JPS6143869A - Original reader - Google Patents

Abstract

PURPOSE:To attain reading with high resolution by arranging a transparent body between a read means and an original face so as to keep the interval of them constant and read the original stably at all times thereby limiting the reading range with a light shield body provided to the transparent body. CONSTITUTION:The reader consists of a transparent cylindrical body 11 arranged while being closely adhered to a light source 14 and an original 10, linear erect nonmagnification lens groups 12 arranged for a plural number in the main scanning direction and fixed to an upper face of the cylindrical body 11 and a photodetection sensor 13 of linear array in the main scanning direction. Then in this reader, the nonmagnification lens groups 12 and the photodetection sensor 13 constitute a linear array read means. The photodetector sensor senses an information scattering as shown in figure in the sub scanning direction while being placed in a direction deviated from the normal reflecting direction to the lighting light, the normal reflected light being non-information light from the original face is reflected further on a side face 16 on the surface of which a reflection film is applied, then the side face 16 has a curvature around a read point A, then the light is collected again onto the read point A to increase the illuminance of the reading point.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a document reading device that converts information on a document surface such as an image into an electrical signal and reads it out.

2. Description of the Related Art Conventionally, in image information processing apparatuses such as facsimile machines, laser beam printers, and inkjet printers, various reading apparatuses that use photoelectric conversion to read images have been proposed. In recent years, with the improvement of light-receiving sensors, it has become possible to read a wide range of document surfaces.
Furthermore, each pixel (photoelectric conversion element) forming the light receiving sensor,
That is, in the case of reading, it has become possible to form the smallest unit that can be divided and read minutely. Therefore, there is a need for a document reading device having a reading optical system compatible with a light receiving sensor array having such high resolution.

[Summary of the invention]

An object of the present invention is to provide a document reading device having an excellent decomposition source and having a compact structure.

The document reading device of the present invention reads and scans the document surface by moving a one-dimensional array of light-receiving sensors and the document in a predetermined main scanning direction relative to the sub-scanning direction perpendicular to the main scanning direction. Yes, a transparent body is placed between the reading means including such a light receiving sensor and the document surface,
This transparent body keeps these intervals constant and stabilizes the reading accuracy. In addition, by providing a light shielding member with a linear opening in the main scanning direction on the surface of the transparent body facing the document surface, the reading range on the document is limited, and the resolution in the sub-scanning direction, which is approximately perpendicular to the main scanning direction, is increased. It is something that improves.

Note that the document surface used in this specification includes not only the information recording surface but also the surface to be inspected such as the surface to be inspected for flaws.

〔Example〕

The present invention will be described in detail below using the drawings.

In the present invention, a high-resolution light-receiving sensor that can be manufactured from long to short lengths in the array direction is used as a one-dimensional array of light-receiving sensors. A thin film photodiode array made of a high quality semiconductor can be applied, which exhibits excellent photoelectric conversion characteristics in the visible wavelength region, and can be easily made into a long length by vacuum deposition. Although it is a thin film, it has a fast response speed and is chemically stable in air.

FIG. 1 is a diagram illustrating a light-receiving sensor array using the amorphous semiconductor described above, in which the amorphous semiconductor l of the thin film photodiode is connected to a transparent electrode l and metal electrodes 3, 3 as junction ends f-.
' constitute one light receiving sensor unit, which is arranged in an array across the width of the document. The size of each of these light receiving sensor units is adjusted to meet the resolution required for reading the original.
The pitch between each unit is determined. When light 4 is now incident on this light receiving sensor, only the portion that hits the amorphous semiconductor 1 through the transparent electrode 2 is photoelectrically converted, and the information is taken out by a switching circuit 6 controlled by a drive circuit 5.

In this way, 1947 minutes of document information can be extracted from the light receiving sensor as a time-series signal.

FIG. 2 is a perspective view of an apparatus showing one embodiment of the present invention. In FIG. 2, the apparatus includes a light source 14 and a document i.

A transparent cylindrical body 11 is placed in close contact with the cylindrical body 11, a plurality of one-dimensional erect equal-magnification lenses 12 are spaced apart in the main scanning direction and fixed to the upper surface of the cylindrical body 11, and a one-dimensional array is arranged in the main scanning direction. It consists of a light receiving sensor 13 having a shape.

In this embodiment, the equal-magnification lens group 12 and the light receiving sensor 13 constitute a one-dimensional array of reading means. Here, the one-dimensional erecting equal-magnification lens means a lens that has erecting equal-magnification imaging performance in a predetermined one-dimensional direction.

