Application Note

Light Emitting Diode

LED Flicker in
Lamps or Luminaires

Table of contents
1. Overview ................................................................................ 2
2. Primary Cause of LED Flicker .......................................... 2
3. Standards for Flicker in LED Lamps/Luminaires ....... 3
4. Evaluation of LED Flicker .................................................. 5
5. Evaluation Results ............................................................... 6
6. Summary .............................................................................. 16

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Application Note
1. Overview
Depending on the situation, some people may detect flicker in fluorescent lamps and some other typesof lamps/luminaires operating at the frequency of general-purpose alternating current (i.e. 50/60 Hz
depending on the country/region) or even double frequency (i.e. 100/120 Hz). Flicker, however, is not the
only issue for these lamps/luminaires. For LED lamps/luminaires, if a poorly designed power supply is used
to drive the LEDs (e.g. LED drivers incapable of sufficiently smoothing the current, etc.), the lamp/luminaire
may have a visible flicker and it may have a negative impact on human health (e.g. headache, dizziness,fatigue, nausea, eye strain, etc.). To minimize safety/health hazards from lamps/luminaires, themanufacturers may be required to meet applicable statutory/regulatory requirements to be able to sell
the lamps/luminaires.
For those reasons, when designing an LED lamp/luminaire flicker is an issue that must be dealt with andsufficient verification should be performed to ensure that the lamp/luminaire has no flicker. Since flicker

Light Emitting Diodein LED lamps/luminaires relates to the waveform pattern (i.e. frequency, amplitude and their combination),
Nichia performed an evaluation to determine the waveform patterns that may create visible flicker. In
addition to measurements of flicker metrics, the evaluation results include data collected using a sensory
analysis since flicker is subjective and can vary from person to person.
Note that the evaluation results/data do not represent the performance of the LEDs. An important point
to understand when designing a flicker-free lamp/luminaire is that the chosen LED driver will have a great
impact on the light output of the LED. Additionally, the conclusions and recommendations discussed inthis application note are merely Nichia’s opinions based on the results and findings of the evaluation;
simply following them does not guarantee that the chosen application will be free from flicker issues.
Sufficient verification should be performed using the chosen lamp/luminaire (i.e. assembled as completely
as possible in its intended use environments) to ensure that there are no issues.

2. Primary Cause of LED Flicker
Flicker in LED lamps/luminaires are usually due to the LED driver. LEDs are devices that respond very
quickly to current variations (i.e. fast response time). As shown in Figure 1 below, the light output
waveform of LEDs is almost proportional to the waveform of the current passing through the LED. As thedifference in the brightness (i.e. the amplitude between the peak and fall) and the intervals between the
waves increase (i.e. low frequency), so does the likelihood of visible flicker in the light output. This may
not be the case when LEDs are used with an LED driver with proper current control (e.g. pulse-widthmodulation [PWM] dimming control, etc.); if only the amplitude is large and the frequency is sufficiently
high, flicker will not be detected by the human eye.
However, if a low performance LED driver is used, as shown in Figure 2 (i.e. incapable of smoothing) the
output current waveform is more likely to have a large amplitude; if this output current waveform has a
low frequency1, it may increase the likelihood of causing flicker in the LED light output. Another concernof using an LED driver incapable of sufficiently smoothing is that the current flowing through the LED may
exceed the absolute maximum rating current.
Note:
1

Inexpensive, low-quality LED drivers are prone to have a frequency of 100/120 Hz (i.e. double frequency of the general-purpose AC).
These frequencies are too low and may cause the LED to flicker.

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Application Note
This may occur due to the fluctuating output current waveform of these LED drivers; even if the average
output current value is below the absolute maximum rating current, the current may easily exceed theabsolute maximum rating current at the peak of the waves. Nichia recommends using an LED drivercapable of smoothing the output current as shown in Figure 3. To design a flicker-free LED lamp/luminaire,
it is very important to select/design a proper LED driver.
光出力波形

LED電流波形－LED light output waveform－Output current waveform
0

10

20
30
[msec]

40

50

Light Emitting Diode

Figure 1. Output current vs LED light output

0

10

20
30
[msec]

40

50

0

10

20
30
[msec]

40

50

Figure 2. Example of an output

Figure 3. Example of an evenly

current with large variations

smoothed output current

3. Standards for Flicker in LED Lamps/Luminaires
3.1. Japan Electrical Appliances and Materials Safety Act
The Act on Product Safety of Electrical Appliances and Materials (known as the “PSE Act”) and orders from
the Ministry of Economy, Trade and Industry (METI) include LED lamps and luminaires for general lighting
applications and stipulate that the lamp/luminaire must not create a sensation that the light output isflickering (i.e. technical requirement). In its official correspondences (i.e. Dear Colleague letters), METI has
clarified this requirement; LED lamps/luminaires must meet either of the following standards:
1)

There are no gaps in the light output (i.e. ≤ 5% of the peak light output) and theperiodic frequency is ≥ 100 Hz.

