IEC 62595-2-5:2021
(Main)Display lighting unit - Part 2-5: Measurement method for optical quantities of non-planar light sources
Display lighting unit - Part 2-5: Measurement method for optical quantities of non-planar light sources
IEC 62595-2-5:2021 specifies the measurement methods for measuring the optical characteristics of convex and concave cylindrical light sources. These non-planar light sources (NPLSs) can have either a continuous, distinct, segmented or block-wised light radiating surface, for example OLED panels, integrated LEDs, integrated mini-LEDs, micro-LEDs, laser diodes, each being either monochromatic or polychromatic.
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Standards Content (Sample)
IEC 62595-2-5 ®
Edition 1.0 2021-05
INTERNATIONAL
STANDARD
colour
inside
Display lighting unit –
Part 2-5: Measurement method for optical quantities of non-planar light sources
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IEC 62595-2-5 ®
Edition 1.0 2021-05
INTERNATIONAL
STANDARD
colour
inside
Display lighting unit –
Part 2-5: Measurement method for optical quantities of non-planar light sources
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.120; 31.260 ISBN 978-2-8322-9771-1
– 2 – IEC 62595-2-5:2021 © IEC 2021
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions, abbreviated terms and letter symbols . 9
3.1 Terms and definitions. 9
3.2 Abbreviated terms . 9
3.3 Letter symbols (quantity symbols/unit symbols). 10
4 Measurement devices . 11
4.1 General . 11
4.2 Spot-type light measuring device . 11
4.3 Spectroradiometer (spectral radiance-meter) . 12
4.4 Electrical measurement devices . 12
4.4.1 Current meter . 12
4.4.2 Voltage meter . 13
4.5 Luminous flux measurement devices . 13
4.5.1 General . 13
4.5.2 Luminous flux . 13
4.5.3 Sample stage . 15
5 General measuring conditions . 15
5.1 Standard conditions . 15
5.2 Darkroom conditions . 16
5.3 Measurement setup . 16
5.4 Setting the electrical characteristics of measurement devices . 16
5.4.1 Conditions . 16
5.4.2 Current . 16
5.4.3 Voltage . 16
5.4.4 Power . 16
5.4.5 Warm-up time . 17
6 Optical measurement methods . 17
6.1 General . 17
6.2 Conditions . 17
6.3 Perceptual visual quality . 17
6.3.1 General . 17
6.3.2 Procedures . 17
6.4 Lateral and directional scanning configuration . 18
6.4.1 General . 18
6.4.2 Lateral scanning configuration . 18
6.4.3 Directional scanning configuration . 20
6.5 Depth-of-field and depth-of-focus in measurement . 22
6.5.1 General . 22
6.5.2 Front and rear depth-of-field (DoF) . 22
6.5.3 Front and rear depth-of-focus (dof) . 23
6.6 Measurement procedures. 23
6.6.1 General . 23
6.6.2 Cylindrical LS mounting for lateral measurements . 23
6.6.3 Lateral luminance . 24
6.6.4 Lateral luminance uniformity . 24
6.6.5 Lateral chromaticity and chromaticity variation . 25
6.6.6 Directional luminance . 25
6.6.7 Directional luminance variations . 26
6.6.8 Directional chromaticity and chromaticity variation . 26
6.6.9 Luminous flux . 27
7 Precautions . 30
7.1 Remarks . 30
7.2 Further remarks . 31
7.2.1 General . 31
7.2.2 Report . 31
Annex A (informative) Measurement field on the curved light source . 32
A.1 General . 32
A.2 NPLS curvature and measurement field . 32
A.3 MFs on planar, convex and concave cylindrical LSs . 33
Annex B (informative) Planar light source measurement . 35
B.1 General . 35
B.2 Luminance meter and measurement field . 35
Annex C (informative) Contours of light measurement fields on plane, cylindrical
convex, and concave light sources . 36
C.1 General . 36
C.2 MF contour on a non-tilt and tilt planar DUT . 36
C.3 Projection of an MF contour on the outer surface of a cylindrical DUT . 37
