JP2007184714A - Image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader capable of detecting a degree of peeling off of a conductive coat due to wear of the conductive coat applied to an original platen glass and easily discriminating the lifetime or a replacement time of the original platen glass. <P>SOLUTION: The image reader is provided with: an original carrying belt 112 for carrying an original; the original platen glass 107 applied with the conductive coat in contact with the original carried by the original carrying belt 112; and an image sensor 106 for reading a white reference sheet via the original platen glass 107. Further, a control circuit 400 detects a degree of peeling-off of the conductive coat applied to the original platen glass 107 on the basis of an image of the reference sheet read by the image sensor 106. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image reading apparatus that reads an image of an original on a platen glass, and more particularly, to an image reading apparatus that detects a degree of peeling of a conductive coating applied to a platen glass.

  2. Description of the Related Art Conventionally, there has been an image reading apparatus that feeds a document to a document glass using a document feeder and reads an image of the document on the document glass (see, for example, Patent Document 1).

  When such a document feeder is used, dust and dirt are likely to adhere to the platen glass due to static electricity caused by friction between the fed document and the platen glass, or the document is electrostatically adsorbed to the platen glass. This causes a problem that the original is not fed normally.

As a means for solving the above-mentioned problems, there is one that performs antistatic treatment (conductive coating) on the surface of the platen glass (see, for example, Patent Document 2).
JP 2000-187362 A JP 2002-199188 A

  However, when the document feeder is used, the conductive coating is gradually peeled off due to friction between the document being fed and the platen glass, resulting in the original effect of preventing charging of the platen glass. There is a problem that it becomes impossible.

  Therefore, it is conceivable to replace the platen glass based on the usage time of the image reading apparatus or the number of originals to be read. However, the degree of peeling due to wear of the conductive coat varies depending on the use environment of the user. The replacement time could not be determined.

  The present invention has been made in view of the above problems, can detect the degree of peeling due to wear of the conductive coating applied to the platen glass, and easily determine the life or replacement time of the platen glass. An object of the present invention is to provide an image reading apparatus capable of performing the above.

  In order to achieve the above object, an image reading apparatus according to the present invention includes a document transport unit that transports a document, a document table glass that is in contact with the document transported by the document transport unit, and that is provided with a conductive coating. Based on the reading means for reading the white reference sheet through the platen glass and the image of the reference sheet read by the reading means, the degree of peeling of the conductive coat applied to the platen glass is detected. And a detecting means.

  The image reading apparatus according to the present invention includes a document transport unit that transports a document, a document transport unit glass that is in contact with the document transported by the document transport unit, and is provided with a conductive coating, and a document that is received by a user. A document placement unit glass that is not provided with a conductive coating, a reading unit that reads a white reference sheet through the document transport unit glass, and an image of the reference sheet that is read by the reading unit And detecting means for detecting the degree of peeling of the conductive coating applied to the original conveying section glass.

  According to the present invention, it is possible to detect the degree of peeling due to abrasion of the conductive coating applied to the platen glass, and it is possible to easily determine the life or replacement time of the platen glass.

  The best mode for carrying out the present invention will be described below with reference to the drawings. In the present embodiment, an image reading apparatus used in an image forming apparatus such as a copying machine will be described as an example of the image reading apparatus. However, the present invention is not limited to this.

  First, Example 1 will be described in detail below with reference to the drawings.

  FIG. 1 is a configuration example of an image reading apparatus using an image sensor such as a CCD. The image reading apparatus shown in FIG. 1 illuminates a document 108 on a platen glass 107 with a light source 101 for illuminating a document, and images a document image by a first mirror 102, a second mirror 103, a third mirror 104 and a lens 105. An image is formed on the light receiving surface of the sensor 106.

  In the image reading apparatus having this structure, the illumination lamp 101, the first mirror 102, the second mirror 103, and the fourth mirror 104 move in the sub-scanning direction S so that the document 108 can be read. Reference numeral 109 denotes a white plate for shading correction, and 110 denotes a cover glass that covers the white plate.

