JPH0576220B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sensor circuit device such as a one-dimensional image sensor that sequentially scans a plurality of photoelectric conversion elements.

[Prior art and problems to be solved by the invention] An image sensor includes multiple photoelectric conversion elements for converting optical information into electrical signals, and electrically scans the multiple photoelectric conversion elements to select an electrical signal. It also has an analog switch to obtain the desired results. The analog switch is made of a field effect transistor (FET), for example, as disclosed in Japanese Patent Application Laid-Open No. 63-2377, and is arranged near a plurality of photoelectric conversion elements.

Incidentally, in an image sensor having an integrated circuit configuration, one field effect transistor must be arranged to fit within the width of one photoelectric conversion element, that is, one pixel (for example, 125 microns).
However, it is not easy to form a field effect transistor within such an extremely narrow width. Furthermore, when three wiring conductor layers for the drain, source, and gate of a field effect transistor are provided within a predetermined width on the substrate, the width of the three wiring conductor layers inevitably becomes narrower, and the image sensor The manufacturing yield has become low. In order to solve this kind of problem, the applicant filed the patent application No. 63-
No. 190848 and Japanese Patent Application No. 1-198279, which is the application claiming domestic priority as mentioned above, proposed a scanning circuit device using a series circuit of diodes. However, details of the voltage supply method for scanning are not disclosed here.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method that can continuously scan a large number of photoelectric conversion elements at a relatively low voltage in a sensor circuit device using a diode having fewer electrodes than a transistor. It is in.

[Means for Solving the Problems] To achieve the above object, the present invention will be described with reference to the reference numerals in the drawings showing the embodiments. A plurality of first diodes Da1 each having a terminal 9, a first electrode, and a second electrode.
~Da3 is a circuit connected in series, one end of which is connected to the sawtooth wave power supply terminal 9, and a direction in which the forward current of each of the first diodes Da1 to Da3 flows based on the sawtooth wave. the respective first diodes Da1~Da
3 has and each first diode Da
A first series circuit in which the first electrodes of No. 1 to Da3 are arranged on the side of the sawtooth power supply terminal 9, and first resistors Ra1 to Ra3 and second diodes Db1 to Db3 are connected in series, respectively. It consists of a circuit connected to each first diode Da1~
The second electrode of Da3 and the common power terminal 10
and each second
a plurality of second series circuits in which each of the second diodes Db1 to Db3 has a directionality such that the forward current of the diodes Db1 to Db3 flows based on the sawtooth wave; a plurality of second resistors or capacitors Rb1 to Rb3 or Cb1 connected between the second electrodes of the diodes Da1 to Da3 and the common power supply terminal 10, respectively;
~Cb3, and a plurality of photoelectric conversion elements S1 to S3 whose one ends are connected between the first resistors Ra1 to Ra3 and the second diodes Db1 to Db3, and whose other ends are commonly connected to each other. At least first and second sensor circuit blocks B1-
B4, between the common connection side terminals of the photoelectric conversion elements S1 to S3 of the first and second sensor circuit blocks B1 to B4 and the common power supply terminal 10,
respectively connected or said first and second
The outputs of the current detection means 14 or 21 commonly connected to the sensor circuit blocks B1 to B4 and the plurality of photoelectric conversion elements S1 to S3 of the first and second sensor circuit blocks B1 to B4 are combined into one sensor circuit block B1 to B4. A common output means 7 connected to the current detection means 14 or 21 to arrange and output on the time axis
and a first sawtooth wave Va having a first section in which the voltage changes along a first slope and a second section in which the voltage changes along a second slope opposite to the first slope. a first sawtooth wave generation circuit 1 that periodically generates the voltage, a first section in which the voltage changes along the first slope, and a second section in which the voltage changes along the second slope. a second sawtooth wave with
Vb is generated periodically, and the second sawtooth wave Vb is generated such that the start time of the first section of the second sawtooth wave Vb coincides with the start time of the second section of the first sawtooth wave Vb. a second sawtooth wave generation circuit 2 configured to generate the second sawtooth wave Vb having a phase difference with respect to the first sawtooth wave Va; and the first sawtooth wave generation circuit 1.
and the first sensor circuit block B1, and is turned on in response to the first section of the first sawtooth wave Va.
and connected between the second sawtooth wave generating circuit 2 and the second sensor circuit block B2,
The present invention relates to a sensor circuit device including a second switch SW2 that is turned on in response to the first section of the second sawtooth wave Vb. Note that, as shown in claim 2, the first resistor Ra of claim 1
Replace 1 to Ra3 with capacitors C1 to C3,
In addition, the second diodes Db1 to Db3 are connected to the resistors R1 to Db3.
It can be replaced with R3.

