JPH09247371A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain image data of high precision even if a component or transmission body deteriorate in precision with time. SOLUTION: A read start reference point 37 and a read end reference point 38 are arranged on the reverse surface of a 2nd document abutting member 36 and when the image reader is powered on, a prescan is made to extract an image of the read start reference point 37 and an image of the read end reference point 38; and the distance (number of lines) between those read start reference point 37 and read end reference point 38 is measured and on the basis of the measurement result, the number of read lines when an image of a document 5 is read out is adjusted.

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 used in an image scanner apparatus, a digital copying machine, a digital facsimile apparatus or the like for digitally reading image information on an original, and more particularly to a scanning length. The present invention relates to an image reading apparatus that compensates for this even by fluctuations by image processing and prevents deterioration of the quality of an image obtained by an image reading operation.

[0002]

2. Description of the Related Art In an image reading apparatus used in an image scanner apparatus, a digital copying machine, a digital facsimile apparatus or the like, while illuminating an original with light obtained by a light source, a reflected light or a reflected light is reflected by a photoelectric conversion element such as a CCD. After converting the transmitted light to an analog signal, A /
The analog signal is converted into a digital signal by the D converter, various kinds of image processing are applied to the image data (digital signal) obtained thereby, and the image data is output to the outside.

[0003]

By the way, in such an image reading apparatus, the image data obtained by the image reading operation may be different from the image of the actual document, and this is output as it is. Since this is not possible, various methods are used to correct this. For example, in such an image reading apparatus, since the scanning length in the main scanning direction is usually determined by the optical path length, the optical path length should be held at a preset length by optical adjustment. However, with respect to the scanning length in the sub-scanning direction, the traveling body is driven from the motor serving as a power source via a plurality of drive pulleys, drive wires, and other transmission bodies, so errors in component accuracy accumulate,
The scan length often deviates from the scan length at the design stage.
Therefore, the standard original is read at the time of factory shipment to adjust the feed amount of the drive motor so that the scanning length in the sub-scanning direction matches the scanning length at the design stage. As a result, the transmission body deteriorates, and the scanning length gradually deviates from an appropriate value. So, as a method to solve such problems,
"Copier" shown in Japanese Patent Laid-Open No. 01-082064,
An "image reading device" shown in Japanese Patent Laid-Open No. 05-022527 has been proposed. However, in the technique disclosed in each of these proposals, the dimensional accuracy is measured based on the image data obtained by reading the reference original,
Since the motor speed is controlled based on the measurement result to correct the dimensional accuracy in the sub-scanning direction, there is a problem that the scanning length error cannot be corrected unless a reference document is prepared.

The present invention has been made in view of the above circumstances. In claim 1, by disposing reference points at the reading start position and the reading end position, parts accuracy and transmission due to secular change or the like. An object of the present invention is to provide an image reading device that can obtain image data with high accuracy even if the accuracy of the body is lowered. In claim 2, the reading start position,
By arranging each reference point indicating the reading end position on one member, it is possible to obtain a high-accuracy reference interval by preventing stacking errors of parts and the like. An object of the present invention is to provide an image reading device that can obtain image data with high accuracy even if the accuracy and the accuracy of the transmission body decrease. According to the third aspect, by disposing the reference points outside the original area,
An image reading apparatus capable of obtaining high-precision image data even if the component accuracy or the accuracy of the transmission body is deteriorated due to secular change or the like because the calculation error when correcting the image data can be reduced. It is intended to be provided. According to a fourth aspect of the present invention, in both main scanning and sub scanning, the distance between the origin of the original area and the reference point is defined to be a constant value, so that the reading start position when reading the image of the original is accurately positioned. It is therefore an object of the present invention to provide an image reading apparatus that can obtain image data with high accuracy even if the accuracy of parts or the accuracy of the transmission body is deteriorated due to aging or the like.

