Ultrasonic Welding for Backlight Membrane Keyboard Alignment

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Solution Overview

Problem

Membrane keyboards for laptops lack functionality in low-light environments due to the absence of a backlight system, and existing solutions with adhesive assembly methods often result in misalignment of components, reducing yield.

Innovation Solution

A membrane keyboard design featuring a plastic key housing, membrane, dome-shaped insulative elastic members, scissor-shaped structures, membrane circuit board with LEDs, insulative plate, light guide membrane plate, and base plate, all aligned and secured together using ultrasonic welding for uniform backlighting and improved assembly precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If adhesive assembly method is used to assemble keyboard components, then assembly process is simple, but component alignment precision deteriorates

Engineering Contradiction:

Improveassembly process simplicityVSAvoidcomponent alignment precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent replaces the adhesive bonding method with ultrasonic welding technology. The ultrasonic welding device uses high-frequency mechanical vibration to melt and bond the membrane and key cover, eliminating the need for adhesives. This substitution resolves the contradiction by providing both precise alignment control through the welding process and strong bonding without the misalignment issues associated with adhesive methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the bonding method from chemical (adhesive) to physical (ultrasonic welding). By controlling parameters such as welding time, amplitude, and pressure, the system achieves precise component alignment while maintaining assembly simplicity. The ultrasonic welding parameters can be precisely controlled to ensure accurate positioning of the membrane and key cover relative to each other and to the circuit board.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If adhesive is used to secure components, then assembly complexity is reduced, but assembly reliability deteriorates

Engineering Contradiction:

Improveassembly complexityVSAvoidassembly reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent replaces adhesive bonding with ultrasonic welding, which creates a stronger and more reliable bond between components. The ultrasonic welding process melts the thermoplastic materials and fuses them together, creating a bond that is more reliable than adhesive bonding. This resolves the contradiction by maintaining simple assembly procedures while significantly improving assembly reliability through the superior bonding mechanism.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If backlight components are added to enable low-light operation, then functionality in low-light environments is improved, but assembly alignment precision deteriorates

Engineering Contradiction:

Improvelow-light functionalityVSAvoidassembly alignment precision

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent uses ultrasonic welding to assemble the backlight components (LEDs and light guide) with the keyboard structure. The ultrasonic welding process provides precise alignment control, ensuring that the LEDs are correctly positioned relative to the light guide and key switches. This resolves the contradiction by enabling low-light functionality through backlight integration while maintaining high assembly alignment precision through the controlled welding process.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

The solution provides a membrane keyboard with uniform key illumination in low-light conditions and enhances assembly reliability by ensuring precise alignment and strong bonding of components through ultrasonic welding, improving yield and functionality.

Implementation Method 1

the membrane, the key support plate, the membrane circuit board, the insulative plate, and the light guide membrane plate are subsequently subjected to ultrasonic welding to be bound together

Methodology Applied

Scientific EffectUltrasonic welding: Ultrasonic Vibration

Data Source

PatentUS8247714B2Back lighted membrane keyboard with components being secured together by subjecting to ultrasonic welding

Publication Date: 2012.08.21 SUNREX TECH

AI summary

A back lighted membrane keyboard includes a key housing, a membrane, a key support plate, a membrane circuit board, an insulative plate, a light guide membrane plate, and a base plate. The key housing, the membrane, the key support plate, the membrane circuit board, the insulative plate, and the light guide membrane plate are aligned by inserting stems thereinto. Eventually, these components are subjected to ultrasonic welding to be bound together.