  Before reading the document 108 on the platen glass 107, the illumination lamp 101, the first mirror 102, the second mirror 103, and the fourth mirror 104 move below the white plate 109, and the image sensor 106 uses the white plate 109. Read. Based on the read value, the white level is corrected by performing shading correction by a signal processing circuit of FIG. 7 described later.

  FIG. 2 is an example of an image reading apparatus when a document feeder is installed in addition to FIG. In the present embodiment, an ADF (Auto Document Feeder) mounted on an image forming apparatus such as a copying machine is described as an example of a document feeder, but the present invention is not limited to this.

  As shown in the figure, the stacked originals are fed one by one onto the original platen glass 107 by the original conveying belt 112 rotated by the belt driving roller 111.

  The image on the original 108 fed on the original platen glass 107 is moved by the illumination lamp 101, the first mirror 102, the second mirror 103, and the fourth mirror 104 in the sub-scanning direction S, so that the image sensor 106. Is read by.

  When copying a document, an image read by the image sensor 106 is sent to an image forming apparatus (not shown), and an image is formed on a sheet based on the read image.

  When performing a remote scan, an image read by the image sensor 106 is sent to a computer (not shown) connected on a network and stored in a hard disk in the computer.

  When performing FAX transmission, an image read by the image sensor 106 is transmitted through a public line.

  FIG. 3 is an example of an image obtained by reading an image by placing an A4 size reference sheet (white paper) on the platen glass 107 of the image reading apparatus after it has been used considerably, and performing a predetermined image processing. A portion surrounded by a broken line in FIG. 3 is a portion where the conductive coat is peeled off by the document feeding operation and the luminance of the image data is high.

  As in this example, in the case of an image reading apparatus in which a document is fed by moving on a platen glass by a document feeding device or the like, a portion where friction is large occurs at a specific position on the platen glass. In many cases, the conductive coating becomes worn and becomes such a state. In particular, peeling due to abrasion of the conductive coating is conspicuous in the central portion in the main scanning direction and the portion corresponding to the position of the roller provided inside the document conveying belt 112.

  In the present embodiment, attention is paid to the position of the main scanning central portion 301, and the operation for detecting the degree of peeling of the conductive coating in that portion will be described with reference to FIGS. The control shown in the flowchart of FIG. 4 is executed by a control circuit 400 (not shown).

  The Dt reading position 302 is a sub-scanning position for reading an image during the main operation. When detecting the degree of peeling of the conductive coating, a reference sheet having a predetermined reflection density uniformly in the main scanning direction is placed on the platen glass 107 in advance.

  First, the illumination lamp 101, the first mirror 102, the second mirror 103, and the fourth mirror 104 are moved below the white plate 109, and an image on the white plate 109 is read (S401). An example of the read image is shown in FIG.

  Then, as shown in FIG. 5B, the read value 501 read in step S401 is corrected by the signal processing circuit shown in FIG. 7 to be a predetermined target value 502 for each pixel (S402). Details of the correction will be described below with reference to FIGS.

  FIG. 6 shows the configuration of the white plate 109, and the reading area 201 used for shading correction is arranged at a position where it can be read by the image sensor 106. As described above, the white plate 109 is covered with the cover glass 110, but the cover glass 110 is not provided with a conductive coating.

  FIG. 7 shows a signal processing circuit for the output signal of the image sensor 106. In FIG. 7, reference numerals 701 to 703 denote amplifier circuits that amplify the output signals of RGB so as to reach predetermined levels. Reference numerals 704 to 706 denote AD conversion circuits for converting each amplifier output into a digital signal. Reference numerals 707 to 709 denote black offset correction circuits that remove offset components from the output signals of the AD conversion circuits 704 to 706.

  Reference numerals 710 to 712 denote shading correction line memories, which store read signals of the white plate 109. Reference numerals 713 to 715 denote shading correction calculation circuits, which perform the shading correction calculation represented by the following equation with reference to the contents of the shading memories 710 to 712.

