JP2002344709A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader that conducts correct shading correction, even when a reference white member for shading correction in double-side original reading, becomes contaminated. SOLUTION: A reference white sheet 202 is wound on a roller 201, the part read by a contact image sensor 20 is supported by a guide section, comprising a guide plate 203 and support rollers 204, 205. When a defect of the white sheet 202 is detected in a winding roller 206, the sheet 202 is turned by a prescribed amount L so as to update the reference white sheet 202 read by the contact image sensor 20.

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, and more particularly, to an image reading apparatus capable of performing correct shading correction even when a reference white member for shading correction becomes dirty when reading both sides of a document. Related to the device.

[0002]

2. Description of the Related Art Conventionally, an image reading apparatus having a double-sided simultaneous reading mechanism as shown in FIG. 6 has been proposed. FIG. 6 is a schematic explanatory view of such an image reading apparatus, and mainly shows a layout of reading positions of both sides of a document and a transport path. The image reading device having such a configuration has a front surface (first
And a second reading sensor (contact image sensor 302) for reading the back surface (second surface), and discharges a document placed on a document tray (not shown). The first and second reading sensors 301 and 302 read both sides in one transfer while the original is being sent to the side.

Also, when reading an original, the original is illuminated by a light source and the original image is read by a sensor. Therefore, errors occur due to uneven light quantity of the light source and uneven sensitivity of the sensor. Shading correction is performed to correct this error. When performing the shading correction, a member serving as a white reference is used. In the apparatus for reading a two-sided original as described above, the reference white plate 303 is used as a white member for shading correction in the CCD, and the white plate 304 is provided in the contact image sensor so as to face the second reading sensor. And is used as a white member at the time of shading correction. Shading correction is performed by these white members.

[0004]

However, in the above-described mechanism for performing double-sided reading by paper transport, the white member serving as a shading correction reference in the contact image sensor is located at a position facing the sensor, and the original is not white. The white member may be contaminated by being conveyed between the plates, so that the back surface image of the reading surface comes into contact with the white member. If the white member becomes dirty, correct shading correction cannot be performed, and a normal read image cannot be obtained.

An object of the present invention is to solve such a problem, and an object of the present invention is to perform correct shading even when a reference white plate for shading becomes dirty during double-sided document reading.

The present invention has been made in view of such a problem, and an object of the present invention is to perform correct shading correction even when a reference white member for shading correction becomes dirty when reading a double-sided original. It is an object of the present invention to provide an image reading apparatus capable of performing the above.

[0007]

According to the present invention, in order to achieve the above object, according to the first aspect of the present invention, a document placed stationary on a platen glass is moved in the sub-scanning direction. A document reading means for reading while reading, a document conveying means for reading an image with a stationary image reading means while moving the document, and at least one reading means,
A reference white member that performs shading correction at a position facing the fixed reading unit, and an abnormality detection unit that detects an abnormality of the reference white member reading value at the time of shading correction in the fixed reading unit. The image reading apparatus further includes an updating mechanism for updating the reference white member at the time of the shading correction when an abnormality is detected by the reading unit fixed by the abnormality detecting unit.

[0008] The invention described in claim 2 is the first invention.
In the invention described in (1), the reference white member is a white sheet.

[0009] The invention described in claim 3 is the first invention.
Or the updating mechanism is a mechanism for winding up the white sheet.

According to the present invention, by adopting such a configuration, even when the reference white plate for shading correction becomes dirty during double-sided document reading, correct shading correction is automatically performed by updating the shading reference white plate. It is possible to do.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view for explaining an embodiment of an image reading apparatus according to the present invention. The image reading apparatus comprises an original feeding apparatus 1 and an original reading apparatus 19, and serves as a first reading section. The second reading unit is configured to read the information while relatively moving the unit 13 and the document 3, and to read information on the document while relatively moving the contact image sensor unit 20 and the document 3 as a second reading unit. . The contact type image sensor unit 20 includes an LED (light source), a lens, and a contact image sensor (not shown).

