JP2020010175A - Document reading device - Google Patents

Abstract

To solve the problem in which, when a back surface reading unit reads a first white reference plate, it also reads interference fringes, due to an interference fringe generated when a document reading glass and a platen glass are brought into contact each other, so that shading correction processing of the backside reading unit cannot be performed correctly.SOLUTION: Before performing shading correction processing of a back side reading unit, interference fringes are detected using a surface reading unit capable of performing shading correction processing without being affected by interference fringes and a white plate placed on a document reading glass to prevent erroneous shading correction processing of the back side reading unit.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a technology of a document reading device that reads image information recorded on a document.

  As an image reading device applied to image forming devices such as copiers and facsimile machines, the purpose is to speed up the reading of documents, or the possibility of damage or breakage of documents during transport without complicating the transport system For the purpose of reducing the number of images, an apparatus capable of reading images on both sides of a document at once has been developed (see Patent Document 1).

  The image reading device described in Patent Document 1 has a configuration in which the front surface reading unit and the back surface reading unit are arranged close to and opposed to each other in order to make the device compact. There is described a technology in which a white reference plate for correcting the optical system of the back surface reading unit is provided at a position where the front surface reading unit does not hinder the optical path when optically reading the original, and the white reference plate is not easily stained. .

JP-A-2002-335380

  In the case of the apparatus configuration of Patent Literature 1, the back surface reading unit reads the white reference plate through the original reading glass and the original platen glass arranged opposite to the original reading glass. Further, the document reading glass and the document table glass are slightly separated from each other so that the document can pass smoothly during document transport.

  However, depending on changes in the installation environment (temperature and humidity) of the apparatus, the original reading glass or the original platen glass may be warped, and the original reading glass and the original platen glass may come into contact with each other. At this time, when the light source of the reading unit is turned on, interference of light may occur and a stripe pattern (hereinafter, referred to as an interference stripe) may occur. Due to the interference fringes, the white reference plate of the back surface reading unit cannot be normally read, and there is a problem that an abnormal image is generated when reading the document.

  SUMMARY OF THE INVENTION In order to solve the above-described problems, the present invention provides an original reading apparatus that includes an interference fringe determination processing unit that determines whether or not an interference fringe is generated and that issues an error notification when an interference fringe is detected. The purpose is to:

In order to achieve the above object, a document reading device according to the present invention is provided with:
Document loading means for loading a document (101), a document transport unit (105) for transporting the document, a front document reading unit (106b) for reading the document on the front surface to be transported, and a back document reading for reading the document on the back surface Unit (106a), a document reading glass (119) disposed between the back document reading unit (106a) and the document reading position (107a), and a document table disposed opposite to the document reading glass (119). Glass (126), a first white reference plate (125) for generating shading data of the back side document reading unit (106a), and a second white reference plate (125) for generating shading data of the front side document reading unit (106b). The white reference plate (127) and the back document reading unit (106a) read the first white reference plate (125) or the front document. (106b) shading data generating means (401, 405) for reading the second white reference plate (127) and generating shading data; and shading data holding means for storing shading data generated by the shading data generating means. (402), the white plate (128) disposed on the original reading glass (119), and the interference fringes generated by the contact between the original platen glass (126) and the original reading glass (119). A document reading apparatus having an interference fringe occurrence determining means (406) for determining whether or not there is an error, and a controller panel (470) for notifying an error to a user.
Before the shading data is generated by the shading data generating means (401, 405), the front original reading (106b) which has been subjected to shading correction by the correction coefficient generating means (401) for correcting the shading data is converted to the white plate (128). Is read, and whether or not interference fringes have occurred is determined by the interference fringe occurrence determining means (406).
If interference fringes have occurred, the reading of the back side document (106a) stops reading of the first white reference plate (125) and notifies an error in the controller panel (470).

