JP2002344738A - Image reading device, correction member defect position specifying method, storage medium, and program - Google Patents

Abstract

(57) [Problem] To provide a conventional shading correction circuit of an image reading device without adding a special device, and without adding a new light amount adjusting function to an image reading device having a light amount adjusting function. In addition, an image reading device that can easily detect the presence of a defect included in the shading correction plate,
A correction member defect position specifying method, a storage medium, and a program are provided. SOLUTION: A CPU 25 of the image reading apparatus includes a light source 15.
Is turned on at the first light amount, the line sensor 20 reads the shading correction plate 11 at the first position, stores correction data based on the output of the line sensor 20, turns on the light source 15 at the second light amount, The shading correction plate 11 is read by the line sensor 20 at a second position different from the first position, and the defect position of the shading correction plate 11 is determined from data obtained by correcting the output of the line sensor 20 based on the correction data. Identify.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus, a correction member defect position specifying method, a storage medium, and a program, and more particularly, to shading used for correcting variations in a scanning optical system and the like in an image reading apparatus. The present invention relates to an image reading apparatus, a correction member defect position specifying method, a storage medium, and a program suitable for detecting dust and the like contained in a correction plate.

[0002]

2. Description of the Related Art Conventionally, there is an image reading apparatus which irradiates a document with light and reads an image on the document based on light reflected from the document. The schematic configuration and operation of a general image reading apparatus will be described for convenience with reference to FIGS. 2 and 3 and FIGS.

In the image reading apparatus, a document cover (not shown) for holding the document 12 on the document table is closed on the document table 10 when reading the document. As shown in FIG. 2, light is emitted from below the document 12 by the light source 15 of the reading unit 13. The light reflected on the original surface by the irradiation of the light from the light source 15 enters the line sensor 20 via the lens 14 of the reading unit 13. Line sensor 20
Includes a plurality of CCDs, which are a plurality of photoelectric conversion elements arranged one-dimensionally in the main scanning direction, and each CCD converts received light into an electric signal. As a result, an electric signal corresponding to the image of the document 12 (for one scanning line) is obtained. Manuscript 1
When the scanning for one scanning line 2 is completed, the main scanning motor 6
2, the reading unit 13 is moved in the arrow X direction (main scanning direction) shown in FIG.
Read the scanning line segment. This is repeated to read the entire document 12.

An image signal read from the original 12 by the line sensor 20 is affected by variations in the sensitivity of each CCD of the line sensor 20, fluctuations in dark current, and unevenness in the amount of light due to the optical system. That is, for x number of CCDs constituting the line sensor 20, the light amount of the light source 15 and the CC
When the relationship with the D output is represented in a graph, variations occur as shown in FIG. 10A (n = 1, 2, 3, 4,...).
x). Therefore, eliminating these effects, all x C
In order to match the output characteristics of the CD as shown in FIG. 10B, the output of the CCD is corrected (called shading correction).

[0005] The shading correction is performed as follows. Reading unit 1 by main scanning motor 62
3, the reading unit 13 is set at a position where the shading correction plate 11 provided at the end of the document table 10 can be read. In this state, the output of each CCD of the line sensor 20 obtained when the light source 15 of the reading unit 13 irradiates the shading correction plate 11 with light is stored in the memory as correction data W. Also, the light source 15
The output of each CCD of the line sensor 20 obtained when the light is turned off (or the light is cut off) is stored in the memory as correction data B.

Next, when the image of the document 12 is read by the reading unit 13, the above-mentioned correction data is read from the memory, and based on the correction data, the line sensor 20 is read.
The output data is corrected as shown in the following equation for each CCD.

SD = k.multidot. (SB) / (WB) where S is CCD output data, B is correction data B, W is correction data W, k is a coefficient, and SD is shading correction. Data. In this way, the output unevenness between the CCDs of the line sensor 20 in the reading unit 13 is corrected, and more accurate reading of the document 12 is realized.

[0008]

However, the above-described conventional shading correction method in the image reading apparatus has the following problems. If dust or dust adheres to the shading correction plate 11 of the image reading device, erroneous data will be captured as the correction data W. That is, the shading correction plate 11
In the area where there is a defect to which dust or dust adheres, the output of the CCD of the line sensor 20 decreases due to the defect. Therefore, when the shading correction is performed based on the correction data W, the output of the CCD of the line sensor 20 corresponding to the portion of the shading correction plate 11 to which dust or dust adheres is excessively corrected, and the streak of the read image is corrected. Will appear as unevenness.

For example, as shown in FIG.
Is attached to the shading correction plate 11. The correction data W obtained by reading the shading correction plate 11 to which the dust 9 adheres with the reading unit 13 is shown in FIG.
As shown in FIG. 1B, the output of the CCD of the line sensor 20 decreases at β due to the influence of the dust 9.
In the shading correction, correction is performed using the correction data W so that the corrected data becomes flat for all the CCDs of the line sensor 20, as shown in FIG. That is, conceptually, the reading unit 1
3, when the data as shown in FIG. 11B is read, the read data is multiplied by the data as shown in FIG. 11C, and the flat data as shown in FIG. It can be said that you are trying to get.

