One type of touch sensor device operates by way of capacitance sensing utilizing capacitance sensors. The capacitance detected by a capacitance sensor changes as a function of the proximity of a conductive object to the sensor. The conductive object can be, for example, a stylus or a user's finger. In a touch sensor device, a change in capacitance detected by each sensor in the X and Y dimensions of the sensor array due to the proximity or movement of a conductive object can be measured by a variety of methods. Regardless of the method, usually an electrical signal representative of the capacitance detected by each capacitive sensor is processed by a processing device, which in turn produces electrical or optical signals representative of the position of the conductive object in relation to the touch sensor pad or touch sensor screen in the X and Y dimensions. A touch sensor strip, slider, or button operates on the same capacitance-sensing principle.
One type of touch sensor device operates on a principle known as self capacitance. Self capacitance refers to the capacitance between one electrode of a touch sensor device and ground. A number of self capacitance sensor devices may be arranged in a matrix to form a touch-sensor pad. As the size of the matrix increases, the number of self capacitance sensors increases along with the number of measurements for determining the presence of a conductive object. The increased number of measurements takes a longer amount of time to perform. The speed of the measurements can be increased by sampling the sensors in parallel, however, not all self capacitance sensors can support parallel sensing.
USPTO Backgrounds
USPTO Backgrounds