[Operation] In the present invention, when a sawtooth wave is supplied to the circuit including the first and second diodes Da1 to Da3, Db1 to Db3, these are sequentially turned on, and the photoelectric conversion elements S1 to S3 are sequentially turned on. A voltage is applied. When the number of photoelectric conversion elements is large, the maximum amplitude of the sawtooth wave must be increased.
However, in the present invention, since a large number of photoelectric conversion elements are divided into at least first and second blocks, the maximum amplitude of the sawtooth wave can be lowered. In addition, since the start of the second section of the first sawtooth wave coincides with the start of the first section of the second sawtooth wave, scanning with good continuity is possible regardless of the existence of the second section. Become.

[Example] Next, a sensor circuit device (one-dimensional image sensor) according to an example of the present invention will be described with reference to FIGS. 1 to 5.

The image sensor in FIG. 1 includes first, second, third and fourth sensor circuit blocks B1, B2, B3,
It has B4. In FIG. 1, only four sensor circuit blocks B1 to B4 are shown for convenience of illustration, but in reality, many more sensor circuit blocks are included.

first and second sawtooth wave generation circuits 1 for driving the plurality of sensor circuit blocks B1 to B4;
2 generates the first and second sawtooth waves shown in FIGS. 4A and 4B under the control of a timing signal given from a timing signal generating circuit 3. The first sawtooth wave (triangular wave) in FIG. 4A has a first section T1 that generates a ramp voltage with a positive slope and a second section T2 that generates a ramp voltage that has a negative slope, It occurs repeatedly at regular intervals. The second sawtooth wave (triangular wave) Vb has the same waveform as the first sawtooth wave Va, having a first section T1 and a second section T2, but with respect to the first sawtooth wave Va, T1 has a phase difference of That is, the phase difference is such that the start point of the first section T1 of the second sawtooth wave Vb coincides with the end point of the first section T1 of the first sawtooth wave Va, that is, the start point of the second section T2. has.

The first sawtooth wave generating circuit 1 is connected to the odd-numbered first wave generator through the first and third switches SW1 and SW3.
and a third sensor circuit block B1, B3. The second sawtooth wave generating circuit 2
and even-numbered second and fourth sensor circuit blocks B2,
Connected to B4.

First, second, third and fourth switches SW1~
SW4 is an analog switch consisting of an electronic switch, which is controlled by a switch control circuit 4 consisting of a shift register and is turned on sequentially as shown in FIG. 4C, E, G, and I. As a result, the sensor circuit blocks B1 to B4 are sequentially driven regardless of the existence of the second section T2 of the negative slope of the sawtooth wave. The output lines 5a, 5b, 5c, 5d of each sensor circuit block B1 to B4 are shown in FIG.
The switches 6a, 6 are turned on as shown in J.
They are commonly connected via pins b, 6c, and 6d.
Therefore, the sensor output can be continuously obtained at the sensor output terminal 7 as shown in principle in FIG. 4G. Incidentally, each of the sensor circuit blocks B1 to B4 sends out an output signal in synchronization with the sample hold signal Vs and the discharge control signal Vr given from the switch control circuit 4.

