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US 4,143,364 AGranted
Optical displacement measuring system
AssigneePitney Bowes Inc.
InventorDaniel F. Dlugos
Life of this patent
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AssigneePitney Bowes Inc.
InventorDaniel F. Dlugos
Estimating the term…
A system for processing cyclic signal pairs generated by an optical transducer to provide an accurate measurement of the displacement of one member with respect to a reference is suitable for determining weight by measuring spring scale tare deflection. The system includes a pair of comparator Schmitt trigger circuits for shaping pulse waveform signals. The pulse signals are processed by fully clocked digital circuits including edge discriminators to generate multiple count pulses which are processed by combination logic for direction determination. Further processing includes sign determination (positive-negative) and zero identification circuits to provide up and down pulses which are filtered and fed to up/down counter stages. Counter stage information is decoded for feedback control and processing logic indication. The zero identification circuit facilitates an unambiguous zero reference indication by skipping one count at zero to provide a display sign change indication on either side of zero prior to incrementing display counts to better define true zero as an edge or line between successive displays rather than as a zone. In an alternate embodiment, zero transition indicators are provided by feeding the count pulses directly to an up/down counter and utilizing the most significant counter bit to invert the counter outputs upon a transition through actual zero.
In an analog to digital conversion system for measuring the change of a bidirectionally variable parameter whose change is to be measured with respect to a reference, the system comprising means generating a pair of phase displaced cyclic waveforms as a function of the change to be measured, processing means receiving the waveforms and in response thereto providing a pulse count signal, means receiving the pulse count signal and in response thereto providing value indications of the change with respect to the reference, and means for receiving the value indications of the change with respect to the reference and in response thereto for visually displaying the change of the bidirectionally variable parameter with respect to the reference, the improvement comprising means coupled to the count pulse signal and adapted to block a single pulse of the signal from the receiving means in response to an initial incrementation of the variation from the reference in either one of two directions, whereby the value indication at the reference corresponds to a transition between successive value indications of initial change from the reference in each direction to facilitate calibration of the system through visual recognition of the reference as a transition point rather than a zone.
In a spring scale adapted to measure the weight of a load as a function of the deflection from a fixed reference of a tare adapted to carry the load, the scale comprising means operatively interconnecting the scale tare and the reference, means adapted to generate an optical cyclic pattern, the generating means including means varying the pattern as a function of the scale tare deflection from a no load position, optoelectronic transducer means, the pattern being projected upon the transducer means, the transducer means generating a pair of phase displaced cyclic waveforms as a function of the deflection of the tare, processing means receiving the cyclic waveforms and in response thereto providing a pulse count signal indicative of movement of the tare in response to the load, means receiving the pulse count signal and in response thereto providing value signals indicative of the measure of tare movement from the reference, and means for receiving the value signals indicative of the measure of the scale tare deflection from the reference and in response thereto for visually displaying the tare deflection from the reference, the improvement comprising means coupled to the count pulse signal and adapted to block a pulse of the signal from the receiving means in response to an initial deflection of the tare from the reference, whereby the value signal at the reference corresponds to a transition between successive value signals of deflection from the reference to facilitate scale calibration throught visual recognition of the reference as a transition rather than a zone.
Dependencies are inferred from the claim text.