SIST EN 61947-1:2003

SLOVENSKI SIST EN 61947-1:2003

STANDARD
oktober 2003
Electronic projection - Measurement and documentation of key performance
criteria - Part 1: Fixed resolution projectors (IEC 61947-1:2002)
ICS 33.160.99; 37.040.10 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

EUROPEAN STANDARD EN 61947-1
NORME EUROPÉENNE
EUROPÄISCHE NORM November 2002

ICS 37.020; 35.180; 33.160.60
English version
Electronic projection -
Measurement and documentation of key performance criteria
Part 1: Fixed resolution projectors
(IEC 61947-1:2002)
Projection électronique -  Elektronische Projektion -
Mesure et documentation des critères Messung und Dokumentation wichtiger
principaux de performance Leistungsmerkmale
Partie 1: Projecteurs à résolution fixe Teil 1: Projektoren fester Auflösung
(CEI 61947-1:2002) (IEC 61947-1:2002)

This European Standard was approved by CENELEC on 2002-10-01. CENELEC members are bound to
comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and
notified to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta,
Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2002 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61947-1:2002 E
Foreword
The text of document 100/501/FDIS, future edition 1 of IEC 61947-1, prepared by IEC TC 100, Audio,
video and multimedia systems and equipment, was submitted to the IEC-CENELEC parallel vote and
was approved by CENELEC as EN 61947-1 on 2002-10-01.
The following dates were fixed:

– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2003-07-01

– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2005-10-01

Annexes designated "normative" are part of the body of the standard.
Annexes designated "informative" are given for information only.
In this standard, annexes A, B, D and ZA are normative and annexes C, E, F, G, H and I are
informative.
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61947-1:2002 was approved by CENELEC as a European
Standard without any modification.
__________
- 3 - EN 61947-1:2002
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of any
of these publications apply to this European Standard only when incorporated in it by amendment or
revision. For undated references the latest edition of the publication referred to applies (including
amendments).
NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
1) 2)
IEC 61947-2 - Electronic projection - Measurement EN 61947-2 2002
and documentation of key performance
criteria
Part 2: Variable resolution projectors

1) 2)
IEC 61966-4 - Multimedia systems and equipment - EN 61966-4 2000
Colour measurement and management
Part 4: Equipment using liquid crystal
display panels
1) 2)
IEC 61966-5 - Part 5: Equipment using plasma display EN 61966-5 2001
panels
1) 2)
ISO 3741 - Acoustics - Determination of sound EN ISO 3741 1999
power levels of noise sources using
sound pressure - Precision methods for
reverberation rooms
1) 2)
ISO 7779 - Acoustics EN ISO 7779 2001
Measurement of airborne noise emitted
by information technology and
telecommunications equipment
1)
Undated reference.
2)
Valid edition at date of issue.

INTERNATIONAL IEC
STANDARD
61947-1
First edition
2002-08
Electronic projection –
Measurement and documentation
of key performance criteria –
Part 1:
Fixed resolution projectors
 IEC 2002  Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch  Web: www.iec.ch
PRICE CODE
Commission Electrotechnique Internationale
V
International Electrotechnical Commission
Международная Электротехническая Комиссия
For price, see current catalogue

