热重分析仪的称重部分需要去皮调零操作。结合称重部分已有的信号放大电路、模数转换电路和微处理器,基于数模转换器设计了一种去皮、调零电路,采用文中提出的估值-逐位逼近算法调整称重电路的零点,实现大范围快速去皮调零。实际测量结果显示:对超过所选量程的皮重能精确去皮,去皮调零时间比折半法减少了一半。
It is necessary to eliminate tare weight and adjust zero for the weighing unit of thermal gravimetric analyzer. Using the signal amplifier circuit, ADC and microprocessor of a normal weighing unit, this paper designed a novel circuit with DAC to eliminate tare and adjust zero, and presented an estimated- successive approximation to achieve the aim of large range and fast adjustment. The measure results show that an accurate adjustment can be realized while the tare largely exceeds the selected measurement range and the adjusting time is half of the dimidiate method.