Abstract: Negative pixel compensation to compensate for a negative pixel effect in touch signal outputs due to poor grounding of an object touching the device is disclosed. To do so, the device can switch to a configuration to measure the grounding condition of the touching object and use the measurement to compensate the touch output values. In the switched configuration, a first set of lines of the device can be switched between a coupling to a stimulation signal input to drive the device, a coupling to a capacitance signal output to output a signal indicative of the object's grounding condition, and a coupling to ground. A second set of lines of the device can be coupled to a touch signal output to output a signal indicative of the object's touch at the device. The grounding signal can be applied to the touch signal to compensate for the negative pixel effect.

Abstract: Pre-stored no-touch or no-hover (no-event) sensor output values can initially be used when a sensor panel subsystem is first booted up to establish an initial baseline of sensor output values unaffected by fingers or other objects touching or hovering over the sensor panel during boot-up. This initial baseline can then be normalized so that each sensor generates the same output value for a given amount of touch or hover, providing a uniform response across the sensor panel and enabling subsequent touch or hover events to be more easily detected. After the initial normalization process is complete, the pre-stored baseline can be discarded in favor of a newly captured no-event baseline that may be more accurate than the pre-stored baseline due to temperature or other variations.

Abstract: Normalization of regions of a sensor panel capable of detecting multi-touch events, or a sensor panel capable of detecting multi-hover events, is disclosed to enable each sensor in the sensor panel to trigger a virtual button in a similar manner, given the same amount of touch or hover. Each sensor produces an output value proportional to the level or amount of touch or hover. However, due to processing, manufacturing and physical design differences, the sensor output values can vary from region to region or panel to panel for a given amount of touch or hover. To normalize the sensor output values across regions, gain and offset information can be obtained in advance, stored in nonvolatile memory, and later used to normalize the sensor output values so that all regions in the sensor panel can trigger virtual buttons similarly, providing a uniform “response function” at any location on the sensor panel.

Abstract: Normalization of regions of a sensor panel capable of detecting multi-touch events, or a sensor panel capable of detecting multi-hover events, is disclosed to enable each sensor in the sensor panel to trigger a virtual button in a similar manner, given the same amount of touch or hover. Each sensor produces an output value proportional to the level or amount of touch or hover. However, due to processing, manufacturing and physical design differences, the sensor output values can vary from region to region or panel to panel for a given amount of touch or hover. To normalize the sensor output values across regions, gain and offset information can be obtained in advance, stored in nonvolatile memory, and later used to normalize the sensor output values so that all regions in the sensor panel can trigger virtual buttons similarly, providing a uniform “response function” at any location on the sensor panel.

Abstract: A touch surface device having improved sensitivity and dynamic range is disclosed. In one embodiment, the touch surface device includes a touch-sensitive panel having at least one sense node for providing an output signal indicative of a touch or no-touch condition on the panel; a compensation circuit, coupled to the at least one sense node, for generating a compensation signal that when summed with the output signal removes an undesired portion of the output signal so as to generated a compensated output signal; and an amplifier having an inverting input coupled to the output of the compensation circuit and a non-inverting input coupled to a known reference voltage.

Abstract: Pre-stored no-touch or no-hover (no-event) sensor output values can initially be used when a sensor panel subsystem is first booted up to establish an initial baseline of sensor output values unaffected by fingers or other objects touching or hovering over the sensor panel during boot-up. This initial baseline can then be normalized so that each sensor generates the same output value for a given amount of touch or hover, providing a uniform response across the sensor panel and enabling subsequent touch or hover events to be more easily detected. After the initial normalization process is complete, the pre-stored baseline can be discarded in favor of a newly captured no-event baseline that may be more accurate than the pre-stored baseline due to temperature or other variations.

Abstract: Pre-stored no-touch or no-hover (no-event) sensor output values can initially be used when a sensor panel subsystem is first booted up to establish an initial baseline of sensor output values unaffected by fingers or other objects touching or hovering over the sensor panel during boot-up. This initial baseline can then be normalized so that each sensor generates the same output value for a given amount of touch or hover, providing a uniform response across the sensor panel and enabling subsequent touch or hover events to be more easily detected. After the initial normalization process is complete, the pre-stored baseline can be discarded in favor of a newly captured no-event baseline that may be more accurate than the pre-stored baseline due to temperature or other variations.