– 2 – 61947-1  IEC:2002(E)
CONTENTS
FOREWORD . 3
INTRODUCTION .4
1 Scope . 5
2 Normative references. 5
3 Definitions. 6
4 General requirements.10
5 Light output measurement and specification .11
5.1 Light output specifications.12
5.2 Light output uniformity.13
5.3 Contrast ratio.13
5.4 Light transmission for fixed resolution projection systems: liquid-crystal
imaging devices (LCD) used with an overhead projector (OHP) .13
5.5 Small area contrast ratio for alternating black and white pixel lines .14
6 Fixed resolution projectors characteristics .15
6.1 Displayable format (IEC resolution) .15
6.2 Aspect ratio .15
6.3 Viewing angle (half/gain) specification for devices with an integral screen.15
6.4 Input signal format compatibility .16
6.5 Response time.16
6.6 Colour measurements .16
6.7 Number of colours .17
6.8 Keystone correction .17
7 Range of focus and image size.17
8 Audio characteristics.18
9 Light source specification.18
10 Maximum acoustical noise level .18
11 Power consumption.18
12 Weight .18
13 Dimensions.19
14 Sync hierarchy – Recommended practice .19
Annex A (normative) Figures .20
Annex B (normative) Pattern generator specifications .23
Annex C (informative) Considerations in formulating this standard .24
Annex D (normative) Complete sample specification.26
Annex E (informative) Conversion equations.27
Annex F (informative) Possible causes of photometric measurement errors .28
Annex G (informative) Photometer precision and veiling glare .29
Annex H (informative) Light measuring devices.31
Annex I (Informative) Figure of merit for projection display colour gamut .32
Bibliography .34

61947-1  IEC:2002(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRONIC PROJECTION –
MEASUREMENT AND DOCUMENTATION OF
KEY PERFORMANCE CRITERIA
Part 1: Fixed resolution projectors
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61947-1 was prepared by IEC technical committee 100: Audio,
video and multimedia systems and equipment.
The text of this standard is based on the following documents:
FDIS Report on voting
100/501/FDIS 100/537/RVD
Full information on the voting for the approval of this standard 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.
The committee has decided that the contents of this publication will remain unchanged until
2004. At that date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
– 4 – 61947-1  IEC:2002(E)
INTRODUCTION
This standard was developed to ensure a common, meaningful description of key performance
parameters for fixed resolution projectors. The measurement methods and test signals
correlate closely to typical uses involving computer-generated text and graphics displays.
These measurements evaluate the actual viewable image that emanates from fixed resolution
projectors. The resulting performance specifications are conservative in nature and allow any
display device to be used beyond its rated specifications with degraded performance. The point
at which this degraded performance is no longer useful is highly subjective and strongly
affected by the environment and the application.
This standard is designed to specify a means of measuring and quantifying the performance
of fixed resolution projectors and is not intended to provide design goals for manufacturers of
such equipment.
61947-1  IEC:2002(E) – 5 –
ELECTRONIC PROJECTION –
MEASUREMENT AND DOCUMENTATION OF
KEY PERFORMANCE CRITERIA
Part 1: Fixed resolution projectors
1 Scope
This part of IEC 61947 specifies requirements for measuring and documenting key
performance parameters for electronic projection systems with fixed resolution projectors in
which the light source and projection/magnification optics are an integral part of the system
(i.e. individual pixel light sources or matrix displays such as liquid crystal, DMD, plasma, or
electroluminescent panels). It also applies to LCD panels or other fixed resolution imaging
devices themselves that are used with overhead projectors.
The provisions of this standard are designed to codify the measurement of the performance of
variable resolution projectors and are not intended to provide design goals for manufacturers of
such equipment.
This standard is intended for fixed resolution projectors that are primarily designed for use with
discrete colour (RGB) raster-scanned video, text, and graphics signals generated by computer
equipment.
NOTE These devices may also accept composite or component television video signals encoded in ITU/R
publications, which are not within the scope of this standard. In this standard, all of these signals are referred to as
television video (TV video).
Projectors and projection systems with multiple variable resolutions, such as cathode-ray tubes
and laser projectors, are not fully addressed by this standard, and reference should be made to
IEC 61947-2.
A discussion of considerations taken into account in the development of this standard appears
in Annex C.
2 Normative references
The following referenced documents are indispensable for the application 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 61947-2, Electronic projection – Measurement and documentation of key performance
criteria – Part 2: Variable resolution projectors
IEC 61966-4, Multimedia systems and equipment – Colour measurement and management –
Part 4: Equipment using liquid crystal display panels
IEC 61966-5, Multimedia systems and equipment – Colour measurement and management –
Part 5: Equipment using plasma display panels
ISO 3741, Acoustics – Determination of sound power levels of noise sources using sound
pressure – Precision methods for reverberation rooms
ISO 7779, Acoustics – Measurement of airborne noise emitted by information technology and
telecommunication equipment
– 6 – 61947-1  IEC:2002(E)
3 Definitions
For the purposes of this standard, the following definitions apply.
3.1
active matrix display
display that uses switches at each pixel to select those pixels to which a voltage will be applied
3.2
active viewing area
horizontal and vertical dimensions in millimetres (inches) of the boundary of the array of pixels.
It may also be expressed in square millimetres or square inches
3.3
aperture ratio (fill factor)
light transmitting/reflecting area of a pixel times the number of pixels divided by the active
viewing area (light transmitting area and light blocking area)
3.4
aspect ratio
proportions of a projected picture area, for example, the width compared to the height
NOTE It is usually expressed in standard ratios such as 4:3, 16:9, or others.
3.5
blanking
process of the beam turning off (blanking) which occurs during horizontal and vertical retrace
(flyback)
3.6
CIE
Commission Internationale de l’Eclairage, the international commission on illumination
NOTE The CIE is an organization devoted to international cooperation and exchange of information among its
member countries on all matters relating to the art and science of lighting.
3.7
CIE chromaticity values
Cartesian coordinates used to define a colour in CIE colour space
NOTE The 1931 chromaticity values are designated x and y. In 1976, the CIE defined a more uniform colour
space. The 1976 CIE chromaticity values are u′ and v′.
3.8
colour mapping
means for accurately displaying colour signals or altering sets of colour signals in a controlled
manner
3.9
contrast ratio
luminance or illuminance ratio of a light area of the image to the dark area of the same image
3.10
correlated colour temperature (CCT) of the white-point
temperature, in kelvins, of the black-body radiator the chromaticity of which is closest to the
chromaticity of a particular light, for example, from a display screen, as measured in the 1960
CIE (u, v) uniform chromaticity space
NOTE An algorithm for computing CCT of the white-point, either from 1931 CIE (x, y) coordinates or from 1960
(u,v) coordinates, appears in Wyszecki and Stiles [1]. A graphical nomogram also appears in this work.

