JPS5827028A - Photoelectric converter - Google Patents

Abstract

PURPOSE:To facilitate correction of a photoelectric property, by mounting a voltage generating circuit, which outputs a set output, in order, to photoelectric elements one-dimentionally arranged, and a switching circuit for applying to the corresponding to photoelectric element and a series resistance. CONSTITUTION:A scanning address generating part 6 divides an output of a master clock generating circuit 5 to output address signals (a) and (b). Correction data d on unevenness against photoelectric elements A1-Amn are written in a memory circuit 7, and the data b are read by means of the signal (a) and (b). The data d, D/A-converted (8) through the working of a siwtch 11, and a voltage of a constant-voltage source 9 are applied to an amplifier 10, and an output is connected to an image sensor 1 via transistors (TR) F1-Fm. Output terminals of the sensor 1 are coupled to one end of a resistance Rc via TR G1-Gn, and a photoelectric onverting signal K is outputted from an amplifier 2. the TR F1- Fm and G1-Gn are regulated by output decoders 12 and 13, and the corrected signal K can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photoelectric conversion device having a plurality of photoconductive elements such as CDS arranged in a -dimensional array.

FIG. 1 shows the basic configuration of this type of photoelectric conversion device.

Reference numeral 1 denotes an image sensor, which includes N photoconductive elements A1 to AH arranged in one row.

The photoconductive elements A1 to AN have resistors R1 to R, respectively.
N are connected in series, and the connection points between each of the photoconductive elements A1 to AN and the resistors R1 to RN are connected to switches 81 to 81, respectively.
It is connected to the input of amplifier 2 via SN.

Then, when a common constant voltage is applied from the constant voltage power supply 3 to each of the photoconductive elements A1 to AN and the resistors R1 to RN, the resistance value of the photoconductive elements A1 to AN changes depending on the amount of light incident on them, so each light Conductive elements A1 to AN and resistor R1
The voltage at the connection point with ~RN has a value that corresponds to the amount of light incident on each photoconductive element A1 to AN.

Therefore, by sequentially and selectively turning on the switches 81 to SN, a time-series electric signal corresponding to the pattern of light incident on the photoconductive elements A1 to AN can be obtained from the output of the amplifier 2317.

However, in an actual photoelectric conversion device of this type, the total number N of photoconductive elements is as high as 1000 to 2000, so the first
Since it is impossible to provide switches 81 to SN made of transistors or the like for each photoconductive element A1 to AN as in the circuit shown in the figure, it is impossible in terms of implementation. The circuit configuration was as follows.

That is, in FIG. 2, 1 is an image sensor, which has m x n photoconductive elements A1 to Amn and diodes D1 to Dmn connected in series to these photoconductive elements A1 to 80, respectively. It will be done. The photoconductive element A
1 to Amn, where n photoconductive elements constitute one block, and m
It is divided into blocks.

One end of the photoconductive elements A1 to Amn is a diode D1.
.about.Drnn are collectively connected to the common side terminals t1 to tm for each block.

Further, the other ends of the photoconductive elements A1 to Amn are grouped together for each corresponding position in the block and connected to individual side output terminals P1 to Pn.

The common side terminals 11 to tm are each connected to a switch Sa1.
~San and the ten poles of the constant voltage power supply 3 via the resistor R. One pole of this constant voltage power supply 3 is grounded. Further, resistors Ra1 to Ram are connected between the common side terminals t1 to tm and the ground. The separate side output terminals P1 to Pn are switches Sb1 to Sbn, respectively.
is connected to the input of amplifier 2 via a resistor R
It is grounded via b1 to Rbn.

In this conventional device, as shown in the timing chart of FIG. 3, by sequentially turning on the switches sa1 to sam, a constant voltage is applied to the photoconductive elements A1 to Amn in each block from the constant voltage power source 3. Ru. Then, as mentioned above, each time the switches sa1 to san are turned on, the switches sb1 to Sbn are turned on sequentially, and the output voltage of the photoconductive element A1 of the first block is are sequentially input to the amplifier 2 via the individual side output terminal P1 and the switch sb1, and then the output voltages of the second photoconductive elements An+1 to A2n are input to the individual side output terminal P2 and the switch Sb2. sequentially through amplifier 2
The same operation is performed for the remaining blocks.

