JP2006245995A - Image-reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect abnormality in shading data under an appropriate condition by detecting stain sticking to a contact glass or reference member during a shading correction process. <P>SOLUTION: The image reading apparatus reads a white reference member (S11), generates white shading data (S12) and inputs it to a min-value detecting circuit. The min-value detecting circuit detects min-value of white shading data (S13). Whether the white shading data are abnormal or not is decided by comparing the min-value to a comparison value (S14). If the white shading data are abnormal (S14; Y), it is decided whether the section in which the abnormality of data exists is outside the range of reading an original (S15). If it is not outside the reading of original (S15; N), it is decided as being abnormal, and an abnormal signal is outputted. Reading operation of an original image is interrupted (S16), and an alarm is displayed for a user (S17). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus having a shading correction function for correcting sensitivity variations and illumination unevenness.

2. Description of the Related Art In recent years, a technique has been developed for optically reading an image such as a picture or a photograph with a contact line image sensor, a CCD (charge coupled device) image sensor, or the like, and converting the read electric signal into digital information. Along with this, facsimile machines, electronic copying machines, compound machines, and the like using scanner devices equipped with high-performance sensors have become widespread.
When a document image is read by a light receiving element using the image sensor as described above, shading correction that corrects variations in the main scanning direction of the illuminance of the exposure lamp, which is a light source, and changes in the amount of light due to the passage of lighting time is performed. Done.

This shading correction is executed by correcting the electrical signal of the document image output from the light receiving element based on the white correction data and the black correction data.
The white correction data and black correction data used here are generated in the scanner device before or during reading of the original image.
Each time the original is read, these correction data are read based on the reference plate serving as a reference for the color (white and black) density arranged at a predetermined position of the scanner device and based on the read data of the reference plate. Be able to.

By the way, in an image reading apparatus using a contact image sensor, a document is read while being conveyed while being in contact with a contact glass. For this reason, dust, toner, and paper dust attached to the document are likely to adhere to the surface of the white reference plate and contact glass for generating shading data. If these dust adheres to the optical path of the white reference plate or contact glass, it is normal. There was a problem that it was not possible to generate proper shading data.
Therefore, techniques for solving the problems in the shading process including the following patent documents have been proposed.
JP 2002-152510 A JP 2000-216963 A

Patent Document 1 proposes a technique for generating white shading data that is not easily affected by dust or the like.
Specifically, the white shading data is kept uniform by selecting data of a certain area of the surface of the white reference member that is not soiled to obtain white shading data, and high-quality image reading is performed. Can do.
Patent Document 2 proposes a technique for detecting a shading abnormality when setting a document in order to suppress performing unnecessary image forming processing.

However, in the image reading apparatus described in Patent Document 1, although the influence of the dirt attached to the white reference member can be avoided, the influence of the dirt attached to the contact glass cannot be suppressed.
Accordingly, an object of the present invention is to provide an image reading apparatus that can detect dirt adhering to contact glass, a reference member, etc. properly during shading correction processing, and detect abnormal shading data under appropriate conditions. Is to provide.

  According to the first aspect of the present invention, a light source that irradiates a document, an image data generation unit that converts optical document information irradiated by the light source into an electrical signal and generates read image data, and white shading correction of the read image A reference white reference member, a shading data generation means for optically reading the white reference member and generating shading data, and the shading data for the image data generated by the read image data generation means. A correction means for performing white shading correction, a detection means for detecting the size of the original, a comparison means for comparing the shading data generated by the shading data generation means with a predetermined reference value, and the comparison The shading having a value smaller than the predetermined reference value as a result of comparison by means When the data is detected, it is determined whether or not an area where the shading data having a value smaller than the predetermined reference value is overlapped with the size area of the document image detected by the detecting means. And an area in which the shading data having a value smaller than the predetermined reference value exists by the determination means is a size area of the original image detected by the detection means or a document size readable by the image reading apparatus. An output means for outputting an abnormal signal when it is determined that the area overlaps with the area is achieved.

