Electronic weighing apparatus

摘要

An electronic weighing apparatus includes a scale mechanism having a weighing plate for placing thereon an article to be weighed in a package the latter constitutes a tare weight. A slit plate is movably associated with the weight of said article on said weighing plate and has a series of slots equally spaced in the moving direction. A light source is provided at one side of said slit plate. A photodetector is 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 pulses in the pulse train 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 provides the weight value and a display displays the weight value in said counter. A balanced state detecting circuit detects that the weighing plate has reached a balanced state. A tare weight deduction instructing switch is manually operated and cooperates with, an AND gate receiving the output from said tare weight deduction instructing switch and the output from said balanced state detecting circuit. Resetting means are responsive to the output from said AND gate for resetting the tare weight value in the counter obtained for said tare, thereby to enable measurement of only the net weight of the article proper.