JPS6093928A - Pyroelectric type camera apparatus - Google Patents

Abstract

PURPOSE:To remove effect of temperature with a reduction in step signals contained in heat image signals by extracting a temperature change component of a chopper arranged in front of a pyroelectric type pickup element from the output thereof to control the surface temperature thereof. CONSTITUTION:Output of a preamplifier 8 is applied to a variation detecting circuit 12 to detect the amplitude and phase of the temperature component of a chopper and the results are applied to one input terminal of an AND circuit 22. On the other hand, a square wave generated with the opening or closing of a chopper 3 from a chopper rotation synchronizing circuit 17 is inverted with an inverter 20 and applied to the other terminal of the AND circuit 22. Output of the AND circuit 22 is applied to a cooling/heating discrimination circuit 23'. After the cooling/heating discrimination circuit 23' determines which mode should be entered between cooling and heating, the output of the variation detecting circuit 21 regulates temperature controls 23 for blowers and like to control the surface temperature of the chopper 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a pyroelectric camera device using a pyroelectric image pickup tube.

Conventional configuration and its problems In a pyroelectric image pickup tube, infrared rays emitted from the surface of an object to be measured according to its temperature are focused on a target by an optical system consisting of a germanium lens, and an infrared intensity distribution image is calculated based on the temperature. Change to a distribution image of changes. The target made of pyroelectric material is polarized perpendicularly to the surface, and an infrared absorbing film that also serves as the second page of signal extraction electrodes is deposited on the entire surface of the infrared rays incident surface.The back surface of the target, that is, the electron beam scanning surface, has a temperature A charge distribution image is induced by the pyroelectric effect caused by the change. This is scanned with an electron beam to obtain a temperature distribution image signal.

The pyroelectric effect is a change in the surface charge of the target due to temperature change, so in order to obtain a surface temperature distribution image of an object in a stationary state with no temperature change using a pyroelectric vidicon, use a chopper etc. to It is necessary to periodically block the infrared rays and modulate them alternately between positive and negative, or to move a pyroelectric camera device.

In this case, the reproduced object image is the difference between the infrared radiometer of the object to be measured and the infrared radiometer of the surrounding or background image, which is reproduced as a thermal image.

The thermal image based on this difference is reproduced by alternating positive and negative changes due to the chopper operation, but in reality, it is a thermal image signal obtained by adding the temperature of the chopper itself that occurs during the period when the lens incident light is blocked (that is, during the period when the chopper is closed). will be played.

Therefore, it is not possible to obtain an accurate heat source for the object to be measured (3 bases), signal processing cannot be performed effectively, and in general, considering the case where there is a large difference between the temperature around the object image or the background and the chopper temperature, 'The amplifier itself after conversion has required a large dynamic range.

OBJECTS OF THE INVENTION The object of the present invention 1111 is to obtain a pyroelectric camera device which is completely unaffected by the temperature of the chopper with a simple circuit configuration.

Structure of the Invention Kipp@4i-1: Extract the chopper temperature change component generated by the chopper that opens and closes in front of the pyroelectric image pickup tube.
This is a pyroelectric camera device that gradually controls the surface temperature based on the signal amplitude and signal phase to remove the signal included in the thermal image signal.

Embodiments The embodiments of the present invention will be described in detail below with reference to the drawings.]
do.

FIG. 1 shows the overall configuration of a pyroelectric camera device according to an embodiment of the present invention. In the figure, infrared rays emitted from a subject 1 pass through an infrared imaging lens 2 through which a material such as germanium is removed, and an infrared light image 4 with a wavelength of 8 μm to 14 μm is formed using a pyroelectric material in a pyroelectric imaging tube 6. The image is focused on the target 5.

The infrared light image, that is, the thermal image signal 4, which is provided at the same time as the chopper 3it lens 2 and the target 6, generates a signal that changes between positive and negative signals in synchronization with the chopper 3 by cutting off the incident light one step at a time. rrt from the target terminal as follows.

