JP2002325166A - Image reader, its control method and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader that can accurately read an original image even when the image reader reads the original image while a document automatic feed means is feeding the original to the image reader and to provide its control method and a storage medium. SOLUTION: When an original is set to an original feed tray of the automatic document feeder and start of copying is instructed, shading correction data of one line are read and a shading correction coefficient obtained by an arithmetic operation is set to a coefficient memory (steps S1-S3). Then skimming- through of the original is started (step S4), a distance between the original and a xenon tube lamp in a mirror unit is calculated depending on a signal from a sensor placed at a prescribed position of the automatic document feeder, the shading correction coefficient is corrected in real time by each line depending on the calculated distance (step S5), and a memory stores original image data processed based on the shading correction coefficient after the correction (S6).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image reading apparatus having an automatic document feeder for reading an image of a document sent by the automatic document feeder, a control method thereof, and a storage medium.

[0002]

2. Description of the Related Art Conventionally, a copying machine has been known as an image reading apparatus which includes an automatic document feeder and reads an image of a document sent by the automatic document feeder.

In such a copying machine, a document is moved to and placed on a platen glass of a reading device by an automatic document feeder, and then a mirror unit equipped with an illumination light source is moved onto the platen glass. I was trying to read an image.

In recent years, however, in order to increase the number of originals read per unit time, a mirror unit is fixed at a predetermined position, and an original image is read while an original is being fed to a reading device by an automatic original feeder. Is being adopted.

FIG. 1 is a cross-sectional view showing the structure of a color copying machine employing such a flow reading system.

Referring to FIG. 1, the color copying machine mainly includes an automatic document feeder 200, an image scanner unit 201, and a printer unit 202.

The automatic document feeder 200 feeds a document to the image scanner unit 201.

[0008] The image scanner unit 201 reads a document and performs digital signal processing.

The printer unit 202 prints out an image corresponding to the original image read by the image scanner unit 201 on recording paper in full color.

In the image scanner section 201, the original 204 on the original platen glass 203 is a xenon lamp 2
05, and reflected light from the original is reflected by the reflection mirror 2
06 and 207, and an image is formed on the three-line sensor 210 by the lens 209. 3 line sensor 210
Is full color information from reflected light, red (R)
Components, a green (G) component, and a blue (B) component, respectively.
Send to 1.

The signal processing section 211 performs predetermined signal processing on the transmitted electric signals and outputs the processed signals to the printer section 202. The printer unit 202 forms a copy image of the document based on this signal.

The speed of the first mirror unit 208 having the xenon tube lamp 205 and the reflecting mirror 206 is v, and the speed of the second mirror unit 2071 having the reflecting mirror 207 is v / 2. The entire surface of the document is scanned by being driven by a motor (not shown) in a direction perpendicular to the target scanning direction.

When the original is read by the automatic document feeder 200 using the automatic document feeder 200, the first mirror unit 208 is held below the document reading glass 14 and the original is read. , Continuous reading of a document can be realized in a short time.

FIG. 10 is a cross-sectional view showing the structure of the automatic document feeder 200, and FIG. 11 is a view for explaining how the document 204 is fed by the automatic document feeder 200.

In FIG. 11, when the original 204 is placed on the original feed tray 9 and the reading operation of the original is started, the feed roller 8 is lowered onto the original 204 ((a)), and the original 20 is moved.
4 is picked up, and the document 204 is conveyed to the lower registration roller 3 and the upper registration roller 4 by rotation of the conveyance roller 6. In the lower registration roller 3 and the upper registration roller 4, a loop is formed in the sheet, and the skew of the sheet is corrected ((b)).

Next, the document 204 is pressed against the large conveying roller 1 by the roller 2 and is conveyed in accordance with the rotation of the large conveying roller 1, and the small lead roller 13 prevents the document 204 from separating from the large conveying roller 1. ((C)).

Next, the original 204 is conveyed on the flow reading original reading glass 14 to read the original image, and the original 204 is discharged while preventing the original 204 from being separated from the conveying roller 1 by the large lead roller 12. The sheet is conveyed to the upper roller 11 and the lower discharge roller 10 ((d)).

Next, the document 204 is discharged to the discharge tray 15 by the upper discharge roller 11 and the lower discharge roller 10 ((e)).

The roller 2, the small lead roller 13 and the large lead roller 12 are pressed against the large transfer roller 1 with a predetermined pressure by a spring (not shown).

