In-Car Display Optical Sheet Fixing via Rubber Cushion Segmentation
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Solution Overview
Problem
In-car display devices face issues with damage to optical sheets and light guide plates due to vibration and temperature changes, leading to wrinkles, backlash, and reduced display quality, as existing technologies fail to adequately address the thermal expansion and mechanical stress on resin materials.
Innovation Solution
A display device configuration featuring a box-shaped frame with L-shaped locking members and rubber cushion members that distribute stress and absorb thermal expansion, incorporating cut-out recesses in the optical sheets to fit the protrusions, preventing positional shifts and damage by distributing load and minimizing clearance for temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the light guide plate is pressed onto the side wall surfaces of the metal frame by spring elasticity of the protrusions, then the light guide plate is fixed, but the light guide plate is chipped off because of rubbing between the end portion of the metal frame and the light guide plate due to vibration
Solution Approach 1:
A rubber cushion member is introduced as an intermediary between the metal frame and the light guide plate. This rubber member absorbs vibration energy and prevents direct contact rubbing between the metal frame end portion and the light guide plate, thereby preventing chips while maintaining fixing reliability through elastic deformation.
2Reliability
If the light guide plate is pressed onto the side wall surfaces of the metal frame by spring elasticity of the protrusions, then the light guide plate is fixed, but the light guide plate has a large amount of expansion particularly under high temperature and a large force is applied to the protrusions of the metal frame, thereby causing deformation of the light guide plate
Solution Approach 1:
The rubber cushion member serves as a thermal buffer between the metal frame and the light guide plate. Its elastic properties allow it to accommodate thermal expansion differences, reducing the force transmitted to the light guide plate during high temperature conditions and preventing deformation.
3Reliability
If the optical sheets are fixed by being sandwiched between the light guide plate and the frame, then the optical sheets are held in position, but damage and wrinkles occur in the extended portion because only the extended portion protrudes from the short side of the optical sheet and the force applied is concentrated there
Solution Approach 1:
The fixing structure is segmented into multiple rubber cushion members distributed at different positions (corner portions and intermediate portions) along the side walls. This segmentation distributes the fixing force across multiple points rather than concentrating it at the extended portion, preventing damage and wrinkles while maintaining positional stability.
4Temperature
If a clearance corresponding to amounts of expansion and contraction due to temperature change is formed in advance, then temperature expansion is accommodated, but backlash, damage, and looseness occur because the clearance is large
Solution Approach 1:
The rubber cushion member's elastic modulus and hardness are selected to provide appropriate elasticity that allows thermal expansion accommodation through controlled elastic deformation. This elasticity enables the system to absorb expansion/contraction movements without requiring large clearances, thereby preventing backlash and looseness while still accommodating temperature changes.
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 effectively prevents damage to optical sheets and light guide plates, maintaining display quality under varying temperatures and intense vibrations by distributing stress and minimizing positional shifts and thermal expansion effects.
Implementation Method 1
rubber cushion members 2 are arranged between a light guide plate 1 and side walls of a lower frame 3 to alleviate movement of the light guide plate 1 due to vibration by the rubber cushion members 2
Implementation Method 2
the light guide plate is pressed onto the side wall surfaces of the metal frame by spring elasticity of the protrusions, thereby holding the light guide plate
Implementation Method 3
when compared to the metal frame, the light guide plate made of a resin material has a larger coefficient of thermal expansion, and hence there is also a problem in that the light guide plate has a large amount of expansion particularly under high temperature
Data Source
AI summary
Provided is a display device, including: a first protrusion formed to an inner side surface of one of side walls of the frame on a short side of an angled corner portion surrounded by the side walls; a second protrusion formed to an inner side surface of one of the side walls on a long side of the angled corner portion; and a third protrusion formed at another angled corner portion on another end side of at least one of the side walls sharing the angled corner portion provided with the first and second protrusions, and formed to an inner side surface of one of the side walls that is opposed to the side wall to which the first protrusion and/or the second protrusion are/is arranged, the optical sheet including cut-out first to third recesses which are to be fitted to the first to third protrusions.