JPH0828790B2 - Reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is directed to, for example, miniaturization of a facsimile apparatus, and a photoelectric conversion element array substantially corresponding to a detected object in a dimension of 1: 1 is provided. The present invention relates to a reading device such as a contact image sensor that is arranged.

[Prior art and its problems]

Recently, the development of a contact image sensor has been activated, and FIG. 3 shows an example of the sensor. The light detection unit 2 which is substantially 1: 1 in size with the document 1 is closely attached to the document 1. Then, the light emitting diode 3 projects the original 1 and the reflected light is received by the photodetector 2. In the figure, arrows A and B indicate the main scanning direction and the sub scanning direction, respectively.

FIG. 4 is a sectional view of the photodetector 2 in the sub-scanning direction, which is a reader already proposed by the applicant of the present application.

That is, a transparent substrate 4 made of glass is attached to a substrate support 5 composed of a metal frame, and a common electrode 6 formed by vapor deposition of CR is formed on the substrate 4 and the common electrode 6 is formed. 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 corresponding to each photoelectric conversion section 7. Further, Cr is vapor-deposited so as to cover a part of the transparent electrode 8, and then photoetching is performed, whereby the lead electrode 9 made of Cr is individually connected to each element, and then the common electrode 6 is formed. The light passage hole 10 common to the photoelectric conversion portion 7 and the transparent electrode 8 is individually formed by photoetching. Then, a transparent protective layer 11 made of silicon oxide, silicon nitride, silicon oxynitride, or the like is formed on the uppermost portion.
In addition, a long recess 12 is formed in the substrate support 5 in the main scanning direction, and a plurality of LEs are provided at the bottom of the recess 12.
D chips 13 are arranged at a predetermined interval.

According to the reading device configured as described above, the LED chip 13
The document 1 is projected 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 10 and is received by the photoelectric conversion unit 7.

FIG. 5 shows a photoelectric conversion element array as viewed in the direction of arrow C in FIG. 4, and this photoelectric conversion element array 14 has a light passage hole.
An array of 10 is shown. Furthermore, a lead electrode 9 is individually connected to each element, and the electrode 9 is patterned as a lead 15 on the substrate. The above-described light receiving system is common to each element, and as each element receives light, an individual read signal is sequentially derived one-dimensionally through the lead 15 for each element.

According to the reader having such a configuration, the amount of light received by each element depends on the amount of light projected from the array of LED chips 13 and passing through the individual light passage holes 10.
Since the amount of light passing therethrough is determined by the illuminance distribution of the array of LED chips 13, the LED chip array is set so that the illuminance distribution is uniform with respect to the array of light passing holes 10. Moreover, when the reading device is driven, a part of the light reflected by the original 1 among the light incident through the light passage hole located in the element adjacent to the element is also projected to each element. Light is projected under the same conditions over the respective elements, so that the respective elements receive the same amount of light received with respect to the object to be detected having the same color tone.

However, the elements at both ends of the photoelectric conversion element array 14 are
14a has a problem that the element adjacent to it is chipped on one side, so that the amount of light received by the element 14a is smaller than that of other elements, and as a result, the read signal of the element becomes small. .

Also, the leads 15a connected to the elements 14a at both ends described above.
Has the problem that the same lead is not wired on one side as compared with other leads, which causes surface leakage from the lead and the level of the signal derived in the dark state differs from that of other elements. is there.

That is, if this problem is explained with reference to FIG. 6 viewed from the direction of arrow D in FIG. 4, in the other elements except the elements 14a at both ends, the individual electrodes are in the dark state (the state where no light is irradiated to the elements). A very small current between the and common electrode (this is called dark current, usually less than 1pA)
In contrast, in the elements 14a at both ends, as shown by the arrow S, the amorphous silicon photoelectric conversion portion 7
It is easy for the current to flow on the surface of the
It is about several tens of pA, which is significantly higher than the 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, which causes a problem that an accurate read signal cannot be obtained.

[Object of the Invention]

Therefore, the present invention has been completed in view of the above,
The purpose 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 other elements, so that read signals of the same level can be obtained under the same reading conditions over all of the elements. The purpose of the present invention is to provide a reading device. Another object of the present invention is to provide a reader 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 in a portion corresponding to the element array, the light source projects a detection object, and the reflected light is received by the photoelectric conversion element array. Then, in the reading device capable of sequentially obtaining the read signals from this element array in time series, a reading element characterized in that a dummy element is formed adjacent to the photoelectric conversion element at the end of the photoelectric conversion element array. A device is provided.

