JP2000224385A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To read the image of an original without extension or contraction at an accurate timing without incurring the rise of a cost or the like by measuring the relation of the driving amount of a carrying member and the moving amount of the original based on the read result of a test sheet and controlling the drive of the carrying member of the original, based on a measured result. SOLUTION: The relation of the driving amount of the carrying member and the moving amount of the original is measured, based on the read result of the test sheet, and the drive of the carrying member of the original is controlled by using the measured result. In this image reader, the driving step numbers of the carrying member, after the test sheet 31 passes through a reference position until a read part reads the respective test images of a read start position and a read end position, are set as a read start timing and a read end timing. Thus, the timings are accurately set and the error of the relation of the driving amount of the carrying member and the moving amount of the original due to the individual difference of the dimension shape of the carrying member or the like is corrected. On the test sheet 31, a front part test image 32 and a rear part test image 33 are noted.

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 for reading an image of a document passing through a reading section while the document is being conveyed from a sheet feeding section via a reading section.

[0002]

2. Description of the Related Art In an image reading apparatus such as a copying machine or a facsimile, a single or a plurality of originals placed in a paper feeding section are conveyed one by one to a reading section, and the reading section reads an image of the original. There is something that I did. In such an image reading apparatus, in order to accurately read the image on the entire surface of the document, it is necessary to determine the image reading start timing based on the timing at which the front end of the document passes through the reading unit.

Therefore, in the conventional image reading apparatus, as shown in FIG. 7, a paper feed sensor 62 for detecting a state where a document is set on a document tray 61 constituting a paper feeding unit, and a document set on the document tray 61. Paper feed roller 63 that contacts the lower end of the document, reading unit 64 that reads the image of the document, platen roller 65 that faces reading unit 64, and platen roller 65 that is between paper feed roller 63 and platen roller 65 A document sensor 66 for detecting a document at a position where the document is to be moved.

In this configuration, when the paper feed sensor 62 detects that a document has been set on the document tray 61, the supply of rotational force to the paper feed roller 63 and the platen roller 65 is started, and the document sensor 66 detects the front end of the document. After a lapse of a predetermined time from when the document is detected to when the front end of the document comes into contact with the platen roller 65, the driving of the paper feed roller 63 is stopped, and the rotation of the platen roller 65 reads the vicinity of the front end of the document. Unit 64 and platen roller 6
5, the image reading is started.

That is, in the conventional configuration, the reading unit 64
A document sensor 66 is arranged at a predetermined distance from the reading position at which the document sensor 66 and the platen roller 65 are opposed to each other, and the document sensor 66 is rotated based on the timing at which the document sensor 66 detects the front end of the document. Thus, when the front end of the document has moved a predetermined distance between the document sensor 66 and the reading position is determined as the image reading start timing.

The period during which the front end of the original moves a predetermined distance between the original sensor 66 and the reading position is, for example, a stepping operation for supplying rotation to the feed roller 63 after the original sensor 66 detects the front end of the original. The number of drive steps of the motor can be set in advance by calculating from the predetermined distance and the diameter of the paper feed roller 63.

[0007]

However, in the above-mentioned conventional configuration, the paper feed roller 63 and the platen roller 65 are not provided.
When the timing at which the stepping motor is driven by a predetermined number of steps after the document sensor 66 disposed between the document sensor 66 detects the front end of the document is set as the image reading start timing, the reading unit 64 and the document sensor 66 And the number of driving steps of the stepping motor necessary for the front end of the document to move between the document sensor 66 and the reading position fluctuates due to the dimensional error between the sheet feeding roller 63 and the dimensional error. The front end of the original is the original sensor 6
6, the moving distance cannot be made constant, and the timing at which the front end of the document faces the reading unit 64 and the timing at which image reading is started may not be exactly the same. There is a problem that reading cannot be performed accurately.