Annex D (informative) LMD aperture and inclination angle on a cylindrical light source . 41
D.1 General . 41
D.2 Inclination angle. 41
D.3 Inclination angle variation . 42
D.4 Depth-of-field . 43
D.5 Measurement field size on the cylindrical light source . 45
Bibliography . 50
Figure 1 – Cartesian and spherical coordinate systems for NPLS measurement . 11
Figure 2 – Example of LMD with the observation area surrounding the measurement field . 12
Figure 3 – Current and voltage measurements using an ammeter between points C and
D and a voltage meter between points A and B . 13
Figure 4 – Geometry of 4π-sphere measurement . 14
Figure 5 – Measuring points on convex and concave DUTs based on the setups of
Figure 4 . 15
Figure 6 – Example of a mirror type goniometric system . 15
Figure 7 – Planar LS and cylindrical LS (NPLS) in lateral scanning measurement
arrangements . 19
Figure 8 – Planar LS and cylindrical LS (NPLS) in a directional scanning arrangement . 21
Figure 9 – Pictorial illustration of depth-of-field, depth-of-focus and circle of confusion
for an LMD . 22
Figure 10 – Rear depth-of-field in the measurement setup of a cylindrical light source . 23
Figure A.1 – Schematic diagram of the optical characteristics measurement of planar,
convex and concave cylindrical light source . 32
– 4 – IEC 62595-2-5:2021 © IEC 2021
Figure C.1 – Geometry of intersections of a cone and a plane in non-tilt and tilt
conditions . 36
Figure C.2 – Expanded plane of a cone and intersection lines with tilt and non-tilt
planes (see Figure C.1) . 37
Figure C.3 – Simulated intersections of three planar light sources with a cone
(measurement field angle, i.e., a solid angle) . 37
Figure C.4 – Geometry for calculating the intersection of a cone (measurement field
angle; solid angle) and a cylinder (light source) . 38
Figure C.5 – Intersection of a cone and a cylindrical DUT . 38
Figure C.6 – Measurement of a convex cylindrical LS and the possible cases, and
illustration of the effect of the measurement field angle cone and the angle of
inclination of the measurement direction . 40
Figure D.1 – Measurement of a cylindrical light source for a non-zero aperture LMD
and fixed measurement field (b) . 41
Figure D.2 – Variation of inclination angle, θ , with D for each cylindrical LS of
D LMD
radius R . 42
Figure D.3 – Variation of rear DoF with D (for measurement field angles of 2°, 1°,
LMD
0,2°, 0,1°) for zero aperture LMD . 43
Figure D.4 – Rear DoF variations with measurement distance D , for light source
LMD
R in Annex A . 45
Figure D.5 – Variation of measurement field with D for cylindrical light sources of
LMD
radii R = 20 mm, 35 mm, 50 mm, and measurement field angles of β = 2°, 1°, 0,2°, 0,1° . 47
Figure D.6 – Difference in variation of MF with D for radii R = 20 mm, 35 mm, 50 mm . 49
LMD
Table 1 – Letter symbols (quantity symbols/unit symbols) . 10
Table B.1 – Example of a measurement result . 35
Table D.1 – Variation of inclination angles with half of the MF size; b/2 . 43
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DISPLAY LIGHTING UNIT –
Part 2-5: Measurement method for optical quantities
of non-planar light sources
FOREWORD
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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.
International Standard IEC 62595-2-5 has been prepared by IEC technical committee 110:
Electronic displays.
The text of this International Standard is based on the following documents:
FDIS Report on voting
110/1296/FDIS 110/1320/RVD
Full information on the voting for the approval of this International Standard can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 62595 series, published under the general title Display lighting unit,
can be found on the IEC website.
