| 摘要 |
<p>636,980. Automatic temperature control systems. GENERAL ELECTRIC CO., Ltd., and HILLIARD, A. G. Nov. 21, 1947, No. 30940. [Class 38 (iv)] In order to compensate for variation in ambient temperature in the heating chamber of a piezo-electric crystal in an automatic control system, an oven, represented by the dotted lines, contains electric heating elements 1 in close proximity to the parts R3 and R4 of temperature variable resistors R3+R5 and R4+R6, the parts R5 and R6 being outside the oven and responsive to ambient temperature. The resistors R3+R5 and R4+R6 are connected with fixed resistors R1, R2 in a Wheatstone bridge circuit, the supply being fed in at terminals 2, and the output controlling the heaters 1 being taken off at 3. Thus an increase or decrease in ambient temperature will result in the bridge balancing, after the increase or decrease, with the resistors R3, R4 at a lower or higher temperature than before the change in ambient temperature. Specification 451,141 is referred to.</p> |
