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LED-driver appts.

A technology of LED driver and LED array, applied in lighting devices, electric solid-state devices, semiconductor devices, etc., can solve problems such as hindering noise signals, intensity control and loss of accuracy

Inactive Publication Date: 2008-11-05
SIGNIFY HLDG BV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This degradation can include loss of intensity control and precision, in addition to generating noisy signals that can hinder sampling strategies

Method used

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  • LED-driver appts.
  • LED-driver appts.
  • LED-driver appts.

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Experimental program
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Embodiment Construction

[0014] According to a preferred embodiment of the present invention, the non-linear sample and hold circuit allows for accurate measurement and calibration of the LED current signal so that the drive signal 18 follows precisely without excessive voltage and current overshoot and performance degradation.

[0015] figure 2 An exemplary LED driver configuration 28 according to a preferred embodiment of the present invention is shown. The amplified sense signal 30 is applied to an exemplary wave-shaping impedance combination of diode 32 , capacitor 34 , resistor 36 , and the drain of a MOSFET switching device 38 whose input gate is controlled by an input voltage signal 40 . A second MOSFET switching device 42 is also controlled by an input signal 40 through a logic inverter 44 . The second switching device 42 provides a current sinking circuit through a resistor 46 connected to the output of an amplifier 48 and the gate of the transistor 22 . Similar to the figure 1 Amplifier ...

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PUM

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Abstract

The invention relates to a LED-driver apparatus for controlling voltage and current in a switched LED array. The LED array is energized via a switched voltage converter, comprising: a semiconductor switching device activating the LED array during an activation time; current detecting means generating a signal proportional to the current through the LED array, during the activation time, and sample and hold means for retaining the detected signal outside the period of the activation time. In a further embodiment the apparatus comprises synchronizing means for aligning the activation time of the LED array to the activation time of the switching converter.

Description

technical field [0001] The present invention relates to the field of LED driving circuits, and more particularly to an LED driver device for driving an LED array using a sample and hold method in order to obtain a square wave PWM current waveform required by an LED load. Background technique [0002] Conventional LED array driver circuits typically use inexpensive linear voltage regulators to provide V cc The biasing rail acts as the energy source for the LEDs to be displayed. When an LED is selected for emitting light, a semiconductor switching device such as a transistor is activated to provide a current path through the selected LED. At the end of the display period, the device is turned off. An obvious disadvantage of this voltage driving scheme is that, due to the continuous conduction of the power regulator at the turn-off instant, there will be a voltage overshoot at the moment of turning off the switching device. This event body provides a situation where the bulk...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01L27/32H01L33/00H05B44/00
CPCH05B33/0845H05B33/0818Y02B20/347Y02B20/30H05B45/385H05B45/3725H05B45/39
Inventor C·张B·克劳伯格
Owner SIGNIFY HLDG BV