| 摘要 |
<p>1,079,056. Measuring temperature electrically. DECCA Ltd. Sept.13, 1965 [Sept. 28, 1964], No. 39449/64. Heading G1N. Frequency variations of a resonant circuit element such as an LC network, 40, Fig. 1, or a crystal represented thereby, which variations are proportional to the square of the temperature change from a datum value, are corrected by generating by means of bridges 14, 24 a signal the amplitude of which is proportional to the square of the temperature change, and by using this signal to control the value of a reactance 36 connected across the circuit element 40. The bridges may be Wheatstone bridges, or may each consist simply of a pair of resistors of different thermal coefficients series connected across an a.c. source 10. The bridges are balanced at the datum temperature, which would be the turnover temperature of the crystal, 40. The output of the first bridge 14 energizes the second bridge 24 via a transformer 20, to give a signal dependent upon the square of the temperature change, this being amplified at 30 and rectified at 32 to control the variable reactance 36, which may be a variable capacity diode. The square law relation may be modified by rectifying at 38 the signal from an extra secondary winding 22 on the transformer 20, and supplying this also to the variable reactance 36.</p> |