Abstract: A touch surface device having improved sensitivity and dynamic range is disclosed. In one embodiment, the touch surface device includes a touch-sensitive panel having at least one sense node for providing an output signal indicative of a touch or no-touch condition on the panel; a compensation circuit, coupled to the at least one sense node, for generating a compensation signal that when summed with the output signal removes an undesired portion of the output signal so as to generated a compensated output signal; and an amplifier having an inverting input coupled to the output of the compensation circuit and a non-inverting input coupled to a known reference voltage.

Abstract: Disclosed herein are liquid-crystal display (LCD) touch screens that integrate the touch sensing elements with the display circuitry. The integration may take a variety of forms. Touch sensing elements can be completely implemented within the LCD stackup but outside the not between the color filter plate and the array plate. Alternatively, some touch sensing elements can be between the color filter and array plates with other touch sensing elements not between the plates. In another alternative, all touch sensing elements can be between the color filter and array plates. The latter alternative can include both conventional and in-plane-switching (IPS) LCDs. In some forms, one or more display structures can also have a touch sensing function. Techniques for manufacturing and operating such displays, as well as various devices embodying such displays are also disclosed.

Abstract: A multi-touch capacitive touch sensor panel can be created using a substrate with column and row traces formed on either side of the substrate. To shield the column (sense) traces from the effects of capacitive coupling from a modulated Vcom layer in an adjacent liquid crystal display (LCD) or any source of capacitive coupling, the row traces can be widened to shield the column traces, and the row traces can be placed closer to the LCD. In particular, the rows can be widened so that there is spacing of about 30 microns between adjacent row traces. In this manner, the row traces can serve the dual functions of driving the touch sensor panel, and also the function of shielding the more sensitive column (sense) traces from the effects of capacitive coupling.

Abstract: A multi-touch capacitive touch sensor panel can be created using a substrate with column and row traces formed on either side of the substrate. To shield the column (sense) traces from the effects of capacitive coupling from a modulated Vcom layer in an adjacent liquid crystal display (LCD) or any source of capacitive coupling, the row traces can be widened to shield the column traces, and the row traces can be placed closer to the LCD. In particular, the rows can be widened so that there is spacing of about 30 microns between adjacent row traces. In this manner, the row traces can serve the dual functions of driving the touch sensor panel, and also the function of shielding the more sensitive column (sense) traces from the effects of capacitive coupling.

Abstract: Normalization of regions of a sensor panel capable of detecting multi-touch events, or a sensor panel capable of detecting multi-hover events, is disclosed to enable each sensor in the sensor panel to trigger a virtual button in a similar manner, given the same amount of touch or hover. Each sensor produces an output value proportional to the level or amount of touch or hover. However, due to processing, manufacturing and physical design differences, the sensor output values can vary from region to region or panel to panel for a given amount of touch or hover. To normalize the sensor output values across regions, gain and offset information can be obtained in advance, stored in nonvolatile memory, and later used to normalize the sensor output values so that all regions in the sensor panel can trigger virtual buttons similarly, providing a uniform “response function” at any location on the sensor panel.

Abstract: Pre-stored no-touch or no-hover (no-event) sensor output values can initially be used when a sensor panel subsystem is first booted up to establish an initial baseline of sensor output values unaffected by fingers or other objects touching or hovering over the sensor panel during boot-up. This initial baseline can then be normalized so that each sensor generates the same output value for a given amount of touch or hover, providing a uniform response across the sensor panel and enabling subsequent touch or hover events to be more easily detected. After the initial normalization process is complete, the pre-stored baseline can be discarded in favor of a newly captured no-event baseline that may be more accurate than the pre-stored baseline due to temperature or other variations.

