JPH10136167A - Image reading device - Google Patents

Abstract

(57) [Problem] To provide an image reading device capable of performing shading correction without passing white paper or directly pressing a white jig against a sensor. A shading correction is carried out with a separation portion (4a) supported by a shaft (3a) of a reading roller (3) that conveys a document while pressing the document against the image sensor (1). And a support means 4 having a shading member 5 for moving the shading member 5 to a reading position C of the image sensor 1 by rotating the shaft 3a in a predetermined direction to perform shading correction. apparatus.

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 used for a facsimile apparatus, a copying machine, etc., and more particularly to an image reading apparatus used for a facsimile apparatus.

[0002]

2. Description of the Related Art As an image reading apparatus, an image reading apparatus using a contact image sensor is known. 2. Description of the Related Art Image reading apparatuses using a contact-type image sensor have become popular because they can be easily miniaturized. With this type of image reading device, image sensitivity such as black streaks that occur when the reading accuracy of the sensor changes due to differences in the sensitivity of the sensor and deterioration with time or movement of dust or the like in the optical path of the sensor. Is corrected using a white reference.

Further, in this type of image reading apparatus, a reading roller for pressing the original against the sensor when reading the image information of the original is provided at a portion facing the sensor.
Normally, a white roller is used as the reading roller in order to improve the reading sensitivity of the sensor.

Accordingly, it is conceivable to perform shading correction using the white reading roller. However, the reading roller becomes dirty during the passage of the document, and cannot be used as a white reference for performing shading correction. .

Therefore, shading correction is performed by passing white paper or pressing a white jig directly against the sensor. The restoration of image quality by shading correction is to cope with image degradation such as black stripes that occur when the reading sensitivity of the sensor changes due to deterioration over time or movement of dust etc. in the optical path of the sensor. Therefore, the shading correction needs to be performed frequently to maintain the image quality.

[0006]

However, in shading correction using a method of passing white paper or pressing a white jig directly against a sensor, there is a problem in workability or the like to frequently perform this. is there.

The present invention solves the above problems and provides an image reading apparatus capable of performing shading correction without passing white paper or pressing a white jig directly against a sensor. is there.

[0008]

According to the first aspect of the present invention,
In an image reading apparatus including a contact image sensor that reads image information of a document and a reading roller that conveys the document while pressing the document against the image sensor by rotating in one direction, the image reading device is rotatably supported by a shaft of the reading roller. A support means for supporting a base end of a shading member made of a white sheet for performing shading correction, and a clutch for rotating the support means by a predetermined amount with respect to the reading roller by rotation of the reading roller; The shading correction is performed by moving the shading member to the reading position of the image sensor by rotating the roller in the other direction.

According to a second aspect of the present invention, in the image reading apparatus of the first aspect, the shading member has a cleaning unit for cleaning the image sensor.

According to a third aspect of the present invention, in the image reading apparatus according to the second aspect, the cleaning section is provided at an end of the shading member opposite to the base end.

According to a fourth aspect of the present invention, in the image reading apparatus according to the first, second or third aspect, the shading member has a separation portion for separating the reading roller and the image sensor during shading correction. It is characterized by the following.

[0012]

FIG. 1 shows a schematic side view of a facsimile apparatus to which an image reading apparatus according to an embodiment of the present invention is applied. A document table 16 having a document width guide 16a for positioning the document 2 in the width direction is provided at an upper portion of the apparatus main body 17. The document width guide 16 is slidable in the width direction of the document 2 (vertical direction in FIG. 1) according to the width of the document 2. The document 2 is positioned in the width direction by the document width guide 16 and the upper guide plate 1 is positioned from the right in FIG.
3 and is inserted between the lower guide plate 14 and placed.

When reading a plurality of originals, the originals are separated one by one by the separation roller 8 at a separation section, which is constituted by a separation roller 8, an auxiliary leaf spring 12 and a separation rubber 10, and is located at the leading end of the bundle of originals. And feed. Separation rubber 10
Is pressed against the separation roller 8 by a separation pressure bracket 9 pressed by a tension spring 11.

The separated original is contacted by a feed roller 6 and a tension roller 7 pressed against the feed roller 6 at a predetermined conveying speed at a contact type image sensor 1 shown in FIG. The sheet is conveyed to an image reading device including the reading roller 3 and the like. The contact type image sensor 1
The pressing plate spring 15 presses the reading roller 3 against the reading roller 3. The image information of the document 2 is read while the document 2 conveyed to the image reading device is pressed against the close contact type image sensor 1 by the reading roller 3 rotating in the direction A as shown in FIG.

