Application Note

Light Emitting Diode

Nichia Lighting LEDfor Disinfection

Table of contents
1. Overview ................................................................... 2
2. NF2W585AR-P8 LEDs ............................................ 2
3. Light Transmittance of the Optical Components ...... 4
4. Summary ................................................................... 6

NF2W585AR-P8 refers to Nichia part number. The Nichia part number within thisdocument is merely Nichia’s part number for the Nichia product and is not related norbear resemblance to any other company’s product that might bear a trademark.

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Application Note
1. Overview

Figure 1. Appearance of Nichia’s
NF2W585AR-P8 LED

Figure 2. Reference Images of Situations
using LEDs for Disinfection

2. NF2W585AR-P8 LEDs
2.1 Properties of NF2W585AR-P8 LEDs
Figure 3 shows the emission spectra of a typical white LED 1 and a NF2W585AR-P8 LED. The
typical white LED uses an LED chip that emits blue light at a wavelength of 450nm and has a peakwavelength at 450nm. This typical white LED hardly emits light in the wavelengths below 420nm
that is effective for disinfection. On the other hand, the NF2W585AR-P8 LED uses an LED chip thathas a peak wavelength at 405nm and emits light in the wavelengths mainly between 380nm and420nm that is effective for disinfection.
Emission Intensity

Light Emitting DiodeIn recent years, it has been found that the light in the wavelength range from 380nm to 420nm has adisinfection effect. Since the light in this wavelength range has less energy than ultraviolet light, it isless effective for disinfection but it is less harmful to human health; therefore, it is thought that thelight in the wavelength range from 380nm to 420nm can be utilized for disinfection in situations
where ultraviolet light cannot be used.
Nichia’s NF2W585AR-P8 LED is a white LED where the light emitting device has a peak wavelength
within the wavelength range from 380nm to 420nm. Nichia has achieved the dual function ofilluminating and disinfecting objects by converting the light into white light with Nichia’s original
phosphor technology without losing the disinfection effect. This application note provides
information on Nichia’s NF2W585AR-P8 LED and precautions when using the LED.

NF2W585AR-P8 LED (4000K)
Typical White LED (4000K)

350 400 450 500 550 600 650 700 750 800
Wavelength (nm)Figure 3. Emission Spectrum Comparison

1

In this document, “a typical white LED” is defined as a white LED that uses blue chips that have a peak wavelength near 450nm and yellow
phosphors.

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Application Note
Ultraviolet light with a wavelength around 260nm (UV-C light) is often used to damage and inactivate
bacteria effectively. However, ultraviolet light with a short wavelength has a high energy and candamage not only bacteria but also the human body. On the other hand, the NF2W585AR-P8 LED
emits light with the peak wavelength of 405nm that is classified as visible light, and its energy ismuch lower than ultraviolet light (UV-C light). For the classification of the peak wavelengths of LEDs,
refer to Figure 4. Although the light of the NF2W585AR-P8 LED is less effective for disinfection ofbacteria than ultraviolet light, it can significantly reduce damage to the human body. In addition, theNF2W585AR-P8 LED emits white light and its color rendering index Ra, which indicates color
reproducibility, is over 80; therefore, this LED can fulfill the function as a white light source for atypical luminaire. In places where human activities take place, it is possible to maintain environments
where bacteria cannot actively proliferate by continuously illuminating the places with the white lightof the NF2W585AR-P8 LED.

Light Emitting DiodeDamage to the Human Body and Disinfection EffectSignificant
200|

Less Significant

280|

UV-C

315|

UV-B

Typical Ultraviolet LED for
Sterilization (280nm)

400|

UV-A

NF2W585AR-P8 LED(405nm)

500|

600|

700|

780 (nm)|Visible Light

Typical White LED
for Illumination (450nm)

Figure 4. Peak Wavelengths of LEDs
2.2 Precautions when Using the NF2W585AR-P8 LED
The NF2W585AR-P8 LED emits light containing light of a shorter wavelength (higher energy) thanthat of a typical white LED. For safe and effective use, the following precautions should be taken into
consideration when designing and handling the luminaire.
i. Disinfection Effect against Bacteria
The disinfection effect of the NF2W585AR-P8 LED is not effective against all bacteria. The
disinfection effect varies depending on the structure of the luminaire and/or the environment
where the luminaire is used. Verifications should be done against the target bacteria under thecondition where the luminaire is actually used.
ii. Light Absorption of Optical Components assembled in Luminaries
The optical components assembled in the luminaire may absorb the light between 380nm and420nm and the disinfection effect may not be fully achieved. When selecting optical components,
verifications should be done to ensure that the light between 380nm and 420nm sufficiently passes
through the optical components.
For reference, Nichia’s light transmittance measurement results are shown in Section 3.

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Application Noteiii. Effects on the Human Body
The NF2W585AR-P8 LED contains a small amount of UV-A ultraviolet light (315nm to 400nm).
Operating multiple LEDs at a high output at the same time or directly viewing or being exposedto the light condensed by the optical components for a long period of time may affect the eyes orhealth. Since the harmfulness of ultraviolet rays varies depending on the wavelength, irradiance,and exposure time during use, verifications should be done prior to use. In addition, it is necessary
to provide users with sufficient precautions depending on the intended use.