Abstract: Negative pixel compensation in a touch sensitive device is disclosed. The device can compensate for a negative pixel effect in touch signal outputs due to poor grounding of an object touching the device. To do so, the device can switch to a configuration to measure the grounding condition of the touching object and use the measurement to compensate the touch output values from the device accordingly. In the switched configuration, a first set of lines of the device can be switched between a coupling to a stimulation signal input to drive the device, a coupling to a capacitance signal output to output a signal indicative of the object's grounding condition, and a coupling to ground. A second set of lines of the device can be coupled to a touch signal output to output a signal indicative of the object's touch at the device. In addition or alternatively, in the switched configuration, the first set of lines of the device can be switched to function as the second set of lines and vice versa.

Abstract: Improved capacitive touch and hover sensing with a sensor array is provided. An AC ground shield positioned behind the sensor array and stimulated with signals of the same waveform as the signals driving the sensor array may concentrate the electric field extending from the sensor array and enhance hover sensing capability. The hover position and/or height of an object that is nearby, but not directly above, a touch surface of the sensor array, e.g., in the border area at the end of a touch screen, may be determined using capacitive measurements of sensors near the end of the sensor array by fitting the measurements to a model. Other improvements relate to the joint operation of touch and hover sensing, such as determining when and how to perform touch sensing, hover sensing, both touch and hover sensing, or neither.

Abstract: Normalization of the built-in DC offset error in each analog channel is disclosed to reduce image distortion in multi-event (multi-touch or multi-hover) sensor panels. By eliminating the component-dependent offset error from each analog channel, each analog channel will generate approximately the same output value for a given dynamic input signal. Normalization can include “phantom row” compensation, which involves measuring the static output value of each analog channel when no stimulus is applied to any row of a multi-event sensor panel, and subtracting this value out of any subsequent output value generated by the analog channel. Normalization can also include DAC offset compensation, which involves setting the offset compensation voltage of each analog channel to some fraction of its normal value, measuring the output of the analog channel over temperature, determining a temperature coefficient, and adjusting any subsequent output value generated by the analog channel to account for this drift.

Abstract: Systems and methods for touch screens with integrated transparent conductive material resistors are provided. Metal traces on the surface of a touch screen may be subject to radio-frequency interference (RFI) that can adversely affect the performance of the touch screen. Transparent conductive material resistors inserted within the metal trace paths can be used to form low-pass filters which can reduce the affect of the RFI.

Abstract: A multi-touch sensor panel is disclosed that can include a glass subassembly having a plurality of column traces of substantially transparent conductive material that can be formed on the back side, wherein the glass subassembly can also act as a cover that can be touched on the front side. Row traces of the same or different substantially transparent conductive material can then be located near the column traces, and a layer of dielectric material can be coupled between the column traces and the row traces. The row and column traces can be oriented to cross over each other at crossover locations separated by the dielectric material, and the crossover locations can form mutual capacitance sensors for detecting one or more touches on the front side of the glass subassembly.

Abstract: A multi-touch sensor panel is disclosed that can be produced by forming a plurality of first traces of substantially transparent conductive material on a first substrate, forming a plurality of second traces of the substantially transparent material, and creating a fluid-tight gap between the plurality of first traces and the plurality of second traces. The fluid-tight gap can then be filled with a fluid having substantially no bubbles and an optical index similar to the optical index of the first and second traces to make the gap and the first and second traces substantially transparent. The second and first traces can be oriented to cross over each other at crossover locations separated by the fluid, the crossover locations forming mutual capacitance sensors for detecting touches.

Abstract: Normalization of the built-in DC offset error in each analog channel is disclosed to reduce image distortion in multi-event (multi-touch or multi-hover) sensor panels. By eliminating the component-dependent offset error from each analog channel, each analog channel will generate approximately the same output value for a given dynamic input signal. Normalization can include “phantom row” compensation, which involves measuring the static output value of each analog channel when no stimulus is applied to any row of a multi-event sensor panel, and subtracting this value out of any subsequent output value generated by the analog channel. Normalization can also include DAC offset compensation, which involves setting the offset compensation voltage of each analog channel to some fraction of its normal value, measuring the output of the analog channel over temperature, determining a temperature coefficient, and adjusting any subsequent output value generated by the analog channel to account for this drift.