Digital Imaging Systems Gmbh

Mark Nussbächer

Giuseppe D'onofrio

An improved method for photon transfer curve (PTC) testing in an image sensor is described. A cost and time savings is achieved by reducing the number of frames necessary for measurements to two that are generated by illuminating a first plurality of pixel rows at a first intensity level m, a second plurality of pixel rows at a second intensity level t, and so forth up to an nth plurality of pixel rows illuminated at an nth intensity level mwhere m&#x3e;m&#x3e;m. The resulting image has 'n' regions each with a different brightness. The highest intensity level essentially saturates the pixels in the nth region. In one example, a four row exposure and five intensity levels are employed in the illuminator sequence. An intelligent light source is pre-programmable with illumination intensity settings and is synchronized to the image sensor using HSYNC and VSYNC signals, for example.

Photon transfer curve test time reduction

An improved on chip test method for determining the photon transfer curve (PTC) and dark current in an image sensor is described. Cost and time savings is achieved by reducing the number of frames necessary for the measurements to three including two exposure frames and one frame for dark current testing. A conventional test involving 'n' different exposure times each with two frames is replaced by implementing a snap shot mode where a first plurality of pixel rows are exposed for a time t, a second plurality of pixel rows are exposed for a time t, and so forth up to an nth plurality of pixel rows exposed for a time twhere the total number of pixel rows equals a frame and t&#x3e;t&#x3e;t. The resulting image has 'n' regions each with a different brightness that become progressively brighter from top to bottom of the image.

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Kirchheim Teck, Germany

Mark Nussbächer