IEC 61947-2:2001
(Main)Electronic projection - Measurement and documentation of key performance criteria - Part 2: Variable resolution projectors
Electronic projection - Measurement and documentation of key performance criteria - Part 2: Variable resolution projectors
IEC 61947-2:2001 specifies requirements for measuring and documenting key performance parameters for CRT and laser-based projectors and other variable resolution projectors that are capable of multiple variable resolutions and in which the image is raster-scanned. This bilingual version (2013-02) corresponds to the monolingual English version, published in 2001-09.
Projection électronique - Mesure et documentation des critères principaux de performance - Partie 2: Projecteurs à résolution variable
La CEI 61947-2:2001 spécifie les exigences concernant la mesure et la documentation des paramètres principaux de performance pour les tubes cathodiques et les projecteurs à laser et autres projecteurs à résolution variable qui ont la capacité d'avoir plusieurs résolutions variables et dans lesquels l'image est obtenue par balayage de trame. La présente version bilingue (2013-02) correspond à la version anglaise monolingue publiée en 2001-09.
General Information
Standards Content (Sample)
INTERNATIONAL IEC
STANDARD
61947-2
First edition
2001-09
Electronic projection –
Measurement and documentation
of key performance criteria –
Part 2:
Variable resolution projectors
Reference number
Publication numbering
As from 1 January 1997 all IEC publications are issued with a designation in the
60000 series. For example, IEC 34-1 is now referred to as IEC 60034-1.
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edition numbers 1.0, 1.1 and 1.2 refer, respectively, to the base publication, the
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INTERNATIONAL IEC
STANDARD
61947-2
First edition
2001-09
Electronic projection –
Measurement and documentation
of key performance criteria –
Part 2:
Variable resolution projectors
IEC 2001 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 Geneva, Switzerland
Telefax: +41 22 919 0300 e-mail: inmail@iec.ch IEC web site http://www.iec.ch
Commission Electrotechnique Internationale
PRICE CODE
X
International Electrotechnical Commission
For price, see current catalogue
– 2 – 61947-2 IEC:2001(E)
CONTENTS
FOREWORD . 4
INTRODUCTION .6
1 Scope . 7
2 Normative references . 7
3 Definitions. 8
4 General requirements. 12
5 Light output measurement and specification . 13
5.1 Light output specifications . 14
5.1.1 Light output specification for projectors with a separate screen . 14
5.1.2 Full-black light level specification. 15
5.1.3 Luminance specification for devices with an integral screen . 15
5.2 Light output uniformity. 15
5.2.1 Example of a uniformity specification. 15
5.3 Contrast ratio . 15
5.4 Blanking measurement and specification . 15
5.5 Effective blanking time . 16
5.6 Blanking specification. 16
6 Variable resolution projector characteristics. 17
6.1 Visual resolution measurement and specification. 17
6.1.1 Description and general requirements. 17
6.1.2 Horizontal resolution. 17
6.1.3 Vertical resolution . 18
6.1.4 Procedure . 18
6.2 Video frequency response specifications . 20
6.2.1 Frequency response specifications . 20
6.3 Viewing angle (half/gain) specification for devices with an integral screen. 20
6.4 Input signal format compatibility . 20
6.5 Response time . 20
6.6 Colour measurements . 21
6.6.1 Colour chromaticity. 21
6.6.2 Colour uniformity. 21
6.7 Keystone correction . 22
7 Range of focus and image size. 22
8 Audio characteristics . 22
9 Light source specification . 22
10 Noise: maximum sound level . 23
11 Power consumption. 23
12 Weight . 23
13 Dimensions .23
14 Recommended practices . 23
14.1 Recommended practice 1 − Sync hierarchy . 23
14.2 Recommended practice 2 − DC restoration. 23
14.3 Recommended practice 3 − Sync . 24
14.4 Recommended practice 4 − Scan range labelling. 24
61947-2 IEC:2001(E) – 3 –
Annex A (normative) Figures . 25
Annex B (normative) Pattern generator specifications . 29
Annex C (informative) Considerations in formulating this standard . 30
C.1 General. 30
C.2 Light output measurement . 30
C.3 Visual resolution measurement. 31
C.4 Possible causes for measurement errors . 31
C.5 Input signal levels .31
Annex D (normative) Complete sample specification . 33
Annex E (informative) Other issues, outside the scope of this standard, that may affect
picture clarity. 35
