| 摘要 |
<p>1,156,935. Automatic temperature control. L. A. KELEMEN. Sept. 15, 1966, No.41295/66. Heading G3R. An arrangement for controlling the temperature of an electrically heated article comprises means whereby the main automatic control circuit can be short-circuited for a predetermined time after the article has been switched on in order to allow the article to reach its operating temperature rapidly before the main automatic control circuit becomes operative. Closure of a switch 3 allows the heating element 4 of an electric blanket 5 to be supplied from a source 1, 2 by way of an indicating lamp 9, normally closed contacts of a bi-metal switch 8 and the heating element 10 thereof. After a predetermined time the bi-metal element 11 of the switch 8 is heated sufficiently to open the contact whereafter the heating element 4 of the blanket is supplied by way of a device such as a thyristor 13. During normal operation deviation of the temperature of the blanket 5 from normal causes a signal to be developed in a bridge circuit which includes the heating element 10, the blanket heating element 4 and resistors 18-20. This signal is applied to the primary winding 21 of a transformer 14 thus to control the thyristor 13 by way of a transistor 23 and a bi-directionally conducting device such as a disc 12. The resistor 18 is variable to set the desired blanket temperature and a lamp 28 indicates the blanket receiving a supply by way of the thyristor 13.</p> |
