JP2002281255A - Image reading apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a long-life system by detecting abnormality of a lamp before shading operation and avoiding useless shading operation. SOLUTION: The image reading apparatus includes a manuscript sheet feeder for carrying the manuscript to be exposed at a constant speed, slit glass 1006 for reading the exposed manuscript, a shading plate 104, a scanner carriage 1005 having a reading function and capable of being driven, and a small white plate with the same color as the reference white at a position having no influence on the manuscript reading on the slit glass face. In addition, a control means is provided. During the reading operation, an exposing lamp 1001 is lightened and a white peak value of the small white plate is detected through the control means without moving the scanner carriage 1005. The control means determines that it is an abnormal condition or the shading operation should be carried out on the basis of whether an absolute differential value between the detected value and the detected normal value is larger or smaller than a prescribed value.

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, and more particularly, to an image reading apparatus used in a digital copying machine, a digital multifunction peripheral, and the like.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. Hei 10-182221 discloses an image reading apparatus provided with an automatic document feeder (ADF) for automatically feeding and reading a plurality of originals in order to copy the originals in a short time. A basic configuration is disclosed.

Japanese Patent Laid-Open No. Hei 10-271279 discloses an image reading apparatus having an automatic document feeder (ADF). In a sheet-through type image reading apparatus, a white plate reading operation (shading) is performed before reading an original. It is disclosed that this also performs a lamp check.

[0004]

However, as described in the above-mentioned prior art, moving the carriage to a white plate for shading operation causes a time loss. Even if an attempt is made to reduce the number of times of shading, if shading data is used for a lamp check, it is necessary to perform a shading operation for a lamp check every time a document is read.

As described above, since the shading data can also be used for the lamp check, it is preferable to perform the shading operation every time one document is read. However, when the lamp check is performed by the shading operation, the shading operation is performed every time. Even if it is not necessary, it must be performed for the lamp check, and the throughput cannot be increased. In particular, when the reading position of the original is different from the position of the shading plate, this problem becomes conspicuous.

Conversely, if the shading operation is not performed every time a document is read in order to increase the throughput, a lamp abnormality cannot be detected, and an abnormal image may result. On the other hand, if a mechanical means is used as a means for detecting a lamp abnormality when the shading operation is not performed every time a document is read, if the detection operation is performed every time by the mechanical means, the life of the mechanical means cannot be extended. Problems arise.

Therefore, attention is paid to a slit glass portion corresponding to a reading portion characteristic of a sheet-through type document feeder (DF), and a white plate (shading plate) is provided at both ends (outside the effective reading range) of the slit glass portion. It is conceivable to perform a lamp check by mounting a white plate of the same color and reading the white peak value of the white plate at the reading position. That is, by performing a lamp check before the reading operation, a lamp abnormality is detected before the reading operation. Therefore, even when the shading operation is not performed every reading, the lamp abnormality can be detected and an abnormal image can be prevented. Can be.

However, in such a process of comparing the white peak value of a white platelet with a predetermined value, there is a problem that an appropriate judgment cannot be made due to individual differences of a system including a white platelet or the like.

In view of the above problems, a first object of the present invention is to compare a normal value of a white peak already read on a white platelet with a value read this time before performing a shading operation. It is an object of the present invention to provide an image reading apparatus capable of prolonging the life of an apparatus by properly detecting a lamp abnormality so that the apparatus does not perform useless shading operation.

A second object of the present invention is to re-detect a lamp abnormality in consideration of a case where there is a variation in lamp abnormality detection due to a bad start of lamp lighting or the like in addition to the first object. Accordingly, an object of the present invention is to provide an image reading apparatus capable of accurately detecting a lamp abnormality.

A third object of the present invention, in addition to the second object, is to perform lamp abnormality detection a predetermined number of times in consideration of a case where lamp abnormality detection varies due to a bad start of lamp lighting or the like. Accordingly, it is an object of the present invention to provide an image reading apparatus capable of detecting a lamp abnormality more accurately.

