JPH0336875A - Image reading device - Google Patents

Abstract

PURPOSE:To attain picture reading with fidelity to an original by coating an upper face of a shield member with a black paint, forming a transparent section as a slit shape and limiting the range of the original to be lighted. CONSTITUTION:A shield member 9 is provided at a read position 5 and when an original S is carried in a carry path L, the member acts like a guide. Moreover, the member 9 is coated with a black paint 10 as an opaque substance and masking is applied to the remaining transparent part so as to provide a slit shape in parallel with the original carrying direction. Then the light from a light source 4 is subjected to limit of the range lighted by the original S because the transparent part is shaped as a slit resulting that the region playing a role in the secondary light source is made narrow. Then a read means does not read the information other than the prescribed picture information and reads the density information of the original S with fidelity thereby improving the picture quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an image reading device such as a facsimile, and particularly to an image reading device that reads a document while moving it relative to the main body of the device.

[Prior Art] Conventionally, there is a device of this type as shown in FIG.

In this method, a document S conveyed by a conveyance means consisting of a paper feed roller 101 and a paper discharge roller 102 is illuminated by a light source 103 such as a fluorescent lamp serving as an illumination means, and the light reflected from the document S by this light source 103 is illuminated at a predetermined level. From the reading position 104 through the reflecting mirror 105 and the imaging lens 106,
The light is guided to a light receiving element 107 such as a CCD and read out sequentially. The original S is placed at the reading position 104.
A transparent shield member 108 is provided to prevent paper dust and the like from entering the apparatus main body 100, and this shield member 108 also serves as a document guide on the conveyance path.

[Problems to be Solved by the Invention] However, in the conventional example, the light source 1 illuminates the surface of the document S over a fairly wide range in the conveyance direction of the document S.
03, there were problems as described below.

As shown in FIG. 9(a), when reading a document S1 that has a thin white background W in a black background B,
Even if the surface is illuminated over a wide area, the black background B reflects almost no light, so the device can only read the image information of the white background W, but as shown in FIG. 9(b), When reading a document S2 with an entirely white background W having the same brightness as the white background W, if illumination is performed over a wide range in the transport direction, the reflected light from the white background W surface of the document S2 will act as a secondary light source. It repeats mutual reflection with surrounding nearby objects, and the reflected light is also read as image information.
A phenomenon occurs in which the output of the light-receiving element 107 is higher for the document S2 than for the document St, even though the brightness of the document S2 is equal to that of the document St. That is, there is no problem in the case of binarization processing in which the presence or absence of image information on the document S is read based on the threshold value, but there is no problem in the case of multi-value processing based on the output result of the light receiving element 107. For the reasons mentioned above, the white of the original S2 is affected by the surrounding image information to be read, and is recognized as brighter than the white of the original S1, which deteriorates the reproducibility of halftones. Ta.

The present invention has been made to solve the problems of the prior art described above, and its purpose is to read an image faithfully to a document without being affected by the surrounding image information of the image to be read. The goal is to do the following.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a conveyance means for conveying a document having image information, an illumination means for illuminating the document conveyed by the conveyance means, In the image reading device, the image reading device includes a reading means for reading light reflected from the document surface by the illumination means at a predetermined reading position, and a transparent shield member disposed between the reading means and the document, the shield member being opaque. Masking is applied by the substance,
The transparent portion has a slit shape parallel to the document conveyance direction.

[Function] In the present invention having the above configuration, the portion where the document is illuminated is masked with an opaque substance in the transparent shield member so that the transparent portion has a slit shape parallel to the document conveyance direction. By making the width narrow with respect to the conveying direction of the document, the illumination of the document surface does not become wider than necessary.

Further, by blocking unnecessary reflected light from the document surface from being guided to the reading means by the masked shield member, the reading means does not read information other than the image information to be read.

[Embodiment] A first embodiment of the present invention is shown in FIGS. 1 to 3, and its configuration will be explained based on FIG. 2.

Reference numeral 1 designates the main body of the image reading device, 2 a paper feed roller that feeds the document S, and 3 a paper discharge roller that discharges the document S. I am doing it. 4 is a light source such as a fluorescent lamp as a lighting means;
The light reflected from the surface of the document S illuminated by this light source 4 is directed from a predetermined reading position 5 to an imaging lens 7 by a reflecting mirror 6.
The light is guided to a light receiving element 8 such as a COD, and sequentially read as the document S is conveyed. The reflecting mirror 6, the imaging lens 7, and the light receiving element 8 constitute a reading means. Reference numeral 9 denotes a transparent shield member provided at the reading position 5. This shield member 9 acts as a document guide when the document S is conveyed along the conveyance path, and also serves as a document guide while the document S is being conveyed into the apparatus main body 1. This is to isolate the original S and the reading means so that fine paper dust and the like generated from the S do not enter. Further, the shield member 9 has a transparent portion 9a on its upper surface coated with black paint lO as an opaque substance as shown in FIG.
Masking is performed so that a has a slit shape parallel to the document conveyance direction.