According to a second aspect of the invention, in the first aspect of the invention, the predetermined reference value can be set to an arbitrary value.
According to a third aspect of the present invention, in the first or second aspect of the present invention, when the abnormal signal is output by the output means, a warning is displayed to urge cleaning of the white reference member and the image reading unit. Display means.
According to a fourth aspect of the present invention, in the first, second, or third aspect of the invention, when the image forming apparatus equipped with the image reading apparatus is turned on or after the final original reading process, A series of shading data abnormality detection processing is performed by the comparison unit, the determination unit, and the output unit.

According to the first aspect of the present invention, it is possible to appropriately detect only the abnormality of the shading data that affects the document image reading process.
According to the second aspect of the invention, since the reference value can be set to an arbitrary value, the allowable level of abnormal data in the shading data can be set arbitrarily. That is, the abnormality detection level can be varied.
According to the third aspect of the present invention, it is possible to appropriately prompt the user to perform the processing by providing the display means for displaying a warning for prompting the cleaning of the white reference member and the image reading unit. This facilitates maintaining stable shading data.
According to the fourth aspect of the present invention, when the power to the image forming apparatus is turned on or after the reading process of the final document, the time until the reading of the first document image is performed by performing the abnormality detection process of the shading data. (First reading time) can be shortened, and usability can be further improved.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS.
FIG. 1 is a cross-sectional view showing a schematic configuration of the electronic copying apparatus according to the present embodiment.
The electronic copying apparatus includes an image reading device 1 including an image scanner device, and an image forming unit 30 that forms an image on a sheet by electrophotography based on image data read by the image reading device 1.
The image reading apparatus 1 includes a first reading unit 11 including a first contact glass 3, a second contact glass 4, a lamp 5, a first mirror 6, a second mirror 7, a third mirror 8, a lens 9, a CCD 10, and the like. have.
The lamp 5 and the first mirror 6 are mounted on a first carriage (not shown), and the second mirror 7 and the third mirror 8 are mounted on a second carriage (not shown).

The image reading apparatus 1 moves the first carriage and the second carriage by a motor (not shown) to move in the sub-scanning direction that is the left-right direction in FIG. Then, the original fixedly set on the first contact glass 3 is main-scanned and sub-scanned to read the image of the original.
The image reading apparatus 1 includes an ADF (Auto Document Feeder) 20.
The ADF 20 is attached to the upper part of the main body housing 2 so that the upper surface of the first contact glass 3 can be opened and closed. By opening the ADF 20, a document can be set on the first contact glass 3.
The ADF 20 is configured to function as a pressure plate that presses the original against the first contact glass 3 when the original is set on the first contact glass 3 and is closed.

The ADF 20 includes a document table 21, a paper feed unit 22, a document conveyance path 23, a plurality of conveyance rollers 24 disposed along the document conveyance path 23, and a first reading disposed in contact with the second contact glass 4. The roller 25, the second reading roller 26, the contact image sensor 27, and the document discharge unit 28 are configured.
The ADF 20 separates a plurality of documents set on the document table 21 by the sheet feeding unit 22 one by one and sends them out to the document conveyance path 23. Further, the document sent to the document transport path 23 is transported between the first reading roller 25 and the second contact glass 4 by the transport roller 24.
When reading an image of a document conveyed by the ADF 20, the image reading apparatus 1 moves the first carriage and the second carriage to a position on the second contact glass 4 side.
Then, light from the lamp 5 is irradiated on one surface (for example, the front surface) of the document conveyed between the second contact glass 4 and the first reading roller 25.

The reflected light reflected from the surface of the document is sequentially reflected by the first mirror 6, the second mirror 7 and the third mirror 8 and is incident on the lens 9.
Light is condensed on the CCD 10 by the lens 9 and photoelectrically converted by the CCD 10 to read an image on the surface of the conveyed document.
The first reading roller 25 is rotationally driven by a stepping motor (not shown) at the same speed as the conveying roller 24 and conveys the document while pressing it against the second contact glass 4.
The ADF 20 conveys the original whose surface image is read between the second reading roller 26 and the contact image sensor 27 by the conveying roller 24. Further, the paper is discharged onto the document discharge unit 28 by the transport roller 24.
The second reading roller 26 is rotationally driven by a stepping motor (not shown) at the same speed as the conveying roller 24, and maintains a constant distance between the back surface of the document and the contact image sensor 27.

