Proximity-Sensitive Display Light Guide With Hidden IR Sensing
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Solution Overview
Problem
Existing proximity sensitive display elements obscure indicator structures when capacitive control elements are integrated, making it difficult for users to associate control elements with their corresponding functions intuitively.
Innovation Solution
Incorporating an infrared sensor within a light guide that is positioned in front of the indicator window, allowing for proximity sensing without obscuring the indicator structure, and using a semi-transparent patch in the reflective layer to conceal the sensor while receiving sufficient IR radiation for accurate response, with optional tuning of sensitivity through material properties or grid patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If capacitive control elements are integrated into the indicator window, then proximity sensing capability is improved, but the indicator structure becomes obscured
Solution Approach 1:
The sensor is positioned at the rear of the light guide rather than in the front indicator window, utilizing the depth dimension of the light guide structure. This allows the sensor to function through the semi-transparent reflective layer without visually obstructing the indicator structure from the user's perspective.
Solution Approach 2:
A semi-transparent reflective layer is introduced as an intermediary between the sensor and the external environment. This layer allows infrared radiation to pass through to the sensor while simultaneously concealing the sensor from visual view, thus mediating between the conflicting requirements of sensing capability and visual clarity.
2Measurement precision
If the sensor is positioned in front of the indicator window, then sensitivity to human touch is improved, but the sensor obscures the indicator structure
Solution Approach 1:
The sensor is relocated from the front surface to the rear surface of the light guide, utilizing the third dimension (depth) to resolve the conflict. The sensor maintains its sensitivity to infrared radiation from human touch while being positioned in a location that does not visually obstruct the indicator structure.
Solution Approach 2:
The reflective layer is designed with spatially varying properties: it is semi-transparent in the region where the sensor is located to allow IR radiation transmission, while maintaining its reflective function in other regions. This local differentiation allows the sensor to function without visual obstruction.
3Extent of automation
If the reflective layer is made transparent to allow sensor operation, then sensor functionality is improved, but light distribution and homogeneity deteriorate
Solution Approach 1:
The reflective layer is designed with spatially varying properties: it is semi-transparent only in the specific region where the sensor is located, while maintaining full reflectivity in other regions. This localized transparency allows sensor operation without compromising the overall light distribution and homogeneity of the illuminated indicator structure.
Solution Approach 2:
The optical properties of the reflective layer are carefully tuned in the sensor region to achieve semi-transparency that allows sufficient infrared radiation transmission while minimizing impact on visible light distribution. Material composition or structural parameters are adjusted to achieve the desired balance between sensor functionality and optical performance.
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
Enables intuitive user interaction by allowing control elements to coincide with indicator structures without obscuring them, providing high sensitivity and selective light distribution while maintaining visual feedback through the human finger, even under varying environmental conditions.
Implementation Method 1
an infrared sensor within the light guide, with its active side facing the first main side through a semi-transparent patch in the second reflective layer
Implementation Method 2
a light emitting element embedded in the substrate at its second main side to generate optical radiation in the light guide
Implementation Method 3
The first and the second reflective layer each have a reflective inner surface facing inside the light guide
Data Source
AI summary
A proximity sensitive display element (1) is provided that comprises a light guide (10), at least one light emitting element (30) and at least one infrared radiation sensor (40). The light guide (10) comprises a substrate (11) with a first and a second mutually opposite main sides (12, 14), respectively having a first and a second reflective layer (22, 24), with a reflective inner surface (222, 242) facing inside the light guide. At least one window (16) is defined in the first main side to allow optical radiation to enter and to leave the light guide. The at least one light emitting element (30) is typically embedded in the substrate at its second main side to generate optical radiation in said light guide. The at least one IR-sensor (40) is arranged at the second main side of the substrate and faces the first main side through a semi-transparent patch (240) in the second reflective layer (24).