Light Emitting Diodeiv. Effects on the Materials/Components used with the NF2W585AR-P8 LED
Depending on the materials/components used with the NF2W585AR-P8 LED, UV-A ultraviolet
light (315nm to 400nm) may accelerate their degradation. Verifications should be done prior touse when selecting materials/components used for the luminaire. The degradation of the objects
irradiated with UV-A ultraviolet light may also be accelerated; therefore, sufficient precautions
should be taken. In addition, it is necessary to provide users with sufficient precautions dependingon the intended use.
v. Estimated Lifetime of the NF2W585AR-P8 LED
Since the NF2W585AR-P8 LED emits light containing light of a higher energy than that of atypical white LED, the degradation of the materials used in the NF2W585AR-P8 LED is more
accelerated than that of a typical white LED. Therefore, the lifetime of the NF2W585AR-P8 LED
is shorter than that of a typical white LED. For this reason, limiting the operating conditions suchas the input current may be required. If customers require the details of the lifetime ofNF2W585AR-P8 LED, contact a local sales representative.

3. Light Transmittance of the Optical ComponentsThe light transmittance of an object depends not only on its material but also on the wavelength of
the incident light. The shorter the wavelength is, the more light is absorbed inside the object, resulting
in a decrease in the light transmittance. The NF2W585AR-P8 LED has a peak wavelength of 405nm,
which is the shortest wavelength of visible light, and its light is easily absorbed by the opticalcomponents such as lenses and covers. For this reason, the disinfection effect may not be achieved
sufficiently. The following section shows the measurement results of the light transmittance fordifferent materials. Use these results for reference when selecting optical components.
3.1 Measurement Method
Measurement Samples:
See Table 1 for the materials and thickness of the samples.
The color is transparent (colorless) for all the samples.

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Application Note
Table 1. Measurement Samples
Thickness (mm)Material
Optical Grade Polycarbonate

1.0

1.52.0✔

✔

✔

General Grade Polycarbonate
Acrylic✔

Soda Glass✔

✔

3.0✔

✔

✔

✔

✔

✔

Measurement Method:
Measure the total amount of the light that is transmitted through a sample (sum of the light thatpasses straight through the sample and the light that diffuses through the sample). The percentageof the light that is transmitted through the sample to the incident light is defined as a lighttransmittance. Then, measure the light transmittance for each wavelength.
3.2 Measurement Results
Figures 5 to 7 show the measurement results.
100

Polycarbonate

80

Optical 1.0mm

60

Optical 1.5mm

Optical 2.0mm

40General 2.0mm
20General 3.0mm

0Light Transmittance (%)

Light Transmittance (%)

100

80

Acrylic
1.0mm

601.5mm402.0mm
3.0mm

200300350400450
Wavelength (nm)

500

300

Figure 5. Light Transmittance
Measurement Result (Polycarbonate)

350

400
450
Wavelength (nm)500

Figure 6. Light Transmittance
Measurement Result (Acrylic)

100
Light Transmittance (%)

Light Emitting Diode

Measurement Device:
UV-Visible Spectrophotometer U-3900 Manufactured by Hitachi High-Tech Corporation

80

Soda Glass
601.0mm
2.0mm

403.0mm200300

350

400
450
Wavelength (nm)500

Figure 7. Light Transmittance
Measurement Result (Soda Glass)This document contains tentative information, Nichia may change the contents without notice.
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Application Note
The comparison of the light transmittance between 380nm and 420nm, which is effective fordisinfection, indicates the following:- General grade polycarbonate has a low light transmittance, and the light intensity is significantly
reduced accordingly, resulting in a significant decrease in the disinfection effect.
- Optical grade polycarbonate has a high light transmittance and the decrease in the disinfection
effect can be minimized. The light transmittance slightly decreases when the polycarbonate plate
thickness increases.
- Acrylic also has a high light transmittance; however, the light transmittance slightly decreases
at the shorter wavelength (380nm).

Light Emitting Diode- Glass has a high light transmittance at all thicknesses.

These results were obtained from measurements using certain materials. Even if the same material isused in the optical components, their properties may be significantly different depending on the gradeof the material and/or the specifications of the optical component that is actually used. Generalluminaries usually use light diffusion covers with diffusion materials added or with surface processing
to reduce the glare of the light sources. For those cases, the light transmittance may become evenlower than these results.

4. Summary
The NF2W585AR-P8 LED is a product that has the characteristics of both a white LED for lighting
and an ultraviolet LED for disinfection. This LED is assumed to be used for a luminaire with adisinfecting effect; precautions are required since this LED needs to be used in a different mannerfrom a typical LED for a luminaire. When designing a luminaire using this LED, make sure that lightwith a wavelength between 380nm and 420nm, which is effective for disinfection, is sufficiently
emitted through the luminaire. In addition, verifications should be done against the target bacteria
under the conditions/environments where the luminaire is actually used. If customers have anyquestions regarding this product, contact a local sales representative.

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Application Note

Light Emitting DiodeDisclaimer
This application note is a controlled document of Nichia Corporation (Nichia) published to provide
technical information/data for reference purposes only. By using this application note, the user agrees
to the following: This application note has been prepared solely for reference on the subject matters incorporated
within it and Nichia makes no guarantee that customers will see the same results for their chosenapplication.
 The information/data contained herein are only typical examples of performances and/orapplications for the product. Nichia does not provide any guarantees or grant any license underor immunity from any intellectual property rights or other rights held by Nichia or third parties.
 Nichia makes no representation or warranty, express or implied, as to the accuracy, completenessor usefulness of any information contained herein. In addition, Nichia shall not be liable for any
damages or losses arising out of exploiting, using, or downloading or otherwise this document, or
any other acts associated with this document.
 The content of this application note may be changed without any prior or subsequent notice.
 Copyrights and all other rights regarding the content of this document are reserved by Nichia or
the right holders who have permitted Nichia to use the content. Without prior written consent of
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NICHIA CORPORATION
http://www.nichia.co.jp

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