[0005]

In order to achieve the above object, the present invention according to claim 1 radiates light from a light source to illuminate a document to be read while reflecting or transmitting the reflected light. In an image reading device that photoelectrically converts by a photoelectric conversion element and extracts image information on the document as an electric signal, a reading start reference point serving as a reference of a reading start position, and a reading end reference point serving as a reference of a reading end position. Scanning is performed by comparing the dimension between the reading start reference point and the reading end reference point with the dimension between the reading start reference point and the reading end reference point actually obtained by scanning with the photoelectric conversion element. A scan length difference calculation unit for calculating a length difference, and a correction unit for correcting a scan length error of an image obtained by the photoelectric conversion element based on the scan length difference obtained by the scan length difference calculation unit are provided. Is characterized by. According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, the reading start reference point and the reading end reference point are arranged on the lower surface of the scale which is the arrangement reference of the document. In claim 3, claim 1 or 2
In the image reading apparatus described in the paragraph 1, the dimension between the reading start reference point and the reading end reference point is equal to or longer than the maximum reading document size in the sub-scanning direction. It is characterized by having done. In claim 4,
The image reading apparatus according to any one of claims 1, 2, and 3, wherein the distance from the document abutting member in the main scanning direction is x, and the distance from the document abutting member in the sub-scanning direction is y. It is characterized in that a reading start reference point is provided.

With the above structure, in claim 1, light is emitted from the light source to illuminate the original document to be read, and the reflected light or transmitted light is photoelectrically converted by the photoelectric conversion element, and the original document is read. In an image reading device that extracts image information as an electric signal, a dimension between a read start reference point and a read end reference point by a scan length difference calculation unit, and a read start reference point actually obtained by scanning by a photoelectric conversion element By comparing the dimension between the scanning end reference point and the scanning end reference point, and correcting the scanning length error of the image obtained by the photoelectric conversion element based on the scanning length difference by the correction unit. Even if the accuracy of the parts or the accuracy of the transmission body deteriorates due to changes over time, highly accurate image data can be obtained. According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, the reading start reference point and the reading end reference point are arranged on a lower surface of a scale serving as an arrangement reference of a document, so that a single member is formed. These read start position reference points and read end position reference points are arranged to prevent parts stacking errors, etc., to ensure a highly accurate reference interval, and to improve part accuracy and aging due to changes over time. Even if the accuracy of the transmitter decreases, high-accuracy image data can be obtained. According to claim 3, in the image reading device according to claim 1 or 2,
The dimension between the reading start reference point and the reading end reference point,
By setting the reference length to the outside of the original area by setting the same length or more to the length of the maximum read original size in the sub-scanning direction, it is possible to Highly accurate image data can be obtained even if the accuracy of parts and the accuracy of the transmission body are reduced due to aging and the like by reducing the calculation error. According to a fourth aspect, in the image reading apparatus according to any one of the first, second, and third aspects, the distance from the document abutting member in the main scanning direction is x, and the distance from the document abutting member in the sub-scanning direction is y. By providing the reading start reference point at the position, the distance between the origin of the original area and the reference point is defined to be a constant value for both main scanning and sub-scanning. The reading start position is accurately positioned so that high-accuracy image data can be obtained even if the parts accuracy and the accuracy of the transmission body deteriorate due to aging and the like.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is a perspective view showing an example of an image reading apparatus according to the present invention. In the image reading device 1 shown in this figure, an automatic paper feeding device 3 is rotatably mounted on an upper part of a main body 2 of a device around a support shaft (not shown) provided on the rear side (backward in FIG. 1) in the paper discharge direction. Attached, a paper discharge tray 4 is provided at the left end of the apparatus main body 2,
The original 5 is conveyed and read, and the original 5 is read by the apparatus main body 2
Two types of reading are possible, that is, reading by placing on the. FIG. 2 is a sectional view of the image reading device 1 shown in FIG. As shown in this figure, the main body 2 of the image reading apparatus 1 is provided with a document glass 6 on its upper surface. Further, inside the apparatus main body 2, a guide shaft (not shown) directed in the conveying direction of the document 5 (left and right direction in FIG. 2) and a guide rail (not shown) are parallel to the document glass 6. The two carriages are movably supported by these guide shafts and guide rails. At this time, one carriage (first carriage
The traveling body) has a light source 7 directed to the reading position A on the original glass 6 and a first mirror 8, and the other carriage (second traveling body) has a second mirror 9 and a third mirror 9. Mirror 10
And are installed. Although not shown, the light source 7 has a replaceable structure. Also, the third mirror 1
A lens 11 that converges the reflected light to form an image and a photoelectric conversion element 12 such as a CCD that reads the image is attached to a position facing the reflection surface of 0. In addition, the automatic paper feeding device 3 that constitutes the image reading device 1 includes
3, a paper feed roller 14 is provided along with
From the upper surface of the document placement surface 13, the document glass 6 of the apparatus main body 2
The conveyance path 15 that reaches the discharge tray 4 through the upper reading position A
A pair of upper and lower separation rollers 16 and a feed roller 17 are provided in the transport path 15, and a transport roller 18 is provided in the front in the transport direction. Further, a carrying roller 19 is provided on the front side of the reading position A, and a carrying roller pair 20 and a paper discharging roller pair 21 are provided behind the reading position A in the carrying direction.

