JP2008199375A - Reader and copier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To excellently suppress the so-called rear copying by a method different from a conventional method. <P>SOLUTION: A reader has an original pushing section 125 in the reading section 12. The original pushing section 125 has a reflecting layer on a surface opposed to an original base 12c. A display body of a memory liquid crystal such as a cholesteric liquid crystal is used as the reflecting layer, and the reflecting layer is composed of a plurality of pixels displaying a gradation specified to a control section. The displayed gradation is made to differ when an original capable of generating the rear copying is read and when an original not generating the rear copying is read. Accordingly, since the reflectance of a light from the reflecting layer is changed, the generation of the rear copying can be suppressed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for suppressing so-called show-through.

When copying a sheet-like document (soft copy / hard copy), if an image is also formed on the back side of the document, a mirror image of the image on the back side is reflected on the copied document. May occur. The show-through occurs particularly noticeably when the original document is thin and the document has a high light transmittance. Conventional techniques for suppressing show-through are disclosed in, for example, Patent Documents 1 to 4.
JP-A-8-258466 Japanese Patent Laid-Open No. 11-284810 JP 2002-271576 A JP 2005-286922 A

However, all of the above-described conventional techniques have disadvantages. For example, since the technique described in Patent Document 2 enables replacement of a member that presses a document, the operator's work is complicated. Further, the technique described in Patent Document 3 is provided with a plurality of color document pressing members that move mechanically. However, in order to cope with various show-through, the number of colors must be increased, and the apparatus Increases in size. Further, since the technique described in Patent Document 4 involves the movement of the document, the operator's work is complicated and there is a concern about the displacement of the document.
The present invention has been made in view of such circumstances, and an object thereof is to satisfactorily suppress show-through by a method different from the conventional one.

The reading apparatus according to the present invention is disposed so as to face an irradiation unit that irradiates light on a sheet-like object on which an image is formed, and a surface opposite to a surface irradiated with light by the irradiation unit of the sheet-like object. In addition, the transmitted light transmitted through the sheet-like material among the light irradiated by the irradiation unit is reflected in the same direction as the reflected light received by the generation unit with a degree according to a specified gradation. Receiving the reflected light on the sheet-like material of the light irradiated by the irradiating means, and generating the image data according to the amount of the received light And generating means.
In this case, it is desirable that the reflecting means is configured to exhibit a gradation specified by the gradation control means.
According to such a reading apparatus, it is possible to adjust the amount of light that passes through the sheet-like material and reaches the generation unit by changing the degree of reflection by the reflection unit, thereby suppressing show-through. it can.
The sheet-like material includes, for example, a sheet-like material made of paper, plastic, or other materials.

  Further, in the present invention, a detection unit that detects show-through occurring in the sheet-like material is provided, and the gradation control unit designates a gradation according to a detection result of the show-through by the detection unit to the reflection unit. You may employ | adopt the structure to do. In this way, it is possible to specify a gradation according to the presence or absence and the degree of show-through.

  The detecting means may detect show-through using the generating means, or may detect show-through using a separate configuration. For example, in the latter configuration, the sheet-like object is provided with a conveying unit that conveys the sheet-like object, and the irradiation unit irradiates the sheet-like object that is conveyed by the conveying unit and the show-through is detected by the detecting unit. It may be configured to. This is an example when the present invention is applied to a so-called sheet feed (sheet fed) type scanner.

  The present invention may also be applied to a so-called flatbed scanner. For example, the moving unit may be configured to move the irradiation unit so that the entire surface of the sheet-like material is irradiated with light, and the reflection unit may have an area facing the entire surface of the sheet-like material. Good. In this case, the reflecting means includes a plurality of reflecting portions exhibiting gradations specified by the gradation controlling means in the moving direction of the moving means, and the gradation controlling means includes a plurality of reflecting portions. On the other hand, a configuration may be adopted in which gradations are specified in order in the moving direction.

  Further, in the present invention, the reflecting means includes a plurality of reflecting portions exhibiting a gradation specified by the gradation controlling means in a predetermined direction, and the detecting means is arranged in the sheet-like object with respect to the predetermined direction. The generated show-through and both ends of the sheet-like material are detected, and the gradation control unit is arranged to be outside the both ends of the sheet-like material detected by the detection unit when the irradiation unit emits light. When the reflection part is present, a plurality of reflection parts reflect the transmitted light so that a reflection part that does not exist outside both ends of the sheet-like object has a higher degree of reflection than the transmission light. You may employ | adopt the structure which designates a gradation for each of the said reflection parts. In this way, when reading a sheet-like material smaller than the width of the reflecting means in the predetermined direction, image data that does not include the outside of both ends of the sheet-like material, or image data that makes the outside less visible than the both ends. Obtainable.

  In the present invention, the gradation control means includes a first mode that reflects the transmitted light at a first degree, and a second mode that reflects the transmitted light at a second degree that is higher than the first degree. You may employ | adopt the structure which controls by this mode. In this way, it is possible to select and select a mode according to the original. In this case, the mode may be selected by the operator, or the image data generated by the reading device in both modes may be selected by the operator.

  When the control is performed in the first mode and the second mode, the generation unit is configured to control the same sheet-like material in the first mode. The first image data is generated at the same time, and the second image data is generated when the gradation control means performs control in the second mode, and one of the first and second image data is generated. A configuration may be provided that includes a combining unit that generates combined image data. In this way, for example, even when show-through occurs in a part of the second image data, it is possible to replace the portion where the show-through occurs with the image of the first image data. Further, for example, even if there is a portion where the contrast is insufficient in the first image data, the portion can be replaced with the image of the second image data.