If the document has images formed on both sides, the contact image sensor 27 reads an image on the other side (back side) of the document conveyed between the second reading roller 26 and the contact image sensor 27. .
The image forming unit 30 includes a photoreceptor 31, a writing unit 32, a developing unit 33, a transfer unit 34, a transport unit 35, a fixing unit 36, a transport switching paper discharge unit 37, a reversing unit 38, a duplex transport unit 39, and a paper feed tray. It consists of a group 40, a side transport unit 41, and the like.
The image forming unit 30 uniformly charges the surface of the photoconductor 31 with a charger (not shown), and writes on the surface of the photoconductor 31 based on the image read by the first reading unit 11 or the contact image sensor 27. The image is written by the embedding unit 32 to form an electrostatic latent image.
The image forming unit 30 supplies toner from the developing unit 33 to the photoreceptor 31 on which the electrostatic latent image is formed, and visualizes it as a toner image.

The image forming unit 30 causes the transfer unit 34 to transfer the toner image visualized on the photoreceptor 31 onto the paper P. The paper P is configured to be fed from one of the paper feed tray groups 40 and transported by the side transport unit 41.
Then, the image forming unit 30 conveys the paper P on which the toner image is transferred to the fixing unit 36 by the conveying unit 35 and performs the fixing process by the fixing unit 36. The paper P passes through the conveyance switching paper discharge unit 37 and is then discharged onto a paper discharge tray 42 provided on the side surface of the main body housing 2.
The conveyance switching paper discharge unit 37 conveys the reversing unit 38 for reversing the front and back surfaces of the paper P and the paper P reversed by the reversing unit 38 between the photosensitive member 31 and the transfer unit 34 via the side conveying unit 41. A duplex transport unit 39 is connected.
When reverse paper discharge or double-sided recording is selected, the conveyance switching paper discharge unit 37 sends the paper P on which the image is formed on one side and has been fixed to the reverse unit 38.

When the reverse discharge is selected, the reversing unit 38 temporarily pulls the paper P sent from the conveyance switching paper discharge unit 37 and reverses the front and back surfaces of the paper P. In this state, the paper P is sent to the conveyance switching paper discharge unit 37. The conveyance switching paper discharge unit 37 discharges the paper P whose front and back surfaces are reversed by the reversing unit 38 onto the paper discharge tray 42.
When duplex recording is selected, the duplex conveyance unit 39 draws the paper P drawn by the reversing unit 38 and sends it to the side conveyance unit 41.
The side conveyance unit 41 again conveys the paper P between the photoconductor 31 and the transfer unit 34, and forms an image on the back surface.

FIG. 2 is an enlarged view of the contact image sensor 27 and its peripheral portion.
As shown in FIG. 2, the second reading roller 26 is disposed to face the CCD of the contact image sensor 27.
The second reading roller 26 has a cross-sectional shape that is substantially circular. The second reading roller 26 is formed of a white member made of rubber or resin.
A reference white reading surface 26 a extending along the axial direction of the second reading roller 26 is formed on a part of the outer peripheral portion of the second reading roller 26.
The reference white reading surface 26 a has a center of curvature on a straight line orthogonal to the axis of the second reading roller 26 and is formed by a convex curved surface located inside the maximum outer peripheral surface locus of the second reading roller 26. Yes.

FIG. 3 is a block diagram showing electrical connection of a control system in the image reading apparatus 1 according to the present embodiment.
The image reading apparatus 1 includes a contact image sensor 27, a controller 51, a main body control unit 52, an operation unit 53, an image processing circuit 54, and the like.
The main body control unit (control unit) 52 includes a CPU (Central Processing Unit) and controls the entire image reading apparatus 1.
The controller 51 is connected to a motor that drives the conveyance roller 24 shown in FIG. 1, various actuators of the ADF 20, sensors, and the like, and controls them.
The operation unit 53 is provided with various keys for performing various operations of the electronic copying apparatus according to the present embodiment, an LCD (liquid crystal display), and the like. The LCD functions as warning means for displaying and outputting various information, for example, a shading data abnormality alarm and a message (alarm) prompting the user to clean when the shading data is abnormal.