FIG. 3 is a plan view showing a detailed configuration example of the first original document abutting member 35 and the second original document abutting member 36 provided on the original document glass 6 shown in FIG. As shown in this figure, one end side in the longitudinal direction of the original glass 6 that is inserted into the upper side of the apparatus main body 2 (one end side in the sub-scanning direction).
The first original document abutting member 35 is disposed on the first side, and the second original document abutting member 36 is disposed on one end side in the lateral direction of the original glass 6 (one end side in the main scanning direction).
As shown in FIG. 3, a reading start reference point 37 and a reading end reference point 38 are arranged on the back surface side of the second document abutting member 36. At this time, the reading start reference point 37 is located at a distance x, y from the origin of the original glass 6 (original of the original area) within the area outside the maximum size of the original 5 placed on the original glass 6. The read end reference point 38 is placed at a position separated by a distance Y from the read start reference point.

FIG. 5 is a block diagram showing an outline of a circuit configuration example of the image reading apparatus 1 shown in FIG. As shown in this figure, in the image reading apparatus 1, the document 5 is read from the host computer 24 via the interface 25 by the CPU.
26 by sending a command. When the manuscript 5 is read using the automatic paper feeder 3, when a necessary command is sent from the host computer 24 through the interface 25, C
The PU 26 performs data processing on the basis of the status of each part of the device output from the various sensor processing units 31 and the data stored in the ROM 27, while using the RAM 34 as a work area, and the data is stored in the motor drive circuit 28. A signal is sent, the motor 29 is driven, each carriage is moved to the document reading position, and the light source lighting device 30 is also
A signal is sent to turn on the light source 7. After the originals 5 are fed one by one to the conveyance path 15 by the paper feed roller 14, the separation roller 16, and the feed roller 17, and after passing the reading position A, after being read by the conveyance roller 19, the conveyance roller pair 20, and the discharge roller 21. The original document 5 is discharged onto the discharge tray 4. In the meantime, at the reading position A, the image reading unit 33 reads the image information on the original document 5 being conveyed, and the image processing unit 32 reads the image information obtained by this reading operation.
To process. That is, the light from the light source 7 is emitted to the original 5 on the original glass 6 at the reading position A, and the reflected light is sequentially reflected by the first mirror 8, the second mirror 9, and the third mirror 10 and is reflected by the lens 11. An image is formed on the photoelectric conversion element 12, and the image information on the original 5 is read. When the original 5 is read without using the automatic paper feeding device 3, the automatic paper feeding device 3 is rotated upward about the spindle to place the original 5 on the original glass 6. , The light source 7 by the motor 29
The carriage having the first mirror 8 and the carriage having the second mirror 9 and the third mirror 10 is moved in a direction parallel to the document surface to read an image.

Next, the operation of this embodiment will be described with reference to the flow chart shown in FIG. First, when the power of the image reading apparatus 1 is turned on, each unit of the apparatus is initialized by the CPU 26 (step ST1), and if any error occurs in this initialization processing (step ST).
2) This is detected by the CPU 26, the initialization process is performed again, and the error is removed (steps ST1 and ST2). When this initialization process is completed (step ST2), the CPU 26 controls the light source lighting device 30 to light the light source 7, and then the motor drive circuit 2
8 is controlled, the driving of the first and second traveling bodies is started, and the light source 7 arranged on the first traveling body and the first mirror 8 are moved to the reading start position. Is driven to move toward the reading end position from the first and second mirrors mounted on the first and second moving bodies, and the first original document abutting member is driven by the first mirror 8, the second mirror 9, and the third mirror 10. The image of the second document abutting member 35 and the second document abutting member 36 is captured and focused on the photoelectric conversion element 12 by the lens 11.

