JP2596327B2 - Original image reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document image reading apparatus, and more particularly to a document image reading apparatus which is used in an image information processing apparatus such as a facsimile or an image scanner and has a structure for reading image information of a document by photoelectric conversion. Things.

[0002]

2. Description of the Related Art FIGS. 5 and 6 show a schematic configuration of a conventional document image reading apparatus. FIG. 5 is a cross-sectional view of a mechanical section of a conventional apparatus, and FIG. 6 shows a configuration example of an image data input circuit using a conventional shading correction method.

[0005] In FIG. 5, reference numeral 51 denotes a document contact type reading device. This original contact type reading device 51
Has a function of reading an image of a document and performing photoelectric conversion. Reference numeral 57 denotes an automatic sheet feeding unit. The automatic paper feeder 57 includes a document separation piece 54 and a document feed roller 53, and separates and feeds the documents one by one toward the document contact type reading device 51. Further, reference numeral 52 denotes a white document conveying roller. The document conveying roller 52 presses the fed document to the reading position A of the document contact type reading device 51 and conveys the document while bringing the document into close contact therewith. It has a function of causing the contact reading device 51 to read.

The reference data for the white reference determination and the image data of the original read by the original close contact reading device 51 are subjected to a shading correction operation via an analog / digital conversion element 59 as shown in FIG. 6, for example. It is sent to the arithmetic circuit 61. Reference numeral 60 denotes a memory for storing at least one line of shading data for storing the reference data for the white reference determination.

[0005]

However, in the above conventional example, when the white reference data read by each sensor element and the shading data stored in the memory are subjected to shading correction in the arithmetic circuit,
Due to the partial deterioration of each sensor element in the original contact type reading device caused by extraneous light and the temporal deterioration of the LED which is the light source for reading the original image, the data has a large partial output decrease, and the original image information There was a problem that reading was inaccurate.

Also, in a document image reading apparatus or the like in which the white reference setting of a document is performed by a white document transport roller, the document transport roller becomes dirty due to the passage of the document, and the shading correction data of the dirty portion is output. As a result, the reading of the document image information becomes inaccurate in the same manner as described above.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to improve the disadvantages of the prior art, and in particular to make it possible to always set the same level of data for shading correction data, thereby improving the reading accuracy of original image information. It is an object of the present invention to provide a document image reading apparatus aiming at the above.

[0008]

According to the present invention, there is provided a document reading device for reading shading correction data and document information by an optical method, and a document for constantly bringing a document P sent to the document reading device into contact with the document reading device. The image processing apparatus includes a transport roller, an arithmetic circuit for performing shading correction on image information read by the document reading device, and outputting the information, and a memory for sending shading correction data to the arithmetic circuit.

An original detection sensor is provided upstream of the original transport roller. A document identification circuit that identifies whether the document P sent to the document reading device based on the output signals of the document detection sensor and the document reading device is a document for information reading or a white reference correction sheet on which correction data is mounted, It is provided in the output stage of the document reading device described above.

The document identification circuit has a correction data rewriting control function of rewriting the shading correction data in the memory based on the shading correction data read by the document reading device. This aims to achieve the above-mentioned object.

[0011]

[Operation] When the white reference correction sheet 13 is set, the document detection sensor first determines that the sheet is the white reference correction sheet 13, and the information is input to the document identification circuit 12 in FIG. Next, when the white reference correction sheet 13 is sent to the document reading device, reading of the white portion 13B of the white reference correction sheet 13 by the document reading device is started. Then, the white portion data of the white reference correction sheet 13 that has been read is rewritten with shading correction data in the memory 10. Subsequently, the white reference correction sheet 13 is discharged by the document conveying roller 2, and the rewriting of the data in the memory 10 ends.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In the embodiment shown in FIGS. 1 to 4, the original contact reading device 1 serving as an original reading device for reading shading correction data and original information by an optical method, and an original P sent to the original contact reading device 1 are used. A document conveying roller 2 which is always in contact with the document reading device 1, an arithmetic circuit 11 which performs shading correction on image information read by the original close contact reading device 1, and outputs the shading correction data to the arithmetic circuit 11. And a memory 10.

A paper guide 6 is provided on the upstream side of the document feed roller 2, and a document detection sensor 5 is provided on the paper guide 6. A document feed roller 3 and a document separation piece 4 are provided between the document detection sensor 5 and the above-mentioned document contact type reading device 1.

Further, based on the output signals of the original detecting sensor 5 and the original reading device 1, the original P sent to the original reading device 1 is either an information reading original or a white reference on which correction data is mounted. An original identification circuit 12 for identifying the correction sheet 13 (see FIG. 3) is provided at an output stage of the original close contact type reading device 1 described above.

The document identification circuit 12 has a correction data rewriting control function for rewriting the shading correction data in the memory 10 based on the shading correction data read by the document contact type reading device 1.

The white reference correction sheet 13 is a sheet whose width is equal to or greater than the maximum effective reading width of the original close contact type reading device 1 and whose length is equal to or greater than the length capable of conveying the original.
B (constant color) has a length of at least 1 mm and exists in the entire width in the reading width direction of the original contact type reading device 1, and an identification hole 13A for identifying the white reference correction sheet 13 from another sheet. Is provided.

