JPH09116695A - Sheet for shading for image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow the shading sheet to have provision for approaching its detected face to an original and to be less damaged from the original. SOLUTION: A PET(polyethylene terephthalate) being a thermoplastic resin is used for a base material 20 of a white background sheet 11 to detect shading correction data, a film formed by coating a hard paint to a detected face at the lower side of the base material 20 in a thickness of 6 to 8μm is employed for a protection film 21 coating the detected face, and the protection film 21 prevent the detected face from being damaged due to friction with a rear side of the original and then the detected face is set closer to the original.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in an image reading apparatus in which reading information is read by a reading sensor and shading correction data is detected, and the shading correction data used for detecting the shading correction data is used. Regarding the seat.

[0002]

2. Description of the Related Art Conventionally, an image reading apparatus in which digital image processing is performed is generally provided with a means for performing shading correction for the purpose of correcting the performance change of the reading device or the light amount distribution of a light source. There is. The specific structure of the means includes a shading sheet or a shading plate installed between the lens and the light source. The shading sheet is arranged so as to face a contact glass, which is a document mounting table, for a document to be conveyed, and the sheet white ground is read by the reading sensor before reading the document, and the white is read from the reading sensor. Data for correcting the reference (shading correction data) is output.

Normally, in the shading correction, the white output of the reading sensor when the shading sheet is read is used as a white reference. Therefore, if the surface to be detected of the shading sheet is dirty, an incorrect correction is applied when the document is read. It will be.

The dirt on the shading sheet means
Not only the stains are transferred from the original written with a pencil, but also the scratches are generated due to the rubbing against the back surface of the original. In fact, the sheet damaged by the scratches is more likely to be stained.

Therefore, various structures have been conventionally implemented and proposed to prevent the shading sheet from becoming dirty. For example, in the document reading device disclosed in Japanese Patent Laid-Open No. 4-40058, in order to prevent the white background sheet and the document from contacting each other,
Before the document is read, the white sheet is sent to the reading sensor by the sheet feeding means, and the white output data is detected from the white sheet so that the document is not slid or damaged on the surface to be detected of the white sheet. I have to.

[0006]

The above-mentioned shading
The importance of preventing stains on a sheet is increasing as a high-resolution contact image sensor is developed and used.

That is, the contact image sensor has a short focal length, and it is necessary to bring the document close to the contact glass. Therefore, the distance between the contact glass and the shading sheet must be narrowed. Therefore, the back surface of the original easily comes into contact with the shading sheet, and the shading sheet easily becomes dirty. Further, since the contact image sensor basically has a structure and characteristics that increase the resolution, it is naturally easy to read the dirt on the shading sheet. As described above, increasing the resolution is improving the MTF and making the read line density finer, but on the other hand, there is a problem that the image becomes more sensitive to dirt and the noise of the read image is easily picked up.

An object of the present invention is to provide a shading sheet for an image reading apparatus, which can cope with a structure in which a surface to be detected is brought close to an original and is less susceptible to damage.

[0009]

In order to achieve the above object, the present invention is used in an image reading apparatus in which original information is read from an original by a reading sensor, and the reading sensor detects shading correction data. In the shading sheet for reading, a colorless and transparent sheet protection film is provided on the white ground for the detection.

Further, a thermoplastic resin sheet is used as a base material, and a colorless and transparent hard paint is applied on the surface to a thickness of 6 to 8 μm.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an image reading apparatus using a shading sheet for explaining one embodiment of the present invention, in which 1 is a document setting table and 2 is a document setting table 1.
Pickup rollers 3 and 4 are installed to face each other, and separation rollers for feeding and separating the originals one by one and a feed roller, 5 and 6 are original feed roller pairs, and 7 is an original feed roller pair 5 and 6. The contact image sensor 8 is provided, 8 is a pressurizing unit described below for bringing the document into close contact with the contact image sensor 7, and 9 is a pair of conveying rollers.