Each of the sensor circuit blocks B1 to B4 in FIG. 1 is constructed as shown in FIG. Although only the first sensor circuit block B1 is shown in FIG. 2, the other sensor circuit blocks B1 to B4 have the same construction. The sensor circuit block includes a sawtooth wave power supply terminal 9 connected to the sawtooth wave generation circuit 1 via a switch SW1, a common power supply terminal 10 connected to the ground, and four unit circuits corresponding to four pixels, that is, bits. K0, K1, K
2, K3, an integrating circuit 11, and a sample hold circuit 12. One sensor circuit block B1 of this one-dimensional image sensor is configured to be able to detect more than four pixels. However, since it is difficult to show all the unit circuits corresponding to all pixels in the drawing, only a part of them is shown in FIG.

Three mutually identical unit circuits K1, K2, K3
are first diodes Da1, Da2, Da3, second diodes Db1, Db2, Db3, first resistors Ra1, Ra2, Ra3, and second resistors Rb1, Rb.
2, Rb3, photoelectric conversion elements S1, S2, S3 as circuit elements to be scanned, and blocking diodes Dc1, Dc2, Dc3. Another unit circuit K0 includes a second diode Db0,
It consists of a first resistor Ra0, a photoelectric conversion element S0, and a blocking diode Dc0. The unit circuit K0 includes the first diodes Da1, Da2, Da3 and the second diodes in other unit circuits K1, K2, K3.
It does not have anything corresponding to the resistors Rb1, Rb2, and Rb3. However, the unit circuit K0 can also be connected with those corresponding to the first diode and second resistor of other unit circuits K1, K2, and K3. Furthermore, the first stage unit circuit K0 can be omitted from the image sensor shown in FIG. 2 if necessary.

three first diodes Da1 having an anode (first electrode) and a cathode (second electrode);
One end (left end) of a circuit in which Da2 and Da3 are connected in series (first series circuit) is connected to a sawtooth wave power supply terminal 9. First diode Da
1, Da2, and Da3 have directionality that is biased in the forward direction by the sawtooth voltage. That is,
The anodes of the first diodes Da1 to Da3 (the first
electrode) is arranged on the side of the sawtooth wave power supply terminal 9. Note that when a negative sawtooth wave is applied to the sawtooth wave power terminal 9, the cathodes of the first diodes Da1 to Da3 are arranged on the sawtooth wave power terminal 9 side.

First resistors Ra1, Ra2, Ra3 and second diodes Db1, Db2, Db3 are connected between the cathodes (second electrodes) of the first diodes Da1, Da2, Da3 and the common power terminal 10, that is, the ground. Circuits connected in series (second series circuits) are respectively connected. In the unit circuit K0, 2
A series circuit of a first resistor Ra0 and a second diode Db0 is connected between the two power supply terminals 9 and 10. Second diode Db0, Db1, Db2,
Db3 has directionality that is forward biased by a sawtooth wave.

A photoelectric conversion element S0 is connected to the interconnection point P0, P1, P2, P3 between the first resistor Ra0, Ra1, Ra2, Ra3 and the second diode Db0, Db1, Db2, Db3 in each unit circuit K0, K1, K2, K3. ，
The cathodes of S1, S2, and S3 are connected to each other. The anodes of the photoelectric conversion elements S0, S1, S2, and S3 are blocking diodes Dc0 and Dc to prevent mutual interference among the photoelectric conversion elements S0 to S3.
1, Dc2, and Dc3, and is connected to the common power supply terminal 1 via an integrating capacitor 14 that functions as a common current detection element of the common integrating circuit 11.
Connected to 0. Therefore, each photoelectric conversion element S
0 to S3 are substantially connected in parallel to each second diode Db0 to Db3. Photoelectric conversion element S0,
S1, S2, and S3 are composed of photodiodes, and are connected so as to be reverse biased by the voltage of the voltage source 1. Since the photoelectric conversion elements S0 to S3 operate with a reverse bias voltage, the current flowing therein is extremely small.

Details of each part of the image sensor shown in FIG. 2 are as follows.

