Projection Display With Blue-Laser Wavelength Diversity for Fringe Reduction
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Solution Overview
Problem
Conventional projection display devices using reflective liquid crystal display elements experience temperature non-uniformity at startup, leading to the generation of fringes (interference fringes) due to uneven thickness, which are superposed on the displayed image.
Innovation Solution
A projection display device equipped with a light source comprising a group of blue lasers with different oscillation wavelengths, a heating unit on the back surface of the blue liquid crystal display element, and temperature sensors to control heating, ensuring uniform temperature distribution and reducing fringe generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single wavelength blue laser is used as a light source, then the device structure is simplified, but fringes (interference fringes) are generated due to non-uniform temperature distribution in the liquid crystal display element
Solution Approach 1:
The patent uses multiple blue laser light sources with different oscillation wavelengths to change the optical parameter (wavelength) of the light source. This parameter change causes interference fringes of different wavelengths to overlap and cancel each other out, thereby reducing the visibility of fringes on the displayed image while maintaining a relatively simple device structure.
2Object-affected harmful factors
If the liquid crystal display element is heated to operational temperature, then fringe generation is reduced, but additional heating components and control systems are required
Solution Approach 1:
Instead of changing the temperature parameter to eliminate fringes, the patent changes the wavelength parameter of the light source. By using multiple blue lasers with different wavelengths, the system eliminates fringe visibility issues without requiring additional heating components or temperature control systems, thus avoiding increased device complexity.
3Object-affected harmful factors
If multiple blue lasers with different oscillation wavelengths are used, then fringe generation is reduced, but the light source structure becomes more complex
Solution Approach 1:
The patent employs multiple blue laser light sources with different oscillation wavelengths, changing the wavelength parameter to reduce fringe generation. While this does increase light source structure complexity, the increase is minimal compared to alternative approaches such as adding heating systems, and it effectively solves the fringe problem.
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 effectively minimizes fringe generation by uniformly heating the liquid crystal display elements to operational temperatures, allowing for stable image projection with reduced interference fringes.
Implementation Method 1
a heating unit arranged, via a heat sink, on at least a back surface of the liquid crystal display element corresponding to blue
Data Source
AI summary
A projection display device that enables adequate reduction of generation of fringes is to be provided. A projection display device according to an embodiment includes: a light source that emits light in a blue wavelength range; a first display element, a second display element, and a third display element that are respectively arranged correspondingly to red, green, and blue and generate image light corresponding to each color; a heater arranged, via a heat sink, on at least a back surface of the third display element corresponding to blue; and a temperature sensor provided on the heat sink; the light source has a group of plural blue laser light sources having different oscillation wavelengths; and the projection display device includes a heater control unit that causes the heater to operate in a case where a temperature detected by the temperature sensor is lower than a predetermined first temperature.