JP2000059621A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the operation to decide an adjustment value for shading correction by reading a 1st side, a 2nd side of an original that is being carried, a reference white level for the 1st side and a reference white level for the 2nd side so as to decide the adjustment value for shading correction. SOLUTION: The image reader consists of a circuit of the reader main body and a circuit of an ADF 100. An analog image signal photoelectrically converted by a close contact image sensor 15 of the circuit of the ADF 100 is transferred to a reverse side sensor board unit 16, where the signal is digitized and shading is corrected. Then an adjustment value for shade correction for the 1st side of an original is decided so that a density of the 1st side of the original read by a 1st read means in this reader is nearly equal to a density of a reference white level for the 1st side. Furthermore, an adjustment value for shade correction for the 2nd side of the original is decided so that the density of the 2nd side of the original read by a 2nd read means in this reader is nearly equal to the density of a reference white level for the 2nd side.

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 having a function of determining an adjustment value for performing shading correction on both sides of a document using a white reference plate and a white sheet.

[0002]

2. Description of the Related Art In an image reading apparatus for reading an original,
Generally, by adjusting the reference voltage of a converter for A / D-converting a read signal, the background of a document can be removed. If the densities of the backgrounds of the first and second surfaces of the document are different, the reference voltage of each converter for A / D converting each of the read signals of the first and second surfaces of the document is adjusted. There must be.

FIG. 6 shows an image reading apparatus having an ADF 100 that conveys both sides of a document so as to be readable, and FIG. 7 shows a main part of the ADF 100. As shown in FIG. 7, the home position HP of the reading optical system is the first surface reading position B and the white reference plate 17 in the duplex mode.
It is located on the right side in the figure from a. When reading a document placed on the document glass 1, the reading optical system travels in the sub-scanning direction A. That is, in FIG. 6, the first traveling body on which the first mirror 2 and the illumination lamp 3 are mounted and the second traveling body on which the second mirror 4 and the third mirror 5 are mounted are 2: 1 by the traveling motor 7. The vehicle travels in the sub-scanning direction A at a speed ratio.
7a and the document surface placed on the platen glass 1 are illuminated by the illumination lamp 3, the reflected light is reflected by the first mirror 2, the second mirror 4 and the third mirror 5, and the light receiving surface of the CCD 6 by the lens 31. And is read by the CCD 6. Reference numeral 20 denotes a sensor board unit on which the CCD 6 is mounted.

On the other hand, when reading both sides while the original is running using the ADF 100, the reading optical system moves from the home position HP to the position of the white reference plate 17a and reads the first side. When it is moved to the position B and read therefrom, it is fixed at the position B. The originals (not shown) stacked on the original tray 8 are taken in one by one by the pickup roller 9,
Next, the sheet is conveyed to the first surface reading position B by the registration roller pair 10, the conveyance drum 11, and the conveyance roller 12, and the first surface is read by the CCD 6, and then the contact image sensor 15 and the pair The second surface is conveyed to the color roller 17 and the second surface is in close contact with the image sensor 1.
5, and is discharged onto a discharge tray 32 via a pair of transport rollers 13, an endor unit 18 and an endor platen 19 for printing characters, and a pair of discharge rollers 14.

The contact image sensor 15 is a light source LE
D, a lens, and a reading sensor are mounted on the reverse side sensor board unit 16. Therefore, both sides can be read by running the document only once. Also, the color roller 17
Is provided so as to face the contact image sensor 15,
Further, the entire surface is white and is constantly rotating during document conveyance. Therefore, the contact image sensor 15 can read the color roller 17 before reading the second surface.

FIG. 8 shows a conventional example for performing shading correction on both sides of a document. Here, each read signal read by the CCD 6 and the contact image sensor 15 is converted into digital data by each A / D converter according to the reference voltage. The reference voltage of each A / D converter can be changed from the CPU via the D / A converter.