  In the present invention, the generation unit includes an image sensor that receives light in a predetermined area, and the exposure amount in the image sensor when the gradation control unit reflects the transmitted light at a first degree. Alternatively, the gradation control unit may include an exposure control unit that increases an exposure amount when the transmitted light is reflected at a second degree higher than the first degree. In this way, it is possible to correct the difference in image quality caused by the gradation difference of the reflecting means.

In the present invention, the reflecting means may have a reflecting portion using a memory liquid crystal. Examples of such memory liquid crystal include cholesteric liquid crystal. Further, the reflection part may be configured to exhibit gradation by an electrophoresis method.
Furthermore, it is more desirable that the reflecting portion has a flexible structure. In the case of this configuration, for example, it can be said that it is particularly suitable for reading a sheet-like material having irregularities in a flatbed scanner.

  Further, the present invention can be applied not only to the reading apparatus but also to other modes such as a copying apparatus. For example, it may be configured to include the above-described reading device and an image forming unit that forms an image according to the image data generated by the generating unit.

Embodiments of the present invention will be described below with reference to the drawings.
In the embodiment described below, the document is a sheet-like material having images formed on both sides thereof. In the following, the surface to be read of the document is referred to as “front surface”, and the opposite surface is referred to as “back surface”. Further, it is assumed that the document can show through, and the image formed on the surface is represented by two gradations of white (color of the document itself) and black (color of color material such as ink and toner). Suppose that

[First Embodiment]
FIG. 1 is a block diagram showing the overall configuration of a reading apparatus 10 according to the first embodiment of the present invention. The reading device 10 according to the present embodiment is a so-called flatbed scanner, and reads an image formed on a document while moving a light source. The configuration of the reading device 10 is roughly divided into a control unit 11, a reading unit 12, an output unit 13, and an operation unit 14.

  The control unit 11 includes an arithmetic device such as a CPU (Central Processing Unit) and a memory, and controls the operation of the reading device 10 based on an operation signal output from the operation unit 14. The reading unit 12 optically reads a document and generates image data representing a reading result. The output unit 13 outputs the image data generated by the reading unit 12 to a predetermined output destination. The output unit 13 performs data communication using an interface compliant with a predetermined standard, for example, USB (Universal Serial Bus) or IEEE1394. The output destination of the image data is, for example, an external device connected via communication means or a storage medium such as a memory. The operation unit 14 receives an instruction from the operator and outputs an operation signal corresponding to the instruction. The instruction from the operator may be supplied from an external device via the output unit 13.

FIG. 2 is a diagram illustrating a configuration of the reading unit 12. The reading unit 12 includes a document cover 12a and a housing 12b. The document cover 12a is configured to be rotatable about one end thereof so that the document can be placed. Further, the document cover 12a includes a document pressing portion 125 at a portion facing the back surface of the document. The housing 12b includes a document table 12c on a surface facing the document cover 12a. The document table 12 c is a transparent plate member made of glass or the like, and supports the document so as to be sandwiched between the document pressing unit 125. At this time, the document has the front surface facing the document table 12 c and the back surface facing the document pressing unit 125. In addition, a carriage 12d, a light source 121, an imaging lens 122, an imaging element array 123, and a motor 124 are provided inside the housing 12b.
In the present embodiment, a so-called reduction optical system is used for the reading unit 12, but of course, a so-called equal-magnification optical system can also be used.

  The carriage 12d movably supports the light source 121, the imaging lens 122, and the imaging element array 123. The light source 121 emits light toward the surface of the document. The light source 121 is provided such that the light irradiation direction forms a predetermined angle with respect to the document table 12c, and has the same length as the document table 12c with respect to the direction perpendicular to the paper surface of FIG. The light source 121 is, for example, a cold cathode fluorescent lamp or a xenon fluorescent lamp. The imaging lens 122 forms an image of a part of the reflected light reflected from the original in the light emitted from the light source 121 toward the image sensor array 123.

  In the present embodiment, the light source 121, the imaging lens 122, and the imaging element array 123 are all moved. However, the positions of the imaging lens 122 and the imaging element array 123 are fixed, and the reflected light travels toward them. Thus, a configuration in which a mirror or the like is provided may be used.

  The image sensor array 123 receives the reflected light imaged by the imaging lens 122 at a predetermined position, and generates an image signal corresponding to the received light amount. The imaging element array 123 includes a plurality of imaging elements such as a CCD (Charge Coupled Device) in a row. The direction in which the imaging elements are arranged is a direction perpendicular to the paper surface of FIG. This direction is hereinafter referred to as “main scanning direction”. The image signal generated by each image sensor has a larger value as the amount of received light increases. The image signal is converted into image data, which is digital data, by an AD converter (not shown) of the reading unit 12. The number of gradations of the image data is arbitrary, but is 8 bits (256 gradations), for example.

  The motor 124 moves the carriage 12d in response to an instruction from the control unit 11. When the light is emitted from the light source 121, the motor 124 moves the carriage 12d so that the light is evenly irradiated on the entire document surface. The moving direction of the carriage 12d is a direction indicated by an arrow S in FIG. 2, and is a direction from one end of the document table 12c to the other end. This direction is hereinafter referred to as “sub-scanning direction”.