The contact image sensor 27 includes a light source 61, a sensor chip 62 including a CCD, an AMP circuit 63, an A / D conversion circuit 64, an image processing circuit 65, a frame memory 66, an output control circuit 67, an I / F circuit 68, and the like. I have.
Light is emitted from the light source 61 to the document by a lighting control signal from the controller 51, and the light reflected from the document is condensed on the sensor chip 62 by a lens (not shown).
The contact image sensor 27 reads an image of the document at a timing when the document reaches the contact image sensor 27 by a gate signal from the controller 51, and reads the read image data as an AMP circuit 63, an A / D conversion circuit 64, and an image. The data is temporarily stored in the frame memory 66 via the processing circuit 65.

The contact image sensor 27 transfers the image data stored in the frame memory 66 to the main body control unit 52 via the output control circuit 67 and the I / F circuit 68, and the main body control unit 52 reads the image data obtained by reading the back side of the document. Is transferred to the image processing circuit 54.
In the contact image sensor 27, the above-described parts are housed in a predetermined case, and a contact glass is provided on the surface on the second reading roller 26 side. The image reading apparatus 1 reads the original conveyed between the second reading roller 26 and the reference white reading surface 26 a of the second reading roller 26 through the contact glass.
When the double-sided copy mode is selected, the image reading apparatus 1 conveys the originals set on the original table 21 one by one to the original conveyance path 23 with the front side facing upward, and the first reading unit 11 performs the front side The image on the back side is read by the contact image sensor 27.

The electronic copying apparatus records and outputs the images read by the first reading unit 11 and the contact image sensor 27 on the front and back surfaces of the same sheet P, and performs double-sided copying.
The image reading device 1 and the image processing circuit 54 perform image processing such as black shading correction, white shading correction, and γ correction on the image data of the document.
Note that white shading data used for white shading correction is created by reading the reference white reading surface 26 a of the second reading roller 26 that is disposed opposite to the sensor chip 62 in the contact image sensor 27.

FIG. 4 is a block diagram showing the configuration of the white shading correction circuit 70.
The image processing circuit 54 is provided with a white shading correction circuit 70 as shown in FIG.
The white shading correction circuit 70 includes a shading data generation circuit 71, an abnormality detection circuit 72, and a shading calculation circuit 73. In the following description, a case where image data from the contact image sensor 27 is input to the white shading correction circuit 70 will be described.
The shading data generation circuit 71 includes an average value circuit 74, a first comparison circuit 75, and a FIFO (First-In First-Out) 76.
The abnormality detection circuit 72 includes a min value detection circuit 77 and a second comparison circuit 78.
In the shading data generation circuit 71, image data when the reference white reading surface 26 a of the second reading roller 26 is read from the contact image sensor 27 is input to the average value circuit 74.

Then, the average value circuit 74 divides the image data from the contact image sensor 27 when the reference white reading surface 26a of the second reading roller 26 is read into m blocks for each L line, and L lines in each block. Is obtained and output to the first comparison circuit 75. That is, the average value circuit 74 obtains the average value of the image data of each pixel in each line in each block.
In this case, it is desirable that the width of each block (number of lines L) is smaller than the width of the reference white reading surface 26a (that is, the number of lines L is smaller than the number of reading lines of the reference white reading surface 26a).
Further, the reading range of the second reading roller 26 is not limited to one rotation, but the range exceeding the one rotation of the second reading roller 26, for example, two rotations and three rotations, is read by the second reading roller 26. As a range, one block of the surface of the second reading roller 26 may be divided into blocks, and the width of each block may be set so that a fraction is obtained.