61947-1  IEC:2002(E) – 7 –
Alternatively, a successful numerical approximation has been derived by C. S. McCamy [2]. Given CIE 1931
3 2
coordinates (x, y), McCamy's approximation is CCT = 437 n + 3601 n + 6831 n + 5517 where
n = (x - 0,3320)/(0,1858 - y). This approximation, the second of three proposed, is close enough for any practical
use between 2000 K and 10 000 K. In units of 1960 u, v chromaticity, it is agreed that the concept of CCT of the
white-point has little meaning beyond the distance of 0,01 from the Planckian locus (see Robinson et al [3]), where
the distance is specified by:
2 2
Δuv = (u - u ) + (v - v )
1 2 1 2
Most commercial colorimeters will report CCT of the white-point from 0,0175 u, v units above the Planckian locus to
0,014 u,v units below this locus.
3.11
digital micromirror device (DMD)
semiconductor light micromirror array. The DMD can switch incident light on or off in discrete
pixels within microseconds to produce projection display systems
3.12
optical distortion
situation in which an image is not a true-to-scale reproduction of an object due to the optics of
the system
NOTE There are many types of distortion, such as anamorphic, barrel, curvilinear, geometric, keystone,
panoramic, perspective, radial, stereoscopic, tangential, and wide-angle.
3.13
f/number
stop number
the reciprocal value of the relative aperture
NOTE Relative aperture of a photographic lens: twice the numerical aperture where the numerical aperture is the
sine of the semi-angle subtended by the exit pupil at the focal plane. For photographic applications, the aperture is
equivalent (within a 1/3 stop) to the ratio of the diameter of the entrance pupil to the focal length. (See ISO 517:
1996(E) Photography – Apertures and related properties pertaining to photographic lenses – Designations and
measurements.)
3.14
fall time
time, in milliseconds, for the image brightness to change from 90 % of its maximum value to
10 % of its maximum value
3.15
focal length
distance between the centre of the focusing lens or mirror and the focal spot.
NOTE Shorter focal length projection lenses produce larger screen images for a given distance from the screen
3.16
focus
adjustment of an optical system to achieve the greatest possible sharpness
3.17
four corners
centres of the four corner points (see Figure A.2), located at 10 % of the distance from the
corners to the centre of point 5
3.18
front screen projection
image projected on the audience side of a light-reflecting screen

