JPS61185967A - Close-contact image element - Google Patents

Abstract

PURPOSE:To provide a contact type image element which can read out data in real time, by using a photoconductive film which is formed by firing material having a specific photoconductor/glass binder ratio in inert gas atmosphere. CONSTITUTION:On an insulating substrate 1, common electrodes 2, a photoconductive film 3 and discrete electrodes 4 with a stripe shape are pro vided. The discrete electrodes 4 are divided into blocks each having a plural of then, which are commonly connected with the corresponding electrodes of every block by matrix wiring 6. Since CdSe or photoconductor containing it for forming a contact type image element has a very high photoconductivity and has a clear-dark ratio of about 10<3> under illumination of 695nm, 30lx, a one-dimensional contact type image element which can produce a signal over 1muA as a photo current and can adopt a real time reading out system, can be provided. In order to produce the image element, material in which the ratio of photoconductor/glass binder is selected within a range of 10/2-10/0.1 is fired in inert gas atmosphere by heat treatment of 400-600 deg.C. Thus a contact type image element can be provided at low cost and with a better yield.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an elongated contact type image element of the same size as the width of an original using CdSe alone or a photoconductive material containing CdSe as a photoelectric conversion film. In particular, the present invention relates to a contact image element that improves the image signal output characteristics of a photoelectric conversion element and simultaneously improves the photoresponse characteristics of the element, making it possible to employ a real-time image readout method.

<Summary of the Invention> The present invention provides, for example, CdSe that has been previously subjected to activation heat treatment.
A CdSe-based photoconductive film formed by firing the same with a glass binder is used in a contact type image element to improve the image signal output characteristics and photoresponse characteristics of the element.

<Prior Art> One-dimensional image elements are used as image input elements for office automation equipment such as facsimiles and intelligent copiers. Conventionally, as this type of light receiving sensor, a one-dimensional solid-state image device (CCD or MOS type) is used to obtain a corresponding image information signal by slit exposure and reduction imaging of an original image. This -dimensional solid-state image element is I
The device is manufactured using C technology and is approximately 30 mm in size. Therefore, an optical system with a long optical path length must be used to guide the reflected light from the original to the light receiving section, making the device more compact. is difficult. Furthermore, such an apparatus requires complicated adjustment of the optical system, and also causes problems such as a decrease in the amount of light at the periphery of the screen and a deterioration in resolution.

In order to improve these problems, a so-called contact type image element has been devised, which uses a long image element having the same length as the document width and forms a close image using a fiber lens array. Such an element requires a large photoelectric conversion section and requires the formation of a uniform photoelectric conversion film over a large area.

<Problems to be solved by the invention> Currently, amorphous silicon thin films and the like have been proposed for making long image elements, but since the signal current is weak, an accumulation type readout method has not been adopted. There is. In this method, in order to increase the speed, the switches for pixel selection are of a one-to-one correspondence type, which is disadvantageous in terms of the number of switches and increases costs.

On the other hand, contact image elements using photoconductive films such as CdS can obtain sufficiently high signal outputs, making it possible to use a real-time reading method, enabling matrix-type driving, and reducing the number of switching elements. It has advantages. However, when fabricating by vacuum evaporation method,
It has a major drawback in that it is difficult to obtain reproducibility because the deviation from the stoichiometric composition changes depending on the manufacturing conditions.

The present invention has been made in view of the various problems of the conventional contact type image elements described above, and is aimed at providing a contact type image element capable of real-time readout with a high yield. be.

Means for Solving the Problems> The present invention provides a contact type image element that converts optical information into an electrical signal according to the light intensity by utilizing resistance changes of the photoconductor, in which the photoconductor is made of CdSe. Single or CdS
The photoconductive film is composed of a CdSe-based photoconductive film containing CdSe, and the photoconductive material containing CdSe alone or CdSe that forms this photoconductive film has an average particle size of 0.2 μm, which is precipitated by a chemical precipitation method. CdSe raw powder of CuCl
2 and/or AgCl as an impurity of 0.1 to 1 mol, and is activated by firing at 600 to 800°C for 30 to 60 minutes in an inert gas atmosphere to impart photoconductivity. This is what I did.

FIG. 1 shows the structure of a contact type image element according to an embodiment of the present invention, with FIG. 1(a) being a plan view and FIG. 1(b) being a sectional view.

In FIGS. 1(a) and (b), 1 is an insulating substrate, 2
3 is a common electrode, 3 is a photoconductor film, 4 is an individual electrode, 5 is an insulating layer, and 6 is a matrix wiring, which are processed into a common electrode 2, a photoconductor film 3, and a stripe shape on an insulating substrate I. Individual electrodes 4 are provided, divided into a plurality of blocks, and the corresponding electrodes of each block are commonly connected by an IJ Fuchs wire 6.

FIG. 2 is a diagram showing an example of the basic circuit configuration of the contact type image element according to the present invention, and in the same figure, R11.

RI2・RIB・”'R31・R32・RBB are photoconductors, Cl・c2.c3 are common switches, Il, 12.1
3 is an individual switch, E is a power source, and RL is a load.

<Function> The device configuration of the present invention described above does not require a blocking diode to prevent crosstalk, and by employing matrix wiring, the number of switching elements can be significantly reduced, making the device easy to fabricate. Cost reduction can be achieved.

As the switching element, for example, a C-MOS transistor is used, and when each gate is connected to a shift register and switching operations are performed sequentially, the photoconductor forming each pixel exhibits a resistance change depending on the amount of light received. Image information can be read as a signal current.

