JPS6419231A - Electric foot warmer - Google Patents

Abstract

PURPOSE:To prevent unnecessary power consumption when a user does not use a foot warmer by a method wherein an infrared sensor is placed in a heating element unit and the changing condition of the infrared rays in the foot warmer is judged by a judging circuit and the temp. of the foot warmer is controlled by a control circuit. CONSTITUTION:An infrared sensor 6 placed in a heating element unit 7 monitors the overall inside of a foot warmer at a center as a detecting visual field A with the start of power conduction and detects the infrared rays of an object changing suddenly just at it crosses the field A as the output of the pyroelectric infrared sensor from its characteristic and this signal is sent to a control circuit 10 through a judging circuit 12 and it is judged whether the condition in the foot warmer is in no sudden changing or constant state at all times. When the signal of the sensor 6 continues suddenly changing condition, it is judged that there is a user desiring to warm himself and the temp. is controlled so as to maintain the temp. set by a user and when the signal of the sensor 6 continues stable condition for a fixed time or more, it is judged that there is no user and control such as reducing the temp. to a value lower than the temp. set by the user or the temp. control such as the cutoff of a heater or a power source is carried out.