The large transport roller 1 is pressed against the original reading glass 14 with a predetermined pressure by a spring (not shown) so as to absorb a shock when the original 204 collides with the original reading glass 14. I have.

Here, the case where one document is read has been described. However, when reading a plurality of documents continuously, the same operation is repeated repeatedly with a predetermined interval between each document transport.

[0022]

However, in the above-mentioned conventional image reading apparatus, when the original is read by the flow reading method, the large transport roller 1 pressed against the flow reading original reading glass 14 by the spring is moved by the waist of the original. Since the distance fluctuates up and down, the distance between the original and the light source that illuminates the original fluctuates, and as a result, the amount of light illuminating the original fluctuates, and the original image may not be accurately read. Specifically, when the transport roller large 1 is displaced upward and the distance between the light source and the document is large, the document image is read darker than it actually is.

The present invention has been made by paying attention to this point. Even when the original image is read while the original is sent to the image reading apparatus by the automatic document feeder, the original image can be read accurately. It is an object to provide an image reading device, a control method thereof, and a storage medium.

[0024]

According to a first aspect of the present invention, there is provided an image reading apparatus, comprising: an automatic document feeder for automatically feeding a document to a position where an image written on the document is read; An image reading device for reading an image of a document being conveyed by the automatic document conveyance means, wherein the light irradiation means irradiates light to the document being conveyed by the automatic document conveyance means; Photoelectric conversion means for receiving light reflected from a document and converting the converted signal into an electric signal; processing means for performing signal processing on the converted electric signal; and a distance between the document being conveyed and the light irradiation means. And a correcting means for correcting a predetermined signal processing of the signal processing according to the measured distance.

According to a second aspect of the present invention, in the image reading apparatus of the first aspect, the predetermined signal processing is shading correction processing.

According to a third aspect of the present invention, in the image reading apparatus according to the second aspect, the correction means comprises:
A shading correction coefficient used in the shading correction processing is corrected.

According to a fourth aspect of the present invention, there is provided a method for controlling an image reading apparatus, comprising: an automatic document feeder for automatically feeding a document to a position where an image written on the document is read; In a control method for controlling an image reading device that reads an image of a document being conveyed by an automatic document conveyance device, a light irradiation step of irradiating light to a document being conveyed by the automatic document conveyance device with a light irradiation device; Processing the electric signal converted by the photoelectric conversion means for receiving the light reflected from the original in accordance with the received light and converting the light into an electric signal; A correction step of correcting a predetermined signal processing of the signal processing according to the distance measured by the measuring means for measuring the distance to the means. And butterflies.

According to a fifth aspect of the present invention, in the control method of the image reading apparatus according to the fourth aspect, the predetermined signal processing is a shading correction processing.

According to a sixth aspect of the present invention, in the control method of the image reading apparatus according to the fifth aspect, the correcting step corrects a shading correction coefficient used in the shading correction processing. And

In order to achieve the above object, the storage medium according to the present invention comprises an automatic document feeder for automatically feeding the original to a position where an image described on the original is read,
A storage medium storing a program that can be implemented by a computer, including a control method for controlling an image reading device that reads an image of a document being conveyed by the automatic document conveyance means, wherein the control method is performed by the automatic document conveyance means. A light irradiating step of irradiating the original being conveyed with light by a light irradiating unit, and an electric conversion unit that receives light reflected from the original according to the irradiated light and converts the received light into an electric signal. Correcting a predetermined signal processing of the signal processing according to a processing step of performing signal processing on a signal and a distance measured by a measuring unit that measures a distance between the original being conveyed and the light irradiation unit; And a correction step of performing the correction.

The storage medium according to claim 8 is the storage medium according to claim 7, wherein the predetermined signal processing is shading correction processing.

According to a ninth aspect of the present invention, in the storage medium of the sixth aspect, in the correcting step, a shading correction coefficient used in the shading correction processing is corrected.

[0033]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In the present embodiment, a copying machine is shown as an application example of the present invention. However, the present invention is not limited to this, and it goes without saying that the present invention can be applied to various other apparatuses.

FIG. 1 is a sectional view showing a schematic configuration of an image reading apparatus according to an embodiment of the present invention, and as described above, the present invention is applied to a color copying machine.