  FIG. 3 is a diagram illustrating a configuration of the document pressing unit 125. The document pressing unit 125 includes an elastic layer 125a and a reflective layer 125b. The document pressing unit 125 includes a drive unit that drives a display body to be described later. The elastic layer 125a is a layer made of an elastic material such as sponge, and urges the document toward the document table 12c when the document cover 12a is closed. The reflective layer 125 b is a display body bonded to the elastic layer 125 a and changes the color (gradation) according to the designation from the control unit 11. The reflective layer 125b has the same size as the document table 12c. As the display body of the reflective layer 125b, for example, a memory liquid crystal can be used. Here, the memory liquid crystal is liquid crystal that can maintain a display state (that is, gradation) without applying a voltage. As the memory liquid crystal, for example, cholesteric liquid crystal is used. The reflective layer 125 b has pixels of a plurality of rows and a plurality of columns, and each pixel exhibits a gradation corresponding to the gradation data supplied from the control unit 11. Each pixel of the reflective layer 125b has the highest reflectance when the maximum gradation data is given, and the lowest reflectance when the smallest gradation data is given. The reflective layer 125b is provided so that the row direction of the arranged pixels matches the above-described main scanning direction and the column direction matches the above-described sub-scanning direction. Further, although the number of gradations of each pixel of the reflective layer 125b is arbitrary, it is desirable that the number of gradations is large in view of the object of satisfactorily suppressing show-through.

  For convenience of explanation, here, the color of the pixel of the reflective layer 125b when the reflectance is the highest is referred to as “white”, and the color of the pixel of the reflective layer 125b when the reflectance is the lowest is “black”. That's it. However, the actual color of the pixel of the reflective layer 125b is not necessarily white or black due to the composition of the reflective layer 125b or the like. For example, cholesteric liquid crystals tend to have a lower brightness than so-called white even when the reflectance is highest.

  The configuration of the reading device 10 is as described above. With this configuration, the reading device 10 optically reads the surface of the document, generates image data representing the reading result, and outputs the image data. The reading apparatus 10 according to the present embodiment performs reading a plurality of times on the same document, and changes the conditions for subsequent reading based on the immediately preceding reading result. Details of this operation are as described below.

  FIG. 4 is a flowchart showing a reading operation by the reading device 10. This reading operation is executed when the control unit 11 acquires an operation signal instructing the start of the reading operation. Therefore, at the start of this reading operation, it is assumed that the document is placed on the document table 12c. As shown in the figure, first, the control unit 11 supplies gradation data designating gradations to the document pressing unit 125, and changes the color of each pixel of the reflective layer 125b to white (step Sa1). When the gradation data is supplied, the control unit 11 instructs the motor 124 to move the carriage 12d and causes the document to be read (step Sa2). At this time, the reading unit 12 generates image data representing the document.

  Next, the control unit 11 acquires the image data generated by the reading unit 12, and analyzes the image represented by this image data (step Sa3). At this time, the control unit 11 performs analysis for classifying the region represented by the image data into any one of “background region”, “image region”, and “show-through region”. The control unit 11 performs this analysis by referring to the luminance level of each pixel of the image data, that is, the gradation value.

FIG. 5 is a diagram illustrating an analysis result of certain image data, in which the gradation value of each pixel of the image data is displayed as a histogram. In the figure, the horizontal axis represents the gradation value, and the larger the value, the closer to white, and the smaller the value, the closer to black. The vertical axis represents the frequency, that is, the appearance frequency of the pixel representing the gradation value.
The control unit 11 classifies the regions based on predetermined threshold values Th ₁ and Th ₂ . The control unit 11 sets an area formed by pixels having a gradation value equal to or lower than the threshold Th ₁ as an image area, an area formed by pixels having a gradation value equal to or higher than the threshold Th ₂ as a background area, and other halftones. Let the area be a show-through area. When the areas are specified in this way, the control unit 11 calculates the area of each area by integrating the number of pixels in each area. At this time, when the calculated area of the show-through area is greater than or equal to a predetermined ratio with respect to the entire area represented by the image data, the control unit 11 indicates that show-through that cannot be ignored is generated in the image data. I reckon. On the other hand, when the area of the show-through area is less than a predetermined ratio with respect to the entire area represented by the image data, the control unit 11 has no show-through in the image data or can be ignored. It is considered.

  Subsequently, the control unit 11 determines whether or not the show-through area exceeds a predetermined ratio (step Sa4). In other words, the control unit 11 determines whether or not show-through has occurred. Here, when the show-through area is equal to or smaller than the predetermined ratio (step Sa4: YES), the control unit 11 regards the image data generated by the above-described processing of step Sa2 as an output target, and via the output unit 13 Output (step Sa5). On the other hand, when the show-through area exceeds a predetermined ratio (step Sa4: NO), the control unit 11 does not set the image data generated by the process of step Sa2 described above as an output target, and generates image data again. In this case, the control unit 11 supplies gradation data to the document pressing unit 125, and changes the color of each pixel of the reflective layer 125b to a color having a lower reflectance than white (step Sa6).

  In addition, the color determined in the process of step Sa6 is not specifically limited. For example, the control unit 11 may decrease the gradation value by a value determined each time this process is executed, or may determine the gradation value according to the calculated ratio of the show-through area. In the latter case, it is desirable for the control unit 11 to darken the color (close to black) as the calculated ratio of the show-through area increases.

  After determining the color of each pixel of the reflective layer 125b in this way, the control unit 11 causes the original to be read again after the color of each pixel of the reflective layer 125b has changed (step Sa2). Then, the control unit 11 repeats the subsequent processing until the show-through area becomes a predetermined ratio or less. In other words, the control unit 11 repeats generation and analysis of image data while gradually bringing the color of each pixel of the reflective layer 125b closer to black until image data that can be ignored is obtained.

  The reading operation of the reading device 10 is as described above. By operating in this way, the reading device 10 can output image data in which show-through is suppressed. This is to suppress the incidence of light transmitted through the document out of the light source 121 from entering the image sensor array 123 by changing the reflectance of the portion (reflective layer 125b) facing the back surface of the document. Because it can be done.

