Hybrid Light Source Filtering for Same-Color Projection Beam Mixing

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Solution Overview

Problem

Existing light combining methods, such as using dichroic mirrors and light combining elements, struggle to effectively mix light beams of the same color due to limitations in achieving both transmission and reflection for light beams with similar wavelengths.

Innovation Solution

A hybrid light source system comprising a first and second light source group emitting light beams of the same color but different wavelengths, with a bandpass filter arranged at a 45-degree angle to each light source group, reflecting one and transmitting the other, and a light combining element to combine these beams, allowing for precise wavelength selection and mixing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If dichroic mirrors or light combining elements are used to combine light beams, then light beams of different colors can be combined, but light beams of the same color cannot be effectively mixed

Engineering Contradiction:
Improvelight beam combination capabilityVSAvoidsame color light mixing difficulty
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by using a bandpass filter with specifically designed wavelength characteristics to differentiate between same-color light beams. Instead of relying on color differences, the system changes the wavelength parameter selection to enable discrimination and combination of same-color beams with different wavelength ranges, thereby resolving the limitation of conventional light combining methods

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces a bandpass filter as an intermediary element between the light sources and the combining optics. This intermediary component selectively transmits specific wavelength ranges while blocking others, enabling the system to distinguish and properly combine same-color light beams that would otherwise be indistinguishable to conventional dichroic mirrors

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If a bandpass filter with narrow bandwidth is used to reflect one light beam and transmit another, then precise wavelength control is achieved, but device complexity increases

Engineering Contradiction:
Improvewavelength selection precisionVSAvoidoptical system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The bandpass filter performs multiple functions simultaneously: it acts as a wavelength selector, a beam separator, and a combination enabler. By making this single component multi-functional, the patent achieves precise wavelength control without proportionally increasing overall device complexity, as the filter replaces what would otherwise require multiple separate optical elements

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 enables effective mixing of light beams of the same color, improving brightness and reducing speckle issues, enhancing display quality in projection devices by utilizing a bandpass filter with narrow bandwidth for precise wavelength control.

Implementation Method 1

the bandpass filter is configured to reflect the light beam of the first light source group and transmit the light beam of the second light source group

Methodology Applied
Scientific EffectBandpass filter wavelength selection: Filter (optical)

Implementation Method 2

an angle of 45 degrees is formed between the emergent direction of the light beam of the first light source group and the bandpass filter

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP3958058B1Mixed light source system and projection display device
Publication Date: 2025.09.03 CHENGDU XGIMI TECH CO LTD
  • EP3958058B1 patent drawingFigure 1
  • EP3958058B1 patent drawingFigure 2
  • EP3958058B1 patent drawingFigure 3

AI summary

The present invention provides a hybrid light source system, the hybrid light source system includes a first light source group, a second light source group, and a bandpass filter. The first light source group and the second light source group emit light beams which are the same in color and different in wavelength range. An emergent direction of a light beam of the first light source group and an emergent direction of a light beam of the second light source group are perpendicular to each other. The bandpass filter is arranged on emergent light paths of the first light source group and the second light source group, an angle of 45 degrees is formed between the emergent direction of the light beam of the first light source group and the bandpass filter, an angle of 45 degrees is formed between the emergent direction of the light beam of the second light source group and the bandpass filter, the bandpass filter is configured to reflect the light beam of the first light source group and transmit the light beam of the second light source group. The bandpass filter with a narrower bandwidth to a transitional wavelength range is used in the present invention to combine two light beams of wavelength ranges very close to each other, thereby meeting requirements on light filling for the light beams of the same color, providing various hybrid light sources required for illumination of projection display devices, and improving display effects of the projection display devices. The present invention further provides a projection display device having the above advantages.