초록 ▼

A heated bedcover containing an electrical heating element therein is provided with an integrated solid state control circuit which functions providing control over the heating element both for comfort control so as to maintain a desired heat output from the heating element and to also provide prote

A heated bedcover containing an electrical heating element therein is provided with an integrated solid state control circuit which functions providing control over the heating element both for comfort control so as to maintain a desired heat output from the heating element and to also provide protection against overheating conditions in the blanket.

대표청구항 ▼

An electrical heating apparatus comprising: a bedcover; electrical heating means in said bedcover for generating heat upon flow of alternating electrical current therethrough; and control means associated with said electrical heating means and operable both (1) for regulating the temperature of said

An electrical heating apparatus comprising: a bedcover; electrical heating means in said bedcover for generating heat upon flow of alternating electrical current therethrough; and control means associated with said electrical heating means and operable both (1) for regulating the temperature of said bedcover to a level set by the user and in response to changes in the ambient temperature and (2) for providing protection against an overheating condition in said bedcover, said control means comprising: (a) a pair of gate controlled bidirectional semiconductor switches electrically connected to one another in series and in front-to-front orientation and also connected in series with said electrical heating means for controlling the passage of portions of both half cycles of an alternating electrical current so as to modulate the power delivered to said electrical heating means in response to a low current gating signal whose phase can be varied in relation to the alternating electrical current applied to said pair of semiconductor switches; (b) means capacitively coupling the gates of said pair of semiconductor switches to each other; (c) means electrically interconnecting the gate of each one of said semiconductor switches to the back of the other one of said semiconductor switches; (d) positive temperature coefficient resistance means for sensing changes in ambient temperature above and below a predetermined temperature which is set by a user for comfort, said positive temperature coefficient resistance means being electrically connected by said means (c) in series with the gate of one of said semiconductor switches and the back of the other to allow phase control of said pair of semiconductor switches in response to changes in ambient temperature sensed by said positive temperature coefficient resistance means; and (e) temperature sensitive resistance means in said bedcover for sensing the occurrence of an overheating condition in the bedcover, said temperature sensitive resistance means being electrically connected with the gate of at least one of said pair of semiconductor switches for triggering the switches to a nonconductive state in response to a predetermined change in the resistance of said temperature sensitive resistance means in said bedcover resulting from the occurrence of an overheating condition so that the electrical current to said electrical heating means is interrupted.