FIG. 8A shows the processing of the first surface. In this process, first, the traveling body on which the light source 3 and the mirrors 2, 4, and 5 are mounted is moved to the reading position of the reference white plate 17a (step S1), and the reference white data D1 on the reference white plate 17a is converted to C.
The data is read via the CD 6 and its A / D converter (step S2). Next, the traveling body is moved in the sub-scanning direction (step S3), and the white data D2 of the first surface of the reference document on the platen glass 1 is read via the CCD 6 and its A / D converter (step S4).

Thereafter, it is determined whether or not the reference white data D1 and the original white data D2 are within an error range (step S5).
If the error is not within the error range, the reference voltage of the A / D converter (the adjustment data DAC1 for the D / A converter) is changed and the white data D2 of the first surface of the reference document is read again (steps S6 → S4). . This process is repeated until the reference white data D1 and the original white data D2 fall within the range of the error to determine the final adjustment setting value DAC1 for the first surface, and store it in the RAM (step S7).

FIG. 8B shows the processing of the second surface. In this process, first, the conveyance of the reference document on the document tray 8 is started (step S11), and the white data D3 on the color roller 17 is read via the contact image sensor 15 and its A / D converter (step S11). S12). Next, it is determined whether or not the reference original has reached the second-side reading position C (step S13). When the reference original has reached, the white data D4 of the second side of the reference original is transmitted via the contact image sensor 15 and its A / D converter. And read it (step S14).

Thereafter, it is determined whether or not the color roller white data D3 and the reference original white data D4 are within an error range (step S15). If not, the reference voltage (A / D converter) of the A / D converter is determined. The adjustment data DAC2) for the D / A converter is changed to change the white data D4 of the second surface of the reference original.
Is read (step S16 → S14). Then, this process is performed by matching the color roller white data D3 with the reference original white data D4.
Is repeated until the value falls within the range of the error, the final adjustment setting value DAC2 for the second surface is determined, and this is stored in the RAM (step S17).

As a conventional example of this kind, the invention disclosed in, for example, JP-A-6-54188 is known. According to the present invention, in an image reading apparatus that performs shading correction using a white reference plate and blank paper, data obtained by reading blank paper is stored in a memory in advance so that shading correction can be performed without blank paper, and shading correction is performed. In some cases, blank data stored in the memory is used instead of reading blank paper.

[0012]

However, in the above conventional example, the adjustment setting value DAC1 for shading correction on the first surface is determined by the original on the original platen glass 1, and the second surface is determined by the original on the original tray 8. Is set on the platen glass 1 to read the first side of the document, and then the ADF 10 is set to read the second side.
However, there is a problem that the operation must be complicated because the document must be set on the original tray 8 of the printer.

In view of the above-mentioned problems of the prior art, the present invention can simplify the operation when determining the adjustment value for shading correction by comparing the first and second surfaces of a document with reference white. It is an object to provide an image reading device.

[0014]

According to a first aspect of the present invention, there is provided an image reading apparatus for optically reading a document conveyed by a document conveying means. First reading means for reading the first face and the reference white for the first face, second reading means for reading the second face and the reference white for the second face of the document conveyed by the document conveying means, Determining an adjustment value for shading correction for the first surface of the document so that the first surface of the document read by the first reading unit and the reference white density for the first surface are substantially the same; Control means for determining an adjustment value for shading correction for the second surface of the document such that the second surface of the document read by the second reading device and the reference white density for the second surface are substantially the same; Characterized by having

The second means is to achieve the above object,
In an image reading apparatus for optically reading a document conveyed by a document conveying means, a first reading means for reading a reference white common to the first surface, the first surface and the second surface of the document conveyed by the document conveying means The second reading means for reading the second surface of the document conveyed by the document conveying means, and the reference white density common to the first surface of the document read by the first reading means being substantially the same. An adjustment value for shading correction for the first side of the document is determined so that the second side of the document read by the second reading unit and the common reference white read by the first reading unit. And control means for determining an adjustment value for shading correction for the second surface of the document such that the densities are substantially the same.