Further, the document reading device according to the present invention,
The shading data generating means (401, 405) is in a non-contact state with the original platen glass (126) and the original reading glass (119) used when the interference fringe occurrence determining means (406) determines the occurrence of interference fringes. ), The document reading apparatus having the backup memory (402) holding the shading data of the back side reading unit 106a generated by
When it is determined by the interference fringe occurrence determining means (406) that an interference fringe has occurred, the back side original reading (106a) does not read the first white reference plate (125) and the back side original reading (106a). The shading data of (1) uses data stored in the backup memory (402).

  According to the document reading apparatus of the present invention, the shading-corrected front document reading unit reads the white plate, and the interference fringe generation determining unit detects the interference fringe generated by the contact between the platen glass and the document reading glass. It is possible to prevent the shading correction of the back side document reading unit from acquiring an incorrect shading correction coefficient due to the influence of interference fringes, and notify the user that the platen glass and the document reading glass are in contact. it can.

FIG. 2 is a configuration diagram of a document conveyance reading device. FIG. 3 is a control configuration diagram of the document conveyance reading device. This is an example of the occurrence of interference fringes. FIG. 6 is a diagram in which a second reading unit reads a white plate. FIG. 4 is a profile diagram of a white plate when interference fringes occur. FIG. 9 is a diagram illustrating an example of interference fringe detection when Red is used as an example. 5 is a flowchart of an interference fringe detection process described in the first embodiment. 9 is a flowchart illustrating a determination process (Red) described in the first embodiment. 9 is a flowchart of an interference fringe detection process described in a second embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 shows the configuration of a document transport reading device 120 equipped with an automatic document transport mechanism.

  In FIG. 1, reference numeral 101 denotes a document tray on which documents 102 are stacked. The original pick roller 121, the original separating roller 122, the original conveying roller 123, and the original offset roller 124 are driven by the original conveying motor 105 shown in the block diagram of FIG. A document 102 placed on a document tray 101 is fed.

  The back side document reading unit 106a reads the back side of the document 102 conveyed between the document reading glass 119 and the platen glass 126, and the front side document reading unit 106b reads the document between the document reading glass 119 and the platen glass 126. The surface of the original 102 conveyed is read. When the image reading of the document 102 by the document reading units 106a and 106b is completed, the document 102 is discharged to the discharge tray 108.

  There is a first white reference plate 125 for generating shading data of the document reading unit 106a disposed opposite to the back side document reading position 107a with the platen glass 126 interposed therebetween. Further, the platen glass 126 has a second white reference plate 125 for generating shading data of the front-side original reading unit 106b. The front-side original reading unit 106b is driven by a reader motor 152, and the front-side original reading unit 106b is The two white reference plate 125 can be read. The front original reading unit 106b is configured to be driven by a reader motor 152 to read a white plate 128 installed on the original reading glass and used for detecting an interference fringe described later.

  Each of the document reading units 106a and 106b has light guides 202a and 202b for irradiating the document 102 with light from the LED light sources 201a and 201b, CIS line sensors 203a and 203b, and lenses 204a and 204b.

  The CIS line sensor 203a photoelectrically converts reflected light from the document 102 guided by the lens 204a with a light receiving element, and outputs an electric signal corresponding to the amount of incident light. While the original 102 is being conveyed by the original reading device in the above configuration, the back surface of the original 102 is read at the original reading position 107b.

  The CIS line sensor 203b photoelectrically converts reflected light from the document 102 guided by the lens 204b with a light receiving element, and outputs an electric signal corresponding to the amount of incident light.

  With the above configuration, the surface of the original 102 is read at the original reading position 107a while the original 102 is conveyed by the original reading device.

  FIG. 2 is a diagram illustrating a control configuration of the document reading apparatus according to the embodiment of the present invention.

  Reference numeral 401 denotes a main CPU for controlling the document reading device, which includes an LED light source 201a and a CIS line sensor 203a of the front document reading unit 106a, an LED light source 201b and a CIS line sensor 203b of the back document reading unit 106b, a document conveying motor 105, The reader motor 152, the backup memory 402, and the controller panel 407 are controlled to control reading of a document image.

