Lsi Logic Corporation

Steven P Callicott

William K Petty

Mark S Snyder

Billy B Duncan

Mark S Miquelon

An apparatus detects the approach and touch-down of an object relative to a sensor panel. The apparatus includes a digital filter for determining a first derivative of a current flow in the sensor panel and a controller determines when the first derivative reaches a maximum. In a preferred embodiment, a magnitude for current flow in a plurality of corners of the sensor panel is determined by the controller. These magnitudes are then summed to determine a current flow from which the first derivative is computed. The current flow is analyzed by the controller to determine when an object is approaching the sensor panel, has contacted the sensor panel, and is withdrawn from the sensor panel. Thresholds are used to avoid false detection of approaching objects.

Method and apparatus for touch detection based on the velocity of an object relative to a sensor panel

A method and apparatus for determining when an approaching object has contacted a sensor panel. The method includes the steps of (a) using a controller which is connected to the sensor panel, (b) determining a value for the approaching object based on a current flow between the sensor panel and the controller, (c) repeating step (b) until the value has reached a maximum value, and (d) generating a signal when the value has reached the maximum value to indicate that the object is contacting the sensor panel.

Method and apparatus for touch detection based on the current flow

A device for electrically isolating an external device or internal device from an internal signal bus on a semiconductor substrate is disclosed. The device includes a set of drivers which couple an internal signal bus to an external signal bus and a set of drivers which couple the internal signal bus to an internal device signal bus. A driver enable signal generator generates a signal which enables one set of drivers to electrically couple the internal signal bus to either the external device signal bus or the internal device signal bus. The driver enable signal generator generates the driver enable signal in correspondence with the state of a signal indicating the presence or absence of an external device and a signal indicating whether a data transfer operation is occurring. If the external device is present and a data transfer operation is occurring, the internal signal bus is coupled to the external device signal bus. If an external device is not present and a data transfer operation is occurring, the internal device signal bus is coupled to the internal signal bus. In this manner, the electrically isolating device is capable of electrically isolating both internal and external devices from the internal signal bus except during I/O operations. The preferred embodiment uses a dual set of drivers to drive data signals from an internal data bus to either an internal device data bus or an external device data bus while a multiplexer and a single driver are used to electrically couple data from the internal data bus to either an internal device data bus or an external device data bus.

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Colorado Springs, CO, United States of America

Steven P Callicott