| 摘要 |
<p>1,137,567. Automatic control of temperature. GENERAL ELECTRIC CO. Sept.23, 1966 |Dec.30, 1965], No. 42509/66. Heading G3R. Control apparatus for an electric blanket 10 having a heater element 26 comprises a device 27 sensitive to the temperature of the blanket, the device having a pair of conductors 28, 29 separated by a layer 30 the resistance of which varies negatively with temperature, the apparatus further including a cyclically operated switch 40 effective to maintain the blanket at a predetermined temperature and a switch 42 which provides ambient temperature compensation. Closure of a switch 33 completes a circuit through contacts 35, 39 of switch 40 and contacts 48, 49 to switch 42 to energize the heater 26 of the blanket 10. A further circuit is made which includes heater 48, conductor 28, heater 44 and conductor 29. Whilst the blanket temperature is below a predetermined value there is little current flow across the layer 30 between the conductors 28, 29 and the effect of the heaters 43, 44 on the bi-metal elements 32, 36 is such that the contacts 35, 39 remain closed with the heater 26 of the blanket energized. Above the predetermined blanket temperature the resistance of the layer 30 assumes such a value that a certain amount of current flows between the conductors 28, 29 across the layer 30. This current flows through the heater 43 whereby the bi-metal element 32 moves to open contacts 35, 39 to de-energize the blanket heater 10. A control knob 51 is provided to allow the user to control the operation of the ambient temperature compensating switch 42.</p> |
