1. Field of the Invention
Embodiments of the present invention generally relate to a system and method of sensing an input object's position over a sensing region of a proximity sensing device.
2. Description of the Related Art
Input devices including proximity sensor devices (also commonly called touchpads or touch sensor devices) are widely used in a variety of electronic systems. A proximity sensor device typically includes a sensing region, often demarked by a surface, in which the proximity sensor device determines the presence, location, and/or motion of one or more input objects. Proximity sensor devices may be used to provide interfaces for the electronic system. For example, proximity sensor devices are often used as input devices for larger computing systems (such as touchpads integrated in, or peripheral to, notebook or desktop computers). Proximity sensor devices are also often used in smaller computing systems (such as touch screens integrated in cellular phones or tablet computers).
A proximity sensor device may be integrated with a display device such that one or more types of electrodes are configured for both updating the display and transmitting input sensing signals. In such configurations, time must be divided between performing input sensing and updating display images with the shared electrodes (also called “common” electrodes).
Interference mitigation techniques used to ensure accurate input sensing typically require a minimum number of samples to be acquired per input sensing element for each input sensing cycle. However, because, in general, the time allocated to display updating cannot be changed, the non-display time periods available for performing input sensing cannot be significantly increased. Thus, in conventional configurations, there is a tradeoff between the number of samples acquired for each input sensing element and the resolution at which input sensing is performed—in order to increase the number of samples acquired per element per input sensing cycle, the number of sensing elements scanned during a given input sensing cycle must be decreased. Further, to decrease the number of input sensing elements, the size of each element must be increased, resulting in diminished spatial resolution and sensing accuracy.
Therefore, there is a need for increasing sensing performance without decreasing the resolution at which input sensing is performed.