Radiant energy – Invisible radiant energy responsive electric signalling – Infrared responsive
Reexamination Certificate
1999-06-01
2001-12-04
Hannaher, Constantine (Department: 2878)
Radiant energy
Invisible radiant energy responsive electric signalling
Infrared responsive
C250S338300, C250S332000
Reexamination Certificate
active
06326621
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an infrared radiation detector.
The infrared radiation detector is used in sensing a thermal object such as human body and measuring the temperature of the thermal object.
Detection of a thermal object by means of infrared radiation detector has a wide application for, for example, crime prevention, traffic and disaster monitoring. The use of infrared radiation detector also facilitates measurement of the temperature of a thermal object without touching the body.
The infrared radiation detectors can be roughly classified into two types: quantum detector using a photovoltaic effect and thermal detector using heat generated by infrared radiation.
Of the two detectors, the thermal detector has been attracting attention greatly because it does not depend on the infrared wavelength and because it does not require cooling despite its lower sensitivity than the quantum detector. The thermal detector is subclassified into various types according to the principle of operation; pyroelectric detector, bolometer type detector, thermocouple detector, ferroelectric bolometer type detector, etc.
Of the various thermal detectors, the pyroelectric detector has been widely applied in human detection because of high sensitivity thereof. This detector comprises, for example, an MgO substrate having microcavities formed on the surface thereof by micromachining techniques (see Journal of Applied Physics, 32, 1993, pp. 6297-6300, by Kotani et al.) and a lead lanthanum titanate (PLT) ferroelectric thin film formed on the surface of the MgO substrate (see Journal of Applied Physics, 63(12), 1988, pp. 5868-5872, by Takeyama et al.). The resistive bolometer and the ferroelectric bolometer have been used in measuring temperature because they allow determination of an absolute value of temperature by a resistance and a dielectric constant.
Recently, there is a proposal of an tympanic thermometer using the thermal detector. The tympanic thermometer can measure the temperature of a subject in a short time by simple insertion of the thermometer into the host's ear. The detection mechanism of the tympanic thermometer is as follows: A sensor mounted in the thermometer senses infrared ray by a pyroelectric effect. The sensor detects a difference between the temperature of a piezoelectric chopper and that inside the ear. The temperature of the piezoelectric chopper is detected by a contact thermistor mounted on the pyezoelectric chopper in the thermometer. The difference between the temperature of the piezoelectric chopper and that of the ear is calculated, and a sum of the chopper's temperature and the temperature difference is output as the temperature of the subject.
In a practical thermal sensing system, a combination of plural different infrared radiation detectors may be used in order to have a desired function. For example, two infrared radiation detector units, one for detecting the presence of a thermal object and one for measuring the temperature of the detected thermal object, may be formed in a single system. For the infrared radiation detector unit for detecting a thermal object, either the pyroelectric detector or the ferroelectric bolometer utilizing a field-enhanced pyroelectric effect may be used. For the other for measuring the temperature of a heat source (thermal object), the resistive bolometer or the ferroelectric bolometer may be used.
BRIEF SUMMARY OF THE INVENTION
The object of the present invention is to provide a compact and high performance infrared radiation detector.
The infrared radiation detector in accordance with the present invention comprises:
a substrate; and
at least two infrared radiation detector units selected from the group consisting of a pyroelectric infrared radiation detector unit, a resistive bolometer type infrared radiation detector unit, and a ferroelectric bolometer type infrared radiation detector unit, the at least two infrared radiation detector units being disposed on the same side of the substrate.
In a preferred mode of the present invention, cavities are formed immediately underneath the infrared radiation detector units disposed on the substrate. Formation of such cavity inhibits thermal conduction between the infrared radiation detector units and the substrate, which results in improved sensitivity of the infrared radiation detector units.
In another preferred mode of the present invention, one of the infrared radiation detector units is a resistive bolometer type infrared radiation detector unit and the other is a pyroelectric infrared radiation detector unit or a ferroelectric bolometer type infrared radiation detector unit. A resistor of the former infrared radiation detector unit and one electrode of the latter infrared radiation detector unit are made of the same conductive material.
Simultaneous formation of the resistor with the electrode is preferable. For example, a conductive thin film is formed on the substrate preliminarily, which thin film is processed into the resistor and the electrode later on. As an alternative, a conductive thin film doubling as the resistor and another conductive thin film doubling as the electrode are formed into a desired shape at a predetermined site, respectively.
While the novel features of the invention are set forth particularly in the appended claims, the invention, both as to organization and content, will be better understood and appreciated, along with other objects and features thereof, from the following detailed description taken in conjunction with the drawings.
REFERENCES:
patent: 4501967 (1985-02-01), Shaulov
patent: 5426304 (1995-06-01), Belcher et al.
patent: 5559332 (1996-09-01), Meissner et al.
patent: 5929441 (1999-07-01), Beratan et al.
Tokumi Kotani, et al. “Fabrication Of A New Pyroelectric Infrared Sensor Using MgO Surface Micromachining”Jpn. J. Appln. Phys.vol. 32 (1993) pp. 6297-6300 Part 1, No. 12B, Dec. 1993.
Fujii Satoru
Kamada Takeshi
Kanno Isaku
Takayama Ryoichi
Tomozawa Atsushi
Akin Gump Strauss Hauer & Feld L.L.P.
Hannaher Constantine
Israel Andrew
Matsushita Electric - Industrial Co., Ltd.
LandOfFree
Infrared radiation detector and method of manufacturing the... 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 radiation detector and method of manufacturing the..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Infrared radiation detector and method of manufacturing the... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2591237