VOUTi = VINi × (SHTAR / Wi)
VOUTi: Shading correction output VINi: Shading correction input SHTAR: Shading correction target value Wi: White plate reading signal i: Pixel No.
By this shading correction calculation, the read value 501 read in step S401 described above is corrected so as to become a predetermined target value 502 for each pixel by the signal processing circuit of FIG.

  Next, the illumination lamp 101 is moved to the Dt reading position 302 below the reference sheet (S403), and the reference sheet placed on the platen glass 107 is read (S404).

  Here, an image obtained by reading the reference sheet is shown in FIG. Since the original platen glass 107 is provided with a conductive coating on the entire surface, the reading value 503 is smaller even when reading the one having the same reflection density as compared with the case where the conductive coating is not applied. This is because light is blocked and the amount of light is reduced as much as the conductive coating is applied. For example, when the conductive coat is completely peeled off, the read value 503 becomes equal to the target value 502.

  Next, the average value Dt504 (average value of the difference between the target value 502 and the read value 503) in the read area 505 in the main scanning direction of the read value 503 is calculated (S405). At this time, when the conductive coat is not peeled off, the average value Dt504 becomes large, and when the conductive coat is peeled off, the average value Dt504 becomes small.

  The average value Dt504 is compared with a reference value Dr506 that serves as a reference for determining the degree of wear, and the following processing is performed according to the comparison result (S406).

  When Dr ≦ Dt, it is determined that the conductive coating is lightly worn, and Dt is erased and the process ends.

  When Dr> Dt, it is determined that the conductive coating has been worn, and a message indicating that the wear on the platen glass 107 is being progressed is displayed on the display unit 800 provided on the operation unit (not shown). (S407). Then, the feeding operation from the document feeder is restricted (S408). For example, the display as shown in FIG.

  In step S407, a message indicating that the wear of the platen glass 107 is progressing is displayed, but a message for prompting replacement of the platen glass 107 as shown in FIG. 9 may be displayed. Thereby, the user can grasp the replacement time of the platen glass 107.

  In step S407, a screen for allowing the user to select whether or not to place an order for the platen glass 107 as shown in FIG. 10 may be displayed. According to the user's selection to place an order, an order for the platen glass 107 is made to a server at a service base connected to the image reading apparatus via a network. By placing an order, a service person at the service base can deliver the document table glass 107 to the user.

  Further, in step S408, the sheet feeding operation from the document feeding apparatus is restricted so that it cannot be performed. However, a screen for allowing the user to select whether or not to restrict the feeding operation as shown in FIG. 11 may be displayed. . This improves usability.

  Next, Example 2 will be described in detail below with reference to the drawings.

  In the first exemplary embodiment, a description will be given of a configuration in which a user reads a document set on a platen glass and a case of reading a document fed by a document feeding device on the same document glass. did.

  On the other hand, in the second embodiment, a document placement unit glass for reading a document set by a user and a document transport unit glass for reading a document fed by a document feeder are provided separately. The configuration of the case. With the image reading apparatus having such a configuration, the same effects as those of the first embodiment can be obtained.

  FIG. 12 is a diagram illustrating a configuration of an image reading apparatus on which the document feeder according to the second embodiment is mounted.

  When the user reads the first original 1201 set on the original placement unit glass 1202, the light source 1203 first irradiates the first original 1201 with light. The irradiated light passes through the slit 1204, is reflected by the first mirror 1205, the second mirror 1206, and the third mirror 1207, passes through the lens 1208, and forms an image on the image sensor 1209 such as a CCD.

  On the other hand, when reading the second document 1210 conveyed by the document conveying roller 1212, first, the light source 1203, the slit 1204, the first mirror 1205, the second mirror 1206, and the third mirror 1207 are placed on the document conveying unit glass 1211. Move down. Thereafter, the light source 1203 irradiates the second original 1210 with light, and the irradiated light forms an image on the image sensor 1209 as described above.