2)

The pulse repetition frequency (PRF) is ≥ 500 Hz.

For example, the waveform shown in Figure 4 below meets the first standard above with the PRF = 100
Hz and the minimum light output = 80% of the peak. However, the waveform shown in Figure 5 below
does not meet either set of the standards above since there are gaps in the light output and the PRF <500 Hz. If an LED luminaire has the same light output characteristics shown in Figure 5, it will be considered
unacceptable to the requirements of the PSE Act.

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Application Note120
光出力[%] [%]
OutputLight

光出力[%] [%]
Output
Light

120
100
80
60
40
20
0

100
80
60
40
20

Gaps

0

0

5

10

15

20

25

0

5

[msec]
Time[msec]

10

15

20

25

[msec]
Time[msec]

Figure 4. Example of a PSE-

Figure 5. Example of a PSE non-compliant light output waveformcompliant light output waveform

3.2. Flicker Metrics: Percent Flicker and Flicker Index
There are several metrics/tools to quantify flicker (e.g. percent flicker, flicker index, etc.), and laboratory

Light Emitting Diodetesting and reporting may be required for product certification (e.g. Energy Star program).
Percent flicker:
It is “a relative measure of the cyclic variation in output of a light source (percent modulation)” 2,
represented by equation 1 below. The value can vary from 0 to 100%. The lower the percentage is, thesmaller the variation and when it is 0% the waveform becomes completely flat; the higher the percentage
is, the larger the variation and when it is 100% the waveform indicates the lamp/luminaire is cycling
between on and off.
Flicker index:
It is “a measure of the cyclic variation in output of a light source taking into account the waveform of thelight output”2 and “the ratio of the area under the light output curve that is above the average light output
level to the total area under the light output curve for a single cycle”2. The value can be calculated byequation 2 below and can vary from 0 to 1; like percent flicker, the smaller the value is the smaller thevariation.
Note that both metrics do not take into consideration the frequency factor; a high percent flicker/flicker
index value does not necessarily lead to flicker. For example, a lamp/luminaire that has light output gaps
with 100 percent flicker will not cause visible flicker when the periodic frequency is sufficiently high (i.e. ≥several kHz)Equation 1:
max.

𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑓𝑙𝑖𝑐𝑘𝑒𝑟 ＝ 100 ×Area (A)
>Avg.
<Avg.
Avg.

光出力
Light
outputmin.
Area (B)

Equation 2:
𝐹𝑙𝑖𝑐𝑘𝑒𝑟 𝑖𝑛𝑑𝑒𝑥 ＝Note:Area (A):Area (B):Figure 6. Percent flicker and flicker index

𝑚𝑎𝑥 − 𝑚𝑖𝑛𝑚𝑎𝑥 + 𝑚𝑖𝑛𝐴𝑟𝑒𝑎 (𝐴)(𝐴)
𝐴𝑟𝑒𝑎+ 𝐴𝑟𝑒𝑎 (𝐵)Area under the light output curve that is above
the average light output level.
Area under the light output curve that is below
the average light output level.

Note:
2

ANSI/IES RP-16-10

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Application Note
4. Evaluation of LED Flicker
Nichia performed an evaluation to determine the change in flicker when the frequency and amplitude of
the output current from an LED driver are varied.
4.1. Requirements for Measuring Equipment: Photodetectors and Oscilloscopes
For the evaluation, proper measuring instruments are required to capture the light signals (i.e. LED light
output) and convert them into a graphical representation (i.e. waveform). For example, if a photometer isused to measure the light output in lux (i.e. illuminometer), choose one that is capable of:-continuously measuring the light output-

responding quickly enough to the frequency of the light output waveform-converting the sampled digital data to an analog voltage waveform (when an oscilloscope is used

Light Emitting Diodewith this illuminometer to graphically display the light signals)
There is another type of photodetector using a photodetector device and an amplifier to increase thepower of a signal (i.e. photodetector circuit shown in Figure 7 below). This system also requires anoscilloscope to display the waveform.

