| 摘要 |
Many electrical appliances and tools which incorporate an electric heating element (such as flat irons, hair curlers and soldering irons) are a fire hazard when left unattended. Unattended operation, intentional or not, is also wasteful of energy. An electronic appliance use detector and timer (UDT) circuit (1) is provided to be used as a separate accessory to (Fig. 2) or as an integral part of (Fig. 3) an electric heating appliance (49) for monitoring the use or activity of the appliance (49) and for establishing a selectively variable time interval during which the appliance (49) must be used to avoid power shut-off. An electronic clock counter (15) establishes the period during which appliance activity must be detected by appliance use detector (2) to prevent a power shut-down sequence from being initiated. The use detector (2) can consist of various devices for detecting that the appliance (49) has been used, either by sensing motion of the appliance (49) or the grasping or handling the appliance (49) by the user, and may take the form of a handle switch, piezoelectric motion detector, strain gauge, accelerometer, or a photoelectric or magnetic sensor. The signal from the use detector (2) automatically resets UDT circuit (1) each time the appliance (49) is used. The UDT circuit (1) includes an audible alarm (55) and visual indicator (54) to warn the user of an impending power turn-off unless use of the appliance (49) is detected by use detector (2), so that the user, upon noting the warning, may momentarily utilize the appliance (49) thus resetting the UDT circuit (1). |