– 8 – 61947-1  IEC:2002(E)
3.19
illuminance
quotient of a luminous flux incident on an element of the surface containing the point by the
area of that element
Unit: lux (lx)
3.20
light source life expectancy
time that the light source can keep its projected light output as measured in this standard,
higher than 50 % of the initial value when tested with a duty cycle of 2 h on and 15 min off
3.21
liquid-crystal display (LCD)
display made of material the reflectance or transmittance of which changes when an electric
field is applied
3.22
luminance
L
luminance in a given direction is the luminous intensity per unit of projected area of any
surface, as viewed for that direction
Unit: candela per square metre (cd/m²).
3.23
luminous flux
quantity derived from radiant flux by evaluating the radiation according to its action upon a
selective receptor, the spectral sensitivity of which is defined by the standard 1931 CIE spectral
luminance efficiency function for the photopic V(λ) function
NOTE Quantity of light expressed in lumens, and directed in a given direction.
3.24
luminous intensity
luminous flux per unit solid angle emitted or reflected from a point source
Unit: candela
3.25
object
slide or transmissive/reflective image forming panel, such as an LCD, that is illuminated and
imaged by the optics onto a viewing screen
3.26
peak angle
angle at which maximum luminance is observed
3.27
photometric units
units of light measurement based on the response of the average human observer. The
response of the average human observer is defined by the 1931 CIE spectral luminance
efficiency function for the photopic V(λ) function
3.28
pixel
smallest element of a display space that can be independently assigned a colour or intensity

61947-1  IEC:2002(E) – 9 –
3.29
projection distance
distance between the projector and the screen measured in linear units (i.e. metres, feet, or
inches). This distance is considered to be the distance from the image displayed on the screen
to the outermost element of the projection lens
3.30
rear screen projection
image projected through a light transmitting screen to the audience side of the screen
3.31
response time
sum of the rise and fall times divided by 2. It is measured at (23 ± 5) °C ambient temperature
after 15 min in operation:
t + t
r f
t =
res
3.32
rise time
time, in milliseconds, for the image brightness to change from 10 % of its maximum value to
90 % of its maximum value
3.33
Scan rate
3.33.1
vertical scanning
rate (hertz) at which one complete image (frame) is drawn
3.33.2
horizontal scanning
rate (kilohertz) at which each line of the display is scanned
3.34
screen gain
measure of the projector screen luminance as compared to the luminance of a block of a
perfect reflecting diffuser, (preferably a calibrated tablet of pressed barium sulfate, as specified
in CIE 38: 1977, Section 12.2.5 or pressed polytetrafluoroethylene (PTFE) powder, see CIE
135/6: 1999) illuminated with the same projection source, which serves as the standard for a
gain of 1,0
NOTE Gains are typically measured perpendicular to the centre of the screen.
3.35
standard viewing position
for display devices the screen of which is an integral part of the projection device, the standard
viewing position is the reference position for measurements, and is specified by the standard
viewing distance measured from the horizontal plane on which the display under test is placed
3.36
steradian
Sl unit of solid angle: solid angle that, having its vertex at the centre of a sphere, cuts off an
area of the surface of the sphere equal to that of a square with sides of length equal to the
radius of the sphere
[IEV 845-01-20 (ISO 31/1-2.1,1978)]

