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Method and apparatus for controlling dimming levels of LEDs

A dimming and controller technology, applied in lighting devices, the use of semiconductor lamps, electroluminescent light sources, etc., to solve problems such as uneven light levels, low efficiency, and color shifts

Active Publication Date: 2015-04-01
SIGNIFY HLDG BV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Thus known shunt switches and methods of using them are relatively inefficient in applications involving dimming LEDs
Also, the efficiency (1m / W) of LEDs is higher at lower drive currents, so known PWM dimming methods are less efficient than known analog dimming methods
However analog dimming also has some disadvantages at low dimming levels
For example, if the LED current is less than approximately 5% and as much as 30% of the full output rating, the light level may be uneven from LED to LED, color shift may occur, and the efficiency of the LED is also relatively low at very low current levels. Difference
Additionally, the driver electronics become more difficult as current levels drop below 1%, offset voltage and electrical noise in the current sensing circuit become major concerns
These issues make analog dimming less than desired at dark levels below 0.1%

Method used

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  • Method and apparatus for controlling dimming levels of LEDs
  • Method and apparatus for controlling dimming levels of LEDs
  • Method and apparatus for controlling dimming levels of LEDs

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Embodiment Construction

[0026] In the following Detailed Description, for purposes of illustration and not limitation, representative examples disclosing specific details are set forth in order to provide a thorough understanding of the present teachings. Descriptions of well-known devices, materials, and fabrication methods may be omitted so as not to obscure the description of the example embodiments. Nonetheless, such devices, materials, and methods that are within the knowledge of one of ordinary skill in the art may be used in accordance with the representative embodiments.

[0027] figure 1 A simplified block diagram of a light emitting device 100 according to various embodiments of the invention is illustrated. The lighting device comprises a dimming circuit 101 that receives an input voltage, such as a line voltage. Dimming circuit 101 provides a specific drive current to LED 102 based on the desired dimmer setting. In one representative embodiment, the light emitting device may be provide...

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Abstract

Circuits useful in achieving efficient current control of LEDs based on a dimming control input are described. The circuits use a combination of PWM dimming and analog dimming to achieve a highly efficient LED driver over a wide range of dimming from near 0% to 100% light output.

Description

technical field [0001] The present invention generally relates to controlling dimming levels of light emitting diodes (LEDs). More specifically, various inventive methods and apparatus disclosed herein relate to controlling drive current above and below a threshold level. Background technique [0002] Digital lighting technology, ie lighting based on semiconductor light sources such as light emitting diodes (LEDs), offers a viable alternative to traditional fluorescent, HID and incandescent lamps. Functional advantages and benefits of LEDs include high energy conversion and optical efficiency, durability, lower operating costs, and many others. Recent developments in LED technology have provided efficient and robust full-spectrum light emitting sources that enable a variety of lighting effects in many applications. Some luminaires embodying these sources have lighting modules that include light emitting modules capable of producing different colors (e.g., red, green, and b...

Claims

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Application Information

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IPC IPC(8): H05B33/08H05B44/00
CPCY02B20/347H05B33/0815H05B33/0845H05B45/375H05B45/3725H05B45/395Y02B20/30H05B45/10H05B31/50
Inventor B·克劳伯格R·格瑞斯查A·施罗特里雅
Owner SIGNIFY HLDG BV