Optical encoder with pnpn diode sensing

Claim 2

An analog to digital encoder comprising, in combination: a code member adapted to move responsive to the analog information to be encoded, said code member having a track consisting of a plurality of transparent sectors and opaque sectors, each transparent sector being separated from adjacent transparent sectors by an opaque sector, a light source mounted in a fixed position relative to the code member and confronting a portion of the code member to illuminate said portion of the code member, and a photoresponsive device mounted on the side of the code member opposite the light source aligned with the track of the code member and the light source, characterized by the improved construction wherein the photoresponsive device comprises a PNPN switching diode disposed in alignment with the track and light source and an electrical pulse generator electrically connected in series with the switching diode, said switching diode being photoresponsive and having a breakover voltage inversely related to the intensity of illumination falling on said switching diode, a voltage divider connected between the pulse generator and the switching diode, said voltage divider comprising a first resistor and a second resistor connected in series across the pulse generator and the switching Diode being in a circuit electrically connected in parallel with the second resistor, said pulse generator impressing a voltage on said switching diode greater than the breakover voltage of the switching diode when illuminated by the light source and less than the breakover voltage of the switching diode when in the dark, and an output terminal operatively associated with said switching diode circuit.

Claim 3

An analog to digital encoder comprising, in combination: a code member adapted to move responsive to the analog information to be encoded, said code member having a plurality of parallel tracks, each track having a plurality of transparent sectors separated by opaque sectors, the length of the sectors of the track being different and dividing the track into a plurality of segments along the tracks of unique combinations of transparent sectors and opaque sectors, a light source mounted in a fixed position relative to the code member and confronting a portion of the code member to illuminate said portion of the code member, and a plurality of photoresponsive devices mounted on the side of the code member opposite the light source, a separate photoresponsive device being aligned with each track of the code member and the light source, characterized by the improved construction where each of the photoresponsive devices comprises a PNPN switching diode and an electrical pulse generator electrically connected in a separate series circuit with each of the photoresponsive switching diodes, each of said separate series circuits including a voltage divider comprising a first resistor and a second resistor connected in series across the pulse generator, the switching diode being in a circuit, including a third resistor, electrically connected in parallel with the second resistor, each switching diode being photoresponsive and having a breakover voltage inversely related to the intensity of illumination falling on the said switching diode, said pulse generator impressing a voltage on each of said switching diodes greater than the breakover voltage of said switching diode when illuminated by the light source and less than the breakover voltage of each said switching diode when said switching diode is in the dark, and output means operatively associated with each switching diode circuit.

Claim 4

An analog to digital encoder comprising, in combination: a code member adapted to move responsive to the analog information to be encoded, said code member having a plurality of parallel tracks, each track having a plurality of transparent sectors separated by opaque sectors, the length of the sectors of the track being different and dividing the track into a plurality of segments along the tracks of unique combinations of transparent sectors and opaque sectors, a light source mounted in a fixed position relative to the code member and confronting a portion of the code member to illuminate said portion of the code member, and a plurality of photoresponsive devices mounted on the side of the code member opposite the light source, a separate photoresponsive device being aligned with each track of the code member and the light source, characterized by the improved construction where each of the photoresponsive devices comprises a PNPN switching diode and an electrical pulse generator electrically connected in a separate series circuit with each of the photoresponsive switching diodes, each of said separate series circuits including a voltage divider comprising a first resistor and a second resistor connected in series across the pulse generator, the switching diode being in a circuit, including a third resistor, electrically connected in parallel with the second resistor, each switching diode being photoresponsive and having a breakover voltage inversely related to the intensity of illumination falling on the said switching diode, said pulse generator impressing a voltage on each of said switching diodes greater than the breakover voltage of said switching diode when illuminated by the light source and less than the breakover voltage of each said switching diode when said switching diode is in the dark, and output means operatively associated with each switching diode circuit.

Claim 5

An analog to digital encoder comprising the combination of claim 2 wherein the encoder is provided with separate output terminals for each track of the code member, each of said output terminals being electrically connected to a different one of said third resistors connected in a series circuit with one of the switching diodes and the pulse generator.

Claim 6

An analog to digital encoder comprising the combination of claim 2 wherein the pulse generator has a plurality of output terminals, a different one of said output terminals being electrically connected to the voltage divider of each photoresponsive switching diode, said pulse generator generating pulses on said different output terminals in sequence, and a common pair of output terminals electrically connected in a series circuit with all of the said third resistors connected in series circuits with the pulse generator and switching diodes.