Sign Shadow Mask Thermal Expansion Alignment
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Solution Overview
Problem
Existing sign technologies with masks to control light emission face issues with heat dissipation, leading to misalignment and parallax errors, especially in larger signs and varying weather conditions, due to the expansion of shadow masks not matching the pane's thermal expansion.
Innovation Solution
The masks and guide elements are designed with the same coefficient of thermal expansion as the pane, ensuring uniform expansion and contraction, maintaining the optical axis alignment, and are attached in a flat, compact manner for efficient heat transfer and reduced glare.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a shadow mask is arranged behind the transparent pane at a clear distance to prevent sunlight reflection and control LED light emission, then light emission precision is improved, but thermal expansion mismatch causes misalignment and parallax errors
Solution Approach 1:
The mask and guide element are made from materials with matching coefficients of thermal expansion (both approximately 9×10^-6/K), ensuring they expand and contract uniformly together. This homogeneity in thermal properties eliminates differential expansion that would cause misalignment, directly resolving the contradiction between achieving precise optical alignment and maintaining reliability under temperature variations.
Solution Approach 2:
The guide element and mask are thermally coupled through direct contact, forming a unified thermal-structural system. This merging ensures that heat from the LED propagates through the guide element to the mask, keeping both components at similar temperatures and preventing relative dimensional changes that would undermine alignment stability.
2Illumination intensity
If very bright LEDs with high heat dissipation are used to improve visibility in larger signs, then illumination intensity is improved, but the shadow mask heats up and expands causing misalignment
Solution Approach 1:
By selecting materials for the mask and guide element with matched thermal expansion coefficients, the system ensures uniform expansion behavior even under high heat loads from bright LEDs. This allows the use of high-power LEDs for improved illumination intensity without sacrificing alignment precision, as both components expand together predictably.
Solution Approach 2:
The patent specifies precise coefficient of thermal expansion values (approximately 9×10^-6/K) for the materials used in the mask and guide element. By controlling this material parameter, the system can tolerate high heat dissipation from bright LEDs while maintaining alignment, transforming the thermal challenge into a manageable design parameter.
3Manufacturing precision
If the shadow mask is dimensioned for the 'warm state' to account for thermal expansion, then alignment is improved at high temperature, but optical errors occur when the sign is cold or during initial heating
Solution Approach 1:
The mask and guide element are constructed from materials with identical thermal expansion characteristics, ensuring they maintain their relative dimensional relationship across the entire temperature range. This eliminates the need to dimension for a specific temperature state, as the system adapts uniformly whether cold, warm, or during transition, resolving the contradiction between optimized warm-state alignment and adaptability across temperatures.
4Illumination intensity
If masks are designed with larger openings to allow oblique light emission, then light distribution is improved, but glare and reflections increase
Solution Approach 1:
The mask incorporates locally varied opening patterns with different geometries and orientations in different regions. This allows optimization of light distribution in specific directions while blocking glare and reflections in others, enabling large opening areas for good light distribution without the harmful effects of uncontrolled light emission angles.
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 provides stable and precise light emission with reduced glare and optical distortions across different weather conditions, ensuring long-term durability and optical fidelity.
Implementation Method 1
The masks and guide elements are designed with the same coefficient of thermal expansion as the pane, ensuring uniform expansion and contraction, maintaining the optical axis alignment
Implementation Method 2
The heat from the light sources is transferred to the guide element and from there to the masks and disc. At least thermally, the guide element is connected to the masks and thus to the pane
Data Source
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AI summary
The signboard (10) has a front plate (12) comprising masks (16), via which translucent areas are separated from non-translucent areas. The translucent areas are provided in a transparent disk (14), and the masks are attached on a side of the disk, where the side is distanced from light sources e.g. LEDs or laser diodes. Additional masks coincide with the former masks, and are attached on another side of the disk, where the latter side is adjacent to the light sources. The LEDs are designed as surface mounted device-chips, and the masks are designed as black foils.