Abstract: An electromagnetic feeder drive control apparatus includes a drive control circuit composed of a microcomputer for producing a timing signal to control the on/off timing of a switching element on the basis of a signal produced by a sensor upon sensing that the power supply voltage has crossed a value of zero. A photocoupler is interposed between the sensor and the drive control circuit, and between the drive control circuit and the switching element.

Abstract: A load sensor includes a scale cell for producing an output signal corresponding to the weight of an article, and a dummy cell, provided near the scale cell, for producing a noise signal output ascribable to floor vibration. A correcting circuit extracts a signal proportional to a DC component contained in the output signal of the scale cell and, on the basis of the extracted signal, corrects the output signal of the dummy cell to the noise level of a floor vibration component of the scale cell. The corrected dummy cell noise signal is added in opposite-phase relation to the scale cell output signal, so that the floor vibration noise contained in the scale cell output signal is cancelled out by the corrected noise signal of the dummy cell.

Abstract: A load sensor includes a fixed rigid portion, a movable rigid portion spaced from the fixed rigid portion and adapted to receive an applied load, and a shear-deformable member provided between the two rigid portions. The shear-deformable portion is provided with a transmission and a reception transducer constituting an elastic surface-wave oscillator. When a load is applied to the movable rigid portion, weight is sensed based on a deviation in the oscillation frequency of the elastic surface-wave oscillator. The fixed and movable rigid portions, as well as upper and lower beams interconnecting these portions, constitute a load-sensitive element. The latter has a side face which is closed off by a pliable membrane for sealing the shear-deformable element disposed within the load-sensitivie element. Alternatively, a corrugated bellows is connected across the fixed and movable rigid portions to seal the shear-deformable member within the bellows.

Abstract: A double-integrating A/D converter in which an integrator output voltage, produced by integrating an analog signal input thereto, is reverse-integrated in accordance with a reference voltage having a polarity opposite to that of the analog signal. The time required for the reverse integration is measured in the form of a pulse count by means of a counter. A microcomputer for controlling the counter and a switch which selects the input to the integrator are provided with a software timer function so that the integrating interval of the analog input signal is set at will. The microcomputer also is capable of calculating a digital value, which corresponds to the analog signal, from a count recorded in the counter and from an overflow value indicated by an overflow signal generated by the counter. The signal converted by the A/D converter is capable of being applied to the weighing section of an electronic weigher.

Abstract: There is provided a system for adjusting the span of an electronic scale having a double-integrating A/D converter for converting a weight signal into a digital signal. The double-integrating A/D converter has a software-implemented timer for controlling a primary integrating time. The operation time of the software-implemented timer is adjusted linearly or in steps so that a digital value at the time a weight is placed on the scalepan of the scale will correspond to the weight. The adjustment of the operation time of the software-implemented timer is utilized to adjust the differences between gravitational accelerations corresponding to different weights in geographical areas on the earth.

Abstract: A differential amplifier which incorporates at its preceding stage resistances and condensers combined with each other and serving as a low-pass filter, thereby omitting a conventional low-pass filter separate from a differential amplifier provided at a weight detection circuit for a load cell weighing scale or other detection circuit.

Abstract: A weight detection circuit for a load cell scale which connects an operational amplifier directly to an-output of a bridge circuit of a load cell so as to simplify a conventional differential amplifier, thereby enabling simplification of the overall weight detection circuit to result in a reduction in manufacturing cost. Furthermore, a bias resistance is connected directly to the bridge circuit for the load cell thereby also to simplify the bias circuit to lead to a further reduction in manufacturing cost.