  The flow of the image signal will be described. The RGB three-color electric signals corresponding to the density of the document read by the CIS line sensor 203a or 203b are converted from analog electric signals into RGB three-color digital image signals by the A / D conversion circuit 403a or 403b.

  Next, the shading correction circuit 404 corrects the influence of the non-uniformity of the light amount of the LED light source 201a or 201b and the influence of the sensitivity variation of each pixel of each of the RGB colors of the CIS line sensor 203a or 203b.

  The CPU 401 receives the digital image signal from the shading correction circuit 404 and performs data transmission and reception and shading correction with a temporary SRAM for calculation 405 and a backup memory 402 described later.

  The backup memory 402 is a non-volatile RAM that stores shading data used when the shading correction circuit 404 performs a correction process. The backup memory 402 reads and writes data from the CPU 401, and transmits and receives data to and from the shading correction circuit 404 via the CPU 401. Is available.

  The calculation temporary RAM 405 is a RAM used by the CPU 401 when temporarily storing data of the backup memory 402 and the shading correction circuit 404, and is configured to transmit and receive data under the control of the CPU 401. ing.

  FIG. 3 shows a state of the first white reference plate 125 when the LED light source (back) 201a of the back side document reading unit 106a irradiates when the document reading glass 119 and the document table glass 126 are in non-contact and contact. .

  FIG. 3A shows a case where the original reading glass 119 and the original table glass 126 are not in contact with each other. In the above state, the back side document reading unit 106a can normally read the white member of the first white reference plate 125.

  However, when the original reading glass 119 and the original table glass 126 are in contact with each other as shown in FIG. 3B, when the LED light source (back) 201a of the back original reading unit 106a is irradiated, the original reading glass 119 and the original table Interference fringes are generated on the contact surface of the glass 126 due to irregular reflection of light. At this time, since the back side document reading unit 106a simultaneously reads the white member and the interference fringe of the first white reference plate 125, erroneous shading data is obtained when performing the back side shading correction processing. As a result, a problem arises in that the back side document reading unit 106a cannot read the document properly when reading the two-sided document.

  To prevent the above problem from occurring, it is necessary to detect whether or not interference fringes have occurred before starting the document reading operation. In this patent proposal, as a method of detecting interference fringes, as shown in FIG. 4, a white original 128 is used as a front original reading unit by using a front original reading unit 106b which has been subjected to shading correction by a second white reference plate 127 which is not affected by interference fringes. The data is read at 106b, and the CPU 401 determines whether or not interference fringes have occurred.

  FIG. 5 shows an example of the luminance profile when the white plate 128 is acquired by the front original reading unit 106b that has been subjected to shading correction by the second white reference plate 127 when the original reading glass 119 and the original platen glass 126 are in contact with each other. From FIG. 5, it can be confirmed that among the three color luminance (Red, Green, Blue) profiles, there is a characteristic in which the Red profile fluctuates from the Green, Blue profile. This interference fringe has the characteristic that the profile of any one of the three luminances fluctuates. This patent utilizes this feature.

The processing flow of interference fringe detection will be described. First, the white plate 128 is read by the front document reading unit 106b, and the luminance profiles of Red, Green, and Blue are acquired. FIG. 6 shows an example of interference fringe detection in the case of Red. As shown in FIG. 6, an average value Ave_r of the luminance profile of Red is acquired by the CPU 401. When the pixel position of the front original reading unit 106b is n, the pixel value of Red at the pixel position n is Dred (n), and an arbitrary threshold is THr, the variable for recording the result of the determination process of the pixel position n is Red ( If n), the CPU 401 executes the following determination processing.
| Dred (n) -Ave_r | ≧ THr⇒Red (n) = 1
| Dred (n) -Ave_r | <THr ⇒ Red (n) = 0
n = Dred (n) indicating a pixel position of the CIS line sensor 203b = Red pixel value THr at the pixel position n THr = threshold (arbitrary)
A flag for recording the result of the determination process of Red (n) = Dred (n) Similarly to Green and Green, the CPU 401 performs the same process for Red and Blue.