As shown in FIGS. 2 and 3, the image reading apparatus includes a contact-type image sensor (hereinafter, referred to as a sensor) 1 for reading image information of a document 2 and a reading device for conveying the document 2 while pressing the sensor 2 against the sensor 1. Roller 3 and shaft 3 of reading roller 3
a supporting means 4 for supporting the base end of a shading member 5 as a white sheet made of mylar (trade name) for performing shading correction.
Since the image reading apparatus is substantially symmetrical with respect to a plane perpendicular to the axis 3a at the axial center of the reading roller axis 3a, the description will be made only on one end side.

The sensor 1 includes a cover glass 1a which is pressed against the original 2 when reading an image, an LED array 1b as a light emitter, and light reflected from the original 2 from the LED array 1b.
That is, it has a lens array 1c for converging the reflected light as image information, and a photoelectric sensor 1d for reading the reflected light transmitted through the lens array 1c and converting it into a current.

The shading member 5 is formed of a thin plate so as to partially cover the shading member 5 with a slight gap between the shading member 5 and the peripheral surface of the reading roller 3. The free end has a cleaning unit 5a for cleaning the cover glass 1a of the image sensor 1. Cleaning unit 5a
Is constructed by attaching a non-woven cloth to the surface of the shading member 5.

The shading member 5 positioned between the reading roller 3 and the image sensor 1 is attached to the cover glass 1a during white reference reading or cleaning (see FIG. 3) for shading correction, which will be described later. A protruding portion 4a is provided as a separating portion for separating the reading roller 3 from the image sensor 1 so that the reading roller 3 and the image sensor 1 contact each other with an appropriate pressure.

FIGS. 4 and 5 show how the reading roller 3 and the support means 4 are attached to each other. The end of the shaft 3a of the reading roller 3 passes through a boss 4b of the support means 4 and a driving boss 19 driven by a driving source (not shown), and is rotatably supported by the side plate 20. The shaft 3 a is loosely fitted to the support means 4 and is fixed to the drive boss 19 by a screw 21. The side plate 20 has a bent portion 20 facing the support means 4 side.
a and 20b are provided.

A boss 4b provided at an end of the support means 4
Are opposed to a drive boss 19, and these are detachably connected to each other by a clutch 18 formed of a close-wound coil spring. The clutch 18 covers the boss 4b of the support means 4 and the drive boss 19 (see FIG. 5). The clutch 18 has bent portions 18a and 18b, which are bent in the radial direction, at the end on the drive boss 19 side and the end on the support means 4 side, respectively.

The bent portions 18a and 18b of the clutch 18 are engaged with positioning portions 4c and 4d provided at both ends of the boss portion 4b of the support means 4 so as to extend in the axial direction. The positioning portions 4c and 4d are bent portions 20a and 20
b. Since the reading roller 3 and the supporting means 4 are attached in this manner, the supporting means 4
Is a fixed amount relative to the reading roller 3, that is, the bent portion 20
It is rotatable by an amount determined by the distance between a and 20b, and always occupies a position within a certain range with respect to the sensor.

The image information of the original 2 and the shading member 5 at the time of reading the white reference, which will be described later, irradiates the surface of the original 2 with light from the LED array 1b, which is emitted under the control of a control unit (not shown). Is transmitted through the lens array 1c and converted into a current by the photoelectric sensor 1d to be read. This current is sent to the control unit and undergoes a predetermined process.

The operator places the document 2 on the document table 16,
When a switch for starting image reading is turned on by a key operation on a panel (not shown), the white color of the shading member 5 is changed to perform shading correction before image reading starts.
Read as white reference. At this time, as shown in FIGS. 3 and 7, the reading roller 3 is rotated together with the drive boss 19 in the direction B, which is opposite to the direction A.

The rotation of the drive boss 19 is transmitted to the support means 4 via the clutch 18, and the support means 4 rotates until the positioning part 4c engages with the bending part 20b. By this rotation, the separating portion 5a pushes down the sensor 1 against the pressure of the pressing leaf spring 15 (see FIG. 1), and the shading member 5 enters between the reading roller 3 and the sensor 1. The cleaning unit 5a of the shading member 5 wipes the surface of the cover glass 1a to perform cleaning, and when further rotated, the shading correction portion of the shading member 5 moves to the image reading position C (see FIG. 3).

At this time, the positioning portion 4c engages with the bending portion 20b, and the bending portion 18b receives a force from the positioning portion 4c in a direction to loosen the clutch 18, and the rotation of the drive boss 19 is transmitted to the clutch 18. The positioning portion 4c is held in a state of being engaged with the bent portion 20b of the side plate 20, and the shading of the shading member 5 is performed, even though the drive boss 19 and the reading roller 3 are both rotating in the B direction. The correction portion is held in a state where it is located at the image reading section C. The control unit causes the LED array 1b to emit light, and the reflected light from the surface of the shading member 5 passes through the lens array 1c, is converted into a current by the photoelectric sensor 1d, sent to the control unit, recorded, and corrected for shading. Is read based on the white reference.