If the reading unit 13 reads the document 12 having a uniform density, output data as shown in FIG. 12A is obtained from each CCD of the line sensor 20. Applying shading correction to the output data of each CCD of the line sensor 20 means that the output data of FIG.
Since the data shown in FIG. 11 (C) is multiplied, corrected data as shown in FIG. 12 (C) is obtained. That is, an excessively corrected portion due to dust 9 (FIG. 12)
Due to the influence of (γ) in (B), an uneven portion δ occurs in the corrected data. There is a problem that this appears as streak-like unevenness of the read image.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been developed in an image reading apparatus having a light amount adjusting function without adding a special device to a conventional shading correction circuit of the image reading apparatus. An image reading apparatus, a correction member defect position specifying method, a storage medium, and the like which can easily detect the presence of a defect (dust) included in a shading correction plate without adding a light amount adjustment function.
And to provide programs.

[0012]

In order to achieve the above object, according to the present invention, a correction member having a predetermined reference density is irradiated with light from a light source, and the correction member is illuminated by photoelectric conversion means. An image reading apparatus that has a shading correction function of reading correction data based on the output of the photoelectric conversion unit, storing correction data based on the output of the photoelectric conversion unit, and correcting the output of the photoelectric conversion unit based on the correction data when reading an image of a document. Turning on the light source at a first light amount, reading the correction member at a first position by the photoelectric conversion means, storing correction data based on the output of the photoelectric conversion means, and setting the light source to a second It turns on with the light quantity, reads the correction member by the photoelectric conversion unit at a second position different from the first position, and outputs the output of the photoelectric conversion unit based on the correction data. From data obtained correctly, characterized in that it has a control means for the correction control to identify the defect position of the member.

In order to achieve the above object, the invention according to claim 2 is characterized in that the photoelectric conversion means has a plurality of photoelectric conversion elements arranged one-dimensionally in a main scanning direction, and the correction member has The second light amount is a light amount smaller than the first light amount, and the second position is displaced in a sub-scanning direction orthogonal to the main scanning direction. Position, the defect of the correction member,
It is characterized in that dust or dust adheres to the correction member.

In order to achieve the above object, the invention according to claim 3 is characterized in that the control means is configured to output the predetermined value when the output data of the photoelectric conversion means after shading correction reaches a predetermined value including a maximum value. Wherein the portion of the correction member corresponding to the pixel position is determined to be defective.

According to a fourth aspect of the present invention, when the output data of the photoelectric conversion unit after shading correction exceeds a set level, the control means may control the pixels which have exceeded the set level. The portion of the correction member corresponding to the position is determined as a defect.

In order to achieve the above object, the invention according to claim 5 is characterized in that the control means controls the correction corresponding to an area where a difference between data of adjacent pixels is large in output data of the photoelectric conversion means after shading correction. It is characterized in that a part of the member for use is determined to be defective.

According to a sixth aspect of the present invention, there is provided a copying machine having an image reading function and an image forming function.
The present invention is applied to a facsimile machine having an image reading function / image communication function, and a multifunction machine having a plurality of functions such as an image reading function / image forming function / image communication function.

According to a seventh aspect of the present invention, a light source irradiates a correction member having a predetermined reference density with light, the photoelectric conversion means reads the correction member, and reads the photoelectric conversion member. Correction member defect position executed by an image reading apparatus having a shading correction function for storing correction data based on the output of the means and correcting the output of the photoelectric conversion means based on the correction data when reading an image of a document In a specific method, the light source is turned on at a first light amount, the correction member is read at a first position by the photoelectric conversion unit, and correction data is stored based on an output of the photoelectric conversion unit. The light source is turned on at a second light amount, the correction member is read by the photoelectric conversion unit at a second position different from the first position, and the output of the photoelectric conversion unit From the correction to the data obtained on the basis of the correction data, and identifies a defect position of the correction member.

In order to achieve the above object, the invention according to claim 8, wherein the photoelectric conversion means has a plurality of photoelectric conversion elements arranged one-dimensionally along a main scanning direction, and the correction member comprises The second light amount is a light amount smaller than the first light amount, and the second position is displaced in a sub-scanning direction orthogonal to the main scanning direction. Position, the defect of the correction member,
It is characterized in that dust or dust adheres to the correction member.

According to a ninth aspect of the present invention, when the output data of the photoelectric conversion means after shading correction has reached a predetermined value including a maximum value, a pixel position at the predetermined value is set. A corresponding part of the correction member is determined to be defective.

In order to achieve the above object, the invention according to a tenth aspect is characterized in that, when output data of the photoelectric conversion means after shading correction exceeds a set level, the pixel data corresponding to a pixel position exceeding the set level is output. The correction member is determined to be defective.

In order to achieve the above object, according to the present invention, the correction member corresponding to an area where a difference between data of adjacent pixels is large in output data of the photoelectric conversion means after shading correction. It is characterized by being determined to be defective.

In order to achieve the above object, the invention according to a twelfth aspect provides a copying machine having an image reading function / image forming function, a facsimile apparatus having an image reading function / image communication function, an image reading function / image forming function. The present invention is applied to a multifunction peripheral having a plurality of functions such as a function / image communication function.

