Sense signals for touch panels
OwnerWilliam Martin SNELGROVEinventor
Life of this patent
Estimating the term…
Abstract
In capacitive touch panels arrays, self- and mutual capacitances of embedded sense lines in rows and columns are measured to estimate the position of probes such as fingers, styli and the like. Signals are driven onto the sense lines in order to estimate capacitances, but it is desired to keep these signals as weak as possible in order to minimize power consumption, voltage drive requirements and electromagnetic interference. Accurate detection of the position of the probe, particularly with weak signals, is rendered difficult by its motion. Techniques are proposed for power-efficient drive signals and related techniques proposed that are operable to estimate velocity. Dual receive structures with similar properties are proposed.
Claims20
A sensing system for measuring a position and a velocity of a probe, the sensing system comprising:
- a panel;
- a plurality of sense lines disposed in the panel, the plurality of sense lines configured to measure data associated with the probe;
- a driver circuit connected to the plurality of sense lines, the driver circuit configured transmit a plurality of drive signals at an initial frequency to the plurality of sense lines;
- a receiver circuit connected to the plurality of sense lines, the receiver circuit configured to receive a plurality of sensed signals, each sensed signal of the plurality of sensed signals being received from a sense line of the plurality of sense lines, wherein each sensed signal comprises a sensed phased and a sensed frequency;
- and
- a plurality of differencing circuits configured to phase-shift a signal associated with each sense line of the plurality of sense lines;
- a signal processing circuit connected to receive a plurality of processing signals associated with the plurality of sensed signals, the signal processing circuit configured to determine correlation components of each processing signal with an associated drive signal to calculate a position and a velocity of the probe.
A method of measuring a position and a velocity of a probe, the method comprising:
- transmitting, using a driver circuit, a plurality of drive signals to a plurality of sense lines;
- receiving, using a receiver circuit, a plurality of sensed signals, each sensed signal of the plurality of sensed signals being received from a sense line of the plurality of sense lines, wherein each sensed signal comprises a sensed phased and a sensed frequency;
- phase-shifting, using a plurality of differencing circuits, a signal associated with each sense line of the plurality of sense lines;
- determining, using a signal processing circuit, correlation components of each processing signal of a plurality of processing signals associated with the plurality of sensed signals;
- and
- calculating a position and a velocity of the probe using the correlation components of each processing signal of a plurality of processing signals.
Dependencies are inferred from the claim text.