CMOS active pixel sensor with a chess-pattern pixel layout
Pixels in an area image sensor are normally arranged in a regular matrix, because this is the best way for sensor layout, display and image processing. Image sensors in CMOS aps technologies offer great flexibility in the design. Nearly any shape for the light-sensitive fotodiode and any arrangements are possible. But one disadvantage of CMOS aps (active pixel sensor) is, that they need some space in the sensitive area for the electronic pixel circuitry. We developed and investigated a CMOS sensor with a chessboard like pixel pattern, where the white fields are the sensitive fotodiodes and the black fields are for electronic circuitry. The black fields must be interpolated for displaying. So we get an image with a double number of pixels, which is again a regular matrix of pixels which can be displayed on a monitor and is suited for standard image processing. We compared such a chess-pattern sensor with regular matrix image sensors. For this we made some computer simula tions of these variations regarding the number of pixels and the optical fill factor. The performance of the images is evaluated concerning technical data, like line-resolution, SFR, artefacts and the visual impression as well. We show simulations with real images of the same scene: Two simulations are with a normal regular pixel arrangement and the other with a sensor having a chesspattern pixel arrangement. Sensor with chess-pattern pixel arrangement can be used in video-, industrial- and still picture-cameras for black and white and color imaging. It will result in an improved image quality compared to regular matrix sensors.