JPS61207935A - solid state imaging device - Google Patents

Abstract

PURPOSE:To make a titled device small in size without requiring a space for scanning a reference temperature plate, or a space of a chopper mechanism, by interposing a black body surface between mirror surfaces of a rotary polygon mirror. CONSTITUTION:A rotary polygon mirror 3 is provided with eight surfaces of plane reflecting mirror surfaces 3m, and two surfaces of black body surfaces 3b provided on symmetrical positions, and rotates in the direction as indicated with an arrow vertical to a photodetecting element array 1. A temperature radiation of the black body surface 3b is detected in a reference temperature signal period T2 in which the black body surface 3b is in a position for expecting the photodetecting element 1, namely, the pupil of a condensing lens 2, a clamp pulse is synchronized with it and impressed to a clamper and its potential is clamped to a prescribed reference temperature voltage VS, and an output of the clamper becomes a signal provided with a reference temperature signal period. A scanning angle of the rotary polygon mirror is equal to a visual field angle, and a space for scanning a reference temperature plate, and a space of a chopper mechanism are unnecessary, therefore, it is realized to make a device small in size remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a solid-state imaging device, particularly to a solid-state imaging device equipped with a scanning system using a rotating polygon mirror, and relates to an improvement in a method for setting a reference potential of an output signal thereof.

For example, there is an increasing trend to utilize thermography technology for exploration of weather, ocean currents, geology, etc., medical diagnosis, industrial inspection, management, etc.

Scanning systems using rotating polygonal mirrors are often used in thermography apparatuses, but since conventional scanning systems make the apparatus large and inconvenient, there is a strong demand for improvement.

[Conventional technology]

Thermography requires a solid-state imaging device to obtain highly sensitive infrared two-dimensional images in real time, but two-dimensional images are obtained by combining photodetectors arranged in a one-dimensional array and a rotating polygon mirror. Many scanning methods are currently in use.

In other words, the photodetecting element includes a photovoltaic type that has a pn junction and generates an electromotive force depending on the incident light, a photoconductive type that has an electric resistance that changes depending on the incident light, and a photoconductive type that has a pn junction and generates an electromotive force depending on the incident light, and a photoconductive type that has a potential well formed in a semiconductor substrate. MI where carriers are accumulated according to the incident light
There are S-shaped and other types, and these photodetecting elements form a one-dimensional array.

Conventionally, by using this photodetecting element array and a rotating polygon mirror that rotates in a direction perpendicular to the photodetecting element array,
A two-dimensional image is obtained by the operation as schematically shown in ).

In the figure, reference numeral 1 denotes a photodetecting element arranged in a one-dimensional array in a direction perpendicular to the plane of the paper, 2 a condenser lens, 23 a rotating polygon mirror, 24 a light receiving window, and 25 a reference temperature plate. Rotating polygon g of this conventional example! Reference numeral 23 is equipped with an eight-sided plane reflecting mirror, and rotates in the direction of the arrow parallel to the plane of the paper.

The angle of incidence of the light reflected by one surface of the rotating polygon mirror 23 and focused on the photodetecting element l by the condensing lens 2 onto the light receiving window 24 is rotated as shown in FIGS. polygon mirror 2
3, scanning is performed in a direction perpendicular to the photodetecting element array 1 at a viewing angle determined by the light receiving window 24, and then the reference temperature plate 25 is observed as shown in the same figure (C1). A scan is performed.

In this way, in order to repeat the scanning of the object and the observation of the reference temperature plate 25 one after another on each mirror surface, the rotating polygon mirror 23 is made large and its scanning angle is expanded beyond the necessary viewing angle.

For example, when the photodetection element 1 is of the photoconductive type, the photodetection amplification circuit is configured as shown in FIG. 4, and the signal waveforms of each part of this circuit are changed as shown in FIG. Become. However, in Fig. 4, 11 is a constant current source, 12 is a preamplifier, 13 is a clamper, and 14 is a main amplifier, and Fig. 5(a) is the output of the preamplifier 12, and T is a visual field white signal. A period, T, indicates a signal during the reference temperature signal period, FIG.

In this photodetection amplification circuit, the resistance value of the photodetection element 1 changes according to the number of incident photons, and this is input as a voltage change from the preamplifier 12, which obtains the output shown in FIG. Clamp pulses φ and L are applied to the clamper 13 in synchronization with the scanning of the temperature plate 25, and its output is clamped to the voltage Vs corresponding to the reference temperature, as shown in FIG.
) level.

Furthermore, as a reference temperature level setting method different from the conventional example, a chopper method is also used in which a reference temperature plate is inserted into and removed from the optical path, but in this method, the configuration and dimensions of the device are restricted by the chopper mechanism. There is.

[Problem that the invention seeks to solve]

As explained above, a solid-state imaging device used for thermography requires means for setting a reference temperature level, but the volume of conventional devices is increased for this purpose.

In order to meet the demands of solid-state imaging devices from various fields of use, such as smaller size, lighter weight, and improved operability, improvement of this reference temperature level setting means has become an important issue.

