Texas Instruments Corporation

Ing-Yih James Wang

Wendy Xiaowen Fang

Herbert Braisz

Tony Chang

An apparatus comprises touch screen interface and signal processing circuit. Within touch screen interface, there are switching circuits configured to be coupled to at least one of a plurality of column electrodes, and there are touch detection circuits configured to be coupled to at least one of a plurality of row electrodes. The signal processing circuit is coupled to each switching circuit and each touch detection circuit so as to be able to selectively activate the plurality of switching circuits and touch detection circuits to identify a zone for a touch event. The signal processing circuit determines first, second, third, and fourth resistances for the zone for the touch event and determines a set of coordinates and pressure for the touch event from its first, second, third, and fourth resistances wherein an aperture filter register is in a host interface that also stores the first digital representation.

Aperature filtering for resistive multi-touch distortions

A 5-wire touch screen system includes a touch screen () including a wiper () and a resistive layer () aligned with the wiper and first (UL), second (UR), third (LR), and fourth (LL) resistive layer contacts, wherein a touch on the screen presses a small portion of the wiper against the resistive layer, producing a touch resistance (R) between them at a touch point on the resistive layer. The wiper and various contacts are selectively coupled to first (V) and second (GND) reference voltages, respectively, to generate an analog touch voltage (V) at the touch point. The wiper and various contacts are selectively coupled to an analog input () and a reference voltage input of an ADC () for converting the touch voltage (V) to a digital representation. Analog voltages (V) and (V) at the touch point are converted to corresponding digital representations by the ADC.

5-wire resistive touch screen pressure measurement circuit and method

A touch screen system includes a touch screen assembly () and a touch screen controller (A) coupled to terminals () of the touch screen assembly (), the touch screen controller (A) including a controller () and an analog to digital converter () for generating multiple digital data numbers representing multiple coordinate values, respectively, of a particular touch point (Q) of the touch screen assembly () in response to control signals () generated by the controller (). A sorting technique is performed to sort the digital data numbers in order of their values, respectively. An averaging technique is performed on at least some of the sorted digital data numbers, including a median sorted digital number.

Median and mean coherent filter and method for eliminating noise in touch screen controller

A touch screen controller (A) includes circuitry (B) for generating a pen touch detection signal (PENTOUCH) having a first level if a touch point (Q) of a touch screen assembly () including first () and second () resistive screens is detected, and generating a second level of the pen touch detection signal if a touch point is not detected. A controller (A) includes circuitry (A) that generates an interrupt signal (IRQ) to be sent to a host processor () in response to the first level of the pen touch detection signal and for resetting the interrupt signal (IRQ) in response to the second level of the pen touch detection signal if the second level is received before a convert command is received from the host processor. The interrupt signal (IRQ) represents an interrupt service request for a convert command from the host processor (). Resetting of the interrupt signal (IRQ) has the effect of canceling the interrupt service request.

Wait mode pen-touch detection and method for touch screen controller

A touch screen digitizing system includes a first resistive screen and a touch screen controller including an ADC and self-test circuitry having a driver switch coupled between a reference voltage and a first terminal of the first resistive screen, and a first test switch coupled between ground and a conductor connected to generate a first test voltage on the conductor indicative of connection resistance between the first resistive screen and the touch screen controller. Another test switch couples the test voltage to an input of the ADC. An output of the ADC is compared with a reference to determine whether the connection resistance is excessive. Connection resistance between a second resistive screen and the touch screen controller is measured similarly. Similar self-test circuitry operates to detect a short circuit between the first resistive screen and the second resistive screen.

Method and circuitry for self testing of connectivity of touch screen panel

A touch screen controller circuit (A) including means for generating a first and second levels of a pen touch signal (PENTOUCH) if a touch point (Q) is present or absent, respectively. A clock start signal (CLKSTART) is generated in response to the first level. An internal clock signal (INTCLK) is generated in response to the clock start signal. First and second levels of a synchronized pen touch signal (PENTOUCH) corresponding to the first and second levels, respectively, of the pen touch signal are generated in response to the internal clock signal. A stop clock signal (CLKSTOP) is generated in response to the second level of the synchronized pen touch signal. The internal clock signal (INTCLK) is stopped in response to the clock stop signal.

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Tucson, AZ, United States of America

Ing-Yih James Wang