JP2018152698A - Document reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which, when calculating shading data by a document, in the case where shading data generation is executed with a document unsuitable as a white reference such as a thin sheet, since normal shading data cannot be acquired, uneven images may be output.SOLUTION: When generating shading data, and when a document such as thin paper is detected, in the case of a thin paper document, by performing a double feed transfer and acquiring the shading data, it becomes possible to perform accurate shading correction irrespective of a type of document to be used.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a technique of a document reading apparatus that reads image information recorded on a document.

  In a document reading apparatus that reads an image of a document by a reading unit composed of an imaging element such as a CCD, in order to correct reading unevenness due to variations in characteristics of an optical system, a light emitting element, and an imaging element included in the reading unit, Shading correction is performed by reading a white reference document or white reference plate.

  Also, in a document reading device used in a copying machine or the like, a document is transported one page at a time on a platen glass by a document transport device, and is exposed by an exposure device fixed on the transport path to read a document image. What performs so-called “flow-reading” is known.

  With respect to the shading correction method of the document reading apparatus that performs such a flow reading, Japanese Patent Application Laid-Open No. 2004-133867 describes a technique for reading a document in a document transport path and obtaining a correction value for shading correction.

JP 2004-207790 A

  However, in the above-mentioned prior art, in Patent Document 1, when the shading data generation is performed by a blank sheet at hand of the user, for example, when the original has a non-uniform density of the blank sheet, the acquisition is performed. There is a possibility that normal shading data cannot be acquired because the image data that can be obtained is non-uniform. A thin paper or the like can be considered as a document having a non-uniform density.

  If shading data generation is performed on a document that is not suitable as a white reference, such as thin paper, uneven shading data may be output because the shading data is not normal.

  In order to solve this problem, the present invention makes it possible to obtain normal shading data even if the blank paper at hand of the user is an original that tends to be uneven, such as a thin paper.

In order to solve the above-mentioned problem, in the invention according to claim 1,
An original conveying means (105) for conveying an original; an original reading means (106) for reading the conveyed original; an original stacking means for loading an original (101);
A document separating means (122) for separating and conveying the documents stacked on the document stacking means;
The document separation means (122) includes a first document separation roller (122a) that rotates and conveys at the top of the document, a second document separation roller (122b) that rotates and conveys at the bottom of the document,
A second document separation roller control unit for controlling the second document separation roller; (111); a document discrimination unit for determining the type of the document separated by the document separation unit;
Shading data generating means (401, 405) for generating a shading data by reading an original conveyed from the original conveying section (105) by the original reading section (106), and shading data generated by the shading data generating means. In a document reading apparatus having a holding means (402) for holding
When reading the document conveyed from the document conveying unit (105) and generating the shading data, the document separation control unit causes the document separation control unit to separate and feed the document according to the document determined by the document determination unit. It is characterized by being conveyed.

  In the present invention, an accurate shading correction is performed on a document used when generating shading data, regardless of the type of document used.

  It is possible to obtain normal shading data even if a blank paper at hand of the user is an original that tends to be non-uniform, such as a thin paper.

1 is a configuration diagram of a document reading device. It is a control block diagram of a document reading apparatus. FIG. 6 is an operation explanatory diagram of a document separation unit. The control flowchart at the time of shading data acquisition is shown.

  Hereinafter, embodiments of the present invention will be described in detail.

[Example 1]
FIG. 1 shows a configuration of a document reading device 120 equipped with an automatic document transport mechanism. In FIG. 1, reference numeral 101 denotes a document tray on which documents 102 are stacked. Further, a document pick roller 121, document separation rollers 122a and 122b, a document transport roller 123, and a document discharge roller 124 are driven by a document transport motor (not shown). An image of the original 102 by the original reading unit 106 that feeds the original 102 placed on the original tray 101 and reads the image information of the original 102 passing through the original reading position of the original reading unit 106 by the original reading unit 106. When the reading is completed, the document 102 is discharged to the discharge tray 108.

  The document reading unit 106 includes LED light sources 201 and 202 that irradiate light to the document surface at the document reading position. The CIS line sensor 203 photoelectrically converts the reflected light from the document 102 guided by the lens 204 with a light receiving element, and outputs an electrical signal corresponding to the amount of incident light.

