Projector Optical Path Layout for Blue Light Valve Durability
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Solution Overview
Problem
Existing projectors face challenges in preventing the deterioration of liquid crystal light valves, particularly those modulating blue light beams, when increasing light source intensity for brightness, as the blue light valve's liquid crystal is more susceptible to degradation.
Innovation Solution
A projector design incorporating a separation optical system with an extension optical system to extend the light path and a reduction optical system with a larger effective area for the first light modulation element, along with a color combining prism to combine reduced luminous flux widths of colored light beams, ensuring the first light modulation element has a larger effective area than the others, and the optical axes are parallel, thus reducing illuminance and preventing liquid crystal deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the light source intensity is increased to make the projector brighter, then the illumination intensity is improved, but the liquid crystal in the blue light modulation element deteriorates faster
Solution Approach 1:
The patent divides the optical system into separate pathways for blue light and other colors. The blue light beam is separated by the first dichroic mirror and directed through a dedicated modulation element, while other colors follow a different path. This segmentation allows independent optimization of each pathway, enabling the blue light path to have a larger effective area without affecting the overall system compactness.
Solution Approach 2:
The patent extends the light path of the blue light beam using additional optical elements (second dichroic mirror, reflecting mirrors) to create a longer, more complex pathway. This dimensional extension allows the blue light to traverse a larger effective area of the modulation element while maintaining the same physical footprint of the projector, thereby reducing illuminance without increasing the overall device size.
2Reliability
If the effective area of the blue light modulation element is increased to reduce illuminance, then the liquid crystal deterioration is prevented, but the device complexity increases
Solution Approach 1:
The patent combines multiple optical functions into integrated components. The color separation and light path extension are achieved using dichroic mirrors that simultaneously perform wavelength separation and directional routing. The reflecting mirrors are positioned to serve multiple purposes in the optical pathway, reducing the need for separate components and simplifying the overall system architecture despite the extended light path.
Solution Approach 2:
The dichroic mirrors serve multiple functions: separating blue light from other colors, directing blue light through the extended path, and enabling the compact arrangement of optical elements. This multi-functionality reduces the total number of components needed, thereby reducing device complexity while achieving the goal of larger effective area for the blue light modulation element.
3Illumination intensity
If the light path is extended to increase the effective area, then the illuminance is reduced, but the length of the projector increases
Solution Approach 1:
The patent uses reflective optics to dynamically redirect the blue light path at multiple angles, creating a folded optical path. The light beam is reflected back and forth through the modulation element, effectively increasing the traversal distance and effective area within a compact physical space. This dynamic routing allows the system to achieve long effective light paths without proportionally increasing the projector's external dimensions.
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 design effectively prevents liquid crystal deterioration in the first light modulation element while maintaining brightness, allowing for compact projector size and maintaining color beam combination efficiency.
Implementation Method 1
a first dichroic mirror configured to separate a multicolored light beam including a first colored light beam out of outgoing light emitted from the light source into the first colored light beam in a first wavelength band including blue light and another colored light beam
Implementation Method 2
a reduction optical system having an expansion side imaging plane on which the first light modulation element is disposed, and configured to reduce a luminous flux width of the first colored light beam on a reduction side imaging plane
Implementation Method 3
a color combining prism configured to emit a composite light beam obtained by combining the first colored light beam a luminous flux width of which is reduced by the reduction optical system, and the other colored light beam modulated by the second light modulation element with each other
Data Source
AI summary
A projector includes a light source, a separation optical system including a first dichroic mirror for separating multicolored light into a first colored light beam as a blue light beam and another colored light beam, a first light modulation element for modulating the first colored light beam, a second light modulation element for modulating the other colored light beam, a reduction optical system for reducing a luminous flux width of the first colored light beam modulated by the first light modulation element, a color combining prism, and a projection optical system. The effective area of the first light modulation element is larger than the effective area of the second light modulation element. The separation optical system includes an extension optical system for extending a light path.