Aspheric Mirror Projection System for Thin Enclosure Depth
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Solution Overview
Problem
Conventional micromirror-based projection display systems have larger 'chin' and 'depth' dimensions compared to LCD and plasma displays, making them less competitive due to the need for larger enclosures to accommodate light sources and projection optics, and they suffer from distortion and instability due to thermal and alignment issues.
Innovation Solution
A micromirror-based projection display system utilizing a laser light source, telecentric projection lenses, and a medium-to-wide angle aspheric mirror formed of plastic, which reduces the physical dimensions of the enclosure while maintaining high resolution and stability by compensating for aberrations and environmental variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional micromirror-based projection systems use traditional optical engines with light sources and projection optics, then image brightness and clarity are improved, but the chin and depth dimensions of the enclosure increase
Solution Approach 1:
The patent transitions from a traditional linear optical path to a folded optical path that utilizes multiple dimensions (front-to-back and side-to-side) to achieve the same projection function. The light source is positioned at an angle to the display screen, and optical elements are arranged in a folded configuration that projects light from the front face of the enclosure rather than from the rear, thereby reducing the required depth while maintaining brightness.
2Length of stationary object
If the light source is positioned closer to the display screen to reduce depth, then enclosure depth is reduced, but the angle of incidence becomes too shallow causing flare and reduced contrast
Solution Approach 1:
The patent employs asymmetric positioning of the light source relative to the display screen, placing it at an angled position rather than symmetrically behind the screen. This asymmetric arrangement allows the optical system to achieve the necessary incident angles for high-quality image projection while maintaining a compact depth profile, as the light path is optimized for the specific geometric relationship between the angled light source and screen.
3Measurement precision
If traditional projection optics are used to maintain image quality, then resolution and clarity are preserved, but the system becomes more sensitive to thermal and alignment variations
Solution Approach 1:
The patent modifies key optical parameters including the numerical aperture, focal length, and incident angle of the projection optics to create a system that is inherently less sensitive to thermal expansion and alignment variations. By optimizing these parameters within specific ranges, the system maintains high resolution while achieving improved stability and reduced sensitivity to environmental changes compared to conventional designs.
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 system achieves minimal 'chin' and 'depth' dimensions, high resolution, and improved stability against temperature and humidity changes, making it competitive with LCD and plasma displays in terms of form factor and image quality.
Implementation Method 1
a medium-to-wide angle aspheric mirror formed of plastic, which reduces the physical dimensions of the enclosure while maintaining high resolution and stability
Implementation Method 2
telecentric projection lenses
Data Source
AI summary
A micro-mirror based projection display system in an enclosure with minimum chin and depth measurements is disclosed. A solid-state laser light source generates light of multiple primary colors that is modulated by a digital micro-mirror device. The projection optics of the system include a telecentric rear group of glass lenses with spherical surfaces, followed by a pair of aspheric lenses formed of plastic. A folding mirror is disposed between the aspheric lenses, to reduce the depth of the enclosure, and an aspheric mirror projects the image onto a TIR Fresnel projection screen. The aspheric lenses are magnifying, to reduce the magnification required of the aspheric mirror, and the aspheric lenses and mirror are clipped to reduce enclosure volume.