– 6 – IEC 62595-2-5:2021 © IEC 2021
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document 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.
INTRODUCTION
The recent introduction of curved OLED TVs, and the expected rapid spread of flexible displays
in portable devices, highlights the necessity of new measurement methods. In recent years
flexible displays have been integrated into products such as cellular phones and wearable
devices [1] to [5] . Development and integration of flexible displays have increased the
application of curved devices, for example distinct or curved-back large-size wall displays,
foldable signage displays, and commercial wearable or handheld devices. The measurement of
optical characteristics of displays with radii larger than 35 mm has been documented.
Recently flexible light sources (LSs) have been used for general lighting applications and as
light source for flexible non-emissive displays. Since bending a planar lighting unit alters the
optical properties of the unit, assessment of the optical performance of the lighting units in a
curved state, i.e., concave or convex condition, is indispensable for manufacturing companies.
A light source can be a planar or non-planar (continuous multiple curvatures), i.e., convex (outer
light emitting surface of a curvature), or concave light source (inner light emitting surface of a
curvature). When a light source is bent the LS is under strain, i.e., tension or depression, the
optical characteristics differ from that of a planar LS. A non-planar LS may have local curvatures
on its surface with different surface normal from position to position. Such an LS can be a
semiconductor light-emitting diode (LED, OLED, polymer LED (PLED)) or a phosphor excited
type using a pump source. An LS can have a narrow-band radiation or more than one narrow
band emission.
Issues concerning flexible light sources with surface curvatures, which are different from those
issues concerning displays (e.g., resolution, contrast, lateral and directional characteristics or
directions of viewing), hitherto have not been documented.
Since the characteristics of a non-planar light source (NPLS) change with the decreasing radius
of the curvature, the optical characteristics of LS such as lateral and directional luminance and
luminance variations, lateral and directional chromaticity distributions and their variations,
luminous intensity distribution, and luminous flux, will be measured and evaluated.
This document establishes the measurement methods for cylindrical light sources that can be
a base for the study of non-planar LS, which is assumed to be an integration of small areas.
The fundamental element of such a surface can be a convex or a concave curvature with a first
order of radius, i.e., a cylindrical shape, which is worth considering in this document.
In addition, a curved light source is used in a variety of conditions. Therefore, the optical
measurements of an LS will be performed in a darkroom.
As in the measurement of planar LSs the following measurements are used for convex and
concave LS measurements: 1) a lateral scanning measurement and 2) a directional scanning
measurement. In the case of lateral scanning, the surface normal coincides with the optical axis
of the light measurement device. In the case of directional scanning the local surface normal
makes an angle with the optical axis of the measurement device.
Since the aperture of a light measurement device is not zero (non-zero aperture), there exist
an optimized measurement distance and angle (i.e., 0,1°, 0,2°, 1°, and 2°) for the
measurements. In the measurement of a cylindrical LS, a light measurement device which has
sufficient depth-of-field or depth-of-focus is selected, because the measurement field on the LS
has a three-dimensional geometry and is different from that of a plane.
____________
Numbers in square brackets refer to the Bibliography.
