JP2005045462A - Document reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a document reading apparatus capable of surely detecting abnormality of image data caused by dust and dirt existing at a read position. <P>SOLUTION: A flowchart for explaining operation procedures of the document reading apparatus includes: a step S1 of first reading an image at a reading position when the reading operation is started and entering its image data to a control section; and steps S2, S3 and S4 in this order of then sequentially reading a tip region, a main region and a tail end region of a read face of a document and entering their image data to the control section, and processing a group of pixels located at the same position in the main scanning direction and whose width and density are the same as each other as abnormity pixels when the group of pixels are consecutive in the subscanning direction in all the regions. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an original reading apparatus that reads an image of an original, and more particularly to a sheet-through type original reading apparatus.
[0002]
[Prior art]
Some image forming apparatuses include a so-called sheet-through type document reading device that can read an image at a reading position while moving a document set on a document tray one by one. .
In a sheet-through type document reading device, when an image of a document is read with dust or paper dust adhering to the reading position, the dust or paper dust is continuously read as pixels, and as a result, image data Black streaks and white streaks are generated. If this is, for example, a facsimile machine, the read image data is output at the receiver, so there is little detection of image data abnormalities at the transmission source, and image data containing black or white stripes is transmitted. Will continue.
[0003]
In order to solve such a problem, a document reading apparatus that detects dust at a reading position and corrects an abnormality in image data caused by the dust is provided as a conventional technique (see Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-262083
[Problems to be solved by the invention]
However, when there is a ruled line in the sub-scanning direction over one page, such as graph paper, if the ruled line is included in the correction area, the ruled line is erroneously removed.
The present invention has been made based on such a background, and an object of the present invention is to provide a document reading apparatus capable of reliably detecting an abnormality in image data caused by dust or dirt present at a reading position.
[0006]
[Means for Solving the Problems and Effects of the Invention]
In order to achieve the above object, the invention according to claim 1 is characterized in that the document passes in the reading position (4) extending in the main scanning direction and the sub-scanning direction orthogonal to the main scanning direction of the reading position. Document feeding means (5, 6) for moving the document and the document passing through the reading position are read as line data in the main scanning direction, and the contents from the leading edge to the trailing edge of the document passing through the plurality of line data (13 ) And the plurality of line data extending in the main scanning direction when the same density pixel exists continuously in the sub-scanning direction, the density pixel is detected as an abnormal pixel. An abnormal pixel detecting means (7), wherein the abnormal pixel detecting means reads the reading position in the main scanning direction without passing the original through the reading position. Duplicate Line data (12), a plurality of line data (131, 132) obtained by reading the leading edge and trailing edge of the document passing through the reading position in the main scanning direction, and the leading edge of the document passing through the reading position And a plurality of line data (133) obtained by reading a portion other than the rear end portion in the main scanning direction, a plurality of line data at the reading position and a plurality of line data at the front end portion and the rear end portion of the document. And a plurality of line data other than the leading edge and the trailing edge of the document, when the same density pixel exists continuously in the sub-scanning direction, the density pixel is detected as an abnormal pixel. An original reading apparatus including line data comparing means (8).
[0007]
The alphanumeric characters in parentheses indicate corresponding components in the embodiments described later. The same applies hereinafter.
According to this configuration, the line data obtained by reading the reading position in a state where the original does not pass through the reading position, the line data obtained by reading the leading end portion and the rear end portion of the original passing through the reading position, and the reading position are passed. In all of the line data obtained by reading the portions other than the leading edge and trailing edge of the original to be detected, when the same density pixel exists in the sub-scanning direction, it is detected as an abnormal pixel, so that the abnormal pixel is reliably detected. Even when a ruled line exists in the sub-scanning direction over one page of the document, it is possible to prevent the ruled line in the document from being erroneously detected as an abnormal pixel caused by the influence of dirt or the like at the reading position. Can do.
[0008]
Further, it is possible to prevent erroneous detection of abnormal pixels when dust is present at the reading position and the document is moved to the reading position and the dust is accidentally removed.
The invention according to claim 2 is characterized in that the abnormal pixel detecting means (7) is used for detecting abnormal pixels when the reading position is read in a state where a document does not pass through the reading position (4). The threshold used for detecting abnormal pixels when the leading edge and the trailing edge of the document passing through the reading position are read, and the case where a portion other than the leading edge and the trailing edge of the document passing through the reading position is scanned The document reading apparatus (1) according to claim 1, further comprising a threshold individual changing means (7) capable of individually changing a threshold used for detecting an abnormal pixel.
[0009]
According to this configuration, the threshold value used for detecting the abnormal pixel is determined when the reading position is read in a state where the original does not pass through the reading position, and when the leading edge and the trailing edge of the original passing through the reading position are detected. Can be individually changed between when the document is read and when the portion other than the leading edge and the trailing edge of the document that passes through the reading position is read. It is possible to detect an abnormal pixel corresponding to a change in read information.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic sectional view showing the configuration of a facsimile machine to which a document reading apparatus 1 according to an embodiment of the present invention is applied. The image data of the document read by the document reading device 1 is transmitted to a reception destination designated in advance as data for facsimile transmission.
[0011]
The document reader 1 includes a light source 210 for irradiating light toward the document, a CCD licensor 220 for detecting reflected light from the document and converting it into an electrical signal, and further reflecting reflected light from the document. Thus, first, second, and third reflecting mirrors 231, 232, and 233 are provided for guiding to the detection surface of the CCD licensor 220. The light source 210, the CCD licensor 220, the first reflecting mirror 231, the second reflecting mirror 232, and the third reflecting mirror 233 constitute an image reading unit 2 for reading an image of a document. A transparent contact glass 3 is disposed above the image reading unit 2. A reading position 4 extending in the main scanning direction is formed on the upper surface of the contact glass 3.
[0012]
One or a plurality of documents set on a document tray (not shown) is passed through a document transport path 6 via a registration roller 5 and moved on the reading position 4 with the reading surface facing downward.
The irradiation light emitted from the light source 210 toward the document is reflected by the reading surface of the document. The reflected light from the document is sequentially reflected by the first reflecting mirror 231, the second reflecting mirror 232, and the third reflecting mirror 233, and enters the detection surface of the CCD licensor 220. The main scanning of the original in the image reading unit 2 is achieved by electrical scanning in the CCD licensor 220, and the original is sub-scanned by passing the original over the reading position 4 with the reading surface facing downward. The Since the light source 210 always illuminates the reading position 4, if the reading position 4 is dirty, the light is always lit, and the image data includes abnormal pixels that are black or white stripes.
[0013]
The document reading apparatus 1 includes the image reading unit 2, the control unit 7, the image processing unit 8, the operation unit 9, the display unit 10, and the image transmission unit 11. When the operation unit 9 is operated by the operator, the image reading unit 2 reads the reading surface of the document as described above.
The electrical signal output from the CCD licensor 220 is input as image data to the control unit 7 via an A / D converter (not shown). The image data input to the control unit 7 is further subjected to predetermined processing (described later) by the image processing unit 8 and transmitted to an external receiving destination via the image transmission unit 11.
[0014]
FIG. 2 is a conceptual diagram illustrating an example of image data input to the control unit 7. When a document passing over the reading position 4 is read by the image reading unit 2, the reading position 4 is read for a predetermined time in a state where the document does not exist on the reading position 4 prior to reading the document. The read data at the read position 4 is referred to as read position data 12. Subsequently, the document is passed over the reading position 4, and the document is read by the image reading unit 2. The read data of the original is referred to as original data 13. The reading position data 12 and the document data 13 are input to the control unit 7.
[0015]
The document data 13 further includes leading edge region data 131 that is data of the leading edge region in the sub-scanning direction of the document, trailing edge region data 132 that is data of the trailing edge region in the sub-scanning direction of the document, and leading edge region and trailing edge of the document. It is divided into main area data 133 which is data of the main area other than the end area. The leading edge area data 131 and the trailing edge area data 132 are, for example, read data of an area of about 2 to 3 mm from the leading edge and the trailing edge in the sub-scanning direction of the document, respectively. No image is formed on the.