Next, the shading data generation circuit 71 obtains the peak value of each average value of each block obtained by the average value circuit 74 using the first comparison circuit 75 and the FIFO 76.
When the average value of each block is sequentially output from the average value circuit 74 to the first comparison circuit 75, the first comparison circuit 75 compares the average value of the preceding block with the average value of the succeeding block to obtain a value. The larger one is output to the FIFO 76.
The FIFO 76 stores the maximum value among the average values of the preceding blocks, and sequentially outputs it to the first comparison circuit 75.
The shading data generation circuit 71 repeats the above process for all blocks and stores the peak value in the FIFO 76. The shading data generation circuit 71 outputs this peak value to the min value detection circuit 77 of the abnormality detection circuit 72 as white shading data.

The min value detection circuit 77 of the abnormality detection circuit 72 detects the min value (minimum value) of the white shading data input from the shading data generation circuit 71 and outputs the detected min value to the second comparison circuit 78.
Further, the min value detection circuit 77 outputs the data after the min value detection processing to the shading calculation circuit 73.
The second comparison circuit 78 is configured to receive a preset comparison value (comparison reference value). The second comparison circuit 78 compares the min value of the white shading data input from the min value detection circuit 77 with the comparison value.
Then, when the min value of the white shading data is smaller than the comparison value and a predetermined condition described later is satisfied, the second comparison circuit 78 determines that an abnormality has occurred and outputs an abnormality signal to the main body control unit 52.

When an abnormality signal is input from the abnormality detection circuit 72, the main body control unit 52 causes the LCD of the operation unit 53 to display and output a message (alarm) prompting the user to stop (stop) the reading operation and clean the user.
Note that the alarm that prompts the user to clean the optical path is not limited to that displayed on the LCD of the operation unit 53. For example, the alarm message may be output by voice, Both audio outputs may be performed.
Further, the shading calculation circuit 73 receives the white shading data (min value detection processing completed) from the shading data generation circuit 71 and the image data obtained by reading the original of the contact image sensor 27.
The shading calculation circuit 73 performs shading correction of the image data of the document using the white shading data.
The electronic copying apparatus according to the present embodiment is provided with a detection device (not shown) that detects the size of a document read by the image reading device 1. The document size data detected by the detection device is attached to the white shading data.

Next, the operation of the abnormality detection process during the shading correction process of the electronic copying apparatus configured as described above will be described.
In the electronic copying apparatus according to the present embodiment, the abnormality of white shading data when the contact image sensor 27 reads the second reading roller 26 is appropriately determined based on the min value of the shading data and the document size data, In addition to preventing unnecessary reading and copying operations, an image with good reading quality is read.

FIG. 5 is a flowchart showing the procedure of the abnormality detection processing operation during the shading correction processing of the image reading apparatus according to the present embodiment.
First, the image reading apparatus 1 in the electronic copying apparatus performs a reading process of the reference white reading surface 26a of the second reading roller 26 as a white reference member at the time of shading correction or at an arbitrary timing (step 11).
Note that the reading process of the reference white reading surface 26 a is performed over a readable document size area in the image reading apparatus 1.
Next, the shading data generation circuit 71 shown in FIG. 4 generates white shading data as described above (step 12).
The image reading apparatus 1 inputs the white shading data generated by the shading data generation circuit 71 to the min value detection circuit 77 of the abnormality detection circuit 72.

Then, the min value detection circuit 77 detects the min value of the white shading data (step 13).
The image reading apparatus 1 determines whether the white shading data is abnormal (step 14).
Specifically, the min value of the white shading data is compared with a preset comparison value in the second comparison circuit 78 to determine whether or not the min value of the white shading data is smaller than the comparison value.
The second comparison circuit 78 determines that the white value of the shading data is normal if the value is larger than the comparison value, and determines that the value is abnormal if the min value of the shading data is smaller than the comparison value. The result is output to the main body control unit 52.
If the white shading data is not abnormal (step 14; N), the abnormality detection process is terminated as it is.

