JPH06291938A - Picture reader - Google Patents

Abstract

PURPOSE:To provide a picture reader without picture quality deterioration for a long period by avoiding the use of an area in which a damage is easily caused to a transparent board such as a contact face with an original carrier roller as an incident light reflecting area and providing a white reference face without dirt due to dust depositted onto an original. CONSTITUTION:The reader is provided with a light source 13 from which an original read light is radiated to a side of an original placed onto a transparent board 8 while its picture side is directed downward, an image sensor 2 receiving a read light reflected in the picture side of the original and an original carrier roller 1 arranged to a rear side of the original and carrying the original and executes reading while carrying the original with the original carrier roller, and a maximum weight area A being a contact part between the original carrier roller 1 and the original and an incident light reflecting area B being a part of the picture side of the original into which the read light is made incident and from which the light is reflected are arranged at different positions respectively and a white board 4 is provided in a projecting/retracting way to the incident light reflection area.

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 in a facsimile machine, an image scanner or the like, and more particularly to a document feeding roller which is a drawback of the conventional method in which the outer peripheral surface of the document feeding roller is used as a white reference of an image sensor. The present invention relates to an image reading apparatus capable of preventing image quality deterioration due to dirt on the image.

[0002]

2. Description of the Related Art As a conventional image reading apparatus for reading an original image in a state where an original and an image sensor are opposed to each other through a transparent plate as a contact glass, an original at a reading position of a scanner by an original conveying roller is used. In general, the type is such that a portion is pressed against a transparent plate for reading. That is, as shown in FIG. 8, the incident light reflection area from the light source 13 is made to coincide with the maximum load area A with respect to the paper surface of the original, that is, the area where a straight line passing through the rotation axis of the original conveying roller 1 intersects the transparent plate 8 at right angles. While reading the image,
The surface of the document feeding roller 1 is made white, and the read data is corrected with this as a white reference. However, in the above-mentioned conventional example, in order to generate the document conveying force and to suppress the lifting of the document P, the document conveying roller 1 is configured to be pressed against the transparent plate 8 surface by an appropriate load, and therefore the roller is pressed. 1) and the friction between the original and the transparent plate 8 is likely to cause fine damage on the surface of the transparent plate 8, and these scratches have been a cause of image deterioration in the long term.

In order to solve such a problem, as shown in FIG. 9, an image reading apparatus has been proposed in which the maximum load area A and the incident light reflection area B with respect to the original paper surface are arranged at different positions (Japanese Patent Application Laid-Open No. Hei 10 (1999) -26498). 2-140053). In FIG. 9, 21 is a wear resistant layer, 22 is a transparent layer, 23 is a window, 24 is an image sensor, P is a document, and L is an optical path. As is clear from the figure, since there is no pressure contact or sliding contact between the transparent layer (transparent plate) and the document conveying roller 1 in the incident light reflection area B, the transparent layer is less likely to be damaged.

[0004]

As described above, the image reading apparatus disclosed in Japanese Patent Application Laid-Open No. 2-140053 does not use the area where the transparent plate is likely to be damaged as the incident light reflecting area, which is one of the prior arts. Although the two problems have been solved, there remains a problem that the outer peripheral surface of the conveyance roller, which is the white reference, is easily soiled. As described above, including the prior art described in Japanese Patent Application Laid-Open No. 2-140053, in the prior art, the surface of the document feeding roller 1 is made white and this is used as a white reference. It is easily soiled by dust or the like attached to the original. Therefore, it is not appropriate to use this portion as the white reference.

[0005]

SUMMARY OF THE INVENTION The present invention solves the problems of the prior art as described above, avoids using an area where a transparent plate is likely to be damaged as an incident light reflection area, and is contaminated by dust or the like adhering to an original. An object of the present invention is to provide an image reading device provided with a white reference surface.

[0006]

[Means for Solving the Problems] To achieve the above object,
A light source that irradiates the image reading light onto the image surface of an original placed on a transparent plate with the image surface facing downward, an image sensor that receives the reading light reflected by the image surface of the original, and an image sensor of the original. An image reading apparatus that is provided on the back side of an image surface and that conveys a document, and that is a contact portion between the document conveyance roller and the document in an image reading apparatus that performs a reading operation while the document is conveyed by the document conveyance roller. The maximum load area and the incident light reflection area, which is the portion where the read light is incident on and reflected by the image surface of the original, are arranged at different positions, and a white plate is provided so that the incident light reflection area can appear and disappear. It has a feature.

