Radiant energy – Invisible radiant energy responsive electric signalling – Infrared responsive
Patent
1993-05-21
1995-05-30
Hannaher, Constantine
Radiant energy
Invisible radiant energy responsive electric signalling
Infrared responsive
G01J 502, H01L 310224
Patent
active
054204267
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a pyroelectric device used as an infrared-ray sensor and heat sensitive device.
A pyroelectric device can be used as an infrared-ray sensor using a pyroelectric element composed of a material such as, for example, PVDF (polyvinylidene fluoride), PZT (lead zirconate titanate) or the like, or can be used as a sensing device such as a flame sensor disposed in a tunnel or the like to detect infrared rays of flame when fire is caused, or can be used as an intrusion detector used in a security system for detecting infrared rays from a human body.
Conventionally, as shown in FIG. 6, a pyroelectric device is arranged such that a pyroelectric member 40 and a printed board 41 are disposed on a base comprising stem 42 composed of metal or the like, and are sealed by a frame member comprising a can 43 composed of a steel plate or the like covering the upper periphery of the stem 42. The printed board 41 includes circuit elements 61 such as a field effect transistor (FET) or the like mounted thereon to output the intensity of infrared rays detected by the pyroelectric member 40 in the form of an electric signal. More specifically, the can 43 is provided with a light transmitting window hole 44 through the ceiling thereof so that unillustrated infrared rays emitted from the flame of, for example, a fire or the like are irradiated to the pyroelectric member 40 through the window hole 44. A filter 45 composed of, for example, silicon which is excellent in infrared ray transmittance is disposed over the window hole 44 to seal the same and enable the infrared rays to be transmitted therethrough. The sealing by and the bonding of the filter 45 is performed by forming an adhesive-bonding portion 46 with an adhesive such as an epoxy resin or the like.
Although the casing of the pyroelectric device is composed of the can 43 and stem 42 as described above, the sealed type pyroelectric device is formed in such a manner that the can 43 and stem 42 are fused or adhesive-bonded to each other at the sealing portion 47 along the periphery of the stem. As shown in FIG. 6, three lead terminals, that is, a ground terminal. 48, a source terminal 49 and a drain terminal 50 extend from the stem 42 and the aforesaid electric signal is output to an unillustrated main electric circuit through these lead terminals. In this case, although the ground terminal 48 is directly connected to the stem 42, the two other terminals, that is, the source terminal 49 and drain terminal 50 are fixed to the stem 42 in a sealed state through insulating members 51 so as to be insulated from the stem 42.
Arrangement of the pyroelectric member 40 will be described in detail with reference to the enlarged cross sectional view shown in FIG. 7. The pyroelectric member 40 is disposed on the printed board 41 through a base member 58, and keyhole-shaped electrodes 52 and 53 each composed of a protecting rectangular portion and a disc-shaped portion are formed respectively on the upper and lower surfaces of the pyroelectric member 40 by vapor deposition or the like. The disc-shaped portions 54 and 55 of these electrodes are disposed to confront to each other across the pyroelectric member 40, and the projecting portions 56 and 57 thereof are disposed so as to extend from the disc-shaped portions 54 and 55 to the right and left sides of the pyroelectric member 40, respectively. The electrodes 52 and 53 are composed of an infrared ray absorbing material such as nickel chromium alloy, gold black or the like.
The pyroelectric member 40, base member 58 and printed board 41 are bonded and fixed to each other through a suitable material, respectively, and electrically conductive adhesives 59 and 60 are applied between the electrodes 52 and 53 on the upper and lower surfaces of the pyroelectric member 40 and unillustrated circuit patterns of the printed board 41 so that electric conductivity is established therebetween. An electrically conductive adhesive mixed with silver filler or the like is used as the electricall
REFERENCES:
Patent Abstracts of Japan, vol. 5, No. 30 (E-47) Feb. 24, 1981.
Patent Abstracts of Japan, vol. 8, No. 101 (P-273)(1538) May 12, 1984.
Patent Abstracts of Japan, vol. 7, No. 196(P-219)(1341) Aug. 26, 1983.
Hannaher Constantine
Nohmi Boasai Ltd.
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