The CdSe alone or the photoconductor containing CdSe used for producing the contact image element of the present invention exhibits extremely high photoconductivity, with a brightness ratio of about 10 when irradiated with light at 695 nm and 30 Ax. A signal of 1 μA or more can be obtained as a current, and it becomes possible to obtain a one-dimensional contact type image element employing a real-time readout method.

In addition, this photoconductor has excellent photoresponse characteristics and
90%) and falling (9 (1%) both 5 m5
It exhibits a fast response of less than ec, and exhibits extremely favorable characteristics as a high-speed reading element.

Even in the case of a film having a dark room conductivity of 10 to 20 μm and having such a dark room conductivity as to cause leakage between adjacent pixels, it is possible to easily divide the pixels.

Hereinafter, the manufacturing process of the contact type image element according to the present invention will be explained in more detail.

<Example 1> Corning #7059 was used as an insulating substrate, Cr was evaporated at a density of about 2,000×BE on this substrate at a substrate temperature of 200° C., and the pixel portion (linear density 8 1/mm) and a matrix wiring lower wiring were formed. The paste for forming a photoconductive film consists of CdSe microcrystalline powder (CuCl
20.4 Mortidobe.

N2 atmosphere 800℃ treatment) CDC+23 morti.

Four glasses of low melting point glass (Tg: 400° C.) were added to the total weight and an appropriate amount of oil (1.5 wt % ethyl cellulose) for adjusting the viscosity was added, followed by mixing in a ball mill for 24 hours. This paste was applied to the pixel forming area of the electrode wiring board by screen printing to form a photoconductor film, and then heated at 300°C for 1 hour and then at 500°C in an N2 atmosphere.
A heat treatment was performed at ℃/30 minutes to grow and sinter the microcrystalline grains and bind them with a glass binder.

Next, a polyimide resin film was coated on the pixel portion and the matrix wiring portion, and after curing at aOO° C./30 minutes, contact holes were formed in the matrix wiring portion by plasma etching. Afterwards, to form the upper wiring, C
r about 2. oooX BE was deposited, and an upper wiring was formed using a conventional photolithography technique, thereby producing a device consisting of 1728 pixels. Since the polyimide film on the pixel portion serves as a protective film for the photoconductor, there is no deterioration in the characteristics of the photoconductor during the process of forming the upper wiring, and the environmental resistance characteristics can also be improved.

The device created by the above method had a bias voltage of 12V,
A signal current of 8 μA could be read with respect to the incident light of 30 Ax, and the uniformity of each pixel was stable at ±15 inches. Furthermore, the photoresponse speed was 2 m5ec or less, showing excellent response characteristics, making it possible to obtain a high-speed contact type image element using a real-time reading method.

<Example 2> An element was produced in the same manner as in Example 1 except that the proportion of low melting point glass was adjusted to the composition of IEI with respect to the total weight. The characteristics of this device are that a current of 4 μA was obtained under 12 V and 30 tx, but the falling (90%) photoresponse speed was 40 m5e.
c, and the response became poor.

<Example 3> A photoconductive film having the same composition as in Example 1 was heated at 300° C. in an N2 atmosphere.
℃/1 hour, followed by heat treatment at 600° C. to produce an element. As for the characteristics of this device, a current of 1 μA was obtained under +2 V and 30 tx, and a photoresponse characteristic of 5 m 1 lec or less was obtained, but the dark room conductivity increased by about one order of magnitude and a decrease in light-dark contrast was observed. On the other hand, below 450℃, especially 400℃
In the heat treatment described below, the photocurrent obtained was less than 0.1 μA, making it impossible to create a device with a sufficient signal current.

From the various experimental results including the above examples, it has been found that there is an optimal value for the composition ratio of the glass binder and the heat treatment temperature, and that the photoconductor/glass binder ratio is 10% in order to obtain a device that can be put to practical use. /2 to 1010.1 and firing by heat treatment at 400° C. to 600° C. in an inert gas cloud atmosphere.

<Effects of the Invention> As described above, the contact type image element of the present invention does not cause compositional deviation of the photoconductive material, which is a problem with manufacturing methods such as vacuum evaporation, and can be easily manufactured. Since it is configured to include a photoelectric conversion film that has extremely excellent photoconductivity and can obtain high-speed photoresponsiveness, it is possible to provide a contact type image element at low cost and with high yield.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the structure of a contact type image element according to an embodiment of the present invention, in which FIG. 1(a) is a plan view and FIG. 1(b) is a sectional view. FIG. 2 is a diagram showing an example of the basic circuit configuration of a contact type image element according to the present invention. DESCRIPTION OF SYMBOLS 1... Insulating substrate, 2... Common electrode, 3... Photoconductive film, 4... Individual electrode, 5... Insulating layer, 6... Matrix wiring 0 Agent Patent attorney Shi Fuku Aihiko (and 2 others) Figure 1

Claims (2)

[Claims] 1. In a contact type image element that converts optical information into an electrical signal according to the light intensity by using the resistance change of the photoconductor, the photoconductor is made of CdSe alone or CdSe containing CdSe.
It is composed of a dSe-based photoconductive film, and the CdSe-based photoconductive film has a glass transition temperature (Tg) of 3.
Contains a glass binder at a temperature of 00°C to 450°C, and the photoconductor/glass binder ratio is 10/2 to 10 by weight.
/0.1 material in an inert gas atmosphere from 400 to 600
A contact type image element comprising a photoconductive film formed by baking by heat treatment at ℃. 2. The CdSe-based photoconductive film is made of a material consisting of CdSe-based compound particles precipitated by a chemical precipitation method and subjected to an activation treatment to impart photoconductivity and have a particle size of 0.5 μm to 5 μm. A contact type image device according to claim 1, characterized in: