Radiant energy – Invisible radiant energy responsive electric signalling – Infrared responsive
Reexamination Certificate
1998-10-07
2001-05-22
Hannaher, Constantine (Department: 2878)
Radiant energy
Invisible radiant energy responsive electric signalling
Infrared responsive
C250S338300, C250S332000, C250S330000, C250S340000, C250S342000
Reexamination Certificate
active
06236046
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an infrared sensor for detecting infrared in response to thermal variation due to absorption of infrared.
DESCRIPTION OF RELATED ART
Infrared detecting elements for use in the infrared sensors have been generally classified into quantum type and thermal type in accordance with operational principle. While the quantum type infrared detecting element is extremely high in the sensitivity, there have been such problems due to the necessity of using it at lower temperatures with the element itself cooled that the sensor is difficult to handle, manufacturing costs become high, dimensions in a system including means for cooling the element become larger, and so on.
In contrast, the thermal type infrared detecting element is less sensitive than the quantum type but is not required to be cooled and simpler in the structure, and has been utilized widely in various practical ways of use, because of such advantages as low manufacturing costs, minimized dimensions and so on.
The infrared sensors of this type have been disclosed in Japanese Utility Model Laid-Open Publication No. 61-50232 by K. Kitamura et al., and U.S. Pat. No. 4,258,260 by H. Obara et al.
In a typical arrangement of another known thermal type sensor, a first infrared detecting element for infrared detection and a second infrared detecting element for temperature compensation are concurrently disposed in a container comprising a cap and a stem, and an infrared shielding plate for preventing the incidence of infrared onto the second infrared detecting element from occurring is provided at part of front face of an infrared transmitting filter closing an incident window provided in the cap, or the infrared transmitting filter is provided only at a position opposing the first infrared detecting element so that the infrared will not be incident on the second infrared detecting element.
In the above sensor arrangement, however, there is present a space between the second infrared detecting element for the temperature compensation and the infrared shielding plate or the like so that, in order to completely shield the infrared apt to be incident on the second infrared detecting element, it will be necessary that an angle of view of the first infrared detecting element is set, an aperture is provided for allowing the infrared only within the range of the set angle of view to be incident, and an infrared shielding section is provided to be sufficiently larger than the second infrared detecting element for completely shielding the infrared present outside the range of set angle of view. In this case, the incidence of infrared to the first infrared detecting element from a certain direction is caused to be hindered, so that there will arise a problem that the sensitivity may happen to be remarkably varied depending on the direction of incidence of the infrared.
SUMMARY OF THE INVENTION
An object of the present invention is to overcome the foregoing problems and to provide an infrared sensor capable of restraining any deterioration in the detecting precision due to variation in the ambient temperature, only at lower costs required.
According to the present invention, the above object can be attained by means of an infrared sensor wherein first and second infrared detecting elements have respectively a temperature sensing section provided for converting a temperature variation of the section due to incident infrared into an electric detection signal, and the temperature sensing section is disposed in a container having an infrared incident window for enlarging the temperature variation, characterized in that the first infrared detecting element for infrared detection and the second infrared detecting element for temperature compensation are disposed in the container, the temperature sensing section of the first infrared detecting element is supported in non-contacting state with respect to a supporting part of a supporting substrate for the element, the first infrared detecting element is supported by the supporting substrate in opposition to the infrared incident window, and the second infrared detecting element is shielded by the supporting substrate of the first infrared detecting element from the infrared incident. With this arrangement of the infrared sensor, it is enabled to restrain any deterioration in the detecting precision of the infrared due to variation in the ambient temperature without causing any hindrance to the compensation for the ambient temperature nor any increase in the costs, while the second infrared detecting element for the temperature compensation is disposed in the same container as that of the first infrared detecting element.
Other objects and advantages of the present invention shall become clear as the description of the invention advances as detailed with reference to preferred embodiments shown in accompanying drawings.
REFERENCES:
patent: 4258260 (1981-03-01), Obara et al.
patent: 5583058 (1996-12-01), Utsumi et al.
patent: 61-50232 (1986-04-01), None
Aizawa Kouichi
Honda Yoshiaki
Ichihara Tsutomu
Watabe Yoshifumi
Hannaher Constantine
Israel Andrew
Lynn & Lynn
Matsushita Electric & Works Ltd.
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