IEC TR 62778:2012

IEC/TR 62778


®


Edition 1.0 2012-06



TECHNICAL



REPORT



RAPPORT
TECHNIQUE
colour
inside


Application of IEC 62471 for the assessment of blue light hazard to light sources
and luminaires

Application de la CEI 62471 aux sources de lumière et aux luminaires pour
l’évaluation du risque lié à la lumière bleue

IEC/TR 62778:2012

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IEC/TR 62778



®



Edition 1.0 2012-06







TECHNICAL





REPORT








RAPPORT



TECHNIQUE
colour

inside











Application of IEC 62471 for the assessment of blue light hazard to light sources

and luminaires




Application de la CEI 62471 aux sources de lumière et aux luminaires pour

l’évaluation du risque lié à la lumière bleue

















INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE

PRICE CODE
INTERNATIONALE

CODE PRIX V


ICS 29.140 ISBN 978-2-83220-146-6



Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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– 2 – TR 62778 © IEC:2012



CONTENTS




FOREWORD . 4

1 Scope . 6

2 Normative references . 6

3 Terms and definitions . 6


4 General . 10

5 Spectrum, colour temperature, and blue light hazard . 12
5.1 Calculation of blue light hazard quantities and photometric quantities from
emission spectra . 12
5.2 Luminance and illuminance regimes that give rise to t values below 100 s . 14
max
6 LED packages, LED modules, lamps and luminaires . 16
7 Measurement information flow . 17
7.1 Basic flow . 17
7.2 Conditions for the radiance measurement . 19
7.3 Special cases (I): Replacement by a lamp or LED module of another type . 21
7.4 Special cases (II): Arrays and clusters of primary light sources . 22
8 Risk group classification . 22
Annex A (informative) Geometrical relations between radiance, irradiance and radiant
intensity . 23
Annex B (informative) Distance dependence of t for a certain light source . 25
max
Annex C (informative) Summary of recommendations to assist the consistent
application of IEC 62471 for the assessment of blue light hazard to light sources and
luminaires . 27
Annex D (informative) Detailed assessment of arrays and clusters of primary light
sources, e.g. LED packages . 31
Bibliography . 32

Figure 1 – Blue light hazard efficacy of luminous radiation, K , for a range of light
B,v
sources from different technologies, and for a few typical daylight spectra . 13
Figure 2 – Comparison between the curves involved in calculating K (the photopic
B,v
eye sensitivity curve and the blue light spectral weighting function) and the CIE 1931 Y
and Z curves involved in calculating the CIE 1931 x, y colour coordinates . 14

Figure 3 – Correlation plot between the quantity (1 – x – y)/y, calculated from the CIE
1931 x, y colour coordinates, and the value of K , for all the spectra analyzed to
B,v
generate Figure 1 . 14
.
2
Figure 4 – Estimate of the luminance level where L = 10 000 W/(m sr), border
B
between RG1 (t > 100 s) and RG2 (t < 100 s) in the large source regime, as a
max max
function of CCT . 15
2
Figure 5 – Estimate of the illuminance level where E = 1 W/m , border between RG1
B
> 100 s) and RG2 (t < 100 s) in the small source regime, as a function of CCT . 15
(t
max max
Figure 6 – Relation of illuminance E, distance d and intensity I . 19
Figure 7 – Flow chart describing the flow of information from the primary light source
(in blue) to the luminaire based on this light source (in amber). 21
Figure A.1 – Schematic image of the situation considered in Annex A . 23
Figure B.1 – General appearance of t as a function of viewing distance d, for any
max
light source with homogeneous luminance L and diameter D . 26

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TR 62778 © IEC:2012 – 3 –


Figure C.1 – Luminance values from Table C.1 in relation to the RG1/RG2 border as

function of correlated colour temperature . 28

Figure C.2 – Illuminance values from Table C.2 in relation to the RG1/RG2 border as

function of correlated colour temperature . 29




Table 1 – Correlation between exposure time and risk group . 9

Table C.1 – Luminance values giving risk group not greater than RG1 . 28

Table C.2 – Illuminance values giving risk group not greater than RG1 . 29

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– 4 – TR 62778 © IEC:2012


INTERNATIONAL ELECTROTECHNICAL COMMISSION


____________




APPLICATION OF IEC 62471 FOR THE ASSESSMENT OF

BLUE LIGHT HAZARD TO LIGHT SOURCES AND LUMINAIRES



FOREWORD


1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected

data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC 62778, which is a technical report, has been prepared by subcommittee 34A: Lamps, of
IEC technical committee 34: Lamps and related equipment.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
34A/1541/DTR 34A/1566/RVC

Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

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TR 62778 © IEC:2012 – 5 –


The committee has decided that the contents of this publication will remain unchanged until

the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data

related to the specific publication. At this date, the publication will be


• reconfirmed,

• withdrawn,

• replaced by a revised edition, or

• amended.





IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates that it
contains colours which are considered to be useful for the correct understanding of its
contents. Users should therefore print this document using a colour printer.

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– 6 – TR 62778 © IEC:2012


APPLICATION OF IEC 62471 FOR THE ASSESSMENT OF

BLUE LIGHT HAZARD TO LIGHT SOURCES AND LUMINAIRES







1 Scope



This Technical Report brings clarification and guidance concerning the assessment of blue
light hazard of all lighting products which have the main emission in the visible spectrum

(380 nm to 780 nm). By optical and spectral calculations, it is shown what the photobiological

safety measurements as described in IEC 62471 tell us about the product and, if this product
is intended to be a component in a higher level lighting product, how this information can be
transferred from the component product (e.g. the LED package, the LED module, or the lamp)
to the higher level lighting product (e.g., the luminaire).
A summary of recommendations to assist the consistent application of IEC 62471 to light
sources and luminaires for the assessment of blue light hazard is given in Annex C.
NOTE It is expected that HID and LED product safety standards will make reference to this Technical Report.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60050-845:1987, International Electrotechnical Vocabulary – Part 845: Lighting
IEC 62471:2006, Photobiological safety of lamps and lamp systems
CIE S 017/E:2011, ILV: International Lighting Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 62471:2006 and
CIE S 017/E:2011 as well as the following apply.
NOTE Other terms and definitions related to lamps, LED modules and luminaires are to be found in the relevant
standards.
3.1
blue light hazard efficacy of luminous radiation
K
B,v
quotient of blue light hazard quantity to the corresponding photometric quantity
Note 1 to entry: The blue light hazard efficacy of luminous radiation is expressed in W/lm.
Note 2 to entry: The quantity Φ (λ) in the formula below can be replaced by L (λ) or E (λ).
λ λ λ
Φ (λ)⋅B(λ)⋅ dλ
λ
∫
K =
B,v
K ⋅ Φ (λ)⋅V(λ)⋅ dλ
m λ
∫
where K = 683 lm/W.
m
Note 3 to entry: KB,v = LB/L = EB/E.

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TR 62778 © IEC:2012 – 7 –


3.2

blue light hazard efficiency of radiation


B

ratio of blue light hazard quantity to the corresponding radiometric quantity


Note 1 to entry: The quantity  () in the formula below can be replaced by L () or E ().
  

Φ λ B λ dλ
( ) ( )
η
λ


Φ λ dλ
B
( )
λ



3.3
correlated colour temperature
CCT
temperature of the Planckian radiator having the chromaticity nearest the chromaticity
associated with the given spectral distribution on a diagram where the (CIE 1931 standard
observer based) u’, 2/3 v’ coordinates of the Planckian locus and the test stimulus are
depicted
Note 1 to entry: The correlated colour temperature is expressed in K.
Note 2 to entry: The concept of correlated colour temperature should not be used if the chromaticity of the test
4
1
2 2
[ ] 2 5 10
2 
source differs more than 9 from the Planckian radiator, where
ΔC (u'u' )  (v'v' )  
t p t p

u’ , v’ refer to the test source, u’ , v’ to the Planckian radiator.
t t p p
Note 3 to entry: Correlated colour temperature can be calculated by a simple minimum search computer program
that searches for that Planckian temperature that provides the smallest chromaticity difference between the test
chromaticity and the Planckian locus, or e.g. by a method recommended by Robertson, A. R. “Computation of
correlated color temperature and distribution temperature”, J. Opt. Soc. Am. 58, 1528-1535, 1968.
(Note that the values in some of the tables in this reference are not up-to-date).
[SOURCE: CIE S 017/E:2011, 17-258, modified: T is not referenced.]
cp
3.4
illuminance (at a point of a surface)
E
quotient of the luminous flux dΦ incident on an element of the surface containing the point, by
the area dA of that element
2
Note 1 to entry: The illuminance is expressed in lm/m = lx.
[SOURCE: IEC 60050-845:1987, 845-01-38]