Next, the image signal output from the photoelectric conversion element 12 is processed by the CPU 26, and the image of the read start reference point 37 included in the image signal,
The image of the reading end reference point 38 is extracted, and the distances (the number of measurement lines) are calculated (step S
T3), the number of measured lines is compared with the preset number of set lines to calculate a difference (line number difference) n (step ST4), and when the line number difference n is a positive number. (Step ST5), some of the lines in the sub-scanning direction are set as overlapping lines (step ST6), and when the line number difference n is a negative number, the number of lines in the sub-scanning direction is set to be thinned. (Step ST7).
Accordingly, when the number of lines n is a positive number, the number of lines in the sub-scanning direction is set to be increased, and when the number of lines is a negative number, the number of lines in the sub-scanning direction is set to be decreased. It

Further, the CPU 26 detects the positions of the image of the read start reference point 37 and the image of the read end reference point 38 in the main scanning direction, and determines the position of the origin based on each of these position data. Each of these calculation results,
Correction data is created by the CPU 26 based on the detection result and is registered in the RAM 34. After this, when this process is completed, the normal document readable state is set,
The standby state is entered until the reading start switch is pressed. In this state, the automatic paper feeding device 3 is lifted, the original 5 to be read is placed on the original glass 6, and the end portion of the original 5 has the first original abutting member 35 and the second original abutting member 35. If the reading start switch is operated after the document 5 is positioned by being brought into contact with the contact member 36, the CPU 26
This is detected by, the light source lighting device 30 is controlled, and the light source 7 is turned on. Also, in parallel with this operation,
The motor drive circuit 28 is controlled by the CPU 26,
The driving of the first and second traveling bodies is started, the light source 7 arranged on the first traveling body and the first mirror 8 are moved to the reading start position, and from this position toward the reading end position side. The first mirror 8, the second mirror 9, and the third mirror 10 mounted on the first and second traveling bodies capture the image of the original 5 while being driven to travel.
The light is condensed on the photoelectric conversion element 12 by the lens 11.

Next, the number of lines of the image signal output from the photoelectric conversion element 12 is adjusted by the CPU 26 based on the setting content of the number of lines (either as it is, overlapping line or thinning out) obtained by the prescan operation. At the same time, the image signal for which the number of lines has been adjusted is subjected to image processing to create image data corresponding to the image of the document 5 and output to the outside of the apparatus. As described above, in this embodiment, the reading start reference point 37 and the reading end reference point 38 are arranged on the back surface of the second original document abutting member 36, and when the power source of the image reading apparatus 1 is turned on, the prescan is performed. The image of the read start reference point 37 and the image of the read end reference point 38 are extracted to perform the read start reference point 3
7 and the reading end reference point 38, the distance (the number of lines) is measured, and the number of reading lines when the image of the original 5 is read is adjusted based on the measurement result. Even if the accuracy and the accuracy of the transmission body decrease, it is possible to obtain highly accurate image data. Further, in this embodiment, the reading start reference point 37 and the reading end reference point 38 are arranged on the back surface of the second original document abutting member 36, so that a stacking error of parts does not occur. A high-accuracy reference interval can be obtained, which makes it possible to obtain high-accuracy image data even if the component accuracy or the accuracy of the transmission body deteriorates due to aging or the like.

Further, in this embodiment, since the reading start reference point 37 and the reading end reference point 38 are arranged outside the original area, the calculation error in correcting the image data can be reduced. This makes it possible to obtain high-accuracy image data even if the accuracy of parts and the accuracy of the transmission body deteriorate due to aging and the like. Further, in this embodiment, the distances between the origin of the document area, the read start reference point 37, and the read end reference point 38 are set to constant values x, y, Y for both main scanning and sub scanning. Therefore, the reading start position at the time of reading the image of the document 5 is accurately positioned, so that high-accuracy image data can be obtained even if the parts accuracy or the accuracy of the transmission member is deteriorated due to secular change or the like. You can

[0015]

