It therefore becomes apparent the use of modern energy-saving lighting. But, unfortunately, modern lighting systems have their drawbacks:
1. The rather high price,
2. Lack of proper use experience,
3. A large number of defective products,
4. Parameters of the light sources do not meet the standard documentation,
5. Elevated pulsation of light. Let’s consider how the ripple of light effects on the human body.
Pity but most manufacturers and lighting engineers disregard the rules and requirements of the lighting systems. Thus, even in the middle of the twentieth century, there have been studies showing susceptibility of human brain to pulsations of luminous flux at a frequency of 300 Hz.
For example, the work of I.Oshurkov „Standards-based approach to the pulsation of LED lighting“ shows an electroencephalogram (EEG) of the human brain (Fig. 1), from which it is clear that the impact of the pulsating light flux causes imposed activity peaks with the frequency of the pulsations of light flow. Such imposed peaks provoke suppression of natural biorhythms of the nervous system (in the example considered pulsation frequency of the light flux, equal to 120 Hz).
Fig. 1. EEG of the human brain: a) the room is darkened, b) a room lit by lights that pulsate with a frequency of 120 Hz.
During the experiment it was determined:
a) ripple luminous flux equal to 5-8% show signs of the emergence of brain disorders with normal electrical activity;
b) starting with the ripple level of the luminous flux equal to 20% of the disorder occurs with normal brain electrical activity, as at 100%.
Also that was experimentally determined the critical frequency of the pulsations of the luminous flux of 300 Hz when the human eye sees a pulsating light output as continuous. Data similar to those described above, as shown in Wilkins AJ „Fluorescent lighting headaches and eye-strain“. It was noted that visible light flow pulsations with a frequency of 60-80 Hz and invisible at a frequency of 60-80 Hz and 300 may act differently. Pulsations which the eye perceives, can provoke irritation of the optic nerve, i.e. people feel discomfort that causes fatigue of the nervous system and the brain. Thus, a person consciously or subconsciously trying to eliminate discomfort, reduces time spent indoors with pulsating light flux, trying not to take such vision and brain pulsations, or just change the lamp or lamps that do not produce ripples. I.e. visible pulsations person is able to feel and deal with them.
The human eye is visually perceives the pulsation ceases light flux, depending on individual characteristics, since the range of frequencies above 60-80 Hz. This frequency is the critical flicker fusion frequency. Thus, the human brain is able to process information about how to change the light intensity. Wherein the eye perceives such pulsations but does not process them as visual information, so these pulsations act directly on the human brain. As a result of the harmful effect of high-frequency fluctuations of the light flux may negatively affect the hormonal background, daily biorhythms, efficiency, fatigue, emotional well-being. Prolonged exposure to light flux fluctuations can lead to a variety of chronic diseases ranging from eye diseases, cardiovascular and the nervous system diseases. All of the above shows how important it is to comply with requirements for the level of light flux pulsations in modern light sources. Currently, medical professionals are discussing the problem of insufficient control on the ripple of light and develop new standards for quality lighting.
How to empirically measure the luminous flux pulsations in modern fixtures and lamps in world practice, there are examples of both successful and unsuccessful use of modern lighting systems. