Radiant energy – Invisible radiant energy responsive electric signalling – Infrared responsive
Patent
1984-04-09
1986-07-22
Church, Craig E.
Radiant energy
Invisible radiant energy responsive electric signalling
Infrared responsive
250349, 250350, 250351, 331 66, G01J 562
Patent
active
046021590
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an infrared detector.
BACKGROUND OF THE INVENTION
Conventionally, as an infrared detector, either a thermal type or photo type has been used. Of these types, for measurement of temperatures in living space, the thermal type detector is used which is of relatively high sensitivity in a wavelength range of 5 .mu.m or more and is inexpensive. Typically available as the thermal type detector is a pyroelectric type element which is used for an electronic oven, crime prevention and the like. In addition, a thermistor bolometer, a thermopile and the like are available. All of these devices or elements, however, provide analog outputs and have unsatisfactory noise-proof properties. Therefore, the advent of an infrared detector having digital outputs has been desired.
With the development of microcomputers, on the other hand, the advent of an element has been desired which is capable of directly inputting digital signals to a microcomputer.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a thermal type infrared detector which has digital output signals for satisfying these requirements and which is of high sensitivity and low cost.
The infrared detector of the present invention makes use of the fact that when infrared rays are irradiated on an elastic surface wave propagation path of an elastic surface wave propagation member in an elastic surface wave oscillator, the oscillation frequency changes in accordance with the intensity of the infrared rays.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of an infrared detecting unit used in an infrared detector according to the present invention,
FIG. 2 is a diagram showing the change in oscillation frequency upon opening or closing of a shutter in the infrared detecting unit shown in FIG. 1,
FIG. 3 is a diagram for explaining timings for the opening or closing of the shutter and counting of clock pulses in the infrared detecting unit shown in FIG. 1,
FIG. 4 is a block diagram for processing signals from the infrared detecting unit shown in FIG. 1,
FIG. 5 is a diagram showing the relation between the temperature of an object to be detected and clock pulse count, obtained from the high-sensitivity infrared detector of the present invention.
FIG. 6 is a diagram for explaining the principle of the infrared detector according to the present invention,
FIGS. 7 and 8 are block diagrams showing constructions of specified examples of the infrared detector according to the present invention,
FIG. 9 is a diagram showing an example of the relation between the temperature of the object being detected and the output,
FIG. 10 is a block diagram showing another specified example of the infrared detector according to the present invention,
FIG. 11 is a diagram for explaining the operation of the example shown in FIG. 10,
FIG. 12 is a diagram showing still another specified example of the present invention, and
FIG. 13 is a diagram showing an example of an actual measurement according to the example shown in FIG. 12.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The principle of an infrared detector of the present invention will first be described. FIG. 1 shows a construction of an infrared detecting unit used in the infrared detector of the present invention. In the figure, numeral 1 denotes a piezoelectric substrate made of, for example, lithium niobate, and numerals 2 and 3 denote interdigital electrodes for elastic wave transmission and for elastic wave reception, respectively, which are formed on a polished surface of the piezoelectric substrate 1 through vapor deposition, for example. One terminal of each of the elastic wave transmission interdigital electrode 2 and elastic wave reception interdigital electrode 3 is grounded and the other terminal thereof is connected to an output side and an input side of amplifier 4, respectively. Numeral 5 denotes an output terminal connected to the output side of the amplifier 4 via a capacitor 6.
As described above, a feedback type oscillator 7
REFERENCES:
patent: 3457412 (1969-07-01), Cary
patent: 3879992 (1975-04-01), Bartera
patent: 4023088 (1977-05-01), Fowler
patent: 4197530 (1980-04-01), Laue
patent: 4209725 (1980-06-01), Dieulesaint et al.
Inaba Ritsuo
Kasahara Yukio
Church Craig E.
Hannaher Constantine
Matsushita Electric - Industrial Co., Ltd.
LandOfFree
Infrared detector does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Infrared detector, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Infrared detector will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-867316