Heads-Up Display Reflective Film for Sunlight Backflow Filtering

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Solution Overview

Problem

The backflow of external interference light, such as sunlight, affects the operating performance and service life of image generating devices in heads up display systems by causing temperature rise and potential damage.

Innovation Solution

Incorporating a wavelength-selective reflective film on the reflective assembly of the heads up display system to reflect and filter out interference light with wavelengths outside the image light band, thereby reducing the impact on the image generating device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a reflective assembly is used to project image light, then image projection is achieved, but external interference light backflows into the image generating device causing temperature rise

Engineering Contradiction:

Improveimage projectionVSAvoidimage generating device temperature

Core Design Contradiction:

Illumination intensityVSTemperature

Solution Approach 1:

A wavelength-selective reflective film is introduced as an intermediary component on the reflective assembly. This film selectively reflects image light wavelengths while absorbing or blocking external interference light wavelengths, thereby mediating between the need for image projection and the need to prevent temperature rise from backflowing light

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The reflective assembly is modified by adding a wavelength-selective reflective film that changes the spectral parameters of reflected light. The film is configured to reflect specific wavelength ranges (image light) while absorbing or blocking other wavelength ranges (external interference light), thereby controlling which light reaches the image generating device

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If a reflective assembly is used to project image light, then image projection is achieved, but service life of the image generating device is reduced due to light backflow

Engineering Contradiction:

Improveimage projectionVSAvoidservice life

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The wavelength-selective reflective film serves as a protective intermediary that filters harmful external light before it reaches the image generating device, thereby preserving the device's service life while maintaining image projection functionality

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The solution converts the potentially harmful backflow of external interference light into a beneficial filtering mechanism. The wavelength-selective reflective film uses its selective reflection and absorption properties to block harmful wavelengths while allowing useful image light to pass, effectively turning a problem into a solution

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 filters out external interference light, preventing temperature rise and improving the service life and imaging quality of the image generating device while ensuring normal image projection.

Implementation Method 1

The reflective assembly is configured to reflect image light emitted by the image generating device to a projection surface

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

a wavelength-selective reflective film located on a reflective surface of the reflective assembly. The wavelength-selective reflective film is configured to reflect at least part of the image light

Methodology Applied

Scientific EffectWavelength-selective reflection: Dichroic Filter

Implementation Method 3

The wavelength-selective reflective film is configured to reflect at least part of the image light... effectively filters out external interference light, preventing temperature rise

Methodology Applied

Scientific EffectSelective absorption: Absorption (EM radiation)

Data Source

PatentUS20260016693A1Heads up display system and vehicle

Publication Date: 2026.01.15 XIAMEN TIANMA MICRO ELECTRONICS

AI summary

Provided are a heads up display system and a vehicle. An image generating device emits image light, which is reflected to a projection surface through a reflective assembly; a wavelength-selective reflective film is located on a reflective surface of the reflective assembly, realizing the selective reflection for different wavelength bands. The wavelength-selective reflective film is configured for reflecting at least part of the image light, ensuring that the image light is not affected by the arrangement of the wavelength-selective reflective film. When external interference light enters the heads up display system along a reverse optical path of the image light, the external interference light will first enter the wavelength-selective reflective film before entering the image generating device. The wavelength-selective reflective film only reflects interference light with the same wavelength band as the image light, thereby preventing the most of the interference light from entering the image generating device.