JPH03227167A - Image sensor - Google Patents

Abstract

PURPOSE:To correct an output level of a photodetection section of a photodetector sensor uniformly by providing a luminous quantity adjustment film for each picture element to an original read position of a transparent cover. CONSTITUTION:A photodetector sensor 11 in which a transparent cover 3, a light emitting element 6 and a photodetector are arranged and an optical system 8 for the photodetector sensor are provided to a frame 2. A light from the light emitting element 6 passes through the transparent cover 3 and radiates to an original read position B and the optical system 8 projects a light reflected in an original at the original read position B and transmitting through the transparent cover 3 to a photodetector section D of the photosensor 11 for each picture element. A luminous quantity adjustment film 4 is provided for each picture element at the original read position B of the cover 3 to correct an output level of the photodetection output section D of a sensor 9 uniformly. The luminous quantity adjustment film corrects the output level of the photodetector section with the adjustment of the transmission rate of a resin film. The forming and adjustment of the luminous quantity adjustment film 4 are required, but an expensive correction circuit is not required and the cost of the image sensor is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to an image sensor used for reading originals in facsimile terminals.

(b) Conventional technology FIG. 5 shows a cross section of a conventional image sensor.

In FIG. 5, 22 is a frame, and a transparent cover glass 23 is attached to the upper surface of the frame. A light source substrate 25 is attached to the light source attachment position 22b of the frame 22. An LED chip 26 is bonded onto the light source substrate 25, and a lens 27 is attached to cover the LED chip.

A light receiving sensor substrate 30 is attached to the bottom surface of the frame 22. On this light-receiving sensor substrate 30, a light-receiving sensor having an array of light-receiving parts, for example, a photodiode array chip 31, is die-bonded.

Further, at the optical system fixing position 22a of the frame 22, an optical system for the light receiving sensor, for example, a refractive index gradient type lens array (
A lens array (trade name: SELFOC Lens Array) 28 is fixed with screws (not shown) or the like.

The light emitted from the lens 27 passes through the cover glass 23 and is irradiated onto the document reading position B. At the document reading position B, the light reflected from the document A passes through the cover glass 23 again, is received by each light receiving section of the photodiode array chip 31 for each pixel by the refractive index gradient lens array 28, and is converted into an electrical signal. converted.

(c) Problems to be Solved by the Invention The conventional image sensor described above includes an LED chip 26, a refractive index gradient lens array 2, and a photodiode array 3.
Due to variations in the characteristics of the first class, the output level of each pixel varies. Therefore, conventionally, an external circuit for shading correction is provided to uniformly correct the output level of each pixel.

However, when an external circuit for shading correction is provided, there is a problem in that the price of the image sensor increases.

The present invention has been made in view of the above, and aims to provide an image sensor that uniformly corrects the output level of each pixel without increasing the price.

(d) Means and operation for solving the problems The configuration of the image sensor of the present invention will be explained using FIG. 1 corresponding to one embodiment. A frame 2 is provided with light receiving sensors 11 arranged in rows and an optical system 8 for the light receiving sensors, and light from the light emitting element 6 is transmitted through the transparent cover 3 and irradiated onto the document reading position B. , the optical system 8 receives the light reflected from the original at the original reading position B and transmitted through the transparent cover 3 into the light receiving portion of the light receiving sensor 11 for each pixel, and A light amount adjustment film 4 for adjusting the light amount for each pixel is provided at the document reading position B, and the output level of each light receiving portion of the light receiving sensor 9 is uniformly corrected.

This light amount adjustment film 4 adjusts the ratio of the part that transmits light to the part that hardly transmits light or the overall transmittance for each pixel, so to speak, optically corrects the output level of each light receiving part. are doing. Although the process of forming and adjusting the light amount adjustment film 4 is required, there is no need to provide an expensive correction circuit, and the price of the image sensor can be reduced accordingly.

(E) Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIGS. 1 and 3 are a cross-sectional view and an exploded perspective view of an example image sensor. 2 is a frame made of aluminum alloy or the like. A transparent cover glass 3 is attached to the upper surface of the frame 2. Transparent here means
This means that it transmits light of the wavelength used, and it is not necessarily limited to being colorless and transparent in visible light.

A light source substrate 5 is attached to the light source attachment position 2b of the frame 2. On this light source substrate 5 is an LED chip 6.
are bonded at predetermined intervals in the longitudinal direction of the image sensor (perpendicular to the plane of the paper in FIG. 1). A plastic lens 7 is mounted on the light source substrate 5 to ensure illuminance at the document reading position B.

A refractive index gradient lens array 8 is fixed to the optical system fixing position 2a of the frame 2 with screws or resin (not shown). The refractive index gradient lens array 8 causes a light receiving section, which will be described later, to receive light reflected from the document at the document reading position B.

A light receiving sensor substrate 10 is attached to the lower surface of the frame 2. On this light receiving sensor substrate 10, photodiode array chips 11, . . . are arranged in the longitudinal direction of the image sensor.
- 11 are lined up and die-bonded, and covered and protected with resin 12. For example, 64 light receiving sections are arranged in a row on the photodiode array chip 11, forming a straight line in the longitudinal direction of the image sensor. Furthermore, elements constituting the circuit shown in FIG. 4 are also mounted on the light-receiving sensor substrate 10, but are omitted in FIGS. 1 and 3.

A connector 9 is also attached to the frame 2 (see FIG. 1). The terminals 9a of the connector 9 are connected to the light source board 5 and the light receiving sensor board 1 by lead wires (not shown).
Connected to 0.

FIG. 2 is an enlarged view showing the document reading position B on the surface of the cover glass 3, and the left-right direction on the paper corresponds to the longitudinal direction of the image sensor. At document reading position B, one pixel corresponds to a 4×4 grid area Pi.

Some of the grids in this area P have a resin film 4 baked on them, making it difficult for light to pass through (shown with diagonal lines)
. Depending on the number of resin films 4, the amount of light reaching the light receiving section corresponding to the area P1 can be adjusted, and the output level of each light receiving section can be uniformly corrected.

FIG. 4 shows the circuit configuration of the example image sensor for one photodiode array chip 11.

Each light receiving part D64 of the photodiode array chip 11,
. . , Dl light reception signals are respectively sent to the voltage conversion circuit 13-
ha, . . . 13-3 converts it into a voltage signal. 14 is a shift register, which has 64 shift cells 1
It is composed of 4-64,... 14-. “high” SI in cell 14-ba of shift register 14
When the N signal is input, each time the clock signal CLK is input, "h i g h" shifts the cell one bit at a time, and with the "high" signal, the switching element 15-64, 15-63 %... 15-1 are turned on sequentially.

The output sides of the switching elements 15-i4, . . . 15-1 are commonly connected, and each voltage conversion circuit 13-64
,... The analog signals from 13-I are sequentially applied to the corresponding switching elements 1 in synchronization with the clock signal CLK.
5-bl, ... 15-1, tracking/
The analog/digital (A/D) converter 16 is manually operated,
It is converted into a 4-bit digital signal (DO to D3) and output to the outside.

The resin film 4 is formed after the assembly of the image sensor 1 is completed and the output level of each pixel at the bright level is measured. Naturally, at this point, the output level of each pixel varies.

The inner lining of the pixels is also based on the low output level, and in order for the output level of each pixel to match this reference level, a photosensitive resin is burned onto the grid in the corresponding area P with a laser to form the resin film 4. . For pixels whose original output level is higher than the reference level, it is necessary to bake a large amount of resin film 4 in the corresponding area to increase the amount of light to be blocked.

In the image sensor 1 of this embodiment, since the output level of each pixel, that is, each light receiving section is optically corrected to be uniform, so to speak, shading correction using an external circuit is not necessary. Therefore, as shown in FIG. 4, it is possible to immediately convert the voltage-converted light reception signal into digital data and output it to the outside.

Of course, it is also possible to output analog signals as they are, and the design can be changed as appropriate.

In the above embodiment, the output level is corrected by adjusting the ratio of the resin film 4 in the region P, that is, the portion where little light transmits, but the resin film is not formed over the entire region P. , a configuration may be adopted in which the transmittance of the entire resin film is adjusted to correct the output level.

(f) Detailed Description of the Invention As described above, the image sensor of the present invention is characterized in that a light amount adjustment film is provided at the original reading position of the transparent cover to adjust the amount of light for each pixel.

Therefore, an external circuit for shading correction is not required, and the cost can be reduced. It also has the advantage of being able to have smaller external dimensions.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an image sensor according to an embodiment of the present invention, FIG. 2 is an enlarged view of the main part of the image sensor at the document reading position, and FIG. 3 is an exploded perspective view of the image sensor. FIG. 4 is a block diagram illustrating the circuit configuration of the image sensor, and FIG. 5 is a sectional view of the conventional image sensor. 2: Frame, 3: Cover glass, 4: Resin film,
6: LED chip, 8: Refractive index gradient lens array, 11: Photodiode array chip, B: Original reading position.

Claims (1)

[Claims] (1) A frame is provided with a transparent cover, a light-emitting element, a light-receiving sensor in which a light-receiving section is arranged in a row, and an optical system for the light-receiving sensor, and the light from the light-emitting element is transmitted through the transparent cover. and the optical system receives light reflected from the original at the original reading position and transmitted through the transparent cover, into a light receiving part of the light receiving sensor for each pixel, An image sensor characterized in that a light amount adjustment film is provided at a document reading position of the cover to adjust the amount of light for each pixel, and the output level of each light receiving section of the light receiving sensor is uniformly corrected.