Annex F (informative) Possible causes of photometric measurement errors. 36
F.1 Size of measured spot. 36
F.2 Colour measurement. 36
Annex G (normative) Alternative method for measuring resolution using the NIDL grille
contrast method. 37
Annex H (informative) Photometer precision and veiling glare . 39
H.1 Photometer precision . 39
H.2 Integration time . 39
H.3 Veiling glare . 39
Annex I (informative) Light measuring devices . 41
Annex J (informative) Figure of merit for projection display colour gamut. 42
Bibliography . 44
Figure A.1 – Test patterns/measurements set-up . 25
Figure A.2 – Thirteen-point measuring grid . 26
Figure A.3 – Contrast measurement. 26
Figure A.4 – Vertical alternating lines. 26
Figure A.5 – Horizontal alternating lines. 27
Figure A.6 – Resolution equipment set-up/depth of modulation measurement. 27
Figure A.7 – Sync and blanking timing . 28
Figure C.1 − Simulation of lowered resolution . 32
– 4 – 61947-2 IEC:2001(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRONIC PROJECTION –
MEASUREMENT AND DOCUMENTATION
OF KEY PERFORMANCE CRITERIA –
Part 2: Variable 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 61947-2 has been prepared by subcommittee 100C: Audio, video
and multimedia subsystems and equipment, of 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
100/268/FDIS 100/418/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.
Annexes A, B, D, and G form an integral part of this standard.
Annexes C, E, F, H, I and J are for information only.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 3.
61947-2 IEC:2001(E) – 5 –
The committee has decided that the contents of this publication will remain unchanged until 2004.
At this date, the publication will be
reconfirmed;
withdrawn;
replaced by a revised edition, or
amended.
– 6 – 61947-2 IEC:2001(E)
INTRODUCTION
This standard was developed to ensure a common, meaningful description of key performance
parameters for variable resolution projectors (for example, CRT or laser 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 variable 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
variable resolution projectors and is not intended to provide design goals for manufacturers
of such equipment.
61947-2 IEC:2001(E) – 7 –
ELECTRONIC PROJECTION –
MEASUREMENT AND DOCUMENTATION
OF KEY PERFORMANCE CRITERIA –
Part 2: Variable resolution projectors
1 Scope
This part of IEC 61947 specifies requirements for measuring and documenting key
performance parameters for CRT and laser-based projectors and other variable resolution
projectors that are capable of multiple variable resolutions and in which the image is raster-
scanned.
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 variable resolution projectors (including projection displays that
are capable of multiple variable resolutions) that are designed for use with primarily 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 to
NTSC/RS170A, PAL, SECAM, or future HDTV, or ATV standards, which are fully described in their respective
documentation and are not within the scope of this part of IEC 61947. In this part of IEC 61947, all of these signals
are referred to as television video (TV video) (see IEC 60107-1 [27]).
Displays with fixed resolutions (i.e. individual pixel light sources or matrix displays such as
liquid crystal, DMD, plasma, or electroluminescent panels), are not fully addressed by this
standard, and reference should be made to IEC 61947-1.
Factors outside the scope of this standard that may have a bearing on projector performance
are listed in annex E. A discussion of considerations informing the development of standard
appears in annex C.
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this part of IEC 61947. For dated references, subsequent amendments
to, or revisions of, any of these publications do not apply. However, parties to agreements
based on this part of IEC 61947 are encouraged to investigate the possibility of applying the
most recent editions of the normative documents indicated below. For undated references, the
latest edition of the normative document referred to applies. Members of IEC and ISO maintain
registers of currently valid International Standards.
IEC 60050(845):1987, International Electrotechnical Vocabulary (IEV) – Chapter 845: Lighting
IEC 61947-1, Electronic projection – Measurement and documentation of key performance
1)
criteria – Part 1: Fixed resolution projectors
________
1)
To be published.