[0016]
It is assumed that the reading operation is performed in a state where dirt is present on the reading position 4. In the reading position data 12, pixel groups 14, 15, 16, 17, and 18 having the same density appear at positions in the main scanning direction corresponding to the dirt positions.
In the original data 13, pixel groups 19, 20, 21, 22, 23 having the same density extending in the sub-scanning direction appear at the same position in the main scanning direction. These pixel groups 19, 20, 21, 22, and 23 exist at the same positions as the pixel groups 14, 15, 16, 17, and 18 that appear in the reading position data 12 in the main scanning direction.
[0017]
Incidentally, the pixel groups 19 and 20 exist only in the main area data 133, the pixel group 21 exists over the main area data 133 and the rear end area data 132, and the pixel groups 22 and 23 correspond to the front end area data 131. It exists between the main area data 133 and the trailing edge area data 132 (from the leading edge to the trailing edge of the document data 13 in the sub-scanning direction). The pixel groups 19, 21, and 23 have the same width (length in the main scanning direction) as the pixel groups 14, 16, and 18, and the pixel groups 20 and 22 are larger than the widths of the pixel groups 15 and 17, respectively. Is also getting thinner.
[0018]
In the above case, how to determine which is a pixel group based on dirt and which is not is described with reference to a flowchart of FIG. 3 together with a specific operation procedure. When the document is set on the document tray and the operation unit 9 is operated by the operator, the reading position 4 immediately before the document passes over the reading position 4 is read by the image reading unit 2, and the reading position data 12 is controlled. Input to the unit 7 (step S1). Subsequently, the front end area, the main area, and the rear end area of the document are sequentially read, and the front end area data 131, the main area data 133, and the rear end area data 132 are input to the control unit 7 (Step S1). S2->S3-> S4). The reading position data 12, the front end area data 131, the main area data 133, and the rear end area data 132 input to the control unit 7 are sent to the image processing unit 8, and the image processing unit 8 compares each data. Is performed (step S5).
[0019]
A pixel group that exists at the same position in the main scanning direction and has the same width and density is included in all of the reading position data 12, the front end area data 131, the main area data 133, and the rear end area data 132. When the pixels are continuous in the sub-scanning direction, the pixel group is processed as an abnormal pixel. The abnormal pixel processing in the image processing unit 8 is performed, for example, by replacing the pixel group with a pixel adjacent in the main scanning direction.
[0020]
Specifically, when comparing the pixel group 14 and the pixel group 19, the pixel group 14 and the pixel group 19 exist at the same position in the main scanning direction, but the pixel group 19 exists only in the main area data 133. Therefore, it can be said that there is a high possibility that the pixel group 19 is a pixel obtained by reading a ruled line or the like described on the document. Therefore, the pixel group 19 is not processed as an abnormal pixel. Similarly, in the comparison between the pixel group 15 and the pixel group 20, the pixel group 20 exists only in the main area data 133. Therefore, the pixel group 20 is a pixel obtained by reading a ruled line or the like described in the document. It is highly possible. Therefore, the pixel group 20 is not processed as an abnormal pixel.
[0021]
Comparing the pixel group 16 and the pixel group 21, the pixel group 16 and the pixel group 21 exist at the same position in the main scanning direction, but the pixel group 21 does not exist in the tip region data 131. 21 cannot be determined to be a pixel from which the dirt at the reading position 4 has been read. Therefore, the pixel group 21 is not processed as an abnormal pixel.
Further, when comparing the pixel group 17 and the pixel group 22, the pixel group 17 and the pixel group 22 exist at the same position in the main scanning direction, and the pixel group 22 further includes the tip region data 131 and the main region data 133. And the trailing edge area data 132 (from the leading edge to the trailing edge of the document data 13 in the sub-scanning direction). However, since the widths of the pixel group 17 and the pixel group 22 are different, in this case as well, the pixel group 22 cannot be determined to be a pixel from which the stain at the reading position 4 has been read, and is replaced with a pixel adjacent in the main scanning direction. If this happens, pixels may be lost. Therefore, the pixel group 22 is not processed as an abnormal pixel.