As described above, according to the present invention, in claim 1, the reference points are arranged at the reading start position and the reading end position, so that the accuracy of parts and the transmission of the transmission member can be improved due to aging. Even if the accuracy decreases, it is possible to obtain highly accurate image data. According to the second aspect, by disposing the reference points indicating the reading start position and the reading end position on one member, it is possible to obtain a high-accuracy reference interval by preventing stacking errors of parts. As a result, even if the accuracy of the parts or the accuracy of the transmission body deteriorates due to secular change, it is possible to obtain highly accurate image data. According to the present invention, by arranging the reference points outside the original area, it is possible to reduce the calculation error when correcting the image data, and this reduces the accuracy of parts and the accuracy of the transmitter due to aging. Even in this case, highly accurate image data can be obtained. According to a fourth aspect of the present invention, in both main scanning and sub scanning, the distance between the origin of the original area and the reference point is defined to be a constant value, so that the reading start position when reading the image of the original is accurately positioned. As a result, even if the accuracy of the parts or the accuracy of the transmission body deteriorates due to secular change, it is possible to obtain highly accurate image data.

[Brief description of drawings]

FIG. 1 is a perspective view showing one example of an image reading apparatus according to the present invention.

FIG. 2 is a sectional view of the image reading apparatus shown in FIG.

FIG. 3 is a plan view showing a detailed configuration example of a first original document abutting member and a second original document abutting member provided on the original glass shown in FIG.

4 is a schematic cross-sectional view showing an example of arrangement positions of a read start reference point and a read end reference point provided in the image reading apparatus shown in FIG.

5 is a block diagram showing an outline of a circuit configuration example of the image reading apparatus shown in FIG.

6 is a flowchart showing an example of a scan length correction operation in the sub-scanning direction performed by the image reading apparatus shown in FIG.

[Explanation of symbols]

1 ... Image reading device, 2 ... Device body, 3 ... Automatic paper feeding device,
4 ... Paper discharge tray, 5 ... Original, 6 ... Original glass, 7 ... Light source, 8 ... First mirror, 9 ... Second mirror, 10 ... Third mirror, 11 ... Lens, 12 ... Photoelectric conversion element, 13 ... Original Placement surface, 14 ... Paper feeding roller, 15 ... Conveying path, 16 ... Separation roller, 17 ... Feeding roller, 18 ... Conveying roller, 19 ... Conveying roller, 20 ... Conveying roller pair, 21 ... Discharging roller pair, 24
… Host computer, 25… Interface, 26…
CPU (scan length difference calculation unit, correction unit), 27 ... ROM, 2
8 ... Motor drive circuit, 29 ... Motor, 30 ... Light source lighting device, 31 ... Various sensor processing units, 32 ... Image processing unit, 3
3 ... Image reading unit, 34 ... RAM, 35 ... First document abutting member, 36 ... Second document abutting member (scale), 3
7 ... Reading start reference point, 38 ... Reading end reference point

Claims (4)

[Claims] 1. An image in which light is emitted from a light source to illuminate a document to be read, and the reflected light or transmitted light is photoelectrically converted by a photoelectric conversion element to extract image information on the document as an electric signal. In the reading device, the reading start reference point that serves as the reference of the reading start position, the reading end reference point that serves as the reference of the reading end position, the dimension between the reading start reference point and the reading end reference point, and the photoelectric conversion element The scan length difference calculation unit that calculates the scan length difference by comparing the dimensions between the read start reference point and the read end reference point that were actually scanned, and the scan length difference calculation unit An image reading apparatus comprising: a correction unit that corrects a scanning length error of an image obtained by the photoelectric conversion element based on the scanning length difference. 2. The image reading apparatus according to claim 1, wherein the reading start reference point and the reading end reference point are arranged on a lower surface of a scale serving as a document arrangement reference. apparatus. 3. The image reading device according to claim 1, wherein a dimension between the reading start reference point and the reading end reference point is
An image reading apparatus having a length equal to or longer than the maximum reading document size in the sub-scanning direction. 4. The image reading device according to claim 1, wherein the distance from the document abutting member in the main scanning direction is x, and the distance from the document abutting member in the sub-scanning direction is y. An image reading apparatus, wherein the reading start reference point is provided at the position.