MOS FET camera chip and methods of manufacture and operation thereof

DETAILED DESCRIPTION An object of this invention is to provide an integrated circuit which functions as an image detector which employs two transistors in a photosensor pixel array with reduced parasitics.
Another object of this invention is to provide a photosensor pixel array with an integrated power amplifier on the chip.
A further object of this invention is to provide a photosensor pixel array which provides an output signal which is a measure of the strength of focus of the image.
Still another object of this invention is a photosensor pixel array comprising a part of an autofocus system.
One way of determining the strength of focus is by comparing the contrast (i.
e.
, the difference in signal intensity) of the output from adjacent sense cells (or adjacent groups of sense cells).
The larger the difference in signal intensity, the stronger the focus.
The strength of focus may be used in a camera chip system to determine that position of an external lens which provides maximal focus of the incident light (and image) to the chip sense-array surface.
Hence, it may be used to allow the camera chip to autofocus, i.
e.
, automatically self-adjust to provide a maximally focussed image.
An example of a camera autofocus mechanism is shown in the configuration in FIG.
8 in which a light beam 62 is directed through a camera lens 63 as focussed beam 62' towards the surface of a sense-array chip 64.
FIG.
8 illustrates a feedback system in which an electromechanical device (e.
g.
, a miniature motor 67) is used to operate a conventional mechanical linkage 68 shown in phantom to adjust the distance between the camera lens 63 and the sense-array surface of the chip 64.
The motor control block 65 receives a signal F (Focus) on line 64' from the camera chip 64.
Control block 65 provides a signal on line 65' which controls the motor 67 energizes mechanical link 68 to adjust the distance along the direction of the dotted line arrows between the chip 64 and the lens 63, step-wise, in that direction which increases the value of F (Focus)