THE ACCORDION CHARGE-TRANSFER MECHANISM - A NEW DEVELOPMENT OF THE FRAME-TRANSFER CCD IMAGE SENSOR

In frame-transfer (FT) sensors, the imaging area basically utilizes all incoming light. In state-of-the-art charge-coupled-device (CCD) sensors, this light is partly reflected and absorbed by the CCD gate electrodes. The basic FT sensor principle, however, does not preclude 100% light usage. The accordion mechanism, which reduces the absorbing gate electrode area, is a step toward this 100% goal. This improvement can be used to increase sensitivity or to enlarge the pixel number or a combination of these. The accordion versus the classic FT principle is explained, with emphasis on how this mechanism can benefit sensor characteristics. Finally, the design of the second-generation NXA 1100 (FT5) sensor, well suited to studio camera applications, is discussed.