According to a thirteenth aspect of the present invention, a light source irradiates a correction member having a predetermined reference density with light, and the correction member is read by a photoelectric conversion means. Correction member defect position executed by an image reading apparatus having a shading correction function for storing correction data based on the output of the means and correcting the output of the photoelectric conversion means based on the correction data when reading an image of a document A computer-readable storage medium storing a program for executing a specifying method, wherein the correcting member defect position specifying method includes: turning on the light source at a first light amount; Reading the member for the first position, storing the correction data based on the output of the photoelectric conversion means, Illuminating the light source with a second light amount, reading the correction member at a second position different from the first position by the photoelectric conversion unit, and outputting the output of the photoelectric conversion unit to the correction unit. Specifying a defect position of the correction member from data obtained by correction based on the data.

According to a fourteenth aspect of the present invention, there is provided an image forming apparatus, wherein the photoelectric conversion means comprises one photoelectric conversion means along the main scanning direction.
It has a plurality of dimensionally arranged photoelectric conversion elements, the correction member has a length over the entire area in the main scanning direction, the second light amount is a light amount smaller than the first light amount,
The second position is a position displaced in a sub-scanning direction orthogonal to the main scanning direction, and the defect of the correction member is a state in which dust or dust adheres to the correction member. Features.

In order to achieve the above object, the invention according to claim 15 is characterized in that the correction member defect position specifying method is such that the output data of the photoelectric conversion means after shading correction has a predetermined value including a maximum value. And a step of determining a portion of the correction member corresponding to the pixel position having the predetermined value as a defect.

In order to achieve the above object, the invention according to claim 16 is characterized in that the correction member defect position specifying method is characterized in that when the output data of the photoelectric conversion means after shading correction exceeds a set level, Determining a portion of the correction member corresponding to a pixel position exceeding the level as a defect;

In order to achieve the above object, the invention according to a seventeenth aspect is characterized in that the correction member defect position specifying method is arranged such that the output data of the photoelectric conversion means after shading correction has a large difference between data of adjacent pixels. The step of judging a portion of the correction member corresponding to the above as a defect is provided.

To achieve the above object, the invention according to claim 18 provides a copying machine having an image reading function and an image forming function, a facsimile apparatus having an image reading function and an image communication function, an image reading function and an image forming function. It is characterized by being readable by a computer storing a program for executing the correction member defect position specifying method executed by a multifunction peripheral having a plurality of functions such as a function / image communication function.

In order to achieve the above object, the invention according to claim 19 irradiates light from a light source to a correction member having a predetermined reference density, reads the correction member by photoelectric conversion means, and reads the correction member. A program supplied to an image reading apparatus having a shading correction function for storing correction data based on an output of the means and correcting an output of the photoelectric conversion means based on the correction data when reading an image of a document, Lighting the light source at a first light amount, reading the correction member at a first position by the photoelectric conversion means, storing correction data based on an output of the photoelectric conversion means, Turning on the light source with a second light amount, and reading the correction member at a second position different from the first position by the photoelectric conversion means. A step that outputs from the correction to the data obtained on the basis of the correction data of the photoelectric conversion means, characterized by storing and identifying the defect position of the correction member.

According to a twentieth aspect of the present invention, in order to achieve the above-mentioned object, the photoelectric conversion means may include one or more photo-electric conversion means along the main scanning direction.
It has a plurality of dimensionally arranged photoelectric conversion elements, the correction member has a length over the entire area in the main scanning direction, the second light amount is a light amount smaller than the first light amount,
The second position is a position displaced in a sub-scanning direction orthogonal to the main scanning direction, and the defect of the correction member is a state in which dust or dust adheres to the correction member. Features.

According to a twenty-first aspect of the present invention, when the output data of the photoelectric conversion means after shading correction reaches a predetermined value including a maximum value, the pixel position at the predetermined value A step of determining a corresponding portion of the correction member as a defect is stored.

In order to achieve the above object, according to the present invention, when the output data of the photoelectric conversion means after the shading correction exceeds a set level, the pixel data corresponding to the pixel position exceeding the set level is output. A step of determining a portion of the correction member as a defect is stored.

In order to achieve the above object, according to the twenty-third aspect of the present invention, in the output data of the photoelectric conversion means after shading correction, a portion of the correction member corresponding to a region where a difference between data of adjacent pixels is large is provided. A step of determining a defect is stored.

In order to achieve the above object, an invention according to claim 24 is a copying machine having an image reading function / image forming function, a facsimile apparatus having an image reading function / image communication function, an image reading function / image forming function. It is provided to a multifunction peripheral having a plurality of functions such as a function and an image communication function.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing embodiments of the present invention, an outline of the present invention will be described.

According to the present invention, a plurality of line sensors having a plurality of photoelectric conversion elements arranged one-dimensionally in the main scanning direction provided in an image reading apparatus have a uniform reference density in the main scanning direction. Read a shading correction plate having a length over the entire area, store correction data based on the output of each photoelectric conversion element, and when reading an image of a document, output the output of each photoelectric conversion element based on the correction data. In the shading correction method for correcting, a means for changing the light amount of the light source illuminating the original is provided, the light source is turned on at the first light amount, the shading correction plate is read at the first position by the line sensor, and each photoelectric conversion element is The correction data is stored based on the output, the light source is turned on at the second light amount, and the shading correction plate is moved by the line sensor to a position different from the first position. Reading at a second position, in which the outputs of the photoelectric conversion element from the data obtained by correcting, based on the correction data, to identify the position of the defect (dirt or dust) the shading correction plate.

