Tinted Lens Reduces Conspicuity of Emergency Warning Lights
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Solution Overview
Problem
Conventional emergency vehicle warning lights with LED sources and clear lenses make internal structures visible, making them conspicuous when not in use, which is undesirable for unmarked law enforcement vehicles.
Innovation Solution
A tinted lens or cover with a neutral density 'smoke' additive is used to reduce light transmission equally across all colors, making the warning lights less conspicuous when inactive and reducing solar heating, while ensuring compliance with regulatory light output standards by adjusting the tint's light-blocking ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If clear lenses are used with LED light sources, then maximum light transmission is achieved, but internal structures become visible making the warning lights conspicuous when not in use
Solution Approach 1:
The patent applies a neutral density tint (grey or smoke color) to the lens that changes its light transmission properties. The tint is designed to block a predetermined portion of light (e.g., 18% blocked, 82% transmitted) to reduce conspicuity of internal structures when the warning light is not in use, while still allowing sufficient light transmission when activated to meet regulatory requirements. This color modification enables the lens to appear dull and less visible in the inactive state.
2Object-generated harmful factors
If tinted lenses are used to reduce conspicuity, then internal structures are obscured, but light output must be carefully controlled to meet regulatory standards
Solution Approach 1:
The patent modifies the optical parameters of the lens by incorporating a neutral density tint with specific light-blocking properties. The tint is formulated to block a predetermined percentage of light (e.g., 18% blocked, 82% transmitted) to achieve the desired balance between obscuring internal structures and maintaining sufficient light output when activated. This parameter adjustment allows the warning light to meet regulatory standards while reducing conspicuity when inactive.
3Illumination intensity
If clear lenses are used, then maximum light output is achieved, but solar heating of the enclosure increases
Solution Approach 1:
The neutral density tint (grey or smoke color) applied to the lens absorbs a portion of the solar radiation that would otherwise pass through a clear lens and heat the internal enclosure. By blocking a predetermined portion of light (e.g., 18% blocked), the tint reduces the thermal load on the warning light assembly during daytime operation, thereby reducing solar heating of the enclosure while still allowing sufficient light transmission when activated.
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 tinted lenses or covers effectively obscure internal components when not in use, reducing conspicuity and maintaining compliance with regulatory light output standards, ensuring the warning lights appear dull and less visible until activated, while also potentially reducing solar heating.
Implementation Method 1
A lens or cover that is tinted with a grey or 'smoke' additive formulated to block a predetermined portion of light. The tint is not spectrally selective or alternatively referred to as 'neutral density' in that it reduces transmission of all colors of light equally.
Implementation Method 2
Tinted lenses may also reduce solar heating of a warning light or lightbar enclosure.
Data Source
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AI summary
A warning light includes a lens or cover is tinted with a grey or "smoke" tint that is not spectrally selective or alternatively referred to as "neutral density" in that it reduces transmission of all colors of light equally. The objective of the neutral tinted "smoked" lens is to reduce the conspicuity of warning lights when not in use. Ambient light penetration into the warning light is reduced by the proportion of tint and then light reflecting off the optical surfaces within the warning light are reduced again when passing through the tinted lens on the way out of the assembly. The resulting warning light appears dull and is less conspicuous than the same warning light or lightbar with a clear lens. The tinted lens or cover may include optical elements configured to re-direct light, and the entire lens or cover is molded from the same tinted plastic material.