JPS6184056A - Photosensor - Google Patents

Abstract

PURPOSE:To dispense with the common wirings to both of a photosensor and a scanning control and readout circuit by a method wherein, when the photosensor is constituted by arraying the plural photoelectric conversion elements in the main scanning direction, the mutually adjacent elements are mutually connected through the mutually different fellow electrodes, the elements are formed in one element row as a whole and the lead-out electrodes for the scanning control and readout circuit are led out from the contact points of these electrodes and the elements and from both sides of the photosensor. CONSTITUTION:Transparent electrodes 14a-14d, each consisting of an ITO film, are coated on an amorphous semiconductor 13, wherein carriers are generated by receiving light, at the prescribed intervals and photoelectric conversion elements 10a-10d are respectively adhered thereon. Then, the lower electrodes 11a and 11c of the elements 10a and 10c are led out in one direction and the lower electrodes 11b and 11d of the elements 10b and 10d are led out in the reverse direction. Moreover, the mutual connections of the mutually adjacent elements 10a and 10b, 10b and 10c, and 10c and 10d are performed using lead-out parts 14', whose polarities are mutually made of differ. The respective electrode is led out in such a way, and the electrodes are used as the lead-out electrodes for the scanning control and readout circuit, and at the same time, are made to function as the common wirings to both of the photosensor and the circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photosensor, and particularly to a contact type line sensor that can be used in facsimiles, OCR league document reading units, and the like.

[Conventional technology]

FIG. 5 is a perspective view showing the general configuration of a long line sensor (
(Referring to Japanese Unexamined Patent Publication No. 58-172057), No. 6
The figure is Oplus E No, 56. It is a block diagram drawn based on the conventional long line sensor shown in page 51.

In FIG. 5, a light source 4. A lens array 3 is arranged close to each other, and a photoelectric conversion element array 2 is mounted on the base l of the long line sensor so as to face the end face of the lens array 3. Note that arrow 7
indicates the main scanning direction.

In FIG. 6, reference numeral 10 denotes a blocking type photoelectric conversion element arranged in large numbers in a line. Note that the blocking type here refers to one in which carriers from the outside cannot flow into the device, but carriers inside the device can flow out to the outside. Further, reference numeral 11 serves as a lower lead-out electrode and wiring of this photoelectric conversion element 10, and this wiring 11 is connected to a driving LSI (scanning control circuit) 12. In addition, this photoelectric conversion element 1
0 is also connected to the readout circuit. This wiring 11 is
One LS112a and one LS112a are alternately distributed on the left and right sides of the photoelectric conversion element array 2, respectively.
2b. 13 is the photoelectric conversion element 1
It is an amorphous semiconductor that generates carriers due to light. 14 and 15 are also elements of the photoelectric conversion element 10, 14 is a transparent electrode, and 15 is a common electrode that supplements the sheet resistance of this transparent electrode 14 and also serves as a window of the light receiving section.

FIG. 7 is an equivalent circuit diagram of FIG. 6. 13゛ is a photodiode, 13'' is this photodiode 1
It represents the equal amount of alcoholic drinkers that occurs when a reverse bias is applied to 3'. Lower electrode 11 of photodiode 13'
Cr is used as the amorphous semiconductor 13, and non-doped amorphous silicon is used as the amorphous semiconductor 13.

When Indium Tin Oxide (rT O) containing In as the main component is used as the transparent electrode 14, which is the upper electrode, the ITO/non-doped amorphous silicon junction exhibits stronger diode characteristics than the Cr/amorphous silicon junction. It becomes a diode, and its forward direction is from the ITO to the non-doped amorphous silicon. Each photodiode 13a'
, 13b', -, 13n' are common electrodes 1
5 to the negative pole of the power source 27. Further, scanning switches 22a and 2 are connected to the cathodes, respectively.
2b, . . . , 22n are provided, and these are connected to the output terminal 26 via respective switches 22a to 22n.

Further, a load resistor 23 is connected between this output terminal 26 and ground.

Next, the operation will be explained. When the switch 22a is turned on, the amount of alcoholic beverages 132'' is charged through the load resistor 23 to the voltage of the power supply 27.Next, when the switch 22a is turned off and the switch 22b is turned on, the amount of alcoholic beverages 132'' is charged to the voltage of the power supply 27 in the same way.
`` is charged. Thereafter, by sequentially scanning the switches 22, all the equal amount of alcoholic beverages 13'' are charged.