A fourth object of the present invention is to compare the normal value of the white peak already read on the white platen with the value read this time before the reading operation to properly detect the lamp abnormality. Accordingly, it is an object of the present invention to provide an image reading apparatus capable of preventing an abnormal image from being read due to a lamp abnormality and improving throughput.

A fifth object of the present invention is to provide a method for detecting a lamp abnormality again in consideration of a case where there is a variation in lamp abnormality detection due to, for example, poor starting of lamp lighting, in addition to the fourth object. Accordingly, an object of the present invention is to provide an image reading apparatus capable of accurately detecting a lamp abnormality.

A sixth object of the present invention, in addition to the fifth object, is to perform lamp abnormality detection a predetermined number of times in consideration of a case where lamp abnormality detection varies due to poor starting of lamp lighting or the like. Accordingly, it is an object of the present invention to provide an image reading apparatus capable of detecting a lamp abnormality more accurately.

[0015]

The present invention employs the following means in order to solve the above-mentioned problems.

The first means includes a document feeder for conveying the document to be exposed at a constant speed, a slit glass provided for reading the document to be exposed, a shading plate, and a reading function. In an image reading apparatus provided with a drivable scanner carriage and a white platen of the same color as the reference white plate at a position on the slit glass surface that does not affect reading of the original, the scanner is configured to perform the scanning Without moving the carriage, the exposure lamp is turned on to detect the white peak value of the white plate, and whether the absolute value of the difference between the detected value and the normal value already detected is smaller or larger than a certain value. By
A control means for determining whether to perform a shading operation or to set an abnormal state is provided.

The second means is the first means, wherein the control means turns on the exposure lamp again and detects the white peak value of the white plate when the control means determines that the state is abnormal. It is characterized in that whether to perform a shading operation or to set an abnormal state is determined depending on whether the absolute value of the difference between the detected value and the already detected normal value is smaller or larger than a certain value.

The third means is the first means, wherein the control means turns on an exposure lamp to detect a white peak value of the white platelet when the control means determines that the state is abnormal. Depending on whether the absolute value of the difference between the detected value and the already detected normal value is smaller or larger than a certain value,
It is characterized in that a process of performing a shading operation or setting an abnormal state is repeated a predetermined number of times.

The fourth means includes a document feeder for conveying a document to be exposed on a platen at a constant speed, a slit glass provided for reading the exposed document,
A scanner carriage provided with a reading function and operably provided, and an image reading apparatus provided with a white platen of the same color as the reference white plate at a position on the slit glass surface which does not affect reading of the document. During operation, without moving the scanner carriage, the exposure lamp is turned on to detect the white peak value of the white plate, and the absolute value of the difference between the detected value and the previously detected normal value is a constant value. Control means is provided for determining whether the reading operation is to be performed or to be in an abnormal state depending on whether the reading operation is smaller or larger.

A fifth means is the fourth means, wherein the control means turns on the exposure lamp again and detects the white peak value of the white plate when the control means determines that the state is abnormal. It is characterized in that it is determined whether the reading operation is to be performed or to be in an abnormal state, respectively, depending on whether the absolute value of the difference between the detected value and the already detected normal value is smaller or larger than a certain value.

The sixth means is the fourth means, wherein the control means, when determining in the determination that the state is abnormal, turns on the exposure lamp again and detects the white peak value of the white platelet. It is characterized by repeatedly determining a predetermined number of times whether to perform the reading operation or an abnormal state, respectively, depending on whether the absolute value of the difference between the detected value and the already detected normal value is smaller or larger than a certain value. I do.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a diagram showing an outline of the configuration inside a digital copying machine to which the image reading apparatus of the present invention is applied.

As shown in FIG. 1, the image reading apparatus comprises a scanner driving motor 1000, an exposure lamp 1001, a mirror 1002, a CCD 1003, and the like on a digital copying machine. A scanner carriage 1005, which will be described later, includes an exposure lamp 1001 and a mirror 1002 for allowing light to enter a CCD 1003.
000. A detailed description of the digital copying machine will be omitted.