The white reference correction sheet 13 has a white band 13B having a predetermined width in a direction perpendicular to the sheet conveyance direction. The white band 13B of the white reference correction sheet 13 is coated with a transparent resin, which has the advantage that the white portion 13B of the white reference correction sheet 13 is resistant to dirt and prevents deterioration of the sheet material.

More specifically, the original contact reading device 1 has a function of reading an image of the original P and performing photoelectric conversion. Reference numeral 7 denotes an automatic paper feeding unit, which is composed of a document separating piece 4 and a document feeding roller 3 and has a function of separating and feeding the documents P one by one toward the document contact type reading device 1. I have.

The document transport roller 2 has a document transport function of transporting the document P by pressing the document P fed as described above to the reading position A of the document contact type reading device 1 and bringing the document P into close contact therewith. .

FIG. 2 is a block diagram showing the relationship between the original reading device 1 and an arithmetic circuit 11 for performing shading correction of data read by the original reading device 1.

In FIG. 2, the document identification circuit 12
It is determined whether the original image data read by the original close contact reading device 1 is data of a general original or white data of a white reference correction sheet 13 (see FIG. 3). A / D conversion element)
9, and in the case of white data of the white reference correction sheet 13, functions to input to the memory 10.
The memory 10 can store at least one line of shading data. As described above, the arithmetic circuit 11 has a function of performing a shading correction operation on document image data read by the document-contact reading device 1.

Next, the operation of this embodiment will be described.

When the white reference correction sheet 13 shown in FIG. 3 is set in the apparatus, as shown in FIG.
, The leading end of the white reference correction sheet 13 is detected, and while being conveyed by the document feed roller 3 to the reading position A of the original contact type reading device 1, the white reference correction sheet 13
Is provided so as to pass over the head of the document detection sensor 5, and the moment the discrimination hole 13 A passes through the document detection sensor 5, the document detection sensor 5
As shown in (B), the state is once undetected. Then, when the identification holes 13A of the white reference correction sheet 13 have passed, the document detection sensor 5 is in the detection state again as shown in FIG.

This information is input to the document identification circuit 12 shown in FIG. 2, and it is determined that the sheet is the white reference correction sheet 13 set in the apparatus, and the shading data in the memory 10 shown in FIG. The reference correction sheet 13 is automatically conveyed. The timing of conveyance from the end position of the identification hole 13A in the white reference correction sheet 13 to the white portion 13B is controlled in a software manner by a step angle of a stepping motor that drives the document conveyance roller 2. When the white portion 13B of the white reference correction sheet 13 reaches the reading position A of the original close contact reading device 1, reading of the white portion 13B of the white reference correction sheet 13 is started.

Then, the read white reference correction sheet 13 is read.
Is rewritten with shading correction data in the memory 10. The white reference correction sheet 13 is discharged by the document conveying roller 2, and the rewriting of the data in the memory 10 ends.

[0026]

Since the present invention is constructed and functions as described above, according to this, the white reference correction sheet is set in the apparatus in the same manner as a general original, and is read by the original close contact type reading device, so that the memory in the memory is read. Rewriting the shading data of the original, and preventing a partial decrease in the output of the shading correction data due to deterioration of the sensor or the LED, thereby enabling accurate reading of the original image information. An apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram showing an example for executing shading correction on information read by a document contact type reading device in FIG. 1;

FIG. 3 is an explanatory diagram illustrating an example of a white reference correction sheet used in FIG. 1;

FIG. 4A is an explanatory diagram showing the operation of FIG. 1, and FIG. 4A shows a state immediately after a white reference correction sheet is input;
FIG. 6B shows a state in which a white reference correction sheet is detected .
FIG . 4C shows a state immediately after the white reference correction sheet is separated from the detection sensor.

FIG. 5 is a schematic configuration diagram showing a conventional example.

FIG. 6 is a block diagram showing an example for performing shading correction in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Original contact type reading device as original reading device 2 Original conveyance roller (white) 3 Original feed roller 10 Memory 11 Operation circuit 12 Original identification circuit 13 White reference correction sheet

Claims (3)

(57) [Claims] 1. A document reading device for reading shading correction data and document information by an optical method, a document feed roller for constantly bringing a document fed into the document reading device into contact with the document reading device, and a document reading device. In a document image reading apparatus having a calculation circuit for performing shading correction on read image information and outputting the same, and a memory for sending shading correction data to the calculation circuit, a document detection sensor is provided upstream of the document conveyance roller. A document identification circuit for identifying, based on the output signals of the document detection sensor and the document reading device, whether the document sent to the document reading device is an information reading document or a white reference correction sheet on which correction data is mounted; Is provided in the output stage of the document reading device, Document identification circuit, the document reading based on the shading correction data read by the device rewrites shading correction data in the memory the correction data rewrite control function original image reading apparatus characterized by comprising a. 2. The original image reading apparatus according to claim 1, wherein the white reference correction sheet includes a white band having a predetermined width in a direction orthogonal to a sheet conveying direction. 3. A white band portion of the white reference correction sheet,
3. A transparent resin coating.
Document reading device according to the above.