Light sensing element having two functions

A light sensing element having two functions suitable applied to an image scanning device for scanning a document, the light sensing element comprising:

• a set of matrix light-sensing cells, having a plurality of light-sensing cells arranged in a matrix for detecting a scanning location for the scanned document and outputting detected data corresponding to the scanning location;
• at least one set of trilinear light-sensing cells, each of which has a plurality of light-sensing cells arranged in a linear array, for detecting a sensing region for the scanned scanning, and outputting image data corresponding to the sensing region;
• a sensed signal processing unit, coupled to the set of matrix light-sensing cells for processing the detected data from the set of matrix light-sensing cells and outputting corresponding sensed signals;
• at least one color signal processing unit, coupled to the associated set of trilinear light-sensing cells for processing the image data from the coupled set of trilinear light-sensing cells, and outputting image signals corresponding to the image data, wherein the image signals include red, green, and blue color signals;
• a plurality of buffers, respectively installed with the sensed signal processing unit and the color signal processing unit, for storing respectively the sensed signals and the image signals;
• and
• a synchronization processing unit, connected to the buffers for receiving the sensed signals and the image signals from the buffers and for synchronizing the sensed and the image signals to output;
• wherein the image scanning device adjusts the scanning location based on the sensed signals to acquire the image data.