SHAFT ENCODER FOR APPARATUS HAVING LUMINOUS PHOSPHOR SOURCE

• US 3,815,126 A
• Filed: 03/01/1971
• Issued: 06/04/1974
• Est. Priority Date: 03/01/1971
• Status: Expired due to Term

• Current Assignee: James E. Batz
• Original Assignee: James E. Batz
• Inventors: Batz, James E.
• Primary Examiner(s): Sloyan, Thomas J.
• Application Number:
  US05/119,588
• Time in Patent Office: 1,191 Days
• Field of Search: 340/347P 250/71R,16R,16S,219DD
• US Class Current: 341/1
• CPC Class Codes: H03M 1/00 Analogue/digital conversion; Digital/analogue conversion conversion of analogue values to or from differential modulation H03M3/00
• CPC Class Codes: H03M 1/22 pattern-reading type

Abstract

An analog-to-digital converter for converting angular positional information of a shaft associated with a meter dial register into binary coded outputs includes a non-contacting encoder having a code member with a plurality of photo resistive sense elements and a luminous phosphor source mounted for rotation by the shaft in enabling relationship with the code member providing radiant energy for energizing the sense elements selectively as the source rotates with the shaft relative to the sense elements to provide coded output signals representing ten digit positions and ten interdigital positions of the shaft; output decoding circuits provide round off of interdigital position codes and convert the coded signals to a two-out-of-five code.

Claims

1. In an analog-to-digital converter for providing a different set of output signals for each of a plurality of predetermined angular positions of a shaft, an encoder including a code disc having a surface covered with a photoresistive material and a plurality of pairs of conductors disposed on said photoresistive material and extending from the periphery of the code disc toward tHe center of said code disc in a spaced relationship forming a gap therebetween thereby exposing a continuous narrow strip of the photoresistive material in said gap such that each pair of conductors defines a separate photoresistive sense element, each of said sense elements having a first resistance when energized and a second resistance when unenergized, source means mounted for rotation by said shaft in enabling relationship with said sense elements including radiant energy means having a phosphor stimulated by radiations from a radioactive element to emit light for selectively energizing different ones of said sense elements as a function of different angular positions of said shaft, and output means controlled by said sense elements to provide a different one of said sets of output signals for each predetermined angular position of said shaft, said code disc having a plurality of discrete areas each of which represents a predetermined position of said shaft, and regions intermediate each pair of adjacent discrete areas, the conductors of each of said sense elements having an intermediate portion disposed on said code disc in a different one of said discrete areas and projections extending from a corresponding intermediate portion into intermediate regions adjacent the corresponding discrete area such that the intermediate regions between an adjacent pair of sense elements include the projections of conductors of a pair of adjacent sense elements and the photoresistive material exposed therebetween to permit such pair of adjacent sense elements to be energized concurrently whenever said source overlies the portions of sense elements disposed in a common intermediate region whereby first and second sets of output signals representing two angular positions of said shaft are provided over said output means.

2. A converter as set forth in claim 1 wherein said source means include means for directing light emitted by said phosphor towards the portion of the sense elements immediately underlying said source means.

3. In an analog-to-digital converter for providing a different set of output signals for each of a plurality of predetermined angular positions of a shaft, an encoder including a code disc having a surface covered with a photoresistive material and a plurality of pairs of conductors disposed on said photoresistive material the conductors of each pair extending generally over a radial portion of the code disc from the periphery toward the center of the code disc in a spaced relationship forming a gap therebetween thereby exposing a continuous narrow strip of the photoresistive material in said gap such that each conductor pair defines a separate sense element, each conductor of a given pair of conductors including a plurality of concentric arcuate conductor segments interconnected to form a continuous conductive path extending over said radial portion of said code disc to thereby maximize the length of the strip of photoresistive material exposed therebetween, each sense element having a first resistance when energized and a second resistance when unenergized, energizing means mounted for rotation by said shaft in an enabling relationship with said sense elements, said energizing means including radiant energy means for providing radiant energy for selectively energizing different ones of said sense elements as a function of different positions of said shaft, and output means controlled by said sense elements to provide a different one of said sets of output signals for each predetermined angular position of said shaft.

4. A converter as set forth in claim 3 wherein said code disc includes a separate sense element for each of said predetermined shaft positions, said energizing means being effective to energize one of said sense elements whenever said shaft is at one of said predetermined positions and to energize a pair of adjacent sense elements whenever said shaft is at a position intermediate a first and a second one of said predetermined positions.

5. A converter as set forth in claim 4 wherein said output means includes output switching means for each sense element operable to provide a first output signal whenever an associated sense element is energized and operable to provide a second output signal whenever an associated sense element is unenergized, one of said output switching means being operable to provide said first output signal whenever said shaft is at one of said predetermined positions and a pair of said output switching means being operable to provide said first output signal whenever said shaft is at a position intermediate a first and a second one of said predetermined positions.

6. A converter as set forth in claim 3 wherein said radiant energy means includes a radioactive element and a phosphor stimulated by radiations from said radioactive element to emit light.