[Means for solving problems]

The above-mentioned problem is that a light detecting element and a rotating polygon mirror are provided, a black body surface is interposed between the mirror surfaces of the rotating polygon mirror, and an output signal is detected when the black body surface is at a position looking into the light detecting element. This problem is solved by the solid-state imaging device according to the present invention, which clamps the potential to a potential corresponding to the temperature of the black body surface and uses this potential as the reference potential of the output signal.

[For production]

According to the present invention, a rotating polygon mirror is provided with at least one black body surface inserted between the mirror surfaces, and this black body surface is maintained at a reference temperature, so that when the black body surface is at a position looking into a photodetector element, The output signal is clamped to a predetermined potential and used as a reference potential for the output signal.

This method of setting the reference potential of the output signal makes it possible to match the scanning angle of the rotating polygon mirror to the required viewing angle and reduce the size of each mirror surface and optical path, and also eliminates the need for a chopper mechanism, making it possible to Smaller size, lighter weight, improved operability, etc. are achieved.

〔Example〕

The present invention will be specifically explained below using examples.

FIG. 1 is a schematic perspective view showing scanning by a rotating polygon mirror of an embodiment of the solid-state imaging device according to the present invention.

In the figure, 1 is a photodetecting element arranged in a one-dimensional array, 2 is a condenser lens, 3 is a rotating polygon mirror, 3I11 is its mirror surface, and 3b is a black body surface according to the present invention. The rotating polygon mirror 3 of this embodiment includes eight flat reflecting mirror surfaces 3m and two blackbody surfaces 3b provided at symmetrical positions, and includes a photodetecting element array 1.
Rotate in the direction of the arrow perpendicular to .

This blackbody surface 3b is a surface whose radiation coefficient is considered to be 1,
Maintained at reference temperature.

The photodetection and amplification circuit of this embodiment is constructed in the same manner as the conventional example described above with reference to FIG.

It will look like Figure 2. However, in the same figure (al is the output of the preamplifier 12, T1 is the visual field white signal period, T2 is the signal between the reference temperature signals, (b) is the clamp pulse φ, and (C) is the clamp pulse). This is the output of 13.

In this embodiment, the reference temperature signal period T is such that the black body surface 3b is in a position where it looks into the pupil of the photodetecting element 1, that is, the condenser lens 2.
2, the temperature radiation of the black body surface 3b is detected as shown in FIG. 2(a), and the clamp pulse φCL is synchronized with the clamper 1.
3 and a predetermined reference temperature voltage ■.

The output of the clamper 13 is clamped to the second
The signal is assumed to have a reference temperature signal period as shown in Figure (C).

In this example, the scanning angle of the rotating polygon mirror is made equal to the viewing angle,
Since the space for scanning the reference temperature plate and the space for the chopper mechanism are unnecessary, a significant reduction in size is achieved compared to the conventional example.

In the embodiment, the number of photodetecting elements 1 is, for example, 100 to 200.
It is assumed that one horizontal scan of the rotating polygon mirror 3 forms one frame, or one screen. However, if the number of elements in the photodetecting element array is, for example, about 50 or less, rotation with a tilt angle given to the mirror surface is possible. The present invention can be similarly applied to a solid-state imaging device in which vertical scanning is performed using a polygon mirror and one screen is formed by multiple scans.

Furthermore, the above explanation is for the case of object plane scanning in which the rotating polygon mirror is placed on the object side of the condensing lens, but for image plane scanning in which the rotating polygon mirror is placed between the condensing lens and the photodetector element. The present invention can be similarly applied to these cases.

〔Effect of the invention〕

As explained above, according to the present invention, the scanning angle of the rotating polygon mirror of the solid-state imaging device is made larger than the viewing angle, and the space for scanning the reference temperature plate or the space for the chopper mechanism becomes unnecessary. The structure has been streamlined and significantly downsized, and operability has also been improved.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing scanning by a rotating polygon mirror in an embodiment of the solid-state imaging device according to the present invention, FIG. FIG. 4 is a schematic diagram showing a conventional example of two-dimensional scanning, FIG. 4 is a circuit diagram showing an example of a photodetection amplification circuit, and FIG. 5 is a diagram showing signal waveforms at various parts of the conventional photodetection amplification circuit. In the figure, 1 is a one-dimensional array of photodetecting elements, 2 is a condenser lens, 3 is a rotating polygon mirror, 3m is its mirror surface, and 3b
11 is a constant current source, 12 is a preamplifier, 13 is a damper, and 14 is a main amplifier. % 1 Figure 2 Figure 1f, 3 Figure v5 Kaya 4 Figure A S Figure

Claims (1)

[Claims] A light detecting element and a rotating polygon mirror are provided, a black body surface is interposed between the mirror surfaces of the rotating polygon mirror, and an output signal when the black body surface is in a position facing the light detecting element is determined as the temperature of the black body surface. A solid-state imaging device characterized by clamping to a corresponding potential and using the potential as a reference potential of an output signal.