Planar Illumination Device Fixing Member for LED Alignment
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Solution Overview
Problem
Conventional planar illumination devices face challenges in maintaining accurate mounting of LEDs on substrates due to self-alignment issues caused by solder melting, leading to decreased brightness characteristics, especially as devices become thinner and more compact.
Innovation Solution
A planar illumination device design that incorporates a fixing member cured at a temperature lower than the solder's melting point to maintain the position and posture of the LED, preventing self-alignment and ensuring high accuracy in mounting, even with poorly balanced LED shapes and varying aspect ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If self-alignment technique is used to correct misalignment of LED, then LED posture can be adjusted, but mounting accuracy deteriorates due to solder melting
Solution Approach 1:
The patent applies preliminary action by curing the fixing member before the solder melts during reflow soldering. The fixing member is cured at a temperature lower than the solder melting point, which prevents LED displacement while allowing the solder to properly bond the LED to the substrate. This sequence of operations ensures both alignment correction and mounting accuracy are achieved.
2Volume of moving object
If light guide plate is made thinner to narrow frame, then device compactness improves, but LED mounting accuracy becomes more difficult to maintain
Solution Approach 1:
The fixing member is cured before soldering to preliminarily secure the LED in the correct position. This preliminary fixation prevents LED displacement even when the light guide plate is thin, ensuring mounting accuracy is maintained despite the reduced margin for error in thinner device configurations.
Solution Approach 2:
The patent changes the temperature parameter by using a fixing member that cures at a temperature lower than the solder melting point. This parameter change allows the fixing member to set the LED position before thermal processing, preventing accuracy degradation in thin-device configurations where traditional post-solder alignment would fail.
3Manufacturing precision
If fixing member is cured at temperature lower than solder melting point, then LED position is maintained, but solder bonding may be affected
Solution Approach 1:
The fixing member is cured in advance before the soldering process to preliminarily secure the LED position. This preliminary action ensures the LED remains stationary during subsequent soldering, and the solder bonding proceeds normally without interference from LED displacement, thus maintaining both position accuracy and bonding reliability.
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 enables high-accuracy LED mounting and improved brightness characteristics while accommodating the demand for reduced thickness in planar illumination devices, stabilizing light coupling efficiency and preventing damage from external forces.
Implementation Method 1
a fixing member that is cured at temperature lower than a melting point of the solder and fixes the light source to the substrate while maintaining a position and a posture of the light source
Implementation Method 2
a substrate on which the light source is mounted by bonding a bonding surface of the light source thereto by a solder
Data Source
AI summary
A planar illumination device according to an embodiment includes a light guide plate, a light source, a substrate, and a fixing member. The light guide plate causes light incident on a side surface to exit from a light exit surface. The light source is arranged on a side of the side surface of the light guide plate and has a light emitting surface to emit light toward the side surface. The light source is mounted on the substrate by bonding a bonding surface of the light source thereto by a solder. The fixing member is cured at temperature lower than a melting point of the solder and fixes the light source to the substrate while maintaining a position and a posture of the light source.