Circuit Integrity Detection System for Detecting The Integrity of A Sensing Wire in Electrically Heated Textiles

Abstract

A circuit integrity detection system for use in detecting the integrity of a sensing wire in a heating pad wherein the integrity of the sensing wire is determined by first driving one end of the sensing wire with a low voltage electrical test signal from a microcontroller, and then checking whether the test signal is present on the other end of the sensing wire, in order to distinguish the test signal from the standard AC line voltage present on the sensing wire, the electrical test signal is preferably of a different frequency than the standard 50-60 Hz AC line voltage. In one embodiment, the test signal frequency is approximately 30 kHz.

Description

FIELD OF THE INVENTION[0001]The present invention relates to electrically heated textiles hot spot detector and, more particularly, to a system and apparatus for detecting a break in a wire designed to detect hot spots in an electrically heated textile such as a heating pad, electric blanket, electric throw or electric mattress pad.BACKGROUND OF THE INVENTION[0002]In general, an electrically heated textile is a structure having an electric heating element. The heating element may, for example, be heated by resistance via electricity, and may be provided as one or more metallic wires threaded throughout the pad. The shape and size of the metallic wires may vary, and in some cases the wires may actually be small metallic threads. The heating element typically includes a center heating element constructed of metallic wires having Positive Temperature Coefficient (PTC) characteristics. Around the center PTC wire is a layer of Negative Temperature Coefficient (NTC) material. An electric ...

AI Technical Summary

Benefits of technology

The present invention provides a system and apparatus for monitoring the condition of a heating textile sensing wire to determine if there is a break in the wire. This can be done without disengaging the heating circuitry of the textile. The system uses a low-voltage electrical test signal to determine if the sensing wire is intact or broken. The test signal is at a different frequency (e.g. about 30 kHz) than the standard AC line voltage so that it can be distinguished from the standard frequency. The test signal is sent to a comparator which counts the number of transitions over a period of time to determine if the sensing wire is intact or broken. This system provides a safe method for monitoring the condition of the heating textile's sensing wire.

Problems solved by technology

An electric heating pad is typically plugged into a power outlet so that power may be supplied to the heating element, causing the production of heat.

However, a break in the sensing wire may result in the inability of the controller to detect hot spots.

While this may validate the integrity of the sensing wire when the unit is first powered up, it does not work as a continuous “broken sensing wire” detector once the heating pad reaches operating temperatures.

Nor, is it capable of detecting a break in the sensing wire that is not close to the end of the NTC / PTC wire where it connects to the controller connector,

However, it is not possible to know that a break in the sensing wire has occurred.

Specifically hot spot detection is lost between the two wire breaks.

If the sensing wire breaks at any time during use and for any reason, the system will shut down and prevent the use of the product.

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