In FIG. 5, the light from the light source 4 is strongly and weakly reflected by the black and white of the original 5 on the line of the original 5 located at the bottom of the lens array 3, and is guided by the lens array 3 to the photoelectric conversion element 10a. Amount 13b", 13c",...
, 13n'', the electric charge of the first photodiode (f13a'') decreases by the amount of carrier charge generated in the photodiode 132'' by this light, and as a result, this optical signal charge becomes the photodiode 113a''. The amount of light signal charge is almost proportional to the amount of light incident on the photoelectric conversion element 10a.Here, when the switch 22a is turned on again, the amount of alcohol 13a'' is increased by the amount of light signal charge. Current flows through the load resistor 23 for charging, and as a result, the output terminal 26
An electrical signal proportional to the amount of light incident on the photoelectric conversion element 10a is obtained. After the alcoholic drinker 113a'' is sufficiently charged, when the switch 22a is turned OFF and then the switch 22b is turned on, an electric signal proportional to the amount of light incident on the photoelectric conversion element 10b is obtained at the output terminal 26.

Thereafter, by sequentially scanning the switches 22c, . . . , 22n in the same manner, the amount of light incident on the photoelectric conversion element array 2,
That is, black and white information for the lower line of the diode array 3 of the document 5 can be read.

Note that if the photoelectric conversion elements 10 are arranged at 16 dots per 1n, the period will be 62.5 μm, and the period of the individual wirings 11 will be 125 μm.

[Problem that the invention seeks to solve]

Conventional line sensors are configured as described above, so a common electrode is required, so the photoelectric conversion section alone requires film formation four times: the lower electrode, the amorphous semiconductor, the backing electrode, and the common electrode. It is. Also, although I did not mention this here, if you try to deposit the film only three times, the individual wirings must be lined up on the same side of the photoelectric conversion element array, which shortens the distance between the wirings and lowers the yield. There was a drawback.

The present invention was made in order to eliminate the above-mentioned drawbacks of the conventional method, and provides a photosensor that can reduce the number of times of film formation while keeping the distance between wirings the same as in the prior art.

Means for Solving Problem c] The photosensor according to the present invention is one in which electrodes of a photoelectric conversion element having different polarities are connected to each other, and an extraction electrode is provided at the connection point.

[Effect]

According to this invention, different electrodes of the photoelectric conversion element are connected to each other, and the extraction electrode is drawn out from this connection point.
The extraction electrode also functions as a common electrode.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows a photosensor according to an embodiment of the present invention, and in the figure, 10 is a large number of photoelectric conversion elements arranged in a line, lla, llb, . . . are the photoelectric conversion elements 10a.
, 10b, . . . , for example, about 1 Cr
200 people, patterning was carried out using a copying plate formed into a film on the base 1.

Since the lower electrodes 11 are arranged alternately on both sides of the photoelectric conversion element array 2, when forming the photoelectric conversion elements with a pinch of 16 dots per millimeter and 125 μm, the electrodes are twice as thick as 250 μm. This lower electrode 11 may be formed at a pitch. 13, these lower electrodes 11a
. Note that this amorphous semiconductor 13 may be formed by covering the base 1 with a mask to form a film only on desired portions, or may be patterned by photolithography. 14a, 14b,... are this amorphous semiconductor 1
A film is formed and patterned on 3 to face the lower electrodes 11a, llb, . . .
, and 14b is a transparent electrode that is in electrical contact with the lower electrode 11c and the adjacent lower electrode 11 in the same manner. This transparent electrode is made of, for example, Indium Tin Oxide.
(I T Q ) is formed by about 660 or 2000 people using a sputtering device or an electron beam evaporation device, and then patterned by photolithography. The overlapping portion of the lower electrode 11 and the transparent electrode 14 becomes a photodiode, which will be described below.

FIG. 2 is an example of a circuit diagram of a photosensor using the photoelectric conversion element array 2 of the above embodiment. 13'' is a photodiode, and 13'' is the amount of alcohol generated in parallel when a reverse bias is applied to this photodiode 13''.The forward direction of this photodiode 13° is from the transparent electrode 14. The direction is toward the lower electrode 11,
The transparent electrode 14 serves as an anode, and the lower electrode 11 serves as a cathode. These diodes 13a', 13b'',...
The anodes of the adjacent diodes 13b', 13CI,
It is connected to the cathode of ..., and the whole is connected in series. However, the cathode of the diode 13a'' and the anode of the diode 13n'' at both ends are connected to the positive pole of the power supply 27 and the output terminal 26 through scanning switches 22a and 22n, respectively.The n-1 nodes between the diodes are for scanning. 2-contact switches 22b, 22c, -, 22
n-1, and these scanning switches 2
One of the contacts of 2b, .

Further, the switch 22 has a high impedance state.

Next, the operation will be explained. To make the explanation easier to understand, the wiring 30 connected to the positive terminal of the power supply 27 is the power supply wiring, the output terminal 26 and the switch 22b.

. . , 22a will be referred to as a signal wiring.

Initially, all switches 22 are set to high impedance, and switch 22a is connected to power supply wiring 30. The switch 22b is connected to the signal line 31, a reverse bias is applied to the photodiode 13a', and the equal amount of alcoholic drinker 13a'' is charged to the power supply voltage through the load resistor 23.