6 and 7 are schematic diagrams for explaining the operation of the reading apparatus 10 according to the present embodiment. FIG. 6 illustrates a case where each pixel of the reflective layer 125b is white, and FIG. 7 illustrates a case where each pixel of the reflective layer 125b is black. In these figures, the intensity of light is represented by the thickness of the arrows. For convenience of explanation, the reflective layer 125b and the document D are separated from each other in these drawings, but they are in close contact with each other during actual reading. Therefore, the arrows shown next to each other in parallel in these figures actually travel on substantially the same path. That is, the reflected light reflected from the document D travels along the substantially same path as the transmitted light that has been transmitted through the document D and reflected by the reflection layer 125b and again transmitted through the document D.
Now, the light emitted from the light source 121 and incident light Li _1, Li ₂ and Li _3. Incident light Li ₁ is incident on a region where an image is formed on the surface of the document D, and incident light Li ₃ is incident on a region where an image is formed on the back surface of the document D. Further, the incident light Li ₂ is incident on a region where the image of the document D is not formed (that is, the background region).

Most of the incident light Li ₁ is absorbed or scattered by the image of the surface of the document D. Therefore, both the reflected light Lr _{1 of} the incident light Li _{1 on} the surface of the document D and the transmitted light Lt ₁₁ transmitted through the document D are very small. The transmitted light Lt ₁₁ is further reduced in intensity when reflected by the reflective layer 125b and when transmitted through the document D. Therefore, the transmitted light Lt ₁₂ has a lower intensity than the transmitted light Lt ₁₁ , and the transmitted light Lt ₁₃ has a lower intensity than the transmitted light Lt ₁₂ .
Part of the incident light Li ₂ is reflected by the surface of the document D. Further, since there is no image that impedes transmission, the incident light Li ₂ passes through the document D more than the incident light L ₁ and the incident light L ₃ . As a result, the reflected light Lr ₂ is higher in intensity than the reflected light Lr ₁ , and similarly, the transmitted lights Lt ₂₁ , Lt ₂₂ and Lt ₂₃ are stronger than the transmitted lights Lt ₁₁ , Lt ₁₂ and Lt ₁₃ , respectively. Get higher.

On the other hand, the incident light Li ₃ is in that a part is reflected by the surface of the document D is similar to the incident light Li _2, since the image is formed on the back side of the document D, it is transmitted through the document D the amount of light is less than that of the incident light Li _2. Accordingly, the reflected light Lr ₃ of the incident light Li _{3 on} the surface of the document D has substantially the same intensity as the reflected light Lr _2, and the transmitted lights Lt ₃₁ , Lt ₃₂ and Lt ₃₃ of the incident light Li ₃ are transmitted light Lt _11. , Lt ₁₂ and Lt ₁₃ have substantially the same strength. Since the light received by the image sensor array 123 is a light that combines the reflected light Lr ₃ and the transmitted light Lt ₃₃ , the transmitted light is compared with the light that combines the reflected light Lr ₂ and the transmitted light Lt _23. The intensity differs by an amount corresponding to the difference between Lt ₃₃ and transmitted light Lt ₂₃ . When this difference in intensity becomes significant, it is recognized as show-through in the image data.

When the case shown in FIG. 6 is compared with the case shown in FIG. 7, the reflectance of the reflective layer 125 b is different, and thus the intensity of the transmitted light reflected by the reflective layer 125 b is different. Then, in the case illustrated in FIG. 7, the difference between the transmitted light Lt ₃₃ and the transmitted light Lt ₂₃ is relatively small as compared with the case illustrated in FIG. 6. As a result, the difference in intensity of the light received by the image sensor array 123 is suppressed, and the image data is less likely to be recognized as show-through.

However, comparing the case shown in FIG. 7 with the case shown in FIG. 6, in the case shown in FIG. 7, the intensity of the transmitted light Lt ₁₃ , Lt ₂₃ and Lt ₃₃ decreases as a whole. That is, the intensity of light also decreases in the original white portion of the document D. Therefore, when the reflectance of the reflective layer 125b is lowered, the contrast of the image represented by the image data is lowered.

  The reading apparatus 10 according to the present embodiment generates image data by changing the reflectance of the reflective layer 125b in a stepwise manner when reading a document that causes show-through. Therefore, according to the reading device 10 of the present embodiment, it is possible to output image data with good image quality while maintaining a balance between contrast reduction and suppression of show-through. For example, when a 32-gradation display body is used for the reflective layer 125b, the reflectance can be adjusted to 32 levels.

  Further, the reading apparatus 10 of the present embodiment can perform gradation control without mechanically moving or replacing the reflective layer 125b. In addition, the reading device 10 according to the present embodiment can perform reading a plurality of times while placing a document. Therefore, the reading apparatus 10 of this embodiment can perform gradation control without human intervention, and there is almost no need to increase the size of the apparatus even when multi-gradation control is performed.

[Second Embodiment]
Subsequently, a second embodiment of the present invention will be described. In this embodiment, the present invention is applied to a so-called sheet feed type scanner.
When this embodiment is compared with the first embodiment described above, in addition to the difference between whether the conveyance target is a light source or a document, the manner of detecting show-through is greatly different. The reading apparatus 10 of the first embodiment uses the reading unit 12 as a means for detecting show-through, but in the present embodiment, means for detecting show-through in view of the conveyance target being a document. Is provided separately from the reading unit.

