Fingerprint image generation method and device for saving memory

A method of fingerprint image generation for saving memory comprising:

• determining a touch position of a finger touch event occurring on a touch display screen, wherein the touch display screen comprises a touch sensor array comprising a plurality of touch sensing electrodes and a fingerprint sensor array comprising a plurality of fingerprint sensing pixels;
• finding out positions of touch sensing electrodes which are corresponding to a plurality of touch sensing data larger or not less than a threshold;
• generating a first fingerprint image corresponding to a fingerprint readout area which is determined based on the touch position;
• and
• storing a part of the first fingerprint image, taken as a valid fingerprint image, wherein an area of the valid fingerprint image is determined according to the positions of the touch sensing electrodes which are corresponding to the touch sensing data larger or not less than the threshold.

A device for fingerprint image generation for saving memory comprising:

• an analog to digital converter for generating a first fingerprint image of an original data size according to a plurality of first analog sensing signals which are read from a fingerprint sensor array before an exposure period ends;
• a memory for storing the first fingerprint image represented by a first data size which is equivalent to or smaller than the original data size;
• the analog to digital converter generating a second fingerprint image of the original data size after generating the first fingerprint image of the original data size according to a plurality of second analog sensing signals which are read from the fingerprint sensor array during the exposure period;
• and
• the memory storing the second fingerprint image represented by a compressed data size smaller than the original data size.

A device for fingerprint image generation for saving memory comprising:

• a touch controller for determining a touch position of a finger touch event occurring on a touch display screen, wherein the touch display screen comprises a touch sensor array comprising a plurality of touch sensing electrodes and a fingerprint sensor array comprising a plurality of fingerprint sensing pixels;
• the touch controller finding out positions of touch sensing electrodes which are corresponding to a plurality of touch sensing data larger or not less than a threshold;
• a fingerprint readout circuit for generating a first fingerprint image corresponding to a fingerprint readout area which is determined based on the touch position;
• and
• the fingerprint readout circuit storing a part of the first fingerprint image, taken as a valid fingerprint image, wherein an area of the valid fingerprint image is determined according to the positions of the touch sensing electrodes which are corresponding to the touch sensing data larger or not less than the threshold.