Image sensor, semiconductor device and image sensing method

Abstract

An image sensor and an image sensing method can obtain image signals with a high S/N ratio in a high-speed image pickup operation. Signal charges are input to input transfer stageof CCD memory. Final transfer stageis formed so as to be connected to the input transfer stageand able to transfer signal charges to the input transfer stage. In an accumulation mode, read gateand drain gateare not turned on and the next transfer operation of the CCD memoryis conducted. The accumulated signal charges are transferred on a stage by stage basis and the signal charges obtained at the first image pickup timing are transferred again straightly to the input transfer stage. In this state, the signal charges obtained newly at photoelectric conversion sectionat the next image pickup timing are injected into the input transfer stageby way of input gate. As a result of this operation, the signal charges obtained at the last image pickup timing are added to the signal charges accumulated in the input transfer stageso that integrated signal charges obtained by adding the two sets of signal charges are accumulated in the input transfer stage