As a result, a time-series electric signal k (hereinafter referred to as a photoelectric conversion signal) corresponding to the pattern of light incident on each of the photoconductive elements A1 to Amn can be obtained from the photoelectric conversion signal output terminal 4.

However, there are variations in the photoconductive properties of each of the photoconductive elements A1 to Amn, and if this variation is not corrected, variations will occur in the reference level of each pit in the photoelectric conversion signal obtained from the photoelectric conversion signal output terminal 4. It ends up.

Therefore, in the conventional device shown in FIG. 2, due to the manufacturing process of the photoconductive element array, the variations between the photoconductive elements A1 to Amn that are located close to each other are smaller than the variations between the elements that are located far from each other. The above correction was performed for each block by taking advantage of the small size. That is, the resistance R
By adjusting the values of a1 to Ram and changing the ratio at which the voltage E of the power source 3 is divided by the resistor R and Ra1 to Ram, the average output of the photoconductive elements in each block is made the same. The above correction was made.

In FIG. 3, kl is each photoconductive element A1 to Amn
A uniform amount of light is incident on the resistor Ra1=Ra2-・
. . . shows one line of the photoelectric conversion signal k when = Ratn. Further, k2 indicates the light guide conversion signal k of one line when the resistances Ra1 to Ram are adjusted and the correction is performed. As can be seen from the figure, the variation E2 in k2 is smaller than the variation El in kl.

In addition, in the above case, V is the common side terminal t1 to tn
Specifically, it is a voltage proportional to the reciprocal of the average value of the output of the photoconductive elements of each block in the case of 1.

However, with such a conventional device, not only is it impossible to compensate for variations in the characteristics of photoconductive elements within each block, but also the total number m x n of photoconductive elements is 2000 as described above. Since the number of blocks m of the photoconductive element is 607 ·, - ~100, it takes a lot of effort to adjust and set the values of the resistors Ra1 to Rafn connected to each of these blocks one by one. The drawback was that it required a lot of effort and work time, making mass production virtually impossible.

The present invention was made to eliminate the above-mentioned conventional drawbacks, and an object of the present invention is to provide a photoelectric conversion device that can extremely easily correct variations in photoconductive characteristics of each photoconductive element.

That is, the photoelectric conversion device according to the present invention includes a plurality of photoconductive elements arranged in a negative dimension, a voltage generating circuit that sequentially outputs voltages set for each of the photoconductive elements, and a voltage generating circuit that sequentially outputs voltages set for each of the photoconductive elements. a switching circuit that applies the voltage to the corresponding photoconductive element and a resistor connected in series to the photoconductive element; and application of the voltage by this switching circuit to the respective photoconductive element and the resistor. and means for temporally synthesizing the voltages generated at the connection points.

The present invention will be explained in more detail below based on the drawings.

FIG. 4 shows an embodiment of the present invention, and FIGS. 6 and 6 show timing charts in this embodiment (the opening in FIG. 6 is an enlarged view of a part of FIG. 6). In FIG. 4, numeral 1 is an image sensor, which has the same configuration as in FIG. 2. Reference numeral 6 denotes a master clock generation circuit that generates a master clock C.

Reference numeral 6 denotes a scanning address generating section consisting of a multi-stage frequency dividing circuit, which divides the clock C input from the master clock generating circuit 6 and outputs the output of each stage as address signals a and b. FIG. 5 shows an example in which the address signals a and b have binary waveforms, and the address signal A is a further frequency-divided version of the address signal a.

7 is a memory circuit consisting of a ROM, and as will be explained in detail later, heating elements A1. Each photoconductive element A is determined in advance to correct variations in the photoconductive properties of
When the correction data d for 1 to Amn is written,
This correction data d is read out using address signals a and b as address inputs.