AmplifierCircuitV+

Connected to an
oscilloscope
V-

Photodetector device(e.g. photodiode)Figure 7. Example of a photodetector circuit
4.2. Evaluation Objectives/Method
This evaluation was performed to determine:
the relationship between the output current frequency of the LED driver (i.e. 50 to 500 Hz) 3 and-LED flicker
the relationship between the waveform amplitude4 and LED flicker-

In the evaluation, the minimum light output5, percent flicker, and flicker index were calculated for eachwaveform condition to quantify the level of flicker. Additionally, the level of perceived flicker was evaluatedboth when the observer viewed the emitting area of the LEDs and when the observer made quick
movements (e.g. writing, hand waving, etc.) while illuminated by the LEDs.

Note:
3

The periodic frequency of the output current waveform after rectified by the internal diode bridge (i.e. 100 Hz, 150 Hz, 300 Hz, 500 Hz,
and 1 kHz) was twice the original frequency.

4

Smoothing capacitors with different capacitances were used for the LED driver to generate waveforms with different amplitudes.

5

The minimum light output values were determined and expressed in a percentage as a fraction of the maximum light output value of the
waveform.

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Application Note
For the equipment configuration used to evaluate the light output waveforms, refer to Figure 8 below andfor the method to evaluate the perceived flicker level, refer to Figure 9 below.

Light-Tight Enclosure

100VAC
50 to 500Hz

LED Driver
Circuit

LED Light
EngineRipple varies
depending on
smoothing capacitor

Light Emitter

Photodetector
Light Receiver

Oscilloscope

Light Emitting Diode

Figure 8. Equipment configuration used to measure the light output waveforms

100VAC
50 to 500Hz

LED Driver
Circuit
Ripple varies
depending on
smoothing capacitor

LED Light
EngineObserverFigure 9. Equipment configuration used to perform the sensory evaluation

5. Evaluation Results
Section 5.1 below only presents measurement and observation data. Interpretation and discussion of thisdata is presented in later sections: 5.2 (i.e. Summary of findings) and 5.3 (i.e. Conclusion andrecommendations).

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Application Note
5.1. Waveform Measurement
5.1.1. Repetition Frequency: 100 Hz
120－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

光出力[%] [%]
Output
Light

100
80
60
40
20

Min. light output：

0 [%]Percent flicker：

100 [%]

Flicker index：

0.55

Observation result:

Flicker was perceived.

Min. light output：

1 [%]Percent flicker：

97 [%]

Flicker index：

0.42

Observation result:

Flicker was perceived.

Min. light output：

8 [%]Percent flicker：

85 [%]

Flicker index：

0.30

Observation result:

Flicker was perceived.

Min. light output：

17 [%]

Percent flicker：

71 [%]

Flicker index：

0.22

Observation result:

Flicker was perceived.

0
0

5

10
15
Time
[msec][msec]

20

25

Figure 10. 100Hz-1－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

光出力[%] [%]
Output
Light

100
80
60

40
20
0
0

5

10
15
Time
[msec][msec]

20

25

Figure 11. 100Hz-2
120－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

Light
光出力Output[%] [%]

100
80
60

40
20
0
0

5

10
15
Time
[msec][msec]

20

25

Figure 12. 100Hz-3
120－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

100
光出力[%] [%]
OutputLight

Light Emitting Diode

120

80
60
40
20
0
0

5

10
15
Time
[msec][msec]

20

25

Figure 13. 100Hz-4

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Application Note120

－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

OutputLight
光出力[%] [%]

100
80
60
40
20

Min. light output：

32 [%]

Percent flicker：

51 [%]

Flicker index：

0.15

Observation result:

No flicker was perceived.

Min. light output：

78 [%]

Percent flicker：

13 [%]

Flicker index：

0.03

Observation result:

No flicker was perceived.

Min. light output：

0 [%]Percent flicker：

100 [%]

Flicker index：

0.55

Observation result:

Flicker was perceived.

Min. light output：

3 [%]Percent flicker：

93 [%]

Flicker index：

0.38

Observation result:

Flicker was perceived.

