Backlight Optical Sheet Protrusions for Luminance Uniformity
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Solution Overview
Problem
The challenge is to enhance the uniformity of luminance distribution in image display apparatuses without increasing power consumption, as existing edge light type backlight devices face issues with uneven luminance due to increased size and decreased thickness, leading to inefficiencies in light distribution.
Innovation Solution
A surface illuminating device with a light-transmissive optical sheet featuring a luminance-distribution control layer, comprising protrusions inclined in a specific direction to optimize light transmission and reflection, is used in conjunction with a diffuser plate and reflection surface to equalize luminance across the display area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the number of linear light sources is increased, then the luminance of the backlight device is improved, but the power consumption is increased
Solution Approach 1:
The patent applies local quality by introducing protrusions at specific locations on the optical sheet to locally control light distribution. These protrusions are positioned strategically to redirect light from high-luminance areas (directly above light sources) toward lower-luminance areas (between light sources), creating non-uniform light redirection that addresses local deficiencies without requiring additional light sources.
Solution Approach 2:
The protrusions act as intermediary elements between the light sources and the display panel. They mediate the light distribution by refracting and reflecting light rays, serving as an optical intermediary that redistributes light without requiring changes to the light sources themselves or adding more light-emitting components.
2Use of energy by moving object
If the distance between adjacent linear light sources is increased, then the power consumption is reduced, but the uniformity of front luminance distribution is degraded
Solution Approach 1:
The protrusions are strategically positioned to address local luminance deficiencies. By having different regions of the optical sheet with different protrusion configurations, the system creates localized light redirection that compensates for the increased spacing between light sources, ensuring uniform overall distribution without reducing the inter-source distance.
Solution Approach 2:
The patent introduces a vertical dimension (depth of protrusions) to control light distribution. By varying the height and orientation of protrusions in the Z-direction, the system adds a dimensional degree of freedom for light redirection, allowing uniform luminance distribution to be achieved even when light sources are spaced farther apart in the XY-plane.
3Length of stationary object
If the distance between linear light sources and optical sheet is decreased, then the thickness is reduced, but the uniformity of front luminance distribution is degraded
Solution Approach 1:
The protrusions create localized optical paths that compensate for the reduced distance between light sources and optical sheet. By strategically positioning protrusions to redirect light from high-luminance regions toward low-luminance regions, the system maintains uniform distribution even with the decreased spacing, eliminating the need for increased thickness.
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 effectively reduces luminance unevenness by gradually increasing light transmission as protrusions move away from the light source, maintaining inter-light-source distance while ensuring consistent luminance distribution without increased power consumption.
Implementation Method 1
a light-transmissive optical sheet including a luminance-distribution control layer formed on a light exit surface of the optical sheet
Implementation Method 2
the protrusions having ridgelines extending substantially in parallel to an extending direction of the linear light sources and being arranged continuously in an arrangement direction of the linear light sources
Implementation Method 3
The diffuser plate 4 is an optical member, in which resin is randomly contained in a transparent base, the resin having a different refractive index from a refractive index of the transparent base
Data Source
AI summary
A surface illuminating device is provided and includes a plurality of linear light sources, a light-transmissive optical sheet including a luminance-distribution control layer for decreasing unevenness in luminance of light emitted from the linear light sources, and a reflection surface for reflecting the light emitted from the linear light sources. The luminance-distribution control layer includes a plurality of protrusions. In a range of 0≦x≦L/2, protruding directions of some or all the protrusions are inclined such that the protruding directions of the protrusions are located farther from a Z direction, which is an optical axis of a linear light source in an X direction, to the X direction as the protrusions are located farther from the position of x=0 in the X direction, where the X direction represents the arrangement direction of the linear light sources.