GB/T 43979-2024 PDF in English
GB/T 43979-2024 (GB/T43979-2024, GBT 43979-2024, GBT43979-2024)
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valuation methods for visual comfort of indoor LED displays
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Standards related to (historical): GB/T 43979-2024
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GB/T 43979-2024: PDF in English (GBT 43979-2024) GB/T 43979-2024
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 31.120
CCS L 53
Evaluation methods for visual comfort of indoor LED
displays
ISSUED ON. APRIL 25, 2024
IMPLEMENTED ON. APRIL 25, 2024
Issued by. State Administration for Market Regulation;
National Standardization Administration.
Table of Contents
Foreword... 3
1 Scope... 4
2 Normative references... 4
3 Terms and definitions... 4
4 General requirements... 4
4.1 Test conditions... 4
4.2 Test instruments and software... 5
4.3 Test status... 5
5 Evaluation method... 6
5.1 Visual refresh rate... 6
5.2 Display brightness (ambient illumination)... 7
5.3 Bright room contrast... 8
5.4 Display and ambient brightness ratio... 9
5.5 Illuminance of the display at the observer's position... 10
5.6 Chromaticity non-uniformity... 12
5.7 Subjective evaluation... 13
Evaluation methods for visual comfort of indoor LED
displays
1 Scope
This document describes the light comfort evaluation method for indoor LED display
(hereinafter referred to as "LED displays").
This document is applicable to the evaluation of light comfort of LED displays.
2 Normative references
The contents of the following documents constitute the essential terms of this document
through normative references in the text. Among them, for dated references, only the
version corresponding to that date applies to this document; for undated references, the
latest version (including all amendments) applies to this document.
GB/T 43770-2024 Specification for indoor LED displays
GB/T 43978-2024 Evaluation requirements for visual comfort of indoor LED
displays
SJ/T 11141-2017 Generic specification for LED displays
SJ/T 11281-2017 Measure methods of light emitting diode (LED) displays
3 Terms and definitions
The terms and definitions, which are defined in GB/T 43770-2024, GB/T 43978-2024,
SJ/T 11141-2017, SJ/T 11281-2017, apply to this document.
4 General requirements
4.1 Test conditions
Unless otherwise specified, the test conditions are as follows.
a) Ambient temperature. 15 °C ~ 35 °C;
b) Relative humidity. 20% ~ 80%;
c) Atmospheric pressure. 86 kPa ~ 106 kPa;
d) AC power supply. (220 ± 22) V, (50 ± 1) Hz;
e) Test environment. There shall be no mechanical vibration, electromagnetic and
photoelectric interference that may affect the test accuracy;
f) Test distance. All tests are conducted outside the minimum line of sight.
4.2 Test instruments and software
Unless otherwise specified, the performance of all test instruments shall meet the
following requirements and be calibrated by a third-party organization. During the
calibration period, the test shall be conducted in accordance with the relevant operating
procedures.
a) Color luminance meter (similar instruments used to test optical properties such as
brightness and chromaticity can also be used). The relative indication error of
brightness is within ±5%; the absolute indication error of chromaticity
coordinates is within ±0.003 (relative to standard A light source).
b) Imaging brightness meter. Relative brightness indication error within ±5%.
c) Illuminance meter. Relative illumination indication error within ±4%.
d) Thermometer. Absolute temperature indication error within ±0.5 °C.
e) Laser rangefinder. Absolute distance indication error within ±1 mm.
f) Photoelectric sensor. Frequency response not less than 50 MHz.
g) Oscilloscope. Bandwidth not less than DC 100 MHz.
h) Test software. It shall meet actual test requirements.
4.3 Test status
Unless otherwise specified, the test status is as follows.
a) Before the test, the LED display shall light up all light-emitting diodes at 30% of
the maximum brightness; the preheating time shall not be less than 15 min;
b) Before the test, the LED display shall be debugged to the best state; the
configuration parameters and working status of the LED display shall not be
changed during the test.
5 Evaluation method
5.1 Visual refresh rate
5.1.1 Test conditions
The test conditions are as follows.
a) The ambient illumination changes within ±10%; there is no obvious colored light
source;
b) The photoelectric sensor is placed in front of the normal direction of the LED
display pixel; the distance between the photoelectric sensor and the pixel point
should be such that the pixel light intensity can be radiated to the light receiving
target surface of the photoelectric sensor;
c) During the test, the angle between the observation line and the LED display
remains unchanged.
5.1.2 Test steps
The test steps are as follows.
a) According to Figure 1, the LED display is set to the highest grayscale level and
the highest brightness level. According to the requirements of B.3.5 of SJ/T
11281-2017, a special test image for visual refresh rate is displayed in the display
window;
b) The LED display shows the standard test image for visual refresh rate;
c) Connect the signal input end of the oscilloscope to the signal output end of the
photoelectric sensor;
d) Adjust the oscilloscope; select the appropriate range, so that its output presents a
stable and regular waveform;
e) Observe the waveform and measure the period T of a set of waveforms;
f) Calculate the visual refresh rate FC of the display according to formula (1).
Where.
pixels;
c) During the test, the angle between the observation line and the LED display
remains unchanged.
5.3.2 Test steps
The test steps are as follows.
a) According to the method in 5.2, measure the brightness Lmax and background
brightness Ld on the normal line of the LED display, respectively;
b) Calculate the bright room contrast Cd of the display, according to formula (3).
Where.
Cd - Brightness contrast, Cd = 1;
Lmax - Brightness of LED display, in candela per square meter (cd/m2);
Ld - Background brightness, in candela per square meter (cd/m2).
5.4 Display and ambient brightness ratio
5.4.1 Test conditions
The test conditions are as follows.
a) The ambient illumination changes within ±10%; there is no obvious colored light
source;
b) The acquisition range of the imaging brightness meter shall not be less than 60°
field of view;
c) During the test, the angle between the observation line and the LED display
remains unchanged.
5.4.2 Test steps
The test steps are as follows.
a) According to Figure 3, at the highest grayscale and highest brightness level, the
LED display shows a certain primary color; the average brightness Lavg of the
LED display is tested by an imaging brightness meter;
b) At the highest grayscale and highest brightness level, the LED display shows a
b) The illuminance meter probe shall be directly facing the center point area of the
display; the probe height is the observer's eye height. The eye height of the sitting
observer shall be 1.2 m; the eye height of the standing observer shall be 1.5 m;
c) During the test, the angle between the observation line and the LED display
remains unchanged.
5.5.2 Test steps
The test steps are as follows.
a) According to Figure 4, when the LED display is in full black, use an illuminance
meter to test the background illumination Ed of the LED display;
b) At the highest grayscale level and the highest brightness level, the LED display
shows a certain primary color; use an illuminance meter to test the illumination
Emax of the LED display;
c) Calculate the maximum illumination of the primary color according to formula
(5).
Where.
E - Maximum illumination, in lux (lx);
Emax - Illumination of the LED display, in lux (lx);
Ed - Background illumination of the LED display, in lux (lx).
d) Use the above method to test the maximum illumination of the red field, green
field, blue field, yellow field, white field (under the specified white field
chromaticity coordinates) as needed;
e) The maximum value is the illumination of the display at the observer's position.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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