Side-view LED Package with Concave Cavity and Spacer
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Solution Overview
Problem
Side-view type light emitting devices face challenges in maintaining uniform light irradiation on light guide panels due to the point light source nature of LEDs, positional variations during the reflow soldering process, and thermal expansion, which affects light uniformity and alignment with the backlight unit.
Innovation Solution
A side-view type light emitting device with a package body featuring a concave portion, lead frames, a resin covering portion, and spacer portions to maintain a constant distance from the light irradiation target, ensuring uniform light distribution and preventing thermal expansion-induced changes in light input rate without reducing the view angle of emitted light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the light guide panel is expanded by heat generated during LED operation, then thermal energy increases, but the distance between LED and light guide panel changes or they are closely adhered, causing non-uniform light irradiation
Solution Approach 1:
The spacer portion is formed in advance on the package body at a position corresponding to the light emitting surface, creating a pre-established mechanical structure that maintains a predetermined distance between the LED and light guide panel before thermal expansion occurs during operation
Solution Approach 2:
The spacer portion acts as an intermediary mechanical element positioned between the LED package body and the light guide panel, preventing direct thermal contact and maintaining a constant gap that accommodates thermal expansion while preserving uniform light irradiation
2Use of energy by moving object
If an LED light source is used instead of CCFL, then energy efficiency improves, but light uniformity deteriorates because LED is a point light source
Solution Approach 1:
The concave portion is formed locally at a specific position on the package body to concentrate and redirect light emission toward the light guide panel, creating a localized optical enhancement that improves uniformity without sacrificing the energy efficiency of the LED source
Solution Approach 2:
The concave portion modifies the light emission pattern by creating a three-dimensional optical structure that redirects light in multiple directions, effectively transforming the point source characteristics into a more distributed illumination pattern across the light guide panel
3Area of stationary object
If the number of LEDs is increased to cover larger BLU area, then light coverage improves, but positional accuracy deteriorates due to reflow soldering tolerance
Solution Approach 1:
The spacer portion is pre-formed on the package body during manufacturing, establishing a fixed reference structure that determines the final positioning of the LED assembly relative to the light guide panel, thereby compensating for variations introduced during the reflow soldering process
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 ensures consistent and uniform light irradiation on light guide panels across various positions and driving times, maintaining high light input efficiency and preventing rapid changes in light input rate due to thermal expansion, while preserving the view angle of emitted light.
Implementation Method 1
a light emitting diode chip mounted on the bottom of the concave portion to be electrically connected to each of the first and second lead frames
Implementation Method 2
a light emitting diode (LED) is provided as a light emitting device
Implementation Method 3
a resin covering portion formed in the concave portion to enclose the light emitting diode chip
Implementation Method 4
when the light guide panel is expanded by the heat generated during the operation of an LED, the distance between the LED and the light guide panel changes or they are closely adhered to each other
Data Source
AI summary
A side-view type light emitting device includes a package body, first and second lead frames, a light emitting diode chip, a resin covering portion, and at least one spacer portion. The package body has a first surface provided as a mounting surface, a second surface located opposite to the first surface, side surfaces located between the first surface and the second surface, and a concave portion formed at one of the side surfaces corresponding to the light emitting surface.