US 3,934,161 A · Electronic shutter for a charge-coupled imager

Abstract

The disclosure relates to a system for controlling the total charge collected on a charge-coupled imager to, in effect, provide an electronic shuttering action for the charge-coupled imager. The charge-coupled imager works in standard fashion and is normally biased into depletion whereby minority carriers, generated by the light impinging on the imager, are collected in predetermined charge collecting areas or wells, the charges in each well then bring read out in a serial fashion. In order to prevent collection of an excess number of charges, which is equivalent to overexposure in a photographic sense, the majority carriers which are necessarily generated simultaneously with the minority carriers, are collected and integrated so that when a predetermined amount of charge is measured, a shuttering action can take place. When the basic imager is formed from p-type silicon, the majority carrier charges are collected by providing an ohmic contact to the p-type substrate. Two modes ofoperation are disclosed. The first mode is suitable for imaging applications and the second mode is suitable for laser warning receivers.

Claims19

Dependent claims

An electronic shutter for a charge-coupled imager which comprises, in combination:

a. a charge-coupled imager comprising a substrate of semiconductor material of predetermined conductivity type, an insulating layer on a surface of said substrate, and plural transfer electrodes over said insulating layer such that radiation incident on said imager causes generation of minority carrier-majority carrier pairs in said substrate for storage of minority-carrier charge beneath said transfer electrodes during an integration period;
b. storage means coupled to said imager;
and
c. means electrically connected to said substrate for responding to current flow induced by said majority carriers to cause transfer to said storage means of said minority carrier induced charge stored beneath said transfer electrodes and for terminating said integration period, at a predetermined level of said current.

1 more element

An electronic shutter for a charge-coupled imager having a substrate of semiconductor material of predetermined conductivity type, an insulation layer on one surface thereof, and a plurality of spaced transfer electrodes disposed on said insulation layer, said electronic shutter comprising:

a. charge storage means coupled to said imager;
b. substrate bias circuit means having a bias line connected to said substrate and being responsive to current induced in said bias line by majority carriers generated in the operation of said imager;
and
c. control means operably connected to said substrate bias circuit means for controlling said substrate bias circuit means so as to impart bias to said substrate in a manner regulating charge transfer from said imager to said storage means, said control means comprising:
i. an integrator circuit connected to said bias line for receiving current therefrom,
ii. a threshold device connected to the output of said integrator circuit and being responsive to an output of a predetermined magnitude to generate a threshold signal, and
iii. a comparator connected to the output of said threshold device and being actuated upon receiving a threshold signal therefrom to provide an output signal, and
iv. said substrate bias circuit means being connected to said comparator and being responsive to an output signal therefrom for imparting bias to said substrate so as to transfer charge represented by minority carriers collected by said imager from said imager to said storage means.

5 more elements

Dependencies are inferred from the claim text.

Electronic shutter for a charge-coupled imager

Life of this patent

Electronic shutter for a charge-coupled imager

Life of this patent

Abstract

Claims19