Vehicle Lamp Projector Lens Convex Connection Surface Glare Reduction

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

In vehicle lamps, light emitted from the light source unit can create glare due to light being reflected by the inside of the projector lens, leading to inaccurate light distribution and unwanted illumination of areas ahead of the vehicle.

Innovation Solution

The projector lens is designed with a convex connection surface that connects the incident and emission surfaces, allowing light to be internally reflected at a larger angle, reducing the likelihood of forward emission and minimizing glare by shaping the connection surface to be convex in section, including the optical axis, and potentially forming an arc or circular arc shape.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a plano-convex lens is used as the projector lens, then the lens structure is simple and easy to manufacture, but light incident on the outer peripheral portion is reflected by the inside of the side surface and emitted upwards, generating glare

Engineering Contradiction:
Improvelens structure simplicityVSAvoidglare generation
Core Design Contradiction:
Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The connection surface is designed with a convex curved shape instead of a flat surface. This curvature causes light incident on the outer peripheral portion to be reflected at larger angles toward the emission surface, preventing upward emission and glare generation while maintaining optical functionality.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

Different regions of the lens have different surface characteristics. The connection surface specifically has a convex shape in its radial cross-section, while other portions maintain standard lens geometry. This localized modification addresses the glare problem only where it occurs without complicating the entire lens structure.

Inventive Principle:
Principle #3Local quality

2Area of stationary object

If light is incident on the outer peripheral portion of the projector lens, then the light distribution coverage is expanded, but the light is reflected by the inside of the side surface and not emitted forwardly, reducing light distribution accuracy

Engineering Contradiction:
Improvelight distribution coverageVSAvoidlight distribution accuracy
Core Design Contradiction:
Area of stationary objectVSManufacturing precision

Solution Approach 1:

The convex curved connection surface redirects light from the outer peripheral portion at appropriate angles toward the emission surface, ensuring that expanded coverage areas contribute effectively to forward light distribution rather than being lost to side reflections.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The convex connection surface converts the harmful effect of light reflection (which previously caused glare and loss) into a beneficial effect by directing reflected light toward the emission surface at appropriate angles, improving overall light distribution efficiency.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 ensures accurate light distribution by preventing light from being emitted forwardly from the projector lens, thereby reducing glare and improving the vehicle's forward illumination pattern.

Implementation Method 1

the light emitted from the light source, incident on the incident surface and internally reflected by the connection surface reaches the emission surface with a larger incident angle than an incident angle with which light reaches a connection surface having a linear shape in section including the optical axis, so as to be apt to be totally reflected by the emission surface

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP2674665B1Lamp unit and projector lens for a vehicle lamp
Publication Date: 2020.04.01 KOITO MFG CO LTD
  • EP2674665B1 patent drawingFigure 1
  • EP2674665B1 patent drawingFigure 2A~2B
  • EP2674665B1 patent drawingFigure 3

AI summary

A lamp unit (10) is one for use in a vehicle lamp. The lamp unit (10) includes a light source mounting portion on which a light source is mounted, and a projector lens (100) that is disposed on a vehicle front side of the light source. The projector lens includes an incident surface (100a) on which light emitted from the light source is incident, a convex emission surface (100b) from which the light incident on the incident surface is emitted forwardly of the lamp, a connection surface (100c) that connects an edge part of the incident surface (100a) and an edge part of the emission surface (100b). The connection surface (100c) includes, at least in a partial area thereof, a convex surface that is convex, in section including an optical axis, outward in a diameter direction.