[0008] Such a problem similarly occurs in determining the image reading end timing. That is, the image reading end timing is determined based on the number of driving steps of the stepping motor that supplies rotation to the platen roller 65.
After the original sensor 66 detects the passage of the rear end of the original, the platen roller 6 is moved by a distance from the installation position of the original sensor 66 to a position where the rear end of the original should face when reading of the image is completed.
When the number of steps for moving the peripheral surface of the platen 5 or the number of steps for moving the peripheral surface of the platen roller 65 by the length of the image reading range in the sub-scanning direction after the start of image reading is set. If the movement amount of the peripheral surface of the platen roller 65 per one step of the stepping motor fluctuates due to an error in the diameter of the platen roller 65, the reading end timing also changes, and the image reading range cannot be made constant. There is a problem that an image cannot be read accurately.

In this case, a specific pattern is printed on the surface of the plate-like member facing the reading unit with the document interposed therebetween, and the specific pattern is printed depending on whether the specific pattern exists in the image data read by the reading unit. In the configuration disclosed in Japanese Patent Application Laid-Open No. 4-372273, in which the document transport position is determined, the front end and the rear end of the document are determined based on the determination result as to whether the document is facing the reading unit. Although it is possible to detect the timing facing the reading unit, it is not possible to detect the timing when a specific position in the sub-scanning direction in the document faces the reading unit.

For this reason, even in the configuration disclosed in Japanese Patent Application Laid-Open No. 4-372273, the reading start position and the reading end position are set at positions inside the front end and the rear end of the document by a predetermined length. In this case, the timing at which the reading unit opposes the reading start position and the reading end position of the document from the timing at which the front end of the document is detected is controlled based on the moving amount of the document by a conveying member such as a paper feed roller or a platen roller. When the relationship between the driving amount of the conveying member and the moving amount of the document changes due to an error in the shape and dimension of the conveying member, the reading unit accurately detects the timing of facing the reading start position and the reading end position of the document. As a result, the image reading range fluctuates and the image on the document cannot be read accurately.

From these facts, the image reading start position,
In order to match the reading end position and the image reading range with the design values, it is necessary to maintain strict dimensional accuracy and mounting position accuracy of the conveying member and the driving mechanism, which increases the component cost and the manufacturing cost, and increases the manufacturing work. Is complicated.

An object of the present invention is to measure a relationship between a driving amount of a conveying member and a moving amount of a document based on a reading result of a test sheet in which a specific pattern is written, and use the measurement result to convey a document conveying member. Controls the read start timing and the read end timing with reference to the timing at which a document passes through a specific position in the transport path, and makes the actual image reading range exactly match the design value. Error in the relationship between the amount of drive of the transport member and the amount of movement of the document due to individual differences in the dimensions and shape of the transport member, thereby increasing component costs and manufacturing costs, and without complicating the manufacturing operation. It is an object of the present invention to provide an image reading apparatus capable of reading an image at an accurate timing without expansion and contraction.

[0013]

According to a first aspect of the present invention, there is provided an image reading apparatus for conveying an original from a paper feeding unit via a reading unit by driving a conveying member and reading an image of the original passing through the reading unit. In the test mode, a test sheet carrying a test image indicating a reading start position and a reading end position is conveyed in a test mode, and after the test sheet has passed a reference position, the reading unit performs a test for each of the reading start position and the reading end position. The method is characterized in that the number of driving steps of the conveying member until the image is read is measured, and the measurement result is set as a reading start timing and a reading end timing.

According to the first aspect of the present invention, the number of driving steps of the transport member after the test sheet passes through the reference position and before the reading section reads the respective test images at the reading start position and the reading end position is reduced. The timing is set as the reading start timing and the reading end timing. Therefore, the reading start timing and the reading end timing are set accurately with reference to the timing at which the document passes the specific position in the transport path, and the actual image reading range is made to exactly match the design value so that the transport member An error in the relationship between the driving amount of the conveying member and the moving amount of the document due to individual differences in size and shape is corrected, and the image of the document is accurately read.

According to a second aspect of the present invention, there is provided an image reading apparatus for conveying an original from a paper feeding unit via a reading unit by driving a conveying member and reading an image of the original passing through the reading unit in a test mode. A test sheet on which a test image indicating the front end position and the rear end position of the error extraction distance in the sub-scanning direction is conveyed, and the reading unit reads the test image at the front end position of the error extraction distance, and then reads the test image at the rear end position. The number of driving steps of the conveying member until reading is performed is measured, and a value calculated by comparing the measured value with a design value is set as a correction value of the data amount.