FIG. 2 is a diagram showing an outline of a hardware configuration of the digital copying machine shown in FIG. 1, and a detailed description thereof will be omitted.

FIG. 3 is a diagram showing an outline of a software configuration of the digital copying machine shown in FIG. 1. As shown in FIG. 3, in the case of a digital copying machine, a multitasking type system configuration is used to copy. Various applications other than the application 900 can be installed. The copy application 900 performs control related to image formation, and in order to configure a multitasking system, manages a function unit as a resource and shares one resource among a plurality of applications. This management is performed by the system control layer 80.
In the system control layer 801, the system controller 902 undertakes all input and output of information of each controller and each application. The device control layer 802 includes:
From logical instructions such as commands and control signals from the system control layer 801, conversion for driving and inputting mechanical inputs and outputs such as clutches, sensors, and motors to actually move the apparatus is performed.

FIG. 4 shows an automatic document feeder (sheet-through double-sided ADF) arranged above the digital copying machine and a scanner carriage 1005 arranged below the apparatus.
FIG.

This automatic document feeder adopts a document moving type exposure system in which an exposure optical system is fixed at a fixed exposure position formed in a slit shape and an exposure operation is performed while conveying a document at a constant moving speed. The document feed tray 120 and the document discharge tray 123 are arranged above and below the platen 124 in two stages, and the reversing tray 121 is connected to the document feed tray 120 and the discharge tray to provide a reversing path for reversing the document. It is provided between 123. The document feed tray is provided with a document set sensor 193 for detecting the setting of a document, a bottom plate solenoid 192 for moving the document to a paper feed port, and a paper feed clutch 134 for driving a paper feed belt. The document set sensor 193 is a transmission type sensor, and detects a document with the filler pushed up by the document. The reversing switch 130 has a function of selecting whether the document conveyed from the reading position 132 is conveyed to the reversing tray 121 or discharged to the discharge tray 123. Inversion switching is operated by a solenoid. Three sensors are provided to control the conveyance of the paper.
01, a paper ejection sensor 102, and a reversing tray sensor 103. The three sensors are reflection sensors with filters. Each roller is driven by two stepping motors, and the paper feeding belt 110, the separation roller 111 and the reversing roller 115 are driven by a reversing paper feeding motor (normal rotation,
Reversible), pull-out roller 112, auxiliary roller 11
3 and the paper discharge roller 114 are driven by a transport motor (only in one direction). The reversing roller 115 is provided with a torque limiter to cope with the case where the paper moves in the rotation direction.

FIG. 5 is a flowchart showing the processing procedure of sheet through shading.

The reference white plate 1004 is, as shown in FIG.
Since the document reading position 132 (position A) is different from the shading position (position B), it is necessary to move the scanner carriage 1005 during the shading operation. While the scanner carriage 1005 moves from position A to position B (step 100-1), the reference white plate 1004
Is read to generate shading data (step 100-2). Then, the scanner carriage 1005
Is stopped at the position B (Step 100-3), moved from the position B to the position A, and stopped (Step 100-5, Step 100-6).

FIG. 6 is a diagram for explaining the flow of image data relating to shading correction.
Image data 200-1 read by D1003
Is amplified by the A / D converter 200-2 and input to the shading correction circuit 200-3.
The input image data is obtained by the shading operation described above, corrected by shading data stored in the shading data memory 200-5, and then corrected by the image processing unit 200-4 and the image forming unit 2.
The processing is sequentially performed at 00-8. In addition, in the copying machine,
As shown in the figure, a timer is provided as the peripheral device 200-9, and the counter is periodically counted up, and time is measured based thereon, thereby controlling the lighting time of various lamps and the like. I have. Here, after the reading, if there is no next operation instruction for a certain period of time, the lamp is controlled to be turned off.

FIG. 7 is a diagram showing an outline of the configuration of an image reading apparatus of a digital copying machine. FIG. 7A is a plan view seen from the slit glass reading unit 1006 side, and FIG.
Is a side view thereof.