8 of chopper 3 is the part that allows the incident light to pass through the lens, B1
1'j: Part to be cut off. This chopper 3 is about 4
(The low-speed rotation of (2) is kept sufficiently low compared to the scanning period of one thermal image frame of the vidicon beam, which will be described later.

7 is a beam scanning deflection circuit. The horizontal and vertical scanning speeds are 15.75 kll and 60 m, respectively, which is the same as the specifications of conventional video cameras.

Targera: ・Output reliability: Approximately 0.3vPP with preamplifier 8
It is amplified to the extent that one can believe in one's utility. The output signals of the target 6 page 6 and the preamplifier 8 are a thermal image signal that changes positive and negative alternately in synchronization with the chopper, and a component radiated from the surface of the target (Fig. 2 (a)) according to the chopper temperature is superimposed. can be obtained. The waveform in this case is shown in FIG. 2(b).

The output of the preamplifier 8 is connected to a blanking pulse mixing circuit 10.
The waveform is shaped by the clip circuit 11 and output from the output terminal 12.

13 is a synchronization pulse generator horizontal for beam scanning.

In addition to supplying 100 driving pulses to the deflection circuit 7, one of the vertical synchronizing pulses (60 pulses) is supplied to the chopper rotation synchronization circuit 17.
/16 period square wave pulse is applied to chopper drive motor 16
Rotate at approximately 3.7 degrees. 14 is a light emitting diode, 1
A phototransistor 5 detects the position of the chopper 3 and returns its output to the chopper rotation synchronization circuit 17 to keep the chopper 3 synchronized.

Since the temperature of the chopper 3 is increased in accordance with the rise in temperature inside the camera, the level difference in the waveform shown in FIG. 2 (b) K due to the chopper temperature is expanded.

In the book published on page 9, the influence of this chopper temperature is removed as follows.

The output of the nfJ device width amplifier 8 is applied to the fluctuation detection circuit 21 to detect the amplitude and phase of the chopper temperature component, which is then
It is applied to one input terminal of the ND circuit 22.

On the other hand, the square wave generated by the chopper synchronization circuit 17 due to the opening and closing of the chopper is inverted by the inverter 20 and applied to the other terminal of the AND circuit WJ 20. AN
The output of the D circuit 22 is applied to a cooling/heating discrimination circuit 23'. The output of the fluctuation detection circuit 21 is the cooling/heating discrimination circuit 2.
After determining whether the mode should be cooling or heating at step 3', the temperature controller 23 such as a blower is controlled to control the surface temperature of the chopper 30. As a result, the temperature change in the chopper 3 is compensated for, and a waveform as shown in FIG. 2(C) is obtained from the output terminal 12.

Effects of the Invention As described above, the present invention extracts the temperature change component of the chopper disposed in front of the pyroelectric image sensor from the output of the pyroelectric image sensor to control the surface temperature of the chopper. The pyroelectric camera device reduces the level difference signal included in the thermal image, and detects the chopper temperature without installing a separate chopper surface temperature detection element, and controls the chopper surface temperature to eliminate the influence of the chopper temperature. Can be removed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of a pyroelectric camera device according to the present invention, and FIG. 2 is a waveform diagram for explaining the operation of the block diagram in FIG. 1. 1...Subject, 2...Lens, 3...
...Chopper, 4...Infrared light image, 5...
...Target, 6...Pyroelectric image pickup tube, 7
...Beam scanning deflection circuit, 8...Preamplifier, 9...Clamp circuit, 1o...
... Blanking pulse mixing circuit, 11 ... Clip circuit, 13 ... Synchronous pulse generator, 14
......Light emitting diode, 15...Phototransistor, 16...Chopper drive motor, 1
7...Chopper rotation synchronization circuit, 2o...
...Inverter, 21... Fluctuation detection circuit, 22
. . . AND circuit, 23 . . . Temperature adjustment circuit JP-A-93928 (3) child, 23' . . . Cooling heating control discrimination circuit.

Claims (1)

[Claims] A pyroelectric camera device comprising a barrel pyroelectric vidicon and a chopper arranged in front of it, and controlling the surface temperature of the chopper according to the amplitude and phase of a chopper temperature signal generated by opening and closing the chopper.