ELECTRICALLY HEATED BEDCOVER WITH THERMOSTATLESS OVERHEAT PROTECTION CIRCUIT AND SEPARATE COMFORT CONTROL

• US 3,683,151 A
• Filed: 02/26/1971
• Issued: 08/08/1972
• Est. Priority Date: 02/26/1971
• Status: Expired due to Term

• Current Assignee: Field Crest Cannon Incorporated
• Original Assignee: Edwin R. Mills, Ernest L. Elmore
• Inventors: Edwin, R. Mills, Ernest, L. Elmore
• Primary Examiner(s): C. L. Albritton
• Application Number:
  US05/119,104
• Time in Patent Office: 529 Days
• Field of Search: 219/211,212,527,529,549,501 128/379,402 5/343
• US Class Current: 219/212
• CPC Class Codes: G05D 23/1909 whose output amplitude can only take two discrete values
• CPC Class Codes: G05D 23/24 the sensing element having a resistance varying with temperature, e.g. a thermistor
• CPC Class Codes: H05B 2203/003 using serpentine layout
• CPC Class Codes: H05B 2203/036 Heaters specially adapted for garment heating
• CPC Class Codes: H05B 3/342 heaters used in textiles

Abstract

An electrically heated bedcover wherein the generation of heat upon flow of electrical current through an electrical heating element is controlled, in response to variations in ambient temperature affecting the comfort of a user of the bedcover, by a comfort control circuit while continuance of any unsafe localized overheat condition is prevented by an overheat protection circuit which is physically separate from the comfort control circuit. By such separation, an electrically heated bedcover having a gate controlled semiconductor switch included in a thermostatless overheat protection circuit is adapted for cooperation with a comfort control circuit which also has utility with other types of electrically heated bedcovers.

Claims

1. An electrically heated bedcover comprising:

a bedcover, electrical heating means in said bedcover for generating heat upon flow of electrical current therethrough, comfort control means separate from said bedcover and operable between electrically conductive and non-conductive states for controlling conduction of alternating electrical current therethrough, said comfort control means including compensating means responsive to ambient temperature conditions for increasing conduction of alternating electrical current as ambient temperature decreases, elongate two conductor cable means extending between and electrically connecting said heating means and said comfort control means for directing electrical current conducted through said comfort control means to flow through said heating means, said cable means having a terminal end remote from said comfort control means which is adapted for connection with said heating means, and overheat protection means electrically connected between said remote end of said cable means and said heating means for modulating the average power of electrical current flowing therethrough, said overheat protection means including sensing means in said bedcover for detecting the occurrence of an overheat condition and switch means located at said bedcover for normally conducting substantially full cycles of alternating electrical current and for responding to the occurrence of an overheat condition by conducting significantly less than full cycles of alternating electrical current.

2. An electrically heated bedcover according to claim 1 further comprising mating plug means for separably connecting said cable means and said heating means said plug means including a first plug at a terminal end of said cable means and a second plug secured to said bedcover, and further wherein said switch means of said overheat protection means is disposed at said plug means.

3. An electrically heated bedcover according to claim 2 wherein said switch means is mounted within said second plug.

4. An electrically heated bedcover according to claim 1 wherein said switch means of said overheat protection means is mounted within said bedcover.

5. An electrically heated bedcover according to claim 1 wherein said compensating means comprises a bimetallic thermostatic switch electrically connected in series with one conductor of said cable means and compensating heater means thermally couples to said thermostatic switch for thermally biasing the same.

6. An electrically heated bedcover according to claim 1 wherein said switch means of said overheat protection means is a gate controlled semiconductor switch and said sensing means comprises temperature sensitive electrically conductive means disposed in said bedcover in heat exchange relation with said heating means and electrically connected with said semiconductor switch for controlling the portion of a cycle of alternating electrical current conducted therethrough.

7. An electrically heated bedcover comprising:

a blanket, electrical heating means in said blanket for generating heat upon flow of electrical current therethrough, a control housing separate form said blanket, ambient temperature responsive control means in said housing for responding to variations in room temperature affecting the comfort of a user of the bedcover, said control means including switch means operable between electrically conductive and non-conductive states for controlling conduction of electrical current through said control means, cable means extending between said housing and said blanket and electrically connecting said heating means in series with said switch means, said cable means having a terminal end remote from said housing which is adapted for connection with said heating means, and overheat protection means for reducing the average power delivered by electrical current flowing through said heating means, said overheat protection means including gate controlled semiconductor switch means located at said blanket and electrically connected between said remote end of said cable means and said heating means and sensing means in said blanket and operatively connected to said semiconductor switch means for detecting the occurrence of an overheat condition and for modulating conductance of current through said semiconductor switch means in the event an overheat condition occurs.

8. An electrically heated bedcover comprising:

a textile blanket shell, electrical heating means in said blanket shell for generating heat upon flow of electrical current therethrough, ambient temperature responsive control means spaced from said blanket shell for responding to variations in room temperature affecting the comfort of a user of the bedcover, saId control means including switch means operable between electrically conductive and non-conductive states for controlling conduction of electrical current through aid control means, cable means extending between said control means and said blanket shell and electrically connecting said heating means in series with said switch means, said cable means having a terminal end remote from said control means which is adapted for connection with said heating means, and overheat protection means for reducing the average power delivered by electrical current flowing through said heating means, said overheat protection means including gate controlled semiconductor switch means located intermediate said blanket shell and said remote end of said cable means and electrically connected in series with said heating means and further including sensing means in said blanket shell and operatively connected to said semiconductor switch means for detecting the occurrence of an overheat condition and for modulating conductance of current through said semiconductor switch means in the event an overheat condition occurs.