In this case, without changing the light amount of the light source,
After storing the data for shading correction at the first position, the shading correction plate is read again by the line sensor at the second position displaced in the sub-scanning direction from the first position, and from the obtained data, It is also possible to specify the position of a defect (dust or dust) of the shading correction plate. However, the density of the shading correction plate is sufficiently white, and in many cases, there is little difference between data of a portion where dust is not present and data of a portion where dust is present. That is, δ in FIG. 12C is not conspicuous.
Therefore, when creating shading correction data and when actually reading the shading correction plate,
By changing the light amount of the light source and making δ stand out,
This is to make it easier to detect the position of dust or dust attached to the shading correction plate.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a sectional view showing the structure of the image reading apparatus (scanner) according to the embodiment of the present invention, focusing on the scanning optical system such as the image sensor unit. The image reading apparatus includes a document table 10, a shading correction plate 11, and a reading unit 13 in each part of the housing 1. Further, the reading unit 13 includes the self-focusing lens array 1.
4, a light source 15 and a color line sensor (image sensor) 20.

More specifically, a document table 10 made of colorless and transparent glass is provided on the upper surface of the housing 1. Is placed. A shading correction plate 11 having a uniform reference density, a sufficiently white density, and a length over the entire area in the main scanning direction is provided on the lower surface side of the end of the document table 10.

The reading unit 13 is configured to be movable via a scanning mechanism described later, and reads an image from the document 12. That is, the light source 15 of the reading unit 13
2 is irradiated with light, and the reflected light from the document 12 enters the line sensor 20 via the self-focusing lens array 14. The line sensor 20 includes a plurality of CCDs, which are a plurality of photoelectric conversion elements arranged one-dimensionally in the main scanning direction, and converts reflected light from the document 12 into an electric signal by each CCD. At the time of shading correction, the output of the CCD of the line sensor 20 is corrected (shading correction) by reading the shading correction plate 11 by the reading unit 13.

FIG. 3 is a block diagram of the embodiment shown in FIG.
FIG. 3 is a perspective view illustrating an appearance of a scanning mechanism of the image reading apparatus (scanner) illustrated in FIG. The scanning mechanism of the image reading apparatus includes a carriage 60, a main scanning guide 61, a main scanning motor 62, a main scanning belt 63, pulleys 64 and 67, a sub scanning guide 65,
A sub-scanning belt 66 and a sub-scanning motor (not shown) are provided.

In detail, the main scanning guide 61 is disposed inside the carriage 60 along the longitudinal direction of the carriage 60, and the main scanning motor 62 is disposed on the side wall of the carriage 60. Have been. A pulley 67 is fixed to the drive shaft of the main scanning motor 62, and a pulley 64 that is paired with the pulley 67 is disposed at a predetermined distance from the pulley 67 in the longitudinal direction of the carriage 60. I have. An endless main scanning belt 63 is wound between the pulleys 64 and 67 in parallel with the main scanning guide 61. The main scanning guide 61 is provided inside the reading unit 13.
And the end of the reading unit 13 is fixed to a part of the main scanning belt 63. A sub-scanning guide 65 penetrates the end of the carriage 60,
The lower surface of the end of the carriage 60 is fixed to a part of the sub-scanning belt 66.

When the main scanning motor 62 is driven to rotate, the pulley 67 fixed to the drive shaft of the main scanning motor 62 is driven to rotate, so that the main scanning belt 63 is circulated between the pulleys 64 and 67. Thereby, the reading unit 13
By moving in the direction of the arrow X (main scanning direction) in the figure along the main scanning guide 61, reading in the main scanning direction is performed.
On the other hand, when a sub-scanning motor (not shown) is driven to rotate, the sub-scanning belt 66 is driven. Thereby, the carriage 6
0 moves in the arrow Y direction (sub-scanning direction) in the figure along the sub-scanning guide 65 to perform sub-scanning movement.

FIG. 1 is a block diagram showing a schematic configuration of a signal processing system of an image reading apparatus according to an embodiment of the present invention. The signal processing system of the image reading device includes a line sensor 20, an amplifier 21, an A / D converter 22, a shading correction circuit 23, an image processing circuit 24, a CPU 25, and a W-RAM 26.
It has.

The above configuration will be described in detail.
Includes a plurality of CCDs, which are a plurality of photoelectric conversion elements arranged one-dimensionally in the main scanning direction, as described above.
The reflected light from the original is converted into an electric signal by the CD. The amplifier 21 amplifies the output signal of the line sensor 20.
The A / D converter 22 converts an analog signal output from the amplifier 21 into a digital signal. The shading correction circuit 23 performs shading correction (for the line sensor 2).
0 CCD output correction). The image processing circuit 24
The output signal of the shading correction circuit 23 is subjected to known image processing and output to an external device (not shown) connected to the image reading device.

The CPU 25 is a central processing unit for controlling each part of the image reading apparatus, and executes the processing shown in the flowchart of FIG. 9 based on a program for executing the correction member defect position specifying method of the present invention. That is, the CPU 25
Turns on the light source 15 at the first amount of light,
To read the shading correction plate 11 at the first position, store the correction data based on the output of the line sensor 20, turn on the light source 15 with a second light amount smaller than the first light amount, and perform shading by the line sensor 20. The correction plate 11 is read at a second position displaced in the sub-scanning direction different from the first position, and a shading correction plate is obtained from data obtained by correcting the output of the line sensor 20 based on the correction data. Control is performed to specify 11 defect positions. The W-RAM 26 is a memory for storing shading correction data and the like.