| Dgreen (n) −Ave_g | ≧ THg ⇒ Green (n) = 1
| Dgreen (n) -Ave_g | <THg ⇒ Green (n) = 0
Dred (n) = Green pixel value at pixel position n THg = threshold (arbitrary)
A flag for recording the result of the determination processing of Green (n) = Dgreen (n) | Dblue (n) −Ave_b | ≧ THb⇒Blue (n) = 1
| Dblue (n) -Ave_b | <THb ⇒ Blue (n) = 0
Dblue (n) = pixel value of Blue at pixel position n THb = threshold (arbitrary)
A flag for recording the result of the determination process of Blue (n) = Blue (n) After performing the above determination process, using the flags Red (n), Green (n), and Blue (n) at the pixel position n The CPU 401 determines whether or not interference fringes have occurred. The interference fringes are as described above. From FIG. 5, there is a characteristic that one color profile among the three color luminance (Red, Green, Blue) profiles is more varied than the other color profiles.

  Therefore, in this patent proposal, when Red (n) = Green (n) = Blue (n), it is determined that there is no interference fringe, and the other conditions are determined to be interference fringe, and the processing is performed. When the CPU 401 determines that all the pixels have no interference fringe, the back-side original reading unit 106a can normally read the first white reference plate 125, and thus reads the back-side original reading unit 106a and the first white reference plate 125 as they are, and outputs the shading data. Is calculated and the document is read. Conversely, if the CPU 401 finds a pixel determined to have an interference fringe, the back side document reading unit 106 a cannot read the first white reference plate 125 normally, so the CPU 401 notifies the user of an error on the controller panel 407. Then, the reading operation is stopped. By performing the above processing, occurrence of an abnormal image on the back side of the document due to interference fringes can be prevented.

  FIG. 7 is a flowchart showing the processing contents of the patent proposal.

  First, the CPU 401 drives the reader motor 151 to move the front document reading unit 106b to the second white reference plate 127 (S100), and the CPU 401 drives the CIS line sensor 203b and the LED light source 201b of the front document reading unit 106b, The second white reference plate 127 is sampled (S101), and shading data for the front side document reading unit 106b is acquired and stored in the backup memory 402 (S102).

  Next, the CPU 401 drives the reader motor 151 to move the front-side original reading unit 106b to the white plate 128 (S103). The CPU 401 drives the CIS line sensor 203b and the LED light source 201b of the front-side original reading unit 106b. The read value is obtained, the shading correction circuit 404 obtains the pixel value of the white plate 128 using the shading data for the front document reading unit 106b stored in the backup memory 402, and stores it in the calculation temporary SRAM 405 (S104). .

  After obtaining the pixel values of the white plate 128, the CPU 401 calculates the average values Ave_r, Ave_g, Ave_b of each color using the pixel values Dred (n), Dgreen (n), and Dblue (n) of the three colors of the white plate 128 (S105). . After acquiring the average values Ave_r, Ave_g, and Ave_b, the CPU 401 uses the pixel values Dred (n), Dgreen (n), and Dblue (n) stored in the calculation temporary SRAM 405 to perform a determination process described below at the pixel position n. Is performed for each color of Red, Green, and Blue, and the results of the determination processing for each color are output as Red (n), Green (n), and Blue (n) (S106, S107, and S108).