  FIG. 8 is a block diagram showing the overall configuration of the reading device 20 of the present embodiment. The configuration of the reading device 20 is roughly divided into a control unit 21, a reading unit 22, a reflection unit 23, a back surface detection unit 24, a document transport unit 25, an output unit 26, and an operation unit 27. Among these, the configurations of the output unit 26 and the operation unit 27 are substantially the same as the configurations of the output unit 13 and the operation unit 14 described above. Moreover, although the control part 21 differs in the process to perform, the hardware constitutions are substantially the same as the control part 11 mentioned above.

  FIG. 9 is a diagram illustrating the configuration of the reading unit 22, the reflection unit 23, the back surface detection unit 24, and the document conveyance unit 25. In the figure, a broken line indicates a document transport path and its direction. The reading unit 22 includes a light source 221 and a sensor 222. The reading unit 22 of the present embodiment is a so-called CIS (Contact Image Sensor) system, and is a 1 × optical system. The reading unit 22 includes an AD converter similar to the reading unit 12 of the first embodiment, and outputs the generated image signal as image data.

  The light source 221 irradiates light on the surface of the document. The light source 221 is provided such that the light irradiation direction forms a predetermined angle with respect to the surface on which the reflection unit 23 is provided, and is approximately the same length as the reflection unit 23 in the direction perpendicular to the paper surface of FIG. Have The light source 221 is, for example, an LED (Light Emitting Diode). The sensor 222 includes a lens array and an imaging element array having a length similar to that of the light source 221, receives light reflected from the light source 221 and reflected from the document at a predetermined position, and corresponds to the amount of light received. An image signal is generated. The imaging element array of the sensor 222 is, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor.

  The reflection unit 23 includes a display body similar to the reflection layer 125b of the first embodiment on the surface facing the document. Since the reflecting portion 23 is fixed at a position where light is emitted from the light source 221, it is not necessary to have the same length as that of the original in the conveyance direction of the original, and about 1 cm is sufficient. Note that the reflection unit 23 has the same length as that of the document in the direction orthogonal to the document conveyance direction. The reflection unit 23 includes a drive circuit that drives the display body.

  The back surface detection unit 24 includes a sensor that reads the back surface of the document, and generates image data representing the back surface of the document. The back surface detection unit 24 generates image data before the reading unit 22 generates image data. The configuration of the back surface detection unit 24 is the same as the configuration of the reading unit 22, but the image quality (number of gradations, resolution, etc.) may not be equal to or higher than that of the reading unit 22. This is because the image data generated by the back surface detection unit 24 is used to determine whether or not the document causes show-through, and does not constitute image data to be read.

  The document conveyance unit 25 includes a plurality of conveyance rollers 251. The conveyance roller 251 conveys the document along a predetermined path by a pair of opposed roll-shaped members. The conveyance roller 251 is driven by a motor or the like (not shown) and conveys the document at a predetermined speed. In addition, the conveyance roller 251 may exist more than what was shown in FIG.

  The configuration of the reading device 20 is as described above. With this configuration, the reading device 20 optically reads the front surface and the back surface of the document, and generates and outputs image data representing the reading result of the front surface. The reading apparatus 20 according to the present embodiment generates image data representing the back side of the document from the image signal generated by the back surface detection unit 24, and performs gradation control of the reflection unit 23 based on the content of the image data represented by the image data. After that, image data representing the back side of the document is generated. Details of this operation are as described below. In the following, the image data representing the front side of the document is referred to as “front side image data”, and the image data representing the back side of the document is referred to as “back side image data” to distinguish between the two.

  FIG. 10 is a flowchart showing a reading operation by the reading device 20. This reading operation is performed while the control unit 21 transports the document to the document transport unit 25. As shown in the figure, first, the control unit 21 causes the back side detection unit 24 to read the back side of the document (step Sb1). At this time, the back surface detection unit 24 generates back surface image data.

  Next, the control part 21 acquires the back surface image data produced | generated by the back surface detection part 24, and analyzes the image which this back surface image data represents (step Sb2). At this time, the control unit 21 calculates a ratio of pixels whose color is not white among all the pixels constituting the image data, and when the calculated ratio exceeds a predetermined ratio, an image is formed on the back side of the document. It is considered. On the other hand, when the calculated ratio is equal to or less than the predetermined ratio, the control unit 21 considers that no image is formed on the back side of the document. Subsequently, the control unit 21 determines whether or not the ratio of non-white pixels in the back surface image data exceeds a predetermined ratio (step Sb3). In other words, the control unit 21 determines whether or not the document is a document that can cause show-through.

  If no image is formed on the back side of the document (step Sb3: NO), the control unit 21 supplies gradation data to the reflection unit 23 and changes the color of each pixel of the reflection unit 23 to white. (Step Sb5). On the other hand, when an image is formed on the back side of the document (step Sb3: YES), the control unit 21 supplies gradation data to the reflection unit 23, and the color of each pixel of the reflection unit 23 is a non-white color (for example, Black) (step Sb4). At this time, the reflection unit 23 may display a halftone that is neither white nor black.

  Subsequently, after the color of each pixel of the reflection unit 23 has changed, the control unit 21 causes the reading unit 22 to read the surface of the document (step Sb6). At this time, the reading unit 22 generates surface image data. And the control part 21 acquires surface image data from the reading part 22, and outputs it via the output part 26 (step Sb7).

  The reading operation of the reading device 20 is as described above. By operating in this way, the reading device 20 can read an image under conditions according to the image on the back side of the document. For example, when it is determined that no image is formed on the back side of the document, the reading device 20 reads the surface of the document with the color of each pixel of the reflection unit 23 set to white. Therefore, in this case, surface image data with high contrast can be obtained. If it is determined that an image is formed on the back side of the document, the reading device 20 reads the surface of the document with the color of each pixel of the reflection unit 23 set to a non-white color. Therefore, in this case, surface image data in which show-through is suppressed can be obtained.