Referring to FIG. 1, the image reading apparatus according to the present embodiment is mainly constituted by an automatic document feeder 200, an image scanner unit 201, and a printer unit 202.

The automatic document feeder 200 feeds a document to the image scanner unit 201.

The image scanner unit 201 reads a document and performs digital signal processing.

The printer unit 202 prints out an image corresponding to the original image read by the image scanner unit 201 on recording paper in full color.

In the image scanner section 201, a document 204 on a platen glass (hereinafter, referred to as "platen") 203 is irradiated with light from a xenon tube lamp 205, and reflected light from the document is guided to reflection mirrors 206 and 207. Then, an image is formed on the three-line sensor 210 by the lens 209. The three-line sensor 210 extracts electric signals corresponding to the red (R) component, the green (G) component, and the blue (B) component, which are full-color information, from the reflected light, and transmits the signals to the signal processing unit 211.

The signal processing unit 211 performs predetermined signal processing on each of the transmitted electric signals, and outputs the processed signals to the printer unit 202. The printer unit 202 forms a copy image of the document based on this signal.

The first mirror unit 208 having the xenon tube lamp 205 and the reflecting mirror 206 has a speed of v, and the second mirror unit 2071 having the reflecting mirror 207 has a speed of v / 2. The original is scanned by a motor (not shown) in a direction (hereinafter, referred to as a “sub-scanning direction”) perpendicular to a target scanning direction (hereinafter, referred to as a “main scanning direction”).

The standard white plate 5102 is used for correcting data read from the three-line sensor 210 when the xenon lamp 205 is used.

When an original is read by the automatic document feeder 200 using the automatic document feeder 200, the first mirror unit 208 is held below the original reading glass 14, and the original is read. , Continuous reading of a document can be realized in a short time.

FIG. 2 is a sectional view showing the structure of an automatic document feeder 200 used in the present invention.
The same reference numerals are given to those having the same functions as those described above, and the description thereof will be omitted.

In FIG. 2, a displacement detection sensor 16 is provided in the vicinity of the large conveying roller 1, and the displacement detection sensor 1 is provided.
Numeral 6 detects the amount of vertical displacement of the large conveying roller 1.

Returning to FIG. 1, the signal processing unit 211 converts the image signal read by the three-line sensor 210 into a digital signal, performs predetermined processing, and temporarily stores the converted signal in a memory (not shown). When the original is a color image, an image signal decomposed into magenta (M), cyan (C), yellow (Y), and black (BK) components in synchronization with the image forming process of the printer unit 202 is output to the printer unit. 202. If the original is a black and white image,
The image signal stored in the memory in the signal processing unit 211 is digitally processed, and an image signal of a black (BK) component is transmitted to the printer unit 202 in synchronization with an image forming process of the printer unit 202.

The M, C, Y, and BK image signals transmitted from the image scanner unit 201 are transmitted to the laser driver 212. The laser driver 212 modulates and drives the semiconductor laser 213 according to the transmitted image signal. The laser beam passes through the polygon mirror 214, the f-θ lens 215 and the mirror 216,
7 is scanned.

The rotary developing device 218 includes the magenta developing device 21
9, four developing units 219 to 222 are alternately in contact with the photosensitive drum 217, and are formed on the photosensitive drum 217. M, C, Y, and M are formed by a cyan developing unit 220, a yellow developing unit 221 and a black developing unit 222. Each electrostatic latent image of BK is developed with the corresponding toner.

The transfer drum 223 includes a paper cassette 224
Alternatively, the paper fed from 225 is wound, and the toner image developed on the photosensitive drum 217 is transferred to the paper.

After the four colors of M, C, Y, and BK are sequentially transferred in this manner, the sheet passes through the fixing unit 226 and is discharged.

FIG. 3 is a diagram showing an example of the configuration of the three-line sensor 210.

Referring to FIG.
10-2 and 210-3 are for reading each wavelength component of R, G and B, respectively.

The three light receiving element rows having different optical characteristics are monolithically mounted on the same silicon chip so that the R, G, and B sensors are arranged parallel to each other to read the same line of the document. It is configured.

FIG. 4 is an enlarged view in which the light receiving element array of FIG. 3 is enlarged.