  After outputting Red (n), Green (n), and Blue (n), a determination process is performed to determine whether Red (n) = Green (n) = Blue (n) (S109). When Red (n) = Green (n) = Blue (n) (S109_Yes), it is determined whether n is the last pixel position (S110). If n is not the last pixel position (S110_No), n = n + 1 (S112), and the process returns to the determination processing. If n is the last pixel position (S110_Yes), the CPU 401 determines that no interference fringe has occurred, calculates shading data for the back side document reading unit 106a, and stores it in the backup memory 402 (S111). A document is read (S113). When Red (n) = Green (n) = Blue (n) is not satisfied (S109_No), the CPU 401 causes the controller panel 407 to display an error code having an interference fringe (S114), and stops the reading operation (S115). .

  FIG. 8 is a flowchart showing the flow of the above-described determination process (Red) (S106).

  First, | Dred (n) −Ave_r using the pixel value Dred (n) at the pixel position n stored in the temporary SRAM for calculation 405, the average value Ave_r of all Red pixels calculated by the CPU 401, and the threshold THred arbitrarily set. It is determined whether | ≧ THred (S201). When | Dred (n) −Ave_r | ≧ THred (S201_Yes), Red (n) is set to 1 as a result of the determination processing. Conversely, when | Dred (n) −Ave_r | ≧ THred is not satisfied (S201_No). Red (n) is set to 1 as a result of the determination process.

  The same processing as the above determination processing (Red) is also performed in Green (S107) and Blue (S108), and the determination processing results Green (n) and Blue (n) at the pixel position n are output.

  In the first embodiment, the processing for stopping the reading operation when the interference fringe occurs is described. However, the processing for continuing the reading operation is described below as a second embodiment. When the CPU 401 determines that there is interference fringe, the CPU 401 reads out the shading backup data of the back side document reading unit 106a stored in the backup memory 402 in advance, and performs document reading. By performing the above processing, interference fringes can be detected, and the influence of the reading operation of the back side document reading unit 106a can be reduced.

  FIG. 9 is a flowchart showing the processing contents of the second embodiment.

  First, the CPU 401 drives the reader motor 151 to move the front document reading unit 106b to the second white reference plate 127 (S300), and the CPU 401 drives the CIS line sensor 203b and the LED light source 201b of the front document reading unit 106b, The second white reference plate 127 is sampled (S301), and shading data for the front original reading unit 106b is acquired and stored in the backup memory 402 (S302).

  Next, the CPU 401 drives the reader motor 151 to move the front-side original reading unit 106b to the white plate 128 (S303). The CPU 401 drives the CIS line sensor 203b and the LED light source 201b of the front-side original reading unit 106b. The read value is obtained, the shading correction circuit 404 obtains the pixel value of the white plate 128 using the shading data for the front side document reading unit 106b stored in the backup memory 402, and stores it in the calculation temporary SRAM 405 (S304). .

  After obtaining the pixel values of the white plate 128, the CPU 401 calculates the average values Ave_r, Ave_g, and Ave_b of each color using the pixel values Dred (n), Dgreen (n), and Dblue (n) of the three colors of the white plate 128 (S305). . After obtaining the average values Ave_r, Ave_g, and Ave_b, the CPU 401 uses the pixel values Dred (n), Dgreen (n), and Dblue (n) stored in the calculation temporary SRAM 405 to perform the determination processing at the pixel position n. , Green, and Blue for each color, and outputs Red (n), Green (n), and Blue (n) as a result of the determination process for each color (S306, S307, S308).

  After outputting Red (n), Green (n), and Blue (n), a determination process is performed to determine whether Red (n) = Green (n) = Blue (n) (S309). When Red (n) = Green (n) = Blue (n) (S309_Yes), it is determined whether n is the last pixel position (S310). If n is not the last pixel position (S310_No), n = n + 1 (S312), and the process returns to the determination processing. If n is the last pixel position (S310_Yes), the CPU 401 determines that no interference fringe has occurred, calculates shading data for the back side document reading unit 106a, and stores it in the backup memory 402 (S311). An original is read (S315). When Red (n) = Green (n) = Blue (n) is not satisfied (S309_No), the CPU 401 reads out the shading backup data of the back side document reading unit 106a stored in the backup memory 402 (S313), and performs document reading. (S314).

