Sawtooth Pulse Waveform Drive for Semiconductor Light Source Thermal Management
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Solution Overview
Problem
Semiconductor light sources, such as LEDs and semiconductor lasers, suffer from high deterioration and shortened lifespan due to heat buildup when operated at high temperatures for extended periods, affecting their luminance and efficiency in projector applications.
Innovation Solution
A light source device and projection method utilizing a plurality of semiconductor light source elements driven by a cyclic power signal with a sawtooth pulse waveform, where the crest value at the rise time is larger than at the fall time, to reduce thermal storage and maintain high luminous efficiency while controlling temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If semiconductor light source elements are operated at high temperature for high luminance, then light emission luminance is improved, but deterioration increases and lifespan is shortened
Solution Approach 1:
The patent applies periodic action by using a sawtooth pulse waveform for driving the semiconductor light source elements. The waveform periodically increases current during the rise time to achieve high luminance, then decreases current during the fall time to reduce heat accumulation. This periodic modulation allows the elements to operate at high luminance for short intervals while cooling down between pulses, thereby extending lifespan while maintaining brightness performance.
2Illumination intensity
If semiconductor light source elements are operated at high temperature for high luminance, then light emission luminance is improved, but heat buildup increases
Solution Approach 1:
The sawtooth pulse waveform implements periodic action by cyclically varying the drive current. During the rise time portion, high current provides high luminance; during the fall time portion, reduced current allows heat dissipation. This periodic modulation prevents sustained high temperature operation while maintaining peak luminance output.
Solution Approach 2:
The patent applies dynamics by making the drive current variable rather than constant. The sawtooth waveform dynamically adjusts the current level throughout the drive cycle, increasing it during the rise time for high luminance and decreasing it during the fall time for thermal management. This dynamic control optimizes both luminance output and temperature management.
3Illumination intensity
If semiconductor light source elements are operated at high temperature, then light emission luminance is improved, but power consumption increases
Solution Approach 1:
The sawtooth pulse waveform uses periodic action to concentrate power consumption into the rise time portion of the cycle when high luminance is needed. During the fall time portion, power consumption is reduced as the current decreases, allowing thermal management and reducing overall energy waste while maintaining peak luminance performance.
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
This approach extends the lifespan of semiconductor light source elements by maintaining lower maximum temperatures and enhancing luminous efficiency, allowing for higher light-emission luminance while reducing power consumption and prolonging the operational life of the elements.
Implementation Method 1
a plurality of semiconductor light source elements; and a drive control section configured to cyclically supply a power signal with a sawtooth pulse waveform... to each of the plurality of semiconductor light source elements by time division to thereby light-emission-drive the semiconductor light source elements
Implementation Method 2
the semiconductor light source has a drawback in that the semiconductor light source is easily subject to an influence of heat when it is operated at a high temperature for a long period of time
Data Source
AI summary
A light source device includes a plurality of semiconductor light source elements, and a drive control section configured to cyclically supply a power signal with a sawtooth pulse waveform in which a crest value at the rise time is larger than a crest value at the fall time to each of the plurality of semiconductor light source elements by time division to thereby light-emission-drive the semiconductor light source elements.