The program for executing the correction member defect position specifying method of the present invention may be stored in advance in an internal memory of the CPU 25 of the image reading apparatus, or may be stored in a ROM (not shown) of the image reading apparatus. The configuration may be stored in advance, or the configuration may be such that an external device such as an information processing device supplies the image reading device. The first light amount and the second light amount of the light source 15 and the first position and the second position of the shading correction plate 11 are defect position specifying related information for specifying a defect position of the shading correction plate 11. Is stored in advance in the internal memory of the CPU 25 of the image reading apparatus or in a ROM (not shown).

Next, the shading correction plate 11 of the image reading apparatus constructed as described above according to the embodiment of the present invention.
About the method of detecting dust or dust attached to
This will be described in detail with reference to FIGS.

First, the flow of the process for detecting dust or dust attached to the shading correction plate 11 of the image reading apparatus will be described with reference to the flowchart of FIG. Note that the flowchart of FIG. 9 shows that the CPU 25 of the image reading apparatus executes the reading unit 13 and the shading correction circuit 2 based on a program for executing the correction member defect position specifying method of the present invention.
3. It is executed by controlling the scanning mechanism (FIG. 3) and the like.

Assume that dust or dust 9 as shown in FIG. 4A has adhered to the shading correction plate 11. At the time of shading correction, the light source 15 of the reading unit 13 is turned on at a preset first light amount (step S1), and the shading correction plate 11 having a defect due to dust or dust 9 is moved to the first position. When read by the line sensor 20 (step S2), FIG.
As shown in (B), data in which the output of the CCD corresponding to the portion of dust or dust 9 is reduced is obtained. In order to convert the data of which the output of the CCD corresponding to the dust or dust 9 is reduced to constant data as shown in FIG. 4D, a γ portion (dust or dust) as shown in FIG. The shading correction data in which the portion (corresponding to the dust 9) protrudes is obtained and stored in the W-RAM 26 (step S3).

Next, assuming that the position of the shading correction plate 11 in the sub-scanning direction is changed and read again by the line sensor 20, the output of the CCD corresponding to the portion where the dust or dust 9 exists is the output of the other CCD. Brighter than. If this bright part can be detected,
The position of dust or dust 9 attached to the shading correction plate 11 can be detected. However, as described above, the density of the shading correction plate 11 is sufficiently white, and in many cases, little difference is recognized between data of a portion where dust or dust 9 does not exist and data of a portion where dust or dust 9 exists. That is, δ shown in FIG.
But small and inconspicuous.

Then, after obtaining the shading correction data as described above, the light source 15 of the reading unit 13 is turned on with a preset second light amount smaller than the first light amount (step S4), and the shading correction is performed. The plate 11 is read by the line sensor 20 at a second position displaced in the sub-scanning direction from the first position (step S5), and shading correction is performed. Then, even if the shading correction plate 11 having the same density is read, the light amount of the light source 15 is small (second light amount) as compared with before the light amount of the light source 15 is changed (first light amount) as shown in FIG. In addition, the output level of the data obtained after shading correction is
It becomes low as shown by the arrow in the figure.

However, the data after shading correction on the portion of the shading correction plate 11 where dust or dust 9 is present is the same as the data when the shading correction plate 11 is read and the shading correction is performed without changing the light amount of the light source 15. No big difference. For this reason, the presence of dust or dust 9 on the shading correction plate 11 becomes remarkable, and the position of the dust or dust 9 on the shading correction plate 11, that is, the detection of the dust or dust 9 can be facilitated (step). S6).

Next, various defect position specifying methods for detecting dust or dust attached to the shading correction plate 11 of the image reading apparatus will be described with reference to FIGS.

First defect position specifying method (FIG. 6): C of line sensor 20 after shading correction of a portion of shading correction plate 11 where dust or dust exists.
Since the output data of the CD often has the maximum value of the output range, the portion of the shading correction plate 11 corresponding to the pixel having the maximum value has no dust or dust attached to the shading correction plate 11. to decide.

Second defect position specifying method (FIG. 7): C of line sensor 20 after shading correction of a portion of shading correction plate 11 where dust or dust exists.
Since the output data of the CD has a sufficiently large output level as compared with the output data of the CCD after shading correction of the portion where no dust or dust is present, the density data of the shading correction plate 11 is checked in advance, and The output level is set with a certain margin in the data, and the portion of the shading correction plate 11 corresponding to the output data of the CCD exceeding the set output level is determined to be dust or dust attached to the shading correction plate 11.

Third defect position specifying method (FIG. 8): C of line sensor 20 after shading correction of a portion of shading correction plate 11 where dust or dust exists.
Since the output data of the CD has a sufficiently large level as compared with the output data of the CCD after shading correction of a portion where no dust or dust is present (see FIG. 8A), the data of adjacent pixels is successively changed. By examining all the areas, all the areas where the data difference is sandwiched between the pixel having a large value in the plus direction and the pixel having a large difference in the minus direction (FIG. 8B
(See FIG. 3) is determined to be dust or dust attached to the shading correction plate 11.

