| 摘要 |
An electronic weighing apparatus, comprising: a scale mechanism having a weighing plate for placing an article being weighed, a slit plate provided to be moved associated with the weight of said article on said weighing plate and having a series of slit equally spaced in the moving direction, a light source provided at one side of said slit plate, a photodetector provided at the other side of said slit plate opposite to said light source, whereby a pulse train is generated from said photodetector the number of which pulses is associated with the movement of the slit plate and thus with the weight of said article, a counter for counting the number of pulses of said pulse train for providing the weight value, a display for displaying the weight value in said counter, a zero point detecting circuit for detecting the weighing plate having returned to the zero point, a balanced state detecting circuit for detecting said weighing plate having reached a balanced state, a measurement start switch, a first AND gate receiving the output from said measurement start switch, the output from said zero point detecting circuit and the output from said balanced state detecting circuit for providing an enabling signal, a tare weight deduction instructing switch, a second AND gate receiving the output from said tare weight deduction instructing switch, the output from said balanced state detecting circuit and a signal indicative of the weight value in the counter being plus, a tare weight deduction storing flip-flop responsive to the output from said second AND gate to be set and responsive to said enabling signal from said first AND gate to be reset, and means responsive to said set output from said flip-flop for resetting the tare weight value in the counter obtained for said tare, thereby to enable measurement of only the net weight of said thing. |
