Electric heating – Heating devices – With power supply and voltage or current regulation or...
Reexamination Certificate
1999-07-23
2001-05-08
Jeffery, John A. (Department: 3742)
Electric heating
Heating devices
With power supply and voltage or current regulation or...
C219S511000, C337S107000, C337S298000
Reexamination Certificate
active
06229121
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an integrated thermal buckling micro switch, particularly to the integrated thermal buckling micro switch wherein the sensors and actuators are integrated and arranged on a single chip by using micro electromechanical technology.
A conventional thermal buckling switch is usually constructed in a mechanical bimetal structure, wherein two kinds of metal with different thermal expansion coefficients are combined. When the switch is heated to some extent, two contact points of the bi-metal structure will depart from or embrace each other to cut off or drive a circuit.
The thermal buckling switch of mechanical bimetal structure can hardly be pre-set to act at a precise temperature, it is supposed to buckle within a temperature range instead, hence, it only fits systems that require rough temperature control.
In addition, elastic fatigue of a bimetal may come out after repeated expansion and shrinkage to blunt its sensitivity.
Furthermore, the thermal buckling switch of mechanical bimetal structure usually requires extra cooperative mechanical parts that may slow down response of the switch, and besides, its bulky volume and high cost will inevitably reduce its competition capability in the market, and the worst part is that it can hardly be
SUMMARY OF THE INVENTION
This invention is proposed to integrate and dispose the sensors and actuators on a single chip.
Another object of this invention is to provide an integrated thermal buckling micro switch serving as a signal transmission control system with active sensing capability for different operation modes, such as normally open, normally closed or combined according to requirements, wherein critical conditions may be pre-set for switching, and plural actuators can be integrated on a single chip in a matrix array for use in parallel or series connection.
A further object of this invention is to provide an integrated thermal buckling micro switch that can serve as a protector against system overheat.
A furthermore object of this invention is to provide an integrated thermal buckling micro switch with merits of small volume, quick response, least assembly, and easiness for being integrated to ICs.
In order to achieve above objects, an epitaxial chip is etched to form a thin silicon film having a mesa structure, then a thermally sensitive element and a heating element are disposed on the film sequentially. When resistance of the thermally sensitive element becomes greater to produce a signal larger than a pre-set value, the heating element is started to heat that would causes a thermal buckling effect of the thin silicon film, so that a metallic layer of the mesa structure moves to touch the contact points on a baseboard. When the heating element controlled by a control circuit cease to heat, the mesa structure returns back to normal state to thus control switching of an external load.
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patent: 4423401 (1983-12-01), Mueller
patent: 5721525 (1998-02-01), Hofsass
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patent: 5804798 (1998-09-01), Takeda
patent: 5892429 (1999-04-01), Hofsass
patent: 3231136 (1984-02-01), None
patent: 2-226627 (1990-09-01), None
Jang Ruei-Hung
Lo Lieh-Hsi
Tsai Ming-Jye
Bacon & Thomas
Industrial Technology Research Institute
Jeffery John A.
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