Multi-Layer Light Guide Plates for Uniform Display Illumination
Solution Overview
Problem
Conventional lighting devices for display devices using multiple light emitting elements suffer from luminance unevenness and require a large number of elements due to the need for thick diffuser plates or light mixing chambers, leading to increased manufacturing costs and size, especially when producing white light from red, green, and blue components without significant light loss through color filters.
Innovation Solution
A lighting device comprising multiple layers of light-transmitting guide plates with reflecting surfaces on their backside, allowing light fluxes from red, green, and blue light emitting elements to be directed and combined efficiently without color filters, reducing the need for thick diffuser plates and minimizing light loss, thereby reducing the number of light emitting elements required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple light emitting elements are arranged apart from each other to oppose the diffuser plate or light guide plate, then positioning is facilitated, but luminance unevenness increases in proportion to the interval between the diffuser plate and light emitting elements
Solution Approach 1:
The patent transitions from a single-plane arrangement of light emitting elements to a three-dimensional stacked configuration with multiple layers. By arranging light emitting elements in multiple layers at different positions and orientations, the system achieves both ease of positioning (through standardized layer structures) and improved luminance uniformity (through multi-directional light distribution that eliminates the direct proportionality between interval and unevenness).
2Illumination intensity
If a thick diffuser plate or light mixing chamber is used to mix red, green, and blue light, then color mixing is improved, but device size and manufacturing cost increase
Solution Approach 1:
The patent combines multiple light emitting elements emitting different colors (red, green, blue) within the same layered structure, allowing them to share common support substrates and packaging. This merging approach enables effective color mixing without requiring a separate thick diffuser plate or light mixing chamber, thereby reducing overall device size while maintaining color mixing quality.
Solution Approach 2:
The patent employs a nested layered structure where light emitting elements are arranged in multiple layers at different heights and positions. The lower layers are nested within the vertical space occupied by upper layers, creating a compact three-dimensional configuration. This nesting enables sufficient light path length for color mixing without increasing the horizontal footprint or requiring additional thick diffusing components.
3Productivity
If the number of light emitting elements is reduced to improve manufacturing facility and save cost, then productivity increases, but luminance unevenness becomes more remarkable
Solution Approach 1:
The patent segments the lighting system into multiple independent layers, each containing a reduced number of light emitting elements. Rather than requiring one large array of elements in a single plane, the system divides the total element count across multiple layers. This segmentation allows each layer to have fewer elements (improving manufacturing efficiency per layer) while the combined effect of all layers maintains luminance uniformity through distributed light emission from multiple z-positions.
4Illumination intensity
If color filters are used to produce white light from red, green, and blue components, then color accuracy is improved, but significant light loss occurs
Solution Approach 1:
The patent extracts and eliminates the color filter component from the optical system. Instead of using color filters to select and combine red, green, and blue wavelengths (which absorbs and loses significant light), the system directly emits these wavelengths from dedicated light emitting elements and combines them additively. This extraction of the filtering step removes the inherent light loss mechanism while maintaining color accuracy through direct spectral emission from the LED elements.
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 solution achieves improved luminance uniformity and reduced manufacturing costs by minimizing the number of light emitting elements needed, while also allowing for a more compact design and efficient light utilization, resulting in a display device with high luminance and appropriate color reproduction without the need for color filters.
Implementation Method 1
each of the light-transmitting guide plates is provided, on a backside thereof with a plurality of reflecting surfaces that change a propagation direction of the light flux propagated in the each light-transmitting guide plate to thereby emit the light flux from a front side of the each light-transmitting guide plate
Data Source
AI summary
A lighting device includes a plurality of light-transmitting guide plates 1, 2, 3 laminated in at least three layers and a plurality of light emitting elements 4, 5, 6 arranged so as to oppose to respective lateral sides of the light-transmitting guide plates 1, 2, 3 to allow luminance flux in different color with respect to each light-transmitting guide plate to be incident on the corresponding light-transmitting guide plate. Each of the light-transmitting guide plates 1, 2, 3 has a plurality of reflecting surfaces 7, 8, 9 formed on the backside of the plate to change a propagation direction of the luminance flux propagated in the each light-transmitting guide plate, allowing the luminance flux, of which propagation direction has been changed by the reflecting surfaces 7, 8, 9, to be emitted from the front side of the each light-transmitting guide plates.