JP2018195960A - Reader - Google Patents

Abstract

A reading apparatus for accurately estimating the type of document is provided.
A reading apparatus that reads a document sandwiched between a background plate and a table, and includes an estimation unit that estimates a type of the document based on a pixel value of a shadow of the document generated on the background plate. The estimation unit estimates the type of the document based on the pixel value of the darkest part among the pixel values of the shadow. The estimation unit estimates the thickness of the document as the type of the document. The reading device includes a storage unit that stores a correspondence relationship between the shadow darkness and the thickness of the document, and the estimation unit estimates the thickness of the document based on the pixel value of the shadow and the correspondence relationship. .
[Selection] Figure 3

Description

  The present invention relates to a reader.

The scanner optically reads a document transported to the table or placed on the table.
Here, a thickness detection device that calculates the thickness of the print medium by a predetermined calculation process based on the moving amount of the image pickup unit, the length of the shadow of the print medium, and the distance from the print medium placement surface to the lower surface of the image pickup unit Is disclosed (see Patent Document 1).

JP 2009-256000 A

  In the method of detecting the thickness of the print medium based on the length of the shadow of the print medium as in the above-mentioned document 1, the shadow length is stable depending on the posture (for example, floating or distortion of the medium) and the state of the print medium. Therefore, there is a problem that the thickness cannot be accurately detected.

  The present invention has been made in view of the above-described problems, and provides a reading apparatus that contributes to accurate estimation of a document.

One aspect of the present invention is a reading apparatus that reads a document sandwiched between a background plate and a table, and estimates the type of the document based on a pixel value of a shadow of the document generated on the background plate. An estimation unit is provided.
According to this configuration, since the reading apparatus estimates the type of the document based on the pixel value of the shadow of the document generated on the background plate, the estimation result is stable and the type of the document can be accurately estimated.

In one aspect of the present invention, the estimation unit may estimate the type of the document based on a darkest pixel value among the shadow pixel values.
According to this configuration, since the reading apparatus estimates the type of the original based on the pixel value of the darkest part of the shadow of the original generated on the background plate, it is easy to obtain a stable estimation result.

In one aspect of the present invention, the estimation unit may estimate the thickness of the document as the type of the document.
According to this configuration, the thickness of the document is estimated based on the pixel value of the shadow of the document generated on the background plate.

According to one aspect of the present invention, the reading apparatus includes a storage unit that stores a correspondence relationship between the shadow darkness and the thickness of the document, and the estimation unit uses the shadow pixel value and the correspondence relationship. Based on this, the thickness of the original may be estimated.
According to this configuration, the reading apparatus can accurately estimate the thickness of the document according to the darkness (pixel value) of the shadow of the document generated on the background plate by referring to the correspondence relationship stored in advance. it can.

  The technical idea of the present invention can be realized in various modes other than the category of reading devices. For example, a method including a process executed by a reading device, a program that causes a hardware (computer) to execute the method, and a computer-readable storage medium that stores the program are also established as inventions.

FIG. 3 is a diagram simply illustrating a configuration of a reading device. The figure which shows simply a part in the housing | casing of a reader. 6 is a flowchart showing a document type estimation process. The figure which shows the reading result of several types of original document with a graph. The figure which shows a manuscript type table.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Each figure is only an example for explaining this embodiment.
FIG. 1 simply shows a configuration of a reading apparatus 10 according to the present embodiment. The reading device 10 is a scanner capable of optically reading a document and storing a reading result (image data) or outputting the reading result to the outside. The reading device 10 is, for example, a document scanner that can continuously read a plurality of documents one by one. Alternatively, the reading device 10 may be a product having both functions of a document scanner and a flat bed scanner capable of reading a document placed in a stationary state on a document table.

  The reading device 10 includes, for example, a control unit 11, a reading unit 12, a transport unit 13, a communication interface (IF) 14, a storage unit 15, and the like. The control unit 11 includes, for example, one or a plurality of ICs such as a CPU, a ROM, and a RAM. The control unit 11 controls the behavior of the entire reading device 10 through cooperation of the installed program and hardware. The storage unit 15 is a nonvolatile storage device. The storage unit 15 may be a part of the control unit 11.