Next, immediately after setting the switch 22a to high impedance, the switches 22b and 22c are connected to the power supply wiring 30 and the signal wiring 31, respectively, to charge the equal amount of alcohol 13b''.Then, in the same manner, the equal amount of alcohol 13C'' is charged.

...Charge sequentially up to 113n''.

Here, in FIG. 5, the light emitted from the light source 4 is strongly and weakly reflected by the black and white of the original 5 on the line of the original fg 5 at the bottom of the lens array 3, and is guided by the lens array 3 to the photoelectric conversion element row 2. When the amorphous semiconductor 13 of the photoelectric conversion element 10 is irradiated with this light, carriers are generated, and these carriers are reverse biased by the voltage charged to the diode 13''. Therefore, the electric charge that is effectively taken out to both ends of the diode is accumulated in the equal amount 13'', and the electric charge of this equal amount 13'' is reduced by that amount.

In this way, after charging the equivalent amount of alcoholic beverages 13a'', the equivalent capacity is 13b.
While charging ",..., 13n", the amount of alcoholic beverages 13
A" has accumulated optical signal charge. Therefore, by connecting the switch 22a to the power supply wiring 30 and the switch 22b to the signal wiring 31 again, the light signal charge is charged until the amount of charge accumulated in the alcohol volume 13a" is charged. A current flows through the load resistor 23, and an electrical signal is obtained at the output terminal 26 due to this voltage drop. Thereafter, by sequentially switching the switches 22 in the same manner as in the case where the equivalent capacitance 13 was initially charged, the grayscale information for one line of the original 5 can be taken out as an electrical signal from the output terminal 26.

In the above embodiment, a simple circuit using voltage reading has been described, but current reading may be used, or other methods may be used for the reading section, such as providing a reset switch between the output terminal 26 and ground.

In addition, the lower electrodes 11 were formed so as to be distributed alternately on both sides of the photoelectric conversion element array 2, but if the number of photoelectric conversion elements per millimeter is small and the pattern shape is easy to form, the photoelectric conversion elements 11 may be formed as shown in FIG. It may be brought to one side of the conversion element array 2. In addition, in FIG. 1, since the amorphous semiconductor 13 is formed into a band shape that is easy to form, the transparent electrode 14 has a lead-out portion of 14° to connect the transparent electrode 14 and the lower electrode of the adjacent photoelectric conversion element. However, by dividing the amorphous semiconductor 13 into individual photoelectric conversion elements as shown in FIG.
It is also possible to simplify the pattern shape. Further, the amorphous semiconductor may be of a PIN type, and may be further passivated by an insulating film.

〔Effect of the invention〕

As described above, according to the photosensor according to the present invention,
Adjacent photoelectric conversion elements and electrodes with different polarities are connected to connect multiple elements in series, and the extraction electrode is drawn out from the connection point, eliminating the need for common wiring, which is necessary to form a photoelectric conversion element. This has the effect of reducing the number of times of film formation and obtaining a high yield.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a photoelectric conversion element array of a photosensor according to an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of FIG. 1, and FIGS. 3 and 4 are other embodiments of the present invention. 5 is a perspective view showing a conventional line sensor, FIG. 6 is a front view showing the configuration of FIG. 5, and FIG.
The figure is an equivalent circuit diagram of FIG. 5. DESCRIPTION OF SYMBOLS 1... Base, 2... Photoelectric conversion element row, 3... Lens array, 4... Light source, 5... Document, 6... Sub-scanning direction, 7... Main scanning direction , 10... Photoelectric conversion element, 11... Lower extraction electrode, 12... Drive LSI
(scan control circuit), 13... amorphous semiconductor, 13°
...Photodiode, 13"...etc. Alcohol consumption, 14"
- Transparent electrode, 14°... Leading out part, 22... Switch, 23... Load resistance, 26... Output terminal, 2
7...Power supply. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (4)

[Claims] (1) A photosensor comprising a plurality of blocking type photoelectric conversion elements arranged in the main scanning direction, and a scanning control and readout circuit that scans the photoelectric conversion elements to obtain a scanning output signal. Each photoelectric conversion element has electrodes with different polarities from adjacent photoelectric conversion elements connected to form a single unit as a whole.
Two photoelectric conversion element rows are formed, and extraction electrodes to be connected to the scanning control and readout circuit are drawn out from connection points between the electrodes having different polarities and terminals at both ends of the photoelectric conversion element row. Photo sensor. (2) The photosensor according to claim 1, wherein the photoelectric conversion element is a PIN type or Schottky type photodiode made of an amorphous semiconductor. (3) The photosensor according to claim 1, wherein the photoelectric conversion element has an electron and hole blocking layer at both ends of an amorphous semiconductor. (4) The photosensor according to claim 1, wherein the photoelectric conversion element is a PN type or Schottky type diode whose main component is CdS or CdSe.