JPS58131766A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To eliminate the need for a mechanical shutter by arranging an photoelectric transducer section connected to a first switching element and a second switching element connected to the transducer section, excluding charges when the second switching element is under an opened state and obtaining signal charges when the element is under a closed state. CONSTITUTION:When beams are projected to a solid-state image pickup element 1, photoelectric transduction is executed in the photoelectric transducer sections D11-Dmn, and charges corresponding to luminous energy projected to the pickup picture element are generated. Signal charges are obtained when the charges generated are stored into the sources of MOS.FETs S11-Smn, but charges generated are excluded to connecting lines connecting drains and a power supply 20 and are not stored into the sources of the S11-Smn when MOS. FETs Q11-Qmn are under opened states. When the Q11-Qmn are under closed states, on the other hand, the charges generated are stored into the sources with the exception of the case when the S11-Smn are under opened states, and signal charges are acquired. Accordingly, a shutter is closed when the Q11-Qmn are under opened states, and opened when the Q11-Qmn are under closed states in succession at the same time or selectively, and an electronic shutter is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solid-state imaging device including a solid-state imaging device in which a plurality of imaging pixels are arrayed and a scanning circuit for the imaging pixels, and particularly relates to a solid-state imaging device that obtains a still image imaging output signal. In order to eliminate the need for a mechanical shutter, a large number of imaging pixels, which are formed by a combination of a photoelectric conversion unit and a switching element, are arranged two-dimensionally in a predetermined pattern, for example, in a matrix arrangement. A solid-state imaging device having a light-receiving surface; and a scanning circuit that selectively opens a switching element of the solid-state imaging device to derive an imaging output signal based on a signal charge obtained in a photoelectric conversion section of each imaging pixel. A solid-state imaging device has been proposed that has a main component of In addition, the photoelectric conversion section may include a large number of light receiving diodes formed corresponding to each of the switching elements, or
It consists of a photoelectric conversion thin film layer formed on a one-dimensional array of switching elements.

When obtaining a still image output signal using such a solid-state imaging device, 1j1] In other words, when configuring a so-called still-tatami camera, a mechanical shutter that can be opened and closed is placed in front of the light-receiving surface of the solid-state imaging device. provided.

This mechanical 7-ray sensor is normally closed and is opened for a short time only when taking an image. When it is closed, the incident light to the light receiving surface is blocked, and only when it is open, the light receiving surface is exposed to the incident light. In response, an imaging signal based on the subject image at that time is obtained as a still image imaging output signal.

However, in conventional solid-state imaging devices equipped with such mechanical shutters, the shutter mechanism becomes complicated and expensive, and mechanical accuracy deteriorates after long-term use, reducing the reliability of the shutter. In view of the above-mentioned problems, the present invention aims to obtain a still image imaging output signal without providing a mechanical shutter. DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings, which provide a solid-state imaging device equipped with an electronic shutter function section that can perform the following functions.

FIG. 1 shows a schematic configuration of an example of a solid-state imaging device according to the present invention using an equivalent circuit. In this equivalent circuit, / is a solid-state image sensor, and this solid-state image sensor / has MO8@FET S/ as switching elements arranged in rows and columns in the horizontal direction (arrow H direction) and vertical direction (arrow V direction). /~smn
are arranged, and a photoelectric conversion unit Dzz-Dmn is connected to one end, for example, the source, of these MO8FET Sll-8mn, respectively, and further, MO8IIFET Sl/~Smn
At each connection point between the source and the photoelectric conversion unit D//~I)mn, a MoS FET as a switching element is connected
The sources of Qzl-Qmn are connected and these M
A light-receiving light is constructed by the O8 FET Szz-8mn and Qzl-Qmn and the photoelectric conversion unit D//~I)mn. Here, one of each MO8-FET Sll-8mn, one of the photoelectric conversion units Dzl-Dmn, and one of the MO8-FET Sll-8mn,
A combination with one of -FETQll-Qmn forms an imaging pixel, and its specific configuration is as shown in FIGS. 2 and 3.