As shown in FIG. 2, at the time of image reading, the reading roller 3 rotates in the direction A due to the rotation of the driving boss 19. The rotation of the drive boss 19 is also transmitted to the clutch 18, and the engagement between the bent portion 18b and the positioning portion 4c is released. Clutch 1 in which no force is applied to bent portion 18b
Reference numeral 8 fixes the boss 4b, and the support means 4 is rotated together with the drive boss 19 until the positioning portion 4d engages the bent portion 20a.

When the positioning portion 4d is engaged with the bending portion 20a, the bending portion 18a is moved from the positioning portion 4d to the clutch 1a.
8, the rotation of the drive boss 19 is not transmitted to the clutch 18, and the positioning portion 4d is rotated by the side plate despite the fact that the drive boss 19 and the reading roller 3 are both rotating in the A direction. 20 is held in a state of being engaged with the bent portion 20a. In this state, the image reading of the document 2 conveyed from the separation unit is started.

When the detection means (not shown) detects that the leading end of the document 2 has reached the image reading position C, a signal from the detection means is transmitted to the control unit, and the control unit receives the signal and causes the LED array 1b to emit light. . The light reflected from the surface of the document 2 passes through the lens array 1c, is converted into a current by the photoelectric sensor 1d, sent to the control unit, and performs shading correction based on the recorded white reference. The control unit outputs the data after the shading correction to a predetermined mechanism and starts fax transmission. After the image reading is completed, before the image reading is started again, a white reference reading based on the white color of the shading member for shading correction is performed.

In this embodiment, the shading correction is performed every time the next image is read after the image is read. However, the shading correction may be performed every predetermined number of times of image reading. It may be performed every time a fax is transmitted, or every predetermined time. Although a non-woven cloth is used for the cleaning portion 5a, a sponge-like material may be used, or a matte process in which the surface of the shading member 5 is slightly roughened may be performed to form the cleaning portion 5a. . The position where the cleaning portion 5a is formed is not limited to the end opposite to the base end of the shading member 5, and may be appropriately set at an appropriate position of the shading member 5.

[0030]

According to the first aspect of the present invention, the shading member can be easily moved and shading correction can be performed simply by using the clutch and changing the rotation direction of the reading roller, so that the image can be easily read. Maintain accuracy,
Good image information can be obtained, and the reliability of image reading accuracy can be maintained.

According to the second and third aspects of the present invention, the shading member is moved for shading correction, so that the cleaning section provided on the shading member automatically performs cleaning. The image reading accuracy can be maintained, good image information can be obtained, and the reliability of the image reading accuracy can be maintained.

According to the fourth aspect of the present invention, since the shading member has the separation portion for separating the reading roller and the image sensor during shading correction,
When the white mylar is moved to abut the image sensor for shading correction, neither the image sensor nor the white mylar is damaged, and the image reading accuracy is maintained.
Good image information can be obtained, and the reliability of image reading accuracy can be maintained.

[Brief description of the drawings]

FIG. 1 is a schematic side view of a fax machine to which an embodiment of the present invention is applied.

FIG. 2 is a schematic side view of the image reading apparatus according to the embodiment of the present invention when reading an image.

FIG. 3 is a schematic side view at the time of shading correction of the image reading apparatus according to the embodiment of the present invention.

FIG. 4 is a perspective view of the attachment of the reading roller and the support means in the embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating how the reading roller and the support means are mounted in the embodiment of the present invention.

FIG. 6 is a side view illustrating a holding position of a clutch and a support unit when an image is read by the image reading apparatus according to the embodiment of the present invention.

FIG. 7 is a side view illustrating a holding position of a clutch and a support unit at the time of shading correction of the image reading apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Contact image sensor 2 Original 3 Reading roller 4 Supporting means 4a Separation part 5 Shading member 5a Cleaning part 18 Clutch C Image reading position

Claims (4)

[Claims] An image reading apparatus comprising: a contact type image sensor for reading image information of a document; and a reading roller for conveying the document while pressing the document against the image sensor by rotating in one direction. Support means rotatably supported, supporting a base end of a shading member made of a white sheet for performing shading correction,
A clutch for rotating the support means by a predetermined amount with respect to the reading roller by rotation of the reading roller; and moving the shading member to a reading position of the image sensor by rotating the reading roller in the other direction, thereby performing shading correction. An image reading apparatus, comprising: 2. An image reading apparatus according to claim 1, wherein said shading member has a cleaning section for cleaning said image sensor. 3. An image reading apparatus according to claim 2, wherein said cleaning section is provided at an end of said shading member opposite to said base end. 4. An image reading apparatus according to claim 1, wherein said support means has a separation portion for separating said reading roller and said image sensor during shading correction. Reader.