Next, an example of the reading operation of this embodiment will be explained based on FIG. 3.

First, when the document S is set in a predetermined position, the presence of the document S is detected by a detection sensor (not shown), and the document S
are separated and fed one by one by a paper feed roller 2. The original S is guided to a reading position 5 by a shield member 9, and at this reading position 5, the reflected light from the surface of the original S illuminated by the light source 4 is sequentially read as the original S is conveyed. .

Here, the light from the light source 4 is as shown in FIG.
Since the black paint 10 applied to the upper surface of the shield member 9 forms the transparent portion 9a into a slit shape, the document is illuminated in a narrowed range (hereinafter referred to as the document illumination area). The area that serves as a secondary light source is narrowed.

Furthermore, even if the surface of the document S plays the role of a secondary light source, the effects of mutual reflection and the like can be reduced by masking the light from this secondary light source with the black paint 10.

Next, a second embodiment of the present invention will be described based on FIG. 4. Note that the same parts as in the first embodiment are given the same reference numerals, and the explanation thereof will be omitted.

The shield member 9 in this embodiment has a slit 22 formed of a black member 21 adhered to the upper surface of the transparent shield member 9.

Therefore, there is no need to take the trouble to provide the transparent portion of the shield member with a slit shape as in the previous embodiment, and according to this embodiment, it can be easily implemented in conventional devices currently in use. be.

Next, a third embodiment of the present invention will be described based on FIG. In this embodiment, like the second embodiment, the same parts as in the first embodiment are denoted by the same reference numerals, and the explanation thereof will be omitted.

The shield member 9 in this embodiment is masked with a black member 31 as an opaque material on both the upper and lower surfaces of the transparent shield member 9, and the lower surface has a slit 32 for illumination light and a slit 32 for image reading. A slit 33 is formed.

Therefore, in this example, by masking the upper and lower surfaces of the shield member, compared to the previous example,
The document illumination area can be narrowed down more effectively.

Next, a fourth embodiment of the present invention will be described based on FIG. 6. In this embodiment, like the second embodiment, the same parts as in the first embodiment are denoted by the same reference numerals, and the explanation thereof will be omitted.

In the shield member 9 in this embodiment, masking with a black member 41 as an opaque material is applied only to the lower surface of the transparent shield member 9, thereby forming a slit 42.

Therefore, as shown in FIG. 6, even when the original is conveyed in close contact with the shield member, the black member 41 is not peeled off or damaged due to friction between the original and the shield member. .

The other configurations and operations are the same as those of the first embodiment, so their explanation will be omitted.

Note that, as shown in FIG. 7, the present invention is also applicable to a case where the illumination system is configured using a reflective member 51 facing the light source 4.

Further, in this embodiment, black paint, black material, etc. are used as the opaque material, but the material is not limited to this, and any material may be used as long as it suppresses the reflection of light and has light blocking properties.

The masking means is not limited to coating, and may be, for example, printing, vapor deposition, or the like.

[Effects of the Invention] As explained above, in the present invention, the illumination of the document surface does not become wider than necessary, thereby suppressing the generation of secondary light sources that adversely affect image reading. can.

Furthermore, even if the secondary light source is generated, the reading means does not read any information other than the image information to be read, so that the original information is less susceptible to the influence of peripheral original information, and the original density information It is possible to read images with high fidelity, and in particular, the quality of images read in halftones is improved.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the main parts of a first embodiment of the present invention, FIG. 2 is a schematic sectional view showing the entirety of FIG. 1, and FIG. 3 is a diagram illustrating the reading operation of the first embodiment. FIG. 4 is a perspective view showing a main part of a second embodiment of the invention, FIG. 5 is a partial sectional view showing a third embodiment of the invention, and FIG. 6 is a portion showing a fourth embodiment of the invention. 7 is a partial sectional view showing an application example of the present invention, FIG. 8 is a schematic sectional view showing the entire conventional example, and FIGS. 9 (a) and (b) explain problems with the conventional example. This is a diagram for Explanation of symbols 1...Device main body 4...Light source (illumination means) 5
...Reading position 9...Shield member IO...
・Black paint (opaque substance) Figure 1 Figure 4 Figure 6 Figure 7 Figure 8

Claims (1)

[Scope of Claims] A conveyance means for conveying a document having image information, an illumination means for illuminating the document conveyed by the conveyance means, and a light reflected from the surface of the document by the illumination means is read at a predetermined reading position. In an image reading device comprising a reading means and a transparent shield member disposed between the reading means and a document, the shield member is masked with an opaque material, and the transparent portion is parallel to the document conveyance direction. An image reading device characterized by having a slit shape.