As shown in the figure, in the present invention, a small white plate 1007 of the same color as the reference white plate 1004 is attached to both ends or one end of the slit glass reading unit 1006 so that the white surface faces the scanner carriage 1005. It is characterized by being. The position of the white platen 1007 does not affect the reading of the document, but is attached to a position where the image can be read. The DF member 1008 located on the upper surface of the slit glass is at least darker than the white small plate.

With this configuration, when the lamp is checked, the lamp 10 is stopped at the home position (position A) while the scanner carriage 1005 is stopped.
01 is turned on, the image data at that position is taken in,
The white peak data value of the white plate 1007 is obtained. As the white peak data value, the highest value (white value) among the captured white data values is extracted. Although there are various methods for this purpose, in the present embodiment, in FIG. 6, after the input and read image data 200-1 is converted by the A / D converter 200-2, the white platelet peak detection circuit 200- The peak value is detected at 12, and it is determined whether the lamp is abnormal by determining whether the absolute value of the difference between the already detected white peak value and the normal value of the white peak value is larger or smaller than a predetermined value. Determine whether or not. In the following, this series of controls will be referred to as white plate check.

FIG. 8 is a diagram showing a timing chart of reading the white plate 1007. The data capture period 300-2 of the white plate 1007 is, as shown in FIG.
Data acquisition can be performed at any timing as long as the timing is other than the shading data acquisition period 300-3 and the image reading period 300-4.

FIG. 9 is a flowchart showing a processing procedure of the white plate check according to the present embodiment. First, operation parameters necessary for the reading operation are set (step 400-1), and then the lamp is turned on (step 400-1). Step 40
0-2), without moving the scanner carriage 1005,
A white plate check is performed (step 400-3). Next, it is determined whether or not the absolute value of the difference between the current white peak value at the time of the white plate check and the normal value at the previous white plate check is greater than a predetermined value (step 400-4). If the value is larger than the value, the operation is interrupted or terminated assuming that the lamp is in an abnormal state, and the fact that the lamp is abnormal is displayed on a screen (not shown) of the digital copying machine (step 400-6). If it is smaller, a shading operation is performed (step 400-5).

FIG. 10 is a flowchart showing a processing procedure of a white plate check which is different from the white plate check shown in FIG. 9 according to the present embodiment. As shown in FIG. (Step 500)
-1) and then turn on the lamp (step 500-
2), a small white plate check is performed without moving the scanner carriage 1005 (step 500-3). Next, it is determined whether or not the absolute value of the difference between the current white peak value at the time of the white plate check and the normal value at the previous white plate check is larger than a predetermined value (step 500-4). If it is larger than the value, Step 500-2 to Step 500
The same processing as in step -4 is repeated. That is, the lamp is turned on again (step 500-5), and the scanner carriage 100
Check the white platelet without moving 5 (Step 500-
6) It is sequentially determined whether or not the absolute value of the difference between the current white peak value at the time of the white plate check and the normal value at the time of the previous white plate check is greater than a predetermined value (step 500-7). Do. If the value is larger than the predetermined value even after the white plate check is performed again, the operation is interrupted or terminated assuming that the lamp is in an abnormal state, and the fact that the lamp is abnormal is displayed on the screen of the digital copying machine (step 500). -9). If it is determined in step 500-4 and step 500-7 that the value is smaller than the predetermined value, a shading operation is performed (step 500-8).

FIGS. 11A and 11B show an embodiment of the present invention.
It is a flowchart which shows the processing procedure of the white plate check which is different from the white plate check shown in FIG. 0. First, the operation parameter required for a reading operation is set, the repetition counter of the white plate check is cleared, and the white plate check is performed. The number of checks is set (step 600-1). Next, the lamp is turned on (step 600-3), and the first white plate check is performed without moving the scanner carriage 1005 (step 600-4). Next, it is determined whether or not the absolute value of the difference between the current white peak value at the time of the white plate check and the normal value at the previous white plate check is larger than a predetermined value (step 600-5). If it is determined that the value is smaller than the predetermined value, a shading operation is performed (step 600-9). If it is determined that it is larger than the predetermined value,
The white plate check number counter is counted up (step 600-6), and it is determined whether or not the counter value is smaller than a set white plate check number (step 60).
0-7), if smaller, the process from step 600-2 is repeated (step 600-10). That is, the lamp is turned on again (step 600-3), the white plate is checked (step 600-4), and the difference between the current white peak value when the white plate is checked and the normal value when the previous white plate is checked is checked. Judge whether the absolute value is larger than a predetermined value (Step 6
00-5) is performed sequentially.

