Elo Touchsystems, Inc.

Other

Paulo Irulegui Gomes

Joel Christopher Kent

James L Aroyan

Shigeki Kambara

Daniel H Scharff

Hiroshi Kaneda

Arie Ravid

Michael LeRoy Lewis

Michelle Ocampo

Robert De Renzi

Marcia M Davis-Cannon

An acoustic touchscreen ( ) has transmitting transducers ( ) for generating acoustic signals which are deflected across a touch-sensitive area ( ) by an array of partially acoustically reflective elements . A touch on the touch-sensitive area causes a perturbation in the acoustic signals. After traversing the touch-sensitive area, the acoustic signals are redirected by another array of partially acoustically reflective elements , towards receiving transducers ( ), where the signals (and any perturbations) are sensed. To accommodate touchscreens having narrow border regions ( ), the acoustic signals are propagated across the border regions using acoustic waveguides ( ). The waveguide confines the acoustic signals to traveling along a narrow path width, but yet permit them to be deflected across the touch-sensitive area. In this manner, the transducers and reflective elements can in turn be of narrower construction and can fit within narrow border regions.

Acoustic touchscreen having waveguided reflector arrays

A method and apparatus for adapting an acoustic touchscreen controller to the operating frequency requirements of a specific touchscreen are provided. The adaptive controller can either utilize look-up tables to achieve the desired output frequency or the it can use a multi-step process in which it first determines the frequency requirements of the touchscreen, and then adjusts the burst frequency characteristics, the receiver circuit center frequency, or both in accordance with the touchscreen requirements. In one embodiment, the adaptive controller compensates for global frequency mismatch errors. In this embodiment a digital multiplier is used to modify the output of a crystal reference oscillator. The reference oscillator output is used to control the frequency of the signal from the receiving transducers and/or to generate the desired frequency of the tone burst sent to the transmitting transducers. In another embodiment that is intended to compensate for both global and local frequency variations, the adaptive controller uses a digital signal processor. The digital signal processor, based on correction values contained in memory, defines a specific center frequency which preferably varies according to the signal delay, thus taking into account variations caused by localized variations in the acoustic wave reflective array. In yet another embodiment, a non-crystal local oscillator is used to provide the reference signal in the adaptive controller. The use of such an oscillator allows the controller to be miniaturized to a sufficient extent that it can be mounted directly to a touchscreen substrate. A feedback loop is used to compensate for oscillator drift. A discriminator circuit determines the degree of deviation from the desired frequency. The output from the discriminator is used to adjust the frequency of the local oscillator such that it tracks the frequency of the touchscreen.

Adaptive frequency touchscreen controller employing digital signal processing

A position touch sensor having a substrate and a resistive layer disposed on the substrate. At least one pair of electrodes is positioned on the resistive layer. A portion of one electrode is spaced from a portion of another electrode to produce an overlapped resistive region between the spaced portions of the electrodes. An insulating region extends into and terminates in the overlapped resistive region from a resistive region of the resistive layer outside the overlapped resistive region. A method for controlling the flow of current through a resistive layer for converting physical position information on the resistive layer into electrical signals. The method includes determining a dimension of a length of a generally continuous resistive section which is to be located in the resistive layer. The dimension of the length is determined through the use of electrical excitation in the resistive layer. A first insulating region is disposed in the resistive layer to form a first boundary of the generally continuous resistive section. Subsequently and at a distance from the first insulating region essentially equaling the dimension of the length, a second insulating region is disposed in the resistive layer to form a second boundary of the generally continuous resistive section such that current may be conducted through the generally continuous resistive section between the first and second insulating regions.

Touch sensitive screen and method

An acoustic wave touch sensor comprising an acoustic wave transducer, for transducing an acoustic wave; a substrate, having a front surface. A surface bound acoustic wave interface, having at one least bevel edge, is provided, having an transmitted acoustic wave signal attenuation of less than about 3 dB. The acoustic wave transducer is mounted to transmit the acoustic wave through the interface into the substrate, so that the energy of the acoustic wave appears at the surface. The acoustic wave transducer is mounted on a beveled region of the substrate, inclined to the front surface. The beveled edge has an effective radius which is small as compared to the wavelength and a bevel angle such that the acoustic wave is attenuated by less than about 3 dB on transmission across the edge. In this manner, means are provided to recess transducers for improved product robustness and compactness of design.

Gentle-bevel flat acoustic wave touch sensor

Growing community of inventors

Redwood City, CA, United States of America

Paulo Irulegui Gomes