[0007]

The maximum load area and the incident light reflection area with respect to the original paper surface are arranged at different positions, and the white plate 4 is provided parallel to the transparent plate 8 so as to be retractable in the incident light reflection area. It is possible to use the white plate 4 as a white reference surface, which does not cause the above-mentioned problems and is not soiled by dust or the like attached to the original.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the image reading apparatus of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of a main part of an image reading apparatus according to the present invention, and FIG. 2 is a cross-sectional view showing a document reading state, showing a contact area A between a document feeding roller 1 and a transparent plate 8 which is a contact glass. The incident light reflection area B is arranged at the avoided position, and the incident light reflection area B is provided.
A characteristic is a configuration in which the white plate 4 serving as a white reference is arranged on the transparent plate 8 corresponding to the above so as to be able to move back and forth. That is, the contact area A
The image sensor 2 is arranged on the lower surface of the transparent plate 8 on the upstream side (right side in the drawing) of the above, and the reflected light of the reading light emitted toward the original P on the transparent plate 8 is received by the image sensor 2. A light source 13 is arranged. The document carrying table 3 arranged further upstream of the incident light reflection area B has an end inclined surface 10 for guiding the document P to the contact area A, and is provided between the lower surface of the document carrying table 3 and the transparent plate 8. Opening O formed in
The white plate 4 is configured so as to be able to move forward and backward toward the incident light reflection area B.

In this embodiment, a point A (actually a line) at which a straight line passing through the rotation axis of the document conveying roller 1 intersects the plane of the transparent plate 8 perpendicularly is the maximum load area with respect to the document sheet. That is, as shown in FIG. 2, a document that has entered from the right side through the document transport table 3 is pressed against the transparent plate 8 by the document transport roller 1 around the point A, and the document is transported in that state. It is conveyed to the left in the figure by the rotational force of the roller 1. On the other hand, the image sensor 2 and the light source 13 are arranged as shown in FIG. 2 (or FIG. 1) so that the incident light reflection area B where the incident light from the light source to the document reading surface is reflected is different from the maximum load area. To be done.

The lower surface of the document carrying table 3 is arranged higher than the height of the upper surface of the transparent plate 8, and the white plate 4 is placed between the document carrying table 3 and the transparent plate 8 in parallel with them, as shown in FIG. 1 (or FIG. 3). To set up. A permanent magnet 6 is fixed to the end of the white plate 4, and an electromagnet 7 is fixed to the device body side so as to face the permanent magnet 6. In addition, the permanent magnet 6 is sandwiched between the electromagnets 7
A positioning member 5 is provided on the reflection side. The electromagnet 7
It is possible to change the direction of the magnetic poles by changing the direction of the current flowing through the coil constituting the. Normally (except when the white reference is read), a small current flows in the electromagnet 7 so that an attractive force acts between the permanent magnet 6 and the electromagnet 7, so that the white plate 4 is at the position as shown in FIG. 1 (or FIG. 2). is there. When the direction of the electric current is reversed and the electric current value is increased, a repulsive force acts between the permanent magnet 6 and the electromagnet 7, the white plate 4 moves leftward as shown in FIG. 3, and the permanent magnet 6 moves the positioning member. 5
Stop where it comes into contact with. At this time, since the left side portion of the white plate 4 is on the incident light reflection area B, the read data can be corrected with the lower surface of the white plate 4 as the white reference.

Although a method for returning the white plate 4 to the retracted position shown in FIG. 1 is not shown, for example, when the positioning member 5 is made into an electromagnet and the state shown in FIG. When trying to hold, a force for attracting the permanent magnet 6 is applied to the positioning member 5 so that the white plate 4 moves to the position shown in FIG.
When returning from the protruding state of FIG. 1 to the retracted state of FIG. 1, the permanent magnet 6 is moved to the electromagnet 5 by applying a large current value by reversing the direction of the current of the electromagnetizing positioning member 5.
Is moved to the right (retracting direction) by the repulsive force of, and a large current value in the direction of attracting the permanent magnet 6 is given to the electromagnet 7 at a certain timing. Conversely, 6 may be an electromagnet and both members 5 and 7 may be permanent magnets. It is also possible to use a spring together. The width of the white plate 4 may be set so as to extend over the entire length of the transparent plate 8 in the width direction (direction orthogonal to the document conveying direction), or may be less than that.

FIG. 4 is a sectional view showing another embodiment according to the present invention, and FIG. 5 is a sectional view showing the main part of the embodiment shown in FIG. In the present embodiment, as is clear from the figure, a cleaning member 9 is provided on the lower surface of the end portion of the white plate 4 so that the white plate 4 is slidably contacted with the transparent plate 8 when the white plate 4 is moved back and forth to clean the transparent plate 8.
As the material of the cleaning member 9, felt, linen, or a brush with short bristles can be used. 1 except that the cleaning member 9 is added.
However, in this embodiment, since the cleaning member 9 is provided at the end portion of the white plate 4, the thickness between the original conveying table 3 and the transparent plate 8 is equal to the thickness of the cleaning member 9. The vertical spacing is large.

