Rotary Mirror Light Source Unit for Compact Projector Speckle Reduction

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Solution Overview

Problem

Conventional projectors using semiconductor light emitting devices face challenges in reducing speckle noise and size, as existing solutions often require larger light diffusing devices that increase the overall size of the light source unit and projector.

Innovation Solution

A light source unit incorporating a rotary mirror device with a mirror surface featuring an undulating section shape of convex and concave portions, which reflects light emitted from semiconductor light emitting devices to reduce speckle noise and minimize the size of the light source unit, while a projector control unit manages the light source and display devices to project clear images.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a disc-shaped light diffusing device is driven to rotate with the rotational shaft connected to the center, then speckle noise is reduced, but the light diffusing device must be enlarged in size to pass laser beams through the radially outer side

Engineering Contradiction:

Improvespeckle noiseVSAvoidlight diffusing device size

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

Instead of connecting the rotational shaft to the center and passing beams through the outer side, this patent inverts the approach by connecting the rotational shaft to the outer peripheral portion and passing laser beams through the central portion. This inversion allows the use of a smaller light diffusing device while still achieving speckle noise reduction through rotation.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the spatial arrangement by positioning the rotational shaft at the outer periphery rather than the center, effectively utilizing the outer dimensional space for the shaft connection while keeping the beam path through the compact central region. This dimensional reconfiguration enables compact device size without sacrificing noise reduction functionality.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If a disc-shaped light diffusing device is used to reduce speckle noise, then speckle noise is reduced, but the light source unit and projector are enlarged in size

Engineering Contradiction:

Improvespeckle noiseVSAvoidprojector size

Core Design Contradiction:

Object-affected harmful factorsVSVolume of stationary object

Solution Approach 1:

By inverting the conventional configuration and positioning the rotational shaft at the outer periphery rather than the center, the patent enables the light diffusing device to be compact while maintaining speckle noise reduction capability, thereby reducing the overall projector volume.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the geometric parameters of the light diffusing device by repositioning the rotational shaft to the outer peripheral portion, which allows for a more compact device design that reduces the overall projector size while preserving the noise reduction function.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If the light diffusing device is enlarged to allow laser beams to pass through the radially outer side, then speckle noise is reduced, but the device complexity and size increase

Engineering Contradiction:

Improvespeckle noiseVSAvoidlight source unit structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent simplifies the device structure by inverting the conventional configuration - placing the rotational shaft at the outer periphery and passing beams through the center. This eliminates the need for enlarged device dimensions and complex structural arrangements, achieving both speckle noise reduction and structural simplicity.

Inventive Principle:

Principle #13The other way round (Inversion)

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 noise and minimizes the size of the light source unit and projector, enabling the projection of clear images with reduced noise and compact design.

Implementation Method 1

the rotary mirror device is disposed so as to reflect light emitted from the semiconductor light emitting device on the mirror surface

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

the mirror surface has an undulating section shape of convex and concave shape portions

Methodology Applied

Scientific EffectLight scattering: Scattering

Data Source

PatentUS9983469B2Light source unit and projector having the same light source unit

Publication Date: 2018.05.29 CASIO COMPUTER CO LTD

AI summary

There is provided a light source unit including a semiconductor light emitting device, and a rotary mirror device having a mirror surface on a first side, and a second side to which a rotational shaft of a motor is connected, wherein the mirror surface has an undulating section shape of convex and concave shape portions, wherein the rotary mirror device is disposed so as to reflect light emitted from the semiconductor light emitting device on the mirror surface.