FIG. 2 is an enlarged view of the contact image sensor and the pressing portion of FIG. 1, 10 is a pressing pipe having a rectangular cross section, and 11 is a shading sheet attached to the bottom surface of the pressing pipe 10. White sheet, 12 is the contact image sensor 7
A contact glass, which is installed above the pressure pipe 10 and below the pressure pipe 10, is a guide portion for guiding the conveyance of the document.

1 and 2, when a plurality of originals are stacked and set on the original setting table 1 and the reading operation is started,
The pickup roller 2 separates the original document in the direction of the roller 3 (arrow A
Paper). The fed originals are separated and conveyed one by one by a separation roller 3 and a feed roller 4, as is well known, and pass through a pair of conveying rollers 9 and a pair of original conveying rollers 5, 5.
6 moves on the contact glass 12 while maintaining the linear velocity.

The document moves between the white background sheet 11 and the contact glass 12 while being pressed against the contact glass 12 by the pressure pipe 10, and the contact image sensor 7 reads the document information. Further, before the reading of the document information, the white background of the white sheet 11 is read by the contact image sensor 7 and the shading correction data (white reference data) is detected as is known.

The original for which the detection of the shading correction data and the reading of the original information have been completed are discharged by the original feeding roller pair 6 to the outside of the apparatus (in the direction of arrow B).

Since the white sheet 11 is pressed against the contact glass 12 side by the pressure pipe 10,
The flatness of the sheet is stabilized, and the distance from the contact glass 12 is kept constant.

As an example of the white background sheet 11, as shown in the enlarged sectional view of FIG. 3, PET (polyethylene terephthalate) which is a thermoplastic resin is used as the base material 20, and the surface to be detected (base material) is used as the protective film 21. The hard coating is applied to the lower side of 20) in a film form by applying 6 to 8 μm. By thus providing the protective film 21, it is possible to prevent the detected surface from being damaged by rubbing against the back surface of the original. Therefore, the detection of the shading correction data becomes accurate and reliable. In addition, the use of the white background sheet 11 having the above-mentioned configuration does not reduce the degree of freedom of processing as a sheet including the maintenance of flexibility, and even if the sheet is arranged in the conveyance path, it may obstruct the document conveyance. Nothing.

Further, as a matter of course, by reducing the film thickness of the hard paint, the degree of freedom of the sheet can be further increased, and further, the cost can be reduced and the manufacturing process can be simplified. As a specific example of the material, a sheet in a so-called electronic blackboard is obtained by using ICI Japan Co., Ltd., trade name Merynex as the white base material of the white background sheet, and using Dick Co., Ltd. hard paint as the hard paint. Will be used.

[0020]

As described above, according to the shading sheet of the image forming apparatus of the present invention, the surface to be detected is protected and it is possible to suppress the generation of scratches and stains due to the sliding of the document, and to accurately and long-term. Since the shading correction data can be reliably detected, stable shading correction can be performed, and therefore, it is possible to sufficiently cope with the use of the high-resolution contact image sensor in which the distance between the document and the detected surface is shortened. become.

Furthermore, the flexibility of the sheet is not impaired, the sheet is easy to use, does not hinder the document transportation, and is advantageous in cost.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image reading apparatus using a shading sheet for explaining an embodiment of the present invention.

FIG. 2 is an enlarged view of the contact image sensor of FIG. 1 and a pressing portion.

FIG. 3 is an enlarged cross-sectional view for explaining the configuration of the white background sheet in the present embodiment.

[Explanation of symbols]

7 ... Contact image sensor, 8 ... Pressure part, 11 ... White sheet, 12 ... Contact glass, 20 ... Base material, 21 ... Protective film.

Claims (2)

[Claims] 1. A shading sheet which is used in an image reading apparatus in which original information is read from an original by a reading sensor and which is read by a reading sensor for detecting shading correction data. A shading sheet for an image reading apparatus, which is provided with a colorless and transparent sheet protection film on a white ground. 2. A thermoplastic resin sheet is used as a base material,
The shading sheet for an image reading apparatus according to claim 1, wherein the surface is coated with a colorless and transparent hard paint having a thickness of 6 to 8 µm.