3.5
blue light weighted irradiance

E
B
irradiance spectrally weighted with the blue light spectral weighting function as defined in
IEC 62471
2
Note 1 to entry: The blue light weighted irradiance is expressed in W/m .
3.6
threshold illuminance
E
thr
threshold illuminance value, below which the light source can never give rise to t  100 s,
max
regardless of the light source’s L value
B
Note 1 to entry: It can be calculated by taking the E value for t = 100 s, which is E = 1 W/m², and dividing it
B max B
by the K value corresponding to the spectrum of the light source.
B,v

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– 8 – TR 62778 © IEC:2012


2
Note 2 to entry: The threshold illuminance is expressed in lm/m = lx.


3.7

etendue
geometrical property of a collection of light rays in an optical system, given by the integral

over all positions in a plane that these light rays pass through and over all directions into

which they travel


Note 1 to entry: It takes the form of a product of area and solid angle, unit: m²sr. It can be seen as a volume in

phase space. Basic physical conservation laws, related to the ‘Second Law of Thermodynamics’, dictate that

optical components that change only the direction of light (lenses, reflectors, all beam shaping optics) can never
decrease the etendue for a given packet of flux.


Note 2 to entry: The etendue is expressed in m²sr.
3.8
irradiance (at a point of a surface)
E
e
quotient of the radiant flux dΦ incident on an element of the surface containing the point, by
e
the area dA of that element
2
Note 1 to entry: The irradiance (at a point of a surface) is expressed in W/m .
Note 2 to entry: The spectral power distribution of the irradiance, as a function of wavelength, is denoted by
E (λ).
λ
Note 3 to entry: For the purposes of this document, it is important to mention that when E (λ) is known, it can be
λ
converted to illuminance (E) when weighted with the CIE 1924 photopic eye sensitivity spectrum V(λ), and to blue
light weighted irradiance (E ) when weighted with the blue light spectral weighting function as defined in
B
IEC 62471.
[SOURCE: IEC 60050-845:1987, 845-01-37, modified: Note 2 and Note 3 introduced.]
3.9
luminance (in a given direction, at a given point of a real or imaginary surface)
L
quantity defined by the formula
dΦ
L=
dA⋅ cosθ⋅ dΩ
where dΦ is the luminous flux transmitted by an elementary beam passing through the given
point and propagating in the solid angle dΩ containing the given direction; dA is the area of a
section of that beam containing the given point; θ is the angle between the normal to that
section and the direction of the beam

Note 1 to entry: The illuminance (in a given direction, at a given point of a real or imaginary surface) is expressed
2
in cd/m .
[SOURCE: IEC 60050-845:1987, 845-01-35, modified: “L” instead of “L ” is used. The notes of
V
845-01-34 are not referred to.]
3.10
blue light weighted radiance
L
B
radiance spectrally weighted with the blue light spectral weighting function as defined in
IEC 62471
.
2
Note 1 to entry: The blue light weighted radiance is expressed in W/(m sr).
3.11
light source
any product that produces light, be it e.g. an LED package, an LED module, a lamp, or a
luminaire

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TR 62778 © IEC:2012 – 9 –


3.12

luminaire

apparatus which distributes, filters or transforms the light transmitted from one or more lamps

and which includes, except the lamps themselves, all the parts necessary for fixing and

protecting the lamps and, where necessary, circuit auxiliaries together with the means for

connecting them to the electric supply

[SOURCE: IEC 60050-845:1987, 845-10-01]


