Atmel Corporation

Dilip Sangam

Hendrik Santo

Tushar Heramb Dhayagude

Kien Vi

Sean S Chen

Matthew D Schindler

Hong Zhang

Balaji Venugopal Virajpet

Ranajit Ghoman

Zhiyu Yang

Gurjit Thandi

Kevin Hempson

Anjan Sen

Manish S Kulkarni

Minjong Kim

Timothy James Herklots

Wenbo Liang

Ronald William Young

Sivaprakash Kannan

Klen Vi

The present invention discloses apparatus and techniques for modular backlighting control of a display. The display includes a number of strings of LEDs. The display is divided into several sections, and each section includes one or more strings of LEDs. A local controller is assigned to each section. The local controller receives feedback signals from the strings of LEDs in its sections and controls the drive voltages and drive currents of those strings. The local controllers communicate with each other and also with the main system controller.

Apparatus and technique for modular electronic display control

A controller circuit for the control of a power converter is disclosed. An example controller circuit generates a waveform that drives a switch that controls the power converter. The controller circuit includes a divider module that generates a modification factor based on a ratio of the two input signals of the module. The circuit includes a module that generates a first waveform configured for a critical conducting mode of operation of a power converter and an on-time adjuster module that modifies the first waveform based on the modification factor and generates a second waveform. The second waveform is delivered to the switch. An example modification factor is the ratio of the output voltage to the rectified input voltage of the power converter.

Low total harmonic distortion and high power factor correction power converters

A fault protection and correction circuit for the control of a power converter is disclosed. An example circuit generates a waveform that drives a switch on or off and controls the power converter. The controller circuit in addition to power factor correction (PFC) circuitry includes a first and a second shut down mode modules, both of them cause the switching to stop. The circuit includes a module for receiving fault events. When a fault occurs, the controller enters the second shut down mode. The controller stays in the second shut down mode if the required current for this mode can be provided by the outside circuitry. Otherwise, the controller enters the first shut down mode that requires less current and subsequently restarts the controller. By modifying the outside circuitry the controller can respond differently to fault events.

Fault protection and correction of line and load faults

A dual-mode circuit for the control of an AC/DC power converter is disclosed. An example dual-mode controller circuit generates a waveform that drives a switch on or off and controls the power converter. The controller circuit in addition to power factor correction (PFC) circuitry includes a critical conducting mode (CrM) module as well as a discontinuous conducting mode (DCM) module configured to generate waveforms adapted for CrM and DCM operation of a power converter. The circuit includes a node for receiving a feedback signal of a voltage or a current. Based on the received signal, one of the modules is selected at a time to supply the waveform at the output of the dual-mode controller. An example of the output waveform is a series of pulses that are configured to drive the switch that controls the transfer of power between input and output of the power converter.

Dual-mode, AC/DC power converter with power factor correction

System(s) and method(s) are provided for power management in an electronic display via compensation of a power source of a light-emitting-diode (LED) backlighting system. A compensation feedback loop includes a load-aware controller that receives the bad condition from a dimming controller and supplies a control signal to the power source. An efficiency regulator functionally connected the backlight circuitry closes the compensation, feedback loop and provides an input signal to the load-aware controller. The dimming controller implements phase-shifted pulse-modulation dimming, which based on duty cycle can establish a dimming equilibrium with two load conditions. The load aware controller includes a set of compensation blocks arranged in parallel, with a single compensation block connected to the input signal and that provides the control signal. A selector component in the load aware controller determines a compensation block to be connected to the compensation feedback loop based on the received load condition.

Load-aware compensation in light-emitting-diode backlight illumination systems

System(s) and method(s) are provided for regulation of gamma characteristic of a display having solid-state-based backlight illumination. Regulation of the gamma characteristic can be accomplished at least in part through synchronization of data writing to a set of pixels in a display within a video frame with backlight illumination of a region of the display during a predetermined period, wherein the region is spanned by the set of pixels. Collection of data indicative of illumination intensity of light to be emitted in a region of a backlight source of the display during the predetermined period enables determination of at least one gamma value and at least one gamma reference voltage related to the at least one gamma value. Application of the at least one gamma reference voltage to the set of pixels adjusts the gamma characteristic thereof within the video frame.

