Imaging apparatus with electrical exposure time control
AssigneeOlympus Optical Co., Ltd.
InventorTakayuki Kijima
Life of this patent
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Abstract
An imaging apparatus with electrical exposure time control function capable of high accuracy control of the electronic shutter and ensuring high exposure accuracy is disclosed. An imaging element accumulates signal charge corresponding to an incident scene light flux in a photo-electric converting element section. The accumulated signal charge is read out as a pixel signal. Charge accumulation control means controls the instant of ending of charge accumulation in the imaging element to an instant other than the horizontal blanking period and/or controls the instant of ending of charge accumulation in the imaging element in time units shorter than the horizontal sync signal interval.
Claims16
A method for controlling an exposure time by controlling a charge accumulation time of a photodiode of an imaging element in synchronism with a transfer gate pulse signal, the method comprising:
- a) obtaining a reference horizontal clock number by
- i) determining a product of a unit clock number and a determined integral number, wherein the unit clock number is the number of reference horizontal clocks in one horizontal line scanning time divided by a first predetermined integral number, and wherein the determined integral number is determined based on a required effective exposure time to be regulated, and
- ii) adding the determined product to a second predetermined integral number to generate the reference horizontal clock number, wherein the second predetermined integral number is larger than a number of reference horizontal clocks in a horizontal blanking time;
- and
- b) generating the transfer gate pulse signal at an instant after the lapse of a required effective exposure time defined by the reference horizontal clock number times the time for a reference horizontal clock, from a predetermined reference instant.
For use with a camera having an imaging device and a signal generator for generating horizontal synchronization signals and vertical synchronization signals for reading out information captured by the imaging device, an apparatus for controlling an exposure time by controlling a charge accumulation time of a photodiode of the imaging element in synchronism with a transfer gate pulse signal, the apparatus comprising:
- a) a central processing unit adapted to generate an integral number based on a required effective exposure time to be regulated;
- and
- b) a timing generator, the timing generator
- i) being coupled with the central processing unit for receiving the integral number,
- ii) being coupled with the imaging device for providing the transfer gate pulse signal to the imaging device, and
- iii) adapted to generate the transfer gate pulse signal by
- A) obtaining a reference horizontal clock number by
- 1) determining a product of a unit clock number and the integral number generated by and provided from the central processing unit, wherein the unit clock number is the number of reference horizontal clocks in one horizontal line scanning time divided by a first predetermined integral number, and
- 2) adding the determined product to a second predetermined integral number to generate the reference horizontal clock number, wherein the second predetermined integral number is larger than a number of reference horizontal clocks in a horizontal blanking time, and
- B) generating the transfer gate pulse signal at an instant after the lapse of a required effective exposure time defined by the reference horizontal clock number times the time for a reference horizontal clock, from a horizontal synchronization signal provided by the signal generator.
Dependencies are inferred from the claim text.