FIG. 6 shows another embodiment of the present invention, in which a film-like holding member 11 is provided on the end inclined surface 10 of the document carrying table 3. This is for suppressing the lifting of the document and improving the guideability to the area A.

FIG. 6 also shows an example in which a spring 12 which generates a force in a direction to attract the permanent magnet 6 and the electromagnet 7 is used as an alternative to the positioning member 5. Spring 12
After the permanent magnet 6 reaches a predetermined position, the original position (Fig.
Alternatively, a force to return to the position (FIG. 6) is also given. Since the moving speed of the white plate 4 before and after the white plate 4 reaches the predetermined position is very slow, the white reference is read at the timing.

FIG. 7 shows an operation flowchart of the image reading apparatus (embodiment of FIGS. 1 to 3). First, the white reference data is read, and then the original is read. Specifically, when the original is set (step S
1) First, the electromagnet 7 is excited, and the white plate 4 moves in the projecting direction to the state shown in FIG. 3 (S2). At this time, the light from the light source irradiates the white plate 4 to read the white reference data (S3), and after the data reading is completed, the white plate 4 is moved in the retracting direction to return to the state of FIG. 1 (S4). The passage of the original is opened, and the original is read in the incident light reflection area B while moving the original on the transparent plate as shown in FIG. 2 (S
5).

Although the present invention cannot be applied to an image reading apparatus of the type in which the maximum load area with respect to the original paper surface and the incident light reflection area coincide with each other, in that case, the white plate can be moved to the incident light reflection area. In order to achieve this, it is necessary to move the document conveying roller prior to the movement of the white plate, which increases the size of the device and increases the cost. On the other hand, when the two areas are different as in the present embodiment, it is not necessary to move the document conveying roller, so that it can be realized relatively easily as described above. In addition, as described above, the holding member 11
The reason why the floating of the document is suppressed is to prevent the problem of the depth of focus from occurring due to the lifting of the document in the incident light reflection area B.

[0017]

As described above, according to the present invention,
The maximum load area and the incident light reflection area with respect to the paper surface of the original are arranged at different positions, and the white plate 4 which is parallel to the transparent plate 8 and can move forward and backward in the incident light reflection area is provided. As a result, the transparent plate 8 is not damaged, and the white plate 4 that is not soiled by dust or the like attached to the original can be used as the white reference surface, so that it is possible to provide an image reading apparatus that does not deteriorate in image quality for a long period of time.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of an image reading apparatus according to the present invention.

FIG. 2 is a sectional view showing a state in which a document is loaded in the embodiment of FIG.

FIG. 3 is a cross-sectional view for explaining a reading state of the embodiment shown in FIG.

FIG. 4 is a sectional view showing another embodiment of the main part of the image reading apparatus according to the present invention.

5 is a cross-sectional view showing the main parts of the embodiment of FIG.

FIG. 6 is a sectional view showing another embodiment of the main part of the image reading device according to the present invention.

FIG. 7 is a flowchart showing the operation of one embodiment of the present invention.

FIG. 8 is a sectional view showing an example of an image reading apparatus according to a conventional technique.

FIG. 9 is a cross-sectional view showing another example of the image reading apparatus according to the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Original conveying roller, 2 ... Image sensor, 3 ... Original conveying table, 4 ... White plate, 5 ... Positioning member, 6 ... Permanent magnet,
7 ... electromagnet, 8 ... transparent plate, 9 ... cleaning member, 10 ... end inclined surface, 11 ... holding member, 12 ... spring, 13 ... light source, 21
... wear-resistant layer, 22 ... transparent layer, 23 ... window, 24 ... image sensor.

Claims (2)

[Claims] 1. A light source for irradiating an original reading light onto the image surface of an original placed on a transparent plate with the image surface facing downward, and an image sensor for receiving the reading light reflected by the image surface of the original. In the image reading device, which is provided on the back side of the image surface of the original document and which conveys the original document, the reading operation is performed while the original document conveyance roller conveys the original document. A maximum load area, which is a contact portion of the sheet, and an incident light reflection area, which is a portion where the reading light is incident on and reflected by the image surface of the original, are arranged at different positions, respectively, and a white plate which can appear and disappear in the incident light reflection area. An image reading device characterized by being provided with. 2. The image reading apparatus according to claim 1, wherein a cleaning member is provided on a lower surface of an end portion of the white plate, and the upper surface of the transparent plate is cleaned in accordance with a retracting operation of the white plate. apparatus.