[Third Embodiment]
Subsequently, a third embodiment of the present invention will be described. In this embodiment, the present invention is applied to a flatbed scanner, and the configuration thereof is almost the same as that of the reading device 10 described above. However, in this embodiment, the reading operation for generating image data is different from that in the first embodiment. Therefore, in the present embodiment, the description will focus on the parts that are different from the first embodiment. In addition, about the part which has the structure similar to the reader 10, the code | symbol same as the reader 10 is used, and the description is abbreviate | omitted suitably.

FIG. 11 is a block diagram illustrating the overall configuration of the reading device 30 according to the present embodiment. The reading device 30 includes a control unit 31, a reading unit 12, an output unit 13, and an operation unit 14.
In addition to the same function as the control unit 11, the control unit 31 has a function of generating a single image data by combining a plurality of image data. The control unit 31 performs processing for generating two pieces of image data by changing the color of the reflective layer 125b for the same document, and generating one piece of image data based on the two pieces of image data.

FIG. 12 is a flowchart illustrating a reading operation of the reading device 30 according to the present embodiment. As shown in the figure, first, the control unit 31 supplies gradation data to the document pressing unit 125, and changes the color of each pixel of the reflective layer 125b to a color other than white (step Sc1). The color of the reflective layer 125b at this time may be black, but it is more desirable that it is a halftone that can be distinguished from the color of the document. This is because the contrast of the image data generated at this time is not lowered more than necessary.
When the gradation data is supplied, the control unit 31 instructs the motor 124 to move the carriage 12d and causes the document to be read (step Sc2). At this time, the reading unit 12 generates image data representing the document. The image data generated at this time is hereinafter referred to as “first image data”.

  Next, the control unit 31 acquires the first image data generated by the reading unit 12, and detects the edge of the document from the first image data (step Sc3). The control unit 31 specifies the edge of the document based on the gradation difference of the first image data. Moreover, the control part 31 memorize | stores temporarily the position (coordinate) of the edge part specified at this time.

FIG. 13 is a diagram illustrating an example of the first image data. When the size of the document is smaller than the document table 12c, the image data includes an image other than the document, as shown in FIG. The image other than the document is an image representing the reflective layer 125b. As described above, since the reflective layer 125b is designated with a color other than white, a gradation difference occurs at the boundary between the image representing the original and the image representing the reflective layer 125b. The control unit 31 specifies a portion where such a gradation difference occurs in both the main scanning direction and the sub-scanning direction, and detects both ends of the document. Note that when performing this detection, the control unit 31 preferably stores in advance the color of the reflective layer 125b in the first image data. In this way, it is possible to detect the end more easily.
Hereinafter, an area outside the specified end portion of the first image data is referred to as a “frame area”, and an inner area is referred to as a “document area”. Note that when the entire surface of the image data represents a document, there is no frame area and the edge of the document is not specified.

  Subsequently, the control unit 31 supplies gradation data to the document pressing unit 125, and changes the color of each pixel of the reflective layer 125b to white (step Sc4). Thereafter, the control unit 31 instructs the motor 124 to move the carriage 12d to read the document, and causes the reading unit 12 to generate image data representing the document (step Sc5). The image data generated at this time is hereinafter referred to as “second image data”.

  Next, the control unit 31 acquires the second image data generated by the reading unit 12, and analyzes the image represented by the second image data (step Sc6). The analysis performed by the control unit 31 at this time is the same as the analysis in step Sa3 described above. That is, the control unit 31 performs analysis for classifying the region represented by the second image data into any one of “background region”, “image region”, and “show-through region”.

After this analysis, the control unit 31 performs a process of combining the first image data and the second image data (Step Sc7). The image data obtained by this synthesis process is hereinafter referred to as “composite image data”.
FIG. 14 is a flowchart showing the synthesis process. As shown in the figure, the control unit 31 determines whether or not a frame area exists in the first image data (step Sc71). This determination is made based on whether or not the control unit 31 has detected an end in step Sc3, that is, whether or not the position of the end is stored. When a frame area exists in the first image data (step Sc71: YES), the control unit 31 deletes an area corresponding to the frame area from the second image data (step Sc72). That is, at this time, the control unit 31 performs a process of reducing the size (area) of the second image data. Note that, when the frame area does not exist in the first image data (step Sc71: NO), the control unit 31 performs the next process without performing the process of step Sc72.

  Next, the control unit 31 determines whether or not a show-through area exists in the second image data (step Sc73). The control unit 31 makes this determination based on the analysis result of step Sc6. Here, when the show-through area exists in the second image data (step Sc73: YES), the control unit 31 sets the gradation value of the area corresponding to the show-through area in the second image data to the same value in the first image data. Replacement with the gradation value of the position (step Sc74). Specifically, the control unit 31 specifies the position of the show-through area using the second image data, specifies the area corresponding to the position from the first image data, and extracts the gradation value of the area. To do. Then, the control unit 31 replaces each gradation value extracted from the first image data with the gradation value at the same position in the second image data. In this case, the control unit 31 may perform correction for increasing the contrast of the extracted gradation value. This is because the first image data tends to have a lower contrast than the second image data. If the show-through area does not exist in the second image data (step Sc73: NO), the control unit 31 ends the synthesis process without performing the process of step Sc74.

