JPS62200763A - Semiconductor image pickup device - Google Patents

Abstract

PURPOSE:To obtain a device of which a sensor element has a simple structure and a yield of manufacture is high, by a method wherein the sensor element is not divided for each picture element while light-intercepting picture elements of a light-intersecepting means are made transparent for each one of them sequentially so that picture informations held by the picture elements can be read sequentially by photoelectric conversion elements. CONSTITUTION:A sensor 3 composed of photoelectric conversion elements transducing light into electric signals, and a light-intercepting means 2 being capable of intercepting light from the entire area of a light-receiving surface of the sensor 3 and composed of a large number of light-intercepting picture elements arranged in an array or in divisions in the shape of a matrix, are provided. The light-intercepting means 2 is scanned so that the light- intercepting picture elements are made transparent one by one sequentially, and thereby picture signals are taken out sequentially as outputs of the sensor 3. When a liquid crystal cell C11 corresponding to an upper-left picture element is made transparent by a scanning circuit 7 according to an instruction from a processor 6, for instance, a reflected light from a copy is transmitted through the liquid crystal cell C11 and enters the sensor 3. In the sensor 3, this optical input is transduced into an electric signal and outputted to an A/D converter 4, and a binary-coded picture signal is subjected to a compensating process etc. in the processor 6 and then written in a prescribed address of a memory 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor imaging device, and particularly to a semiconductor imaging device using an electro-optic shutter.

[Prior art and its problems]

In recent years, with the development of electronic technology, in the field of imaging devices that convert images such as figures and characters into electrical signals, imaging devices using various semiconductor functional elements such as CCD (charge-coupled device), MOS target, and ntovigicon are being put into practical use. It is becoming more and more popular.

In these imaging devices, an image is formed on point-shaped light receiving elements arranged in a row or in a matrix on a substrate, and the output of each light receiving element is sequentially transmitted, for example, by a scanning circuit built on the same board. A reading method is used.

For example, a contact image sensor that uses a long reading element with a sensor part the same width as the original is made of amorphous semiconductors such as amorphous silicon (a-3i) or cadmium sulfide (CdS)-cadmium selenide (CdSe).
) etc. as a photoconductor layer, it becomes possible to use it as a large-area device that does not require a reduction optical system, and its wide use in small document reading devices is attracting attention. .

One of the basic structures of the sensor section of this image sensor is a sandwich type sensor. As shown in FIG. 3, this sandwich type sensor has a photoconductor layer 14 sandwiched between a lower electrode 12 formed on a substrate 11 and a transparent upper electrode 13. In this case, several sandwich type sensors are installed on a long board (for example, in the case of 8 dots/screen, Japanese Industrial Standards A row 4
1728 pieces for number 4, 2 for number 4 of row B of the same standard.
048) are arranged in parallel, and a matrix drive circuit (not shown) consisting of thin film I transistors is arranged on the substrate.

However, in such an image sensor, the drive circuit and sensor part are formed on the same substrate, and although it is small and easy to connect with wiring, it has a large chip area because it is equipped with a large number of elements, which reduces manufacturing yield. The problem was that it was bad.

Further, in order to enable accurate reading, these sensors must be completely independent from each other and the areas of the light receiving parts must be the same. For this reason, various attempts have been made to define the light receiving area of each sensor on a long substrate.

For example, in the most basic contact type image sensor, as shown in FIG. 4, the lower electrode 12 and the photoconductor layer 14 are formed separately for each sensor, and the translucent upper electrode 13 is also formed separately in important parts. The region where the leading electric layer is sandwiched between the lower electrode 12 and the transparent upper electrode 13 is defined as the light-receiving area (
Each sensor is formed separately.

In this structure, the manufacturing process is complicated because the formation of the lower electrode, the photoconductor layer, and the upper electrode all require the use of a photolithographic etching process.
There were disadvantages such as variations in the light receiving area of each sensor due to pattern misalignment and the like. In addition, during the photolithography process for forming the upper electrode, the edge of the photoconductor layer is contaminated at the boundary with the mask (fi (FJ), resulting in a decrease in reliability and yield. There was also.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a semiconductor imaging device having a simple structure of a sensor section and a high manufacturing yield.