– 10 – 61947-1  IEC:2002(E)
3.37
transmission
measure of the amount of light that is transmitted by an optical medium relative to the total
amount of incident light
3.38
vertical lines
number of active lines in a picture
3.39
viewing angle/half gain
angle between the direction of maximal reflection and the direction where the luminance drops
to 50 % of its value
NOTE This quantity should be measured in the centre of the viewing screen.
3.40
visible light
electromagnetic radiation to which the human observer is sensitive through the visual
sensations that arise from the stimulation of the retina of the eye
NOTE The spectral range is typically considered to have a range of 380 nm to 780 nm (3 800 Å to 7 800 Å).
3.41
zoom lens
focusing lens that has a second, primary adjustment for focal length
NOTE This capability allows smaller or larger image sizes from a fixed projection distance. The zoom ratio is
typically stated in a range of screen width/projection distance ratios, for example a 1:2 to 1:4 zoom lens could focus
a 10 m or a 5 m wide image from a 20 m throw distance.
4 General requirements
This part of IEC 61947 is intended to specify a complete description of the product. In
accordance with these intentions, a complete specification (see example in Annex D) shall be
used in product descriptions. If a particular specified measurement was not performed, the
complete specification shall include the text “not measured” or “data not available” under that
measurement section.
NOTE The use of partial specifications in product descriptions is not recommended since many of the specified
measurements are interrelated (e.g. resolution and light output).
All measurements and specifications shall conform to the following:
• the measurements of light output, visual resolution, and blanking found in this standard are
interrelated and shall be measured and specified as a set;
• the parameters and measurement criteria specified in this document allow for a wide variety
of equipment performance. Secondary, non-conforming specifications are permitted to
allow flexibility for special features of various products and technologies, but shall be
displayed in the same type face font and density at least 25 % smaller in size;
• a sample from normal production runs shall be used to establish the specifications. Results
from measurements of pre-production and prototype units shall be identified as preliminary
specifications;
• the sample units shall not be adjusted or enhanced beyond normal production parameters,
especially in a way that would reduce the normal operating life of any component or of the
entire display;
• all optical, electrical focus, and convergence controls shall be adjusted for the sharpest
display over the largest possible percentage of the illuminated area, using appropriate
patterns from an internal or external test generator as needed;

61947-1  IEC:2002(E) – 11 –
• the equipment shall be allowed to stabilize without further adjustment for a minimum
of 15 min, at a nominal ambient room temperature of (23 ± 5) °C, before taking
measurements;
NOTE Measurement could also be taken after 1 h of operation with all covers in place, white raster, as
intended for normal use.
• measurements shall take place in a lightproof room where the only source of illumination is
the projector. Less than 1 % of the light on the screen shall be from any source other than
the projector. The projector should be operated with all covers in place as in normal
operation;
• for contrast ratio measurement, less than 10 % of the light on the screen where a black
image is projected shall be from any source other than the projector;
• the display device shall be adjusted for a 4:3 (horizontal:vertical) aspect ratio, if it is
capable of it. The horizontal and vertical size of the scanned area shall be adjusted to
the maximum usable diagonal size of the light modulator or source, such as a light valve
or CRT, with the specified aspect ratio;
• displays designed for only one aspect ratio shall be adjusted to, and measured at, the
design aspect ratio that shall be specified with the light output;
• devices that use a separate screen shall be positioned relative to the screen in accordance
with the angle, height, and distance specified in the manufacturer’s set-up instructions;
• displays with integral screens shall be adjusted so as exactly to fill their viewing screens.
The displays shall not delete nor hide any data in the corners or edges in the horizontal
dimension. The vertical dimension shall then be adjusted to achieve a 4 H:3 V aspect ratio,
if applicable;
• all measurements shall be taken with no adjustments made between measurements;
• measurements shall be specified in international units, or both international and national
units, with international units listed first.
5 Light output measurement and specification
The light output specification shall be stated in lumens for projectors with separate screens,

