AC LED Array with Segmented Switching and Delay Phosphor
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Solution Overview
Problem
Conventional light-emitting devices connected directly to an AC power source experience flicker effects and reduced light emission time due to simultaneous on/off operation of LEDs, leading to inefficient power usage and potential damage from reverse currents.
Innovation Solution
A light-emitting device with an array of LEDs connected in series, utilizing switching blocks to sequentially turn on and off the LEDs based on AC voltage levels, maintaining a constant current flow and improving light-emitting efficiency, and incorporating a delay phosphor to extend light emission time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If light emitting cells are connected in series and operated simultaneously under AC voltage, then the device can be driven by AC power source, but the light emission time is shortened and flicker effect occurs
Solution Approach 1:
The array of light emitting cells is divided into multiple sub-arrays, where each sub-array contains a portion of the total light emitting cells. These sub-arrays are connected in parallel to each other while maintaining series connection within each sub-array. This segmentation allows different sub-arrays to be activated at different times during the AC cycle, thereby extending the overall light emission duration and reducing flicker effects.
2Power
If AC voltage exceeds sum of threshold voltages, then current flows through light emitting cells, but simultaneous on/off operation reduces effective light emission time
Solution Approach 1:
The patent implements periodic activation of different sub-arrays during the AC voltage cycle. By controlling the switching timing, each sub-array is activated during specific voltage intervals, creating a continuous or overlapping light emission pattern that extends the effective light emission time beyond what a single array could achieve.
3Duration of action of moving object
If high peak driving voltage is used to increase effective time, then light emission time increases, but power consumption in external resistor increases and current increases
Solution Approach 1:
By segmenting the array into multiple sub-arrays connected in parallel, the patent enables different subsets of light emitting cells to operate at different times. This allows the system to maintain adequate light output over extended periods without requiring excessive peak voltage, thereby reducing power consumption in external resistors and improving overall energy efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution prevents flicker effects, increases light emission time, and reduces power consumption by maintaining a constant current flow, thereby enhancing light-emitting efficiency and reducing eye fatigue.
Implementation Method 1
A light emitting diode (LED) is an electroluminescence device having a structure in which an N-type semiconductor and a P-type semiconductor are joined together, and emits light through recombination of electrons and holes
Implementation Method 2
incorporating a delay phosphor to extend light emission time
Data Source
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AI summary
Disclosed is an improved light-emitting device for an AC power operation. The light-emitting device for an AC power operation, comprises an LED chip having a plurality of light emitting cells; a transparent member for covering the LED chip; and a delay phosphor excited by light emitted from the light emitting cells to emit light in a visible light range.