– 8 – 61947-2 IEC:2001(E)
ISO 3741:1999, Acoustics – Determination of sound power levels of noise sources using sound
pressure – Precision methods for reverberation rooms
ISO 7779:1999, Acoustics – Measurement of airborne noise emitted by information technology
and telecommunications equipment
3 Definitions
For the purposes of this part of IEC 61947, 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. 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 (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
61947-2 IEC:2001(E) – 9 –
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 the 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.
Alternatively, a successful numerical approximation has been derived by C. S. McCamy [2]. Given CIE 1931
coordinates (x, y), McCamy's approximation is CCT = 437 n3 + 3 601 n2 + 6 831 n + 5 517, where
n = (x - 0,3320)/(0,1858 – y). This approximation, the second of three proposed, is close enough for any practical
use between 2 000 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 colourimeters will report the 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
focal length of a projection lens divided by the diameter of the lens aperture
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. 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
– 10 – 61947-2 IEC:2001(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
luminance (L) 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/m )
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
61947-2 IEC:2001(E) – 11 –
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
magnesium carbonate 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]
– 12 – 61947-2 IEC:2001(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 (for example, 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 preproduction 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.
61947-2 IEC:2001(E) – 13 –
− 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.
− 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 to fill exactly 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 4H:3V 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 CCT and screen illuminance measurements.
– 14 – 61947-2 IEC:2001(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 I.
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;
(higher luminous flux values are better)
− 180 lm at 15,75 kHz horizontal and 90 Hz vertical;
− 220 lm at 36 kHz horizontal and 40 Hz vertical.
61947-2 IEC:2001(E) – 15 –
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/m (nit) at 15,75 kHz horizontal and 70 Hz vertical;
− 31 cd/m 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.
5.2.1 Example of a uniformity specification
− Brightest measurement locations: 10 % greater than average;
− Dimmest measurement locations: 5 % less than 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 16
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 (for example, 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 Blanking measurement and specification
The blanking (that portion of the raster that is forced to black to conceal the retrace or
"flyback") shall be equal to the retrace time. The blanking time shall also be in phase with the
retrace. In raster-scanned systems, the unblanked picture display time (active horizontal = T
ah
and active vertical = T ) shall be used in the visual resolution calculation and is the scan time
av
less the effective blanking time.
– 16 – 61947-2 IEC:2001(E)
T = T – T
ah sh ebh
T = T – T
av sv ebv
where
T is the active horizontal unblanked display time;
ah
T is the horizontal scan time;
sh
T is the effective horizontal blanking time;
ebh
T is the active vertical unblanked display time;
av
T is the vertical scan time;
sv
T is the effective vertical blanking time.
ebv
The effective blanking time shall be taken as the maximum time from the start of blanking or
retrace to the end of blanking or retrace.
NOTE In some devices a retrace does not exist; for example, in laser projectors where a rotating polygon scanner
is used as a horizontal deflector.
5.5 Effective blanking time
The effective blanking time shall be taken as the sum of the following:
− the out-of-phase time of the blanking and the retrace;
− the larger of the blanking or retrace times at their maximum time, as achieved by adjusting
the controls for hold, position, phase, size or any others that might be applicable;
− the unblanked picture display time that has a non-linearity greater than ±10 % compared to
the centre of the screen.
Example:
If both the blanking and retrace times equal 6,0 μs, but are 0,5 μs out-of-phase relative to each
other (due to component tolerances, frequency sensitive circuitry, or "phasing/centring" control
settings), the effective blanking is 6,5 μs. This effective blanking, while not actually blanked for
0,5 μs, is the time that the video cannot usefully be viewed, either because it is actually
blanked or because it occurs during retrace and is backwards and overlapped.
NOTE In some devices a retrace does not exist; for example, in laser projectors where a rotating polygon scanner
is used as a horizontal deflector.
5.6 Blanking specification
Example:
Blanking (lower time values are better):
− horizontal blanking: 5,8 μs or less;
− vertical blanking: 850 μs or less.
The above blanking specifications do not apply to TV video inputs (NTSC, PAL, SECAM, etc.),
if any, of the measured display device. TV video requires its own special blanking format to
eliminate objectionable spurious signals (VIR, VITS, closed captioning, burst, etc.) from being
displayed. It is encouraged that this special blanking format be used, but only during the
display of the TV video.