The sawtooth wave supplied between the sawtooth power terminal 9 and the common power supply terminal 10 has a maximum amplitude value that can turn on all the diodes Da1 to Da3, Db0 to Db3, and It has a ramp voltage region (first section) that rises at a slower speed than the rise speed of the two diodes Da1 to Da3 and Db0 to Db3.

Photoelectric conversion elements S0 to S3, first diode
Da1 to Da3, second diode Db0 to Db3,
The blocking diodes Dc0 to Dc3 are pin junction diodes, and each includes a hydrogenated amorphous silicon semiconductor layer, one electrode layer provided below this semiconductor layer, and one electrode layer provided above the semiconductor layer. and the other electrode layer, and are provided on a common insulating substrate (not shown). The width given to each unit circuit K0 to K3 formed by an integrated circuit is
In the case of 125μ (microns), the first and second
The width of the wiring conductor layer of the diodes Da1 to Da3 and Db0 to Db3 can be set to about 20 μ (microns). If a field effect transistor is used for scanning the photoelectric conversion elements S0 to S3,
The width of the wiring conductor layer is approximately 10 μm (microns), which is narrower than that in this embodiment, resulting in a poor manufacturing yield of the image sensor.

Since the photoelectric conversion elements S0 to S3 are reverse biased, they are equivalently represented by a parallel circuit of a capacitance Cs shown in FIG. 3 and a current source Is proportional to the light intensity. Note that the value of the current flowing through the equivalent capacitance Cs of the photoelectric conversion elements S0 to S3 is extremely small.

When the first diodes Da1 to Da3 and the second diodes Db0 to Db3 are turned on, the voltage across them, that is, the forward voltage Vf is approximately 1V. The first resistors Ra0 to Ra3 are each 100kΩ, and the second
The resistances Rb1 to Rb3 are each 1 kΩ, and are made of a material such as TiO ₂ , Ta-SiO ₂ or NiCr.

The integration circuit 11 is a circuit that detects changes in the photoelectric conversion elements S0 to S3, and includes a current detection/integration capacitor 14 and a discharge (reset) switch 1.
5 and an amplifier 16. Since the capacitor 14 is connected between the anodes of the photoelectric conversion elements S0 to S3 and the ground, the capacitor 14 is connected between the anodes of the photoelectric conversion elements S0 to S3 and the ground.
It is charged by the current flowing through S3. A switch 15 connected in parallel to the capacitor 14 is turned on at or near the time when each photoelectric conversion element S0 to S3 finishes charging the capacitor 14 in order to separate and detect the output currents of the photoelectric conversion elements S0 to S3. This causes the capacitor 14 to be in a discharged state. One end of the capacitor 14 is connected to the sample and hold circuit 12 via an amplifier 16. Therefore, the sample and hold circuit 12 is similar to the integration circuit 1.
The output voltage of 1 is sampled immediately before the discharge switch 15 starts to be turned on and held.

The switch control circuit 4 connected to the timing signal generation circuit 3 in FIG.
A signal for controlling SW4 and switches 6a to 6d, a sample hold control signal Vs shown in FIG. 5f, and a discharge control signal Vr shown in FIG. 5g are generated. The sample and hold control signal Vs in FIG. 5F rises in synchronization with the leading edge of the square wave timing pulse Vt in FIG. 5E and lasts for a certain period of time. The discharge control signal Vr in FIG. 5G rises a little later than the leading edge of the sample-and-hold control signal in FIG. 5F, and falls after a relatively short period of time.