On the other hand, when the white shading data is abnormal (step 14; Y), the image reading apparatus 1 reads a region where the white shading data is abnormal, that is, a region including a value smaller than the comparison value in the white shading data. It is determined whether or not the document is out of range (step 15).
When the part where the white shading data abnormality exists is outside the range of the read original (step 15; Y), the abnormality detection process is finished as it is.
On the other hand, when the part where the abnormality of the white shading data exists is not outside the range of the read document (step 15; N), the abnormality detection circuit 72 determines that there is an abnormality and outputs an abnormality signal to the main body control unit 52.
That is, as shown in FIG. 6, when a region (part) lower than the comparison level (comparison value) of the white shading data is detected, when the size of the read document is A4 size, the white shading data is abnormal. It is determined that the existing part is outside the range of the read document.

Also, as shown in FIG. 6, when the size of the read document is A3 size, it is determined that the portion where the white shading data abnormality exists is within the range of the read document.
That is, when a portion where white shading data abnormality exists is applied to the read document, the abnormality detection circuit 72 determines that there is an abnormality (with an error) and outputs an abnormality signal to the main body control unit 52.
Even when there is an abnormality in white shading data, if the portion where the abnormality in white shading data is not applied to the scanned document, the image reading process will not be affected, so that image formation is performed normally. Processing can continue.
Therefore, when a portion where white shading data abnormality exists is not applied to the read document, it is determined that there is no abnormality (no error), and no abnormality signal is output.
When an abnormal signal is output to the main body control unit 52, the main body control unit 52 transmits a signal for stopping the reading process of the document image to a predetermined part of the image reading apparatus 1 and stops the reading operation of the document image (see FIG. Step 16).

Further, the main body control unit 52 displays a message (alarm) to urge the user to clean on the operation unit 53 (step 17), and ends the abnormality detection process.
When the abnormality detection process is completed without going through the process of step 17, normal processing is continued under the control of the main body control unit 52.
The normal processing is, for example, performing a normal document reading operation, and shading the image data of the document read by the contact image sensor 27 by the shading calculation circuit 73 based on the shading data generated by the shading data generation circuit 71. The process which performs a correction process and continues an image formation process is shown.
Further, when an abnormal signal is output to the main body control unit 52, it may be controlled so as to regulate the reading width of the document instead of stopping the image reading process. Specifically, the reading range of the document is set to an area that does not overlap with a portion where white shading data abnormality exists.

As described above, according to the present embodiment, it is possible to prevent a useless reading operation by detecting a shading abnormality based on the value of the white shading data and the size data of the read original, and the usability. It is possible to obtain a high-quality read image while improving the image quality. That is, the processing can be continued without interrupting the user's work as much as possible.
Further, by displaying a message (alarm) prompting the user to clean, stable shading data acquisition can be appropriately ensured, and a high-quality read image free from streaks and unevenness can be obtained. .

Further, as shown in FIG. 7, the detection of the presence or absence of white shading abnormality in the image reading apparatus 1 according to the present embodiment may be performed at the end of the copy process, that is, the image forming process.
Specifically, the image reading apparatus 1 determines whether or not the copying process in the electronic copying apparatus, that is, the image forming process has been completed (step 21).
If the copy process has not been completed (step 21; N), the image reading apparatus 1 stands by until the copy process is completed.
On the other hand, when the copy process is completed (step 21; Y), the image reading apparatus 1 in the electronic copying apparatus performs a reading process of the reference white reading surface 26a of the second reading roller 26 as a white reference member (step 22). .
Note that the reading process of the reference white reading surface 26 a is performed over a readable document size area in the image reading apparatus 1.

Next, the shading data generation circuit 71 shown in FIG. 4 generates white shading data as described above (step 23).
The image reading apparatus 1 inputs the white shading data generated by the shading data generation circuit 71 to the min value detection circuit 77 of the abnormality detection circuit 72.
Then, the min value detection circuit 77 detects the min value of the white shading data (step 24).
The image reading apparatus 1 determines whether or not the white shading data is abnormal (step 25).
Specifically, the min value of the white shading data is compared with a preset comparison value in the second comparison circuit 78 to determine whether or not the min value of the white shading data is smaller than the comparison value.