 Hereinafter, the present invention will be described in detail.

According to the embodiment shown in FIG. 1, each element 14 in the photoelectric conversion element array of the reader shown in FIG.
The dummy element 16 is formed adjacent to the element 14a at the end of the dummy element 16a.
It is important that the same light passage hole as other elements is formed. As a result, the document 1 is projected through the light passage hole in the dummy element 16, and a part of the reflected light projects the element 14a at the end portion, and as a result, all the photoelectric elements including the element 14a at the end portion are projected. The conversion elements may have the same amount of received light with respect to the detected object having the same color tone.

Further, according to the present invention, the LED chip 13 as the light source is
Dummy element in the dark state when is off
It is preferable to set 16 so that it has substantially the same potential as the reading element 14, and for that purpose, for example, each electrode of both elements 14 and 16, that is, the lead 15 of the element 14 and the lead of the dummy element 16 are provided. It suffices to ground it, which eliminates the surface leak of current (arrow S in FIG. 6) that occurs on the surface of the amorphous silicon photoelectric conversion portion 7 near the leads 15a connected to the elements 14a at both ends in the dark state. Element 14a on both ends
The level of the signal derived in the dark state is approximately the same as the level of the signal derived from other elements. The bright state, which is compared with the dark state, means that the LED chip 13 is lit,
This is a case where the irradiation light is reflected by the original 1 and the reflected light is received by the reading element 14.

Further, according to the present invention, when forming the dummy element 16, it is preferable to set the light passage area of the light passage hole to be larger than that of the reading element 14.

That is, to explain the reason in detail, in the bright state (light receiving state), the light receiving changes the potential of the reading element, whereas when the dummy element 16 is grounded, The potential of the element 16 does not change, which causes a potential difference between the element 14a at the end and the dummy element 16 and causes a current leak in a direction corresponding to the change in potential of the reading element and reducing the potential. , As a result, the end element 14
The read signal of a becomes slightly smaller. For this problem,
The area of the light passage hole of the dummy element is defined by the photoelectric conversion element array 14
If the light receiving amount of the element 14a at the end portion is increased by making the area larger than the area of the light passage hole, the decrease in the read signal of the element at the end portion can be complemented.

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. 2, so that the dark state and the bright state of the element 14a at the end may be different. This is desirable in that the conditions of the reading element of (1) are further made the same.

[Advantages of the Invention] As described above, according to the reading device of the present invention, all photoelectric conversion elements have equal light receiving conditions, and even in both the dark state and the bright state, the same output signal is obtained under the same conditions. Therefore, an accurate and highly reliable reading device can be provided.

The reading device of the present invention is not limited to the above-mentioned embodiment, and various modifications and improvements can be made without departing from the scope of the present invention.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a photoelectric conversion element array of a reading device according to the present invention and a signal derivation lead pattern thereof, FIG.
The figure is an explanatory view 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 view showing the arrangement of the reading device according to the present invention with the object to be detected, FIG. 4 is a sectional view of the reading device in the sub-scanning direction, and FIG. 5 is a photoelectric conversion element array in a conventional reading device. Explanatory diagram showing a signal derivation lead pattern thereof,
FIG. 6 is a sectional view of the reading device in the main scanning direction. 1 ... Original, 2 ... Photodetector 3 ... Light emitting diode, 4 ... Substrate 6 ... Common electrode, 7 ... Photoelectric conversion unit 8 ... Transparent electrode, 9 ... Extraction electrode 10 ... Light passage hole , 14 …… Photoelectric conversion element array 15 …… Lead, 16 …… Dummy element

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H04N 1/028 A

Claims (1)

[Claims] 1. A photoelectric conversion element array comprising a layered photoelectric conversion section and a common electrode and an individual electrode respectively arranged on both main surfaces of the photoelectric conversion section is formed on a substrate, and the photoelectric conversion element is formed. A light source is provided in a portion corresponding to the array, the light source projects the object to be detected, and the reflected light is received by the photoelectric conversion element array so that read signals can be sequentially obtained from the photoelectric conversion element array in time series. In the reading device,
A dummy element was formed adjacent to the photoelectric conversion element at the end of the photoelectric conversion element array, and the individual electrode of the dummy element was grounded so as to have the same potential as the individual electrode of the photoelectric conversion element in the dark state. A reading device characterized by the above.