US Patent: 3,553,647
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| Apparatus for Numerical Signaling of Positions, Including Digital to Analog Converter
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Patentee:
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| Thomas B. Bullock (exact or similar names) - Fond Du Lac, Fond Du Lac County, WI |
| Manufacturer: |
| Not known to have been produced |
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Patent Dates:
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| Applied: |
Apr. 21, 1967 |
| Granted: |
Jan. 05, 1971 |
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Joel Havens
"Vintage Machinery" entry for Giddings & Lewis Manufacturing Co.
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Description: |
| Abstract:
Apparatus for producing digital signals which numerically represent at all times the position of a movable element as it moves to different positions along its path oftravel. The digital signals in the form of bi-level voltages are produced in a multidecade reversible counter to represent the position numerically in binary coded decimalnotation. These signals are supplied to a digital-to-analog converter whose analog output, corresponding to the represented position, is supplied to a resolver type transducer mechanically coupled to the element. The transducer produces a discrepancy signal representing the sense and extent of any difference between the numerically represented position and the actual position of the element. So long as the discrepancy signal exists, pulse producing means are enabled to supply pulses to the counter so as to correctively change the number signaled by the counter until the difference and the discrepancy signal are reduced substantially to zero. The closed loop correction is very rapid, so for practical purposes the number digitally signaled by the counter always represents the actual position of the movable element. The digital-to-analog converter here disclosed is the type which produces sine and cosine function signals for excitation of a resolver type transducer. This converter is characterized by cross-coupling of the outputs and inputs of two algebraic combining devices such as operational amplifiers, by static switching means responsive to input signals digitally representing a changeable number, and by simple resistors selectively rendered effective to produce AC signals proportional to sine and cosine functions of the sums of angles corresponding to higher and lower order portions of the changeable number.
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