Elo Touchsystems, Inc.

Other

Tyco Electronics Corporation

Elo Touch Solutions, Inc.

Geoffrey D Wilson

Joel Christopher Kent

Joe Henry Babb

Robert J Adler

Jeffrey L Sharp

James Roney

Arie Ravid

Drew John Loucks

Mike Lewis

Victor E Borgnis

Michael Bruno Patti

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

A general method is described for producing an inexpensive touchscreen system that provides accurate positional information and compensates for manufacturing variations without complicated sensor arrangements. Utilizing a set of sensed signals that are unique to each location on the touchscreen sensor, equations for X and Y are derived via curve fitting methods. The coefficients of the equations are stored with the sensor. During touchscreen operation the coefficients are used to calculate X and Y to the desired accuracy directly and independently.

Algorithmic compensation system and method therefor for a touch sensor panel

A method and apparatus for discriminating against false touches in a touchscreen system is provided. The system is designed to confirm a touch registered by one touch sensor with another touch sensor, preferably of a different sensor type, prior to acting upon the touch (i.e., sending touch coordinates to the operating system). If the touch registered by the first touch sensor is not confirmed by the second touch sensor, the touch is invalidated. Thus the strengths of one type of sensor are used to overcome the deficiencies of another type of sensor. In one aspect, the secondary touch sensor comprises a force sensor to discriminate between true and false touches on other types of touch sensors, such as contaminants on optical and surface acoustic wave sensors, noise or weak signals on capacitive sensors, etc. The force sensor may be a simple one-element system that merely indicates that a touch has occurred or a multi-element system that can provide confirming or supplementary coordinate data. In another aspect, a capacitive sensor is used to confirm or veto touch data from optical, surface acoustic wave, and force sensors. As is the case with the secondary force sensor, a secondary capacitive sensor may be a simple discrete type or capable of providing touch coordinates in its own right. In a specific embodiment, one in which no touch overlay is used on a CRT monitor, the secondary touch sensor may employ the resistive coating on the surface of the CRT in combination with a current monitoring circuit that measures the amplitude of the electromagnetic noise signal coupled to the resistive coating. In this application when the screen is touched by a grounded object, the detected signal amplitude change exceeds a preset threshold thus indicating a valid touch.

Touch confirming touchscreen utilizing plural touch sensors

A method and apparatus for discriminating against false touches in a touchscreen system is provided. The system is designed to confirm a touch registered by one touch sensor with another touch sensor, preferably of a different sensor type, prior to acting upon the touch (i.e., sending touch coordinates to the operating system). If the touch registered by the first touch sensor is not confirmed by the second touch sensor, the touch is invalidated. Thus the strengths of one type of sensor are used to overcome the deficiencies of another type of sensor. This system is particularly well suited to meet the demands of an outdoor or semi-outdoor application. In one embodiment, one or more force sensors are used as the false touch sensor and a projective-capacitive sensor is used as the position coordinate determining sensor. In another embodiment, a projective-capacitive sensor is used as the false touch sensor. As the projective-capacitive sensor is only being used to provide touch confirmation, in this embodiment very few electrodes are required as well as minimal channel electronics. In another embodiment, both touch sensors are capable of providing accurate touch coordinates. In this configuration the system preferably determines which of the sensors is more likely to provide accurate information based on the circumstances.

Dual sensor touchscreen utilizing projective-capacitive and force touch sensors

Adaptive frequency touchscreen controller using intermediate-frequency signal processing

A method and apparatus for making a five-wire touch-screen compatible with a four-wire interface is provided. A non-microprocessor-based converter is used that can be integrated directly into the touch-screen housing or the screen-to-interface ribbon cable. In one aspect of the converter, an analog logic and switching element routes the reference voltage from the four-wire controller to a current injection control device. The current injection control device applies a constant current to the outermost screen member of the touch-screen. When the outermost screen member and the innermost screen member of the touch screen come into contact, the current from the outermost member is injected into the resistive coating of the innermost member at the point of contact. The injected current is distributed to the four contact electrodes of the innermost member in direct proportion to the coordinates of the point of contact. Each of the four currents is converted to a voltage and routed to a logic amplifier that outputs a pair of voltages proportional to the x- and y-coordinates of the compression point. In another aspect of the converter, a feedback circuit is provided that ensures that the voltages proportional to the x- and y-coordinates continuously track the reference voltage. As a result of this feedback circuit, the coordinate measurement system is both stable and reliable.

Low current four-wire interface for five-wire resistive touch-screen

Algorithmic compensation system and method therefor for a touch sensor

An improved touch sensor having a resistive surface and simplified corner electrodes for introducing electrical potentials into the resistive surface. Improved positional accuracy is achieved by selectively energizing the touch sensor transversely (either vertically or horizontally) and diagonally, in either direction. As a result, equipotential lines formed in this manner are nearly perpendicular to each other (from the two energizations) throughout a larger area of the touch sensor so that increased accuracy of position coordinates is achieved over this larger area. Provision is made to determine the quadrant of touch and to optimize the energization to achieve the increased accuracy in that particular quadrant of touch.

Growing community of inventors

Oxnard, CA, United States of America

Geoffrey D Wilson