Even if such processing is repeated, the determination (step 600-5) that the absolute value of the difference from the normal value at the time of the white plate check is larger than the predetermined value is repeated, and the counter value is set. If it is determined that the number of the white platelet checks is greater than the number of times (step 600-7), it is determined that the lamp is in an abnormal state, and the operation is interrupted or terminated.
A lamp abnormality is displayed on the screen of the digital copying machine (step 600-8).

Next, a second embodiment of the present invention will be described with reference to FIGS. 1 to 8 and FIGS.

Since FIGS. 1 to 8 have already been described, their description will be omitted.

In this embodiment, if the absolute value of the difference between the white peak value of the white platelet detected in the first embodiment and the already detected normal value is smaller than a predetermined value, the shading operation is performed. Is different from the first embodiment in that a reading operation is started.

The processing procedure of the white plate check according to this embodiment will be described below.

FIG. 12 is a flowchart showing a processing procedure of the white plate check according to the present embodiment.
The operation parameters required for the reading operation are set (step 700-1), and then the lamp is turned on (step 7).
00-2) A white plate check is performed without moving the scanner carriage 1005 (step 700-3). Next, it is determined whether or not the absolute value of the difference between the current white peak value at the time of the white plate check and the normal value at the previous white plate check is larger than a predetermined value (step 700-4).
If it is larger than the predetermined value, the lamp is determined to be in an abnormal state, the operation is interrupted or terminated, and the fact that the lamp is abnormal is displayed on a screen (not shown) of the digital copying machine (step 700-6), and the predetermined value is set. If smaller, a reading operation is performed (step 700-5).

FIG. 13 is a flowchart showing a processing procedure of a white plate check which is different from the white plate check shown in FIG. 12. As in FIG. 12, operation parameters required for the reading operation are set (step 800). -1) Then, the lamp is turned on (step 800-2), and a small white plate check is performed without moving the scanner carriage 1005 (step 800-3). Next, it is determined whether the absolute value of the difference between the current white peak value at the time of the white plate check and the normal value at the previous white plate check is greater than a predetermined value (step 800-4). If the value is larger than the value, the same processing as in steps 800-2 to 800-4 is repeated. That is, the lamp is turned on again (step 800).
-5), checking the white platelet without moving the scanner carriage 1005 (step 800-6), the absolute value of the difference between the current white peak value when checking the white platelet and the normal value when checking the white platelet last time. It is sequentially determined whether the value is larger than a predetermined value (step 800-7). If the value is larger than the predetermined value even after the white plate check is performed again, the operation is interrupted or terminated assuming that the lamp is in an abnormal state, and the fact that the lamp is abnormal is displayed on the screen of the digital copying machine (step 800). -9). If it is determined in step 800-4 and step 800-7 that the value is smaller than the predetermined value, a reading operation is performed (step 800-8).