[Means for solving problems]

Therefore, in the present invention, the sensor section is constructed of one or several photoelectric conversion elements for each pixel (without being divided), and a large number of light-shielding pixels divided and formed corresponding to the pixels on the front surface of the sensor section. A light-shielding means capable of shielding the entire light-receiving surface of the photoelectric conversion element is arranged, and the light-shielding pixels of this light-shielding means are sequentially opened pixel by pixel, so that the image information of each pixel is sequentially read by the photoelectric conversion element.

[Effect]

For example, an electro-optic shutter made of liquid crystal is disposed in front of a large-area sandwich-type sensor using an amorphous silicon layer as a photoelectric conversion layer, and the electro-optic shutter is sequentially opened pixel by pixel to scan the sensor. The image can be read by sequentially taking out the output of the electro-optic shutter and recording it in a memory address corresponding to the scanning address of the electro-optic shutter.

In such a device, the sensor only needs to be formed integrally without being divided into pixels, and there is no need to align the sensor with the electro-optic shutter. Since it only needs to be installed so that it is covered with a means, manufacturing is easy and the yield is high.

[Example] Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing an image reading device according to an embodiment of the present invention.

This image reading device includes an optical lens system 1 for guiding light reflected from a document surface (not shown) to a sensor section, a liquid crystal shutter 2 having liquid crystal cells arranged in a matrix, and a liquid crystal shutter 2 disposed behind the optical lens system 1. a sensor section S consisting of a sandwich-type sensor 3, and an A/D converter 4 that converts the output signal of the sensor 3 from analog to digital based on a predetermined reference voltage.
A processor 6 performs predetermined signal processing such as shading correction on the output of the A/D converter and writes it to a predetermined address in the memory 5. In synchronization with the writing operation of the processor to the memory 5, the liquid crystal The scanning circuit 7 determines which liquid crystal cell of the shutter 2 is to be opened and applies a voltage to the liquid crystal cell.

The sensor section S is shown in enlarged views in FIGS. 2(a), 2(b) and 2(c) (FIG. 2(a) is a rear view of the liquid crystal shutter, FIG. 2(b) is a sectional view, FIG. 2(c) is an enlarged cross-sectional view of one pixel), mn liquid crystal cells C1, . . . Cl1In divided into a matrix of m rows and n columns.
As shown by the arrows, a voltage is applied to each one of them so that they become transparent one by one (in the figure, C1□ is transparent), which is detected by the rear sensor 3 and output as an electrical signal.

This liquid crystal shutter is made of a transparent glass substrate, each having a matrix-like wiring layer 201a.

201b and the front substrate 200a and back substrate 200b on which the alignment layers 202a and 202b are formed are spacers 2.
A liquid crystal layer 204 is injected into each cell which is disposed facing each other via the wiring layer 203 and divided into m rows and n columns by the spacer 203.
The liquid crystal cell to which a voltage is applied between 1a and 201b becomes transparent, and the other cells are in a light-shielded state.

The sensor 3 also includes a transparent electrode 301 made of an indium tin oxide (ITO) layer on a transparent glass substrate 300 and a transparent electrode 301 made of an indium tin oxide (ITO) layer.
-Photoelectric conversion layer 3 consisting of a 1-n amorphous silicon layer
02 and a metal electrode 303 made of a chromium (Cr) layer are sequentially laminated to form a sandwich-type photoelectric conversion element.
The sensor detects changes in current generated in the photoelectric conversion layer when light transmitted through the liquid crystal cell enters the sensor.

Since this sensor 3 is a single large-area photoelectric conversion element, high-precision patterning by a photolithography process or the like is not required during manufacturing, and manufacturing is extremely easy, the yield is high, and the cost is low. Furthermore, since the sensor is composed of one photoelectric conversion element, even if the thickness of each layer varies depending on the position, it can be detected as if multiple sensors were formed separately.

