JPS63187964A - Reader - Google Patents

Abstract

PURPOSE:To obtain the read signals of a same level under a same read condi tion over all the elements by setting the lightreceiving quantity of the elements positioning in both ends of a photoelectronic conversion element array to the same degree as other elements. CONSTITUTION:In the photoelectric conversion element array of a reader, the dummy elements 16 are formed adjacent to both end parts of the read elements 14. The same light-passing pores as other elements are formed in the dummy elements 16. Thus, an original is lighted through the light-passing pores in the dummy elements 16, and a part of the reflected light beams projects the elements 14a of the edge parts. Consequently, all the photoelectric conversion elements including the elements 14a of the end parts have same light-receiving quantity with respect to the detected body of a same color tone. Here, the dummy elements 16 and the read elements 14 are set so that they substantially have same potential in a dark state, and the level of the signal of the elements 14a in both ends derivated in the dark state is set to the same degree as the level of the signals derivated from other elements.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a photoelectric conversion element array that is designed to reduce the size of, for example, a facsimile machine, and has a dimensionally 1:1 correspondence with an object to be detected. The present invention relates to a reading device such as a contact type image sensor, which is equipped with a contact type image sensor.

[Prior art and its problems]

Recently, the development of contact image sensors has become more active.
FIG. 3 shows an example of such a sensor, in which a light detection section 2, which corresponds dimensionally to the original 1 at a ratio of 1:1, is brought into close contact with the original 1.
The light emitting diode 3 emits light onto the original 1, and the light detecting section 2 receives the reflected light. Note that arrows A and B in the figure represent the main scanning direction and the sub-scanning direction, respectively.

FIG. 4 is a cross-sectional view of this photodetector 2 in the sub-scanning direction.
This is a reading device already proposed by the applicant.

That is, a transparent substrate 4 made of glass is attached to a substrate support 5 made of a metal frame, and a common electrode 6 made of vapor-deposited Cr is formed on this substrate 4. A photoelectric conversion section 7 made of amorphous silicon is formed on the photoelectric conversion section 7, and a transparent electrode 8 made of ITO is formed on the photoelectric conversion section 7 in correspondence with each photoelectric conversion section 7. Furthermore, Cr was vapor-deposited to cover a part of this transparent electrode 8, and then photo-etched.
As a result, the extraction electrode 9 made of Cr is individually connected to each element, and then the common electrode 6 and the photoelectric conversion section 7 are connected.
A light passage hole 10 common to the transparent electrode 8 is individually formed by photoetching.

A transparent protective layer 11 made of silicon oxide, silicon nitride, silicon oxynitride, or the like is formed on the top. Further, a long recess 12 is formed in the substrate support 5 in the main scanning direction, and a plurality of LED chips 13 are arranged at a predetermined interval at the bottom of the recess 12.

According to the reading device configured as described above, the LED chip 1
3 projects light onto the original 1 through the substrate 4, the light passage hole 10, and the protective layer 11, and the reflected light passes through the transparent electrode 8 near the light passage hole IO and is received by the photoelectric conversion section 7.

FIG. 5 shows a photoelectric conversion element array 1 seen from the direction of arrow C in FIG. 9 are individually connected, and the electrode 9 is connected to the lead 15.
A wiring pattern is formed on the board. The light receiving system described above is common to each element, and as each element receives light, an individual read signal is one-dimensionally and sequentially derived from each element via the lead 15.

According to the reading device having such a configuration, the amount of light received by each element depends on the amount of light emitted from the array of LED chips 13 and passing through each light passage hole 10, is determined by the illuminance distribution of the array of LED chips 13, so the LED chip array is set so that the illuminance distribution is uniform with respect to the array of light passing holes 10. Furthermore, when the reading device is driven, part of the light reflected by the document 1 is also projected onto each element through the light passing hole located in the element adjacent to that element. Light is projected to each element under the same conditions, and as a result, each element receives the same amount of light for an object to be detected of the same color tone.

However, both ends of the photoelectric conversion element array 14
In the element 14a of ', each of the adjacent elements is missing on one side, and as a result, the amount of light received by that element 14a is smaller than that of the other elements, and as a result, the read signal of that element becomes smaller. There's a problem.

Also, some parts 15 may be connected to the elements 14a at both ends described above.
A is the problem that the same lead is not wired on one side compared to the other leads, and this causes surface leakage from that lead, resulting in the level of the signal derived in the dark state being different compared to other elements. There is.

That is, to explain this problem with reference to FIG. 6 viewed from the direction of the arrow in FIG.
), but there is a very small current (
This is called dark current and is usually less than 1p^)
On the other hand, in the elements 14a at both ends, as shown by the arrow S, the current flows easily on the surface of the amorphous silicon photoelectric conversion section 7, and this current is several p.
A ~ several tens of p^, which is significantly larger than the above-mentioned dark current. Therefore, the level of the signal derived in the dark state of the elements at both ends is different from the level of the signal derived from the other elements, resulting in a problem that accurate read signals cannot be obtained.

