US 5,451,747 A · Flexible self-regulating heating pad combination and associated method

Abstract

A flexible, electric heating pad having a self-limiting heating element is provided. The heating element includes a pair of relatively spaced conductors surrounded by a positive temperature coefficient (PTC) material. A layer of electrically insulating material surrounds the PTC material. The PTC material includes a polyolefin resin having a relatively low flexural modulus. The heating element is disposed in a generally serpentine configuration within passages formed in the covering material of the heating pad. The passages are formed by joining together layers of covering material using ultrasonic welding or other suitable ways. The temperature of the heating element is controlled using controller circuit which utilizes a solid state timed interval control circuit. A safety circuit is provided for non-resettably disconnecting electrical power from the heating element if short or open circuit conditions occur therein. A temperature indicator and a variable automatic shutoff circuit are also provided with the controller circuit. A method of making the heating pad is also provided.

Claims66

Dependent claims

A flexible heating pad comprising:

an elongated self-limiting heating element having two relatively spaced conductors surrounded by positive temperature coefficient material;
said positive temperature coefficient material having a density of about 0.928 to 0.958 grams per cubic centimeter and a flexural modulus of about 50,000 to 150,000 psi;
a layer of electrically insulating material surrounding said positive temperature coefficient material,
a power supply cable having one end electrically connected to one end of each said conductor;
connector means on the other end of said power supply cable for connection to a source of electrical power;
plug means for electrically connecting said heating element to said power supply cable;
controller means electrically connected to said heating element for regulating electrical power supplied to said heating element to limit maximum temperature thereof;
flexible covering material forming an outer cover;
said heating element being disposed in a generally serpentine configuration within said outer cover;
and
said flexible covering material being joined together in at least one location to form at least one passage in which said heating element is disposed.

8 more elements

A flexible heating pad comprising:

an elongated self-limiting heating element having two relatively spaced conductors surrounded by positive temperature coefficient material;
said positive temperature coefficient material including a polyethylene resin having a density of about 0.928 to 0.958 grams per cubic centimeter and a flexural modulus of about 50,000 to 150,000 psi;
an electrically insulating layer surrounding said conductors and said positive temperature coefficient material;
plug means for electrically connecting said heating element to a source of electrical power;
flexible covering material forming an outer cover;
said heating element being disposed in a generally serpentine configuration within said outer cover;
and
said flexible covering material being joined together in at least one location to form at least one passage in which said heating element is disposed.

5 more elements

Dependencies are inferred from the claim text.

Flexible self-regulating heating pad combination and associated method

Life of this patent

Flexible self-regulating heating pad combination and associated method

Life of this patent

Abstract

Claims66