Laser Projection Speckle Reduction via Dynamic Optical Path
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Solution Overview
Problem
Current projection-type display apparatuses using semiconductor laser light sources suffer from low light emission efficiency and high coherence, resulting in speckle interference patterns that degrade image quality, with existing solutions providing insufficient speckle reduction.
Innovation Solution
A projection-type display apparatus incorporating a laser source, an integrator with rectangular lens cells, a beam irradiation position moving unit that scans the laser light across the integrator, and a modulation device to effectively reduce speckle by varying the incident angle of the laser light on the integrator's cells, thereby changing the interference pattern over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If semiconductor laser light sources are used instead of xenon lamps and ultrahigh pressure mercury lamps, then miniaturization of projection-type display apparatuses is achieved, but speckle interference patterns are produced due to high coherence, worsening image quality
Solution Approach 1:
The patent applies the dynamics principle by making the optical path length variable through a movable mirror. The mirror is driven to change its position dynamically, causing the optical path length to vary continuously. This dynamic change prevents the formation of stable speckle patterns by constantly altering the interference conditions, while still utilizing the miniaturizing advantage of laser light sources.
Solution Approach 2:
The patent applies parameter changes by varying the optical path length through mechanical movement of a mirror. The mirror's position is changed over time, which changes the optical path length parameter. This parameter variation disrupts the coherent interference that causes speckle, effectively reducing speckle interference while maintaining the compact size advantage of laser-based systems.
2Volume of moving object
If laser light sources are used, then miniaturization is achieved, but light emission efficiency is low
Solution Approach 1:
The patent applies continuity of useful action by ensuring that the laser light is continuously utilized through the movable mirror mechanism. The mirror changes position continuously, maintaining continuous optical path variation and preventing speckle formation throughout the entire operation. This continuous action ensures that the laser's coherent light is effectively utilized without creating harmful interference patterns.
3Object-affected harmful factors
If conventional solutions (prism rotation or reflection plate translation) are used to reduce speckle, then some speckle reduction effect is achieved, but the effect is insufficient
Solution Approach 1:
The patent improves upon conventional solutions by using a movable mirror that dynamically changes the optical path length. This dynamic approach is more effective than static or reciprocating mechanisms because it creates continuous, non-repeating optical path variations that more thoroughly disrupt speckle patterns, achieving superior speckle reduction effectiveness.
Solution Approach 2:
The patent enhances conventional solutions by implementing continuous optical path length variation through mirror movement. This parameter change approach is more effective than the fixed or reciprocating mechanisms in prior art, as it creates more substantial and varied optical path differences that more effectively eliminate speckle interference patterns.
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 reduces speckle interference, improving the quality of projected images by ensuring that the human eye perceives a constant image rather than the speckle pattern, thus enhancing the display's performance.
Implementation Method 1
an integrator (25) which includes a plurality of lens cells and transmits the laser beam
Implementation Method 2
cause the laser beam to scan a surface of the integrator (25) in a first direction and a second direction
Implementation Method 3
a modulation device configured to modulate the laser beam emitted from the integrator (25)
Implementation Method 4
a projection lens configured to project the laser beam modulated by the modulation device
Data Source
AI summary
An integrator includes a plurality of rectangular lens cells arranged in a direction x and a direction y. Laser light emitted from a laser source is projected onto an integrator. A beam irradiation position moving unit is configured to cause the laser light to scan the surface of the integrator in the directions x and y so that the laser light is sequentially projected onto a plurality of lens cells. A reflective liquid crystal device is configured to modulate the laser light emitted from the integrator. A projection lens is configured to project the laser light modulated by the reflective liquid crystal device.