FIG. 14 is a flowchart showing a processing procedure of a white plate check which is different from the white plate check shown in FIGS. 12 and 13. First, operation parameters necessary for the reading operation are set, and the white plate check is performed. The check repetition counter is cleared and the number of white plate check is set (step 900-1). Next, the lamp is turned on (step 900-3), and the first white plate check is performed without moving the scanner carriage 1005 (step 90).
0-4). Next, it is determined whether or not the absolute value of the difference between the current white peak value at the time of the white plate check and the normal value at the previous white plate check is greater than a predetermined value (step 900-5). If it is determined that the value is smaller than the predetermined value,
A reading operation is performed (step 900-9). If it is determined that the value is greater than the predetermined value, the white plate check number counter is counted up (step 900-6), and it is determined whether the counter value is smaller than a set white plate check number (step 900-6). 900-7), if it is smaller, the processing from step 900-2 is repeated (step 9).
00-10). That is, the lamp is turned on again (step 9)
00-3), white plate check (step 900-3),
It is sequentially determined whether the absolute value of the difference between the current white peak value at the time of the white plate check and the normal value at the time of the previous white plate check is greater than a predetermined value (step 900-4).

Even if such processing is repeated, the determination that the absolute value of the difference from the normal value at the time of the previous white plate check is larger than a predetermined value (step 900-5) is repeated, and there is a counter value. If it is determined that the number of white plate check is larger than the set number (step 900-7), it is determined that the lamp is in an abnormal state, the operation is interrupted or terminated, and the lamp is abnormal on the screen of the digital copying machine. Is displayed (step 900-8).

[0048]

According to the first aspect of the present invention, a lamp abnormality can be detected before the shading operation is performed, mechanical unnecessary shading operation can be prevented, and the life of the apparatus can be extended. By comparing the white peak value with the already obtained normal value, there is an effect that the individual difference as a system is absorbed and more appropriate control can be performed.

According to the second aspect of the present invention, in addition to the effects of the first aspect of the present invention, even if it is determined that there is an abnormality in consideration of variations in the lamp, such as in the case where the lamp rises poorly, it is detected again. Has the effect of being able to make an accurate determination of lamp abnormalities, and by comparing the white peak value with the previous normal value, it is possible to absorb individual differences as a system and control it more appropriately. There is.

According to the third aspect of the invention, in addition to the effect of the second aspect of the invention, by setting an appropriate number of times of detection, it is possible to set the operation of the lamp check in accordance with the state of the machine. By comparing the white peak value with the previous normal value, individual differences as a system can be absorbed and more appropriate control can be performed.

According to the fourth aspect of the present invention, it is possible to detect a lamp abnormality before performing a reading operation, and it is possible to avoid taking in an abnormal image due to a lamp abnormality. By comparison, there is an effect that individual differences as a system can be absorbed and more appropriately controlled.

According to the fifth aspect of the present invention, in addition to the fourth aspect of the present invention, even if it is determined that the lamp is abnormal in consideration of variations in the lamp such as when the lamp rises poorly, detection is attempted again. As a result, there is an effect that an accurate judgment of a lamp abnormality can be made. By comparing a white peak value with a previous normal value, an individual difference as a system can be absorbed and an effect can be more appropriately controlled. .

According to the sixth aspect of the present invention, in addition to the fifth aspect of the present invention, by setting an appropriate number of detections, it is possible to set the lamp check operation according to the state of the machine. By comparing the white peak value with the previous normal value, there is an effect that individual differences as a system can be absorbed and more appropriate control can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a configuration in a digital copying machine to which an image reading apparatus of the present invention is applied.

FIG. 2 is a diagram showing an outline of a hardware configuration of the digital copying machine shown in FIG.

FIG. 3 is a diagram showing an outline of a software configuration of the digital copying machine shown in FIG. 1;

FIG. 4 is a diagram showing a relationship between an automatic document feeder (sheet-through double-sided ADF) arranged at an upper part of the digital copying machine shown in FIG. 1 and a scanner carriage arranged at a lower part of the apparatus.

FIG. 5 is a flowchart illustrating a processing procedure of sheet through shading.

FIG. 6 is a diagram for explaining the flow of image data related to shading correction.

7 is a diagram showing an outline of a configuration of an image reading device of the digital copying machine shown in FIG. 1;

FIG. 8 is a diagram showing a timing chart of reading of white platelets.

FIG. 9 is a flowchart illustrating a processing procedure of a small white plate check according to the first embodiment.

FIG. 10 is a flowchart showing a processing procedure of a white plate check which is different from the white plate check shown in FIG. 9 according to the first embodiment.

