JPH11132860A - Solid imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously obtain image signals of a visible light and an invisible light by setting a differential amplifier for detection of only a temperature change component at an invisible light-detecting part. SOLUTION: Invisible light detection part 430 and visible light detection part 440 constitute a unit pixel 403. The unit pixel 403 are arranged in two dimensions. When the pixel 403 is selected, a signal charge of a visible light stored in a photodiode 414 is read out to a vertical visible signal line 422 through a first vertical MOS switch 424, read out to a horizontal visible signal line 423 through a first horizontal MOS switch 425 and then taken out as a visible image signal from a first output amplifier 420. Similarly, a current flows from a bias power source 408 through a second vertical MOS switch 404, a bolometer 402, a vertical invisible signal line 412, a second horizontal MOS switch 405 and a horizontal invisible signal line 413 to a load resistor 409, and is taken out as an invisible image signal from a second output amplifier 410.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image sensor for simultaneously imaging a plurality of wavelength bands such as visible light and invisible light.

[0002]

2. Description of the Related Art Among infrared rays, in the field of infrared imaging (hereinafter, IR is abbreviated as IR), since an electronic scanning IR camera was put into practical use in 1988, the application has been expanded mainly in the field of surveillance cameras. Have been doing. In particular, the incident I
An IR-type in which the energy of R is converted into heat on a detector, the temperature change of the detector is measured, and an IR image is captured.
In contrast to FPA (image sensors used in the field of visible light, Focal is generally used in the field of invisible light such as infrared light.
A Plane Array (abbreviated as FPA, which will be used below when limited to invisible light imaging only) has a feature that cooling is unnecessary, and is suitable for miniaturization.

[0003] Uncooled IR detectors include polycrystalline Si (P
Bolometer method and BST that use the property that the resistance value of materials such as oly-Si) and Ti change with temperature
(Baruim-Strontium-Titanate) and PZT (Lead Scan)
There is a ferroelectric method in which a pyroelectric material such as dium titanate) simultaneously uses a pyroelectric effect caused by temperature and a change in dielectric constant.
12 μm. In the following, the bolometer method is B method,
The ferroelectric method is abbreviated as F method.

FIG. 1 shows the configuration of a B-type uncooled FPA. A unit pixel 103 is constituted by the diode 101 and the bolometer 102, and the unit pixels are two-dimensionally arranged.

The two-dimensional scanning of the bolometer pixel 103 is as follows:
This is performed by sequentially selecting pixels by the vertical MOS switch 104 to which the output pulse of the vertical shift register 106 is applied and the horizontal MOS switch 105 to which the output pulse of the horizontal shift register 107 is applied.

When the pixel 103 is selected, a current flows from the bias power supply 108 to the load resistor 109 via the horizontal input line 111, the pixel 103, the vertical signal line 112 and the horizontal output line 113. Bolometer 102
An image signal can be obtained by measuring the voltage drop across the terminals by the amplifier 110.

FIG. 2 shows the configuration of an F-type uncooled FPA. A unit pixel 203 is constituted by a pyroelectric material detector 201 having one end connected to a bias power supply 208 and a signal conversion circuit 202 using an operational amplifier 209, and the unit pixels are arranged two-dimensionally. The two-dimensional scanning of the pixel 203 is performed by the reed switch 204 to which the output pulse of the vertical multiplexer 206 is applied and the horizontal multiplexer 207.
This is performed by sequentially selecting pixels.

When the pixel 203 is selected, the electric charge generated by the pyroelectric material detector 201 (the electric charge flowing in accordance with the spontaneous polarization and the change in the capacitance of the detector) is converted by the signal conversion circuit 202 in the unit pixel 203. The voltage is converted to a voltage, and is output to an external amplifier 210 via a reed switch 204 and an amplifier 205 provided at the end of the vertical signal line 212.

[0009]

SUMMARY OF THE INVENTION IR cameras for monitoring crime prevention and in-vehicle IR cameras, which have been increasing in demand recently from the standpoint of safe driving support, are required to be able to detect the body temperature of humans and animals. It is desirable to display a human body or an animal detected by an IR camera on a scene observed by a visible light camera.

