Radiant energy – Photocells; circuits and apparatus – Photocell controlled circuit
Patent
1992-09-14
1994-06-07
Westin, Edward P.
Radiant energy
Photocells; circuits and apparatus
Photocell controlled circuit
313538, H01J 4014
Patent
active
053191935
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a light-activated transducer and to a method of making it.
A known radiation-activated transducer (the "cold cathode gas discharge tube") has two electric leads sealed into a glass phial filled with a mixture of helium and hydrogen, the leads being spaced just further apart inside the phial than the discharge gap at a given voltage. On irradiation with ultra-violet light or ionising radiation, the given voltage being applied between the leads, the gas ionises sufficiently for electric discharge to occur between the leads. A photon or particle produces a short burst of current.
Such a switch has utility in being able to detect instantly a very low flux of radiation by virtue of signal amplification in the gas. The output is easily monitored, being in discrete pulses of current.
This type of transducer is manufactured by letting leads into glass tubes in an appropriate atmosphere and sealing the tubes individually to form phials. This form of assembly can be costly, occupies an excessive volume and requires a cathode to anode voltage in the region of 300V.
It is an object of the present invention to provide a light-activated transducer which can be made using mass-production techniques typical of the semiconductor industry and which is susceptible of miniaturisation and a consequent reduction of the voltage it requires in operation.
According to the present invention, there is provided a light-activated transducer comprising a transparent electrically-insulating substrate, an electrode structure applied to a surface of the substrate and supported thereby and comprising an electrode portion apertured for passage therethrough of light incident on a corresponding region of the substrate, a contact pad spaced from the electrode portion, and an electrical feedthrough connecting the electrode portion to the contact pad, an insulator layer adhered on the said surface of the substrate and on the feedthrough, and surrounding the electrode portion while leaving uncovered the contact pad and the electrode portion and the corresponding region of the substrate, a conductive or semiconductive cover sheet adhered on the insulator layer and supported thereby in spaced overlying relationship with the electrode portion and the corresponding region of the substrate and forming therewith, and with the surrounding insulator layer, a sealed cavity, and within the cavity an ionisable gaseous filling.
According, therefore, to another aspect of the invention there is provided a method of making a light-activated transducer which comprises applying to a surface of a transparent electrically-insulating substrate an electrode structure comprising an electrode portion apertured for passage therethrough of light incident on a corresponding region of the substrate, a contact pad spaced from the electrode portion, and an electrical feedthrough connecting the electrode portion to the contact pad,
adhering on the said surface of the substrate and on the feedthrough an insulator layer formed to surround the electrode portion while leaving uncovered the contact pad and the electrode portion and the corresponding region of the substrate,
and, in a suitable gaseous atmosphere, applying a conductive or semiconductive cover sheet on the insulator layer to be adhered and supported thereby in spaced overlying relationship with the electrode portion and the corresponding region of the substrate and forming therewith, and with the surrounding insulator layer, a sealed cavity filled with the said atmosphere as an ionisable gaseous filling.
In a preferred way of carrying out this method according to the invention, after the cover sheet has been applied on the insulator layer the whole assembly is heated and a voltage is applied between the substrate and the cover sheet to promote electrostatic bonding between the insulator layer and the substrate and/or the cover sheet.
The substrate is conveniently glass (such as a borosilicate glass) having significant transmission in the blue or UV, preferably with a thermal expansion coeffi
REFERENCES:
patent: 4761548 (1988-08-01), Laul
patent: 4771168 (1988-09-01), Gundersen et al.
Nuclear Instruments & Methods In Physics Research. vol. A 251, No. 1, Oct. 1986, Amsterdam NL pp. 196-198 R. Bellazzini et al. : "High Resolution Digital Autoradiography of Short and Long Range Emitters Using a Single Step Parallel Plate Chamber".
Review Of Scientific Instruments. vol. 57, No. 9, Sep. 1986, New York US pp. 2234-2237; A. F. Borghesani et al. : "Simple photoelectronic source for swarm experiments in high-density gases".
Daniel Carol D.
Holmes-Siedle Andrew
Rogers Tony W. J.
British Technology Group Limited
Davenport T.
Westin Edward P.
LandOfFree
Light activated transducer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Light activated transducer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Light activated transducer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-794545