61947-2 IEC:2001(E) – 17 –
6 Variable resolution projector characteristics
6.1 Visual resolution measurement and specification
6.1.1 Description and general requirements
The visual resolution specification is formulated to allow users of large screen displays to
correlate the computer display directly to that of the large screen display. This specification
consists of a horizontal resolution measurement and a vertical resolution measurement.
The visual resolution specification is essentially the number of unblanked pixels that are
measured as the pixel density is increased to the point at which the modulation depth
decreases to 33 % of the contrast measurement.
For devices that do not allow enough variability in the scan rate, to implement the pixel-density
increase in this procedure, an alternative procedure shall be performed in accordance with
annex G.
The following formula shall determine the modulation depth:
L - L
peak
valley
% modulation depth = 100 D = 100
mod
L - L
white black
where
L and L are luminance measured from full-screen white and black;
white black
and
L and L are peak and valley luminances measured from a grille pattern.
peak valley
The measurements of L and L shall first be window-averaged over one pixel width
peak valley
(to minimize sensor-noise effects), and shall then be averaged over all the peaks and valleys in
the grille (to minimize grille aliasing effects).
NOTE 1 For more details on methodology, see the VESA Flat Panel Display Measurement Standard [4].
NOTE 2 Full white and black levels are measured with a large-area contrast test pattern (see figure A.3). The data
used to determine the contrast can be reused here. The modulation depth is the peak-to-peak measurement from
the minimum light output (black) to the maximum light output (within the constraints of the light output measurement
and specification). As the modulation depth decreases, the minimum light output may change to dark grey and the
maximum light output may change to light grey. The actual numbers are significant in this measurement only to
establish the 100 % and 33 % points (see figure A.6).
Measurement of the modulation depth shall be made with the same conditions, control settings,
and video levels as used in the light output specification by use of a pattern generator
(see annex B) with a test pattern of equal width (50 % duty cycle) white and black bars
(see figures A.4 and A.5).
6.1.2 Horizontal resolution
Horizontal resolution shall
...
IEC 61947-2 ®
Edition 1.0 2001-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electronic projection – Measurement and documentation of key performance
criteria –
Part 2: Variable resolution projectors
Projection électronique – Mesure et documentation des critères principaux de
performance –
Partie 2: Projecteurs à résolution variable
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IEC 61947-2 ®
Edition 1.0 2001-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electronic projection – Measurement and documentation of key performance
criteria –
Part 2: Variable resolution projectors
Projection électronique – Mesure et documentation des critères principaux de
performance –
Partie 2: Projecteurs à résolution variable
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX X
ICS 33.160.60; 35.140; 37.020 ISBN 978-2-83220-597-6
– 2 – 61947-2 IEC:2001
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references. 7
3 Definitions . 8
4 General requirements . 12
5 Light output measurement and specification . 13
5.1 Light output specifications. 14
5.1.1 Light output specification for projectors with a separate screen . 14
5.1.2 Full-black light level specification . 15
5.1.3 Luminance specification for devices with an integral screen. 15
5.2 Light output uniformity . 15
5.2.1 Example of a uniformity specification . 15
5.3 Contrast ratio . 15
5.4 Blanking measurement and specification. 15
5.5 Effective blanking time . 16
5.6 Blanking specification . 16
6 Variable resolution projector characteristics . 17
6.1 Visual resolution measurement and specification . 17
6.1.1 Description and general requirements . 17
6.1.2 Horizontal resolution . 17
6.1.3 Vertical resolution . 18
6.1.4 Procedure . 18
6.2 Video frequency response specifications . 20
6.2.1 Frequency response specifications . 20
6.3 Viewing angle (half/gain) specification for devices with an integral screen . 20
6.4 Input signal format compatibility . 20
6.5 Response time . 20
6.6 Colour measurements . 21
6.6.1 Colour chromaticity . 21
6.6.2 Colour uniformity . 21
6.7 Keystone correction . 22
7 Range of focus and image size . 22