FIG. 2A shows a cross section of a portion where one imaging pixel is formed in an example of a specific configuration of a solid-state imaging device. In this example, a P-type semiconductor body 2 is provided with an N-type region 3. The evening and left side are formed. A gate electrode 7 is provided across the regions 3 and 3 with an insulating layer 6 interposed therebetween.
MO8-FE, one of 8-FETSl/~Smn
TS is configured. g is a tonoin electrode of MO8-FET S. Further, a gate electrode /θ is provided across regions q and S with an insulating layer interposed therebetween. For example, in region 3
is the drain region and region q is the source region, MO
MO8-PET Q, which is one of S e F ET Q/z to Qmn, is configured. // is MO8
- It is a tonoin electrode of PET Q. Further, a photodetector diode forming a photoelectric conversion unit, which is one of the photoelectric conversion units Dll-Dmn, is configured at the P-N junction between the semiconductor substrate q and the area q. Photoelectric conversion of the light is performed. In this case, the semiconductor substrate is used while being grounded, and therefore, the example shown in FIG. sapus)l
/-) is grounded, and the anode of the light receiving diode forming the photoelectric conversion section is given a ground potential as shown in FIG. 2B.

FIG. 3A shows a cross section of a portion where one imaging pixel is formed in another example of the specific configuration of the solid-state imaging device.

In this Fl as well, an N-type region 3. 'l and S are formed, a gate electrode 7 is provided across region 3 and g via an insulating layer 6, and region 3 and g serve as a drain region and a source region, respectively.
MO8 type FET which is one of ET S//~Smn
In addition, a gate electrode 10 is provided across regions q and 5 with an insulating layer 9 interposed therebetween, and the left and da regions serve as a drain region and a source region, respectively. MO8-FE
T Q t t = MO8- which is one of Qmn
FETQ is configured. In addition to the drain electrode g of MOS-FET S provided in region 3 and the drain electrode g of MOS-FET Q provided in region S, a source electrode common to MOS-FETs S and Q is provided in region D. /2 is provided. Such MOS-FET
An insulating layer /3 is disposed on the portion where S and Q are formed, except for the source electrode, and an electrode /3 made of, for example, an aluminum layer is disposed thereon.
is connected to the source electrode /λ, and the electrode ll
A photoelectric conversion layer/S made of, for example, an amorphous silicon thin film is arranged on I, and a transparent electrode (target electrode)/B is further arranged above the photoelectric conversion layer/on the left. A portion of the photoelectric conversion layer/S that spreads over the portion where the MOS-PETs S and Q are configured forms the photoelectric conversion section Dz.
It forms a photoelectric conversion section, which is one of the 7-Dmn. That is, in this example, the photoelectric conversion unit D//~
Each of Dm and n is not formed from an independent light-receiving element such as a light-receiving diode, but is formed from a portion of the photoelectric conversion layer /S extending over the light-receiving surface. Note that the light entering the light-receiving surface is transmitted through the target electrode/B and is made incident thereon. In this case, the semiconductor substrate B is grounded, and the target electrode B is supplied with a target voltage VT, which is a predetermined DC voltage.

Therefore, the example shown in FIG. 3A in which the photoelectric conversion section is formed of a photoelectric conversion thin film layer is a MOS in terms of an equivalent circuit.
- The substrate notes of FETs S and Q are grounded, and a target voltage vT is applied to one end of the photoelectric conversion section.
The result will be as shown in FIG. 3B.

Again, in the equivalent circuit of FIG. 1, the gates of the MOS-FETs Sl/ to Smn forming each horizontal row forming each of the above-mentioned image pickup pixels are commonly connected, and / is connected to m output terminals vl-vm, respectively. In addition, the drains of the MOS/FETs Sll-8mn constituting each vertical column are commonly connected, and the MO8LIFET as a switching element is connected.
It is connected to each source of Tl to Tn, respectively. These M
Each gate of the OS"FET Ti"'-TH is connected to n output terminals h/~h of the horizontal scanning circuit/g, and each drain is commonly connected and connected through an output resistance element/9. An output terminal 2/ is connected to a power supply 20 that supplies an operating voltage vv, and is led out between a common connection point of the drains of the MOS-FETs T/ to Tn and an output resistance element /q. Note that the first vertical scanning circuit /7 supplies scanning pulses φV with sequentially different phases to its m output terminals V/~vm.
/~φvm are generated respectively, and the MOS-FET Sll-
8mn are controlled to open sequentially for each row, and the horizontal scanning circuit /g has a frequency sufficiently higher than the scanning pulse φV/~φvm at its n output terminals, -hn. , scanning pulses φh/~φhn with sequentially different phases
is generated, respectively, and control is performed to sequentially open the MOS-FETs Tt to Tn.

'Furthermore, the gates of the MO8@FETs Qll-Qmn constituting each horizontal row are also commonly connected, and the m output terminals v, /~v of the second vertical scanning circuit 2.2
m' respectively. This 20th vertical scanning circuit 2
2 controls opening/closing of MO8*FET Qll-Qmn. The dos V/ of each of the MOS-FETs Qll-Qmn are commonly connected and directly connected to the power supply 20.