0
0

5

10
15
Time
[msec][msec]

20

25

Figure 14. 100Hz-5
120－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

OutputLight
光出力[%] [%]

80
60
40

20
0
0

5

10
15
Time
[msec][msec]

20

25

Figure 15. 100Hz-6
5.1.2. Repetition Frequency: 150 Hz

Light Output
光出力[%] [%]

120－LED light output waveform
光出力波形
光出力平均
－Avg.
LED light output

100
80
60
40
20
0
0

5

10
15
Time
[msec][msec]

20

25

Figure 16. 150Hz-1
120－LED light output waveform
光出力波形
光出力平均
－Avg.
LED light output

100

Light Output
光出力[%] [%]

Light Emitting Diode

100

80
60
40
20
0
0

5

10
15
Time
[msec][msec]

20

25

Figure 17. 150Hz-2

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Application Note120

－LED light output waveform
光出力波形
光出力平均
－Avg.
LED light output

Light
光出力Output[%] [%]

100

Min. light output：

14 [%]

80

Percent flicker：

76 [%]

60

Flicker index：

0.25

40

Observation result:

Flicker was perceived.

20
0
0

5

10
15
Time
[msec][msec]

20

25

Figure 18. 150Hz-3
120－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

OutputLight
光出力[%] [%]

Min. light output：

24 [%]

80

Percent flicker：

61 [%]

60

Flicker index：

0.18

Observation result:

Flicker was perceived when40

20

the object was moving fast.

0
0

5

10
15
Time
[msec][msec]

20

25

Figure 19. 150Hz-4
120－LED light output waveform
光出力波形
光出力平均
－Avg.
LED light output

Light
光出力Output[%] [%]

100
80
60
40
20

Min. light output：

41 [%]

Percent flicker：

42 [%]

Flicker index：

0.11

Observation result:

No flicker was perceived.

Min. light output：

81 [%]

Percent flicker：

11 [%]

Flicker index：

0.02

Observation result:

No flicker was perceived.

0
0

5

10
15
Time
[msec][msec]

20

25

Figure 20. 150Hz-5
120－LED light output waveform
光出力波形
光出力平均
－Avg.
LED light output

100

OutputLight
光出力[%] [%]

Light Emitting Diode

100

80
60

40
20
0
0

5

10
15
Time
[msec][msec]

20

25

Figure 21. 150Hz-6

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Application Note
5.1.3. Repetition Frequency: 300 Hz
120－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

光出力[%] [%]
Output
Light

100
80
60
40
20

Min. light output：

0 [%]Percent flicker：

100 [%]

Flicker index：

0.53

Observation result:

Flicker was perceived.

Min. light output：

10 [%]

Percent flicker：

81 [%]

Flicker index：

0.28

Observation result:

Flicker was perceived when

0
0

2

4

6

8

10

Time
[msec][msec]

Figure 22. 300Hz-1
120－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

OutputLight
光出力[%] [%]

80
60
40

20

the object was moving fast.

0
0

2

4

6

8

10

[msec]
Time[msec]

Figure 23. 300Hz-2
120－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

OutputLight
光出力[%] [%]

100
80
60
40
20

Min. light output：

26 [%]

Percent flicker：

59 [%]

Flicker index：

0.17

Observation result:

Flicker was perceived when
the object was moving fast.

0
0

2

4
6
Time
[msec][msec]

8

10

Figure 24. 300Hz-3
120－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

100
光出力[%] [%]
OutputLight

Light Emitting Diode

100

80
60

40
20

Min. light output：

40 [%]

Percent flicker：

43 [%]

Flicker index：

0.12

Observation result:

No flicker was perceived.

0
0

2

4
6
Time
[msec][msec]

8

10

Figure 25. 300Hz-4

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Application Note120

－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

光出力[%] [%]
Light Output

100
80
60

40
20

Min. light output：

57 [%]

Percent flicker：

28 [%]

Flicker index：

0.07

Observation result:

No flicker was perceived.

Min. light output：

89 [%]

Percent flicker：

6 [%]Flicker index：

0.01

Observation result:

No flicker was perceived.

Min. light output：

0 [%]Percent flicker：

100 [%]

Flicker index：

0.51

Observation result:

Flicker was perceived when

0
0

2

4
6
Time
[msec][msec]

8

10

Figure 26. 300Hz-5
120－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

光出力Output[%] [%]
Light

80
60
40

20
0
0

2

4
6
Time
[msec][msec]

8

10

Figure 27. 300Hz-6
5.1.4. Repetition Frequency: 500 Hz
120－LED light output waveform
光出力波形
光出力平均
－Avg.
LED light output

Light Output
光出力[%] [%]

100
80
60
40
20

the object was moving fast.

0
0

2

4
6
Time
[msec][msec]

8

10

Figure 28. 500Hz-1
120－LED light output waveform
光出力波形
光出力平均
－Avg.
LED light output

100

Light Output
光出力[%] [%]

Light Emitting Diode

100

80
60
40
20

Min. light output：

18 [%]

Percent flicker：

69 [%]

Flicker index：

0.22

Observation result:

No flicker was perceived.

0
0

2

4
6
Time
[msec][msec]

8

10

Figure 29. 500Hz-2

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Application Note120

－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

OutputLight
光出力[%] [%]

100
80
60
40
20

Min. light output：

39 [%]

Percent flicker：

44 [%]

Flicker index：

0.13

Observation result:

No flicker was perceived.

Min. light output：

52 [%]

Percent flicker：

31 [%]

Flicker index：

0.08

Observation result:

No flicker was perceived.

Min. light output：

67 [%]

Percent flicker：

20 [%]

Flicker index：

0.05

Observation result:

No flicker was perceived.

Min. light output：

91 [%]

Percent flicker：

5 [%]Flicker index：

0.01

Observation result:

No flicker was perceived.

0
0

2

4

6

8

10

Time
[msec][msec]

Figure 30. 500Hz-3
120－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

OutputLight
光出力[%] [%]

80
60

40
20
0
0

2

4

6

8

10

Time
[msec][msec]

Figure 31. 500Hz-4
120－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

Light
光出力Output[%] [%]

100
80
60
40

20
0
0

2

4
6
Time
[msec][msec]

8

10

Figure 32. 500Hz-5
120－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

100

OutputLight
光出力[%] [%]

Light Emitting Diode

100

80
60
40
20
0
0

2

4
6
Time
[msec][msec]

8

10

Figure 33. 500Hz-6

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Application Note
5.1.5. Repetition Frequency: 1 kHz
120－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

OutputLight
光出力[%] [%]

100
80
60

40
20

Min. light output：

0 [%]Percent flicker：

100 [%]

Flicker index：

0.48

Observation result:

No flicker was perceived.

Min. light output：

35 [%]

Percent flicker：

49 [%]

Flicker index：

0.14

Observation result:

No flicker was perceived.

Min. light output：

56 [%]

Percent flicker：

28 [%]

Flicker index：

0.08

Observation result:

No flicker was perceived.

Min. light output：

67 [%]

Percent flicker：

20 [%]

Flicker index：

0.05

Observation result:

No flicker was perceived.

0
0

1

2

3

4

5

[msec]
Time[msec]

Figure 34. 1kHz-1
120－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

OutputLight
光出力[%] [%]

80
60
40

20
0
0

1

2

3

4

5

[msec]
Time[msec]

Figure 35. 1kHz-2
120－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

Light
光出力Output[%] [%]

100
80
60
40
20
0
0

1

2

3

4

5

Time
[msec][msec]

Figure 36. 1kHz-3
120－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

100

OutputLight
光出力[%] [%]

Light Emitting Diode

100

80
60

40
20
0
0

1

2
3
Time
[msec][msec]

4

5

Figure 37. 1kHz-4

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Application Note120

－LED light output waveform
光出力平均
光出力波形
－Avg. LED light output

Light Output
光出力[%] [%]

100
80
60
40
20

Min. light output：

78 [%]

Percent flicker：

12 [%]

Flicker index：

0.03

Observation result:

No flicker was perceived.

Min. light output：

95 [%]

Percent flicker：

3 [%]Flicker index：

0.01

Observation result:

No flicker was perceived.

0
0

1

3
2
Time
[msec][msec]

5

4

Figure 38. 1kHz-5
120－LED light output waveform
光出力波形
光出力平均
－Avg. LED light output

Light Output
光出力[%] [%]

Light Emitting Diode

100
80
60
40
20
0
0

2

4
6
Time
[msec][msec]

8

10

Figure 39. 1kHz-6

5.2. Summary of Findings
The measurement and observation results shown in 5.1 can be interpreted as follows:- When the percent flicker was ≤ 40%, the observer had no sensation of flicker in the light output under
any of the evaluated repetition frequency conditions (see Figure 40 below).
- When the flicker index was ≤ 0.1%, the observer had no sensation of flicker in the light output under
any of the evaluated frequency conditions (see Figure 41 below).
- The higher the frequency was, the less likely it was to create a sensation that the light output was
flickering; at 1 kHz frequency, the observer had no sensation of flicker in the light output regardlessof the percent flicker and flicker index value (see Figures 40 and 41 below).
- When the minimum light output was ≥ 40%, the observer had no sensation of flicker in the light
output under any of the evaluated repetition frequency conditions (see Figure 42 below).

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Application Note

No flicker was
ちらつきを感じない
perceived.
Flicker was perceived
素早い動きでwhen the object was
ちらつきを感じる
moving fast.

100Hz

Flicker wasperceived.
ちらつきを感じる

500Hz

150Hz
300Hz
1kHz

0

20

40
60
パーセントフリッカー[%]
Percent Flicker [%]

80

100

Light Emitting Diode

Figure 40. Perceived flicker vs. percent flicker [%]No flicker was
ちらつきを感じない
perceived.
Flicker was perceived
when the素早い動きでobject was
ちらつきを感じる
moving fast.

100Hz

Flicker wasperceived.
ちらつきを感じる

500Hz

150Hz
300Hz
1kHz

0.0

0.1

0.2
0.3
0.4
フリッカーインデックス
Flicker Index

0.5

0.6

Figure 41. Perceived flicker vs. flicker index

No flicker was
ちらつきを感じない
perceived.
Flicker was perceived
when the素早い動きでobject was
ちらつきを感じる
moving fast.

100Hz

Flicker wasperceived.
ちらつきを感じる

500Hz

150Hz
300Hz
1kHz

0

20

40

60

80

100

最小レベル
[%] [%]
Minimum
Light Output

Figure 42. Perceived flicker vs. minimum light output [%]This document contains tentative information, Nichia may change the contents without notice.
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Application Note
5.3. Conclusion and Recommendations
As mentioned earlier in this application note, the PSE Act and METI orders require that LED
lamps/luminaires create no sensation of flicker in the light output at a repetition frequency ≥ 100 Hz andthe minimum light output ≥ 5%. However, the evaluation results revealed that light output waveforms
meeting this requirement may still create a sensation of flicker.
For the percent flicker and the minimum light output level, there is a relationship between the twovariables shown in Figure 43 since only the maximum and minimum light output values are required to
calculate percent flicker.

[%]
Percent Flicker [%]パーセントフリッカー

Light Emitting Diode

100
80

100Hz
150Hz

60

300Hz
No flicker was perceived

40

500Hz

1kHz

20

0
0

20

40

60

80

100

Minimum
Light Output
[%]
最小レベル
[%]
Figure 43. Minimum light output level [%] vs. percent flicker [%]6. Summary
This application note has demonstrated the relationship between the frequency/amplitude of the light
output waveform and flicker in LED lamps/luminaires. Nichia hopes that this information is helpful whenselecting/designing an LED driver for the chosen application. However, it includes results based on asensory evaluation using the human eye under Nichia’s evaluation conditions/environments (e.g.
observer, ambient conditions, light output with special waveforms such as Square, Triangular, etc.) andresults may not be the same under different conditions/environments. Verification of the chosen
application must be performed assembled with the LEDs and LED driver properly in place to ensure
there is no flicker in the light output.

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Application Note

Light Emitting Diode

Disclaimer
This application note is a controlled document of Nichia Corporation (Nichia) published toprovide technical information/data for reference purposes only. By using this applicationnote, the user agrees to the following: This application note has been prepared solely for reference on the subject matters
incorporated within it and Nichia makes no guarantee that customers will see the same
results for their chosen application.
 The information/data contained herein are only typical examples of performances and/or
applications for the product. Nichia does not provide any guarantees or grant any licenseunder or immunity from any intellectual property rights or other rights held by Nichia or
third parties.
 Nichia makes no representation or warranty, express or implied, as to the accuracy,completeness or usefulness of any information contained herein. In addition, Nichia shallnot be liable for any damages or losses arising out of exploiting, using, or downloadingor otherwise this document, or any other acts associated with this document.
 The content of this application note may be changed without any prior or subsequent
notice.
 Copyrights and all other rights regarding the content of this document are reserved by
Nichia or the right holders who have permitted Nichia to use the content. Without priorwritten consent of Nichia, republication, reproduction, and/or redistribution of thecontent of this document in any form or by any means, whether in whole or in part,
including modifications or derivative works hereof, is strictly prohibited.

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TOKUSHIMA 774-8601, JAPAN
Phone: +81-884-22-2311 Fax: +81-884-21-0148

NICHIA CORPORATION
http://www.nichia.co.jp

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