[Operation] When the sawtooth slope voltage supplied to the sensor circuit block of FIG. 2 gradually increases, the potential Vp0 at point P0 gradually increases as shown in FIG. 5B.
As a result, the potential Vp0 at point P0 changes to the unit circuit K
The forward voltage Vf of the second diode Db0 (approximately
1V), diode Db0 turns on, and the potential Vp0 at point P0 remains at a nearly constant value (approximately Vf).
That is, it becomes the saturation voltage value. Almost at the same time as the second diode Db0 of the unit circuit K0 is turned on, the first diode Da1 of the unit circuit K1 is also turned on. First diode of unit circuit K1
During the period when Da1 is non-conducting (off state), the cathode of the first diode Da1 is approximately zero volts, but when the first diode Da1 becomes on state and the sawtooth voltage Vd further increases, the first diode Da1 The cathode voltage of the diode Da1 increases following the sawtooth voltage Vd. That is, when the first diode Da1 is turned on, the voltage across it is almost fixed to the forward voltage Vf, so the voltage obtained by subtracting the forward voltage Vf of the diode Da1 from the sawtooth voltage Vd is applied across the resistor Rb1. join. Furthermore, during the period when the second diode Db1 of the unit circuit K1 is non-conducting, the potential at the point P1 is the same as the second resistor Rb.
It becomes almost equal to the voltage across both ends of 1. Therefore, after the first diode Da1 is turned on, the point P
1's potential Vp1 gradually rises as shown in FIG. 5B. The potential Vp1 at point P1 is the second diode
When the forward voltage Vf of Db1 is reached, this turns on, and the potential Vp1 at point P1 becomes a substantially constant value Vf. Almost at the same time as the second diode Db1 of the unit circuit K1 turns on, the first diode Db1 of the unit circuit K2 turns on.
diode Da2 turns on, and the point P2
Then, a potential Vp2 is obtained as shown in FIG. 5B.
When the sawtooth voltage increases further, the unit circuit K3
The first diode Da3 of turns on state,
The potential Vp3 shown in FIG. 5B is obtained at the point P3. Point P
When the potentials Vp0 to Vp3 of 0 to P3 change sequentially as shown in FIG. 5B, the photoelectric conversion elements S0 to S3 connected between each point P0 to P3 and the ground through the capacitor 14 driven by That is, the photoelectric conversion elements S0 to S3 are electrically scanned.

In the circuit of FIG. 2, photoelectric conversion elements S0 to S3
are arranged one-dimensionally. When reading optical information with the photoelectric conversion elements S0 to S3, first, a sawtooth wave having the maximum amplitude that can turn on all of the first diodes Da1 to Da3 and the second diodes Db0 to Db3 is applied to the power supply terminal. 9,
Give for 10 minutes. Note that the first diode Da1
~Da3 and all of the second diodes Db0 to Db3 may be applied by an independent circuit other than a sawtooth waveform.

During the period when all of the first diodes Da1 to Da3 and the second diodes Db0 to Db3 are in the on state, the second diode obtained at the points P0 to P3
Each photoelectric conversion element S0 to S3 is reverse biased by the forward voltage Vf (approximately 1V) of Db0 to Db3, and the third
A capacitance Cs, equivalently shown in the figure, is charged. Note that, since the equivalent capacitance Cs is extremely small, charging of the equivalent capacitance Cs can be achieved by the current in the region before the point where the forward current of the blocking diodes Dc0 to Dc3 rises sharply.

An optical signal obtained from an object (not shown), such as a facsimile document, which is placed opposite to the image sensor in FIG.
When input to S3, the amount of charge charged in the equivalent capacitance Cs of the photoelectric conversion elements S0 to S3 changes depending on the presence or absence and magnitude of the optical signal. That is, among the photoelectric conversion elements S0 to S3, a discharge of equivalent capacitance Cs occurs in those to which an optical signal is input, and a discharge of equivalent capacitance Cs does not occur in those to which no optical signal is input. equivalent capacitance Cs
The amount of discharge varies depending on the amount of light. There are two methods for providing optical input to the photoelectric conversion elements S0 to S3. One method is to always provide optical input to the photoelectric conversion elements S0 to S3, and the other is to provide optical input only during a predetermined period (for example, a period when the sawtooth wave voltage Vd is 0 volts). .

