JPS5814073B2 - Photoelectric conversion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photoelectric conversion device having a size corresponding to 1=1 with a document used in a reading system of a facsimile machine or the like.

Conventionally, as shown in FIG. 1, in a reading system for a transmitted document such as a facsimile machine, a transmitted document 1 is uniformly illuminated with an illumination light source 2 such as a fluorescent lamp, and the reflected light is transmitted through a lens 3 to a photoelectric conversion device. In this case, the photoelectric conversion device 4 is a MOS or CO
Since the chip size is about 20mm manufactured using IC technology such as D, A, (200x
290mm2), the reduction ratio of the lens is 1/1.

Since the distance from the transmission document 1 to the photoelectric conversion device 4 is considerably large, there is a drawback that the device becomes large in size.

On the other hand, instead of using lenses as an optical system,
As shown in FIG. 2, reflected light from a transmission document 1 illuminated by an illumination light source 2 such as a fluorescent lamp is transmitted to a large sensor array 6 through a light guiding system 5 such as a simple light guide or optical fiber. There are also known methods of guiding.

In this case, the distance between the document and the sensor can be significantly shortened compared to a system that uses lenses, and the overall size can be reduced, but it is difficult to align the light guide system and the sensor. There were also drawbacks such as the expensive optical system.

As a method for solving the above-mentioned drawbacks, a method has been proposed in which the sensor and the document are brought into close contact with each other and the document is directly read without using a light guiding system.

In this method, as shown in FIG. 3, a row of light-receiving elements 8 is formed on a transparent substrate 7, and a transparent protective layer 9 is provided on top of the array.

In addition, in FIG. 3, electrodes and wiring relationships are omitted.

In FIG. 3, a luminous flux 10 from an illumination light source 2 placed below a translucent substrate 7 passes through a gap between the translucent substrate 7, a light receiving element 8, and a transparent protective layer 9, and illuminates a transmission document 1. However, the reflected light is captured by the light receiving element 8 and photoelectrically converted.

In this case, the photoelectric conversion output obtained from the light receiving element is the light flux that directly illuminates the light receiving element from the illumination light source (which becomes interference light).
10' and the reflected light beam from the document surface (which becomes signal light) are combined, and this interference light has the drawback of lowering the S/N ratio.

The present invention provides a close reading type photoelectric conversion device that is provided with a light-shielding layer that prevents direct illumination of the light-receiving element array in order to eliminate the drawbacks of the conventional example.

Hereinafter, embodiments will be described in detail with reference to the drawings.

FIG. 4 shows an embodiment of the present invention, in which 1 is a manuscript;
2 is an illumination light source such as a fluorescent lamp, I is a transparent substrate, 8 is a light receiving element array (electrodes are omitted), 9 is a transparent protective layer, 10
The document is illuminated in the illumination light emitted from the light source 2, and the reflected light reaches the light receiving element 8, and 10' is also the light source 2.
Among the illumination light emitted from the light receiving element, 11 is a light-shielding layer that blocks the light flux (interfering light) that goes directly to the light-receiving element. The shape of 11 should be slightly larger than the size of the light receiving element.

Further, reference numeral 12 denotes a transparent insulating layer that is continuously applied to cover the light shielding layer 11.

Next, the operation of this embodiment will be explained.

First, the light beam 10 emitted from the light source 2 illuminates the original 1 through the gap between the light shielding layers 8, the transparent insulating layer 12, and the transparent protective layer 9, and the reflected light from the original 1 is captured by the light receiving element 8. Converted to Kyuden.

Further, a portion 10' of the illumination light beam is a light beam that goes directly to the light receiving element 8, but because it is blocked by the light shielding layer 11, it does not reach the light receiving element 8 and does not become interfering light.

Therefore, a close-contact reading type photoelectric conversion device with a high signal-to-noise ratio can be constructed. Furthermore, in the configuration of the present invention, the light-shielding layer 11 is composed of a non-light-transmitting metal layer and a light-transmitting insulating layer covering the metal layer, and is electrically independent from the light-receiving element 8 formed thereon. Therefore, it also has the feature that there is a large degree of freedom in selecting the light receiving element and its electrode material.

FIG. 5 shows another embodiment of the present invention, in which the light shielding layer 1
The structure is similar to that of the embodiment shown in FIG. 4, except that the transparent insulating layer covering 1 is separate, and the operation thereof is also similar to that of the embodiment shown in FIG.

Note that in this configuration, a transparent layer is formed on the light shielding layer 11. Instead of stacking insulating layers, if a metal whose surface layer can be easily oxidized, such as Ta or Si, is used as a light-shielding layer, Ta205 or SiO
Since it is possible to form an oxide film such as on the surface, the manufacturing process is simplified.

Furthermore, when insulating layers are individually applied, there is no effect even if the light transmittance is slightly poor, so there is a greater degree of freedom in selecting the insulating layer.

FIG. 6 shows an example of the shape of the light shielding layer 11 of the present invention, where the same reference numerals as in FIG. (electrodes are omitted), Fig. 6b shows a case where the light-shielding layer is a stripe, and Fig. 6c shows a case where the light-shielding layer is continuous and has an opening between the light-receiving elements. It shows.

As explained above, the present invention provides a large image sensor that irradiates light from the back side of a transparent substrate and reads a document placed closely to the front side using reflected light. By providing a light-shielding layer consisting of a non-transparent metal layer and a transparent insulating layer, it is possible to prevent light from directly hitting the light-receiving element from the back surface, resulting in an excellent signal-to-noise ratio and the possibility of miniaturization. Therefore, it has the advantage that it is not only useful as a facsimile sensor, but can also be used satisfactorily as a sensor for pattern recognition, mark league, etc.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a conventional reading system for a transmission document such as a facsimile machine, and FIG. 2 is a perspective view of a conventional reading system using a dog-shaped sensor and a light guide system such as an optical fiber.
Figure 3 is a partial cross-sectional view of the conventional close reading method;
FIG. 5 is a partial cross-sectional view of another embodiment of the present invention, and FIG. 6 is a partial cross-sectional view showing an example of the shape of the light-shielding layer of the present invention. FIG. 2 is a diagram and a plan view. 1... Transmission original, 2... Light source, 3... Lens, 4... Photoelectric conversion device, 5... Light guiding system, 6... Large image sensor, 7... Transparent substrate, 8... Light receiving Element, 9... Transparent protective layer, 10... Illumination luminous flux, 11... Opaque metal layer, 12
...Translucent insulating layer.

Claims (1)

[Claims] 1 A light-transmitting insulating substrate has a plurality of or continuous non-transparent layers on one surface thereof, and a light-transmitting insulating layer covering the non-transparent layers individually or continuously, and the non-transparent layer has A photoelectric conversion element is formed on each corresponding light-transmitting insulating layer, light is irradiated from the other surface of the light-transmitting insulating substrate, and a document placed in close contact with the one surface is read by reflected light. A photoelectric conversion device characterized by: