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Electric-blanket-control-circuit

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Electric blanket control circuit

Details

Inventors: Crowley, George C.;
Assignee: Northern Electric Company (Chicago, IL)
Primary Examiner: Hickey; Robert J.
Assistant Examiner:
Attorney, Agent or Firm: Clark; George R., Rose; Neil M., Pacocha; John S.

An electric blanket control circuit is provided which includes an overheat protection circuit to detect an overheat condition as well as a fail-safe testing circuit to assure that the electrical components in said overheat protection circuit are properly functioning. A simulation circuit is provided to electrically simulate an overheat condition in the blanket. An on-off switch is provided which will consecutively activate the overheat simulation circuit and then the fail-safe testing circuit so that said circuits are activated each time the electric blanket is turned off by the user.

DETAILED DESCRIPTION The present invention provides an improved electric blanket control circuit which is relatively simple to manufacture and at the same time is completely effective in detecting overheat conditions and furthermore includes fail-safe features which have heretofore not been available.
The invention involves an overheat protection system using a heat sensitive material together with a neon light and light sensitive resistor as disclosed in the aforementioned copending Crowley et al application together with an internal test circuit which is operated each time the blanket is turned on or off or both such that the control components would be tested to make certain that they are operating properly each time the blanket is used.
Specifically, if there is a failure in one of the components in the overheat protection circuit, such malfunction will probably occur with respect to the neon light/light sensitive resistor combination or the relay being used.
Thus, the present invention makes use of an additional test circuit which will simulate an overheat condition and if any of these components are not properly functioning so as to electrically disconnect the blanket heating element, a fuse provided will automatically break down.
This additional test circuit is designed so that it will be automatically activated each time the blanket is used and specifically, in the present embodiment, it will be activated each time the blanket is turned from its "on" to its "off" position.
It is an object of the present invention to provide a more reliable thermostatless overheat protection system for an electric blanket.
It is a further object of the present invention to provide an efficient overheat protection system with a backup fail-safe system.
It is another object of the present invention to provide an internal test circuit to test for component failures every time the subject blanket is used.
It is still a further object of the present invention to simulate electrically an overheat condition in an electric blanket in order to determine that the blanket overheat protection system is properly functioning

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