Solid-state image sensor and image sensing method

The invention relates to a solid-state image sensor and an image sensing method. According to one embodiment, the solid-state image sensor can comprise a pixel array, an analog-digital converter and an output unit; the pixel array is provided with multiple pixel units, which are arranged in lines and columns; each pixel unit is provided with a photoelectric conversion device for converting opticalsignals into electric signals; the analog-digital converter is configured to convert analog electric signals generated by each pixel unit into digital signals, so that the pixel value of each pixel unit is obtained; and the output unit is configured to output a difference value between the pixel value of the current frame and the pixel value of a previous frame. The solid-state image sensor disclosed by the invention can only send a changed pixel difference value, namely a non-zero difference value; therefore, the data transmission bandwidth is saved; the frame rate can be increased; and furthermore, the subsequent i