– 8 – IEC 62595-2-5:2021 © IEC 2021
DISPLAY LIGHTING UNIT –
Part 2-5: Measurement method for optical quantities
of non-planar light sources
1 Scope
This part of IEC 62595 specifies the measurement methods for measuring the optical
characteristics of convex and concave cylindrical light sources. These non-planar light sources
(NPLSs) can have either a continuous, distinct, segmented or block-wised light radiating
surface, for example OLED panels, integrated LEDs, integrated mini-LEDs, micro-LEDs, laser
diodes, each being either monochromatic or polychromatic.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 61747-6-2, Liquid crystal display devices – Part 6-2: Measuring methods for liquid crystal
display modules – Reflective type
IEC 62595-2-1, Display lighting unit – Part 2-1: Electro-optical measuring methods of LED
backlight unit
IEC 62595-2-3, Display lighting unit – Part 2-3: Electro-optical measuring methods for LED
frontlight unit
IEC 62679-3-3, Electronic paper displays – Part 3-3: Optical measuring methods for displays
with integrated lighting units
IEC 62922, Organic light emitting diode (OLED) panels for general lighting – Performance
requirements
ISO/CIE 11664-3, Colorimetry – Part 3: CIE tristimulus values
ISO/CIE 19476, Characterization of the performance of illuminance meters and luminance
meters
CIE S 017/E:2020, International Lighting Vocabulary
CIE 1931, Colour space
3 Terms, definitions, abbreviated terms and letter symbols
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
planar light source
light source with a nearly infinite radius of curvature
3.1.2
non-planar light source
light source having continuous multiple curvatures
3.1.3
convex light source
light source defined by the outer light emitting surface of a curvature
3.1.4
concave light source
light source defined by the inner light emitting surface of a curvature
3.1.5
flexible light source
light source capable of bending or being bent or to endure strain without being destroyed
3.1.6
single-curvature surface emission light source
cylindrical light source
light source that possesses one radius of curvature whether negative (concave) or positive
(convex), along its length, width or diagonal
3.1.7
multiple-curvature surface light source
light source that possesses multiple radii of curvatures whether negative (concave) or positive
(convex), along any dimension such as length, width or diagonal
3.1.8
phosphor converted emission light source
light source with a pump source that is used to excite a phosphor or any phosphor-like material
that radiates light of wavelengths longer than the pump source
3.2 Abbreviated terms
CCT Correlated colour temperature
COC Circle of confusion
DC Direct current
DoF Depth-of-field
dof Depth-of-focus
DUT Device under test
– 10 – IEC 62595-2-5:2021 © IEC 2021
LED Light emitting diode
LMD Light measurement device
LS Light source
MF Masurement field
NPLS Non-planar light source
OLED Organic light emitting diode
PLS Panar light source
SLMD Spot-type light measuring device
NOTE The measurement field is an area on the DUT viewed through the LMD lens within a cone limited by the
measurement field angle.
3.3 Letter symbols (quantity symbols/unit symbols)
The letter symbols for NPLS are shown in Table 1.
Table 1 – Letter symbols (quantity symbols/unit symbols)
Definition Symbol Unit
Luminance of an arbitrary area centred at point (x , y ) on an NPLS L (x , y , θ , φ )
cd/m
i i vi i i 0 0
L
Maximum luminance on an NPLS cd/m
vM
L
Minimum luminance on an NPLS
cd/m
vm
L
Directional average luminance on an NPLS
cd/m
va
L
Centre luminance on NPLS (in case of definition for an NPLS)
cd/m
vc
U
Lateral luminance uniformity %
lat
U
Directional luminance uniformity %
dir
L (x, y, z, θ, φ)
Directional luminance viewed from an arbitrary direction cd/m
v
Chromaticity difference (chromaticity difference, CIE 1976) Δu′v′
Δu ′v′ (θ, φ, x , y , z )
Directional chromaticity difference
i i i
U
Uniformity in chromaticity
c
ΔL
Depth-of-field mm
Depth-of-focus Δl mm
I
Direct current mA
DC
I
Peak value of an alternating current mA
peak
I
RMS of an alternating current mA
rms
I
Effective value of an alternating current mA
eff
V
DC voltage V
DC
V
Peak value of an alternating voltage V
peak
V
RMS of an alternating voltage V
rms
V
Effective value of an alternating voltage V
eff
CCT
Correlated colour temperature for lateral measurement K
lat
CCT
Correlated colour temperature for directional measurement K
dir
Φ
Luminous flux of a standard LS lm
vstd
Φ
Luminous flux of a DUT lm
vDUT
x ,y
Chromaticity coordinates
ca ca
NOTE Directional luminance distribution, L (x , y , θ, φ) , is measured for an area centred at point (x , y , z ), along
vi i i i i i
the zenith angle (θ) and an intended azimuth angle (φ).
