SPAN ADJUSTING METHOD OF ELECTRONIC BALANCE AND BALANCE USING SAID METHOD

摘要

PURPOSE:To stabilize the set value of span adjustment by regulating the operation time of a soft timer so that the display value with the weight loaded corresponds to the weight thereof in an electronic balance designed to control the primary integration time of a weight signal with the soft timer. CONSTITUTION:An output signal of a weight sensor A comprising a load cell is amplified with an amplification circuit 2 and fed to a double integration type A/D converter C1. An analog switch 1 of the converter C1 is so arranged to input the reference voltage, amplifier output voltage and ground voltage selectively into an integrator 2 and controlled by a switching signal Sa from a CPU5a and a counting stop signal Sb from a comparator 3. The comparator 3 outputs the signal Sb to the switch 1, a counter 4 and the CPU5a when the output voltage of the integrator 2 reaches the initial integration start voltage. The CPU5a is provided with a soft timer which mainly control the primary integration time of the converter C1 to output a signal Sa at the specified timing and adjusts the operation time by an input means D. Thus, a stable span adjustment can be done.