Backlight Keyswitch Light Guide Structure for Uniform Symbol Illumination
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Solution Overview
Problem
Existing backlight keyswitches with low-power LEDs suffer from inconsistent illumination, where main symbols are over-illuminated while corner symbols are too dark, due to inefficient light distribution and excessive initial light loss.
Innovation Solution
The implementation of a backlight keyswitch design that includes a protrusion structure on the support plate, membrane circuit board, or shielding sheet, which reflects and scatters light from the LED to increase the light transmission angle and enhance lateral light transmission into the light guide panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a low-power LED is used to illuminate the keyswitch, then energy consumption is reduced, but illumination uniformity deteriorates (main symbol over-illuminated, corner symbols too dark)
Solution Approach 1:
The patent segments the light transmission path by introducing a light guide panel that divides and redirects light from the LED toward corner symbols, preventing direct over-illumination of the main symbol while delivering light to darker areas
Solution Approach 2:
The light guide panel acts as an intermediary between the LED and the keycap symbols, redirecting light paths to achieve more uniform illumination across different symbol locations without increasing energy consumption
2Loss of energy
If the light transmission angle is narrow, then light loss is reduced, but the area of illumination is limited
Solution Approach 1:
The light guide panel utilizes lateral light transmission in a horizontal dimension, allowing light to spread across a wider area of the keycap without requiring an increased vertical transmission angle, thus maintaining low light loss while expanding illumination coverage
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 design significantly improves lighting uniformity by increasing the amount of light reaching side and corner symbols, reducing initial light loss, and enhancing the visual effect of the backlight keyswitch.
Implementation Method 1
The protrusion structure reflects and scatters at least partial light of the light source to enter the light guide panel for lateral transmission
Implementation Method 2
The protrusion structure reflects and scatters at least partial light of the light source to enter the light guide panel for lateral transmission
Data Source
AI summary
A backlight keyswitch includes a keycap, a support plate, a membrane circuit board and a backlight module. The support plate is disposed under the keycap. The membrane circuit board is disposed in parallel to the keycap and the support plate. The backlight module is disposed under the support plate, which includes a shielding sheet, a light guide panel, a lighting board and a protrusion structure. The shielding sheet includes a light permeable area corresponding to the keycap. The light guide panel is disposed under the shielding sheet. The lighting board is disposed under the light guide panel and includes a light source. The protrusion structure protrudes toward the light source and is formed on one of the support plate, the membrane circuit board and the shielding sheet. The protrusion structure reflects at least partial light of the light source to enter the light guide panel for lateral transmission.