Methods and systems for processing touch inputs are disclosed. The invention in one respect includes reading data from a multipoint sensing device such as a multipoint touch screen where the data pertains to touch input with respect to the multipoint sensing device, and identifying at least one multipoint gesture based on the data from the multipoint sensing device.

Gestures for touch sensitive input devices

Apparatus and methods are disclosed for simultaneously tracking multiple finger (202-204) and palm (206, 207) contacts as hands approach, touch, and slide across a proximity-sensing, compliant, and flexible multi-touch surface (2). The surface consists of compressible cushion (32), dielectric electrode (33), and circuitry layers. A simple proximity transduction circuit is placed under each electrode to maximize the signal-to-noise ratio and to reduce wiring complexity. Scanning and signal offset removal on electrode array produces low-noise proximity images. Segmentation processing of each proximity image constructs a group of electrodes corresponding to each distinguishable contacts and extracts shape, position and surface proximity features for each group. Groups in successive images which correspond to the same hand contact are linked by a persistent path tracker (245) which also detects individual contact touchdown and liftoff. Classification of intuitive hand configurations and motions enables unprecedented integration of typing, resting, pointing, scrolling, 3D manipulation, and handwriting into a versatile, ergonomic computer input device.

Method and apparatus for integrating manual input

In linear IC's fabricated in a low-voltage CMOS technology, the reduction of the dynamic range due to the dc offset and low frequency noise of the amplifiers becomes increasingly significant. Also, the achievable amplifier gain is often quite low in such a technology, since cascoding may not be a practical circuit option due to the resulting reduction of the output signal swing. In this paper, some old and some new circuit techniques are described for the compensation of the amplifier's most important nonideal effects including the noise (mainly thermal and 1/f noise), the input-referred dc offset voltage as well as the finite gain resulting in a nonideal virtual ground at the input.

Circuit techniques for reducing the effects of op-amp imperfections: autozeroing, correlated double sampling, and chopper stabilization

A user interface method is disclosed. The method includes detecting a touch and then determining a user interface mode when a touch is detected. The method further includes activating one or more GUI elements based on the user interface mode and in response to the detected touch.

Mode-based graphical user interfaces for touch sensitive input devices

Proximity based systems and methods that are implemented on an electronic device are disclosed. The method includes sensing an object spaced away and in close proximity to the electronic device. The method also includes performing an action in the electronic device when an object is sensed.

Proximity detector in handheld device

A switched-capacitor interface for a capacitive pressure sensor is developed which provides a linear digital output. It consists basically of a sample/hold circuit followed by a charge-balancing analog-to-digital converter. The sensor capacitance changes hyperbolically with an applied pressure. To convert the nonlinear capacitance change into the linear digital output, two linearization methods are investigated. In either method, a linear digital output with an accuracy higher than 8-b is obtained. Because of its high-accuracy capability and compatible fabrication process, the interface described is best suited for a smart silicon capacitive pressure sensor. >

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A switched-capacitor interface for capacitive pressure sensors

A digital hygrometer using a relative humidity sensor is developed. The sensor consists of a polyimide film spin-coated onto an Si substrate. The sensor model for signal processing, which describes the sensor capacitance in terms of relative humidity and temperature in closed form, is derived first. The interface appropriate for the sensor model, based on a relaxation oscillator, is designed next. Finally, a prototype hygrometer built using a one-chip microprocessor and its performance are described to demonstrate the validity of the sensor model and interface.

A digital hygrometer using a polyimide film relative humidity sensor

An analog-to-digital converter is developed based on the charge-balancing principle. It consists of a switched-capacitor integrator, comparator, and digital logic circuit. Driven by the two phase clock, the integrator accumulates consecutively the incremental signal charge while extracting the quantized reference charge from the accumulated signal charge each time its output becomes positive, to keep their charge balance. The ratio between the accumulated and extracted frequencies for a given period of time then provides the digital representation of an input analog signal. A conversion accuracy higher than 14 bits can be expected from its integrated realization because the offset voltage and the finite open-loop gain of an op-amp and the parasitic capacitance have no effect upon the conversion process. It also features a small device-count integrate onto a very small chip area. Some applications are also presented to demonstrate its validity.

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A switched-capacitor charge-balancing analog-to-digital converter and its application to capacitance measurement

A resistance-to-frequency converter consisting of a Wheatstone bridge followed by an integrator and a comparator is described. In concept the circuit represents a relaxation oscillator whose frequency changes linearly with a resistance change detected by the bridge. Analyses show that a resolution better than 0.05% is possible with the simple configuration, and an excellent linearity is maintained over the wide resistance change by using a simple compensation method. The converter is therefore suited as a signal conditioner of a resistive sensor. Experimental results are included to demonstrate its performance.

A high-resolution, linear resistance-to-frequency converter

An interface for a capacitive pressure sensor which accommodates digital encoding and linearization functions has been developed. The front-end is a switched-capacitor bridge which converts the sensor capacitance into a proportional voltage. This voltage is applied to a pulse-width modulator to be compared with a model signal generated by a digital waveform synthesizer (DWS). This model-based signal processing provides the digital equivalent of the pressure being measured. For high-yield, monolithic implementation of the interface, oversampling /spl Delta/-/spl Sigma/ demodulation techniques are used for the DWS. In addition to the digital functions, offset and scale adjustment, and cross-parameter compensation are also possible with this architecture. A prototype interface is described to demonstrate these capabilities.

/pdf/a-capacitive-pressure-sensor-interface-using-oversampling-22sea71rd5.pdf

Kenzo Watanabe

Papers

A switched-capacitor interface for capacitive pressure sensors

A digital hygrometer using a polyimide film relative humidity sensor

A switched-capacitor charge-balancing analog-to-digital converter and its application to capacitance measurement

A high-resolution, linear resistance-to-frequency converter

A capacitive pressure sensor interface using oversampling /spl Delta/-/spl Sigma/ demodulation techniques