초록 ▼

A method for controlling the exposure of an active pixel array electronic still camera includes the steps of: integrating photocurrent in each pixel during an integration time period; collecting overflow charge from all pixels in the array during the integration time period; developing an overflow s

A method for controlling the exposure of an active pixel array electronic still camera includes the steps of: integrating photocurrent in each pixel during an integration time period; collecting overflow charge from all pixels in the array during the integration time period; developing an overflow signal as a function of the overflow charge; and terminating the integration time period when the overflow signal exceeds a preset threshold level selected to represent a desired reference exposure level. Apparatus for performing the method of the present invention includes circuitry for integrating photocurrent in each pixel during a integration time period; circuitry for diverting and detecting overflow charge from all pixels in the array during the integration time period; circuitry for developing an overflow signal as a function of the overflow charge; and circuitry for terminating said integration time period when the overflow signal exceeds a preset threshold level selected to represent a desired reference exposure level.

대표청구항 ▼

1. A method for controlling the exposure of an active pixel array disposed on a semiconductor substrate, comprising the steps of:adjusting a charge barrier in each said pixel to a first overflow level;integrating photocurrent in each said pixel during a first integration time period while said charg

1. A method for controlling the exposure of an active pixel array disposed on a semiconductor substrate, comprising the steps of:adjusting a charge barrier in each said pixel to a first overflow level;integrating photocurrent in each said pixel during a first integration time period while said charge barrier is set at said first overflow level;collecting overflow charge from all said pixels in said array during said first integration time period;developing an overflow signal;adjusting said charge barrier for each said pixel to a second overflow level when said overflow signal exceeds a predetermined threshold;determining a duration for a second integration time period;integrating photocurrent in each said pixel during said second integration time period while said charge barrier is set at said second overflow level; andterminating said second integration time period after said determined duration. 2. A method for controlling the exposure of an active pixel array disposed on a semiconductor substrate, comprising the steps of:resetting each pixel during a reset time period;adjusting a charge barrier in each said pixel to a first overflow level;integrating photocurrent in each said pixel during a first integration time period while said charge barrier is set at said first overflow level;collecting overflow charge from all said pixels in said array during said first integration time period;developing an overflow signal;adjusting said charge barrier for each said pixel to a second overflow level when said overflow signal exceeds a predetermined threshold;determining a duration for a second integration time period;integrating photocurrent in each said pixel during said second integration time period while said charge barrier is set at said second overflow level; andterminating said second integration time period after said determined duration. 3. An apparatus for controlling the exposure of an active pixel array, comprising:means for adjusting a charge barrier in each pixel to a first overflow level;means for integrating photocurrent in each said pixel during a first integration time period while said charge barrier is set at said first overflow level;means for collecting overflow charge from all said pixels in said array during said first integration period;means for developing an overflow signal;means for adjusting said charge barrier for each said pixel to a second overflow level when said overflow signal exceeds a predetermined threshold;means for determining a duration for a second integration time period;means for integrating photocurrent in each said pixel during said second integration time period while said charge barrier is set at said second overflow level; andmeans for terminating said second integration time period after said determined duration.