According to the second aspect of the present invention, the data is read based on the number of driving steps of the conveying member from when the reading unit reads the test image at the front end position of the error extraction distance to when the test image at the rear end position is read. A correction value for the quantity is set. Therefore, an error in the relationship between the driving amount of the conveying member and the moving amount of the document due to individual differences in the size and shape of the conveying member, etc.
The correction is performed based on the result of comparison between the measured value of the number of drive steps of the conveying member and the design value while the test sheet moves the error extraction distance, and the image of the document is read without expansion and contraction.

According to a third aspect of the present invention, the test image of the test sheet includes a test image at each of a front end position and a rear end position of an error extraction distance in the sub-scanning direction,
While transporting one test sheet in the test mode,
A process of setting the measurement result of the number of driving steps of the conveying member until the reading unit reads the test image at the reading start position after the test sheet passes the reference position as a reading start timing, and the reading unit sets a front end of the error extraction distance. A process of setting a correction value of the data amount based on the number of drive steps of the transport member after reading the test image at the position until reading the test image at the rear end position, and reading after the test sheet has passed the reference position A process of sequentially setting a measurement result of the number of drive steps of the transport member until the unit reads the test image at the reading end position as a reading end timing is sequentially executed.

According to the third aspect of the present invention, a reading start timing, a data amount correction value, and a reading end timing are set while one test sheet is conveyed in the test mode. Therefore, data necessary for reading an image of a document at an accurate timing without expansion and contraction is quickly set.

According to a fourth aspect of the present invention, the reading section executes a thinning process or an interpolation process of an image in the sub-scanning direction of the image data read from the document based on the correction value of the data amount. And

According to the fourth aspect of the present invention, based on the data amount correction value set in the test mode,
A thinning process or an interpolation process is performed on an image in the sub-scanning direction of image data read from a document. Therefore,
Even when the relationship between the drive amount of the transport member and the movement amount of the document due to individual differences in the size and shape of the transport member and the like fluctuates, the image of the document can be accurately read without expansion and contraction.

[0021]

FIG. 1 is an external view of a facsimile which is an image reading apparatus according to an embodiment of the present invention. A facsimile 1 according to an embodiment of the present invention includes an operation unit 2 on an upper surface and a document tray 3 and a paper tray 4 mounted thereon. In addition, a paper discharge tray 5 is mounted on the front surface of the facsimile 1. In this facsimile 1, one or a plurality of originals are set on the original tray 3 in a state where the vicinity of the lower end is inserted into the inside from the opening 6 on the upper surface. Documents set on the document tray 3 are conveyed one by one by rotation of a feed roller described later. The facsimile 1 internally reads an image of a document by a reading unit described later, and transmits the read image as transmission data to a destination facsimile via a public telephone network. On the other hand, when the facsimile 1 receives the fax data via the public telephone line network, the facsimile 1 feeds the recording paper set in the paper tray 4 one by one into the inside, and an image based on the fax data is formed on the surface of the recording paper. Perform formation.

FIG. 2 is a schematic side sectional view showing the structure of the main part of the facsimile. Inside the facsimile 1, a paper feed sensor 11 for detecting the lower end of the original set on the original tray 3, a paper feed roller 12 contacting the lower end of the original, a reading unit 13 for reading the image of the original, a reading unit 13 And a document sensor 15 for detecting a document between the sheet feeding roller 12 and the platen roller 14 are disposed between the document tray 3 and the discharge tray 5 via the reading unit 13. A document conveyance path 16 is formed between the two. The paper feed roller 12 rotates by receiving a rotational force from a paper feed motor 17 which is a stepping motor, and feeds a single or a plurality of originals set on the original tray 3 one by one into the original transport path 16. Paper. The platen roller 14 rotates by receiving a rotational force from a reading motor 18 which is a stepping motor, and rotates the document fed from the document tray 3 in the direction of the discharge tray 5 while bringing its image surface into contact with the reading unit 13. Transport to During this time, the image of the original is read by the reading unit 13, and the original whose image has been read is discharged onto the discharge tray 5. The reading unit 13 and the platen roller 14
The reading unit of the facsimile 1 is configured.

