Low power uniform high luminous intensity digital display

A light emitting digital display comprising

• a clock for providing a stable reference frequency output
• a segment scan circuit coupled to said reference frequency output having a segment scan frequency and producing a plurality of sequential segment control signals in each segment scan cycle, each segment control signal having a first dwell time,
• a digit scan circuit coupled to said references frequency output having a digit scan frequency above the frequency response of the eye and producing a plurality of sequential digit control signals in each digit scan cycle, each digit control signal having a second dwell time at least as long as the period of said segment scan frequency,
• a plurality of digit arrays,
• a plurality of segments in each of said digit arrays arranged in relative position to represent predetermined symbols when electric current is passed through selected segments causing said segments to emit light,
• a plurality of means for enabling said digit arrays having inputs coupled to ones of said plurality of sequential digit control signals and outputs connected to said plurality of segments, said last named means being adjusted to pass a predetermined level of electric current,
• a plurality of segment drivers having inputs coupled to ones of said plurality of sequential segment control signals and outputs connected to ones of said plurality of segments in each of said digit arrays,
• a pair of exposed electrodes,
• a switch responsive to placement of the resistance of a biological segment across said pair of electrodes for actuating said segment scan circuit, whereby said selected segments have a short duty cycle equivalent to said first dwell time during each digit scan cycle so that higher electric current levels may be passed through said segments for producing higher brightness levels there from while maintaining average current at or below levels for longer duty cycles.

A light emitting digital display circuit comprising

• a clock for providing a reference frequency,
• a segment scan circuit for providing a repeating segment scan cycle output when enabled,
• said scan cycle output being related to said reference frequency,
• said segment scan cycle having a plurality of sequential segment signals therein,
• a plurality of light emitting segments for receiving said segment signals within a segment scan cycle,
• a plurality of digit arrays formed by said segments for providing predetermined symbols according to selected segments being energized therein,
• a digit scan circuit for providing a repeating digit scan cycle output related to said reference frequency,
• said digit scan cycle having a plurality of sequential digit signals therein,
• said segment scan cycle having a period equivalent to the dwell time of one of said sequential digit signals,
• a switch for enabling said scan circuit,
• a plurality of segment drivers for receiving ones of said plurality of sequential segment signals and for passing current to a connected segment,
• a plurality of digit drivers for receiving ones of said plurality of sequential digit signals, thereby sequentially enabling ones of said plurality of digit arrays,
• whereby said segments are scanned in each digit array during the dwell time of each of said sequential digit signals, and segment duty cycle is reduced to the ratio of said sequential segment signal dwell time to said digit scan cycle period so that high peak current may be passed through selected segments to obtain a high brightness level while average current therethrough is minimized.

A method of presenting a light emitting digital display comprising the steps of

• scanning a number of digits,
• scanning a number of segments in each digit for each digit scan,
• presetting a current level for passing through each segment, whereby only one segment passes current at a time,
• whereby a high current level may be passed through each segment for a short time period to obtain high luminous intensity therefrom while using low average current,
• sensing the ambient light level, and controlling the preset current level to vary relative to the ambient light level,
• thereby providing an adjusted current level to obtain desired display contrast continuously as ambient light level changes.