As shown in FIG.
Reference numeral 210-3 denotes one pixel in the main scanning direction, for example, one pixel.
It has a width of 0 μm. Then, each sensor 210-1
210-3, so that the short side direction (297 mm) of the A3 document can be read at a resolution of 400 dpi.
There are 5000 pixels in the main scanning direction. The distance between the lines of the R, G, and B sensors 210-1 to 210-3 is, for example, 80 μm, and each line is separated by 8 lines for a sub-scanning resolution of 400 lpi. Further, in each of the line sensors 210-1 to 210-3, an optical filter is formed on the sensor surface in order to obtain predetermined spectral characteristics of R, G, and B.

FIG. 5 is a block diagram showing the configuration of the image scanner unit 201.

In the figure, an image signal output from the CCD 210 is input to an analog signal processing unit 4001, converted into an 8-bit digital image signal in the analog signal processing unit 4001, and then converted to a shading correction unit 4.
002.

FIG. 6 is a block diagram showing the configuration of the analog signal processing section 4001. Here, since the processing circuits for R, G, and B are all the same, only the circuit for one color is shown.

In the figure, an image signal output from the CCD 210 is sent to a sample & hold (S / H) section 410.
Sample & 1 to stabilize the analog signal waveform
It is held. A CPU (not shown) converts the image signal into an A / D converter 41 via a voltage control circuit 4103.
To make full use of the dynamic range of 05,
The variable amplifier 4103 and the clamp circuit 4102 are controlled. The A / D converter 4105 converts the analog image signal into
For example, it is converted into an 8-bit digital image signal.

Referring back to FIG. 5, the 8-bit digital image signal is subjected to shading correction by a known shading correction method in a shading correction unit 4002. When reading shading data, the CPU responds to a read signal from the three-line sensor 210.
Stores a read signal for one line from the standard white plate 5102 in the line memory 4003, and sets a shading correction coefficient for setting the read data of each pixel stored in the line memory 4003 to a predetermined level, for example, 240, in the pixel. Calculated for each line, and this is stored in the coefficient memory
005. When reading the original,
In synchronization with the output of each pixel by the line reading of the line sensor 210, the shading correction coefficient corresponding to the pixel is read from the coefficient memory 4005,
At 07, shading correction is performed by multiplying each pixel signal from the three-line sensor 210.

At the time of scanning original reading, the displacement detection sensor 16 detects the vertical displacement of the transport roller large 1 and calculates the distance X between the xenon tube lamp 205 and the transport roller large 1 from the detected displacement. The shading correction coefficient is corrected in real time according to the calculated distance X. Here, the transport roller large 1 is used to scan the original document glass 1
Y = a (X / X ₀ ) ² + b where a and b are constants, and the shading correction coefficient is multiplied by the calculated value Y from the distance X ₀ when the lens is in contact with the distance 4 and the distance X during operation. are doing.

Next, the correction of the physical distance of the three-line sensor 210 will be described.

As shown in FIG. 4, since the light receiving sections 210-1, 210-2 and 210-3 of the sensor 210 are arranged at a fixed distance, the delay elements 401 and 402 cause the light receiving sections 210-1, 210-2 and 210-3 to move in the sub-scanning direction. Is corrected. More specifically, the R and G signals read earlier in the sub-scanning direction with respect to the B signal are delayed in the sub-scanning direction and superimposed on the B signal.

The first look-up table (hereinafter referred to as "L
Reference numeral 4008) is used to correct the gradation of the original image reading signal. A document on which an image having a predetermined density shown in FIG. 7 is drawn is placed on the platen 203, and document image data is read. As shown in FIG. 8, when the read level 1001 does not have linearity, linearity is obtained. The input signal is corrected by the correction curve 1002 to
03.

The memory 4009 temporarily stores the image signal, and outputs the image signal in synchronization with the printer unit 202. In addition, from the memory 4009, a predetermined density (hereinafter, referred to as a predetermined density)
The data is output as “PG”, and the printer unit 203 generates a PG image similar to the image shown in FIG.

The log converters 403 to 405 are constituted by a look-up table ROM, and convert a luminance signal into a density signal.

The second LUT 4010 is the first LUT 4
The circuit similar to 008 performs gradation correction of the printer unit 203.

A PG image based on the PG data output from the memory 4009 is read by the image scanner unit 201, and the read data and the memory 40 are read.
The PG data output from step 09 is compared, and if linearity is not obtained in the PG image, the input signal is corrected with a correction curve and output as shown in FIG.