[Purpose of the invention]

Therefore, the present invention was completed in view of the ridges,
The purpose of this is to make the amount of light received by the elements located at both ends of the photoelectric conversion element array about the same as that of other elements, so that read signals of the same level can be obtained from all elements under the same reading conditions. The object of the present invention is to provide a reading device that has the following characteristics. Another object of the present invention is to provide a reading device in which the level of the signal derived in the dark state is the same across all elements.

[Means for solving problems]

According to the present invention, a photoelectric conversion element array is formed on a substrate, a light source is provided at a portion corresponding to the element array, the light source projects light onto a detected object, and the photoelectric conversion element array receives the reflected light. and a reading device capable of sequentially obtaining read signals from the element array in time series, characterized in that a dummy element is formed adjacent to the photoelectric conversion element at an end of the photoelectric conversion element array. Equipment is provided.

The present invention will be explained in detail below.

According to the present invention, for example, in the photoelectric conversion element array of the reading device shown in FIG. 4, the dummy element 16 is formed adjacent to the element at the end thereof. It is important that the element 16 has light passage holes similar to those of the other elements. As a result, light is emitted from the original l through the light passing hole in the dummy element 16, and a portion of the reflected light is emitted to the end element 14a, and as a result, all the photoelectrons including the end element 14a are illuminated. The conversion element can receive the same amount of light for objects of the same color tone.

Further, according to the present invention, in the dark state, the dummy element 16
is preferably set to have substantially the same potential as the reading element 14, for example, both elements 14 and 16.
This eliminates the surface leakage of the current (arrow S in FIG. 6) that occurs on the surface of the amorphous silicon photoelectric conversion section 7 connected to the elements 14a at both ends or near the gate 15a in the dark state. As a result, the level of the signal derived from the dark state of the elements 14a at both ends becomes comparable to the level of the signal derived from the other elements.

Further, according to the present invention, when forming the dummy element 16, the light passage area of the light passage hole is determined by the reading element 14.
It is best to set it so that it is larger than that of .

That is, to explain the reason in detail, the bright state (light receiving state B)
, the potential of the reading element changes due to the reception of light, but on the other hand, if the dummy element 16 is grounded, the potential of that element 16 does not change, and as a result, the potential of the element 14a at the end portion changes. A potential difference is generated between the dummy element 16 and the dummy element 16, and a current leak occurs in a direction corresponding to the change in the potential of the read element and decreases, and as a result, the read signal of the end element 14a becomes slightly smaller. To solve this problem, if the area of the light passing hole of the dummy element is made larger than the area of the light passing hole of the photoelectric conversion element array 14 and the amount of light received by the end element 14a is increased, the amount of light received by the end element 14a can be increased. It is possible to compensate for the decrease in the read signal.

As another embodiment of the present invention, a plurality of elements may be formed at both ends of the element array as shown in FIG. This is desirable in that the conditions are even more identical to those of the reading element.

〔Effect of the invention〕

As described above, according to the reading device of the present invention, all the photoelectric conversion elements have equal light receiving conditions, and furthermore, it is possible to obtain very similar output signals under the same conditions in both the dark state and the bright state. , Thereby, an accurate and highly reliable reading device can be provided.

Note that the reading device of the present invention is not limited to the above-mentioned embodiments, and various modifications and improvements may be made without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a photoelectric conversion element array and its signal deriving lead pattern of a reading device according to the present invention, and FIG.
The figure is an explanatory diagram of a photoelectric conversion element array and its signal derivation lead pattern showing another example of the reading device according to the present invention,
FIG. 3 is a schematic diagram showing the arrangement of a reading device according to the present invention with a detected object, FIG. 4 is a sectional view of the reading device in the sub-scanning direction, and FIG. 5 is a photoelectric conversion element array and a conventional reading device. FIG. 6 is an explanatory diagram showing the signal deriving lead pattern thereof, and FIG. 6 is a sectional view of the reading device in the main scanning direction. 6... Common electrode 7... Photoelectric conversion section 8... Transparent electrode 9... Extracting electrode 10... Light passing hole 1
4... Photoelectric conversion element array 15... Lead 1
6... Dummy element patent applicant (663> Kyocera Corporation Representative Kinju Anjo ↓0 Figure

Claims (1)

[Claims] A photoelectric conversion element array is formed on a substrate, and a light source is provided at a portion corresponding to the element array.The light source emits light onto the object to be detected, and the photoelectric conversion element array receives the reflected light. 1. A reading device capable of sequentially obtaining read signals in time series, characterized in that a dummy element is formed adjacent to a photoelectric conversion element at an end of the photoelectric conversion element array.