When the sawtooth voltage Vd increases linearly with time as shown in FIG. 5A, potentials Vp0, Vp1, Vp2, Vp2,
Vp3 is obtained, which makes the photoelectric conversion element S0
~S3 are sequentially reverse biased. In other words,
A voltage for charging the equivalent capacitance Cs shown in FIG. 3 is applied to the photoelectric conversion elements S0 to S3. At this time, a charging current flows to those of the equivalent capacitance Cs of the photoelectric conversion elements S0 to S3 that are discharged due to optical input, but a charging current flows to those that are not discharged due to no optical input. do not have.
Equivalent capacitance of photoelectric conversion elements S0 to S3
The charging current of Cs is from blocking diode Dc0 to
Since it flows through Dc3 and capacitor 14,
The voltage of the capacitor 14 is the voltage of the photoelectric conversion elements S0 to S3.
The equivalent capacitance Cs changes depending on the presence or absence of charging current. In FIG. 5C, a photoelectric conversion element S0
The current Iout of the common output line of ~S3 is shown. In addition, in this FIG. 5C, there is a large optical input to the three photoelectric conversion elements S0, S1, and S3,
The current Iout of the common line when a small optical input is applied to one photoelectric conversion element S2 is shown. The current Iout is the potential Vp0 to Vp at each point P0 to P3
3, and decreases as the potentials Vp0 to Vp3 approach saturation.

The capacitor 14 of the integrating circuit 11 is charged with the current Iout shown in FIG. 5C, and this charging voltage Vc changes as shown in FIG. 5D. Photoelectric conversion element S0~S
In order to detect the three current changes separately, the discharge switch 15 is periodically turned on. The sample-and-hold circuit 12 samples the integral output voltage Vc shown in FIG. 5D in synchronization with the trailing edge of the pulse showing the sample-and-hold control signal Vs shown in FIG. Keep only the width of . Output voltage of sample hold circuit 12
Vout is the photoelectric conversion element S0 as shown in FIG. 5H.
- Corresponds to the optical input of S3.

The first to fourth sensor circuit blocks B1 in FIG.
~B4 are t0~t1, t1~t2, t2~t3, t in FIG. 4 based on the sawtooth wave voltages Va, Vb.
Scanning is performed sequentially in the period from 3 to t4. Since each scanning period is continuous, a large number of photoelectric conversion elements S0 to S0 are arranged one-dimensionally at the output terminal 7 in FIG.
The output of S3 is obtained continuously.

[Modifications] The present invention is not limited to the above-described embodiments, and, for example, the following modifications are possible.

(1) As shown in FIG. 6, a sawtooth wave that changes stepwise may be generated from the sawtooth wave generation circuits 1 and 2. In this case, the height of the stairs (the voltage between the steps) may be increased as the stairs become higher. In this way, the photoelectric conversion elements S0~
It is possible to prevent the interval between the outputs of S3 from increasing as the stage progresses.

(2) The sawtooth wave can be made into a waveform having a quadratic slope as shown in FIG.

(3) Provide three or more sawtooth wave generation circuits, give three or more sawtooth waves obtained from these circuits a phase difference as shown in Fig. 4, and distribute these to the sensor circuit blocks B1 to B4. You can do it like this.

(4) As shown in FIG. 8, the capacitor 14 as the current detection means in FIG.
It can be replaced with 1. The current-voltage conversion circuit 21 includes an operational amplifier 21a and a resistor 21b. The inverting input terminal of the operational amplifier 21a is the second
It is connected to the common output line in the figure, and its non-inverting input terminal is connected to ground. Output terminal Iout
flows through the resistor 21b, and the inverting input terminal becomes ground level due to the imagina- tion, so that a voltage corresponding to the current is obtained at the output terminal. Note that the diode 20 forms a path in the opposite direction. Further, the current detection means is not limited to the capacitor 14 or the current-voltage conversion circuit 21 for current detection, but may be configured by connecting a resistor to the capacitor 14, for example. The integrating circuit 11a includes an input resistor 22, an operational amplifier 23, an integrating capacitor 24 connected between an input terminal and an output terminal of the operational amplifier 23, and a capacitor 24.
and a discharge switch 15a connected in parallel to the discharge switch 15a. Even if the current detection section and the integration section are separated in this way, the same effects as in the embodiment can be obtained.