Furthermore, the end of each of the photoelectric conversion units D//''=Dmn, which is opposite to the side connected to the respective sources of MO8LIFET Sll to Smn and the respective sources of MOS-FET Qll-Qmn, is , are commonly connected to lead out a terminal 23, and a predetermined potential is applied to this terminal 23. For example, photoelectric conversion units D//~I)m
When n is formed of a photodetector diode as in the example shown in FIG. 2, a ground potential is applied to the terminal Ω3, and as in the example shown in FIG. If so, a potential corresponding to a predetermined target voltage VT is applied. .

In the solid-state imaging device according to the present invention configured as described above, when light from a subject enters each imaging pixel on the light-receiving surface of the solid-state imaging device, photoelectric conversion is performed in the photoelectric conversion units Dll-Dmn. As a result, charges are generated according to the amount of light incident on each imaging pixel. This charge is MO8-FET 877~8l
A signal charge is obtained when accumulated in each source of MO8LIFET Qll-
When Qmn is in the open state, the charge generated in the photoelectric conversion unit DzA-Dmn is transferred to a direct connection path connecting each drain of MO8-FET Qll-Qmn and the power supply 20 through the MO8-FET Qlz-Qmn. Therefore, it is not accumulated in the source of MO8-FET Sll-8ln. That is, MO8・FET 977~9l
When n is in the open state, the photoelectric conversion units Dzl-Dmn
The charge obtained by is not a signal charge,
On the other hand, when MO8-FETs 917 to 9ln are in a closed state, the charges generated in the photoelectric conversion unit Dlz-Dmn are
-Except when FET Sll-8ln is in the open state,
A signal charge is accumulated in each source of MO5-FET Szl-8ln, and a signal charge corresponding to the amount of incident light is obtained in each imaging pixel7) Therefore, MO8・FET
When Qll-Qmn is in the open state, it corresponds to the shutter being in the closed state, and MO8L1FET 917
~9ln are simultaneously or selectively closed in sequence, the shutter is in the open state, and an electronic shutter is formed, so to speak. The time during which Qll-Qmn are closed simultaneously or selectively in sequence is short, and a signal is sequentially transmitted to the signal charge obtained in each imaging pixel during this short time via MO8-FET Sll-8ln. If derived, a still image imaging output signal can be obtained.

The opening/closing of MO8@FET Q/l to Qmn is controlled by the second vertical scanning circuit 22, and when capturing a still image, the second vertical scanning circuit 22 is connected to its m output terminals v. , /~vm' generate scanning signals Φl~Φm, and M
The O8-FETs Qll-Qmn are supplied to the gates of each horizontal row.

As shown in FIG. The signal Φ/ is sequentially delayed by 7 horizontal periods th of the video signal from the scanning signal Φ□1, and the scanning signal Φ/~Φm is a high V pel and MO8-FET 917~
9ln is open and MOS-FET is set at low level.
Qll-Qmn is closed, therefore MO8@F
The ETs 977 to 9ln are sequentially closed for a certain period of time Ts for each row in the horizontal direction.