and in candela per square metre (nits) for displays with self-contained screens.
The following conditions shall be met:
• input signals shall be supplied by a standard test signal source, as specified in Annex B;
• the light meter shall be photopically and cosine corrected, calibrated, and traceable to a
national standard;
• a special test pattern (see Figure A.1) shall be used to set the controls for making
measurements. The black level (or brightness control) shall be set to the point where the
maximum number of signal level blocks on the top line, representing 0 %, 5 %, 10 % and
15 % signal levels, are visible and distinct from the adjacent signal level blocks.
The video gain (contrast or picture control) shall be advanced from minimum until the
maximum number of signal level blocks in the lower line of the pattern, representing the 85 %,
90 %, 95 %, and 100 % signal levels, are visible and distinct from the adjacent signal level
blocks, or until the picture no longer increases in brightness as limited by automatic brightness
circuitry.
In the event of controls interacting, they shall be readjusted in sequence in order to achieve the
described conditions on the screen. The controls shall remain at these settings for all
measurements. The total number of signal level blocks distinguishable in this pattern shall be
stated in the specification.
A 100 % full-white image shall be used for the correlated colour temperature (CCT) and screen
illuminance measurements.
– 12 – 61947-1  IEC:2002(E)
For display devices where the screen is not an integral part of the viewing system, the CCT
shall be measured by placing a cosine corrected colorimeter in the plane of the focused image.
For display devices the screen of which is an integral part of the projection device, the CCT
shall be measured by focusing a colorimeter at the centre of the screen. The measurement
field shall be at least 3 pixels by 3 pixels. The projection system shall be adjusted until the
desired CCT is obtained.
The equipment shall be stabilized without further adjustment for at least 15 min before making
any colour or other measurement. All measurements shall be made in a darkened room.
Light from the projector shall be measured with a photopically corrected, cosine corrected light-
meter, the calibration of which is traceable to a national standard.
NOTE Meters may suffer from errors due to such problems as spectral mismatch of tristimulus filters. Also,
scanning or pulsed source displays may saturate the meter. For diagnostics, solutions, and further information
concerning light meters, see Annex H.
For display devices where the screen is not an integral part of the viewing system, the screen
illuminance shall be measured with a light meter, the sensor of which is placed in and parallel
to the plane of the focused image at the centre of each of nine equal rectangles and four
corners (see Figure A.2) or the detector can be placed at the viewing space design centre.
The measurement field shall be at least 3 pixels by 3 pixels. The average of the nine readings

in lux (lumens per square metre) shall be multiplied by the number of square metres covered
by the image at the plane of the meter readings. The result shall be taken as the light output of
the projector, in lumens.
The light output specification shall also state the aspect ratio of the display, horizontal and
vertical scan rates, CCT and the lens throw distance ratio and type.
For display devices where the screen is an integral part of the projection device, the luminance
of the screen is measured in candela per square metre (nits) at the centre of each of the nine
equal rectangles (see Figure A.2) or the detector can be placed at the designed viewing
distance.
The standard viewing distance shall be four times the screen height and the standard viewing
angle shall be selected as the peak angle in order to obtain the maximum luminance of the
white picture at the centre of the screen.
Luminance shall be measured for nine zones. The measurements shall be made and specified
at the maximum horizontal and minimum vertical rate, and the minimum horizontal and
maximum vertical rate within the capability of the equipment. The measurement field shall be at
least 3 pixels by 3 pixels. An average of the nine readings shall be taken in order to calculate
the light output specification, in candela per square metre (nits).
5.1 Light output specifications
5.1.1 Light output specification for projectors with a separate screen
EXAMPLE
Light output measurement conditions: 6 500 K CCT, 4:3 aspect ratio, and a 2:1 HD6 lens;
• 180 lm at 15,75 kHz horizontal and 90 Hz vertical;
• 220 lm at 36 kHz horizontal and 40 Hz vertical.