The second comparison circuit 78 determines that the white value of the shading data is normal if the value is larger than the comparison value, and determines that the value is abnormal if the min value of the shading data is smaller than the comparison value. The result is output to the main body control unit 52.
If the white shading data is not abnormal (step 25; N), the abnormality detection process is terminated as it is.
On the other hand, when the white shading data is abnormal (step 25; Y), the image reading apparatus 1 reads a region where the white shading data is abnormal, that is, a region including a value smaller than the comparison value in the white shading data. It is determined whether or not the document is out of range (step 26).
If the part where the white shading data abnormality exists is outside the range of the read document (step 26; Y), the abnormality detection process is ended as it is.

On the other hand, when the part where the abnormality of the white shading data exists is not outside the range of the read document (step 26; N), the abnormality detection circuit 72 determines that it is abnormal and outputs an abnormality signal to the main body control unit 52.
When an abnormal signal is output to the main body control unit 52, the main body control unit 52 displays a message (alarm) prompting the user to clean it on the operation unit 53 (step 27), and ends the abnormality detection process.
In this way, by performing the shading data abnormality determination process at the end of the copy process, that is, the image forming process, the time until the first original image is read (first reading time) can be shortened. The property can be further improved.

In addition, as shown in FIG. 8, the presence or absence of white shading abnormality in the image reading apparatus 1 according to the present embodiment may be detected when the electronic copying apparatus is turned on.
Specifically, when the power of the electronic copying apparatus is turned on, initial setting of each control unit of the electronic copying apparatus including the image reading apparatus 1, for example, an ASIC (Application Specific Integrated Circuit) is performed (Step 31).
After the initial setting, the image reading apparatus 1 performs a reading process of the reference white reading surface 26a of the second reading roller 26 as a white reference member (step 32).
Note that the reading process of the reference white reading surface 26 a is performed over a readable document size area in the image reading apparatus 1.

Next, the image reading apparatus 1 performs level adjustment so that the white level of the read data of the reference white reading surface 26a becomes a predetermined target value (step 34).
Then, the image reading apparatus 1 determines whether or not the white level adjustment processing is completed (step 35).
If the white level adjustment process has not been completed (step 35; N), the image reading apparatus 1 returns to the process of step 32 and repeats the process.
On the other hand, when the white level adjustment processing has been completed (step 35; Y), the image reading apparatus 1 sends the white shading data that has undergone the white level adjustment processing to the min value detection circuit 77 of the abnormality detection circuit 72. input.
Then, the min value detection circuit 77 detects the min value of the white shading data (step 36).

The image reading apparatus 1 determines whether the white shading data is abnormal (step 37).
Specifically, the min value of the white shading data is compared with a preset comparison value in the second comparison circuit 78 to determine whether or not the min value of the white shading data is smaller than the comparison value.
The second comparison circuit 78 determines that the white value of the shading data is normal if the value is larger than the comparison value, and determines that the value is abnormal if the min value of the shading data is smaller than the comparison value. The result is output to the main body control unit 52.
If the white shading data is not abnormal (step 37; N), the abnormality detection process is terminated as it is.

On the other hand, if the white shading data is abnormal (step 37; Y), the abnormality detection circuit 72 determines that there is an abnormality and outputs an abnormality signal to the main body control unit 52.
When an abnormal signal is output to the main body control unit 52, the main body control unit 52 displays a message (alarm) prompting the user to clean it on the operation unit 53 (step 38), and ends the abnormality detection process.
As described above, by performing white shading abnormality detection processing at the time of white level adjustment (at the time of white reference adjustment) performed when the power of the electronic copying apparatus is turned on, the time until the first original image is read (first reading time) Can be shortened, and usability can be further improved. That is, the image reading process (image forming process) can be performed without delaying the first copy time.