3.13

luminaire optics

all luminaire components that modify the spatial and directional characteristics of the radiation

emitted by the primary light source inside the luminaire
3.14
primary light source
surface or object emitting light produced by a transformation of energy
Note 1 to entry: For the purpose of this document, it may refer to an LED package, an LED module, or a lamp.
[SOURCE: IEC 60050-845:1987, 845-07-01]
3.15
radiance (in a given direction, at a given point of a real or imaginary surface)
L
e
quantity defined by the formula
dΦ
e
L =
e
dA⋅cosθ⋅ dΩ
where dΦ is the radiant flux transmitted by an elementary beam passing through the given
e
point and propagating in the solid angle dΩ containing the given direction; dA is the area of a
section of that beam containing the given point; θ is the angle between the normal to that
section and the direction of the beam.
Note 1 to entry: The radiance (in a given direction, at a given point of real or imaginary surface) is expressed in
.
2
W/(m sr).
Note 2 to entry: The spectral power distribution of the radiance, as a function of wavelength, is denoted by L (λ).
λ
Note 3 to entry: For the purposes of this document, it is important to mention, that when L (λ) is known, it can be
λ
converted to luminance (L) when weighted with the CIE 1924 photopic eye sensitivity spectrum V(λ), and to blue
light weighted radiance (L ) when weighted with the blue light spectral weighting function as defined in IEC 62471.
B
[SOURCE: IEC 60050-845:1987, 845-01-34, modified: Notes 1 to 5 have been dropped, new

notes are introduced.]
3.16
risk group
RG
risk classification when the product, at the relevant evaluation position, gives rise to a certain
t value, according to Table 1, as defined in IEC 62471:
max
Table 1 – Correlation between exposure time and risk group
Risk group number Risk group name Corresponding t range (s)
max
RG0 Exempt
> 10 000
RG1 Low risk 100 to10 000
RG2 Moderate risk 0,25 to100
RG3 High risk
< 0,25

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– 10 – TR 62778 © IEC:2012





3.17

maximum permissible exposure time
t
max
maximum permissible exposure time as calculated using the relevant formulae in 4.3.3 and

4.3.4 of IEC 62471


3.18

true luminance

luminance value as obtained by integrating the equation as given in the definition of

luminance according to IEC 60050-845, definition 845-01-35, over a certain area of a light

source, such that only the light emitting surface (or part of it) is included in the integration,
and no dark surface area surrounding the light emitting part of the light source
Note 1 to entry: When a luminance measurement is performed over a certain field of view, it will only give a true
luminance value when the field of view underfills the light emitting part of the light source.
3.19
true radiance
radiance value as obtained by integrating the equation as given in the definition of radiance
according to IEC 60050-845, definition 845-01-34, over a certain area of a light source, such
that only the light emitting surface (or part of it) is included in the integration, and no dark
surface area surrounding the light emitting part of the light source
Note 1 to entry: When a radiance measurement is performed over a certain field of view, it will only give a true
radiance value when the field of view underfills the light emitting part of the light source.
3.20
LED package
one single electrical component encapsulating principally one or more LED dies, possibly with
optical elements and thermal, mechanical, and electrical interfaces
Note 1 to entry: The component does not include the control unit of the controlgear, does not include a cap, and
is not connected directly to the supply voltage.
Note 2 to entry: A LED package is a discrete component and part of the LED module. For a schematic build-up of
1
a LED package, see Annex A of IEC/TS 62504 .
4 General
IEC 62471 is a comprehensive horizontal standard, describing all potential health hazards
associated with artificial optical radiation, from the ultraviolet, visible, and infrared portions of
the spectrum. This Technical Report deals exclusively with the hazard described in 4.3.3 and

4.3.4 of IEC 62471:2006. This hazard is called the retinal blue light hazard, as it is an effect
mainly induced by the blue portion of the visible spectrum, which has its potentially damaging
effects on the retina. The effects are described in Clause A.3 to the same standard.
Because the effect takes place on the retina, it is a function not only of the total amount of
light that reaches the eye, but also of the size of the light source that produced this light.
Larger light sources are imaged onto a larger portion of the retina, and therefore produce a
lower irradiance on the retina than smaller light sources producing the same amount of light in
the direction of the viewer’s eye. Subclause 4.3.3 of IEC 62471:2006 takes this into account
by relating the maximum permissible exposure time, t , to the radiance of the light source.
max
.
2
Radiance (unit: W/(m sr) ) is a quantity describing the radiometric intensity, which is the
radiati
...