  The original transport unit glass 1211 is provided with a conductive coating, but is not applied to the original placement unit glass 1202. Since the glass is charged by the friction with the second original 1210 conveyed by the original conveying roller 1212, the original conveying unit glass 1211 needs a conductive coating for preventing charging. However, since the document placing portion glass 1202 hardly causes friction with the first document 1210, a conductive coating is not necessary.

  Therefore, the process for detecting the degree of peeling of the conductive coat is performed on the document transport unit glass 1211, but not on the document placement unit glass 1202 on which the conductive coat is not applied. The details of the operation for detecting the degree of peeling of the conductive coat are the same as those in the first embodiment, and therefore will be omitted.

  As described above, according to the present embodiment, since the degree of wear of the conductive coating on the platen glass can be detected in detail, the life or replacement time of the platen glass can be easily determined. By appropriately performing the document glass replacement timing, it is possible to reduce problems such as that a document due to electrostatic adsorption cannot be normally fed.

Configuration of image reader Configuration of an image reading device equipped with a belt-conveying document feeder The figure which shows the state where the conductive coat which was given to the platen glass was partly removed due to wear A flowchart for explaining the operation for detecting the degree of peeling of the conductive coating applied to the platen glass. The figure explaining the operation | movement which detects the peeling condition of the electroconductive coating applied to the platen glass. White plate for shading correction in image reader Block diagram of signal processing equipment Example of warning display when the platen glass is worn Example of warning display when the platen glass is worn Example of warning display when the platen glass is worn Example of warning display when the platen glass is worn Another configuration of image reading device equipped with document feeder

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Light source 102 1st mirror 103 2nd mirror 104 3rd mirror 105 Lens 106 Image sensor 107 Original plate glass 108 Original 109 White plate 110 Cover glass 111 Belt drive roller 112 Original conveyance belt 400 Control circuit 800 Display unit 1201 First original 1202 Document Placement Section Glass 1203 Light Source 1204 Slit 1205 First Mirror 1206 Second Mirror 1207 Third Mirror 1208 Lens 1209 Image Sensor 1210 Second Document 1211 Document Conveyance Section Glass 1212 Document Conveyance Roller

Claims (9)

An original conveying means for conveying an original;
A platen glass with a conductive coating that comes into contact with the document conveyed by the document conveying means;
Reading means for reading a white reference sheet through the platen glass;
Detecting means for detecting the degree of peeling of the conductive coating applied to the platen glass based on the image of the reference sheet read by the reading means;
An image reading apparatus comprising:   The image reading apparatus according to claim 1, further comprising a control unit that restricts conveyance of the document by the document conveyance unit in accordance with a detection result of the detection unit.   The image reading apparatus according to claim 1, further comprising a display unit that displays a message indicating that the wear of the platen glass is progressing according to a detection result of the detection unit.   2. The image reading apparatus according to claim 1, further comprising display means for displaying a message for requesting replacement of the platen glass in accordance with a detection result of the detection means.   The image reading apparatus according to claim 1, further comprising a display unit configured to display a selection screen for a user to select whether or not to order the platen glass according to a detection result of the detection unit. .   2. The display unit according to claim 1, further comprising a display unit that displays a selection screen for a user to select whether or not to limit the conveyance of the document by the document conveyance unit according to the detection result of the detection unit. Image reading device. Has a white plate for shading correction,
The image reading apparatus according to claim 1, wherein the reading unit performs shading correction by reading the white plate before reading the reference sheet. The reading means reads a predetermined area of the reference sheet;
The detecting means detects a degree of peeling of a conductive coat applied to the platen glass based on an image of a predetermined area of the reference sheet read by the reading means. The image reading apparatus according to claim 1. An original conveying means for conveying an original;
A document transport unit glass coated with a conductive coating and in contact with the document transported by the document transport means;
A document placement unit glass not provided with a conductive coating on which a document is placed by a user;
Reading means for reading a white reference sheet through the document conveying section glass;
Detecting means for detecting the degree of peeling of the conductive coating applied to the document conveying section glass based on the image of the reference sheet read by the reading means;
An image reading apparatus comprising:

Images