The third means is to achieve the above object.
In an image reading apparatus for optically reading a document conveyed by a document conveying means, a first reading means for reading a reference white common to the first surface, the first surface and the second surface of the document conveyed by the document conveying means The second reading means for reading the second surface of the document conveyed by the document conveying means, and the reference white density common to the first surface of the document read by the first reading means being substantially the same. An adjustment value for shading correction for the first side of the document is determined so that the second side of the document read by the second reading unit and the common reference white read by the first reading unit. And control means for determining an adjustment value for shading correction for the second surface of the document so that the predetermined density difference becomes a predetermined density difference.

The fourth means has a nonvolatile memory for storing the adjustment value for shading correction determined by the control means in the first to third means.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an image reading apparatus according to the present invention, and FIG.
FIG. 3 is a block diagram showing a main part of the scanner control unit, and FIG. 3 is a flowchart for explaining a process of determining an adjustment value for shading correction of the image reading apparatus of FIG.

The circuit shown in FIG. 1 is roughly constituted by the circuit of the apparatus main body and the circuit of the ADF 100. First,
The circuit of the apparatus main body will be described in detail. In the SBU (Sensor Board Unit) 20, the reflected light of the original enters the CCD 6 shown in FIG. 6 and is converted by the CCD 6 into an analog signal having a voltage value corresponding to the intensity of the light. Divided for even bits. This signal is then subjected to analog processing to remove the dark potential,
Next, each signal of the odd bit and the even bit is synthesized.
Next, the gain is adjusted to a predetermined amplitude and converted into a digital image signal by an A / D converter, and this digital image signal is transmitted via an IOB (I / 0 board) 24 to the SCU.
(Scanner control unit) 21.

In the SCU 21, this digital image signal is
After being subjected to shading correction, gamma correction, MTF correction, and the like by a PU (image processing unit) 33, it is binarized, and together with a page synchronizing signal, a line synchronizing signal, and an image clock as a video signal, through a selector (not shown). The signal is applied to the option IPU 26 via a SiBC (scanner image buffer controller) 35 or a connector 34. Option IPU26
In, predetermined image processing is performed on the input video signal,
Next, the SiBC3 is transmitted through the selector in the SCU 21.
5 is applied. In the SiBC 35, a video signal input from the IPU 33 or the optional IPU 26 is stored in an image memory (DRAM) 35a. This video signal is S
The data is transferred to an external device such as a personal computer (host computer 102 shown in FIG. 2) via the CSI controller 36.

Next, the circuit of the ADF 100 will be described in detail. The contact image sensor (CI shown in FIGS. 6 and 7)
The analog image signal photoelectrically converted by the S: contact image sensor 15 is transferred to an RSBU (reverse side sensor board unit) 16 and digitized, and then subjected to shading correction. This digital image signal is transferred to the RCU 23 on the apparatus main body side. The RCU 23 has an image memory composed of DRAM and SiBC for controlling this image memory.
Temporarily stores the digital image signal from the
Transfer to CU21. In the SCU 21, the digital image signal from the RCU 23 or from the SiBC 35 is switched and transferred to the host computer 102 via the SCSI controller 36.

Here, the SCU 21 also includes a CPU 37, a ROM 38, and a RAM 39 as shown in detail in FIG.
And an EEPROM 40 are provided.
Communication with the host computer 102 is performed by controlling the controller 36. The CPU 37 also includes a traveling body motor 7 that is a stepping motor, a paper feed motor,
Controls the timing of the transport motor. An ADU (ADF driving unit) 30 relays power supply to power transmission components used in the ADF 100.

The input port of the CPU 37 is IOB2
4 are connected to a main body operation panel 28 and an optional operation panel 29. The main body operation panel 28 is provided with a start switch, an abode switch, and the like. When each switch is pressed, the CPU 37 detects this through an input port. A PSU (power supply unit) 25 and a network controller 27 are also provided on the main body side.

As shown by the dotted line in FIG.
The PU 37, the ROM 38, and the RAM 39 may be provided in the RCU 23 to perform double-sided reading control. Also, instead of the contact image sensor 15 for reading the second surface, CC
D may be used.

