Compaq Computer Corporation, Inc.

Texas Instruments Corporation

Hewlett-Packard Development Company, L.p.

Michael W Edwards

Scott W Dalton

Scott W Briggs

Stephen D Burleigh

Kenneth J Haugen

A system includes a capacitively-coupled touch sensor having a conductive first layer and a conductive second layer on a first insulative layer. The width of the second layer varies along an axis of the first layer. A first excitation signal is applied to one of the first and second layers and is capacitively coupled through a touch element to the other layer, producing a first signal that produces a second signal which is digitized. Digitized peak values of the second signal are processed to compute a value for a touch element location. A conductive third layer can be placed on the opposite side of the first layer has width varying oppositely to the second layer. The first excitation signal is applied to the second layer and a non-overlapping second excitation signal is applied to the third layer. The resulting digitized peak values are processed to cancel errors due to variations.

Linear capacitively coupled touch sensor and method

A portable computing device includes at least three buttons and circuitry for sensing the pressing of at least three buttons, one being recessed, and in response to such sensing provides a battery disable signal to a non-removable battery. The portable computing device further includes circuitry for sensing the coupling of the device to a device cradle, and in response to such coupling, or in response to the press of the recess button, provides a battery enable signal to the non-removable battery.

Battery disable/enable control circuitry of a portable computing device

An apparatus supports both (1) a cost-effective graphics device (such as an AGP device) integrated onto the motherboard, and (2) an upgradable computer system with an add-in card slot for receiving a second graphics device (such as a second AGP device) on a card. The apparatus is connected to a bus that has a first set of signals which is sensitive to noise. The apparatus also has a first switch connected to a first device, the first switch being connected to the first set of signals on the bus. The apparatus has a second switch which is adapted to be connected to a second device. The second switch is also connected to the first set of signals on the bus. The apparatus also has a detector connected to the first and second switches to enable the first switch if the first device is selected and otherwise enable the second switch.

System for reducing noise in bus having plurality of first and second

An LCD precharge regulator circuit providing current directly from the input battery voltage to precharge the LCD display. A first switch activates a precharge regulator coupled to the unregulated DC input voltage, to supply the power for the initial current surge from the DC input to charge the LCD display. The precharge regulator includes a transistor and a biasing circuit. The biasing circuit initially turns the transistor fully on, but increasingly biases the transistor off as the LCD display charges to just below the operating voltage of the LCD display. A delay circuit activates a second switch after the LCD display is substantially charged, where the second switch connects the supply voltage from the DC/DC converter to the LCD display. At that point, the transistor is biased off, isolating the LCD display from the DC input voltage. Thus, the supply voltage need only sustain the charge on the LCD display after being substantially charged. Low power series resistors are provided to serve as a fuse, which fail to an open circuit condition, isolating the LCD display from high input voltage levels in the event of excessive current flowing into an overvoltage Zener diode.

Growing community of inventors

Houston, TX, United States of America

Michael W Edwards