FIG. 3 is a diagram showing an image reading range of a document in the facsimile. In the facsimile 1 according to this embodiment, for example, when the reading resolution in the sub-scanning direction is 200 dpi, an image is read at a scanning line density of n = 8 lines / mm, and the length in the sub-scanning direction is 2
In an A4 size document that is 96 mm, the position inside 2 mm from the front end is set as the reading start position, and 2 m from the rear end.
The position inside m is the reading end position. Therefore,
The image reading range L of the A4 size document in the sub-scanning direction is L = 297-2-2 = 292 mm. Further, the number N of scanning lines in the A4 size image reading range is N = 292 × 8 = 2336 lines. When the front end of the document is the first line, the scanning start position is the 17th line to the 2352nd line. Read the image data of the document.

FIG. 4 is a block diagram showing the configuration of the control unit of the facsimile. The control unit of the facsimile 1
An image memory 24, an operation unit 2, a paper feed sensor 11, a document sensor 1
5, input / output devices including a paper feed motor 17, a reading motor 18, a CCD 27 and an exposure lamp 28 are connected. The CCD 27 and the exposure lamp 28 are provided in the reading unit 13. The CPU 21 controls and controls each input / output device in accordance with a program written in the ROM 22 in advance, and transfers data input / output during this time to the RA.
It is stored in a predetermined memory area of M23. CPU 21
After storing the image data of the original read through the CCD 27 in the image memory 24, the image data is output to a modem or an image forming unit (not shown).

The ROM 22 can be written at least once. However, writing data to the ROM 22 may be unnecessary by providing the RAM 23 with a battery back or by providing another nonvolatile memory.

FIG. 5 is a diagram showing a test sheet used for processing the test mode of the facsimile machine.
The test sheet 31 has, for example, a front test image 32 and a rear test image 33 written near the front end and the rear end on the surface of an A4-size white flexible resin sheet. In this example, the front test image 32 is
The width is 1 mm in the sub-scanning direction (Y direction), and the width of the main scanning direction (X direction) is symmetrical. . Further, the rear test image 33 is a figure having a vertically symmetric shape with respect to the front test image 32.

As described above, when the reading start position and the reading end position of the image are 2 mm inside from the front end and the rear end of the original, the reading start position of the test sheet 31 is It is located between the second rectangle and the third rectangle, and the reading end position is the rear test image 33.
Is located between the third rectangle and the fourth rectangle. The error extraction distance E, which is the length in the sub-scanning direction between the front test image 32 and the rear test image 33 on the test sheet 31, is 286 mm.
There are 6 × 8 = 2288 read lines.

The test image described on the test sheet 31 is not limited to the shape of this embodiment, and is at least for each minimum adjustment length (for example, 1 mm interval) of the reading start position and the reading end position in the sub-scanning direction. If the shape in the main scanning direction changes, a plurality of types of reading start positions and reading end positions can be determined by one type of test sheet 31. Further, since the front test image 32 and the rear test image 33 are vertically symmetrical, even if the test sheet 31 is set on the document tray 2 with either the front end side or the rear end side of the test sheet 31 downward, it will be described later. The processing in the test mode can be properly executed.

FIG. 6 is a flowchart showing a processing procedure in the test mode of the control unit of the facsimile apparatus. In the test mode, the CPU 21 sets the test sheet 31 on the document tray 3 and
When 1 is turned on (s1), the sheet feeding motor 17 and the reading motor 18 are driven (s2, s3), and the document sensor 15 waits until the front end of the test sheet 31 is detected (s2).
4). The CPU 21 determines that the original sensor 15 is
When the front end of 1 is detected and turned on, counting of the number of driving steps of the sheet feeding motor 17 and the reading motor 18 by the counter C assigned to a predetermined memory area of the RAM 23 is started (s5).

