Light measuring and indicating circuit
AssigneeNippon Kogaku K.K.
InventorKenji Toyoda
Life of this patent
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Abstract
A light measuring and indicating circuit utilizing indicating elements such as light-emitting diodes, to indicate corresponding light intensity levels. Intermediate levels are indicated without increasing the number of flip-flops employed in an activating circuit for the light-emitting diodes by intentionally causing the circuit to activate light-emitting diodes alternately. The activating circuit includes a reversible digital counter controlling the light-emitting diodes, two comparators for operating the counter reversibly in response to the comparison of light-dependent and standard signals, and a digital-to-analog converter which varies one or more of said signals in accordance with a counter output.
Claims21
A light measuring and indicating circuit comprising means for producing three signals, the value of one of which varies relative to the values of the others in accordance with light intensity, comparator means for producing a first output when said one signal has a value less than the values of the other signals and for producing a second output when said one signal has a value greater than the values of said other signals, reversible counter means, means for operating said counter means in one direction in response to said first output, means for operating said counter means in the opposite direction in response to said second output, indicator means responsive to an output from said counter means, and means for controlling the value of said one signal relative to the values of the other signals in response to an output from said counter means.
A light measuring and indicating circuit including indicator means having a plurality of indicator elements, and comprising means for activating different indicator elements in response to corresponding predetermined light intensity levels and for activating indicator elements alternately when the light intensity is intermediate the levels corresponding to those indicator elements, said activating means comprising a reversible digital counter having successive stages for controlling the activation of said indicator elements.
Dependencies are inferred from the claim text.