25TH SESSION OF THE CIE – SAN DIEGO – 25 JUNE – 2 JULY 2003files.cie.co.at/x046_2019/x046-PO116.pdf · 1 Shanghai Alpha Lighting Equipment Testing Ltd., Shanghai, CHINA [email protected]

PO116

MEASUREMENT AND ANALYSIS ON TABLE LAMPS WITH DIMMING AND TONING FUNCTIONS

Xiaobo Zhuang et al.

DOI 10.25039/x46.2019.PO116

from

CIE x046:2019

Proceedings of the

29th CIE SESSION Washington D.C., USA, June 14 – 22, 2019

(DOI 10.25039/x46.2019)

The paper has been presented at the 29th CIE Session, Washington D.C., USA, June 14-22, 2019. It has not been peer-reviewed by CIE.

CIE 2019

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilizedin any form or by any means, electronic or mechanical, including photocopying and microfilm, withoutpermission in writing from CIE Central Bureau at the address below. Any mention of organizations or products does not imply endorsement by the CIE.

This paper is made available open access for individual use. However, in all other cases all rights are reserved unless explicit permission is sought from and given by the CIE.

CIE Central Bureau Babenbergerstrasse 9 A-1010 Vienna Austria Tel.: +43 1 714 3187 e-mail: [email protected] www.cie.co.at

Zhuang, X. et al. MEASUREMENT AND ANALYSIS ON TABLE LAMPS WITH DIMMING AND TONING FUNCTIONS

MEASUREMENT AND ANALYSIS ON TABLE LAMPS WITH DIMMING AND TONING FUNCTIONS

Zhuang, X.1, Yang, Y.1, Shi, X.1 1 Shanghai Alpha Lighting Equipment Testing Ltd., Shanghai, CHINA

[email protected]

DOI 10.25039/x46.2019.PO116

Abstract

Most table lamps have the dimming and toning functions for various applications. When dimming and toning, the visual perception of flicker will increase and may do harm to end users. In this paper, the minimum dimming level of 24 models of table lamps are measured for modulation according to IEEE std 1789, Short Term Flicker Indicator (Pst

LM) according to IEC TR 61547-1 and Stroboscopic Effect (SVM) according to IEC TR 63158. And ultimately, the data are accumulated and analysed to provide a basis for the later revision of these standards.

Keywords: Table lamps, Modulation, temporal light artefacts, flicker, Short Term Flicker Indicator, Stroboscopic Effect

1 Introduction

Table lamps are common and indispensable lighting products for our daily life, and can be used for paper task lighting or transition lighting in rooms. The table lamps used for reading and writing are highly concerned by parents because most of users are children whose vision is under developing. There are many indicators for evaluating the quality of table lamps, such as modulation of flicker, illuminance and illumination uniformity, shading, colour rendering, Correlated Colour Temperature and Blue Light Hazard etc. In the latest 2018 Shanghai Quality Supervision Bureau's table lamps for reading and writing inspection, we can find that the stroboscopic results of all samples at rated power have no-observable effect according to GB/T 9473, which adopts the method of IEEE std 1789. These 24 table lamps, whose price range from 200 to 3990 CNY, mostly have the dimming and toning functions, since customers are now well aware of the benefits of having a tunable white light that match the progression of natural daylight from cool day light in the morning to warm light at night.

However, when the table lamp is dimming, the visual perception of flicker rises and it may threaten human eyes. In this paper, the minimum dimming level of each table lamp is tested for modulation according to IEEE std 1789, Short Term Flicker Indicator (Pst

LM) according to IEC TR 61547-1 and Stroboscopic Effect (SVM) according to IEC TR 63158. Then the data will be accumulated to provide a basis for the later revision of these standards.

2 The standards of light fluctuation

There are many standards related to light fluctuation, such as IEEE std 1789-2015, IEC TR 61547-1:2017, IEC TR 63158:2018, CIE TN 006-2016 and NEMA 77-2017 etc.

Proceedings of 29th CIE Session 2019 1291


Figure 1 – Comparison of IEEE 1789 Recommended Limits with Several Existing Light Sources and with SVM and Pst (Quoted from Figure 3 of NEMA 77)

The standard of IEEE std 1789 focused on health concerns and defined limits based on an apparent desire to eliminate, in all applications, all possible risk of health concerns, including photo-stimulated epileptic seizures, stroboscopic effect, migraine headaches, aggravation of autistic behaviour, and eye strain. Based on modulation and frequency, IEEE 1789 recommends three operating regions to limit the effects of TLA (temporal light artefact): No-effect (Green area), Low-Risk (Yellow area) and Risk (White area) Regions, as shown in Figure 1. According to the CQC 16-465316 certification rules, if there is a “no flicker” or similar statement in the manual, the modulation of table lamp must be in the No-effect region. In the standard of CIE TN 006:2016, TLA is introduced to define Visual perception effects, which include flicker, stroboscopic effect and phantom array. Moreover, flicker, whose frequency varies from 0 to 80 Hz, is characterized with Pst

LM of IEC TR 61547-1 for a static observer in a static environment. Stroboscopic effect, whose frequency ranges from 80 to 2000 Hz, is characterized with SVM of IEC TR 63158 for a static observer in a non-static environment. According to NEMA 77, the thresholds of Pst and SVM should below 1. The blue curves of Figure 1 where Pst = 1 (frequency<80Hz) and SVM=1 (frequency>80Hz) are shown for sine wave modulation.

3 Experiments

The modulation of table lamps, according to the standard of IEEE std 1789-2015, are measured with a Si-biased photodiode (THORLABS DET10A, rise time 1 ns), combined with an oscilloscope (Tektronix DPO 7054C, bandwidth 500 MHz, sample rate 5GS/s).

The Short Term Flicker Indicator (PstLM) and Stroboscopic Effect (SVM) are tested with

Everfine LFA-3000 Light Flickering Analyzer (V(λ) matching f1’ ≤5%, maximum sampling rate up to 100kHz) combined with Kikusui power source (PCR500LE), controlled by power source program with voltage fluctuation disturbance signal.

1292 Proceedings of 29th CIE Session 2019


Table lamps with only Dimming function

There are 12 table lamps with only dimming function (CCT fixed & brightness changed), the minimum dimming level varies from 2.8% to 41.1%, and the corresponding modulation depth is in the range of 0.6% to 24.1%. Most of the light fluctuation waveforms are triangular waves, as shown in Figure 2. According to IEEE std 1789, the flicker hazards of the 12 table lamps in the minimum dimming level are all in the no-effect region, as shown in Figure 3. Table 1 shows their modulation, Pst

LM and SVM results. PstLM and SVM are measured at the highest

voltage fluctuations, which voltage changes 4800 per minute at 40 Hz of modulation frequency according to IEC TR 61547-1, since the results are worse than the others.

Figure 2 – The typical light fluctuation waveform of table lamp at the minimum dimming level

Figure 3 – Modulation of table lamps with only dimming function at the minimum dimming level

1 10 100 1k 10k 100k 1M 10M0.1

1

10

100

Mo

dul

atio

n(%

)

Frequency (Hz)

No-Effect Region

Low

-Ris

k R

egio

n

Risk Region

7

12

98

6&115&10

14

3

2



Table 1 – Comparison between Modulation and TLA for table lamps with only dimming function

Table Lamps Photodiode + Oscilloscope LFA-3000 + Kikusui

power source

Samples Rated Power

/W

Minimum Dimming

Level f /kHz Modulation Pst

LM SVM

1 12.5 11.2% 20.3 6.25% 0.09 1.40

2 11.0 16.3% 12500 0.62% 0.10 0.00

3 6.7 41.1% 1470 1.58% 0.03 0.00

4 16.0 16.6% 19.9 5.19% 0.14 0.76

5 19.0 20.7% 22.1 11.24% 0.06 0.01

6 9.0 10.4% 18.9 14.70% 0.03 1.02

7 15.0 15.6% 1.0 1.77% 0.11 0.01

8 9.0 2.8% 18.1 24.59% 0.02 0.01

9 8.0 12.5% 15.4 19.01% 0.03 0.07

10 10.0 11.1% 21.4 10.18% 0.02 1.01

11 13.0 4.8% 20.6 14.74% 0.07 1.32

12 15.0 38.6% 3.1 6.11% 0.13 0.01

Comparing samples 6 and 8, in the lowest dimming level, their light fluctuation waveforms are all triangular waves, and the frequency is around 18 kHz, then the Pst

LM of both is very small, but the SVM of sample 6 is just higher than 1. According to the limit of NEMA 77, sample 6 is unqualified. The possible reason is the triangular wave of sample 6 has ripple, while sample 8 hasn’t. Furthermore, the 12 table lamps are all in the no-effect region, but 4 of them SVM is more than 1. The trend is not in good agreement with the results of Figure 1, since the blue curves of Figure 1 where Pst = 1 and SVM=1 are shown for sine wave.

Table lamps with Dimming and CCT tunable function

Table lamps with Dimming and CCT tunable function (CCT & brightness changed) can transform CCT at Warm White (Near 3000 K), Cool White( Near 4000 K) or Daylight (Near 6000 K) stage, and the result of 4000K at the minimum dimming level is a little poorer than others since it combines from the warm white and daylight with dimming. Figure 4 shows Modulation of 11 table lamps with dimming and CCT tunable function at the minimum dimming level of 4000K.

Figure 4 – Modulation of table lamps with dimming and CCT tunable function at the minimum dimming level of 4000K

1 10 100 1k 10k 100k0.1

1

10

100

Mod

ulat

ion(

%)

Frequency (Hz)

No-Effect Region

Low-R

isk R

egion

Risk Region 5

112

4

76

9&110

8 3



Table 2 – Comparison between Modulation and TLA for table lamps with dimming and CCT tunable function

Table Lamps at 4000K Photodiode + Oscilloscope LFA-3000 + Kikusui

power source

Samples Rated Power

/W

Minimum Dimming

Level f /kHz Modulation Pst

LM SVM

1 10.0 6.5% 18.1 15.85% 0.04 1.16

2 10.0 3.8% 4.7 59.09% 0.04 1.34

3 10.0 18.8% 31.2 6.07% 0.01 0.00

4 17.0 12.1% 2.0 4.03% 0.04 0.05

5 10.0 19.0% 0.1 3.38% 0.19 0.09

6 10.0 14.0% 14.4 2.68% 0.52 0.00

7 15.0 24.1% 5.0 1.84% 0.07 0.00

8 18.0 29.8% 24.1 6.20% 0.02 0.00

9 12.0 6.1% 18.4 16.92% 0.97 1.07

10 10.0 14.0% 26.6 10.17% 0.13 0.04

11 12.0 10.6% 1.5 85.14% 0.04 1.15

Table 2 and Figure 4 show sample 5 and 11 are in the Low-Risk region, and sample 1, 2, 9, 11 SVM are more than 1. Besides, some samples’ SVM is too low to detect, since the frequency of waveform is high and no ripple on it.

Table lamps with Dimming and Colour tunable function

The modulations of table lamp with dimming and colour tunable function (colour & brightness changed) with different CCT or colour are described in Figure 5. The modulation depth of different CCT are 100% at the lowest dimming level, since the table lamp is an RGB and tuneable white colour mixing product with PWM regulation. Moreover, table 3 shows the table lamp’s SVM with different CCT are much greater than 1, so it’s an unqualified product on TLA.

Figure 5 – Modulation of table lamp with dimming and colour tunable function at the minimum dimming level

1 10 100 1k0.1

1

10

100

Mo

dula

tion(

%)

Frequency (Hz)

No-Effect Region

Risk Region

Low-Risk

Region

2517K/3172K/5865K

Red/Yellow/Green



Table 3 – Comparison between Modulation and TLA for table lamp with dimming and colour tunable function

Table Lamp Photodiode + Oscilloscope LFA-3000 + Kikusui power

source

CCT/Colour Minimum

Dimming Level f /kHz Modulation Pst

LM SVM

2517K 13.5% 0.116 100% 0.06 5.84

3172K 12.0% 0.116 100% 0.11 7.52

5865K 12.3% 0.116 100% 0.08 7.53

Red 12.3% 5.4 48.68% 0.01 0.67

Yellow 12.0% 5.4 52.87% 0.01 0.95

Green 12.3% 5.4 55.26% 0.01 0.64

4 Results and discussion

As shown in Figure 3&4 and table 1&2, even though the modulations of table lamps are in the no-effect region, they may fail in the SVM tests. While NEMA 77 Figure 3 describes Pst = 1 and SVM=1 for sine wave are in the Risk region.

In addition, even if the two table lamps have similar frequencies and similar fluctuation depths, the evaluation results are completely different due to the existence of waveform ripple. The frequency of table lamp with RGB and tuneable white colour mixing at the minimum dimming level is 116 Hz, and it has the visible flicker in the darkroom, while the Pst is very low.

Due to the numerous dimming and tonging stage, the current table lamp standard only requires TLA at rated power. The test found that 9 of the 24 table lamps with dimming level are unqualified on SVM, and 3 of them are failed on modulation. Consumers are prone to use table lamps in dimming and coloring, and it is recommended that TLA should be limit in all dimming and toning conditions in the next edition of standards.

References

IEEE 2015. STD 1789 – IEEE Recommended Practices of Modulating Current in High Brightness LEDs for Mitigating Health Risks to Viewers.

CIE 2016. CIE TN 006:2016. Visual Aspects of Time-Modulated Lighting Systems – Definitions and Measurement Models, 2016. Vienna: CIE.

IEC, 2017. IEC TR 61547-1-2017. Equipment for general lighting purposes – EMC immunity requirements–Part 1: An objective light flickermeter and voltage fluctuation immunity test method.

IEC, 2018. IEC TR 63158-2018. Equipment for general lighting purposes – Objective test method for stroboscopic effects of lighting equipment.

SAC/TC224 2017. GB/T 9473. Performance requirements for table lamps for paper task.

CQC, 2018. CQC 31-465318. Performance certification rules for table lamps for paper task.

NEMA, 2017. NEMA 77-2017. Temporal Light Artifacts: Test Methods and Guidance for Acceptance Criteria.


Documents

25TH SESSION OF THE CIE – SAN DIEGO – 25 JUNE – 2 JULY 2003files.cie.co.at/x046_2019/x046-PO116.pdf · 1 Shanghai Alpha Lighting Equipment Testing Ltd., Shanghai, CHINA [email protected]