[0022]
Comparing the pixel group 18 and the pixel group 23, the pixel group 18 and the pixel group 23 exist at the same position in the main scanning direction, and the pixel group 23 includes the front end area data 131, the main area data 133, and the rear end area. It exists over the data 132 (from the leading edge to the trailing edge of the document data 13 in the sub-scanning direction). Furthermore, since the widths of the pixel group 18 and the pixel group 23 are the same, it can be determined that the pixel group 23 is a pixel from which the stain at the reading position 4 has been read. Therefore, the pixel group 23 is processed as an abnormal pixel.
[0023]
For example, if the data processing is performed based only on the information of the reading position data 12 as in the prior art, all of the data 19 to 23 are to be processed.
In the document data 13, only the pixel group 23 is regarded as an abnormal pixel (YES in step S6) and replaced with a pixel adjacent in the main scanning direction (step S7). The document data 13 processed by the image processing unit 8 is transmitted to an external reception destination via the image transmission unit 11. At this time, the data 23 is not output to the receiving paper. As a result, only the pixel from which the stain at the reading position 4 is read can be reliably processed as an abnormal pixel. For example, even if a ruled line exists in the sub-scanning direction over one page of the document, The read pixel is not erroneously processed as an abnormal pixel.
[0024]
In addition, the density threshold used when detecting abnormal pixels in the reading position data 12, the front end area data 131, the main area data 133, and the rear end area data 132 is individually changed by operating the operation unit 9. It may be configured to. This density threshold value is input to the control unit 7, and it is determined whether or not the pixel is abnormal based on this density threshold value. Thereby, it is possible to detect an abnormal pixel corresponding to the difference in the degree of compression at the reading position of the document, which is caused by the document being bent.
[0025]
In this embodiment, the configuration in which the document reading apparatus 1 is applied to a facsimile apparatus has been described. However, the document reading apparatus 1 is not limited to the application to a facsimile apparatus, and is applied to, for example, a digital copying machine or a scanner apparatus. It may be a configuration.
The present invention is not limited to the embodiment described above, and various modifications can be made within the scope of the claims.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a configuration of a facsimile machine to which a document reading apparatus according to an embodiment of the present invention is applied.
FIG. 2 is a conceptual diagram illustrating an example of image data. FIG. 3 is a flowchart illustrating an operation procedure of the document reading apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Document reading apparatus 2 Image reading part 4 Reading position 5 Registration roller 6 Original conveyance path 7 Control part 8 Image processing part 12 Reading position data 13 Original data 131 Front end area data 132 Rear end area data 133 Main area data

Claims (2)

A reading position extending in the main scanning direction;
Document feeding means for moving the document so that the document passes in the sub-scanning direction perpendicular to the main scanning direction of the reading position;
A document reading means for reading the document passing through the reading position as line data in the main scanning direction and outputting the contents from the leading end to the trailing end of the passing document as a plurality of line data;
In the plurality of line data extending in the main scanning direction, when the same density pixel exists continuously in the sub-scanning direction, the original reading apparatus includes an abnormal pixel detection unit that detects the density pixel as an abnormal pixel. There,
The abnormal pixel detecting means includes a plurality of line data obtained by reading the reading position in the main scanning direction in a state where the document does not pass through the reading position, and a leading end portion and a trailing end portion of the document passing through the reading position. The plurality of line data read in the main scanning direction is compared with the plurality of line data read in the main scanning direction at portions other than the leading edge and the trailing edge of the document passing through the reading position. All of the line data, the plurality of line data of the leading edge and the trailing edge of the document, and the plurality of line data of the portion other than the leading edge and the trailing edge of the document, continuously in the sub-scanning direction. An original reading apparatus comprising line data comparing means for detecting, when there is an identical density pixel, that density pixel as an abnormal pixel. The abnormal pixel detecting means includes a threshold value used for detecting abnormal pixels when the reading position is read in a state where the original does not pass through the reading position, and a leading end portion and a trailing end portion of the original passing through the reading position. The threshold used for detecting abnormal pixels when reading the image and the threshold used for detecting abnormal pixels when reading a portion other than the leading edge and the trailing edge of the document passing through the reading position are individually changed. The document reading apparatus according to claim 1, further comprising a threshold value individual changing unit capable of changing the threshold value.

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