Single-Sided PCB Illuminated Keyboard Switch Circuit
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Solution Overview
Problem
Existing illuminated mechanical keyboards require complex light guide structures or surface mount LEDs, which complicate manufacturing and increase costs, and often necessitate crossover connections on the PCB, making the design cumbersome.
Innovation Solution
A single-sided Printed Circuit Board (PCB) with a mechanical key structure incorporating a center-mounted LED eliminates the need for light guides and simplifies manufacturing by using a Plated Through Hole (PTH) LED with pins extending through the PCB, and incorporates low-ohm resistors to form bridges for switch matrix conductors, reducing the need for crossover connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light guide structure is used to illuminate keys, then illumination can be achieved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent extracts and removes the light guide component entirely from the keyboard assembly. Instead of using a separate light guide structure to distribute LED light across key surfaces, the design places LEDs directly on the PCB beneath each key, eliminating the need for light guides and their associated complexity while maintaining illumination functionality.
Solution Approach 2:
The patent merges the illumination function directly into the PCB structure by mounting LEDs on the PCB itself rather than using separate illumination components. This integration combines the lighting function with the existing PCB framework, reducing overall device complexity and simplifying manufacturing.
2Illumination intensity
If surface mount LEDs are used for illumination, then key lighting is achieved, but manufacturing complexity and costs increase
Solution Approach 1:
The patent employs through-hole mount LEDs instead of more expensive surface mount LEDs. Through-hole LEDs are generally less expensive, easier to manufacture with traditional PCB processes, and simpler to replace or repair, aligning with the principle of using cost-effective, easily replaceable components.
Solution Approach 2:
The patent replaces the complex surface mount LED attachment process with simpler through-hole mounting. This substitution uses traditional mechanical drilling and soldering processes that are more established and easier to implement in manufacturing compared to surface mount technology, reducing manufacturing complexity.
3Reliability
If crossover connections are made on the PCB for switch matrix conductors, then electrical connections are established, but PCB design complexity increases
Solution Approach 1:
The patent resolves conductor crossovers by utilizing the third dimension (vertical depth) of the PCB structure. Instead of having conductors cross over each other on the same plane which creates design complexity, the routing uses different layers or depths within the PCB, allowing conductors to pass beneath or above each other without interfering with the design.
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 simplifies the manufacturing process, eliminates the need for light guides, and reduces PCB complexity by ensuring the LED's light emitting surface is close to the keycap, allowing for efficient backlighting without additional components, thereby enhancing the design's efficiency and cost-effectiveness.
Implementation Method 1
An LED with pins for protruding through a printed circuit board is used
Data Source
AI summary
Embodiments of the present invention provide a circuit structure that allows the use of a single sided Printed Circuit Board (PCB) with a mechanical key structure that has a light emitting element in the middle of the key structure. An LED with pins for protruding through a printed circuit board allows a layout only on the bottom side of the PCB. In one embodiment, the PCB includes at least one low ohm resister forming a bridge for a switch matrix conductor over a perpendicular switch matrix conductor.