61947-1  IEC:2002(E) – 13 –
5.1.2 Full black light level specification
Measurements shall be made at the same signal as the black rectangles for contrast ratio
measurement (see Figure A.3).
EXAMPLE
• Full black light level: 1,2 lm at 15,75 kHz horizontal and 90 Hz vertical.
5.1.3 Luminance specification for devices with an integral screen
EXAMPLE
Luminance measurement conditions: 9 300 K CCT, 4:3 aspect ratio, and a total screen viewing
angle of 60° horizontal, 20° vertical (higher luminance values are better):
• 27 cd/m² (nits) at 15,75 kHz horizontal and 70 Hz vertical;
• 31 cd/m² at 33 kHz horizontal and 57 Hz vertical.
NOTE Direct comparisons can be made between displays with and without integral screens using candela per
square metre, if both screens have the same horizontal and vertical angles of view. If this is not the case,
mathematical conversions may be made, but will result in unreliable data of questionable value.
5.2 Light output uniformity
The average of nine readings used in the light output measurement shall be taken as the
reference for the light output uniformity measurement. An additional four points, as in
Figure A.2, shall be measured, with the maximum deviation of the resulting 13 measurements
stated as a percentage as in the following example. The measuring field shall be at least
3 pixels by 3 pixels.
NOTE See Annex C for further information on light output measurement.
EXAMPLE
• Brightest measurement locations: 10 % greater than the average;
• Dimmest measurement locations: 5 % less than the average.
5.3 Contrast ratio
The contrast ratio shall be determined from illuminance values, or luminance for devices with
an integral screen, obtained from a black-and-white “chessboard” pattern consisting of sixteen
equal rectangles (see Figure A.3). The white rectangles shall be at full specified light output, as
previously measured, with all controls at the same settings.
Illuminance measurements in lux (candela per square metre with internal screen units) shall be
made at the centre of each of the bright (white) rectangles and the dark (black) rectangles. The
average illuminance or luminance value of the bright rectangles shall be divided by the average
illuminance or luminance value of the dark rectangles. The contrast ratio shall then be
expressed as this ratio:1 (e.g. bright rectangles with an average value of 15 lx and dark
rectangles with an average value of 0,10 lx provide a contrast ratio of 150:1).
5.4 Light transmission for fixed resolution projection systems: liquid-crystal imaging
devices (LCD) used with an overhead projector (OHP)
Light transmission is the percentage of the light transmitted by the LCD. The light output of the
projection system shall be measured in lumens.
The LCD shall be removed from the OHP and replaced with a test mask that is opaque except
for an area equal to the active viewing area of the LCD. It shall be positioned at the same