However, in order to meet this need with conventional techniques, it is necessary to prepare two cameras, one for visible light and the other for invisible light, and the two cameras have different optical axes. However, it was impossible to completely match the two images even when they were superimposed.

In that case, it is sufficient that one imaging device has both visible light and invisible light detectors from the beginning.
Until now, it has been impossible in principle to realize a single lens optical system that transmits visible light and invisible light at the same time, and the idea of an image sensor that simultaneously captures visible light and invisible light has not emerged.

Further, there is a method in which a B-type IR detector supplies a current to detect a change in resistance, and an F-type IR detector supplies a current to detect spontaneous polarization and a change in capacitance. Because of its use, there has been no successful example of mounting a current detection type uncooled IR detector on a CCD image sensor that is currently most widespread and has the characteristic of low noise by detecting only signal charges.

[0013]

The present invention comprises a free-form surface reflection optical system and a solid-state image sensor, wherein the solid-state image sensor has pixels arranged in m rows and n columns (m and n are natural numbers) and scanning means. Wherein each of the pixels has a visible light detecting section and an invisible light detecting section, the invisible light detecting section is made of a bolometer or ferroelectric material, and the scanning means is a scanning circuit. And a signal transfer device or a charge transfer device, wherein the invisible light detection unit has a differential amplifier for detecting only a temperature change. It is.

Since each pixel of the image pickup device of the present invention has a visible light detecting section and an invisible light detecting section, the degree of coincidence between the visible light image and the invisible light image is high. The present invention is extremely useful not only for a camera for image recognition but also for image recognition for specifying or cutting out a person.

Further, the differential amplifier introduced into the invisible light detecting section of each pixel enhances the sensitivity of the invisible light, so that the current invisible light (that is, infrared light) which is at least one digit larger than that of the visible light detecting section. It is possible to reduce the area of the light (light) detection unit.

The free-form surface reflection optical system, which is a component of the present invention, can realize the same angle of view as the conventional lens optical system, and is an optical system for all the spectrum from ultraviolet to infrared. Practical performance can be realized with the optical resin molded reflecting mirror, so that the manufacturing time and cost can be significantly reduced.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 shows a free-form surface reflection optical system which is a main component of the present invention. As a result of reflection of incident light rays from a wide angle of view 301, 302 and 303 on reflection surfaces 303 and 304, R1 Is 305,
It is reproduced at the position. The reflecting mirrors 303 and 304 are designed to be so.

FIG. 4 shows a configuration in which the scanning means of the image pickup device, which is a main component of the present invention, is constituted by a scanning circuit of the MOS type and a signal line, and the invisible light detecting unit is of the B type.

The diode 401, the bolometer 402, and the second vertical MOS switch 404 constitute a B type infrared light detection pixel 430. The photodiode 414 and the first MOS switch 424 form a visible light detection pixel 440.
And the detection pixels 430 and 440 constitute a unit pixel 403 of the image sensor of the present invention.
Are arranged two-dimensionally.

The two-dimensional scanning of the unit pixel 403 is performed by the first vertical MOS switch 424 and the second vertical MOS switch 404 connected to the vertical transmission line 411 to which the output pulse of the vertical shift register 406 is applied, and the horizontal shift register. The first horizontal MOS to which the output pulse of 407 is applied
Switch 425 and second horizontal MOS switch 405
Is performed by sequentially selecting pixels.

When the pixel 403 is selected, the visible light signal charges stored in the photodiode 414 are transferred to the vertical visible signal line 422 via the first vertical MOS switch 424.
, And read out to the horizontal visible signal line 423 via the first horizontal MOS switch 425, and then taken out from the first output amplifier 420 as a visible image signal. Similarly, the second vertical MOS is supplied from the bias power supply 408 to the second vertical MOS.
A current flows to the load resistor 409 through the switch 404, the bolometer 402, the vertical invisible signal line 412, the second horizontal MOS switch 405, and the horizontal invisible signal line 413, and is extracted from the second output amplifier 410 as an invisible image signal.

FIG. 5 is a diagram in which the scanning means of the image sensor, which is a main component of the present invention, is constituted by a MOS scanning circuit and a signal line, and a differential amplifier is introduced into a B-system invisible light detecting section. It is.

