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US 4,396,951 AGranted
Solid-state imaging apparatus provided with automatic iris control means
AssigneeNippon Electric Co., Ltd.
InventorTakanori Tanaka
Life of this patent
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AssigneeNippon Electric Co., Ltd.
InventorTakanori Tanaka
Estimating the term…
A solid-state imaging apparatus has an optical iris and a CCD imaging device which responds to light received from an object for producing a picture signal component and a reference black level signal component. A limiter limits the amplitude of the black level component to less than a predetermined value and the amplitude of the reference black level signal component is higher when the CCD imaging device is receiving such a quantity of light that the electric charges generated by photo-charge conversion in the light-sensitive elements in the CCD imaging device may not overflow from the light-sensitive elements. The limited amplitude is lower than the amplitude of the reference black signal component when the electric charges generated by photo-charge conversion in the light-sensitive elements overflow from the light-sensitive elements. A clamp circuit clamps the output from the CCD imaging device derived after passing through the limiter so that the reference black level signal component may take a predetermined voltage. An iris control circuit responds to the output of the clamp circuit for controlling the optical iris when the electric charges generated by photocharge conversion in the light-sensitive elements in the CCD imaging device have overflown from the light-sensitive elements. The signal level of the reference black level signal component output from the limiter may be restored to the signal level of the reference black level signal component when the electric charges generated by photocharge conversion in the light-sensitive elements in the CCD imaging device do not overflow. The same conditions arises in the reproduced picture, at the moment when an excessively large quantity of light would be received by human eyes. Hence, a viewer of the reproduced picture does not have an unnatural feeling.
A solid-state imaging apparatus comprising:
A method for providing automatic iris control in a solid-state imaging apparatus using a charge transfer image device having a plurality of light sensitive elements, said charge transfer imaging device producing an output signal including a first signal responsive to an optical signal and a second signal which is used for producing a reference level of a video signal, and an optical iris responsive to said output signal from said charge transfer imaging device for controlling a quantity of light incident to said charge transfer imaging device, said method comprising the steps of:
A control circuit for regulating the amount of light in an image on a solid state imaging device, said control circuit comprising a plurality of light sensitive means, each of said light sensitive means storing and releasing photocharges which are proportional to the amount of light in said image thereon, means responsive to said photocharges for producing a video signal and a reference signal, each of said light sensitive means having a limited charge storage capacity, said reference signal being related to the charge storage capacity of said light sensitive means, means responsive to the amplitude of said reference signal exceeding the amplitude of a black level signal for limiting said reference signal to a predetermined level which is lower than the amplitude of said video signal, and means for reducing the amount of light in said image on said imaging device responsive to the level of said video signal exceeding said limited reference signal.
Dependencies are inferred from the claim text.