There will be no variation in the output signal.

Next, the operation of this image reading device will be explained.

First, when the scanning circuit 7 makes the liquid crystal cell C1□ corresponding to the upper left pixel T1□ transparent according to a command from the processor 6, the reflected light from the document (not shown) passes through the liquid crystal cell C1□. and enters sensor 3.

In sensor 3, this optical input is converted into an electrical signal and A/
It is output to the D converter 4.

Further, the image signal binarized by the A/D converter 4 is subjected to correction processing and the like in the processor 6, and is written to a predetermined address in the memory 5.

Further, the processor outputs a signal for driving the liquid crystal cell C12 corresponding to the next pixel T12 to the scanning circuit 7 in synchronization with the writing of the image information corresponding to the pixel T11 into the memory 5, The liquid crystal cell C12 becomes transparent by voltage application from the scanning circuit 7, and image information is written in the same way.

Then, when the lower right pixel is reached, the process is finished.

In this way, images can be read.

In the embodiment, a liquid crystal shutter was used as the light shielding means, but it goes without saying that the present invention is not limited to this, and other electro-optical shutters such as piezoelectric elements such as PLZT may be used.

Furthermore, the sensor (photoelectric conversion element) is not limited to a sandwich type sensor and can be selected as appropriate. Further, the number of light receiving elements is not limited to one, and if a large area is required, a plurality of light receiving elements may be combined so as to eliminate a dead area.

In addition, in the embodiments, the liquid crystal shutter and sensor are formed separately, or the liquid crystal shutter and sensor are integrated into one, such as by stacking a sandwich-type sensor on the back side of the back substrate of the liquid crystal shutter. It may be formed as follows.

In this case, since the light transmitted through the cell directly enters the sensor, the attenuation of the light is also reduced and the sensitivity is improved.

〔effect〕

As explained in 1., according to the present invention, an imaging device equipped with an advanced function of converting images such as characters and figures into electrical signals can be manufactured at low cost by combining existing electronic components. It can be manufactured at a high yield rate.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an image reading device according to an embodiment of the present invention;
FIGS. 2(a), 2(b), and 2(c) are explanatory diagrams of a sensor section of the same device, and FIGS. 3 and 4 are diagrams showing a conventional image sensor. DESCRIPTION OF SYMBOLS 11... Substrate, 12... Lower electrode, 13... Upper electrode, 17... Photoelectric conversion layer, 1... Optical lens system,
2...Liquid crystal shutter, 3...sensor, 4...A
/D converter, 5... memory, 6... processor, 7
...Scanning circuit, S...Sensor section, 200a...Top substrate, 200b...Back substrate, 201a, 201b
--- Wiring layer, 202 a. 202b... Orientation layer, 203... Spacer, 204
...Liquid crystal layer, 300...Glass substrate, 301...
Transparent electrode, 302... Photoelectric conversion layer, 303... Metal electrode. Figure 1 Figure 2 (G) Section 2 (b) Figure 4

Claims (3)

[Claims] (1) A sensor consisting of a photoelectric conversion element that converts light into an electrical signal, and a large number of light-shielding pixels that can block light over the entire light-receiving surface of the sensor and are arranged in a row or in a matrix. What is claimed is: 1. A semiconductor imaging device comprising: a light shielding means; the light shielding means scans the light shielding means so as to sequentially make the light shielding pixels transparent one by one, and image signals are sequentially extracted as outputs of the sensor. (2) Claim (1) characterized in that the light shielding means is a liquid crystal shutter consisting of a large number of liquid crystal cells.
The semiconductor imaging device described in . (3) The sensor is a sandwich type sensor in which amorphous silicon as a photoelectric conversion layer is sandwiched between a metal electrode and a transparent electrode.
) The semiconductor imaging device described in item 2.