White Balance Adjustment in Single DLP Projectors
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Solution Overview
Problem
The transition from gas discharge lamps to solid-state light (SSL) sources in projection display systems poses challenges in maintaining color balance and luminance, as SSL sources have different luminous flux ratios and radiant flux compared to traditional ultra high performance (UHP) lamps, leading to variations in white balance and luminance due to aging, temperature changes, and user preferences.
Innovation Solution
A method and apparatus that utilize a synchronization signal from the rotating color wheel to modulate the drive current of SSL sources in single DLP projection systems, ensuring the output light achieves a target white balance by calculating and adjusting drive current values for each primary color based on measured optical properties, synchronized with the color sequence timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If SSL sources replace UHP lamps in projection systems, then environmental friendliness and energy efficiency are improved, but white balance and color balance deteriorate due to different luminous flux ratios
Solution Approach 1:
The patent applies dynamics by modulating the drive current of SSL sources in real-time according to the rotating color wheel position. The drive current is dynamically adjusted to compensate for the different luminous flux ratios of SSL sources compared to UHP lamps, thereby maintaining proper white balance while preserving the energy efficiency benefits of SSL technology.
Solution Approach 2:
The patent changes the drive current parameter of the SSL sources based on the color wheel rotation and measured color properties. By adjusting the drive current values for different color segments, the system compensates for the inherent differences in luminous flux ratios between SSL sources and traditional UHP lamps, restoring accurate white balance.
2Duration of action of stationary object
If SSL sources are used in projection systems, then device lifetime is improved, but white balance varies due to aging and temperature changes
Solution Approach 1:
The patent implements feedback by using a detector to measure the actual color properties of the light output and comparing it with target values. The system then adjusts the SSL source drive currents based on this feedback to compensate for white balance variations caused by aging and temperature changes, maintaining stable color output over the extended device lifetime.
Solution Approach 2:
The system performs self-adjustment by automatically detecting color deviations and correcting them through drive current modulation without requiring manual intervention. This self-service capability ensures long-term white balance stability as the system adapts to gradual changes from aging and temperature variations.
3Object-generated harmful factors
If SSL sources replace traditional lamps, then environmental pollution is reduced, but luminance and color output differ from original specifications
Solution Approach 1:
The patent uses dynamic modulation of SSL source drive currents synchronized with the color wheel rotation to adjust luminance output. By varying the drive current in real-time, the system compensates for differences in luminous flux between SSL sources and traditional lamps, maintaining desired luminance levels while preserving environmental benefits.
Solution Approach 2:
The system changes the drive current parameters of SSL sources to match the luminance and color output characteristics of traditional UHP lamps. This parameter adjustment allows SSL sources to reproduce the original luminance and color specifications while maintaining their environmental advantages.
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 allows for precise adjustment of white balance and luminance in SSL-based projection systems, maintaining desired color output while adapting existing equipment, reducing environmental impact, and accommodating user preferences without altering the projector's hardware or software.
Implementation Method 1
solid state light (SSL) sources based on laser diodes (LDs) or light emitting diodes (LEDs)
Implementation Method 2
a blue or ultraviolet (UV) light emitting device to excite a wavelength conversion material such as phosphors
Data Source
AI summary
A white balance adjustment method and apparatus for a single DLP projector system is disclosed. The projection system includes a solid state light source device, a sync signal generator, and a controller. The light source device generates an output which is a repeating color sequence of at least two primary color lights. The sync signal generator generates a synchronization signal representing a timing of the color sequence of the output light. The controller calculates drive current values corresponding to each of the two primary colors based on a target white balance and measured color properties of the output light, and supplies a modulated drive current to the light source device. The modulated drive current is synchronized to the sync signal and has the calculated drive current values. As a result, a white light having the target white balance is output.