Projector Mirror Array Speckle Reduction via Tilt Angle Switching
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Solution Overview
Problem
Projectors using laser light sources face the challenge of speckle, a deterioration in image quality due to laser coherence, which existing methods attempt to address by adding new units that increase the size and cost of the projector.
Innovation Solution
A projector design that includes a light source, a mirror array device, and a tilt angle controller, where the tilt angle of mirrors is switched between reference and non-reference angles based on an image signal to deflect illumination light, reducing speckle without increasing configuration size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser light source is used for illumination, then brightness and coherence are improved, but speckle is generated causing image quality deterioration
Solution Approach 1:
The patent applies periodic action by switching the tilt angle of mirrors in the mirror array device at regular intervals (e.g., alternating between odd and even frames). This periodic variation in light reflection paths causes the speckle pattern to change over time, and the human eye's temporal integration averages these variations, effectively reducing speckle visibility while maintaining laser brightness
Solution Approach 2:
The patent implements dynamics by making the mirror tilt angles variable rather than fixed. The tilt angle controller dynamically adjusts mirror angles based on frame timing (odd/even frames), creating multiple light reflection paths that shift the speckle pattern. This dynamic adjustment transforms the static speckle pattern into a time-varying one that averages out to reduced speckle
2Object-affected harmful factors
If speckle reduction mechanisms are added to the projector, then speckle is reduced, but device size and configuration complexity increase
Solution Approach 1:
The patent applies universality by making the mirror array device perform dual functions: (1) spatial light modulation for image generation, and (2) temporal speckle reduction through tilt angle switching. The same mirror array structure that creates the projection image also reduces speckle when its tilt angles are periodically varied, eliminating the need for separate speckle reduction components
Solution Approach 2:
The patent implements self-service by enabling the mirror array device to reduce speckle using its own structural properties without external assistance. The tilt angle controller, integrated with the mirror array, autonomously switches between different tilt angles to generate speckle reduction effect, making the system self-sufficient for both image generation and speckle mitigation
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 effectively reduces speckle by temporally varying the light intensity distribution, achieving the speckle reduction effect through time averaging without the need for additional speckle reduction mechanisms, thus minimizing size and cost increments.
Implementation Method 1
The mirror array device includes a plurality of mirrors, and varies a tilt angle of each of the mirrors on the basis of an image signal to deflect the illumination light toward the projection optical system
Implementation Method 2
The tilt angle controller performs switching control, on the basis of the image signal within a predetermined period, on the tilt angle of each of the mirrors in a case of deflecting the entering light toward the projection optical system. The switching control is control of switching the tilt angle between a reference tilt angle and one or a plurality of non-reference tilt angles different from the reference tilt angle
Data Source
AI summary
A projector of the present disclosure includes a light source section, a projection optical system, a mirror array, and a tilt angle controller. The light source section emits light as source of illumination light. The projection optical system projects an image onto a projection surface using the illumination light. The mirror array device includes a plurality of mirrors. The mirror array varies a tilt angle of each of the mirrors to deflect the illumination light toward the projection optical system, and generates the image from the illumination light. The tilt angle controller performs switching control on the tilt angle of each of the mirrors in a case of deflecting the entering light toward the projection optical system. The switching control is control of switching the tilt angle between a reference tilt angle and one or a plurality of non-reference tilt angles different from the reference tilt angle.