As described above, according to the embodiment of the present invention, light is emitted from the light source 15 to the shading correction plate 11, and the shading correction plate 11 is read by the line sensor 20, and the output of the line sensor 20 is output. In an image reading apparatus having a shading correction function of storing correction data based on the correction data based on the correction data and reading the output of the line sensor 20 when reading the image of the document, the CPU 25 turns on the light source 15 at the first light amount. Then, the shading correction plate 11 is
Is read at the first position, the correction data based on the output of the line sensor 20 is stored, the light source 15 is turned on at a second light amount smaller than the first light amount, and the shading correction plate 11 is From the data obtained by reading at the second position displaced in the sub-scanning direction different from the first position and correcting the output of the line sensor 20 based on the correction data, the defect position of the shading correction plate 11 is obtained. Since the specified control is performed, the following effects are obtained.

The shading correction plate 11 can be used without adding a special device to the conventional shading correction circuit of the image reading apparatus and without adding a new light amount adjustment function to the image reading apparatus having the light amount adjustment function. It is possible to easily detect the presence of a defect (dust or dust) included in the image.

[Other Embodiments] In the above embodiment of the present invention, the case where the defect detection of the shading correction plate is applied to an image reading apparatus (scanner) has been described as an example. However, the present invention is not limited to this. Rather than having a plurality of functions such as a copier having an image reading function / image forming function, a facsimile machine having an image reading function / image communicating function, and an image reading function / image forming function / image communicating function, etc. Of course, it is also possible to apply to a multifunction machine.

In the above-described embodiment of the present invention, the case of using only the image reading apparatus has been described as an example. However, the present invention is not limited to this. It can also be applied to a system in which devices are connected, or a system in which an arbitrary number of peripheral devices including an image reading device, a copier, a multifunction device, or a facsimile device, and an arbitrary number of information processing devices such as a personal computer are connected to a network. Of course it is possible.

The present invention may be applied to a system composed of a plurality of devices or to an apparatus composed of one device. A medium such as a storage medium storing program codes of software for realizing the functions of the above-described embodiments is supplied to a system or an apparatus, and a computer (or CPU or MPU) of the system or the apparatus stores the medium in the medium such as a storage medium. Needless to say, this can also be achieved by reading and executing the program code thus executed.

In this case, the program code itself read from a medium such as a storage medium realizes the functions of the above-described embodiment, and the medium such as a storage medium storing the program code constitutes the present invention. Will be. Examples of a medium such as a storage medium for supplying the program code include a floppy (registered trademark) disk, a hard disk, an optical disk, a magneto-optical disk, and a CD-RO.
M, CD-R, magnetic tape, nonvolatile memory card,
ROM or download via a network can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS and the like running on the computer are actually executed based on the instructions of the program code. It goes without saying that a part or all of the above-described processing is performed, and the functions of the above-described embodiments are realized by the processing.

Further, after the program code read from a medium such as a storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the program code is read out. It is needless to say that a CPU or the like provided in the function expansion board or the function expansion unit performs part or all of the actual processing based on the above, and the functions of the above-described embodiments are realized by the processing.

[0068]

As described above, according to the image reading apparatus of the present invention, the light source is turned on at the first light amount, the correction member is read at the first position by the photoelectric conversion means, and the photoelectric conversion means is turned on. The correction data based on the output is stored, the recording light source is turned on at a second light amount smaller than the first light amount, and the correction member is read by a photoelectric conversion unit at a second position different from the first position. In order to perform control for specifying the defect position of the correction member from the data obtained by correcting the output of the photoelectric conversion means based on the correction data, a special device is added to the conventional shading correction circuit of the image reading device. Without adding a new light amount adjusting function to the image reading apparatus having the light amount adjusting function, the presence of a defect (dust or dust) included in the correction member for shading correction can be detected. It is possible to be facilitated.

Also, in the correction member defect position specifying method of the present invention, the storage medium of the present invention, and the program of the present invention, similarly to the above, without adding a special device or function to the image reading apparatus, It is possible to easily detect the presence of a defect (dust or dust) included in the shading correction member.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a signal processing system of an image reading apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a structure centering on a scanning optical system of the image reading apparatus according to the embodiment of the present invention.

FIG. 3 is a perspective view showing an appearance of a scanning mechanism of the image reading apparatus according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a shading correction plate of the image reading device according to the embodiment of the present invention and output data of the CCD when reading the shading correction plate. FIG. 4B is an explanatory view showing a state in which the CCD output is attached, FIG.
(C) is an explanatory diagram showing data in which the CCD output of a portion corresponding to dust or dust is protruded, and (D) is an explanatory diagram showing CCD output data that has become constant.

FIG. 5 is an explanatory diagram showing a state in which the output level of CCD output data obtained after shading correction is low in the image reading apparatus according to the embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a relationship between a CCD position and CCD output data based on a first dust or dust detection method in the image reading apparatus according to the embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a relationship between a CCD position and CCD output data based on a second dust or dust detection method in the image reading apparatus according to the embodiment of the present invention.