Regulation of gamma characteristic in a display

Integrated backlight unit (BLU) and liquid crystal systems and circuits in liquid crystal display (LCD) systems are described. An LCD system can include a BLU to emit light at different intensities, and a BLU controller coupled to the BLU and configured to control the intensities. An LCD unit can receive the emitted light, and emanate light at a selected luminosity. The LCD unit can include pixels corresponding to: a liquid crystalline medium to provide a transmittance of the light emitted or to transmit a color light; and transistors adapted to modulate reference voltages. An LCD unit controller can be coupled to the LCD unit and configured to control luminosity of the light emanated from the LCD unit. The BLU and the LCD unit, which can be integrated in a single integrated circuit, can be controlled during concurrent time periods for contrast enhancement of images displayed from the LCD unit.

Apparatus for integrated backlight and dynamic gamma/VCOM control on silicon chips

Systems, circuits and methods for phase-shifting pulse width modulated signal generation are disclosed. In some embodiments, a phase-shifting pulse width modulation circuit is configured to output pulses based on an input pulse width modulated signal. The pulses are staggered relative to one another, and can be received by a light-emitting diode driver for driving a light-emitting diode string at one or more time periods. The phase-shifting pulse width modulation circuit can include a counter-based programmable delay subcircuit consisting of two counter-based programmable delay blocks.

Apparatus, circuit and method for automatic phase-shifting pulse width modulated signal generation

System(s) and methode s) are provided to regulate backlighting in a light emitting diode (LED)-based display through a sequence of alternate pulse-width-modulation (PWM) frame or sub-frame insertions. Alternate PWM frames or sub-frames can be black or non-black. A plurality of pixels in the display is partitioned into at least one zone including one or more rows of pixels; the at least one zone determines sub-frame period based on refresh frequency of the display. A sequence of alternate PWM sub-frames includes at least one alternate sub-frame and at least one normal sub-frame. Alternate PWM frames or alternate PWM sub-frames include a phase delay during which a backlight unit is turned off, and a PWM sequence in which the backlight unit is turned on with a finite duty cycle for the remainder of the PWM frame or sub-frame.

Control of light-emitting-diode backlight illumination through frame insertion

The present invention relates to circuits and methods for limiting the operating area of a transistor in a constant current source. The circuits and methods use a detector and a driver to limit the operating area of a transistor. The detector and driver have parameters selected so that, when the voltage at the drain of the transistor satisfies a reference condition, the driver causes drain current of the transistor to decrease. The reference condition is determined relative to the maximum safe drain-to-source voltage at the design drain current of the constant current source.

Method and circuit for an operating area limiter

System(s), apparatus(es), and method(s) are provided for control of quality of light emitted from a group of solid-state light (SSL) sources that are part of an illumination fixture. The control is based at least in part on regulation of the spectral power distribution (SPD) of the light to match a SPD of a reference light source. A spectroscopic analyzer collects electromagnetic (EM) radiation emitted from the group of SSL sources and EM radiation substantially emitted from the reference light source. A first controller analyzes spectroscopic data related to SPDs of the group of SSL sources and the reference light source and, based on the analysis issues a configuration of the group of SSL sources. Implementation of the configuration causes the group of SSL sources to emit EM radiation with a SPD that nearly matches the SPD of the EM radiation substantially emitted from the reference light source.

Quality assurance of a solid-state illumination source

The present invention involves an electrical system in which an analog signal channel passes through various integrated circuit chips (ICs). The channel can carry one or more analog signals. Each IC can modify the signal(s) passing through it and pass it on to another IC or system component. The channel can be programmable. Each IC can include a comparator or a multiplexor to receive the channel signal from another IC or system component and to modify the received signal before transmitting it to another IC or system component. The comparator or the multiplexor can be programmable and can be selectively configured to compare the incoming signal from the channel with a variety of other signals and thresholds, or to simply act as a flow through gate and allow the signal to pass without any modification. The comparison can determine the output of the comparator. The operation and programming of the comparators, the multiplexors and the channel can be centrally controlled by a system controller, can be independently controlled by the ICs, or a combination thereof.

Architecture and technique for inter-chip communication

The present invention relates to circuits and methods for controlling one or more LED strings. The circuit comprises a programmable controller coupled to one or more detectors, wherein the one or more detectors are configured to detect one or more measurable parameters of one or more LEDs or LED drivers. The controller is configured to receive information from the one or more detectors related to the one or more measurable parameters and use that information to determine the desired drive voltage for the LED strings. The controller is associated with a power supply having power factor correction (PFC) capability. The controller provides the power supply with a control signal indicative of the desired drive voltage for one or more LED strings. The power supply also receives ac voltage and current waveforms as inputs and performs power factor correction and rectified waveforms related to the ac waveforms. The power supply generates the desired drive voltage based on the control signal.

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Saratoga, CA, United States of America

Dilip Sangam