  The original 102 is read at the original reading position while the original 102 is conveyed by the original reading apparatus having the above-described configuration.

FIG. 2 is a diagram showing a control configuration of the document reading apparatus according to the embodiment of the present invention. The CPU 401 is a main CPU for controlling the document reading apparatus, and controls the LED light sources 201 and 202, the CIS line sensor 203, the document transport motor 105, the separation roller solenoid 111, and the backup RAM 402 to read the document image. The CPU 401 is connected to the document thickness detection sensor 112 and can detect the thickness of the document. (The thickness detection method will be described later)
Next, the flow of the image signal will be described. An electrical signal corresponding to the density of the original read by the CIS line sensor 203 is converted from an analog electrical signal to a digital image signal by the A / D conversion circuit 403. Next, the shading correction circuit 404 corrects the influence of the non-uniformity of the light amounts of the LED light sources 201 and 202 and the influence of the pixel sensitivity of the CIS line sensor 203, and the image signal corrected by the shading correction circuit 404 is output.

  The backup RAM 402 is a non-volatile RAM for storing a white reference original reading value (hereinafter referred to as shading data) for shading correction. The backup RAM 402 reads / writes from the CPU 401 and the shading correction circuit 404 via the CPU 401. It is configured to be able to send and receive data between.

  The temporary calculation RAM 405 is a RAM used by the CPU 401 when temporarily storing data from the backup RAM 402 and the shading correction circuit 404, and is configured to be able to transmit and receive data under the control of the CPU. Yes.

Next, details of the shading correction performed by the shading correction circuit 404 will be described.
In the shading correction, the following calculation is performed in order to correct the influence of the non-uniformity of the light amount of the LED light sources 201 and 202 and the influence of the sensitivity variation for each pixel of the CIS line sensor 203.
Shading correction output (n) = document read value (n) / shading data (n) × read target value * n = indicates CIS line sensor 203 pixel position * read target value = read value when reading a white reference document Set the target value.
* Shading data = Data obtained when a white reference document is scanned.

  The shading correction is performed by storing the data when the shading data is acquired in the backup RAM 402 and setting the data from the backup RAM 402 to the shading correction circuit 404 from the CPU 401 when reading the document.

  By performing the above calculation, it is possible to perform reading while correcting the influence of the non-uniformity of the light amount of the LED light sources 201 and 202 and the influence of the sensitivity variation for each pixel of the CIS line sensor 203.

  In addition, the shading correction circuit 404 has a through transfer mode in which the original read data is transferred without correction to the CPU 401 without performing shading correction in accordance with an instruction from the CPU 401. In the shading data acquisition mode described later, the operation is performed in the through transfer mode.

Next, document conveyance when using a document and calculating shading data will be described with reference to FIG. FIG. 3A is a diagram showing the original document conveyance at the normal time.
During normal conveyance, the document pick motor 121 and the document separation roller 122a are driven by the document conveyance motor 105. The document 102 stacked on the document stacking tray 101 is conveyed by the document pick roller 121 toward the document separation roller 122a. The conveyed document is conveyed downstream by the document separation roller 122a. At this time, the document separation roller 122b is in a fixed state without the separation roller solenoid 111 being OFF and the document separation roller 122b is not rotated. Therefore, the bundled originals 102 can be separated and the originals can be conveyed one by one.

At this time, the conveyed document detects the thickness of the document at the position of the document thickness detection sensor 112. Document thickness detection sensor 112 includes a transmissive optical sensor (not shown).
The document thickness detection sensor is a transmissive optical sensor. The CPU 401 detects the light transmittance of the document, that is, the ratio of the amount of light reaching the other surface to the amount of light irradiated from one surface. Detect the thickness of the document. If the detected thickness is equal to or greater than a certain amount (that is, not thin paper), the separated original is conveyed as it is, and shading data is acquired at the original reading position.