Thereafter, the CPU 21 reads the reading unit 13
In the read image, the count value Ca of the counter C when the width of the front test image 32 of the test sheet 31 is expanded twice is read, and the count value Ca can be written as the read start timing Ta in the memory area MA1 of the ROM 22. (S6, s7). Further, the CPU 21 sets a counter C when the image of the front test image 32 of the test sheet 31 is not present in the image read by the reading unit 13.
Is read and stored in a predetermined memory area of the RAM 23 (s8, s9).

Next, the CPU 21 reads the reading unit 13
(C10, s11) of the counter C when the rear test image 33 of the test sheet 31 appears in the read image (s10, s11), and the error value M is calculated by M = (Cc−Cb) / E · n ( s12). In the above equation, E is an error extraction distance (286 mm), and n is a design value (8 lines / mm) of scanning line density. The CPU 21 stores the calculated error value M in the memory area MA2 of the ROM 22 (s13).

Further, the CPU 21 reads the reading unit 13
In the read image, the count value Cd of the counter C when the width of the rear test image 33 of the test sheet 31 is reduced three times is read, and the count value Cd is stored in the memory area MA3 of the ROM 22 as the read end timing Tb (s1).
4, s15).

The CPU 21 drives the feed motor 17 and the read motor 18 after the original sensor 15 detects the front end of the original fed from the paper feed tray 2 when reading an image of a normal original in the facsimile 1. Starts the process of storing the image data read by the reading unit 13 in the image memory 24 after the predetermined image processing when the number of steps matches the number of steps stored as the reading start timing Ta. This processing ends when the number of steps matches the number of steps stored as the end timing Tb.

Further, the CPU 21 adds an error value M to the image data stored in the image memory 24 in this manner.
Thinning processing or interpolation processing based on. For example, the measured value of the number of drive steps within the error extraction distance E in the test mode is 2357, which is 3% of the set value 2288.
If it is excessive, a thinning process is performed to delete three lines of images for every 100 lines from the image data stored in the image memory 24. Also, the measured value of the number of drive steps within the error extraction distance E in the test mode is 2219,
If the setting value is 2% less than the set value 2288, an interpolation process of adding an image of three lines for every 100 lines is performed on the image data stored in the image memory 24.

As described above, in the facsimile 1 according to this embodiment, the test sheet 31
Is performed, and the reading start timing Ta and the reading end timing Tb are determined based on the timing at which the document sensor 15 detects the front end of the test sheet 31 by the number of driving steps of the sheet feeding motor 17 and the reading motor 18. The measurement is performed, and the measurement result is stored. The error value M is obtained by comparing the measured value of the number of driving steps within the error extraction distance E on the test sheet 31 with the design value.
Is calculated and stored. At the time of image reading processing of a normal document, image processing is controlled based on the number of driving steps of the sheet feeding motor 17 and the reading motor 18 using the reading start timing Ta, the reading end timing Tb, and the error value M stored in the test mode. I do.

Therefore, due to dimensional errors and mounting position errors of the paper feed roller 12 and the platen roller 14 and the transmission mechanism that supplies the rotation of the paper feed motor 17 and the read motor 18 to these, the paper feed motor 17 and the read motor 18
Even if the document transport distance per unit drive step does not match the design value, an image without expansion and contraction can be reliably read from the document at an accurate timing.

Note that the above-described test mode processing is performed not only once before the facsimile 1 is shipped, but also
Read start timing T obtained in the latest test mode by repeatedly executing at an arbitrary timing during use
a, the reading end timing Tb and the error value M may be stored in an up-to-date manner so as to correct errors due to aging of the apparatus.

The image reading apparatus is not limited to a facsimile, and the present invention can be similarly applied to other image reading apparatuses such as a copying machine for reading an image of a document conveyed to a reading section.

