Atmel Corporation

Daniel Pickett

Martin John Simmons

Esat Yilmaz

Harald Philipp

Peter Timothy Sleeman

Darren Golbourn

Christopher Ard

Andrew Hersee

In certain embodiments, an apparatus comprises a charge-measurement capacitor and circuitry. The circuitry is configured to provide a pre-determined amount of charge to the charge-measurement capacitor and transfer an accumulated amount of charge on a sense electrode to the charge-measurement capacitor, the accumulated amount of charge having accumulated on the sense electrode due at least in part to noise. The circuitry is configured measure a voltage of the charge-measurement capacitor to determine the accumulated amount of charge.

Noise measurement in capacitive touch sensors

In one embodiment, a method includes receiving, by a controller coupled to a touch sensor, a plurality of signals from a plurality of sense electrodes, the plurality of signals indicative of an amount of capacitance between the touch sensor and an external object. The method further includes accessing a stored threshold value, determining a strength of a charge return path between the touch sensor and a ground, and adjusting the stored threshold value based on the determined strength of the charge return path. The threshold value indicates a threshold magnitude of the signals from the plurality of sense electrodes to process as a touch by the external object.

Touch sensor with adaptive touch detection thresholding

In one embodiment, a method includes sending a first set of signals to a first set of lines of a touch sensor. The method also includes receiving a second set of signals on a second set of lines of the touch sensor in response to sending the first set of signals. The second set of lines are capacitively coupled to the first set of lines. The method includes sending a third set of signals and receiving a fourth set of signals. The fourth set of signals is capacitively generated based on the third set of signals. The method also includes determining a fifth set of signals by compensating the second set of signals based on the fourth set of signals and determining whether a touch occurred based on the fifth set of signals.

Enhanced touch detection methods

A method of tracking multiple touches over time on a touch sensor, for example a capacitive touch screen. The method analyzes first and second touch data sets from adjacent first and second time frames. First, the touch data sets are analyzed to determine the closest touch in the second time frame to each of the touches in the first time frame, and calculating the separation between each such pair of touches. Then, starting with the pair of touches having the smallest separation, each pair is validated until a pairing is attempted between touches for which the touch in the second time frame has already been paired. At this point, the as-yet unpaired touches from the first and second touch data sets are re-processed by re-applying the computations but only including the as-yet unpaired touches. This re-processing is iterated until no further pairings need to be made. The method avoids complex algebra and floating point operations, and has little memory requirement. As such it is ideally suited to implementation on a microcontroller.

Multi-touch tracking

In a touch sensor, as well as providing touch position data, additional data is provided on the shape of the touch. This is achieved by having sampling nodes on a finer mesh than the size of the actuating object, typically a finger, so each finger touch activates a group of adjacent nodes on the sensor. In this way, each touch has a shape formed by the activated nodes. The shape allows the touch sensor to report an angle with each touch and data indicating how elongate the touch is, preferably both together as a vector in which the direction of the vector gives the angle and the magnitude of the vector gives the ellipticity. For each frame of data collected from the sensor array, the sensor outputs an (x, y) coordinate of touch position and a further (x, y) coordinate of a shape vector.

Two-dimensional touch sensors

In particular embodiments, an apparatus includes a charge-measurement capacitor having a first plate coupled to a second plate of a coupling capacitor and a non-transitory computer-readable storage medium embodying logic that is operable when executed to ground a first plate of the coupling capacitor; inject a pre-determined amount of charge onto the charge-measurement capacitor; and transfer an amount of charge accumulated on the second plate of the coupling capacitor to the first plate of the charge-measurement capacitor. The charge accumulated on the second plate of the coupling capacitor is due at least in part to noise. The logic is also operable when executed to determine, through a measured voltage across the charge-measurement capacitor, the amount of charge.

In a capacitive sensor of the type having X electrodes which are driven and Y electrodes that are used as sense channels connected to charge measurement capacitors, signal measurements may be made by driving the X electrodes to transfer successive packets of charge to the charge measurement capacitors. An additional noise measurement may be made by emulating or mimicking the signal measurement, but in certain embodiments without driving the X electrodes. The packets of charge transferred to the charge accumulation capacitor may be indicative of noise induced on the XY sensing nodes. These noise measurements can be used to configure post-processing of the signal measurements.

Noise handling in capacitive touch sensors

In a touch sensor, as well as providing touch position data, additional data is provided on the shape of the touch. This is achieved by having sampling nodes on a finer mesh than the size of the actuating object, typically a finger, so each finger touch activates a group of adjacent nodes on the sensor. In this way, each touch has a shape formed by the activated nodes. The shape allows the touch sensor to report an angle with each touch and data indicating how elongate the touch is, preferably both together as a vector in which the direction of the vector gives the angle and the magnitude of the vector gives the ellipticity. For each frame of data collected from the sensor array, the sensor outputs an (x, y) coordinate of touch position and a further (x, y) coordinate of a shape vector. This allows many novel gestures to be provided, such as single finger 'drag and zoom' and single finger 'drag and rotate'. It also allows for correction of systematic human error in the placement of finger touches on virtual keys.

In a capacitive sensor of the type having X electrodes which are driven and Y electrodes that are used as sense channels connected to charge measurement capacitors, signal measurements are made conventionally by driving the X electrodes to transfer successive packets of charge to the charge measurement capacitors. However, an additional noise measurement is made by emulating or mimicking the signal measurement, but without driving the X electrodes. The packets of charge transferred to the charge accumulation capacitor are then indicative of noise induced on the XY sensing nodes. These noise measurements can be used to configure post-processing of the signal measurements.

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Southampton, United Kingdom

Daniel Pickett