Electronic camera having an illuminator with dispersing ring lens

An electronic camera for producing a digital image whose contrast is nearly constant over a field of view, comprising:

• a camera circuit including an image sensor and an adjustable shutter speed control, said camera circuit being configured to output an analog image signal;
• an optical assembly defining an optical axis and configured to define a field of view and a depth of field for image capture by said image sensor;
• an illuminator configured to approximately evenly illuminate the area within the field of view;
• a video gain circuit configured to receive said analog image signal and to output an amplified analog image signal;
• an analog-to-digital converter including an A/D gain controller responsive to an A/D reference input and configured to convert said amplified analog image signal from said image sensor to a digital image signal;
• a lens attenuation evaluator circuit configured to output to said A/D reference input a correction signal varying as a function of angle from said optical axis;
• and
• an intensity evaluator circuit configured to receive said digital image signal for each image capture and to provide a plurality of intensity-dependent control signals;
• said intensity evaluator circuit being connected to transmit a corresponding one of said control signals to said shutter speed control, said video gain circuit, and said lens attenuation evaluator circuit,
• such that overall gain control in said camera is obtained by controlling in combination shutter speed, video gain, and analog-to-digital converter gain, responsive to evaluation of image brightness.

An electronic camera for producing a digital image, comprising:

• a camera circuit including an image sensor, said camera circuit being configured to output an analog image signal;
• a optical assembly including a lens and defining an optical axis and configured to define a field of view and a depth of field for image capture by said image sensor;
• a lens attenuation evaluator circuit configured to apply a correction signal, said correction signal being selected from a plurality of stored signals each providing a different average gain adjustment and varying as a function of angle from said optical axis;
• an analog-to-digital converter configure to convert said analog image signal from said image sensor to a digital image signal, said analog-to-digital converter including an A/D gain controller responsive to an A/D reference input, wherein said lens attenuation evaluator circuit is configured to apply said correction signal to said A/D reference input;
• and
• an intensity evaluator circuit configured to receive said digital image signal and to provide an intensity-dependent control signal to said lens attenuation evaluator circuit.

An electronic camera for producing a digital image, comprising:

• a camera circuit including an image sensor, said camera circuit being configured to output an analog image signal;
• an optical assembly including a lens and defining an optical axis and configured to define a field of view and a depth of field for image capture by said image sensor;
• an illuminator configured to illuminate the field of view;
• an analog-to-digital converter including an A/D gain controller responsive to an A/D reference input and configured to convert said analog image signal from said image sensor to a digital image signal;
• a lens attenuation evaluator circuit configured to output to said A/D reference input a correction signal varying as a function of angle from said optical axis;
• and
• an intensity evaluator circuit configured to receive said digital image signal and to provide a plurality intensity-dependent control signals;
• said intensity evaluator circuit being connected to transmit one of said plurality of control signals to said lens attenuation evaluator circuit.