8 inputs the correction data d read from the memory circuit 7 to D/
A D/A converter 9 is a constant voltage power supply having one pole grounded. Reference numeral 10 denotes an amplifier, the input of which is connected via a switch 11 to the output ei of the D/A converter 8 or to the ten poles of the constant voltage power supply 9.

The output of the amplifier 1o is connected to the transistors F1 to F1, respectively.
It is connected to common side terminals t1 to 'm of the image sensor via Fm. Further, the individual side output terminals b1 to bn of the image sensor 1 are each connected to one end of a common resistor R3 via transistors 01 to Gn, and the other end of this resistor R3 is grounded.

The connection point between the transistors G1 to Gn and the resistor R0 is connected to the input of an amplifier 2, and the output of this amplifier 2 is connected to a photoelectric conversion signal output terminal 4.

Reference numeral 12 denotes an m-bit parallel output decoder which receives the address signal S as input, and the m-bit outputs f1 to fffl of this decoder 12 turn on/off the transistors 81 to S.
Off is controlled respectively.

1.

Reference numeral 13 denotes an n-bit Halal output decoder which receives address signal a as input, and the n-bit outputs q1 to gn of this decoder 13 control on/off of transistors 01 to Gn, respectively.

Next, the operation of this embodiment will be explained based on the timing charts and voltage waveform diagrams shown in FIGS.

First, the constant voltage power supply 9 is connected to the input of the amplifier 10 by the changeover switch 11, and each photoconductive element A1 to
A uniform amount of light is made incident on Amn.

In this state, when address signals are sequentially inputted from the scanning address generation section 6 to the decoder 12, the outputs f1 to fn of the decoder 12 become high level (hereinafter abbreviated as "H") one by one. Accordingly, transistors F1 to Frn are sequentially turned on.

During this period, the address signal a is input from the scanning address generating section 6 to the decoder 13, and the outputs 91 to 9 of the decoder 13 are sequentially outputted from 11 to 9 each time the transistors F1 to Fo are turned on. °H# one by one, and along with this, transistor 0
1 to Gn are turned on sequentially.

As a result, with the resistor R2 connected in series, the output voltage (constant voltage) of the amplifier 10 is sequentially applied to each of the photoconductive elements A1 to Amn via the diodes D1 to Dmn. The output voltages of the photoconductive elements A1 to Amn generated by the application of the output voltage of the amplifier 1o are sequentially input to the amplifier 2, so that the output voltages from the photoelectric conversion signal output terminal 4 as shown in FIG. Time-series photoelectric conversion signals corresponding to variations in the photoconductive characteristics of each of the photoconductive elements A1 to ArQ are obtained.

In this embodiment, a value proportional to the reciprocal of the voltage value of 1 is encoded into a binary number in the photoelectric conversion signal for each photoconductive element A1 to Amn, and this is written to the corresponding address of the memory circuit 7 as correction data d. (This writing work to the memory circuit 7 is performed using a circuit jig or the like that is separate from the main circuit).

When the actual optical information is to be read by the photoconductive elements A1 to A□, the changeover switch 11 is switched.
The output e of the D/A converter 8 is connected to the input of the amplifier 1o. In this state, when address signals δ and b are input to the memory circuit 7 from the scanning address generating section 6, the same address signal a is input.

Correction data d at the address specified by b is sequentially read out from the memory circuit 7.

This sequentially read correction data d is D/A converted by the D/A converter 8, and the output e of the D/A converter 8 is amplified by the amplifier 10. Voltages having values corresponding to the correction data d for the photoconductive elements A to Amn are sequentially output.

Meanwhile, during this time, the address signal a is also sent to the decoders 12 and 13.
, b are input, so the transistor F1
~Fn and G1~Gn are sequentially turned on at the same timing as above. Therefore, the output voltages of the amplifier 1o that are sequentially outputted are different from those of the corresponding photoconductive elements A, ~Arnn.
and is applied to resistor R0. Then, the output of each of the photoconductive elements A1 to Amn at this time is amplified by the amplifier 2, so that a one-dimensional butter signal of the light incident on the photoconductive elements A1 to Amn is obtained at the output terminal 4.