In this embodiment, it is desirable that the line light 1fX13 be as thin as possible in order to increase the resolution in the sub-scanning direction.A halogen light source in the form of a line light source or a xenon light source with a small tube diameter is suitable, and the transparent cylindrical body 11 has good adhesion. It is also possible to add curvature to the surface on the document 10 side in order to increase the curvature.

FIG. 3 shows a cross-sectional view of the present device viewed from the main scanning direction. The document 10 is currently being fed in the sub-scanning direction by the roller 18. Further, the illumination light from the light source 14 is transmitted to the cylindrical body 11.
Since the side surface 15 has a curvature of radius γ, the light is condensed and illuminates a linear portion on the document surface parallel to the main scanning direction. Among the light reflected from the original surface, the light having jXv4 information is transmitted to the one-dimensional erecting equal-magnification lens group 1.
2. Each of these one-dimensional erect equal-magnification lenses maintains an erect, equal-magnification relationship between the document surface and the light-receiving sensor surface in the main scanning direction, but in the sub-scanning direction, it focuses information light from the document surface onto the light-receiving sensor surface. It has the power to shine. This is because in the two-dimensional scanning method as in this embodiment, the light-receiving sensor reads only one amount of information in the sub-scanning direction, and the erect, same-magnification relationship in the teaching scanning direction is not particularly necessary. This is because it is desirable to have a light-concentrating effect in order to

The resolution in the sub-scanning direction depends on how thin a line portion of the document surface can obtain a high amount of information light in that direction. Therefore, it is desirable that the illumination light be focused on one point as much as possible on the document surface within the cross section shown in FIG.
For example, the position of the linear light source and the reading point A may be set so that they are in a conjugate relationship with respect to the refraction action of the side surface 15 of the cylindrical body. Line light source 1 as shown in Figure 4
4 and the center of curvature of the side surface 15 is the reading point A, which is the illumination position.
The distance on the optical axis from reading point A to side 15 is a.
The curvature of the side surface 15 and the position of the linear light source 14 may be determined so as to satisfy the relational expression given by b, where b is the distance from the optical axis to the optical axis. At this time, an image of the line light source 14 is formed in a line shape on the document surface. However, this imaging effect occurs only in the sub-scanning direction, and since the main scanning direction is illuminated with diverging light, uneven brightness on the light source does not become uneven illumination on the document surface.

Furthermore, in the sub-scanning direction, as shown in Figure 3, the light receiving sensor is located in a direction away from the specular reflection direction with respect to the illumination light, and detects information scattered light, and specular reflection light that is non-information light from the document surface. The light is further reflected at the side surface 16 on which a reflective film is applied, and since this side surface 16 is formed to have a curvature centered on the reading point A, the light is focused again on the reading point A. Increase the illuminance of the spot from the reading. In general, sides 15 and 16 do not need to have the same curvature, and such a cylindrical body can be easily made by stamping plastic.

Furthermore, in this embodiment, in order to further increase the resolution in the sub-scanning direction, a slit plate 17 made of a light absorbing material is provided on the document side surface of the cylindrical body, as shown in FIG. This slit is parallel to the main scanning direction and prevents reflected light from other than the reading point from entering the light receiving sensor. The resolution depends on the pitch of the light-receiving sensor array, and the smaller the pitch of the light-receiving sensor array, the higher the resolution of the reading device can be obtained.

In the present invention, it is also possible to perform color reading by providing a stripe filter on the light receiving sensor surface. Furthermore, when reading a document using the device of the present invention, in addition to the method shown in the second embodiment in which the device is fixed and the document is moved in the sub-scanning direction, it is possible to fix the document and move the device. Scanning may also be performed.

〔Effect of the invention〕

As explained above, the present invention maintains a constant distance between the reading means and the document surface by disposing a transparent body between the reading means and the document surface, and reads the document stably at all times. It has the effect of limiting the range and allowing high resolution reading.

[Brief explanation of the drawing]

Fig. fJS1 is a diagram explaining a one-dimensional array of light receiving sensors, Fig. 2 is a perspective view of the first embodiment of the present invention, Fig. 3 is a cross-sectional view of the device shown in Fig. 4, and Fig. 4 is a collection of cylindrical bodies. Diagram for explaining light action. 10--one manuscript, 11-m-cylindrical body, 12--one erect equal-magnification optical system, 13-m-light receiving sensor, 17--slit plate.

Claims (1)

[Claims] (1) a one-dimensional array of reading means in a predetermined direction;
a transparent body disposed between the reading means and the document surface to maintain a constant distance therebetween; and a light shielding body provided on a surface of the transparent body opposite to the document surface to form a linear opening in the predetermined direction. What is claimed is: 1. A document reading device having a body, wherein information on the surface of the document is read by the reading means through the opening.