The invention discloses an image sensor comprising a pixel array for outputting light intensity signals of the pixel array, an array processing circuit for serially outputting the light intensity signals of the pixel array, which are output by the pixel array, an analogue/digital converter for converting light intensity voltage signals output by the array processing circuit into digital light intensity signals, a digital processing circuit for processing the digital light intensity signals output by the analogue/digital converter and outputting image information, wherein the analogue/digital converter comprises a control circuit, and the control circuit is used for controlling the opening and the closing of at least one subunit in the analogue/digital converter. The image sensor reduces power consumption of the image sensor and reduces waste.