The masking and UCR circuit 406 is a well-known circuit, and the detailed description is omitted. However, the Y, M, C, and BK signals for output are read each time the reading operation is performed by the input three primary color signals. Are sequentially output at a predetermined bit length, for example, 8 bits.

The above circuits are controlled by a CPU (not shown).

The operation processing executed by the image reading apparatus configured as described above will be described below with reference to the flowchart of FIG.

In FIG. 9, first, when an operator sets a document on the document feed tray 9 of the automatic document feeder 200 (step S1) and starts a copy operation from an operation unit (not shown) (step S2), the operation is not shown. CPU
Moves the first mirror unit 208 under the reference white plate 5102, reads one line of shading correction data, and stores the calculated shading correction coefficient in the coefficient memory 400 in the shading correction circuit 4002.
6 is set (step S3).

Next, the first mirror unit 208 is moved to a position below the original reading glass 14 (step S).
4).

Next, the feed roller 8 of the automatic document feeder 200 is lowered onto the document 204 (FIG. 11A),
04 is picked up, and the document 204 is conveyed to the lower registration roller 3 and the upper registration roller 4 by rotation of the conveyance roller 6. At the lower registration roller 3 and the upper registration roller 4, a loop is formed in the sheet, and the skew of the sheet is corrected (FIG. 11B).

Next, the document 204 is pressed against the large conveying roller 1 by the roller 2 and is conveyed in accordance with the rotation of the large conveying roller 1 to prevent the document 204 from being separated from the large conveying roller 1 by the small lead roller 13. (FIG. 11
(C)).

Next, the original 204 is conveyed onto the original reading glass 14 to perform an original image reading operation. The original 204 is ejected while preventing the original 204 from being separated from the conveying roller 1 by the large lead roller 12. The sheet is conveyed to the upper paper roller 11 and the lower paper discharge roller 10 (FIG. 11D).

Next, the original 204 is discharged to the discharge tray 15 by the upper discharge roller 11 and the lower discharge roller 10 (FIG. 11E). At this time, the CPU detects the amount of vertical displacement of the transport roller large 1 by the displacement detection sensor 16, calculates the distance X between the xenon tube lamp 205 and the transport roller large 1 from the detected displacement, and calculates the calculated distance. The shading correction coefficient is corrected in real time according to X. Specifically, from the distance X ₀ when the conveying roller large 1 is in contact with the original glass 14 and the operating distance X, Y = a (X / X ₀ ) ² + b where a and b are constants. Is calculated, the shading correction coefficient is multiplied by the calculated value Y, and the real-time shading correction coefficient is corrected line by line (step S
5) The original image data is read into the memory 4009 (step S6).

Next, the document flow reading operation (steps S5 and S6) is repeated (step S7) until there is no document placed on the automatic document feeder 200 (step S7). Is read out, a copy image is formed by the printer unit 202 (step S8), and the copy operation ends.

In the present embodiment, a method of printing all original image data after storing it in memory 4009 has been described. However, a method of printing and outputting original image data while reading it into memory 4009 is adopted. Is also good.

A storage medium storing a program code of software for realizing the functions of the above-described embodiment is supplied to a system or an apparatus, and a computer (or CPU or MPU) of the system or the apparatus stores the storage medium in the storage medium. It goes without saying that the object of the present invention is also achieved by reading and executing the program code.

In this case, the program code itself read from the storage medium realizes the novel function of the present invention, and the storage medium storing the program code constitutes the present invention.

Examples of the storage medium for supplying the program code include a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, and C
A D-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used. Further, the program code may be supplied from a server computer via a communication network.

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

Further, after the program code read from the 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, based on the instruction of the program code, It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

[0086]

As described above, according to the first, fourth or seventh aspect of the present invention, the original being conveyed by the automatic original conveying means is irradiated with light by the light irradiating means, and the light is irradiated. The electric signal converted by the photoelectric conversion means for receiving the light reflected from the original according to the light and converting the light into an electric signal is subjected to signal processing. Since the correction is made in accordance with the distance measured by the measuring unit that measures the distance between the original document and the light irradiation unit, even when reading the original image while sending the original document to the image reading device by the automatic document conveyance unit, The original image can be read accurately. More specifically, it is possible to realize image reading without deterioration of a document image reading signal due to vertical movement of the transport roller.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image reading apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of the automatic document feeder of FIG.

FIG. 3 is a diagram showing a configuration of a CCD sensor used in the image reading device of the present embodiment.