In addition, for example, white shading abnormality detection processing is performed before image reading processing (image forming processing) such as at the end of copy processing or when the electronic copying apparatus is turned on, so that cleaning is necessary. However, before the user performs the image reading process (image forming process), it can be notified appropriately. Thereby, useless image formation (copying) processing can be suppressed.
Note that the comparison value (comparison reference value) input to the second comparison circuit 78 of the image reading apparatus 1 according to the present embodiment is configured to be set to an arbitrary value by an input from the operation unit 53, for example. ing. As described above, by allowing the comparison value input to the second comparison circuit 78 to be adjusted, the allowable level of the abnormal image can be arbitrarily set for each user.

1 is a cross-sectional view showing a schematic configuration of an electronic copying apparatus according to an embodiment. It is an enlarged view of a contact image sensor and its peripheral part. FIG. 3 is a block diagram showing electrical connection of a control system in the image reading apparatus according to the present embodiment. It is the block diagram which showed the structure of the white shading correction circuit. 6 is a flowchart showing a procedure of an abnormality detection processing operation during shading correction processing of the image reading apparatus according to the present embodiment. It is the figure which showed the example of detection of white shading data. 6 is a flowchart showing a procedure of an abnormality detection processing operation during shading correction processing of the image reading apparatus according to the present embodiment. 6 is a flowchart showing a procedure of an abnormality detection processing operation during shading correction processing of the image reading apparatus according to the present embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image reader 2 Main body housing | casing 3 1st contact glass 4 2nd contact glass 5 Lamp 6 1st mirror 7 2nd mirror 8 3rd mirror 9 Lens 10 CCD
11 First Reading Unit 20 ADF
DESCRIPTION OF SYMBOLS 21 Document stand 22 Paper feed part 23 Document conveyance path 24 Conveyance roller 25 1st reading roller 26 2nd reading roller 26a Reference | standard white reading surface 27 Contact | adherence image sensor 28 Document discharge part 30 Image formation part 31 Photoconductor 32 Writing unit 33 Developing unit 34 Transfer unit 35 Transport unit 36 Fixing unit 37 Transport switching paper discharge unit 38 Reverse unit 39 Double-sided transport unit 40 Paper feed tray group 41 Side transport unit 42 Paper discharge tray 51 Controller 52 Main body control unit 53 Operation unit 54 Image processing circuit 61 Light source 62 Sensor chip 63 AMP circuit 64 A / D conversion circuit 65 Image processing circuit 66 Frame memory 67 Output control circuit 68 I / F circuit 70 White shading correction circuit 71 Shading data generation circuit 72 Abnormality detection circuit 73 Shading calculation circuit 74 Average Circuit 75 first comparator circuit 76 FIFO
77 min value detection circuit 78 second comparison circuit

Claims (4)

A light source for illuminating the document;
Image data generating means for converting optical document information irradiated by the light source into an electrical signal and generating read image data;
A white reference member serving as a reference for white shading correction of the scanned image;
A shading data generating means for optically reading the white reference member and generating shading data;
Correction means for performing white shading correction on the read image data generated by the image data generation means using the shading data;
Detecting means for detecting the size of the document;
Comparison means for comparing the shading data generated by the shading data generation means with a predetermined reference value;
When the shading data having a value smaller than the predetermined reference value is detected as a result of the comparison by the comparing means, an area where the shading data having a value smaller than the predetermined reference value exists is detected by the detecting means. Determination means for determining whether or not the size area of the detected document image overlaps;
An area where the shading data having a value smaller than the predetermined reference value by the judging means overlaps the size area of the original image detected by the detecting means or the original size area readable by the image reading apparatus. An output means for outputting an abnormal signal when it is determined,
An image reading apparatus comprising:   The image reading apparatus according to claim 1, wherein the predetermined reference value can be set to an arbitrary value.   3. The display device according to claim 1, further comprising a display unit configured to display a warning for prompting cleaning of the white reference member and the image reading unit when the abnormality signal is output by the output unit. Image reading device.   A series of shading data abnormality detection processing is performed by the comparison unit, the determination unit, and the output unit when power is supplied to the image forming apparatus equipped with the image reading apparatus or after the final document reading process. The image reading apparatus according to claim 1, claim 2, or claim 3.

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