Optical Actuators in Keyboards for Backlight and Tactile Feedback
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Solution Overview
Problem
Existing keypad technologies face challenges in providing both sufficient tactile feedback and efficient optical illumination, especially in cost-sensitive applications like mobile phones, where manufacturing complexities and energy losses occur due to the integration of dome pins and light guides, leading to variability in optical quality and efficiency.
Innovation Solution
The integration of optical protrusions made of materials with scattering or color-absorbing particles attached to a planar light guide, which couple light out selectively and perform actuating functions when pressed, providing both tactile feedback and controlled illumination without compromising the mechanical key function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If dome pins with holes are used for mechanical key function, then tactile feedback is provided, but energy losses in illumination occur
Solution Approach 1:
The patent merges the dome pin structure with the light guide by integrating optical protrusions directly into the light guide. This eliminates the need for separate dome pins with holes, as the protrusions themselves serve both as mechanical actuation elements and optical components. The integration removes the harmful holes that caused energy losses while maintaining tactile feedback functionality.
Solution Approach 2:
The optical protrusions perform multiple functions simultaneously: they provide mechanical actuation for key press detection, serve as light out-coupling elements through their scattering particles, and enable spatially selective illumination. This multi-functionality eliminates the need for separate components and reduces energy losses associated with traditional dome pin structures.
2Ease of manufacture
If painted keysets are used for colored appearance, then cost is reduced, but optical quality varies and efficiency is lost
Solution Approach 1:
The patent applies local quality by incorporating scattering particles specifically within the optical protrusions at key locations rather than using general painted surfaces. This localized approach allows precise control of light out-coupling at each key position, ensuring consistent optical quality and efficiency while maintaining cost-effectiveness through targeted material placement.
Solution Approach 2:
The patent changes the optical parameters by incorporating scattering particles with specific properties into the protrusions. This allows control over light scattering characteristics, out-coupling efficiency, and spectral properties, providing consistent optical quality across different keys while avoiding the variability associated with painted surfaces.
3Ease of operation
If spatial structuring is limited to separate regions on light guide, then out-coupling modulation is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent combines the out-coupling control structure with the dome pin/light guide integration. The optical protrusions are formed as integral parts of the light guide structure, eliminating the need for separate structuring steps. This merging reduces manufacturing complexity while maintaining spatially selective out-coupling control through the protrusion geometry and scattering particle distribution.
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 enables spatially and spectrally selective light out-coupling, enhancing the visual appearance of keypad keys while maintaining tactile feedback, reducing manufacturing steps and energy losses, and offering more uniform and efficient illumination.
Implementation Method 1
The portion of light may be coupled out of the second surface by scattering on dispersed scattering particles comprised in the at least one protrusion
Implementation Method 2
the at least one protrusion may comprise color absorbing particles to enable selecting a pre-selected wavelength band of the portion of light coupled out of the second surface
Data Source
AI summary
The specification and drawings present a new apparatus and manufacturing method for optical protrusions (e.g., dome pins or actuators) attached to a light guide for providing backlight, actuation function and/or tactile feedback in keypad modules of electronic devices. Spatially and spectrally selective out-coupling of light from the light guide (e.g., a planar light guide plate) can be accomplished using these optical actuators integrated with the light guide for keypad illumination to control out-coupling efficiency and/or spectra of the out-coupled light to enable modification of the visual appearance (intensity, colored/white) of individual keys of the keypad.