Contactless input device

A contactless input device comprising:

• an operating surface, over which an input operation is performed by a hand in a contactless manner;
• a plurality of sensor electrodes arranged along the operating surface, the plurality of electrodes being configured to individually detect respective capacitances according to proximity of the hand to the operating surface;
• and
• a determination unit configured to calculate a sharpness indicating a part of the hand for a plurality of locations on the operating surface based on the respective capacitances detected by the plurality of sensor electrodes, and to determine an input location of the input operation based on the sharpness obtained at the plurality of locations,
• wherein the plurality of sensor electrodes are arranged in a matrix having rows and columns,
• and wherein the determination unit is configured to:
• calculate the sharpnesses, row by row, for a plurality of rows of the sensor electrodes, by curve fitting the capacitances of successive 2n+1 sensor electrodes in each row of the sensor electrodes, the 2n+1 sensor electrodes including a particular sensor electrode which yields a maximum capacitance among the capacitances obtained from the row of the sensor electrodes,
• when the particular sensor electrode which yields the maximum capacitance in the row of the sensor electrodes is located n or more sensor electrodes away from an edge of the row, select the 2n+1 sensor electrodes such that the 2n+1 sensor electrodes includes the particular sensor electrode which yields the maximum capacitance and n sensor electrodes on each side of the particular sensor electrode in the row;
• and
• when the particular sensor electrode which yields the maximum capacitance is located less than n sensor electrodes away from the edge of the row, select the 2n+1 sensor electrodes from the edge of the row so as to include the particular sensor electrode which yields the maximum capacitance.

A contactless input device comprising:

• an operating surface, over which an input operation is performed by a hand in a contactless manner;
• a plurality of sensor electrodes arranged along the operating surface, the plurality of electrodes being configured to individually detect respective capacitances according to proximity of the hand to the operating surface;
• and
• a determination unit configured to calculate a sharpness indicating a part of the hand for a plurality of locations on the operating surface based on the respective capacitances detected by the plurality of sensor electrodes, and to determine an input location of the input operation based on the sharpness obtained at the plurality of locations, the sharpness being calculated by curve fitting the capacitances of the sensor electrodes or curve fitting reciprocals of the capacitances of adjacent sensor electrodes, a curvature of the curve fitting indicating a shape of the part of the hand,
• wherein the determination unit is further configured to:
• perform a linear approximation of sensor electrode locations of a predetermined number of sensor electrodes, among the plurality of sensor electrodes, which yield capacitances greater than that of other sensor electrodes, to obtain an approximation line using a least-squares method;
• identify a direction of the approximation line as a finger direction;
• and
• set a calculation direction along which the sharpness is calculated such that an intersecting angle of the calculation direction and the finger direction increases.