8A and 8B are explanatory diagrams based on a third dust or dust detection method in the image reading apparatus according to the embodiment of the present invention, and FIG. 8A is an explanatory diagram showing a relationship between a CCD position and CCD output data; (B) is an explanatory diagram showing the relationship between the position of the CCD and the amount of change in the CCD output data.

FIG. 9 is a flowchart illustrating a dust or dust detection process of the shading correction plate of the image reading apparatus according to the embodiment of the present invention.

10A and 10B are explanatory diagrams illustrating output characteristics of a line sensor of an image reading apparatus according to a conventional example, in which FIG. 10A is a diagram illustrating the relationship between the light amount of a light source and the output of each CCD, and FIG. C
FIG. 3 is an explanatory diagram showing a state where output characteristics of a CD are matched.

FIG. 11 shows a shading correction plate of an image reading apparatus according to a conventional example and a CCD for reading the shading correction plate.
7A is an explanatory diagram showing output data of the shading correction plate, and FIG. 8B is an explanatory diagram showing a state where dust or dust adheres to the shading correction plate. FIG.
FIG. 8C is an explanatory diagram showing data with a reduced D output, FIG. 9C is an explanatory diagram showing data in which the CCD output of a portion corresponding to dust or dust is protruded, and FIG. 9D is an explanatory diagram showing flat CCD output data.

12A and 12B are explanatory diagrams showing output data of a CCD when an original is read by an image reading apparatus according to a conventional example, and FIG.
FIG. 4 is an explanatory diagram showing CD output data, FIG. 4B is an explanatory diagram showing multiplied data at the time of shading correction, and FIG. 4C is an explanatory diagram showing shading corrected data.

[Explanation of symbols]

 Reference Signs List 11 Shading correction plate (correction member) 15 Light source 20 Line sensor (photoelectric conversion means) 23 Shading correction circuit 25 CPU (control means) 26 W-RAM

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5B047 BB02 DA04 DA06 DC01 DC09 EA07 5C072 AA01 BA08 BA17 EA05 FB12 RA20 UA02 UA20 XA01 5C077 LL02 MM03 PP06 PP44 PP45 PP51 PQ24

Claims (24)