4 Measurement devices
4.1 General
In 4.1 to 4.5 a light measurement device, such as a spectrometer, an integrating sphere and a
goniometer with LMD are used. In addition, three axial stages for fixing the device under test
are used.
For an evaluation of the measurement results, the Cartesian and the spherical coordinate
systems are used as shown in Figure 1.
Figure 1 – Cartesian and spherical coordinate systems for NPLS measurement
4.2 Spot-type light measuring device
The spot LMD (SLMD) shall be equipped with a view finder (see Figure 2). The position of the
entrance pupil (aperture) of the LMD shall be provided by the manufacturer or the supplier. The
size of the entrance pupil of the LMD should be set between 2 mm and 5 mm, and shall be
smaller than the output light field of the DUT [1] to [6].
NOTE 1 The terms used in Figure 2 correspond to ISO/CIE 19476.
The optics of an SLMD shall be equivalent to the spectral luminous efficiency function (CIE S
017/E:2020) V(λ). The LMD to measure the optical characteristics such as luminance and
chromaticity shall be calibrated with the appropriate photometric or spectrometric standards.
When a filter-type LMD such as a luminance meter is used to ensure the luminance accuracy
for the intended DUT light sources, its responsivity should comply with the spectral luminous
efficiency for CIE photopic vision or it should be compared with a calibrated spectrometer. The
spectral mismatch correction factor can be specified (see NOTE 2).
NOTE 2 ISO/CIE 19476 indicates the spectral mismatch factor between the spectral responsivity of the filter-type
LMD and the CIE spectral luminous efficiency function. Details of the spectral mismatch correction factor are given
in ISO/CIE 19476.
– 12 – IEC 62595-2-5:2021 © IEC 2021
Figure 2 – Example of LMD with the viewing area
surrounding the measurement field
To ensure accurate measurements, the following requirements shall be applied. Otherwise, the
differences shall be noted in the report. More information on LMD evaluation can be found in
ISO/CIE 19476.
The LMD should be carefully checked before measurements, considering the following points:
– sensitivity of the LMD to measuring light (i.e., to cover the spectrum of the DUT);
– errors caused by the veiling glare and lens flare (i.e. stray light in the optical system);
– timing of data-acquisition, low-pass filtering (noise reduction);
– linearity of detection and data conversion;
– measurement field size.
In addition, the LMD shall be calibrated in accordance with ISO/CIE 19476. All devices shall be
checked for sufficient depth-of-field (DoF). Ensure that the LMD measures the DUT on the
intended curvature area. The depth-of-focus in the LMD’s optical detector, (∆l + ∆l ), is
r f
proportional to the depth-of-field. The depth-of-focus is explained in Annex A.
4.3 Spectroradiometer (spectral radiance-meter)
The wavelength range shall be at least 380 nm to 780 nm and the spectral bandwidth shall be
5 nm or less. The wavelength deviation shall be between -0,3 nm and +0,3 nm. The equipment
shall be calibrated with the spectral radiance standard. The performance should be carefully
checked before measurement, considering the same elements as in 4.2.
4.4 Electrical measurement devices
4.4.1 Current meter
In the measurement of a DUT, a DC drive or signal driving can be required. In case of direct
current, an ammeter (current meter) shall be between points C and D (see IEC 62595-2-1 and
IEC 62595-2-3), as shown in Figure 3.
In case of signal driving of the DUT, the peak value (I ) and effective current (I , i.e., the
peak eff
I value) should be recorded as in Figure 3.
rms
4.4.2 Voltage meter
The measurement of input voltage should be performed under standard measurement
conditions using the voltage meter (voltmeter) between points A and B in as shown in Figure 3
(see IEC 62595-2-1 and IEC 62595-2-3).