7. In an analog-to-digital converter for providing a different set of output signals for each of a plurality of angular positions of a shaft, an encoder including a code disc having a surface covered with a photoresistive material and a plurality of pairs of conductors disposed on said photoresistive material and extending from the periphery of the code disc toward the center of the code disc in a spaced relationship forming a gap therebetween thereby exposing a continuous narrow strip of the photoresistive material in the gap such that each of said conductor pairs defines a separate photoresistive sense element, each of said sense elements providing a first resistance when energized and a second resistance when unergized, energizing means mounted for rotation by said shaft relative to said sense elements in a spaced overlying relationship with said sense elements and including source means and support means for locating said source means to define an enabling zone for said sense elements, said source means having a radiant energy means including radioactive element and phosphor stimulated by said radioactive element to emit light for selectively energizing different ones of said sense elements as a function of different angular positions of said shaft, and output means including a plurality of output circuits, one for each sense element, each output circuit providing a first output whenever an associated sense element is energized and a second output whenever an associated sense element is unenergized.

8. A converter as set forth in claim 7 wherein said support means comprises a hollow box-like structure of an opaque material having inner baffles defining a plurality of longitudinal U-shaped channels in said structure extending parallel to and opening toward said code disc, said radiant energy means being disposed at the bases of said channels.

9. A converter as set forth in claim 8 wherein said radiant energy means comprises a mixture of said radioactive element and said phosphor, coating the bases of said channels.

10. A converter as set forth in claim 7 wherein each of said output circuits includes switching means connected to an associated sense element, disabled when an associated sense element is energized to provide said first output signal and enabled when an associated sense element is unenergized to provide said second output signal.

11. A converter as set forth in claim 7 wherein said code disc includes 10 sense elements and said converter provides 20 different sets of output signals representing an unambiguous coding for 10 angular positions of said shaft.

12. A converter as set forth in claim 7 wherein said source means includes a transparent capsule having an inner surface coated with said phosphor and containing a radioactive element in gaseous form for stimulating said phosphor.

13. A converter as set forth in claim 12 wherein said support means include a pair of disc-shaped members mounted for rotation by said shaft and enclosing said capsule, one of said disc members having an aperture adjacent said code member to permit light emitted from said phosphor to be directed toward the pOrtion of the code member adjacent said aperture as said support means are rotated by said shaft.

14. In an analog-to-digital converter for providing a different set of output signals for each of a plurality of predetermined angular positions of a shaft, an encoder including a code disc having a plurality of discrete areas, each of which corresponds to a different predetermined position of the shaft, and regions intermediate each pair of adjacent discrete areas, a plurality of photosensitive sense elements, including a separate photosensitive sense element for each of said predetermined positions disposed on said code disc in a corresponding discrete area, the sense element for each discrete area including photoresistive material disposed on a surface of said code disc in the discrete area and a pair of conductors including a first conductor disposed on a first portion of the photo-resistive material and extending radially from adjacent the center of the disc to the periphery of the disc over a portion of the discrete area and a second conductor having a conductor portion disposed on a second portion of said photoresistive material and extending radially from adjacent the center of the disc to the periphery of the disc in a spaced relationship with said first conductor, forming a gap therebetween thereby exposing a continuous narrow strip of photoresistive material in said gap, and source means, including a phosphor radioactively energized to emit light, mounted for rotation by said shaft relative to said sense elements for selectively energizing the sense element portions which are disposed adjacent thereto, and output means controlled by said sense elements to provide a different one of said sets of output signals for each predetermined angular position of said shaft.

15. A converter as set forth in claim 14 wherein the source means includes support means for locating said source to define an enabling zone for said sense elements to enable one of said sense elements whenever said shaft is at one of said predetermined positions and to enable an adjacent pair of said sense elements whenever said source is at a position intermediate each adjacent pair of said predetermined positions.

16. In an analog-to-digital converter for providing a different set of output signals for each of a plurality of predetermined angular positions of a shaft, an encoder including a code disc having a plurality of discrete areas, each of which corresponds to a different predetermined position of the shaft, and regions intermediate each pair of adjacent areas, said code disc having a photosensitive material disposed on a surface thereof and a plurality of pairs of conductors disposed on said photosensitive material to define a plurality of sense elements including a separate sense element corresponding to each of said discrete areas, a first conductor of each pair including a plurality of concentric arcuate segments interconnected to form a continuous conductive path extending over a portion of the corresponding discrete area from the periphery of the code disc toward the center of the code disc and having projections which extend into the intermediate regions adjacent the corresponding discrete area and a second conductor having a plurality of concentric arcuate segments interconnected to form a continuous conductive path extending over the discrete area and the intermediate regions adjacent the discrete area in a spaced relationship with the first conductor forming a gap therebetween thereby exposing a continuous narrow strip of photosensitive material in the gap, each sense element providing a first resistance when energized and a second resistance when unenergized, source means including a phosphor radioactively energized to emit light mounted for rotation by said shaft relative to said sense elements for selectively energizing the sense element portions which are disposed adjacent thereto, the segments of conductors of adjacent sense elements which extend into a common intermediate region overlappinG one another to permit a pair of adjacent sense elements to be energized whenever said source means overlies a region intermediate a pair of adjacent sense elements.