LED Illumination Unit with Recessed Light Guide Plate
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Solution Overview
Problem
Conventional illumination units using LEDs as backlights for display devices suffer from uneven brightness due to localized light intensity increases near the light source and dark areas between LEDs, which are not adequately addressed by existing light shielding or reflective/absorbing members.
Innovation Solution
The solution involves a tabular light guide plate with recessed portions for LED placement, where the optical axis is parallel to the light emitting surface, and a dimming pattern with elliptic and radial protrusions on the light emitting surface to reduce uneven brightness by controlling light emission and reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light shielding member or light reflective/absorbing member is provided in the vicinity of the light source of the light guide plate, then the uneven brightness near the light source is reduced, but the dark portion between LEDs is not sufficiently addressed
Solution Approach 1:
The invention applies local quality by creating a recessed portion specifically at the light incident portion of the light guide plate, and providing a light shielding member only in the vicinity of the light source. This localized structural modification targets the specific area causing uneven brightness without complicating the entire device structure, thereby reducing brightness non-uniformity while maintaining manufacturing simplicity.
2Illumination intensity
If conventional light shielding members are used, then some uneven brightness is reduced, but the configuration does not take into consideration the radial light emission characteristic of LEDs
Solution Approach 1:
The invention changes the geometric parameters of the light guide plate by introducing a recessed portion at the light incident area. This structural parameter change modifies how light enters and distributes within the plate, enabling better control over light propagation paths and improving the precision of light distribution to match the radial emission characteristics of LEDs.
3Area of stationary object
If multiple LEDs are arranged in a predetermined direction, then the overall illumination coverage is improved, but dark portions appear between the LEDs
Solution Approach 1:
The invention addresses the one-dimensional arrangement problem of LEDs by introducing a vertical dimension through the recessed portion structure. This dimensional change allows light to be introduced from below at specific locations, filling in the dark portions between laterally arranged LEDs and achieving more uniform two-dimensional illumination coverage.
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 optical spots and uneven brightness, ensuring a more uniform light distribution and improved image quality in display devices.
Implementation Method 1
the light incoming from the light source travels inside the light guide plate by total internal reflection or the like
Implementation Method 2
is scattered by a diffusion/light-guide pattern provided on the surface of the light guide plate, and is extracted from the surface of the light guide plate
Data Source
AI summary
An illumination unit of the present invention includes a tabular light guide plate having a light emitting surface for emitting light coming from an LED as planar light, wherein a recessed portion is formed in the opposite surface of the light emitting surface of the light guide plate, and wherein the LED is provided in the recessed portion so that the optical axis of the LED becomes parallel to the light emitting surface of the light guide plate. Then, a dimming pattern is provided at a location corresponding to the LED of the light emitting surface of the light guide plate, and the dimming pattern includes a main portion covering the LED on the light emitting surface side, and protrusions radially extending toward a light emitting direction of the LED around the LED.