In case of DC driving of the DUT, the voltage (V ) should be recorded by using a voltmeter
DC
between A and B in Figure 3.
In case of signal driving of the DUT, the peak value (V ) and effective voltage (V i.e., the
peak eff
V value) should be recorded.
rms
The measurement of input voltage should be performed under standard measurement
conditions using the voltage meter (voltmeter) between points A and B as shown in Figure 3.
Figure 3 – Current and voltage measurements using an ammeter between
points C and D and a voltage meter between points A and B
4.5 Luminous flux measurement devices
4.5.1 General
There are two typical methods of measuring luminous flux:
1) a spherical photometer method with an integrating sphere, and
2) a light distribution measurement method with a goniophotometer of any type for
measurement of the luminous intensity from which the luminous flux is calculated.
4.5.2 Luminous flux
4.5.2.1 Integrating sphere method and installation position
An integrating sphere can perform luminous flux measurement with reasonable accuracy. The
size of an integrating sphere is important in the measurement of a DUT. The larger integrating
sphere exhibits less throughput than the smaller spheres and thus higher optical attenuation,
thereby eventually introducing a lower signal-to-noise ratio. One of the points that shall be
considered is the effect of self-absorption and its correction. This means that the percentage of
flux absorbed by installations and by the DUT itself inside the integrating sphere shall be taken
into account. Therefore, prior to measurement, the self-absorption correction factor shall be
measured (6.6.9.4).
This factor shall be used for correcting the real amount of the luminous flux that is emitted by
the LS (removing the effect of the jigs and the DUT itself). In addition, a standard LS with a
– 14 – IEC 62595-2-5:2021 © IEC 2021
spectrum covering the spectrum of the DUT shall be used to calibrate the integrating sphere as
well.
An integrating sphere (4π geometry) setup can be used for DUT (convex/concave cylindrical LS)
flux measurements. Such an LS shall be installed in a manner that light emitted from any sides
is included in the measured value. Figure 4 shows an example of measurement setup.
Regardless of the planar, convex or concave configurations of the sample, the centre of the
light emitting surface of the sample shall be placed at the centre of the sphere, with the light-
emitting area placed in the upper direction, in accordance with IEC 62922.
NOTE The direction of the light emitting surface in an integrating sphere is an important factor. The measurement
results on “setting the direction of the front surface of the light source” were presented at a CIE meeting [9]. The
direction of the light emitting surface, i.e. up, down, right, left, of a DUT in an integrating sphere affects the
measurement results. Based on the results in the reference, the variations between the measured luminous fluxes
are within 4 %.
a) Planar DUT b) Convex DUT c) Concave DUT
NOTE The DUTs are positioned in the same place as the standard lamp, at the centre of the integrating sphere.
Figure 4 – Geometry of 4π-sphere measurement
4.5.2.2 Goniophotometric measurements
Goniophotometry sometimes with mirror is used for measurement of DUTs (convex/concave
cylindrical LSs) of all sizes as an alternative to integrating sphere photometry. The emitted light
from all directions of the DUT shall be included in the measurement.
In the absence of an integrating sphere of appropriate size relative to the DUT a
goniophotometer shall be used.
In the case of a convex-type DUT, the measurement shall be conducted by aligning the rotation
centre at the vertex of the DUT as shown in Figure 5a). For the concave DUT, the inner intended
area is fixed upward as shown in Figure 5b). The positioning of the DUT in a mirror-type
goniometer is shown in Figure 6. A laser marking device on the goniometer or a separate device
on a tripod is used to align the intended area on the DUT in the horizontal and vertical directions.
This alignment system is a horizontal alignment device, so that the xyz-stage can be used for
adjustment of the DUT after being fixed on the stage.
NOTE For general guidance on the use of goniophotometers, see CIE 084:1989 [8], CIE S 025:2015 [9], and 4.5
and 6.2.