  The transport unit 13 is a transport mechanism that transports a document placed on a document tray (not shown) along a predetermined transport path under the control of the control unit 11. Of course, the transport unit 13 may include an automatic document feeder (ADF) that transports a plurality of documents placed on the document tray one by one.

  The reading unit 12 is a unit for reading a document under the control of the control unit 11 and includes a light source, an optical system, an image sensor, and the like as is known. The light from this light source is reflected by the original and forms an image on the image sensor by the optical system. Then, the image sensor outputs a reading result according to the imaged light. The control unit 11 appropriately applies image processing and analysis to the reading result output from the image sensor, cuts out, and stores image data as the reading result in, for example, the storage unit 15 or communication. It can be transmitted to the outside through the IF 14.

The communication IF 14 is an IF that performs communication with the outside in a wired or wireless manner in accordance with a predetermined communication protocol including a known communication standard. For example, a PC (personal computer) is connected to the communication IF 14, and image data as a document reading result is transmitted to the PC via the communication IF 14. Although not shown, the reading device 10 appropriately includes known configurations such as a display unit for displaying visual information and an operation unit such as a touch panel and a physical button for receiving an operation from a user.
The reading device 10 may be a multifunction device that functions as a printer, a facsimile, or the like in addition to the scanner.

  FIG. 2 simply shows a part of the housing of the reading apparatus 10. The document P transported along the transport direction D by the transport unit 13 is transported between the opposed table 16 and the background plate 17. The table 16 is made of a transparent material such as glass. The reading unit 12 is disposed on the side opposite to the side on which the background plate 17 of the table 16 is present. The background plate 17 is a member of a predetermined color, for example, a gray color having a predetermined density, and is irradiated by a light source 12 a included in the reading unit 12. The reading unit 12 performs reading by receiving reflected light of the light emitted from the light source 12a (reflected light from the background plate 17 and the document P) by the image sensor 12b.

  The reading unit 12 includes a line sensor (12b) including a plurality of imaging elements (pixels) arranged in a direction orthogonal to the transport direction D (a direction perpendicular to the paper surface of FIG. 2), and performs one reading operation. To read one line image. The reading unit 12 obtains a two-dimensional reading result of the entire surface of the document P by repeating one line reading at a predetermined frequency. FIG. 2 shows a configuration for reading one side of the original P (the side facing downward in FIG. 2). Needless to say, the reading apparatus 10 faces the other side of the original P (upward in FIG. 2). The scanner may be capable of reading both sides simultaneously, having a configuration for reading (side).

Next, document type estimation processing executed by the control unit 11 will be described with reference to FIG.
FIG. 3 is a flowchart showing the estimation process. It can be said that the control part 11 functions as an estimation part of this invention by the point which performs the said estimation process.
The control unit 11 causes the reading unit 12 to start a reading operation at a predetermined timing (step S100). The predetermined timing is, for example, a predetermined timing at which the leading end of the document P does not reach the position of the reading unit 12 after the transport of the document P by the transport unit 13 is started.

  After step S100, the control unit 11 specifies the shadow pixel value of the document P based on the reading result of the document P sequentially transmitted from the reading unit 12 (step S110).

  FIG. 4 is a graph showing the results of reading a plurality of types of documents by the reading device 10. The graph is obtained in advance by each experiment in which a reading operation is started at the predetermined timing after the conveyance is started for each of a plurality of types of documents. In FIG. 4, the horizontal axis represents the time elapsed, the vertical axis represents the pixel value (tone value) as the read result, and the read result time for each of four different types of originals (original types A, B, C, and D). The corresponding change is shown. The used document types A, B, C, and D are all white paper and have different thicknesses. Specifically, the thickness of the document type A <the thickness of the document type B <the thickness of the document type C <the thickness of the document type D is established. Here, the pixel value is expressed in 256 gradations from 0 to 255, and the lower the gradation value, the darker the value. In FIG. 4, the reading result corresponding to the document type A is indicated by a solid line, the reading result corresponding to the document type B is indicated by a broken line, and the reading result corresponding to the document type C is indicated by a one-dot chain line. Are indicated by two-dot chain lines, respectively.