  The control unit 31 generates composite image data by a composite process. In other words, the control unit 31 converts the second image data into composite image data by the composite process. When the synthesized image data is obtained by the synthesis process, the control unit 31 outputs this via the output unit 13 (step Sc8).

  The reading operation of the reading device 30 is as described above. By operating in this way, the reading device 30 can output image data in which show-through is suppressed. Further, the reading device 30 can output image data that does not include an image other than the original (an image corresponding to the frame area) even when the original is smaller than the original table 12c. The trimming function (frame erasing function) provided in the scanner is generally one that deletes an area in a direction parallel to the main scanning direction or the sub-scanning direction. However, according to the reading device 30 of this embodiment, the document Can be detected with high accuracy even when the sheet is placed obliquely with respect to the document table 12c.

[Modification]
In the above, the present invention has been described by exemplifying the first to third embodiments. However, the present invention is not limited to the embodiment described above, and can be implemented in various other forms. Therefore, here, an example of another embodiment will be described.

  The contents described in the first and third embodiments may be implemented by a sheet feed type scanner. For example, if a mechanism for reading the same sheet twice is provided, the present invention can be applied to a sheet feed type scanner. In the second embodiment, the means for reading the front and back of the document is provided, but the front and back of the document may be read by a single sensor. For example, if a mechanism is provided that allows the same path to be conveyed by reversing the front and back sides of the paper, it is possible to generate front surface image data and back surface image data with a single sensor.

In the second embodiment, a plurality of document transport modes are conceivable. For example, when a sufficient interval between the reading unit 22 and the back surface detection unit 24 can be secured, the reading operation shown in FIG. 10 can be performed while the document is conveyed at a constant speed. On the other hand, if the distance between the reading unit 22 and the back surface detection unit 24 cannot be sufficiently ensured, after the back surface image data is generated by the back surface detection unit 24, the conveyance of the document is temporarily stopped and the floor of the reflection unit 23 is stopped. The document conveyance may be resumed after the adjustment control is completed. Alternatively, when the distance between the reading unit 22 and the back surface detection unit 24 is less than the length of the document, the back surface image data is generated by the back surface detection unit 24 and then the document is transported in the opposite direction to that before the reflection unit. Alternatively, the reading unit 22 may read the data after the gradation control of 23 is completed.
In the second embodiment, the document may be divided into a plurality of areas in the sub-scanning direction, and gradation control may be performed for each of the divided areas.

  In the first embodiment, when the show-through area exceeds a predetermined ratio, reading may be performed under conditions different from the case where the color of the reflective layer 125b is white. For example, when the show-through area exceeds a predetermined ratio, the amount of received light per unit area of the image sensor array 123 may be increased or the amount of received light per unit time may be further increased. In such a case, the control unit 11 may delay the document conveyance time so that the exposure time in the image sensor array 123 becomes longer. If the light amount of the light source 121 can be adjusted, the control unit 11 increases the light amount. May be.

  In the first embodiment, reading is performed in a state where the reflective layer 125b is white, or reading is performed in a state where the reflective layer 125b has a lower reflectance than white. It is good also as a mode. For example, a first operation mode for suppressing show-through and a second operation mode for reading with high contrast are provided. In the second operation mode, the reflectance of the reflective layer 125b is the first operation mode. You may control so that it may become higher than a mode. Of course, in this case, three or more kinds of operation modes in which the gradation of the reflective layer 125b is different in stages may be provided.

  Further, the gradation of each pixel of the reflective layer 125b and the reflective portion 23 may be changed according to the image on the back side of the opposing document. For example, when there is a region where the show-through may occur on the back side of the document and a region where it does not occur, the pixels in the region facing the former may be black, and the pixels in the region facing the latter may be white. In the second embodiment, when such an operation is performed, the gradation of the reflection unit 23 may be changed according to the conveyance of the document.

Further, the display body used for the reflective layer 125b and the reflective portion 23 may be other than the memory liquid crystal. For example, a microcapsule electrophoretic display used in so-called electronic paper, that is, an EPD (ElectroPhoretic Display) may be used.
Since EPD can be flexible, the display surface can be bent to some extent when it is used. Further, the liquid crystal display body may change gradation when a local pressure is applied, but EPD does not cause such gradation change (so-called indentation). Therefore, EPD is particularly suitable for use as the flatbed reflective layer 125b. This is because a flatbed scanner may read a thick original such as a book with a non-uniform thickness. When reading such a document, a certain amount of pressing is required to bring the document and the reflective layer 125b into close contact with each other, and the reflective layer 125b easily deforms together with the elastic layer 125a depending on the shape of the document. It can be said that the display body which has the property and does not generate indentation is particularly desirable.

  In the first and second embodiments, the display body used for the reflective layer 125b and the reflective unit 23 may be configured not to have a plurality of pixels in the main scanning direction or the sub-scanning direction. For example, when it is sufficient that the entire display surface exhibits a single gradation, it is not necessary to have a plurality of pixels. Further, a configuration in which a plurality of strip-shaped display bodies each exhibiting a specified gradation are arranged may be employed.

  In the first and third embodiments, the document pressing unit 125 may be configured to apply a driving voltage to the reflective layer 125b so as to follow the movement of the carriage 12d. This means that the driving unit of the document pressing unit 125 applies the driving voltage in order from the pixel on the near side with respect to the moving direction of the carriage 12d, and the control unit 11 (31) is in this order. It is to specify the gradation with. In this way, it is possible to start reading a document even if gradation control has not been completed for the entire surface of the reflective layer 125b. Therefore, such a configuration can be said to be particularly suitable when a display body that requires time for gradation control of each pixel is used.

