Circuit Board Copper Foil LED Mounting Tilt
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Solution Overview
Problem
The use of chip LEDs in pre-exposing devices with light guides results in assembly accuracy issues, reduced light reflectance, and inadequate heat dissipation due to their weak directivity and low luminous intensity, as well as structural limitations such as solder cracks and electrode peeling, which are not addressed by existing methods that rely on mold components for bullet-shaped LEDs.
Innovation Solution
A circuit board design with first and second contact portions and electroconductive patterns that allow precise assembly, enhanced light reflectance by using solid copper foil patterns for improved light emission and heat dissipation, and alternative marking methods like cutting out the resist layer for identification symbols to prevent tilting and ensure accurate mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If chip LEDs are used in pre-exposing devices with light guides, then cost and space are reduced, but assembly accuracy deteriorates due to weak directivity and low luminous intensity
Solution Approach 1:
The patent introduces a light guide as an intermediary component between the chip LED and the photosensitive drum. The light guide receives light from the chip LED and guides it to uniformly illuminate the photosensitive drum, compensating for the weak directivity and low luminous intensity of chip LEDs while maintaining their cost and space advantages.
Solution Approach 2:
The patent changes the optical parameters by using a light guide with specific refractive index and geometric structure. This transforms the light distribution pattern from the chip LED's weak and diffuse emission into a controlled, uniform illumination pattern across the photosensitive drum surface.
2Illumination intensity
If chip LEDs with strong directivity are used, then luminous intensity increases, but assembly accuracy becomes critical due to sensitivity to optical axis tilt
Solution Approach 1:
The light guide acts as a mediator that decouples the chip LED from direct contact with the photosensitive drum. Even if the chip LED's optical axis is slightly tilted, the light guide redistributes the light to achieve uniform illumination, reducing the impact of assembly errors on luminous intensity distribution.
Solution Approach 2:
The light guide structure is designed in advance to compensate for potential assembly errors. Its geometric configuration and refractive properties are optimized to cushion against optical axis tilt and maintain uniform light distribution across the photosensitive drum.
3Ease of manufacture
If bullet-shaped LEDs are replaced with chip LEDs, then cost and size are reduced, but light reflectance and heat dissipation performance deteriorate
Solution Approach 1:
The light guide serves as an intermediary that improves light reflectance efficiency. It captures and redirects light that would otherwise be lost, directing more light uniformly onto the photosensitive drum while also providing a thermal management interface for heat dissipation.
Solution Approach 2:
The patent employs composite material structures in the light guide assembly, combining materials with different optical and thermal properties. This composite structure enhances both light reflectance and heat dissipation capabilities while maintaining the compact size and low cost advantages of chip LEDs.
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 enables highly accurate assembly of chip LEDs on a circuit board, increases light reflectance in the optical axis direction, and enhances heat dissipation, addressing the limitations of chip LEDs in pre-exposing devices.
Implementation Method 1
Light is projected from an LED to the light guide from one end of the light guide, and is reflected by grooves in the light guide. In this way, the light is uniformly emitted to the photosensitive drum in the longitudinal direction.
Implementation Method 2
The bullet-shaped LED includes, in its bullet part, a clear mold functioning as a lens to converge light from an LED chip, and thus achieves strong directivity
Data Source
AI summary
The circuit board has a surface mount LED with a lens on the circuit board. A conductive portion and remaining space in the periphery of the LED are covered with solid copper foil so that reflectance of light and a heat dissipation effect are enhanced. In addition, layer structures between the circuit board and an assembled component are the same between contact portions with the assembled component so that tilt in mounting the board is suppressed. As a result, the circuit board having mounted thereon the surface mount LED having high directivity can be accurately mounted on the assembled component, tilt of an optical axis can be suppressed, the reflectance of light from the LED can be increased, and the heat dissipation effect can be enhanced.