101 document tray, 102 documents, 105 document transport motor,
106a back side document reading unit, 106b front side document reading unit,
107a Back document reading position, 107b Front document reading position,
108 output tray, 119 original reading glass, 120 original transport reading device,
121 document pick roller, 122 document separation roller, 123 document transport roller,
124 document offset roller, 125 first white reference plate, 126 platen glass,
127 second white reference plate, 128 white plate, 150 document reading device,
151 document feed motor drive circuit,
152 leader motor, 153 leader motor drive circuit,
201a LED light source (back),
202a light guide (back), 203a CIS line sensor (back),
204a lens (rear), 201b LED light source (front), 202b light guide (front),
203b CIS line sensor (table), 204b lens (table), 401 CPU,
402 backup memory, 403a A / D conversion circuit (back),
403b A / D conversion circuit (table), 404 shading correction circuit,
405 Temporary SRAM for calculation, 407 Controller panel, 500 reference members

Claims (2)

Document loading means for loading a document (101), a document transport unit (105) for transporting the document, a front document reading unit (106b) for reading the document on the front surface to be transported, and a back document reading for reading the document on the back surface Unit (106a), a document reading glass (119) disposed between the back document reading unit (106a) and the document reading position (107a), and a document table disposed opposite to the document reading glass (119). Glass (126), a first white reference plate (125) for generating shading data of the back side document reading unit (106a), and a second white reference plate (125) for generating shading data of the front side document reading unit (106b). The white reference plate (127) and the back document reading unit (106a) read the first white reference plate (125) or the front document. (106b) shading data generating means (401, 405) for reading the second white reference plate (127) and generating shading data; and shading data holding means for storing shading data generated by the shading data generating means. (402), the white plate (128) disposed on the original reading glass (119), and the interference fringes generated by the contact between the original platen glass (126) and the original reading glass (119). A document reading apparatus having an interference fringe occurrence determining means (406) for determining whether or not there is an error, and a controller panel (470) for notifying an error to a user.
A correction coefficient generating unit that corrects the shading data before the back original reading unit (106a) reads the first white reference plate (125) and generates the shading data by the shading data generating unit (401, 405); The front side document reading (106b), which has been subjected to shading correction in (401), reads the white plate (128), and determines whether or not interference fringes are generated by the interference fringe generation determining means (406).
An image reading apparatus, wherein reading is stopped when an interference fringe has occurred, and an error in the controller panel (470) is notified. Document loading means for loading a document (101), a document transport unit (105) for transporting the document, a front document reading unit (106b) for reading the document on the front surface to be transported, and a back document reading for reading the document on the back surface Unit (106a), a document reading glass (119) disposed between the back document reading unit (106a) and the document reading position (107a), and a document table disposed opposite to the document reading glass (119). Glass (126), a first white reference plate (125) for generating shading data of the back side document reading unit (106a), and a second white reference plate (125) for generating shading data of the front side document reading unit (106b). The white reference plate (127) and the back document reading unit (106a) read the first white reference plate (125) or the front document. (106b) shading data generating means (401, 405) for reading the second white reference plate (127) and generating shading data; and shading data holding means for storing shading data generated by the shading data generating means. (402), the white plate (128) disposed on the original reading glass (119), and the interference fringes generated by the contact between the original platen glass (126) and the original reading glass (119). An interference fringe occurrence determining unit (406) for determining whether or not the original platen glass (126) and the original reading glass ( 119) in a non-contact state by the shading data generating means (401, 405). In the original reading apparatus having a backup memory which holds (402) shading data of the generated back face read unit 106a Te,
When it is determined by the interference fringe occurrence determining means (406) that an interference fringe has occurred, the back side original reading (106a) does not read the first white reference plate (125) and the back side original reading (106a). The document reading device according to (1), wherein data stored in the backup memory (402) is used as shading data.