FIG. 4 is an enlarged view of a light receiving element of the CCD sensor of FIG.

FIG. 5 is a block diagram illustrating a configuration of a signal processing unit used in the image reading device according to the present embodiment.

FIG. 6 is a block diagram illustrating a configuration of an analog signal processing unit used in the image reading device according to the present embodiment.

FIG. 7 is a diagram illustrating an example of a PG image.

FIG. 8 is a diagram for explaining one method of gradation correction.

FIG. 9 is a flowchart illustrating a procedure of an operation process performed by the image reading apparatus of FIG. 1;

FIG. 10 is a cross-sectional view illustrating a configuration of a conventional automatic document feeder.

FIG. 11 is a diagram for explaining how a document is sent by the automatic document feeder of FIG. 10;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Large conveyance roller 2 Roller 3 Below the registration roller 4 Above the registration roller 6 Transportation roller 8 Feed roller 9 Document feed tray 10 Below the discharge roller 11 Above the discharge roller 12 Large lead roller 13 Small lead roller 14 Flowing document reading glass 16 Displacement Detection sensor 200 Automatic document feeder 201 Image scanner unit 202 Printer unit 203 Document table glass 205 Xenon tube lamp 206, 207 Reflection mirror 2071 Second mirror unit 208 First mirror unit 209 Lens 210 3-line sensor 211 Signal processing unit 212 Laser driver 213 Semiconductor laser 214 Polygon mirror 215 f-θ lens 216 Mirror 217 Photosensitive drum 218 Rotary developing device 223 Transfer drum 224, 225 Paper cassette 226 Fixing unit 51 02 Standard white plate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H108 AA12 FA01 5B047 AA01 AB04 BA01 BB02 BC05 BC09 BC11 BC14 CB09 DA04 DC06 5C072 AA01 BA17 CA03 DA02 DA04 DA12 EA05 FA08 FB12 RA16 RA18 UA02 UA12 UA17 XA01 5C037 PP04 PP48 PQ12 PQ23 SS01

Claims (9)

[Claims] An automatic document feeder configured to automatically feed a document to a position where an image written on the document is read;
In an image reading apparatus for reading an image of a document being conveyed by the automatic document conveyance means, light irradiating means for irradiating light to the document being conveyed by the automatic document conveyance means, and Photoelectric conversion means for receiving the reflected light and converting it into an electric signal; processing means for performing signal processing on the converted electric signal; and measuring a distance between the original being conveyed and the light irradiation means. An image reading apparatus, comprising: a measuring unit that performs predetermined signal processing in the signal processing in accordance with the measured distance. 2. The image reading apparatus according to claim 1, wherein the predetermined signal processing is a shading correction processing. 3. The image reading apparatus according to claim 2, wherein the correction unit corrects a shading correction coefficient used in the shading correction processing. 4. An automatic document feeder for automatically feeding a document to a position where an image written on the document is read,
In a control method for controlling an image reading device that reads an image of a document being conveyed by the automatic document conveyance means, a light irradiation step of irradiating light by light irradiation means to the document being conveyed by the automatic document conveyance means, A processing step of receiving light reflected from the original in accordance with the irradiated light and performing signal processing on the electric signal converted by the photoelectric conversion means for converting the light into an electric signal; and A correction step of correcting a predetermined signal processing of the signal processing according to a distance measured by a measuring means for measuring a distance from the irradiating means. 5. The method according to claim 4, wherein the predetermined signal processing is shading correction processing. 6. The method according to claim 5, wherein in the correction step, a shading correction coefficient used in the shading correction processing is corrected. 7. An automatic document feeder for automatically feeding a document to a position where an image written on the document is read,
A storage medium storing a program that can be implemented by a computer, including a control method for controlling an image reading device that reads an image of a document being conveyed by the automatic document conveyance device, wherein the control method is performed by the automatic document conveyance device. A light irradiating step of irradiating the original being conveyed with light by light irradiating means; A signal processing step of performing signal processing on a signal; and correcting a predetermined signal processing of the signal processing according to a distance measured by a measuring unit that measures a distance between the original being conveyed and the light irradiation unit. And a correcting step of performing the following. 8. The storage medium according to claim 7, wherein said predetermined signal processing is shading correction processing. 9. The storage medium according to claim 8, wherein in the correction step, a shading correction coefficient used in the shading correction processing is corrected.