In a measurement of a concave cylindrical LS, the side surfaces of the DUT block the
measurement resulting in a limited measurement field angle (zenith angle θ), so that a primary
study of the measurement is required.
a) b)
Figure 5 – Measuring points on convex and concave DUTs
based on the setups of Figure 4
Figure 6 – Example of a mirror type goniometric system
4.5.3 Sample stage
An orthogonal three-axis stage should be used to adjust the measurement field location of the
DUT (Figure 3). A biaxial goniometer should be used to adjust the DUT surface normal in the
intended direction, i.e., aligning the zenith angle (θ) and azimuth angle (φ) for the DUT (requiring
the axial stage). The positioning of these devices shall be sufficiently stable / repeatable to
make the specified measurement repeatability.
5 General measuring conditions
5.1 Standard conditions
Unless otherwise specified all tests and measurements for an NPLS (e.g. cylindrical LS) shall
be carried out after sufficient warm-up time (see 5.4.5), under the standard environmental
conditions as follows:
– temperature 25 °C ± 3 °C
– relative humidity 25 % to 85 %
– atmospheric pressure 86 kPa to 106 kPa
When different environmental conditions are used, these conditions shall be reported in detail
in the specification.
– 16 – IEC 62595-2-5:2021 © IEC 2021
NOTE See IEC 61747-3-1 [10] , IEC 62679-3-3, and IEC 61747-6-2.
5.2 Darkroom conditions
The optical performance of a light source is initially measured under darkroom conditions. The
illuminance contribution from the background illumination reflected off the room shall be less
than 0,5 % of the minimum illuminance of the light source (when the light source is switched
ON). If the condition is not satisfied, then background subtraction is required, and it shall be
noted in the test report. In addition, if the sensitivity of the LMD is inadequate to measure at the
low level, then the lower limit of the LMD shall be noted in the test report.
Unless stated otherwise the standard lighting conditions shall be the darkroom conditions.
5.3 Measurement setup
The DUT, LMD, power source, driving and control devices for the DUT, and the electrical
measuring devices should be arranged as shown in Figure 3. The luminance of the DUT shall
be measured using an SLMD.
5.4 Setting the electrical characteristics of measurement devices
5.4.1 Conditions
Electro-optical measurements and visual inspection shall be carried out under the standard
environmental conditions given in 5.1. When different environmental conditions are used, they
shall be noted in the visual inspection or test report.
5.4.2 Current
The measurement of input current should be performed under standard measurement
conditions using the ammeter between points C and D in Figure 3. In case of DC driving of the
DUT, the current (I ) should be recorded by using an ammeter between C and D in Figure 3.
DC
In case of signal driving of the DUT, the peak value (I ) and effective current (I , i.e., the
peak eff
) should be recorded.
value I
rms
5.4.3 Voltage
The measurement of input voltage should be performed under standard measurement
conditions using the voltage meter (voltmeter) between points A and B in Figure 3
(IEC 62595-2-1 and IEC 62595-2-3).
In case of DC driving of the DUT, the voltage (V ) should be recorded by using a voltmeter
DC
between points A and B in Figure 3.
In case of signal driving of the DUT, the peak value (V ) and effective voltage (V i.e., the
peak eff
V value) should be recorded.
rms
The measurement of input voltage should be performed under standard measurement
conditions using the voltmeter between points of A and B shown in Figure 3.
5.4.4 Power
The measurement of supplied power consumption should be carried out under the standard
measurement conditions given in 5.4 (see IEC 62595-2-1), using a power meter in case of DC
driving (V × I ). However, in case of signal driving, the supplied power should be calculated
DC DC
as V × I or V × I . The measurement of power consumption should be carried out under
eff eff rms rms
the standard measurement conditions given in 6.1 and 6.2 (IEC 62595-2-1), using a power
meter.
5.4.5 Warm-up time
The measurement of a DUT shall be performed with the DUT in steady state. The warm-up time
differs for various devices. F
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