A document 3 is set on a document tray 2. The document feed roller 4 is paired with the separation pad 5 and feeds the documents 3 one by one. The fed document 3 is further fed into the apparatus by the intermediate roller pair 6, passed to the conveyance by the large roller 8 and the first driven roller 9, and conveyed by the second driven roller 10 around the large roller 8. Is Large roller 8 and second
The original conveyed by the driven roller 10 passes between the original scanning glass 12 and the original guide plate 17 and passes through the jump table 18.
Is again conveyed by the large roller 8 and the third driven roller 11. The document 3 is conveyed between the document glass 12 and the document guide plate 17 by the member of the document guide plate 17 in contact with the document glass 12.

Before the document 3 is conveyed, shading is performed by the first and second reading units. The first reading unit reads the reference white plate 22, and the second reading unit reads the white sheet 202 in the reference white member updating unit 21, thereby obtaining an appropriate white level.

When the original 3 passes over the original glass 12, the exposure unit 13 causes the original glass 12.
The surface in contact with is exposed. The exposing unit 13 transmits to the mirror unit 14 document image information reflected from the document 3 by exposing. The transmitted original image information is
The light is condensed by passing through the lens 15 and converted into an electric signal by the CCD sensor unit 16. The first side (front side) of the document 3 is read in the above process.

Next, the original conveyed by the large roller 8 and the third driven roller 11 is conveyed in the direction of the original discharge roller pair 7 by the close contact type image sensor unit 20 so that the second side of the original 3 ( Back side), and then ejected out of the apparatus.

FIG. 2 is a block diagram of the main functions of the image control system of the image reading apparatus. The CCD sensor unit 16 sequentially converts light information into an analog image signal 107 according to a timing signal 105 generated by a timing generation function built in the image processing unit 102, and outputs the analog image signal 107.
The A / D converter 101 converts the analog image signal 107 output from the CCD sensor unit 16 into a digital image signal 108 in accordance with the timing signal 106 from the image processor 102. The digital image signal 108 is input to the image processing unit 102, where processing such as shading correction is performed. The image processing unit 102 includes a memory I / F 11
0, image information is written to and read from the image memory unit 103.

The CPU 104 controls the entire document reading device 19. The CPU 104 sets and controls the image processing unit 102 via the CPU bus 109 and reads and writes image information. The take-up roller driving of a white sheet described later is also performed by the instruction of the CPU 104. Further, a reading mode setting and a reading operation start instruction are performed by the operation unit 110, and an abnormality detection result is displayed on the display unit 111.

FIG. 3 is a diagram showing a renewal portion of a reference white member (white sheet) for shading correction. A reference white sheet 202 is wound around a roller 201 around a roller.
In the portion read by the sensor, the guide plate 203,
It is supported by a guide section constituted by support rollers 204 and 205. When an abnormality of the white sheet is detected by the take-up roller 206, the reference white sheet read by the close contact image sensor unit 20 is updated by rotating the white sheet by a predetermined amount L. That is, a mechanism for updating the reference white member (white sheet) at the time of shading correction when an abnormality is detected in the fixed reading unit is provided.

FIGS. 4 and 5 are flowcharts for explaining the update operation of the image reading apparatus of the present invention.
The CIS in the figure is a contact image sensor (Contact Image sensor).
Sensor). First, a single-sided or double-sided reading mode is set before the reading operation starts (S10).
1). When a document is set and a reading start instruction is given (S102, S103), the first reading unit C
Perform the CD and CIS shading operation (S10
4). Next, the image reading mode is checked (S10).
5) If the reading mode is the single-sided reading mode, the process proceeds to S107; if the reading mode is the double-sided reading mode, the process proceeds to S106.

In the single-sided reading mode, the image reading apparatus 102 first transports the originals 3 one by one by the original feeding apparatus 1 and reads image information by the CCD (S10).
8). One original is read, and if the transport of the original on the original tray has not been completed, the next original is transported and read (S109). When all the originals on the original tray have been read, the one-sided reading mode is terminated and the operation shifts to a normal standby state.

