Digital light-to-frequency converter with preset voltage
First Claim
Patent Images
1. A radiant energy detecting and integrating circuit comprising:
- detecting means responsive to incident radiance for providing an output signal having an electrical characteristic which varies as a function of the intensity of incident radiation thereon;
means for integrating said output signal from said detecting means and providing an output signal which progressively increases in correspondence with the integrated value of said output signal from said detecting means; and
selectively actuatable preset means for providing an input signal to said integrating means prior to the incidence of radiation to said detecting means in order to enable said integrating means to provide a progressively increasing output signal, said preset means thereafter responding to said progressively increasing output signal from said integrating means reaching a select value for changing its said input signal to said integrating means so as to maintain said output signal from said integrating means at substantially said select value until radiation is incident to said detecting means.
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Abstract
A digital scene light detecting and integrating circuit is provided with an automatic preset by which the integrating circuit is presignaled to ramp upward to a preselected reference voltage value at which digital pulse counting can immediately begin, thereby subsequently enabling the precise detection and integration of illumination.
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Citations
22 Claims
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1. A radiant energy detecting and integrating circuit comprising:
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detecting means responsive to incident radiance for providing an output signal having an electrical characteristic which varies as a function of the intensity of incident radiation thereon; means for integrating said output signal from said detecting means and providing an output signal which progressively increases in correspondence with the integrated value of said output signal from said detecting means; and selectively actuatable preset means for providing an input signal to said integrating means prior to the incidence of radiation to said detecting means in order to enable said integrating means to provide a progressively increasing output signal, said preset means thereafter responding to said progressively increasing output signal from said integrating means reaching a select value for changing its said input signal to said integrating means so as to maintain said output signal from said integrating means at substantially said select value until radiation is incident to said detecting means. - View Dependent Claims (2, 3, 4, 5)
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6. A digital light detection and integration circuit comprising:
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detecting means responsive to incident illumination for providing an output signal having an electrical characteristic which varies as a function of the intensity of incident illumination; means for integrating said output signal from said detecting means and providing an output signal which progressively increases in correspondence with the integrated value of said output signal from said detecting means, said integrating means including an integration capacitor for receiving charging current during said integration; comparator means for comparing the level of said output signal from said integrating means with one select reference signal level and switching from a first select output signal level to a second select output signal level when the output signal level from said integrating means reaches said select reference signal level; means for discharging said integration capacitor in response to said comparator means switching to its said second select signal level until the level of said output signal from said integration means discharges to a selected value below said select reference signal thereby switching said comparator means output signal level back to its said first select level to disable said discharge means from further discharging said integration capacitor and resuming integration by recharging said integration capacitor; means for counting the number of times said comparator switches from its said first select output signal level to its said second select output signal level; and selectively actuatable preset means for providing an input signal to said integrating means prior to the incidence of light to said detecting means in order to enable said integrating means to provide a progressively increasing output signal, said preset means thereafter responding to said progressively increasing output signal from said integrating means reaching said selected value below said select reference signal for changing its said input signal to said integrating means so as to maintain said output signal from said integrating means at substantially said selected value below said select reference signal. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A photographic camera apparatus of the type adapted to be energized at least in part by a source of electrical energy and including means for defining a film plane comprising:
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a photoresponsive element stationed to receive light from the scene to be photographed to provide an output signal having an electrical characteristic which varies as a function of the intensity of scene light incident thereon; means for integrating said output signal from said photoresponsive element and providing an output signal which progressively increases in correspondence with the integrated value of said output signal from said photoresponsive element so as to ultimately control at least one exposure influencing event; selectively actuatable shutter means for controlling the admission of scene light to the film plane to define an exposure interval and for controlling the admission of scene light to said photoresponsive element to generally correspond with said exposure interval; and preset means responsive to the actuation of said shutter means for providing an input signal to said integrating means prior to the commencement of said exposure interval and the admission of scene light to said photoresponsive element in order to enable said integrating means to provide a progressively increasing output signal, said preset means thereafter responding to said progressively increasing output signal from said integrating means reaching a select value for changing its said output signal to said integrating means so as to maintain said output signal from said integrating means at substantially said select value until the commencement of said exposure interval. - View Dependent Claims (13, 14, 15, 16)
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17. A photographic camera apparatus of the type adapted to be energized at least in part by a source of electrical energy and including means for defining a film plane comprising:
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a photoresponsive element stationed to receive light from the scene to be photographed to provide an output signal having an electrical characteristic which varies as a function of the intensity of scene light incident thereon; means for integrating said output signal from said photoresponsive element and providing an output signal which progressively increases in correspondence with the integrated value of said output signal from said photoresponsive element, said integrating means including an integration capacitor for receiving charging current during said integration; comparator means for comparing the level of said output signal from said integrating means with one select reference signal level and switching from a first select output signal level to a second select output signal level when the output signal level from said integrating means reaches said select reference signal level; means for discharging said integration capacitor in response to said comparator means switching to its said second select signal level until the level of said output signal from said integration means discharges to a selected value below said select reference signal thereby switching said comparator means output signal level back to its said first select level to disable said discharge means from further discharging said integration capacitor and resuming integration by recharging said integration capacitor; means for counting the number of times said comparator switches from its said first select output signal to its said second select output signal level so as to ultimately control at least one exposure influencing event as a function of said count; selectively actuatable shutter means for controlling the admission of scene light to the film plane to define an exposure interval and for controlling the admission of scene light to said photoresponsive element to generally correspond with said exposure interval; and preset means responsive to the actuation of said shutter means for providing an input signal to said integrating means prior to the commencement of said exposure interval and the admission of scene light to said photoresponsive element in order to enable said integrating means to provide a progressively increasing output signal, said preset means thereafter responding to said progressively increasing output signal from said integrating means reaching said selected value below said select reference signal for changing its said input signal to said integrating means so as to maintain said output signal from said integrating means at substantially said selected value below said select reference signal. - View Dependent Claims (18, 19, 20, 21, 22)
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Specification