Touch Key Assembly Light Guide Illumination
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Solution Overview
Problem
Conventional mobile terminals with light-emitting diodes (LEDs) for key buttons face issues of increased thickness due to space consumption and light obstruction by dome switches, leading to higher power requirements for adequate illumination.
Innovation Solution
A touch key assembly with an optically transmissive cover, a touch pad forming a light guide, and a light source positioned relative to the bottom side of the touch pad, along with an optional optical waveguide and reflection element, which reduces the need for multiple LEDs and minimizes thickness by efficiently guiding light to the touch keys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If LEDs are positioned within the gap between pad and circuit board to illuminate key buttons, then the key buttons are illuminated, but the thickness of the mobile terminal increases
Solution Approach 1:
The patent transitions from positioning LEDs vertically within the gap between pad and circuit board to positioning them laterally adjacent to the light guiding plate. This dimensional change allows light to be guided horizontally through the light guiding plate to the key buttons, eliminating the need for vertical space and reducing terminal thickness.
Solution Approach 2:
The patent introduces a light guiding plate as an intermediary component between the LED and the key buttons. The LED is positioned laterally, and the light guiding plate channels the light horizontally to illuminate the key buttons, solving both the illumination requirement and the thickness constraint.
2Illumination intensity
If the number of LEDs is increased to compensate for light blocked by dome switches, then adequate illumination is achieved, but power requirements increase
Solution Approach 1:
The light guiding plate serves as an efficient light transmission intermediary that directs LED light around the dome switches to illuminate key buttons. This eliminates the need to increase LED quantity to compensate for blocked light, thereby maintaining lower power requirements.
Solution Approach 2:
The patent segments the light transmission path by using the light guiding plate to channel light laterally, separating the LED positioning from the key button illumination path. This allows efficient light delivery without requiring additional LEDs to overcome obstruction.
3Illumination intensity
If LEDs protrude from the circuit board to provide illumination, then light can be emitted, but space is consumed increasing terminal thickness
Solution Approach 1:
The patent changes the spatial arrangement from vertical LED protrusion to lateral LED positioning adjacent to the light guiding plate. This dimensional reconfiguration eliminates the need for vertical protrusion space while maintaining effective light emission and transmission to the key buttons.
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 allows for effective illumination of touch keys with fewer light sources, reducing the overall thickness and power consumption of the mobile terminal while ensuring adequate lighting in dim environments.
Implementation Method 1
A light source is positioned relative to the bottom side of the touch pad, and is further positioned relative to the light guide to provide light to the touch key
Implementation Method 2
an optical waveguide positioned relative to the bottom side of the touch pad, the optical waveguide being structured to transmit light
Implementation Method 3
A reflection element operatively associated with the bottom side of the optical waveguide may be used to enhance refection of the light
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A touch key assembly is structured to operate with a cover having at least one touch key, which is defined by an optically transmissive region of the cover. A touch pad is coupled to the cover and is shaped to define at least one aperture which forms a light guide that is associated with the touch key. A light source is positioned relative to the bottom side of the touch pad, and is further positioned relative to the light guide to provide light to the touch key. The assembly may also include an optical waveguide positioned relative to the bottom side of the touch pad, the optical waveguide being structured to transmit light. A reflection element operatively associated with the bottom side of the optical waveguide may be used to enhance refection of the light. The touch key assembly may be implemented in a portable electronic device, such as a mobile terminal or a personal digital assistant (PDA).