8 Audio characteristics . 22
9 Light source specification . 22
10 Noise: maximum sound level. 23
11 Power consumption . 23
12 Weight . 23
13 Dimensions . 23
14 Recommended practices . 23
14.1 Recommended practice 1 − Sync hierarchy . 23
14.2 Recommended practice 2 − DC restoration . 23
14.3 Recommended practice 3 − Sync . 24
14.4 Recommended practice 4 − Scan range labelling . 24
Annex A (normative) Figures . 25
61947-2 IEC:2001 – 3 –
Annex B (normative) Pattern generator specifications . 29
Annex C (informative) Considerations in formulating this standard . 30
C.1 General . 30
C.2 Light output measurement. 30
C.3 Visual resolution measurement . 31
C.4 Possible causes for measurement errors. 31
C.5 Input signal levels . 31
Annex D (normative) Complete sample specification . 33
Annex E (informative) Other issues, outside the scope of this standard, that may affect
picture clarity . 35
Annex F (informative) Possible causes of photometric measurement errors . 36
F.1 Size of measured spot . 36
F.2 Colour measurement . 36
Annex G (normative) Alternative method for measuring resolution using the NIDL grille
contrast method . 37
Annex H (informative) Photometer precision and veiling glare . 39
H.1 Photometer precision . 39
H.2 Integration time . 39
H.3 Veiling glare . 39
Annex I (informative) Light measuring devices . 41
Annex J (informative) Figure of merit for projection display colour gamut . 42
Bibliography . 44
Figure A.1 – Test patterns/measurements set-up . 25
Figure A.2 – Thirteen-point measuring grid . 26
Figure A.3 – Contrast measurement . 26
Figure A.4 – Vertical alternating lines . 26
Figure A.5 – Horizontal alternating lines . 27
Figure A.6 – Resolution equipment set-up/depth of modulation measurement . 27
Figure A.7 – Sync and blanking timing . 28
Figure C.1 − Simulation of lowered resolution . 32
– 4 – 61947-2 IEC:2001
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRONIC PROJECTION –
MEASUREMENT AND DOCUMENTATION
OF KEY PERFORMANCE CRITERIA –
Part 2: Variable 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 61947-2 has been prepared by subcommittee 100C: Audio, video
and multimedia subsystems and equipment, of IEC technical committee 100: Audio, video and
multimedia systems and equipment.
This bilingual version (2013-03) corresponds to the monolingual English version, published in
2001-09.
The text of this standard is based on the following documents:
FDIS Report on voting
100/268/FDIS 100/418/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.
The French version of this standard has not been voted upon.
Annexes A, B, D, and G form an integral part of this standard.
Annexes C, E, F, H, I and J are for information only.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 3.
61947-2 IEC:2001 – 5 –
The committee has decided that the contents of this publication will remain unchanged until
2004. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
– 6 – 61947-2 IEC:2001
INTRODUCTION
This standard was developed to ensure a common, meaningful description of key performance
parameters for variable resolution projectors (for example, CRT or laser 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 variable 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
variable resolution projectors and is not intended to provide design goals for manufacturers
of such equipment.
61947-2 IEC:2001 – 7 –
ELECTRONIC PROJECTION –
MEASUREMENT AND DOCUMENTATION
OF KEY PERFORMANCE CRITERIA –
Part 2: Variable resolution projectors
1 Scope
This part of IEC 61947 specifies requirements for measuring and documenting key
performance parameters for CRT and laser-based projectors and other variable resolution
projectors that are capable of multiple variable resolutions and in which the image is raster-
scanned.
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 variable resolution projectors (including projection displays that
are capable of multiple variable resolutions) that are designed for use with primarily 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 to
NTSC/RS170A, PAL, SECAM, or future HDTV, or ATV standards, which are fully described in their respective
documentation and are not within the scope of this part of IEC 61947. In this part of IEC 61947, all of these signals
are referred to as television video (TV video) (see IEC 60107-1 [27]).
Displays with fixed resolutions (i.e. individual pixel light sources or matrix displays such as
liquid crystal, DMD, plasma, or electroluminescent panels), are not fully addressed by this
standard, and reference should be made to IEC 61947-1.
