Touch device and waking up method thereof

A touch device, comprising:

• a sensing area configured to sense a finger of a user, wherein the sensing area comprises a plurality of sub sensing areas, and each of the sub sensing areas comprises a plurality of sensing points;
• and
• a sensing circuit electrically connected to the sensing area, wherein the sensing circuit is configured to perform steps of a waking up method of the touch device comprising:
• performing a sensing operation at a first time point to obtain a total capacitance value of the sensing area at the first time point, wherein the sensing operation comprises:
• sequentially performing a scan operation on each of the sub sensing areas to obtain a capacitance value of each of the sub sensing areas, wherein the scan operation comprises scanning a portion of the sensing points of the sub sensing area to obtain the capacitance value of the sub sensing area, and a number of the portion of the sensing points is smaller than a number of the sensing points;
• and
• summing up the capacitance value of each of the sub sensing area to obtain the total capacitance value;
• performing the sensing operation at a second time point to obtain a total capacitance value of the sensing area at the second time point;
• calculating a capacitance difference value between the total capacitance value at the first time point and the total capacitance value at the second time point;
• determining if an absolute value of the capacitance difference value is greater than a threshold capacitance value;
• and
• waking up the touch device when the capacitance difference value is greater than a threshold capacitance value.

A waking up method of a touch device, wherein the touch device comprises a sensing area comprising a plurality of sub sensing areas, and each of the sub sensing areas comprises a plurality of sensing points, and the waking up method comprises:

• performing a sensing operation at a first time point to obtain a total capacitance value of the sensing area at the first time point, wherein the sensing operation comprises:
• sequentially performing a scan operation on each of the sub sensing areas to obtain a capacitance value of each of the sub sensing areas, wherein the scan operation comprises scanning a portion of the sensing points of the sub sensing area to obtain the capacitance value of the sub sensing area, and a number of the portion of the sensing points is smaller than a number of the sensing points;
• and
• summing up the capacitance value of each of the sub sensing area to obtain the total capacitance value;
• performing the sensing operation at a second time point to obtain a total capacitance value of the sensing area at the second time point;
• calculating a capacitance difference value between the total capacitance value at the first time point and the total capacitance value at the second time point;
• determining if an absolute value of the capacitance difference value is greater than a threshold capacitance value;
• performing a fingerprint recognition step when the absolute value of the capacitance difference value is greater than the threshold capacitance value, wherein the fingerprint recognition step is configure to determine if a fingerprint sensed by the sensing area is substantially the same as a standard fingerprint;
• and
• waking up the touch device when the fingerprint sensed by the sensing area is substantially the same as the standard fingerprint.