FIG. 3B is a diagram illustrating the conveyance of a multi-fed original when thin paper is used. The document transport motor 105 drives the document pick roller 121 and the document separation roller 122a. The document 102 stacked on the document stacking tray 101 is conveyed by the document pick roller 121 toward the document separation roller 122a. The conveyed document is conveyed downstream by the document separation roller 122a. At this time, the document separation roller 122b is in a fixed state without the separation roller solenoid 111 being OFF and the document separation roller 122b is not rotated.
Therefore, the bundled originals 102 can be separated and the originals can be conveyed one by one.

  At this time, the conveyed document detects the thickness of the document at the position of the document thickness detection sensor 112. As described above, in the document thickness detection sensor 112, the CPU 401 detects and determines the thickness of the document based on the transmittance of the transmissive optical sensor. When the detected thickness is equal to or less than a certain thickness (thin paper or the like), the separation roller solenoid 111 is turned on to rotate the document separation roller 122b. The document separation rollers 122a and 122b both transport the document in a double feed state without separating the document bundle so that the document is transported, and obtain shading data at the document reading position.

Next, the operation at the time of obtaining shading data, which is a feature of the present invention, will be described with reference to the flowchart of FIG.

  The CPU 401 detects a document reading start signal (S601), and when a shading data acquisition start instruction is detected (S602), the CPU 401 determines whether to calculate shading data (S603). When the shading data is calculated (S603), the document transport motor 105 is driven to start transporting the document 102 placed on the document tray 101 (S604).

Next, the LED light sources 201 and 202 and the CIS line sensor 203 are driven, and the shading correction circuit 404 is set to the through transfer mode to start reading a document. (S605)
As a result of the document thickness detection sensor 112, when the CPU 401 determines that the document thickness is equal to or larger than a certain amount (S606), shading data based on the document is calculated (S608).

  As a result of the document thickness detection sensor 112, if the CPU 401 determines that the document thickness is not equal to or greater than a certain amount (S606), if the document is thin paper, the separation roller solenoid 111 is driven and both the separation rollers 122a and 122b are driven. The original is conveyed in a double feed state without separation (S607). When the document is conveyed and detected again by the document thickness detection sensor 112 and the CPU 401 determines that the document thickness is equal to or greater than a certain amount (S606), shading data from the document is calculated (S608).

  When the shading data acquisition start instruction is detected (S602) and the CPU 401 does not calculate shading data (S603), the separation roller solenoid 111 is not driven and only the separation roller 122a is driven to separate the documents one by one. Carrying is performed (S609).

  A normal reading operation is performed (S610), and the reading operation is performed until there is no document (S611). When there is no document, the operation is terminated.

As a result, in the case of a document such as thin paper as a document to be used when generating shading data, it is possible to perform accurate shading correction independent of the type of document to be used by performing multi-feed conveyance and acquiring shading data.

101 Document tray 102 Document 105 Document transport motor 106 Document reading unit 107 Document reading position 108 Paper discharge tray 111 Separation roller solenoid 112 Document thickness detection sensor 121 Document pick roller 122a Document separation roller 122b Document separation roller 123 Document transport roller 124 Document ejection Roller 201 LED light source 202 LED light source 203 CIS line sensor 204 Mirror 401 CPU
402 Backup RAM
403 A / D conversion circuit 404 Shading correction circuit 405 Temporary SRAM for calculation

Claims (1)

An original conveying means (105) for conveying an original; an original reading means (106) for reading the conveyed original; an original stacking means for loading an original (101);
A document separating means (122) for separating and conveying the documents stacked on the document stacking means;
The document separation means (122) includes a first document separation roller (122a) that rotates and conveys at the top of the document, a second document separation roller (122b) that rotates and conveys at the bottom of the document,
A second document separation roller control unit for controlling the second document separation roller; (111); a document discrimination unit for determining the type of the document separated by the document separation unit;
Shading data generating means (401, 405) for generating a shading data by reading an original conveyed from the original conveying section (105) by the original reading section (106), and shading data generated by the shading data generating means. In a document reading apparatus having a holding means (402) for holding
When reading the document conveyed from the document conveying unit (105) and generating the shading data, the document separation control unit causes the document separation control unit to separate and feed the document according to the document determined by the document determination unit. A document reading device characterized by being conveyed.