– 14 – 61947-1  IEC:2002(E)
height above the OHP as was the plane of the LCD pixels, so that the test pattern is placed at
the same viewing screen location and area.
Light transmission shall be expressed as the ratio of two measurements of the luminous flux;
one with the imaging device (LCD) and one with the imaging device replaced by the test mask.
(100 % full white image):
L×100
T =
F
where
T is the light transmission;
L is the luminous flux with LCD;
F is the luminous flux without LCD.
The type of the light source shall also be stated with the results.
EXAMPLE
Light transmission: 5 % with metal-halide OHP, 6 500 K.
5.5 Small area contrast ratio for alternating black and white pixel lines
The small area contrast ratio is a measure of the capability of the projection system to
reproduce fine detail on the screen. This can be compromised by many mechanisms; the
bandwidth of the analogue signal electronics, the driver circuitry for the display cell, and the
optical quality of the projection optics.
Both vertical and horizontal patterns (as illustrated in Figures A.4 and A.5 respectively) shall be
measured. For each measurement, the light sensor array shall be perpendicular to the parallel
lines being measured. The ratio of the light and dark lines (L /L ) is the small area contrast
on off
ratio (SACR):
L
on
SACR=
L
off
Measure the average light output (L and L ) of at least 5 line pairs at the screen centre and
on off
at each of the four corners of the display, and calculate the SACR for both vertical and
horizontal lines. Report the SACR of the corner where the performance is worst.
For display devices where the screen is not an integral part of the viewing system, set up the
vertical and horizontal patterns on the screen, and adjust the distance between the screen and
the detector so that at least 5 detector pixels fall within each pixel line imaged on the screen.
At least 5 white and 5 black lines (5 line pairs) falling on the screen shall be imaged onto the
detector. Measure the average of the white and black lines (L :L ) and report the SACR of
on off
the centre.
Move the detector to each of the corners and repeat the measurements for all four corners.
Report the contrast ratio of the corner where the performance is worst.
The horizontal small area contrast ratio shall be obtained by measuring the vertical parallel
lines. The vertical small area contrast ratio shall be obtained by measuring the horizontal
parallel lines.
61947-1  IEC:2002(E) – 15 –
EXAMPLE
Small-area contrast ratio:
Vertical pattern – centre 10:1
Vertical pattern – corner 8:1
Horizontal pattern – centre 4.5:1
Horizontal pattern – corner 5:1
6 Fixed resolution projectors characteristics
6.1 Displayable format (IEC resolution)
The displayable format describes the physical array of picture elements that is imaged onto the
screen in terms of:
• the number of overlaid partial images, for example “three panel overlaid”, “single panel”,
etc.;
• the width of the picture in units of the picture element width;
• the number of horizontal “rows” of picture elements;
• the picture element pattern, expressed as:
1) the position of bordering picture elements in adjacent rows relative to each other as
described by:
orthogonal array: a format in which the centres of the picture elements in adjacent lines
are on a straight line in a direction perpendicular to the direction of the row;
staggered array: a format in which the centres of the picture elements in odd and even
rows do not form an orthogonal array; that is, every other row is displaced sideways by
some fraction of the width of a picture element with respect to the other rows;
2) the colour capability of the picture elements per superimposed partial image as
described by:
sequential colour: an orthogonal or staggered type panel with colours superimposed
through a common aperture in serial time.
EXAMPLES
• single panel, 640 × 480, stripe colour;
• single panel, 1068 × 480, staggered array;
• three panel overlaid, 644 × 484, orthogonal array;
• three panel overlaid, 1068 × 480, staggered array;
• 640 × 480 monochrome;
• single panel, 640 × 480, orthogonal array, sequential colour.
6.2 Aspect ratio
The aspect ratio of a display can be described as follows:
for 640 × 480 resolution and a square pixel (1:1), the aspect ratio is 1.33:1 (4:3).
6.3 Viewing angle (half/gain) specification for devices with an integral screen
This is the angle between the normal or peak angle perpendicular to the centre of the viewing
screen and the observer in the horizontal (left and right) and vertical (up and down) direction
where the intensity of luminance drops to 50 % of its value, for example, total screen viewing
angle of 60° horizontal and 20° vertical (full angle at 1/2 intensity).

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6.4 Input signal format compatibility
Manufacturers shall supply customers with a list of compatible modes, video standards and, if
necessary, hardware description.
If input signals formats are different from the displayable format acceptable by the projector,
the method of converting the input signal format to the displayable format shall be specified, for
example, scaling down the input EWS format to displayable XGA format.
6.5 Response time
The response time shall be specified by the light valve manufacturer, for example, less than
50 ms for the LCD light valve.
6.6 Colour measurements
6.6.1 General
Colour measurements shall be made either:
a) in accordance with IEC 61966-4 or IEC 61966-5, as appropriate according to the type of
projection device; or
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