Features of thermistor.Wide-Angle Fresnel Lens manufacture

　　K) The resistance value, B: B value,*t (k) = t (ºc) +273.15. In fact, the B value of thermal resistance is not constant. The change of the change varies from the material composition, and the maximum is even 5K/° C. Therefore, when applying 1 within a large temperature range, there will be some errors with the measured values. Here, if the B value in the formula 1 is calculated as a temperature function as a temperature, the error between the measured values can be reduced. It can be considered as similar.

　　BT = CT2+DT+E, in the upper formula, C, D, E as the constant. In addition, the fluctuations of the B value caused by different production conditions will cause constant E change, but constant C and D remain unchanged. Therefore, when exploring the volume of B values, just consider constant E. Calculation of constant C, D, E, constant C, D, E can be data of 4 points (temperature, resistance) data (T0, R0). (T1, R1). (T2, R2) and (T3, R3),, Calculate through type 3 to 6. First of all, B1, B2, B3 are found according to the resistance values of T0 and T1, T2, T3, and then substituted the following samples.

　　Example of resistance value calculation: Try the resistance value of the resistance at 25 ° C at 25 ° C according to the resistance -temperature characteristic table, and the heating resistance with a B value deviation of 50 (k) at a resistance of 50 ° C to 30 ° C. Essence Step (1) Find constant C, D, E according to the resistance -temperature characteristic table. TO = 25+273.15t1 = 10+273.15T2 = 20+273.15T3 = 30+273.15 (2) Institute of BT = CT2+DT+E+50, find BT. (3) Instead of the value into R = 5EXP {(BT1/T-1/298.15)}, find R. *T: 10+273.15 ～ 30+273.15.

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