[Claims] 1. A light source irradiates a correction member having a predetermined reference density with light, reads the correction member by photoelectric conversion means, stores correction data based on the output of the photoelectric conversion means, and stores a document. An image reading apparatus having a shading correction function of correcting an output of the photoelectric conversion unit based on the correction data when reading an image, wherein the light source is turned on at a first light amount, and the correction is performed by the photoelectric conversion unit. The member for reading is read at the first position, the correction data is stored based on the output of the photoelectric conversion unit, the light source is turned on at a second light amount, and the correction member is converted to the first member by the photoelectric conversion unit. A defect position of the correction member is specified from data obtained by reading at a second position different from the position and correcting the output of the photoelectric conversion unit based on the correction data. Image reading apparatus characterized by having a control means for performing control. 2. The photoelectric conversion unit has a plurality of photoelectric conversion elements arranged one-dimensionally along a main scanning direction, the correction member has a length over the entire area of the main scanning direction,
The second light amount is a light amount smaller than the first light amount, the second position is a position displaced in a sub-scanning direction orthogonal to the main scanning direction, and a defect of the correction member. 2. The image reading apparatus according to claim 1, wherein dust or dust adheres to the correction member. 3. The correction unit according to claim 1, wherein when the output data of the photoelectric conversion unit after the shading correction reaches a predetermined value including a maximum value, the control unit corresponds to a portion of the correction member corresponding to a pixel position at the predetermined value. The image reading apparatus according to claim 1, wherein the image reading device determines that the image is defective. 4. When the output data of the photoelectric conversion unit after shading correction exceeds a set level, the control unit sets a part of the correction member corresponding to a pixel position exceeding the set level as a defect. The image reading apparatus according to claim 1, wherein the determination is performed. 5. The control unit determines that a portion of the correction member corresponding to a region where a difference between data of adjacent pixels is large in output data of the photoelectric conversion unit after shading correction is a defect. The image reading device according to claim 1. 6. A copying machine having an image reading function / image forming function, a facsimile machine having an image reading function / image communicating function, and a plurality of functions such as an image reading function / image forming function / image communicating function. The image reading apparatus according to claim 1, wherein the image reading apparatus is applied to a multifunction peripheral. 7. A light source irradiates a correction member having a predetermined reference density with light, reads said correction member by photoelectric conversion means, stores correction data based on an output of said photoelectric conversion means, and stores a document. A correction member defect position specifying method executed by an image reading apparatus having a shading correction function of correcting an output of the photoelectric conversion unit based on the correction data when reading an image. The correction member is read at the first position by the photoelectric conversion means, the correction data is stored based on the output of the photoelectric conversion means, the light source is turned on at the second light amount, and the photoelectric conversion is performed. Means for reading the correction member at a second position different from the first position and correcting the output of the photoelectric conversion means based on the correction data. Al, the correction member defect position specifying method characterized by identifying a defect position of the correction member. 8. The photoelectric conversion unit has a plurality of photoelectric conversion elements arranged one-dimensionally in a main scanning direction, the correction member has a length over the entire area in the main scanning direction,
The second light amount is a light amount smaller than the first light amount, the second position is a position displaced in a sub-scanning direction orthogonal to the main scanning direction, and a defect of the correction member. 8. The correction member defect position specifying method according to claim 7, wherein dust or dust is attached to the correction member. 9. When the output data of the photoelectric conversion means after shading correction reaches a predetermined value including a maximum value,
8. The method according to claim 7, wherein a portion of the correction member corresponding to the pixel position having the predetermined value is determined as a defect. 10. When the output data of the photoelectric conversion means after shading correction exceeds a set level, a portion of the correction member corresponding to a pixel position exceeding the set level is determined to be defective. 8. The method according to claim 7, wherein the position of the correction member defect is specified. 11. The correction member according to claim 7, wherein, in the output data of the photoelectric conversion unit after the shading correction, a portion of the correction member corresponding to a region where a difference between data of adjacent pixels is large is determined as a defect. Correction member defect position specifying method. 12. A copying machine having an image reading function / image forming function, a facsimile machine having an image reading function / image communicating function, and a plurality of functions such as an image reading function / image forming function / image communicating function. The correction member defect position specifying method according to claim 7, wherein the method is applied to a multifunction peripheral. 13. A light source irradiates a correction member having a predetermined reference density with light, reads said correction member by photoelectric conversion means, and stores correction data based on an output of said photoelectric conversion means. A computer storing a program for executing a correction member defect position specifying method executed by an image reading apparatus having a shading correction function for correcting the output of the photoelectric conversion means based on the correction data when reading an image. The correction member defect position specifying method, wherein the step of turning on the light source at a first light amount; the step of reading the correction member at a first position by the photoelectric conversion means; Storing the correction data based on the output of the photoelectric conversion means, turning on the light source at a second light amount, Reading the correction member at a second position different from the first position by photoelectric conversion means, and performing the correction from data obtained by correcting the output of the photoelectric conversion means based on the correction data. Specifying a defect position of the member for use. 14. The photoelectric conversion unit has a plurality of photoelectric conversion elements arranged one-dimensionally in a main scanning direction, the correction member has a length extending over the entire area in the main scanning direction, The second light amount is a light amount smaller than the first light amount, the second position is a position displaced in a sub-scanning direction orthogonal to the main scanning direction, and the defect of the correction member is 14. The storage medium according to claim 13, wherein dust or dust adheres to said correction member. 15. The correction member defect position specifying method according to claim 15,
When the output data of the photoelectric conversion unit after shading correction has reached a predetermined value including a maximum value, a step of determining a portion of the correction member corresponding to a pixel position at the predetermined value as a defect. 14. The storage medium according to claim 13, wherein: 16. The correction member defect position specifying method,
When the output data of the photoelectric conversion unit after shading correction exceeds a set level, a step of determining a portion of the correction member corresponding to a pixel position exceeding the set level as a defect is provided. The storage medium according to claim 13. 17. The correction member defect position specifying method,
14. The storage according to claim 13, further comprising a step of determining a portion of the correction member corresponding to a region where a difference between data of adjacent pixels is large in output data of the photoelectric conversion unit after shading correction as a defect. Medium. 18. A copying machine having an image reading function / image forming function, a facsimile machine having an image reading function / image communicating function, and a plurality of functions such as an image reading function / image forming function / image communicating function. The storage medium according to any one of claims 13 to 17, wherein the storage medium is readable by a computer storing a program for executing the correction member defect position specifying method executed by the multifunction peripheral. 19. A light source irradiates a correction member having a predetermined reference density with light, reads the correction member by photoelectric conversion means, and stores correction data based on an output of the photoelectric conversion means. A program supplied to an image reading apparatus having a shading correction function of correcting the output of the photoelectric conversion unit based on the correction data when reading the image, wherein the light source is turned on at a first light amount; Reading the correction member at a first position by the photoelectric conversion unit, storing correction data based on an output of the photoelectric conversion unit, and turning on the light source with a second light amount; Reading the correction member at a second position different from the first position by photoelectric conversion means; and From the correction to the data obtained on the basis of the Tadashiyo data, program characterized by storing and identifying the defect position of the correction member. 20. The photoelectric conversion unit includes a plurality of photoelectric conversion elements arranged one-dimensionally along a main scanning direction, wherein the correction member has a length extending over the entire area in the main scanning direction. The second light amount is a light amount smaller than the first light amount, the second position is a position displaced in a sub-scanning direction orthogonal to the main scanning direction, and the defect of the correction member is 20. The program according to claim 19, wherein dust or dust adheres to the correction member. 21. When the output data of the photoelectric conversion means after shading correction reaches a predetermined value including a maximum value, a portion of the correction member corresponding to a pixel position at the predetermined value is determined to be defective. The program according to claim 19, wherein steps are stored. 22. When the output data of the photoelectric conversion means after the shading correction exceeds a set level, a step of determining a portion of the correction member corresponding to a pixel position exceeding the set level as a defect is stored. 20. The program according to claim 19, wherein the program is executed. 23. A step of determining a portion of the correction member corresponding to a region where a difference between data of adjacent pixels is large in output data of the photoelectric conversion unit after shading correction is a defect. Claim 19
The described program. 24. A copying machine having an image reading function / image forming function, a facsimile machine having an image reading function / image communicating function, and a plurality of functions such as an image reading function / image forming function / image communicating function. 24. The program according to claim 19, wherein the program is supplied to a multifunction peripheral.