Here, the outputs of the photoconductive elements A1 to Amn are output from the amplifier 1.
The output voltage of o is determined by the resistance of photoconductive elements A1 to Amn and the resistance R.
However, in this case, the output voltage of the amplifier 10 applied to each of the photoconductive elements A1 to Atnfl is not common, and the correction data d for the photoconductive elements A1 to Amn is Since the value corresponds to
The photoelectric conversion signal has been corrected for variations in photoconductive characteristics among the photoconductive elements A1 to Amn.

2 in FIG. 6 shows the photoelectric conversion signal k when the above correction is performed when a uniform amount of light is incident on each photoconductive element A, ~AmnK, and each photoconductive element A.

~The variations in Arnn's characteristics will be corrected,
The value is uniform over one line.

As described above, according to this embodiment, the photoconductive elements A1 to Amn
It is possible to completely correct variations in the characteristics of each block, but variations between photoconductive elements located close to each other are practically negligible.4 However, variations in photoconductive elements between blocks are a problem. In such a case, it is also possible to perform the above correction for each block by setting the correction data d for each block. In that case, the memory circuit 7 can be a small-capacity memory circuit that uses only the upper signal of address signals a and b.

In addition, each photoconductive element A1-A process. Even if the voltage applied to N is kept constant and the amplification factor of the amplifier 2 is sequentially changed according to the variations in the photoconductive characteristics of each of the photoconductive elements A1 to A, it is possible to correct for the variations. In this case, there arises a disadvantage of handling minute signals. However, as in the present device, each photoconductive element A1
Each photoconductive element A, ~A corresponds to the variation of ~Am n.
Such a disadvantage does not arise if the voltage applied to mn is varied.

As described above, the photoelectric conversion device according to the present invention includes a voltage generation circuit that sequentially outputs a voltage set to each photoconductive element, and a voltage generating circuit that outputs the voltage set to each photoconductive element, and a resistor connected in series to the corresponding photoconductive element. By having a switching circuit of 15, -, for applying voltage, it is necessary to adjust and set a large number of resistance values, which is troublesome as in the past, to correct for variations in the photoconductive characteristics of each photoconductive element. It is possible to obtain excellent effects such as being extremely easy to carry out without having to do so.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the basic configuration of a light guide conversion device equipped with photoconductive elements arranged in one dimension, FIG. 2 is a circuit diagram showing a conventional light conversion device, and FIG. 3 is a circuit diagram showing the conventional device. FIG. 4 is a circuit diagram showing an embodiment of the photoelectric conversion device according to the present invention, FIG. 6 is a timing chart of the embodiment, and FIG. 6A shows the photoelectric conversion signal and D/A in the embodiment. A voltage waveform diagram of the output of the converter, FIG. 6 is an enlarged view of FIG. 6A. 2...Amplifier, 4...Photoelectric conversion signal output terminal, 6...Scanning address generator, 7...
...Memory 6 circuits, 8...D/A converter, 1
o...Amplifier, 12...m-bit parallel output decoder, 13...n-bit parallel output decoder, A1~Arnn...photoconductive element, F1~ Fn, G1 to Gn...Transistor, d...Correction data, h...Photoconductive element output. Name of agent: Patent attorney Toshio Nakao and one other person. Figure 3 Figure 5 Figure 6 (in (b)

Claims (2)

[Claims] (1) A plurality of photoconductive elements arranged in − dimensions, a voltage generation circuit that sequentially outputs voltages set for each of the photoconductive elements, and the voltages sequentially output from the voltage generation circuit, A switching circuit applies voltage to the corresponding photoconductive element and a resistor connected in series to the photoconductive element, and a voltage generated at a connection point between each of the conductive elements and the resistor due to application of the voltage by this switching circuit is measured over time. 1. A photoelectric conversion device comprising a means for selectively synthesizing. (2) The voltage generation circuit includes a memory circuit in which correction data for each photoconductive element is written, and a voltage output circuit that sequentially outputs a voltage for each photoconductive element based on the data sequentially read from this memory circuit. A photoelectric conversion device according to claim 1, comprising: