Philips Electronics North America Corporation

North American Philips Corporation

U.S. Philips Corporation

Marvellworld Trade Ltd.

Marvell International Limited

Stephen L Wong

Naveed Majid

Yuan-Pin Yu

Satyendranath Mukherjee

Wei Lu

Mark B Hoffberg

Jose M Garcia

Sreeraman Venkitasubrahmanian

Tri Le

William Mai

Paul R Veldman

Sifen Luo

Wen-Jian Gu

Gregory T DiVincenzo

Howard B Pein

Mehran Moshfeghi

Robert A Glicksman

Vinit Jayaraj

Eugene J De Mol

Li Yushan

Zhouyuan Shi

Fred Prior

Paulo Caldiera

Rafael Aquino

Jun Wang

System and methods are provided for driving one or more light emitting diodes (LEDs) to reduce audible noise. An example system includes a switching component, a system controller, and a current generator. The switching component is configured to receive a dimming signal with a predetermined dimming frequency and configured to switch on or off the one or more LEDs in response to the dimming signal, the predetermined dimming frequency being outside a frequency band of the audible noise. The system controller is configured to receive a feedback signal related to a LED current that flows through the one or more LEDs and configured to generate a drive signal. Additionally, the current generator is configured to receive the drive signal, to generate a charging current to store energy during a charging period and to generate the LED current during a discharging period.

Systems and methods for driving light emitting diodes

In one embodiment the present invention includes a voltage regulator circuit comprising a voltage to current converter. The voltage to current converter is coupled to provide a current to maintain an output voltage under changing load conditions. A transconductance of the voltage to current converter is independent of the output current and therefore improves stability for the voltage regulator across load conditions.

Constant GM circuits and methods for regulating voltage

A low cost half bridge driver IC fabricated in the process technology with a minimum or reduced number of masking steps to implement all the blocks and without the use of the low threshold voltage CMOS. The half bridge driver IC uses a universal 12 Volt supply for all of the blocks with reference to the ground or to the half bridge output. Furthermore, the low differential current from high voltage level shifter transistors of the half bridge driver IC can provide enough voltage swing to set or reset the latch when high threshold voltage DMOS transistors are used in the pulse filter.

Low cost half bridge driver integrated circuit with capability of using high threshold voltage DMOS

This invention relates to an object-oriented system and method for easily and rapidly distributing medical images from existing picture and report storage systems to a plurality of heterogeneous client workstations. The system includes one or more interface engines, for providing image objects with uniform structure regardless of the type of existing system on which they are stored, and image server middleware, for managing the distribution of image objects. The system also includes a security object server, for authorizing user access to the image distribution system and to particular objects, a personalization object server, for providing user interface preferences and client workstation capabilities, and a web server, for downloading initial access pages and user interface components. The system implements a method for medical image distribution according to which image data stored in existing picture storage systems is first converted into a uniformly structured image objects before being composed for downloading to client workstations for user viewing. The system and method of this invention are easily extensible both for added function and for added performance. The system and method of this invention are preferably implemented according to CORBA standards.

Computer-based medical image distribution system and method

A Web-based authentication system and method, the system comprising at least one Web client station, at least one Web server station and an authentication center. The Web client station is linked to a Web cloud, and provides selected biometric data of an individual who is using the Web client station. The Web server station is also linked to the Web cloud. The authentication center is linked to at least one of the Web client and Web server stations so as to receive the biometric data. The authentication center, having records of one or more enrolled individuals, provides for comparison of the provided data with selected records. The method comprises the steps of (i) establishing parameters associated with selected biometric characteristics to be used in authentication; (ii) acquiring, at the Web client station, biometric data in accordance with the parameters; (iii) receiving, at an authentication center, a message that includes biometric data; (iv) selecting, at the authentication center, one or more records from among records associated with one or more enrolled individuals; and (v) comparing the received data with selected records. The comparisons of the system and method are to determine whether the so-compared live data sufficiently matches the selected records so as to authenticate the individual seeking access of the Web server station, which access is typically to information, services and other resources provided by one or more application servers associated with the Web server station.

Web-based, biometric authetication system and method

The server includes a layer for dynamically generating web pages and other data objects using scripts, such as graphic, audio and video files, in dependence on stored information indicating the user's needs and preferences, including those presumed from stored information as to the user's function, job, or purpose for being at the hospital, and logged usage profiles, the level of the user's access privileges to confidential patient information, and the computer and physical environments of the user. Notably, the content is generated in dependence on the display resolution and lowest bandwidth link between the server and browser to limit the waiting time for downloads as well as the server load.

Personalizing hospital intranet web sites

A switched bridge circuit includes a low voltage to high voltage interface which selectively controls an input to a high side switch. A controller compares the voltage across the interface, the state of the high side switch, and the output of the circuit. If hard switching is detected by the controller, it latches the voltage across the interface thus keeping the high side switch on to allow the hard switching to occur. If soft switching is detected, the high side switch is kept off. A source follower is used to drive the high side switch so that the circuit output follows the interface output thereby avoiding oscillation. A falling edge detector for the output of the circuit uses the inherent parasitic capacitance of a high voltage device which also forms a bootstrap diode. When the output drops, the parasitic capacitance feeds a resistance which causes a driver to actuate. A second falling edge detector uses the inherent parasitic capacitance of the level shifter switch which is another high voltage device. When the output drops, the parasitic capacitance turns on a switch. A rising edge detector also uses the inherent capacitance of the low voltage to high voltage interface. A switch is coupled to the circuit output and the low voltage to high voltage interface. When the circuit output rises, the switch actuates.

Level shifter

Web-based biometric authentication system and method

A high-frequency power amplifier circuit offers the advantages of high input impedance, good linearity, high power efficiency and accurate bias current control in a compact and economical circuit configuration. The amplifier includes a single-ended output stage driven by a symmetrical push-pull emitter follower stage with both active pull-down and active pull-up capability. The emitter follower stage is driven by an active phase-splitter stage, with bias current for the phase-splitter stage and subsequent stages being provided by a bias-current control stage which is directly connected to the phase splitter stage. A linear voltage-to-current converter stage receives a high-frequency input voltage and provides a high-frequency current signal to the input terminal of the bias-current control stage that controls the current in the output stage.

Linear high-frequency amplifier with high input impedance and high power

A high-frequency power amplifier circuit offers the advantages of high input impedance, high power efficiency and accurate bias current control in a compact and economical circuit configuration. The amplifier includes a single-ended output stage driven by a symmetrical push-pull emitter follower stage with both active pull-down and active pull-up capability. The emitter follower stage is driven by an active phase-splitter stage, with bias current for the phase-splitter stage and subsequent stages being provided by a bias-current control stage which is isolated at high frequencies from the high-frequency input signal to the amplifier.

High-frequency amplifier with high input impedance and high power

A high-voltage AC to low-voltage DC converter includes a rectifier circuit for providing a pulsating high-voltage DC signal from the high-voltage AC input and a switch having its main current path coupled between the rectifier circuit output and an output terminal of the converter. A filter capacitor is coupled to the output terminal to filter the low-voltage DC output, and first and second voltage sensors are coupled to the rectifier output and the low-voltage DC output terminal of the converter circuit, respectively. The first voltage sensor is set to sense a low (typically zero) voltage, and the second voltage sensor is set to sense the desired low-voltage DC output level. The outputs of the first and second voltage sensors are coupled to the set and reset inputs, respectively, of a latch circuit, with the output of the latch circuit being coupled to a control terminal of the switch in order to turn on the switch upon receiving a set input from the first voltage sensor and then turn off the switch on receiving a reset input from the second voltage sensor. This converter configuration provides a compact and highly-efficient circuit.

High-voltage AC to low-voltage DC converter

An inductorless voltage biasing circuit is provided for an AC-coupled amplifier of the type having a signal input terminal and a coupling capacitor for coupling the input terminal to a control terminal of the AC-coupled amplifier. The voltage biasing circuit includes a voltage source coupled to the control terminal, with the voltage biasing circuit including a differential-input amplifier having a noninverting input coupled to the voltage source, an inverting input, an output terminal and a differential voltage gain characteristic that decreases as a function of frequency. A resistor is coupled between the inverting input and the output terminal, and the control terminal of the AC-coupled amplifier is coupled to the inverting input of the differential-input amplifier. In this manner, a low-impedance DC-voltage biasing source is provided for an AC-coupled amplifier without using an inductor.

Inductorless voltage biasing circuit for and Ac-coupled amplifier

In a circuit arrangement including a pair of transistors serially connected together in a totem pole arrangement for bridging two buses at different voltage potentials, a driving scheme for controlling the conductive state of one of the pair of transistors. The scheme includes sensing the voltage difference across this one transistor by comparing a substantially fixed level represented by the voltage potential at one bus to a varying level. The varying level is based on the voltage at a junction joining the two transistors together. When the sensed voltage is at or below a predetermined level this one transistor is turned on.

Driving scheme for a bridge transistor

An integrated half-bridge timing control circuit for driving a half-bridge output stage has high-side and low-side power transistors coupled together at a high-voltage output terminal, and a bistable circuit for generating a high-side timing control waveform. The bistable circuit is driven by two delay circuits, each of which is decoupled from the high-side voltage by an associated interface circuit. The interface circuits are driven by input voltages which are delayed with respect to each other and which are referenced to the low side (ground). In this manner, an integrated half-bridge timing control circuit is obtained which is capable of operating at high frequencies with little power loss, which can be easily integrated, and which is both accurate and easily adjustable in operation.

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Scarsdale, NY, United States of America

Stephen L Wong