Factors outside the scope of this standard that may have a bearing on projector performance
are listed in annex E. A discussion of considerations informing the development of standard
appears in annex C.
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this part of IEC 61947. For dated references, subsequent amendments
to, or revisions of, any of these publications do not apply. However, parties to agreements
based on this part of IEC 61947 are encouraged to investigate the possibility of applying the
most recent editions of the normative documents indicated below. For undated references, the
latest edition of the normative document referred to applies. Members of IEC and ISO maintain
registers of currently valid International Standards.
IEC 60050(845):1987, International Electrotechnical Vocabulary (IEV) – Chapter 845: Lighting
IEC 61947-1, Electronic projection – Measurement and documentation of key performance
1)
criteria – Part 1: Fixed resolution projectors
________
1)
To be published.
– 8 – 61947-2 IEC:2001
ISO 3741:1999, Acoustics – Determination of sound power levels of noise sources using sound
pressure – Precision methods for reverberation rooms
ISO 7779:1999, Acoustics – Measurement of airborne noise emitted by information technology
and telecommunications equipment
3 Definitions
For the purposes of this part of IEC 61947, 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. 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 (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
61947-2 IEC:2001 – 9 –
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 the 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.
Alternatively, a successful numerical approximation has been derived by C. S. McCamy [2]. Given CIE 1931
coordinates (x, y), McCamy's approximation is CCT = 437 n3 + 3 601 n2 + 6 831 n + 5 517, where
n = (x - 0,3320)/(0,1858 – y). This approximation, the second of three proposed, is close enough for any practical
use between 2 000 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 colourimeters will report the 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
focal length of a projection lens divided by the diameter of the lens aperture
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. 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
– 10 – 61947-2 IEC:2001
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
luminance (L) 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/m )
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
61947-2 IEC:2001 – 11 –
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
magnesium carbonate 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]
– 12 – 61947-2 IEC:2001
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 (for example, 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 preproduction 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.
61947-2 IEC:2001 – 13 –
− 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.
− 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 to fill exactly 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 4H:3V 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 CCT and screen illuminance measurements.
– 14 – 61947-2 IEC:2001
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 I.
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;
(higher luminous flux values are better)
− 180 lm at 15,75 kHz horizontal and 90 Hz vertical;
− 220 lm at 36 kHz horizontal and 40 Hz vertical.
61947-2 IEC:2001 – 15 –
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/m (nit) at 15,75 kHz horizontal and 70 Hz vertical;
− 31 cd/m 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.
5.2.1 Example of a uniformity specification
− Brightest measurement locations: 10 % greater than average;
− Dimmest measurement locations: 5 % less than 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 16
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 (for example, 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 Blanking measurement and specification
The blanking (that portion of the raster that is forced to black to conceal the retrace or
"flyback") shall be equal to the retrace time. The blanking time shall also be in phase with the
retrace. In raster-scanned systems, the unblanked picture display time (active horizontal = T
ah
and active vertical = T ) shall be used in the visual resolution calculation and is the scan time
av
less the effective blanking time.
– 16 – 61947-2 IEC:2001
T = T – T
ah sh ebh
T = T – T
av sv ebv
where
T is the active horizontal unblanked display time;
ah
T is the horizontal scan time;
sh
T is the effective horizontal blanking time;
ebh
T is the active vertical unblanked display time;
av
T is the vertical scan time;
sv
T is the effective vertical blanking time.
ebv
The effective blanking time shall be taken as the maximum time from the start of blanking or
retrace to the end of blanking or retrace.
NOTE In some devices a retrace does not exist; for example, in laser projectors where a rotating polygon scanner
is used as a horizontal deflector.
5.5 Effective blanking time
The effective blanking time shall be taken as the sum of the following:
− the out-of-phase time of the blanking and the retrace;
− the larger of the blanking or retrace times at their maximum time, as achieved by adjusting
the controls for hold, position, phase, size or any others that might be applicable;
− the unblanked picture display time that has a non-linearity greater than ±10 % compared to
the centre of the screen.
Example:
If both the blanking and retrace times equal 6,0 μs, but are 0,5 μs out-of-phase relative to e
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