Abstract: A key device, as used in a keyboard, comprises(a) a hinge,(b) a key tab projecting in one direction relative to the hinge, and connected with the hinge,(c) a pusher projecting in another direction relative to the hinge, and connected with the hinge, and(d) a spring arranged to be deflected when the key tab is downwardly depressed about the hinge axis, to resist such depression.

Abstract: Electronic scale apparatus includes a face transducer having a first analog output; digital to analog converter circuitry having a second output; a first differential amplifier to receive such outputs and to produce a third output; and a second differential amplifier to receive the third output and output of the converter circuitry to produce another output. A major portion of the weight of the object being weighed is determined at the output of the first differential amplifier (i.e. a coarse measurement). The remaining portion or difference is then amplified and balanced out at the second differential amplifier, enabling accurate determination of weight and driving of the digital to analog converter in feed-back mode.