(5) As shown in Figure 9, the second resistor Rb in Figure 2
1 to Rb3 can be replaced with capacitors Cb1 to Cb3. In addition, capacitors Cb1 to Cb
Replace 3 with a reverse biased diode,
The capacitance of this diode may be used.

(6) As shown in Figure 10, the first resistor in Figure 2
Replace Ra1 to Ra3 with capacitors C1 to C3, and replace second diodes Db1 to Db3 with resistor R1.
~R3. Note that the capacitance of the capacitors C1 to C3 is the same as that of the photoelectric conversion elements S1 to C3.
Make it sufficiently larger than the equivalent capacity of S3. Alternatively, the capacitors C1 to C3 may be replaced with diodes connected to reverse bias polarity, and the capacitances of these diodes may be used as capacitors.

(7) connecting blocking diodes Dc0 to Dc3 in series to the first resistors Ra1 to Ra3 to prevent mutual interference of the photoelectric conversion elements S0 to S3;
or second resistors Rb1 to Rb3 and first resistor Ra1
~Ra3.

(8) The photoelectric conversion elements S0 to S3 can be made into photoconductive elements whose resistance value changes with optical input.

(9) The polarity of each diode and the polarity of the sawtooth wave can be reversed.

(10) Instead of independently providing a current detection means such as an integrating circuit 11 and a sample hold circuit 12 in each sensor circuit block B1 to B4, these may be provided in common to each sensor circuit block B1 to B4. good. That is, a common current detection means may be connected to the output terminal 7 in FIG.

[Effects of the Invention] As described above, according to the present invention, it is possible to continuously scan a large number of photoelectric conversion elements with a low voltage.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an image sensor according to an embodiment of the present invention, Fig. 2 is a circuit diagram showing the sensor circuit block of Fig. 1 in detail, and Fig. 3 is an equivalent circuit diagram of the photoelectric conversion element of Fig. 2. , Fig. 4 is a waveform diagram showing the state of each part in Fig. 1 in principle, and Fig. 5 is a waveform diagram showing the state of each part in Fig. 2.
6 and 7 are waveform diagrams showing the sawtooth waveform of the modified example. FIG. 8 is a circuit diagram showing the integral circuit of the modified example.
The figures are circuit diagrams showing sensor circuit blocks of modified examples. 1...First sawtooth wave generation circuit, 2...Second
Sawtooth wave generation circuit, B1 to B4...Sensor circuit block, SW1 to SW4...Switch, S0
~S3...Photoelectric conversion element, Da1~Da3...1st
diodes, Db0 to Db3...second diodes.

Claims (1)

