Linear array signal processing circuitry for locating the midpoint of a source of light

Claim 2

Processing circuitry for locating the geometric mid-point of an illuminated stretch of a linear photodetector array, where the array is scanned in a scanning cycle to provide, from such illumination, a signal taking the form of plural, time-adjacent, discreet DC voltage levels, said circuitry, in operative condition with respect to such an array, comprising means operatively connected to said array for filtering such a signal to produce a related DC analogue pulse lacking discreet voltage levels, means operatively connected to said filtering means for producing a square-wave pulse having a duration directly related to the time that the level of such an analogue pulse exceeds a predetermined voltage level, and means operatively connected to said square-wave pulse-producing means for determining the time mid-point thereof.

Claim 3

The circuitry of claim 1, wherein said determining means includes a clock-pulse generating means, and a counter operatively connected thereto for counting clock pulses generated thereby during a portion of such a scanning cycle.

Claim 4

The circuitry of claim 2, wherein said counter is constructed whereby said portion of a scanning cycle begins at the beginning of the cycle and ends at the termination of such a square-wave pulse.

Claim 5

The circuitry of claim 3, wherein said counter includes a pair of counting inputs, said clock-pulse generating means includes a pair of outputs each operatively connected to a different one of said inputs, one of said outputs supplying clock pulses at one frequency for counting from the beginning of a scan cycle to the beginning of a square-wave pulse, and the other output supplying clock pulses at another frequency, which is one-half said one frequency, for counting throughout the duration of such a square-wave pulse.

Claim 6

Processing circuitry for locating the geometric mid-point of a signal derived from a time-base-scanned linear photodetector array, where scanning of the array occurs in recurrent scanning cycles, and such a signal takes the form of plural, time-adjacent, discreet DC voltage levels, said circuitry, in operative condition with respect to such an array, comprising filter means operatively coupled to said array, operable to produce from such a signal a related analogue DC pulse lacking discreet voltage levels, means for producing a DC reference voltage, comparator means operatively connected both to said filter means and to said reference voltage producing means, operable to compare such a pulse with said reference voltage, and to provide from such comparing a square-wave pulse having a duration directly related to the length of time that the level of such an analogue pulse exceeds that of said reference voltage, first clock-pulse means producing clock pulses at one frequency, second clock-pulse means producing clock pulses at another frequency which is one-half said one frequency, and counter means operatively connected to said comparator means and to said first and second clock-pulse means, operable, during each scanning cycle, to count pulses received from said first clock-pulse means from the beginning of the cycle to the beginning of a square-wave pulse produced by said comparator means, and thereafter to count pulses received from said second clock-pulse means throughout the duration of such a square-wave pulse.

Claim 7

Processing circuitry for locating the geometric mid-point of a signal derived from a time-base-scanned linear photodetector array, where scanning of the array occurs in recurrent scanning cycles, and such a signal takes the form of plural, time-adjacent, discreet DC voltage levels, said circuitry, in operative condition with respect to such an array, comprising filter means operatively coupled to said array, operable to produce from such a signal a related analogue DC pulse lacking discreet voltage levels, means for producing a DC reference voltage, comparator means operatively connected both to said filter means and to said reference voltage producing means, operable to compare such a pulse with said reference voltage, and to provide from such comparing a square-wave pulse having a duration directly related to the length of time that the level of such an analogue pulse exceeds that of said reference voltage, first clock-pulse means producing clock pulses at one frequency, second clock-pulse means producing clock pulses at another frequency which is one-half said one frequency, and counter means operatively connected to said comparator means and to said first and second clock-pulse means, operable, during each scanning cycle, to count pulses received from said first clock-pulse means from the beginning of the cycle to the beginning of a square-wave pulse produced by said comparator means, and thereafter to count pulses received from said second clock-pulse means throughout the duration of such a square-wave pulse.