JPS6264161A - Line image sensor - Google Patents

Abstract

PURPOSE:To obtain a line image sensor discriminating two clors by arranging photodetectors on two different straight lines on least one of which is laminated with a color filter in the line image sensor. CONSTITUTION:When a red filter is formed over the entire face of all photodetectors 1b of a photodetection section 1B, a photodetection section 1A detects all white colors and the photodetector section 1B detect only the red color. Thus, a black picture and a red picture are read discriminatively. It is preferred that the interval (d) between the photodetector 1a and the photodetector 1b is nearly the same as the pitch interval (l) between the photodetectors 1a and 1b. When the interval is nearly the same, electric outputs afterward from each photodetection group are regarded that as if they were picture photoelectric conversion outputs from the same line on an original by retarding the output from one group among output electric signals from each photodetection group electrically.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a line image sensor used in document image reading devices and the like, and particularly to a line image sensor suitable for distinguishing between two colors.

[Background of the invention]

Conventional line image sensor
As described in the document titled "Image sensor for reading" published in Vol. It became. However, no consideration was given to distinguishing between two colors, such as receiving light separately for a black image and a red image. Therefore, for two-color discrimination reading such as black and red images, the optical path must be set so that the red light enters one line image sensor and the other light enters the other line image sensor. It was necessary to install a spectrometer, which required a complicated optical system.

[Purpose of the invention]

The present invention has been made in view of the problems of the prior art described above, and does not require the use of a complicated optical system.

The purpose of this invention is to provide a line image sensor that can distinguish between two colors.

[Summary of the invention]

The present invention achieves its purpose by providing a line image sensor with a spectral function. That is, the line image sensor of the present invention is characterized in that it consists of a plurality of light receiving elements having a photoelectric conversion function, and the light receiving elements are arranged on two different straight lines. A color filter is stacked on at least one of the straight lines.

Note that if a single color filter is not stacked on either of the plurality of light receiving elements arranged on two straight lines, the document can be read with twice the pixel density of the conventional method.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in more detail with reference to embodiments shown in the accompanying drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention. In FIG. 1, the light receiving sections IA, IB are composed of a large number of light receiving elements 1a, lb, and the light receiving elements 1a, lb are arranged so as to form groups on two different straight lines. Moreover, each light receiving element 1a.

15 is electrically connected to different analog shift registers 2a and 2b as shown. In an image line sensor having such a configuration, for example, if a red filter is formed over the entire surface of all the light receiving elements 1b of the light receiving part IB, the light receiving part IA receives all the light (white light), but the light receiving part IA receives all the light (white light). Portion IB receives only red light, and therefore can distinguish and read a black image and a red image. Light-receiving element 1a in light-receiving part IA and light-receiving element 1b in light-receiving part IB
It is preferable that the distance d between the light receiving elements 1a and 1b is approximately the same as the distance (receiving element pitch) Ω between the respective light receiving elements 1a and 1b. By electrically delaying the output, the subsequent electrical output from each light receiving unit group can be easily realized as if it were an image photoelectric conversion output from the same line on the original.

With such a configuration, it is of course possible to read a two-color image with two colors separated, but if a color filter is not placed in each of the two groups, the black image will be read twice as much. It is also possible to read at pixel density. That is, in this embodiment, since the light receiving elements 1a and 1b are provided alternately on two different straight lines, it is possible to read with twice the pixel density when no color filter is mounted. Therefore, when a single color filter is always mounted, it is not necessary to provide the light receiving elements 1a and lb alternately on two different straight lines.

Generally, the positional error of the color filter formed on the entire surface of the light receiving portion IB is within the range of ±2 μm or 2 μm. However, if the distance a between the adjacent light receiving elements 1b is 10 μm, the dimensions of the light receiving elements 1a and 1b will be 5 μm square, and by setting the distance d between the light receiving elements 1a and 1b to be 2Q, that is, 20 μm, the light receiving elements 1a and 1b will be 5 μm square. A region with no light receiving element having a width of 10 μm can be formed between 1b. By providing a region where no light-receiving element exists in this way, the positional error (about 2 μm) accompanying the formation of the color filter is sufficiently absorbed, and the color filter can be formed with high precision in front of the light-receiving element 1b.

Note that the organic color filter has a different coefficient of expansion from the inorganic material forming the light receiving element 1b, so that if it is formed into a long length, it will break. In order to prevent this breakage, it is preferable to provide a portion where no color filter is formed in a region where no light receiving element is present between the light receiving elements 1b forming the color filter.

As is clear from the above description, according to the first embodiment described above, errors in forming the color filters are allowed.

Two-color discrimination reading is possible while preventing the occurrence of breakage due to stress after the formation of the brown filter.

FIG. 2 is a block diagram showing a second embodiment of the present invention, and the same parts as in the first embodiment shown in FIG.

The difference from the first embodiment shown in FIG. 1 is that a multi-stage signal delay analog shift register 3b is connected to the last stage analog shift register 2b. This multi-stage signal delay analog shift register 3b has twice the number of stages as the analog shift register 2b. For example, the total number of light receiving light elements is 3456, and one light receiving section LA,
When the number of IB light receiving elements 1a and lb is 1728, the analog shift register 2b is provided with 1728 stages,
The analog shift register for signal delay has 3456 stages. By adding such a multi-stage analog shift register 3b for signal delay, each light receiving section IA
, IB can be treated as if they were obtained from the same line on the bridge at the same time. Therefore, it can be handled in the same way as a conventional line image sensor in which all the light receiving sections are arranged on the same line.

As is clear from the above explanation, the above-mentioned 1. .

According to the second embodiment, positioning when forming color filters is easy, and two-color discrimination reading is possible without causing defects such as breakage of one-color filters. It is possible to read with twice the pixel density, and by adding an analog shift register on the line image sensor chip, the reading position of the two colors can be placed on the same line on the document. can.

In addition, the above-mentioned 1. In the second embodiment.

Although the configuration is such that a color filter is laminated on one of the light receiving sections IB, the present invention is not limited to this. For example, it may be configured such that color filters of different colors are laminated on both the light receiving sections IA and IB. Also good.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, it is possible to provide a line image sensor capable of distinguishing between two colors without providing a complicated optical system.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the present invention;
The figure is a block diagram showing a second embodiment of the present invention. IA, IB...light receiving section, la, lb...light receiving element,
2a, 2b...shift register, 3b...shift register.

Claims (1)

Claims: 1. A line image sensor comprising a large number of light receiving elements having a photoelectric conversion function, characterized in that the light receiving elements are arranged on two different straight lines. 2. The line image sensor according to claim 1, wherein light receiving elements are arranged alternately on the two different straight lines. 3. The line image sensor according to claim 1, wherein the interval between the two different straight lines is the same as the pitch of each light receiving element. 4. The line image sensor according to claim 1, wherein a color filter is laminated on the light receiving elements arranged on at least one of the two different straight lines. 5. The line image sensor according to claim 1, further comprising means for delaying an output signal from a light receiving element arranged on one of the two different straight lines.