Projection Display Illuminance Sensor Mirror
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Solution Overview
Problem
Conventional projection-type video image display apparatuses with independent LED light sources face challenges in maintaining optimal illuminance distribution and color balance due to the need for multiple sensors, which increases costs and affects reflective characteristics, leading to uneven illuminance spots.
Innovation Solution
A projection-type video image display apparatus with independent RGB light sources, a mirror having specific transmittance characteristics, and a single illuminance sensor on the back surface to measure light quantity, allowing for precise adjustment of light emission to maintain uniform illuminance distribution and color balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors are provided for measuring light quantity of each color, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple sensing functions into a single sensor by using a color separation prism that directs different color wavelengths to different detection regions of the same sensor, thereby achieving multi-color light measurement without requiring multiple separate sensors
Solution Approach 2:
The patent introduces a color separation prism as an intermediary optical element that separates white light into its constituent colors and directs them to different measurement positions on the sensor, enabling color-specific measurement through a single sensor
2Ease of operation
If a non-reflective opening portion is provided on the prism surface for sensor mounting, then measurement function is improved, but illuminance distribution uniformity deteriorates
Solution Approach 1:
The patent applies local quality by providing reflective coating only in specific regions of the prism surface where needed for light redirection, while leaving other regions non-reflective for sensor mounting, thereby optimizing both measurement function and illuminance distribution in different locations
Solution Approach 2:
The patent segments the prism surface into different functional zones: reflective regions for light redirection and non-reflective regions for sensor mounting, allowing each zone to perform its specific function without interfering with the other
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 configuration enables accurate measurement and adjustment of light sources, ensuring uniform illuminance distribution and improved color balance without the need for multiple sensors, reducing costs and preventing unevenness in illuminance spots.
Implementation Method 1
a mirror (171) configured to reflect white light obtained by synthesizing the light rays emitted from the light sources
Implementation Method 2
making the white light pass through the mirror based on predetermined transmittance characteristics
Implementation Method 3
an illuminance sensor disposed on a back surface side of the mirror and configured to measure quantity of light of each color of the white light which has passed through the mirror
Data Source
AI summary
A projection-type video image display apparatus measures quantity of light of a plurality of light sources by maintaining illuminance distribution of an illumination luminous flux. The apparatus includes R, B and G light sources, and a mirror configured to reflect white light obtained by synthesizing the light rays emitted from the respective light sources while making the white light pass through the mirror based on predetermined transmittance characteristics. An illuminance sensor disposed on the mirror's back surface and configured to measure quantity of light for each color of the white light which passed through the mirror, and a controller adjusts an amount of light emission of the light source of each color based on the quantity of light measured. The mirror allows the transmittance characteristics of each light transmittance in the center wavelengths of the R and B lights sources to be larger than those of the G light source.