGS.
FIGS. 5A and 5B are diagrams showing a single-sided reading mode by one pass shown in steps 109 and 110 in FIG. 4 and a document pass in the double-sided simultaneous reading mode by one pass shown in step 107. is there. As shown in FIG. 5A, 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. 5B, 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, the CCD image sensor 78 (when the original is not tracing paper) or the CIS 50 (when the original is tracing paper) shown in FIG. The reading that was made is made. In the case of simultaneous reading on both sides by one pass, the second surface is read using the CCD image sensor 78 of the scanner device 70, and the first 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. 6A to 6D are diagrams for explaining the double-sided reading mode by the inversion path shown in step 106 of FIG. As shown in FIG. 6A, 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. 6B.

  The document supplied to the fifth conveyance path 35 is again supplied to the first conveyance path 31. Then, as shown in FIG. 6C, 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. 6A, and the second surface that is different from the first surface 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. 6C, 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.

FIG. 7 is a diagram for explaining single-sided reading by one pass using the CIS 50 in step 109 described above.
In the image reading apparatus according to the present embodiment, when performing single-sided reading by one pass using the CIS 50, that is, when scanning and reading a document on which a single-sided image is formed on tracing paper, the full-rate carriage 73 is abutted. The illumination lamp 74 is moved immediately below the member 60 and the illumination lamp 74 provided on the full rate carriage 73 is turned on. The light emitted from the illumination lamp 74 wraps around the back side of the document (tracing paper) being conveyed via the first platen glass 72A and the second platen glass 72B, and is indirectly abutted by reflection, scattering, etc. Irradiation is also performed on the document conveying surface 60 a of the member 60.

  Here, FIG. 8 is a schematic diagram for explaining the cause of bleeding in the read image data. When reading an image using the CIS 50, the light emitted from the LED array 52 toward the document is reflected according to the image formed on the document and received by the line sensor 54. Specifically, the amount of reflected light is small in a portion where an image is formed, and the amount of reflected light is large in a white background portion where an image is not formed. Further, part of the light emitted from the LED array 52 toward the document passes through the tracing paper constituting the document, reaches the document transport surface 60a of the abutting member 60, and is reflected by the document transport surface 60a. Then, after passing through the tracing paper again, it is received by the line sensor 54. In general, it is difficult to dispose the LED array 52 and the line sensor 54 at the same position, and the LED array 52 is usually disposed so as to be shifted in the sub-scanning direction with respect to the line sensor 54. For this reason, the shadow of the image portion of the original is formed on the original conveying surface 60a of the abutting member 60 at a position shifted from the actual original image position due to the light irradiation by the LED array 52. Then, the line sensor 54 receives the reflected light in a state in which the deviation in the sub-scanning direction has occurred from the document conveyance surface 60a. As a result, the image received by the line sensor 54 also includes an image from the document conveyance surface 60a adjacent to the image from the document, and blurring occurs.

On the other hand, in the present embodiment, when the one-side reading by the CIS 50 is performed, the illumination lamp 74 indirectly irradiates the document conveying surface 60a with light. Thus, the shadow of the original image formed on the original conveying surface 60a of the abutting member 60 is canceled out by the light emitted from the LED array 52 and transmitted through the original. As a result, it is possible to prevent the shadow formed on the original conveying surface 60a from being received by the line sensor 54 and to prevent image blurring caused by this.
Further, since no shadow that causes blurring occurs, it is not necessary to perform complicated image processing, parameter setting, and the like, and the configuration can be simplified and the cost can be reduced.
In particular, in the present embodiment, since the illumination lamp 74 provided for reading another surface different from the reading surface by the CIS 50 is used to irradiate the document conveying surface 60a, it is necessary to provide a new light source. There is an advantage that there is no.
Furthermore, in this embodiment, since it is not necessary to narrow the gap between the original and the original conveying surface 60a in order to suppress the occurrence of shadows, it is possible to read and read originals having various thicknesses.

1 is a diagram illustrating an image reading apparatus according to an embodiment. It is a figure for demonstrating the reading structure using CIS. It is a figure for demonstrating a processing apparatus. It is the flowchart which showed an example of the process performed by image reading control. (a), (b) is a figure for demonstrating the single-sided reading mode by 1 pass, and the original pass of the double-sided simultaneous reading mode by 1 pass. (a)-(d) is a figure for demonstrating the double-sided reading by an inversion path | pass. It is a figure for demonstrating the single-sided reading by 1 pass using CIS. It is a figure for demonstrating the cause which a bleeding produces in the read image data.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Document feeder, 11 ... Document tray, 31 ... 1st conveyance path, 32 ... 2nd conveyance path, 33 ... 3rd conveyance path, 34 ... 4th conveyance path, 35 ... 5th conveyance path, 36 ... 6th Transport path, 40 ... discharge tray, 50 ... CIS, 51 ... glass, 52 ... LED array, 53 ... Selfoc lens, 54 ... line sensor, 70 ... scanner device, 78 ... CCD image sensor, 80 ... processing device, 81 ... Signal processing unit, 90 ... control unit, 91 ... image reading control, 92 ... CCD / CIS control, 93 ... lamp control, 94 ... scan control, 95 ... transport mechanism control, 100 ... first image processing circuit, 200 ... second Image processing circuit

Claims (9)

A first light source for irradiating the document with light;
A sensor for receiving reflected light reflected from the document irradiated by the first light source;
A facing member disposed to face the sensor with a document interposed therebetween;
An image reading apparatus including: a second light source that irradiates light to a surface of the facing member facing the sensor.   The image reading apparatus according to claim 1, wherein the second light source irradiates light to the facing surface of the facing member indirectly through a document.   The image reading apparatus according to claim 1, wherein the second light source emits light when the light transmittance of the paper constituting the document is high. A transport path through which the document is transported;
A first light source that irradiates the first surface of the document from one side of the conveyance path and a first sensor that receives reflected light from the first surface of the document; A first reading unit for reading image data;
A second light source that irradiates the second surface of the document from the other side of the conveyance path and a second sensor that receives reflected light from the second surface of the document; A second reading unit for reading image data;
When the second sensor reads the image on the first surface of the document without reading the image on the second surface of the document with the second sensor, the second sensor in addition to the first light source is used. An image reading apparatus including a control unit that turns on the light source.   The image reading apparatus according to claim 4, wherein the control unit moves the second light source to a predetermined position when turning on the second light source in addition to the first light source.   The image reading apparatus according to claim 4, wherein the control unit turns on only the first light source when the light transmittance of the document is lower than a predetermined value. A transport path through which the document is transported;
A first light source that irradiates the first surface of the document from one side of the conveyance path and a first sensor that receives reflected light from the first surface of the document; A first reading unit for reading image data;
A second light source that irradiates the second surface of the document from the other side of the conveyance path and a second sensor that receives reflected light from the second surface of the document; A second reading unit for reading image data;
A selection accepting unit for accepting selection of the types of paper constituting the document;
The type of the sheet received by the selection receiving unit when the first sensor reads the first surface of the document without reading the second surface image of the document by the second sensor. And a setting unit that sets whether to turn on only the first light source or whether to turn on the first light source and the second light source.   The setting unit turns on only the first light source when the selection accepting unit accepts a selection other than the thin paper as the paper, and accepts selection of the thin paper as the paper at the selection accepting unit The image reading apparatus according to claim 7, wherein the first light source and the second light source are turned on. An image reading method in an image reading apparatus that reads each image formed on both sides of a document by conveying the document once,
When reading a document on which an image is formed on only one side, light is applied to the surface of the document on which the image is formed, and light is also applied to the other document surface on which no image is formed. Image reading method.

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