FIG. 11 is a flowchart showing a processing procedure of a white plate check which is different from the white plate check shown in FIGS. 9 and 10 according to the first embodiment.

FIG. 12 is a flowchart showing a processing procedure of a small white plate check according to the second embodiment.

FIG. 13 is a flowchart illustrating a processing procedure of a white plate check that is different from the white plate check shown in FIG. 9 according to the second embodiment.

FIG. 14 is a flowchart showing a processing procedure of a small white plate check different from the small white plate check shown in FIGS. 9 and 10 according to the second embodiment.

[Explanation of symbols]

 1000 Scanner drive motor 1001 Exposure lamp 1002 Mirror 1003 CCD 1005 Scanner carriage 1004 Reference white plate (shading plate) 1006 Slit glass reading unit 1007 White plate 1008 DF member

Continued on the front page F-term (reference) 2H108 HA00 JA06 2H109 DA11 5B047 AA01 BA01 BA02 BB02 BC09 BC11 BC14 CB22 DA04 DC01 DC06 5C072 AA01 BA13 CA02 CA17 DA04 EA05 FB12 LA15 RA16 UA02 UA13 XA01 5C077 MM27 PP06 PP03 PP04

Claims (6)

[Claims] 1. A document feeder for transporting a document to be exposed at a constant speed, a slit glass provided for reading the exposed document, a shading plate, and a reading function provided and operably provided. An image reading apparatus provided with a scanner carriage provided and a white platen of the same color as the reference white plate at a position on the slit glass surface which does not affect reading of the original, wherein the scanner carriage is moved during a reading operation Without turning on the exposure lamp, the white peak value of the white platelet is detected, and shading is performed depending on whether the absolute value of the difference between the detected value and the normal value already detected is smaller or larger than a certain value. An image reading apparatus comprising: a control unit that determines whether an operation is performed or an abnormal state is set. 2. When the control means determines in the determination that the state is abnormal, the control means turns on the exposure lamp again to detect the white peak value of the white plate, and the detected value has already been detected. 2. The image reading apparatus according to claim 1, wherein it is determined whether the shading operation is to be performed or an abnormal state is to be performed depending on whether an absolute value of a difference from a normal value is smaller or larger than a predetermined value. 3. The control means, when determining in the determination that the state is abnormal, turns on an exposure lamp to detect a white peak value of the white platelet, and determines the detected value as a normal value which has already been detected. 2. The image according to claim 1, wherein a process of performing a shading operation or an abnormal state is determined a predetermined number of times depending on whether an absolute value of a difference from the value is smaller or larger than a predetermined value. Reader. 4. A document feeder for conveying a document to be exposed on a platen at a constant speed, a slit glass provided for reading the exposed document, and a driving function provided with a reading function. Moving the scanner carriage during a reading operation in an image reading apparatus provided with a scanner carriage and a white platen of the same color as the reference white plate at a position on the slit glass surface that does not affect reading of the document. Instead, the exposure lamp is turned on to detect the white peak value of the white plate, and the reading is performed depending on whether the absolute value of the difference between the detected value and the previously detected normal value is smaller or larger than a certain value. An image reading apparatus comprising: a control unit that determines whether an operation is performed or an abnormal state is set. 5. If the control means determines that the state is abnormal, the control means turns on the exposure lamp again to detect the white peak value of the white platelet, and the detected value has already been detected. 5. The image reading apparatus according to claim 4, wherein it is determined whether the reading operation is to be performed or an abnormal state is to be performed depending on whether an absolute value of a difference from a normal value is smaller or larger than a predetermined value. 6. The control means, when determining in the determination that the state is abnormal, turns on the exposure lamp again to detect a white peak value of the white platelet, and the detected value has already been detected. 5. The image reading apparatus according to claim 4, wherein whether to perform the reading operation or set to the abnormal state is repeatedly determined a predetermined number of times depending on whether an absolute value of a difference from a normal value is smaller or larger than a predetermined value. .