[0039]

According to the first aspect of the present invention, the driving of the transport member after the test sheet passes the reference position and before the reading section reads the respective test images at the reading start position and the reading end position. By setting the number of steps as the reading start timing and the reading end timing, the reading start timing and the reading end timing can be accurately set based on the timing at which the document passes the specific position in the transport path, and the actual image reading range can be set. Is accurately matched with the design value to correct the error in the relationship between the driving amount of the conveying member and the moving amount of the document due to individual differences in the size and shape of the conveying member, etc., and read the image of the document at an accurate timing. be able to.

According to the second aspect of the present invention, the reading unit reads the test image at the front end position of the error extraction distance and then reads the test image at the rear end position based on the number of driving steps of the transport member. By setting a correction value for the data amount, errors in the relationship between the drive amount of the transport member and the amount of movement of the document due to individual differences in dimensions and shape of the transport member, etc., can be conveyed while the test sheet moves the error extraction distance Correction can be made based on the result of comparison between the measured value of the number of drive steps of the member and the design value, and the image of the document can be read accurately without expansion and contraction.

According to the third aspect of the present invention, the reading start timing, the data amount correction value, and the reading end timing are sequentially set while one test sheet is being conveyed in the test mode, so that the original can be read. It is possible to quickly set data necessary for reading an image at an accurate timing without expansion and contraction.

According to the fourth aspect of the present invention, the thinning process or the interpolation process for the image in the sub-scanning direction of the image data read from the document is performed based on the correction value of the data amount set in the test mode. By doing so, even when the relationship between the drive amount of the transport member and the movement amount of the document due to individual differences in the size and shape of the transport member and the like changes, the image of the document can be read accurately without expansion and contraction.

[Brief description of the drawings]

FIG. 1 is an external view of a facsimile which is an image reading apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic side sectional view showing a configuration of a main part of the facsimile.

FIG. 3 is a diagram showing an image reading range of a document in the facsimile.

FIG. 4 is a block diagram showing a configuration of a control unit of the facsimile.

FIG. 5 is a diagram showing a test sheet used for processing in a test mode of the facsimile machine.

FIG. 6 is a flowchart showing a processing procedure in a test mode of a control unit of the facsimile apparatus.

FIG. 7 is a schematic side sectional view showing a configuration of a main part of a conventional facsimile.

[Explanation of symbols]

 1-facsimile (image forming apparatus) 3-document tray 5-discharge tray 11-feed sensor 12-feed roller 13-reading unit 14-platen roller 15-document sensor 16-document transport path 17-feed motor 18 -Reading motor 27-CCD 28-Exposure lamp

Claims (4)

[Claims] An image reading apparatus for conveying an original from a paper feeding unit via a reading unit by driving a conveying member and reading an image of the original passing through the reading unit. The number of driving steps of the conveying member between the time when the test sheet carrying the test image indicating the position is conveyed and the reading unit reads the respective test images at the reading start position and the reading end position after the test sheet has passed the reference position. , And sets the measurement result as a reading start timing and a reading end timing. 2. An image reading apparatus which conveys an original from a paper feeding unit via a reading unit by driving a conveying member and reads an image of the original passing through the reading unit. A conveying member that conveys a test sheet on which a test image indicating the front end position and the rear end position of the distance is written, and that the reading unit reads the test image at the front end position of the error extraction distance and then reads the test image at the rear end position. An image reading apparatus characterized in that the number of driving steps is measured, and a value calculated by comparing the measured value with a design value is set as a data amount correction value. 3. The test image of the test sheet includes a test image at each of a front end position and a rear end position of an error extraction distance in a sub-scanning direction. The process of setting the measurement result of the number of drive steps of the conveying member until the reading unit reads the test image at the reading start position after passing the reference position as the reading start timing, and the reading unit sets the front end position of the error extraction distance. A process of setting a correction value of the data amount based on the number of driving steps of the conveying member until the test image at the rear end position is read after the test image is read, and a reading unit after the test sheet passes the reference position. A process of setting the measurement result of the number of driving steps of the transport member until the test image at the reading end position is read as the reading end timing. The image reading apparatus according to claim 1 to be executed. 4. The image reading device according to claim 2, wherein the image reading unit performs a thinning process or an interpolation process in the sub-scanning direction of the image data read from the document based on the correction value of the data amount. apparatus.