What is Light guide?

Light guide is an optical component that efficiently transmits light using internal reflection within a transparent resin. Its use in home appliances and industrial equipment has been growing.
Light guides help evenly illuminate areas away from the light source, where brightness would otherwise be uneven. There are two main types: injection-molded and optical fiber light guides.

Differences Between Injection-Molded Light Guides and Optical Fiber Light Guides

Features of Injection-Molded Light Guides

Injection-molded light guides are made by molding transparent resin materials such as PC (polycarbonate) or PMMA (acrylic).
Although a dedicated mold must be created for each product, the shape can be freely designed to suit the application—whether it’s a long and narrow guide or a round or rectangular lens.
Various light emission methods are available, including Prism, Blast, and Dot, allowing the direction and balance of light distribution to be adjusted according to customer requirements.

Features of Optical Fiber Light Guides

Optical fiber light guides are generally manufactured by extrusion molding, which limits the cross-sectional shape and size to a few specific types. However, unlike injection-molded light guides, they do not require custom molds for each product, so no initial tooling cost is incurred.
Thanks to their flexible material characteristics, fiber guides can be bent freely. They emit light uniformly in all directions, so complex optical design is not required.
However, they cannot focus light in a specific direction, nor can the brightness be varied along different sections. Additionally, a separate structure or component is needed to secure the fiber guide in place.

Three Key Features of Oshino's Light Guides

Our light guides are manufactured using the injection molding method, allowing for flexible shape design to suit your specific needs.
A variety of materials—such as PC (polycarbonate) and PMMA (acrylic)—are available based on your requirements. We offer multiple illumination methods, including Prism, Blast, and Dot, which can also be combined for customized lighting effects.
With these capabilities and technologies, Oshino delivers the optimal light guide solutions tailored to each customer’s needs.

1. Integrated Production from Design to Mass Manufacturing

Oshino’s light guides are manufactured using transparent resin injection molding.
We offer a fully integrated domestic production system in Japan—from proposal and design based on customer requirements, to mold design and fabrication, injection molding, and final inspection.
This enables us to deliver high-quality products with short lead times.

2. Specialized Factory for Transparent Resin Molding

Our production base is located in Yamanashi Prefecture, where we manufacture optical components in a clean environment specialized in transparent resin molding.

Yamanashi Factory

Light guide Production factory in Yamanashi, Japan

3. Global Design and Engineering Expertise

In addition to Japan, the Oshino Group has an optical design engineering team in Germany and a manufacturing facility in Estonia.
We provide interior lighting design and production for major European automotive manufacturers.
Leveraging our global expertise, we offer a wide range of ambient lighting solutions that incorporate advanced design and technology.

Development and Manufacturing Achievements

We have developed and produced a variety of light guides, mainly for automotive applications, but also for general industrial use. If you have a request such as “We want to illuminate this part,” please feel free to contact us for a consultation. Examples of Past Projects:

- Long light guides exceeding 700mm, emitting light in a thin, linear shape
- Light guides for backlit power window switches
- Round and square light guides for AUX and USB port illumination
- Lenses for in-vehicle map lamps
- Light guides for indicator lamps in security and disaster-prevention equipment, and more

Key Points When Choosing a Light Guide

Shape

If you want to create a uniform line of light, both optical fiber and injection-molded light guides are viable options.
Optical fibers are made from soft resin materials, making them highly flexible and easy to bend into the desired shape.
However, a separate structure is required to secure them in place.

Cost

Injection-molded light guides require the production of a mold, which results in initial tooling costs.
In contrast, optical fiber light guides do not require molds, making them more cost-effective for small-scale production.
However, for mass production of similar shapes, injection-molded light guides offer a clear cost advantage.

Light Emission Pattern

Optical fibers emit light in all directions along their length, while injection-molded light guides can be designed to direct light in specific directions.
Injection-molded types also support various emission techniques—including Prism, Blast, and Dot—which can be selected or combined based on your needs.

Types of Light Emission Methods
- Prism Method: Produces bright light but the pattern tends to be visible, making it less suitable for direct lighting. It is ideal for indirect lighting applications.

- Blast Method: Emits less light than the prism method but the pattern is not visible. Uniformity can be adjusted, making it suitable for direct lighting.

- Fiber Method: No visible pattern; suitable for direct lighting.

- Dot Method: Brighter than the blast method, and the pattern is less visible than with the prism method.

Blasting Process