In the double-side reading mode, the originals 3 are conveyed one by one by the original feeder 1, and the front side of the original is read by the CCD (S113). When the original is transported and reaches the CIS position, the reading of the back side of the original is
Performed by IS (S114). The front and back sides of one document are read, and if the conveyance of the document on the document tray has not been completed, the conveyance and reading of the next document are performed (S
115). When all the originals on the original tray have been read, the abnormality of the white sheet facing the CIS is detected (S1).
16). Here, it is determined whether there is an abnormality in the white sheet (S117). If no abnormality is found, the duplex reading mode is terminated and the operation shifts to a normal standby state. When an abnormality is found, the white sheet updating unit 2
1, the white sheet 202 is updated, and the state shifts to the standby state.

In this embodiment, the abnormality detection and the update of the reference white member are performed after a series of reading jobs. However, the detection may be performed every time one document is read or before the reading job is started. In the present embodiment, the CCD and the CIS are used. However, a configuration in which both the CISs are used may be such that an automatic updating unit of a white member is installed at a position facing each CIS.

As described above, according to this embodiment, after double-sided reading, an abnormality such as dirt on a white sheet is detected,
When an abnormality is detected, the updating unit updates the white sheet, so that correct shading correction can be performed at the next reading.

In the above-described embodiment, the case where the continuous white sheet is wound has been described. However, the white sheet may be attached at a predetermined interval, and the updating mechanism moves on a plane. It may be a mechanism.

[0025]

As described above, according to the present invention, when an abnormality is detected by the reading means fixed by the abnormality detecting means, the updating mechanism for updating the reference white member at the time of shading correction is provided. Even when the white member for shading correction becomes dirty during double-sided document reading, correct shading correction can be performed by updating the shading reference white member.

In addition, since the reference white member is a white sheet and the white sheet is wound up, when an abnormality is detected in the white sheet, the reference white member is moved (rotated) by a predetermined amount to thereby make the reference sheet white. The white sheet can be updated.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an embodiment of an image reading apparatus of the present invention.

FIG. 2 is a block diagram of main functions of an image control system of the image reading device.

FIG. 3 is a diagram showing an updating unit of a reference white member in the embodiment shown in FIG.

FIG. 4 is a flowchart (part 1) for explaining an update operation of the image reading apparatus of the present invention.

FIG. 5 is a flowchart (part 2) for explaining an update operation of the image reading apparatus of the present invention.

FIG. 6 is a diagram illustrating an image reading apparatus having a conventional double-sided reading mechanism.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 document feeder 2 document tray 3 document 4 document feed roller 5 separation pad 6 intermediate roller pair 7 document discharge roller pair 8 large roller 9 first driven roller 10 second driven roller 11 third driven roller 12 Glass 13 Exposure unit 14 Mirror unit 15 Lens 16 CCD sensor unit 17 Document guide plate 18 Jump table 19 Document reading device 20 Contact image sensor unit 21 Reference white member updating unit 101 A / D conversion unit 102 Image processing unit 103 Image memory unit 104 CPU 105 Timing signal 106 Timing signal 107 Analog image signal 108 Digital image signal 109 CPU bus 110 Memory I / F 111 Display unit 112 Sensor input unit 113 Motor drive unit 201 Roller 202 Reference white sheet 203 Guide plate 204 205 supporting rollers 206 take-up roller 301 first reading sensor (CCD) 302 second reading sensor (contact image sensor) 303 and 304 reference white plate

Claims (3)

[Claims] 1. A document reading means for reading an original stationarily placed on a platen glass while moving in the sub-scanning direction, and a document conveying means for reading an image by a stationary image reading means while moving the document. , At least one reading unit is fixed, and a reference white member for performing shading correction is provided at a position facing the fixed reading unit, and a reference white member reading value at the time of shading correction in the fixed reading unit. An updating mechanism for updating the reference white member at the time of the shading correction when an abnormality is detected in the reading unit fixed by the abnormality detecting unit. An image reading apparatus comprising: 2. The image reading apparatus according to claim 1, wherein the reference white member is a white sheet. 3. The image reading apparatus according to claim 1, wherein the updating mechanism is a mechanism for winding the white sheet.