Furthermore, during this still image capturing, the scanning pulses φV/ to φvm generated by the first vertical scanning circuit 7 as described above have a width of the horizontal period th of the video signal, as shown in FIG. m pulses are sequentially generated within the vertical period tv of the video signal, and each pulse corresponds to the low level of each of the scanning signals Φl to Φ□ generated by the second vertical scanning circuit 22. Furthermore, the scanning pulses φh/ to φhn, which are generated by the horizontal scanning circuit/shape as described above, are located corresponding to the terminal ends of the periods, respectively, and the scanning pulses φV and φh, as shown in FIG. It is assumed that n narrow pulses are sequentially generated within each period of / to φvm. MO8-FET 877~8ln and T, -Tn
is in the open state when each of these scanning pulses is supplied to the gate. Therefore, first, the second vertical scanning circuit 2
The low level part of the scanning signal Φl from MO8-FETQ
//~When supplied to the gate of Qln, these MO
8L1FET Ql/~Qln is in an open/closed state for a time Ts, and within this period, the photoelectric conversion unit D//~Dln
The charge obtained in MO8 FET 5 is used as a signal charge.
3 accumulated in the source of tA-8tn, and this M
At the end of the period in which O8LIFET Q/l to Qln are in the closed state, the scanning pulse φ from the first vertical scanning circuit/7
V/ is supplied to the gates of MO8-FETs Sll to Sln, MO8-F'ETSll-8ln is opened, and the signal is quickly applied to the signal charges accumulated in the respective sources to MO8-FETs Sll to Tn. 4, transmitted to the source of
Then, during the period of this scanning pulse φV/, the scanning pulse φh/~φhn from the horizontal scanning circuit /g is applied to the MO8-FET.
↑Sequentially supplied to the gates of l~Tn, MO8-F
ET 'rl-'rn are sequentially opened, and as a result, the signal current based on the signals transmitted to those sources sequentially flows through the output resistance element /wo, and as a result, Mo8 is applied to the output terminal 2/. - An imaging output signal can be easily obtained from the signal charges in the imaging pixels corresponding to the FETs Sll to Sln. Next, with a delay of /horizontal period t)1 of the video signal from the low level part of the scanning signal Φl, the low level part of the scanning signal Φ2 is supplied to the gate of Mo8. Mo8-FET
Q2/~Q2n are opened and closed for a time Ts, and during this period, the charges obtained in the photoelectric conversion units Dxl-D2n are accumulated in the sources of the Mo8-FETs S2/~S2n as signal charges. And this Mo8@FET Q2
At the end of the period when 1~Q2n are in the open state, the scanning pulse φv2 is supplied to the gates of Mo8LIFETs S2/~S2n, and these Mo5-FETs S21~S2n
is opened, and the scanning pulse φh/~φhn
The Mo8-FETs Tl-Tn are sequentially opened, and the Mo8-FETs are connected to the output terminals and 2/ in the same manner as described above.
An imaging output signal is obtained based on the signal charges in the imaging pixels corresponding to 521-82n. Thereafter, in the same manner, each of the low level portions of the scanning signals Φ3 to Φm from the second vertical scanning circuit 22 is connected to the Mo8-FET Q3t-Q3n.
is sequentially supplied to the gates of Qmz to Qmn, and the Mo8-FET is obtained by closing these gates.
Imaging output signals based on signal charges in the imaging pixels corresponding to S3/~SJn to Sm/~Smn are sequentially
An imaging output signal of /vertical period, that is, /field is obtained at output terminal 2/. In this way, the MOS
・The signal charges obtained in each imaging pixel during the period when FET Qll-Qmn is in the closed state are as follows:
Mo8@FET S/l-8mn and Mo8@FET
An imaging output signal representing a still image is obtained by being derived via Tl-Tl.

In addition, in the above, the time Ts during which each of the scanning signals Φl to Φ□ supplied by the second vertical scanning circuit 22 takes a low novelty
By changing the length of the shutter speed, the so-called shutter speed can be adjusted. A certain tVlos-FET Ql
Of course, if l-Qmn is kept in a normally closed state, an imaging output signal for a moving subject can be obtained.

As explained above, the solid-state imaging device according to the present invention does not require a mechanical shutter to obtain a still image imaging output signal, and therefore the overall structure of the device can be simplified, lightened, and downsized. , and the reliability is significantly increased.

[Brief explanation of the drawing]

FIG. 1 is an equivalent circuit diagram showing an overview of an example of a solid-state imaging device according to the present invention, and FIGS. Its equivalent circuit diagram, FIGS. 3A and B, is the EflJ shown in FIG.
A cross-sectional view and an equivalent circuit diagram showing another example of a specific configuration of a part of the solid-state imaging device 111 according to the present invention, FIG.
This is a diagram used to explain the operation of FIJ. In the figure, / is a solid-state image sensor, C is a semiconductor substrate, B and 9 are insulating layers, 7 and 10 are gate electrodes, /7 is a first vertical scanning circuit, 7g is a horizontal scanning circuit, /9 is an output resistance element, 2
/ is the output terminal, Ω) is the second vertical scanning circuit, S + 5
ll-8H1+ Q, Q//~Qmn and Tz-T
n is Mo8-FET (switching element), D and -D
ll to I)mn are photoelectric conversion units. ,

Claims (1)

[Claims] A plurality of first switching elements that are selectively opened are arranged to form a predetermined array, and further, corresponding to each of the plurality of first switching elements, a first switching element and a second switching element are arranged in a predetermined array. A photoelectric conversion section electrically connected to the photoelectric conversion section and a second switching element electrically connected to the photoelectric conversion section are arranged, and when the second switching element of Uenishi 1 is in the open state, the above-mentioned When the charge obtained by the photoelectric conversion section is removed via the second switching element and does not become a signal charge, and the second switching element is closed, the charge obtained by the photoelectric conversion section becomes a signal charge. A solid-state imaging device in which a signal is derived from the signal charge through the first switching element to obtain an imaging output signal.