US 4,381,501 A · Encoding apparatus utilizing acoustic waves of controlled initial polarity

Abstract

Polarity of transducer signals is controlled in encoding apparatus of the acoustic rod type, e.g. where key-actuated strikers impact an acoustic bar having a transducer at each end of the bar, the impact giving rise to divergent acoustic waves. The wave fronts of these acoustic waves are sensed by the transducers, the output signals of which are used to produce codes corresponding to the actuated key. By varying the shape of the bar at each point of impact, the polarity of the wave fronts can be controlled so as to distinguish the operation of adjacent strikers and thus provide correspondingly coded outputs or can be combined with elapsed time sensing systems to afford more reliable encoding even in the presence of lot-to-lot differences in the bar material's acoustic wave properties--differences aggravated by temperature changes.

Claims29

Dependent claims

In an encoding apparatus of the acoustic type comprising an acoustic member, means for inducing acoustic energy within the member in the form of a wave traveling within the member, and means spaced from the inducing means and operatively connected to the member for sensing the wave;

the improvement comprising first control means on said member cooperating with said inducing means and providing a wave having a wave front of particular polarity, second control means on said member cooperating with said inducing means and providing a wave having an opposite polarity for said wave front, and means connected to said sensing means and responsive to the polarity of the wave front for providing first code information on sensing of said particular polarity and second code information on sensing of said opposite polarity, said first code indicating cooperation of said inducing means with said first control means, whereas said second code indicates cooperation thereof with said second control means.

In an encoding keyboard of the type having a plurality of actuatable keys, a member for transmitting acoustic energy, a plurality of spaced devices for inducing acoustic energy within said member, each said inducing device being operable in response to actuation of a related one of the plurality of keys, the acoustic energy forming separate wave fronts traveling in diverging directions at an intrinsic velocity subject to variations;

transducers operatively connected to the member for converting the wave fronts into signals with an elapsed time therebetween as determined by the intrinsic velocity, and time-responsive units connected to the transducers for generating from the elapsed time a code representative of the key actuated, the improvement comprising:
first control means on said member cooperating with a said inducing device related to a first of said keys and providng a particular polarity to one of said wave fronts, second control means on said member cooperating with a said inducing device related to a second of said keys and providing an opposite polarity to the one wave front, and means sensing the polarity of the one wave front and operable in response thereto for providing from said elapsed time a first code on sensing said particular polarity and a second code on sensing said opposite polarity, whereby said first code accurately indicates actuation of said first key and said second code accurately indicates actuation of said second key in spite of said variations in the intrinsic velocity.

A method for generating a code representative of a selected one of a plurality of mechanical motions comprising the steps of:

(a) shaping a member into a plurality of differently shaped portions respectively corresponding to individual ones of said plurality of mechanical motions,
(b) inducing vibratory energy within said member in response to a selected one of the mechanical motions, the corresponding shape of the member controlling the induced vibratory energy to form a wave front having a selected one of two polarities,
(c) sensing the polarity of the wave front within said member, and
(d) providing a code output identifying the selected motion in dependence upon the polarity sensed.

1 more element

Dependencies are inferred from the claim text.

Encoding apparatus utilizing acoustic waves of controlled initial polarity

Life of this patent

Encoding apparatus utilizing acoustic waves of controlled initial polarity

Life of this patent

Abstract

Claims29