  It can be said that the scale on the horizontal axis (elapsed time) in FIG. 4 indicates each timing at which the reading unit 12 executes one reading operation. In addition, it can be said that the horizontal axis indirectly indicates a change in position in the conveyance direction D of the document conveyed by the conveyance unit 13. The reading result for each document type and each timing shown in FIG. 4 is obtained as a pixel value obtained by one specific pixel in the line sensor of the reading unit 12 (or an average value of pixel values obtained by a plurality of specific pixels). Applicable.

  According to FIG. 4, the reading results corresponding to the document types A, B, C, and D are initially values around the gradation values “110” to “140”, and the gradation is increased as the number of readings is increased. After the value “100” is cut, the value becomes lower (darker), and when the number of readings is repeated, the value increases (brightness increases) and greatly exceeds the gradation value “150”. ing. This is because, in the first few readings, when the document is not present, that is, when the background plate 17 is read and then the leading edge of the document approaches the position of the reading unit 12, the background is determined from the positional relationship between the light source and the document. This is because a shadow is generated on the plate 17 due to the leading edge of the document and the shadow is read, and then the leading edge of the document passes through the position of the reading unit 12 and the color (white) of the document is read. Referring to FIG. 2 in detail, in the process in which the document P is transported along the transport direction D, when the leading edge of the document P approaches the reading position by the image sensor 12b, the document P is moved in the transport direction D more than the image sensor 12b. A part of the light (see the broken line arrow in FIG. 2) irradiated by the upstream light source 12 a is blocked by the leading edge of the document P. As a result, a shadow due to the document P is generated in the range Q of the background plate 17 shown in FIG. 2, and the imaging element 12b receives the reflected light from the range Q, that is, reads the shadow of the document P.

  From FIG. 4, it can be understood that the shadow of the document generated on the background plate 17 is darker than the color of the background plate 17. FIG. 4 shows that there is a correlation between the thickness of the document and the darkness of the shadow of the document. According to FIG. 4, it can be seen that the shadow of the document generated on the background plate 17 becomes darker as the document thickness increases. It is presumed that the thicker the original is, the more difficult it is to transmit light through the original, and as a result, the shadow of the original generated on the background plate 17 becomes darker.

  Therefore, in step S110, the control unit 11 specifies the pixel value of the darkest part among the shadow pixel values of the document P. For example, based on the experimental result as described above, the control unit 11 causes the threshold value darker than the color reading result of the background plate 17 (see FIG. 4, for example, around the gradation value “100”). Value) is set. The control unit 11 obtains from the reading unit 12 after the start of step S100 until the reading result (pixel value) sequentially transmitted from the reading unit 12 falls below the threshold value and exceeds the threshold value. The lowest value in the read result is specified as the pixel value of the darkest part of the shadow of the document P.

  Next, the control unit 11 estimates the type of the document P based on the shadow pixel value of the document P specified in step S110 (step S120). As an example, it is assumed that a document type table 20 that defines the correspondence between pixel values of document shadows and document types is generated based on the above experimental results and stored in the storage unit 15 in advance. The document type table 20 can also be said to be a table that defines the correspondence between the darkness of the document shadow and the thickness of the document.

  FIG. 5 shows the document type table 20. The document type table 20 defines the correspondence between the pixel value of the darkest part of the shadow of the document, the document thickness, and the document type. It can be said that the thickness of the document expresses the difference between the documents, that is, the document type. Therefore, the control unit 11 estimates the type of the document P by reading out the document type and the document thickness corresponding to the pixel value of the shadow (darkest part) of the document P specified in step S110 from the document type table 20. For example, if the pixel value of the darkest part of the shadow of the document P specified in step S110 is the gradation value “31”, the control unit 11 refers to the document type table 20 in step S120, thereby performing step S100. It can be estimated that the document P that has started the reading operation is the document type A and the thickness = 0.297 mm.

  Even if the pixel value of the darkest part of the shadow of the document P identified in step S110 does not match any pixel value specified in the document type table 20, the control unit 11 performs, for example, the identified pixel value. The document type and the document thickness specified in the document type table 20 corresponding to the pixel value closest to can be used as the estimation result. Alternatively, the control unit 11 uses a plurality of document thicknesses corresponding to a plurality of pixel values close to the pixel value of the darkest part of the shadow of the document P specified in step S110 among the pixel values defined in the document type table 20. It is also possible to estimate the document thickness of the document P by the interpolation calculation. The control unit 11 executes step S120 and ends the document type estimation process.