Next, a process for determining an adjustment value for shading correction on both sides of a document will be described with reference to FIG. The reference original is set on the original tray 8 instead of the original platen glass 1. First, the traveling body on which the light source and the mirror are mounted is moved to the reading position of the reference white plate 17a shown in FIG. 7 (step S21), and the reference white data D11 on the reference white plate 17a is transferred via the CCD 6 and its A / D converter. Is read (step S22). Next, the traveling body is moved and fixed to the first surface reading position B (step S23), and conveyance of the reference document is started (step S24), and it is determined whether or not the reference document has reached the first surface reading position B. Then, when it arrives, the white data D22 of the first surface of the reference document is read via the CCD 6 and its A / D converter (step S26).

Next, it is determined whether or not the reference white data D11 and the original white data D22 are within an error range (step S2).
7) If the error is not within the range of the error, the reference voltage of the A / D converter (adjustment data DAC for the D / A converter)
1) is changed and the white data D22 of the first side of the reference document is read again (steps S28 → S26). This process is repeated until the reference white data D11 and the original white data D22 fall within the range of the error, thereby determining the final adjustment setting value DAC1 for the first surface, and storing it in the EEPROM 40 (step S29).

Next, the white data D33 on the color roller 17
Is read via the contact image sensor 15 and its A / D converter (step S30). Then the reference manuscript is
It is determined whether or not the surface reading position C has been reached (step S31), and when it has reached, the white data D4 of the second surface of the reference document has been reached.
4 is read via the contact image sensor 15 and its A / D converter (step S32).

Thereafter, it is determined whether or not the color roller white data D33 and the reference original white data D44 are within the range of error (step S33). If not, the reference voltage of the A / D converter (step S33). The adjustment data DAC2 for the D / A converter is changed, and the white data D44 of the second surface of the reference document is read (step S34 → S32). This process is repeated until the color roller white data D33 and the reference original white data D44 fall within the range of the error to determine the final adjustment setting value DAC2 for the second surface, and this is set to EE.
It is stored in the PROM 40 (step S35).

Next, a second embodiment will be described with reference to FIG. In the first embodiment, the data D of the second surface
44 is compared with the white data D33 of the color roller 17, but in the second embodiment, it is configured to be compared with the white data D22 of the reference white plate 17a. That is, the first
In the same manner as in the embodiment, in steps S21 to S29, the adjustment set value DAC1 for the first surface is determined, and this is set to the EEPR.
When stored in the OM 40, the white data D3 of the color roller 17
It is determined whether or not the reference document has reached the second-side reading position C without reading 3 (step S31). The data is read via the converter (step S32).

Thereafter, it is determined whether or not the reference white data D11 and the reference original white data D44 are within the error range (step S33a). If not, the reference voltage (D / D) of the A / D converter is determined. The adjustment data DAC2) for the A converter is changed to change the white data D4 of the second surface of the reference original.
4 is read (step S34 → S32). Then, this processing is performed by comparing the reference white data D11 and the reference original white data D44.
Is repeated until the error falls within the range of the error, the final adjustment setting value DAC2 of the second surface is determined, and this is set in the EEPROM 40.
(Step S35).

Next, a third embodiment will be described with reference to FIG. In the second embodiment, the data D of the second surface
44 is configured to be substantially the same as the white data D22 of the reference white plate 17a, but in the third embodiment, the density difference between the white data D22 of the reference white plate 17a and the first and second surfaces is set. It is configured. That is, similarly to the second embodiment, the adjustment setting value DAC1 for the first surface is determined in steps S21 to S29, and then the reference document is moved to the second surface reading position C without reading the white data D33 of the color roller 17. It is determined whether or not it has arrived (step S31), and when it has arrived, the white data D44 of the second surface of the reference document is read via the contact image sensor 15 and its A / D converter (step S32).

Next, (reference white data D11-first, second
It is determined whether or not the density difference of the surface and the reference original white data D44 are within an error range (step S33b). If not, the reference voltage of the A / D converter (D / A)
The adjustment data DAC2 for the converter is changed to read the white data D44 of the second surface of the reference document (step S3).
4 → S32). This processing is referred to as (reference white data D1).
1-Density difference between first and second surfaces) and reference original white data D44
Is repeated until the error falls within the range of the error, the final adjustment setting value DAC2 of the second surface is determined, and this is set in the EEPROM 40.
(Step S35).

