What are strengths of Stanley Electric's UV-C technology

         
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Optical technology developed
for automotive headlamps

Stanley Electric has been engaged in the manufacture and sale of automotive headlamps for 100 years since it was founded in 1920, and has been pursuing pioneering products to meet the needs of the times. Automotive headlamps are a critical component to secure safety of human life so they need to be of a high quality and highly reliable. We have continued to pursue proposals that exceed the requirements of automobile manufacturers, based on our strength of being able to in-house produce items from light sources (LEDs) to modules and finished products. We have also consistently developed items from light sources to finished products in the UV-C business, and have been working on research and development that uses basic technologies developed in the automotive lamp business. Here we will introduce the two basic technologies of thermal management and optical design, which are considered to be particularly important, from the two aspects of automotive lamps and UV-C technology.

Thermal management technology

For disinfection products with UV-C LEDs, thermal management of LEDs is one of the technical issues to be solved for designing such things as modules and finished products. Power inputted to an LED is converted to energy of light and heat, and any energy other than that outputted as light is lost as heat. This lost heat causes the temperature of the component to rise and shortens the life of the LED. Therefore, thermal management technology that includes the substrate where the LED is mounted and the surrounding module is a key point to maintaining highly efficient and high quality LED performance.

UV-C LED reactor heat dissipation

The UV-C LED reactor has three components to dissipate heat. A heat dissipation substrate to supply power to the LED while simultaneously allowing heat to escape, and a metallic heat sink that discharges heat efficiently. These two components are used as electronic devices for personal computers. The third is a fan used to improve the heat dissipation performance by directly blowing air onto the heat sink. Appropriate thermal management is achieved by combining these three parts to maximize their performance.

深紫外LEDリアクター
深紫外LEDリアクター

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To achieve downsizing and lightweight of heat dissipation parts

Stanley Electric has implemented theoretical design and thermal fluid analysis based on the theory of fluid dynamics and heat transfer optics at the stage before creating the shape as an object in order to optimize the heat dissipation path of the entire system. We have used a simulation to analyze a system that can easily transfer heat between components and efficiently dissipate heat to the external air [See Fig.2].

Stanley Electric has pursued technology to advance performance while making components as small and light as possible to meet the needs of automotive headlamps. And this technology is adopted in UV-C LED reactors to optimize the shape and their functional characteristics.

Fig.2: An image showing thermal fluid simulation analysis

Fig.2: An image showing thermal fluid simulation analysis
Fig.2: An image showing thermal fluid simulation analysis

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How to achieve more efficient use of light

To maintain long life and performance of the reactors, we need to efficiently transfer the heat generated from the LED. To achieve this, at the initial design stage we used a mathematical formula to solve how well heat flows within the entire product, investigated the rough size and material of each heat dissipation component. Then used a 3D model to repeatedly discover and improve any problematic areas in the detailed structure before deriving the most optimal heat dissipating shape.

More than thermal management, Stanley Electric sees to achieve more efficient use of light, as next goal, by consistently developing produces from light sources to finished products. And we can pursue high efficiency of light by optimizing our design from many different perspectives.

Optical design

Optical design in automotive headlamps and UV-C LED products.

Reflection and refraction in optical control

Light goes straight as long as there are no obstructions but it has properties of refracting when there are areas with different densities in the path of the light. The reason you can see light deformed above an asphalt road on a hot summer day is due to the phenomena in which light is refracted when air density changes because of the rise in temperature. These properties of light are used by refractive optical systems that make use of lenses. Depending on the incident angle and exit angle of light entering and leaving the lens, the angle of refraction can be freely adjusted to bend the light. Moreover, a reflector uses a shiny surface to change the angle by reflecting the light that was moving in a straight line. In this fashion, the properties of an optical system referred to as refraction and reflection are used to create light distribution*1.

*1: Light distribution is the appropriate distribution of required light for a location where it should reach.

Fig.3: An image showing reflection and
refraction for a headlamp light source unit

図3 ヘッドランプ光源ユニットの反射と屈折イメージ
図3 ヘッドランプ光源ユニットの反射と屈折イメージ

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Using light distribution technology
developed for automotive headlamps

We have conducted a simulation of the design and used suitable parts and materials to freely control light. The ability to create light by combining optimal types and sizes of parts and materials to meet the needs and applications is a strength of Stanley Electric in the field of light distribution technology.
The development of Adaptive Driving Beam (ADB) is progressing rapidly as a headlamp technology in recent years. ADB is a technology that controls light when there are pedestrians and drivers in front of you to control and beam the required amount of light in places where it is needed. This technology enables the driver to always drive with the high beam turned on without causing trouble for other drivers such as dazzling them. Stanley Electric also deals in outdoor lighting and street lighting. Light pollution (various impact that occurs because there was insufficient consideration for the landscape and surrounding environment due to inappropriate light distribution and methods used to install lighting) is regarded as a problem in this field. Therefore, technology in terms of freely controlling light to distribute light optimally to only those places where it is needed is being used for outdoor and street lighting.

Light distribution technology for UV-C products

Light distribution technology is applied in the development of UV-C products. Ultraviolet light can disinfect bacteria and viruses while at the same time may also have an adverse effect on the human body. Different to visible light, ultraviolet light is not visible to the human eye so we cannot consciously avoid it. Stanley Electric freely controls UV-C irradiation using technology that optimizes light distribution to achieve the safe use of UV-C light sources.

A difference with automotive headlamps that use light distribution technology for UV-C products, is not possible to use resin(deteriorates due to UV)-based lenses. So reflector technology is important in controlling irradiation in the UV-C product.

For example, in the UV-C LED reactor equipped with many LEDs, the light is diffused over a wide range and it is not possible to control the irradiation, when only LEDs are used. This is where a mechanism is used that can control the light distributed from each LED to uniformly irradiate UV-C and disinfect such as water that flows into the pipe by optimally arranging a reflector together with many LEDs [See Fig.4].

Fig.4: Optical structure of UV-C LED reactor

図4 流水用UV-LEDリアクターの光学構造
図4 流水用UV-LEDリアクターの光学構造

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Fig.5: UV-C LED reactor irradiated surface

図5 流水用UV-LEDリアクターの照射面 
図5 流水用UV-LEDリアクターの照射面 

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A consistent design and production system
from light sources to
modules and finished products

In addition to the above mentioned thermal management and optical design, factors such as the light source shape, size and characteristics have an impact on the light distribution. Therefore, the ability to consistently in-house design and produce items from light sources to modules and finished products to match product characteristics while verifying such items is a strength of Stanley Electric and we believe it will continue to work to our advantage. We are also focusing on technology that improves the conversion efficiency of light and fine chromatic control that produces bright light, and have been contributing to such things as reducing carbon dioxide and power consumption when it comes to the global environment. Using our technical capability developed for automotive headlamps and wealth of experience, as well as our consistent design and production system, Stanley Electric will continue to promote technological innovation for light into the future to create new light that is useful to society.

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