  Further, the configuration of the image sensor can be modified. For example, in a flatbed scanner, a two-dimensional sensor, that is, an area sensor that simultaneously reads the entire surface of a document at one time can be used in addition to the configuration in which the image sensor array, that is, the line sensor is moved. In this way, it is possible to shorten the time required for reading. Of course, an area sensor that reads the entire surface of the document multiple times may be used.

The present invention can also be applied to an image forming apparatus such as a copying machine.
FIG. 15 is a diagram illustrating a copying apparatus 90 according to the present invention. The copying apparatus 90 includes a reading unit 91 at the top and an image forming unit 92 at the bottom. The reading unit 91 has a configuration similar to that of the reading device of the first or third embodiment, and generates image data in which show-through is suppressed. In the figure, the hatched portion corresponds to the reflective layer 125b described above. The image forming unit 92 forms an image corresponding to the image data generated by the reading unit 91 on a sheet-like material (copy paper or the like). The image forming unit 92 may be, for example, an ink jet method or an electrophotographic method. According to such a copying apparatus 90, show-through can be suppressed even in hard copy of a document.

It is a block diagram which shows the whole structure of a reader. It is a figure which shows the structure of a reading part. It is a figure which shows the structure of a document press part. It is a flowchart which shows the reading operation | movement by a reader. It is a histogram figure which illustrates the analysis result of image data. It is a schematic diagram for demonstrating the effect | action by a reader. It is a schematic diagram for demonstrating the effect | action by a reader. 2 is a block diagram illustrating an overall configuration of a reading device 20. FIG. It is a figure which shows the structure of a reading part, a reflection part, a back surface detection part, and a document conveyance part. It is a flowchart which shows the reading operation | movement by a reader. It is a block diagram which shows the whole structure of a reader. It is a flowchart which shows the reading operation | movement of a reader. It is a figure which shows an example of 1st image data. It is a flowchart which shows a synthetic | combination process. 1 is a diagram illustrating a copying apparatus 90 according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 20, 30 ... Reading apparatus 11, 21, 31 ... Control part, 12, 22 ... Reading part, 13, 26 ... Output part, 14, 27 ... Operation part, 23 ... Reflection part, 24 ... Back surface detection part, 25: Document conveying section, 125 ... Document pressing section

Claims (14)

Irradiating means for irradiating light on the sheet-like material on which the image is formed;
Light transmitted through the sheet-like material out of the light irradiated by the irradiating means is arranged so as to face the surface opposite to the surface irradiated with light by the irradiating means of the sheet-like material. Reflecting means for reflecting in the same direction as the reflected light received by the generating means at a degree according to the specified gradation;
Gradation control means for designating gradation to the reflection means;
A reading apparatus comprising: a generation unit configured to receive reflected light of the light irradiated by the irradiation unit on the sheet-like material and generate image data corresponding to the amount of received light.   The reading apparatus according to claim 1, wherein the reflection unit exhibits a gradation specified by the gradation control unit. Comprising detection means for detecting show-through occurring in the sheet-like material,
The gradation control means includes
The reading apparatus according to claim 1, wherein a gradation corresponding to a result of detection of show-through by the detection unit is specified for the reflection unit. A conveying means for conveying the sheet-like material;
The irradiation means includes
2. The reading apparatus according to claim 1, wherein light is irradiated to a sheet-like object that is conveyed by the conveying unit and in which show-through is detected by the detecting unit. A moving means for moving the irradiation means so that the entire surface of the sheet-like material is irradiated with light;
The reading apparatus according to claim 1, wherein the reflection unit has an area facing the entire surface of the sheet-like material. The reflecting means is
A plurality of reflecting portions exhibiting a gradation specified by the gradation control means in a moving direction of the moving means;
The gradation control means includes
The reading apparatus according to claim 5, wherein gradations are specified in order in the movement direction with respect to the plurality of reflection units. The reflecting means is
A plurality of reflecting portions exhibiting a gradation specified by the gradation control means are provided in a predetermined direction,
The detection means includes
For the predetermined direction, a show-through occurring in the sheet-like material and both ends of the sheet-like material are detected,
The gradation control means includes
In the case where the irradiating means irradiates light, when the reflecting portion exists outside both ends of the sheet-like object detected by the detecting means, the degree to which the reflecting portion reflects the transmitted light is determined by the sheet. 3. The reading according to claim 2, wherein gradation is specified for each of the plurality of reflection units such that a reflection unit that does not exist outside both ends of the object is higher than the degree of reflection of the transmitted light. apparatus. The gradation control means includes
The control is performed by a first mode in which the transmitted light is reflected at a first degree and a second mode in which the transmitted light is reflected at a second degree higher than the first degree. Item 2. The reading device according to Item 1. The generating means includes
For the same sheet-like material, when the gradation control unit performs control in the first mode, first image data is generated, and the gradation control unit performs control in the second mode. If so, generate second image data,
The reading apparatus according to claim 8, further comprising a combining unit that generates one combined image data from the first and second image data. The generating means comprises an image sensor;
The exposure amount of the image sensor when the gradation control unit reflects the transmitted light at a first degree, and the gradation control unit reflects the transmitted light at a second degree higher than the first degree. The reading apparatus according to claim 1, further comprising an exposure control unit configured to increase an exposure amount when the exposure is performed.   The reading apparatus according to claim 1, wherein the reflection unit includes a reflection unit using a memory liquid crystal.   The reading device according to claim 1, wherein the reflecting means includes a reflecting portion having flexibility.   The reading device according to claim 12, wherein the reflection unit exhibits a gradation by an electrophoresis method. A reading device according to claim 1;
An image forming means for forming an image according to the image data generated by the generating means.

Images