[0033]

As described above, according to the first aspect of the present invention, the first and second surfaces of the original being transported, the reference white for the first surface, and the reference white for the second surface are set. Since the reading is performed and the adjustment values for shading correction for the first surface and the second surface are determined, the operation can be simplified.

According to the second aspect of the present invention, the first and second surfaces of the original being conveyed and the reference white common to the first and second surfaces are read, and the first and second surfaces are read. The adjustment value for shading correction is determined, so that the operation can be simplified.

According to the third aspect of the present invention, the first and second surfaces of the original being conveyed are read and the reference white common to the first and second surfaces is read to read the first and second surfaces. Since the adjustment value for shading correction is determined, the operation can be simplified.

According to the fourth aspect of the present invention, since the nonvolatile memory for storing the determined shading correction adjustment value is provided, the shading correction adjustment value is determined each time the power is turned on from off. This eliminates the need and therefore simplifies the operation.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of an image reading apparatus according to the present invention.

FIG. 2 is a block diagram showing a main part of the scanner control unit of FIG. 1;

FIG. 3 is a flowchart illustrating a process of determining an adjustment value for shading correction of the image reading apparatus of FIG. 1;

FIG. 4 is a flowchart illustrating a process of determining an adjustment value for shading correction according to a second embodiment.

FIG. 5 is a flowchart illustrating a process of determining an adjustment value for shading correction according to a third embodiment.

FIG. 6 is a configuration diagram showing an image reading device according to the present invention.

FIG. 7 is a configuration diagram illustrating a main part of the ADF of FIG. 6;

FIG. 8 is a flowchart illustrating a conventional process for determining an adjustment value for shading correction.

[Explanation of symbols]

 6 CCD 15 Contact image sensor 17a White reference plate 17 Color roller 21 SCU (scanner control unit) 37 CPU 40 EEPROM 100 ADF

Claims (4)

[Claims] An image reading apparatus for optically reading a document conveyed by a document conveying means, comprising: a first surface of a document conveyed by the document conveying means;
A first reading unit for reading a reference white for a surface, a second surface of a document conveyed by the document conveying unit, and a second reading unit.
Second reading means for reading the reference white for the surface, and first reading means for reading the original read by the first reading means.
An adjustment value for shading correction for the first surface of the document is determined so that the density of the reference white for the first surface and the reference white for the first surface are substantially the same,
The second of the original read by the second reading means
Control means for determining an adjustment value for shading correction for the second side of the document such that the density of the reference white for the side and the reference white for the second side are the same. 2. An image reading apparatus for optically reading a document conveyed by a document conveying means, comprising:
A first reading unit that reads a reference white common to the first and second surfaces; a second reading unit that reads a second surface of the original conveyed by the original conveying unit; Manuscript 1
An adjustment value for shading correction for the first surface of the document is determined such that the density of the reference white common to the surface is substantially the same, and the second surface of the document read by the second reading unit and the second surface are adjusted. A control means for determining an adjustment value for shading correction for the second surface of the document so that the density of the common reference white read by the first reading means is substantially the same. 3. An image reading apparatus for optically reading a document conveyed by a document conveying means, wherein the first surface of the document conveyed by the document conveying means and the first surface
A first reading unit that reads a reference white common to the first and second surfaces, a second reading unit that reads a second surface of the document conveyed by the document conveyance unit, and a first reading unit that reads the first surface. Manuscript 1
An adjustment value for shading correction for the first surface of the document is determined such that the density of the reference white common to the surface is substantially the same, and the second surface of the document read by the second reading unit and the second surface are adjusted. A control unit for determining an adjustment value for shading correction for the second surface of the document such that the common reference white read by the first reading unit has a predetermined density difference. 4. The image reading apparatus according to claim 1, further comprising a nonvolatile memory for storing an adjustment value for shading correction determined by said control means.