[Claims] 1 [1] A common power terminal 10, a sawtooth wave power terminal 9 for applying a sawtooth wave, and a plurality of first diodes each having a first electrode and a second electrode. A circuit in which Da1 to Da3 are connected in series, one end of which is connected to the sawtooth wave power supply terminal 9, and the forward current of each first diode Da1 to Da3 flows based on the sawtooth wave. Each of the first diodes Da1 to Da3 has a directionality, and each of the first diodes Da1 has a directionality.
A first series circuit in which the first electrode of ~Da3 is placed on the side of the sawtooth power supply terminal 9, each of which has a first resistor Ra1~Ra3 and a second diode Db1~Db3 in series. consisting of a connected circuit, each first diode Da
connected between the second electrodes Db1 to Db3 and the common power supply terminal 10, respectively, and have a directionality such that the forward current of each of the second diodes Db1 to Db3 flows based on the sawtooth wave. Each second diode Db1~Db
3 has a plurality of second series circuits, and a plurality of second resistors each connected between the second electrode of each of the first diodes Da1 to Da3 and the common power supply terminal 10. or capacitors Rb1 to Rb3 or Cb1 to Cb3, and a plurality of photovoltaic devices whose one ends are connected between the first resistors Ra1 to Ra3 and the second diodes Db1 to Db3, and whose other ends are commonly connected to each other. at least first and second sensor circuit blocks B1 to B4 each having conversion elements S1 to S3; and the first and second sensor circuit blocks B1.
~B4 between the common connection side terminal of the photoelectric conversion elements S1 to S3 and the common power supply terminal 10,
Current detection means 14 or 21 connected respectively or in common to the first and second sensor circuit blocks B1 to B4;
and the first and second sensor circuit blocks B1
A common output means 7 connected to the current detection means 14 or 21 for arranging and outputting the outputs of the plurality of photoelectric conversion elements S1 to S3 of ~B4 on one time axis; A first sawtooth wave Va that periodically generates a first sawtooth wave Va having a first section in which the voltage changes along a slope and a second section in which the voltage changes along a second slope opposite to the first slope. 1 sawtooth wave generating circuit 1; and a first sawtooth wave generating circuit 1 whose voltage changes along the first slope.
and a second section in which the voltage changes along the second slope. the first sawtooth wave such that the starting point coincides with the starting point of the second section of the first sawtooth wave;
A second sawtooth wave Vb that is set to have a phase difference with respect to Va and generate the second sawtooth wave Vb.
a sawtooth wave generation circuit 2; the first sawtooth wave generation circuit 1 and the first sawtooth wave generation circuit 2;
connected between the sensor circuit block B1 of
a first switch SW1 that is turned on corresponding to the first section of the first sawtooth wave Va; the second sawtooth wave generation circuit 2;
connected between the sensor circuit block B2 of
and a second switch SW2 that is turned on in response to the first section of the second sawtooth wave Vb. [2] A plurality of first diodes Da1 to Da3 each having a common power terminal 10, a sawtooth wave power terminal 9 for applying a sawtooth wave, and a first electrode and a second electrode are connected in series. One end of the circuit is connected to the sawtooth wave power supply terminal 9, and the directionality is such that the forward current of each of the first diodes Da1 to Da3 flows based on the sawtooth wave. diodes Da1 to Da3 have, and each first diode Da1
A first series circuit in which the first electrode of ~Da3 is placed on the side of the sawtooth power supply terminal 9, and a circuit in which capacitors C1 to C3 and first resistors R1 to R3 are connected in series, respectively. , each of the first diodes Da1 to Da3
a plurality of second series circuits each connected between the second electrode of each of the first diodes Da1 to Da3 and the common power terminal 10; a plurality of second resistors Rb1 each connected between
~Rb3, one end of which connects the capacitors C1 to C3 and the first
at least a first
and second sensor circuit blocks B1 to B4; and the first and second sensor circuit blocks B1.
~B4 between the common connection side terminal of the photoelectric conversion elements S1 to S3 and the common power supply terminal 10,
Current detection means 14 or 21 connected respectively or in common to the first and second sensor circuit blocks B1 to B4;
and the first and second sensor circuit blocks B1
A common output means 7 connected to the current detection means 14 or 21 for arranging and outputting the outputs of the plurality of photoelectric conversion elements S1 to S3 of ~B4 on one time axis; A first section that periodically generates a first sawtooth wave Va having a first section in which the voltage varies along a slope and a second section in which the voltage changes along a second slope opposite to the first slope. a sawtooth wave generating circuit 1; a first sawtooth wave generating circuit whose voltage changes along the first slope;
and a second section in which the voltage changes along the second slope.
is generated periodically, and the second sawtooth wave Vb is generated such that the start time of the first section of the second sawtooth wave Vb coincides with the start time of the second section of the first sawtooth wave Vb. 1 sawtooth wave
A second sawtooth wave Vb that is set to have a phase difference with respect to Va and generate the second sawtooth wave Vb.
a sawtooth wave generation circuit 2; the first sawtooth wave generation circuit 1 and the first sawtooth wave generation circuit 2;
connected between the sensor circuit block B1 of
a first switch SW1 that is turned on corresponding to the first section of the first sawtooth wave Va; the second sawtooth wave generation circuit 2;
connected between the sensor circuit block B2 of
and a second switch SW2 that is turned on in response to the first section of the second sawtooth wave Vb.