The diode 501, the bolometer 502, and the second vertical MOS switch 504 constitute a B-type infrared light detection pixel 530, and the photodiode 514 and the first MOS switch 524 detect visible light detection pixels 540.
And the detection pixels 530 and 540 constitute a unit pixel 503 of the image sensor of the present invention.
Are arranged two-dimensionally.

The two-dimensional scanning of the unit pixel 503 is performed by the first vertical MOS switch 524 and the second vertical MOS switch 504 connected to the vertical transmission line 511 to which the output pulse of the vertical shift register 506 is applied, and the horizontal shift register. The first horizontal MOS to which the output pulse of 507 is applied
Switch 525 and second horizontal MOS switch 505
Is performed by sequentially selecting pixels.

When the pixel 503 is selected, the visible light signal charge stored in the photodiode 514 is transferred to the vertical visible signal line 522 via the first vertical MOS switch 524.
After being read out to the horizontal visible signal line 523 via the first horizontal MOS switch 525, it is extracted from the first output amplifier 520 as a visible image signal.

Similarly, when the pixel 503 is selected, the voltage generated by the current flowing from the bias power supply 508 to the second vertical MOS switch 504 and the bolometer 502 and the reference voltage generated by the dividing resistor 517 are stored in the pixel. And drives the invisible signal control MOS gate 516 with the output voltage obtained from the differential amplifier 515 to inject the invisible signal charge from the bias power supply 516 to the vertical invisible signal line 512. The electric charge injected into the vertical invisible signal line 512 flows to the load resistor 509 through the second horizontal MOS switch 505 and the horizontal invisible signal line 513, and
From the output amplifier 510 as an invisible image signal.

FIG. 6 shows an embodiment in which a CCD is used as a scanning means of an image sensor, which is a main component of the present invention, and a differential amplifier is introduced in a B type invisible light detecting section.

The diode 601, the bolometer 602, and the second vertical MOS switch 604 form a B-type infrared light detection pixel 630, and the photodiode 614 and the first MOS switch 624 form a visible light detection pixel 640.
And the detection pixels 630 and 640 constitute a unit pixel 603 of the image sensor of the present invention.
Are arranged two-dimensionally.

The two-dimensional scanning of the unit pixel 603 is performed in the vertical CC
D654 and the horizontal CCD 655.

The vertical read pulse 651 (ΦVR) is applied to all the first vertical MOS switches 624 and the second vertical MOS switches 624.
When applied to the switch 604, both visible light signal charges and invisible light signal charges are simultaneously read out to the vertical CCD 654.

The signal charge of the visible light is
From 14, the first vertical is also read out to the vertical CCD 654 via the S switch 624.

The signal charge of the invisible light is supplied to the bias power supply 60
8 to the second vertical MOS switch 604, the bolometer 6
02 and the reference voltage generated by the dividing resistor 617 are input to the differential amplifier 615 in the pixel, and the output voltage obtained from the differential amplifier 615 is used to control the invisible signal control MOS gate 616. To inject an invisible signal charge from the bias power supply 516 into the vertical CCD 654.

The visible light signal charges and the invisible light signal charges read into the vertical CCD are read into the horizontal CCD via the horizontal MOS switch 653, and the visible light signal charges and the invisible light signal charges are output at the output unit. The signals are sorted and extracted as image signals from the amplifier 620 for visible light and the amplifier 610 for invisible light.

Since the vertical CCD and the horizontal CCD shown in FIG. 6 simultaneously transfer the visible light signal charges and the invisible light signal charges, the density is doubled as compared with the vertical CCD and the horizontal CCD used in the conventional CCD image sensor. There is a need.

FIG. 7 shows an example of a specific structure of the unit pixel 603 in FIG. p epi region 702 on n substrate 701
The n region 703 formed on the surface corresponds to the visible light photodiode 614, and the charge transfer unit 707 is
Corresponding to 54. The infrared light photoelectric conversion unit 704 is the bolometer 602, the infrared light readout electrode 706 corresponds to the invisible signal control MOS gate 616, and the n + region 70.
5, a bias power supply 616 is applied.

FIG. 8 shows an example in which a pyroelectric material is used for the infrared light photoelectric conversion unit 804 in place of the bolometer of FIG. 7, and one of the gates of the invisible signal control MOS gate 616 together with the infrared light readout electrode 706. It has a structure that constitutes a part.

[0038]

As is apparent from the above description,
According to the present invention, it is possible to realize an imaging device capable of simultaneously obtaining image signals of visible light and invisible light, and to provide an element configuration that is not affected by materials and the like that can be used as a scanning unit and a detection unit of invisible light. Therefore, the practical effect provided by the present invention is extremely large.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit configuration of a conventional bolometer type FPA.

FIG. 2 is a diagram showing a circuit configuration of a conventional ferroelectric FPA;

FIG. 3 is a diagram showing a free-form surface reflection optical system which is a component of the imaging apparatus of the present invention.

FIG. 4 is a diagram showing a first embodiment of the present invention provided with a visible light photodiode and a bolometer type invisible light detector using a MOS type scanning means.

FIG. 5 is a diagram showing a second embodiment of the present invention using a MOS type scanning means and a differential amplifier in a bolometer type invisible light detection pixel section.

FIG. 6 is a diagram showing a third embodiment of the present invention using a CCD type scanning unit and provided with a visible light photodiode and a bolometer type invisible light detection unit.

FIG. 7 is an element structure diagram of a unit pixel according to a third embodiment of the present invention.

FIG. 8 is an element structure diagram of a unit pixel in a case where an invisible light detection unit according to a third embodiment of the present invention is made of a ferroelectric type pyroelectric material.

[Explanation of symbols]

 401 Diode 402 Bolometer 403 Pixel 404 Phototransistor 405 Horizontal Moss switch 406 Vertical scanning circuit 407 Horizontal scanning circuit

Claims (7)

[Claims] 1. A solid-state imaging device for converting an optically recognized image into an electric signal, and an optical system for guiding light to be received to the solid-state imaging device, wherein the solid-state imaging device has m rows and n columns ( A solid-state imaging device comprising: pixels arranged in a matrix (m and n are natural numbers) and a scanning unit, wherein each pixel has a visible light detecting unit and an invisible light detecting unit. 2. A solid-state imaging device for converting an optically recognized image into an electric signal, and an optical system for guiding light to be received to the solid-state imaging device, wherein the solid-state imaging device has m rows and n columns ( m and n are natural numbers), each pixel has a scanning unit, and each pixel has a visible light detecting unit and an invisible light detecting unit, and the invisible light detecting unit is made of a bolometer type material. A solid-state imaging device characterized in that: 3. A solid-state imaging device for converting an optically recognized image into an electric signal, and an optical system for guiding light to be received to the solid-state imaging device, wherein the solid-state imaging device has m rows and n columns ( m and n are natural numbers), each pixel has a scanning unit, and each pixel has a visible light detection unit and an invisible light detection unit, and the invisible light detection unit is made of a ferroelectric material. A solid-state imaging device, comprising: 4. A solid-state imaging device for converting an optically recognized image into an electric signal, and an optical system for guiding light to be received to the solid-state imaging device, wherein the solid-state imaging device has m rows and n columns ( m and n are natural numbers), and each pixel has a visible light detecting unit and an invisible light detecting unit, and the scanning unit includes a scanning circuit and a signal line. A solid-state imaging device. 5. A solid-state imaging device for converting an optically recognized image into an electric signal, and an optical system for guiding light to be received to the solid-state imaging device, wherein the solid-state imaging device has m rows and n columns ( m and n are natural numbers) and each pixel has a visible light detection unit and an invisible light detection unit, and the scanning unit is a charge transfer device. Solid-state imaging device. 6. A solid-state imaging device for converting an optically recognized image into an electric signal, and an optical system for guiding light to be received to the solid-state imaging device, wherein the solid-state imaging device has m rows and n columns ( pixels having both m and n are natural numbers) and scanning means, each of the pixels has a visible light detecting section and an invisible light detecting section, and the invisible light detecting section detects only a temperature change. A solid-state imaging device having a differential amplifier for performing the operation. 7. The solid-state imaging device according to claim 1, wherein the optical system uses free-form surface reflection.