The control unit 11 can use the result of the estimation process for various controls.
For example, when the transport unit 13 is controlled according to the thickness of the document P, the estimation result of the document P by the estimation process is used. More specifically, the control unit 11 changes the conveyance speed or the like of the document P by the conveyance unit 13 to an optimum speed according to the thickness of the document P estimated in step S120, thereby removing the scratches on the document P or the like. Can be prevented. For example, when the document P is thick, it tends to be stronger than when the document P is thin, and therefore the conveyance speed is set to be faster than when the document P is thin. Further, the control unit 11 may notify the user of the estimation result of the document P by displaying it on the display unit. Further, the control unit 11 may issue a warning to the user via the display unit or the like when the document type or thickness designated by the user in advance and the estimation result of the document P are different. Further, the control unit 11 switches the image processing method for the reading result (image data) acquired from the reading unit 12, various tables used for the image processing, and the like according to the estimated type of original P and original thickness. Can do.

  As described above, according to the present embodiment, in the reading apparatus 10 that reads the document P sandwiched between the background plate 17 and the table 16, the control unit (estimating unit) 11 causes the shadow of the document P generated on the background plate 17. The type of the document P is estimated based on the pixel value. According to this configuration, since the document type is estimated based on the pixel value of the shadow of the document generated on the background plate 17 having a correlation with the document type (particularly, the document thickness), the estimation result is stable, and the document type Can be estimated accurately. Further, it is possible to substantially detect the thickness of the document without separately requiring a sensor for detecting the thickness of the document. Since the control unit 11 estimates the type of the original P based on the pixel value of the darkest part among the pixel values of the shadow of the original P generated on the background plate 17, which has a high correlation with the original thickness, stable estimation is possible. The result is easy to obtain.

  It is not essential for the control unit 11 to refer to the document type table 20 when estimating the type of the document P based on the shadow pixel value of the document P identified in step S110 (step S120). For example, a specific function for calculating the document thickness corresponding to the shadow pixel value of the document P is stored in the storage unit 15 in advance, and the control unit 11 determines the shadow pixel value of the document P specified in step S110. And the function may be used to estimate (calculate) the thickness of the document P.

  The document type table 20 and the function are not stored in the storage unit 15 in the reading device 10 but are accessible via an external storage device (for example, the communication IF 14) with which the reading device 10 can communicate. (PC or server). Then, the control unit 11 may appropriately refer to the document type table 20 and the function stored in the external storage device at the timing of step S120.

The document type may be information on only the thickness of the document, or may include other information such as plain paper or photo paper in addition to the thickness of the document. When the document type includes other information, the control unit 11 allows the user to specify other information and responds to the pixel value of the shadow of the document from a plurality of document thicknesses that match the specified information. The document type may be specified.
Although the description has been made with respect to the scanner that transports the document, the type of the document may be estimated by applying to a method of moving the reading unit 12 without moving the document as in a so-called flatbed scanner.

DESCRIPTION OF SYMBOLS 10 ... Reading apparatus, 11 ... Control part (estimation part), 12 ... Reading part, 13 ... Conveyance part, 14 ... Communication IF, 15 ... Memory | storage part, 16 ... Stand, 17 ... Background board, P ... Original

Claims (4)

A reading device for reading a document sandwiched between a background plate and a table,
A reading apparatus comprising: an estimation unit configured to estimate a type of the document based on a pixel value of a shadow of the document generated on the background plate.   The reading apparatus according to claim 1, wherein the estimation unit estimates the type of the document based on a pixel value of a darkest portion among the pixel values of the shadow.   The reading apparatus according to claim 1, wherein the estimation unit estimates a thickness of the document as the type of the document. A storage unit storing the correspondence between the darkness of the shadow and the thickness of the document;
The reading apparatus according to claim 3, wherein the estimation unit estimates the thickness of the document based on the pixel value of the shadow and the correspondence relationship.

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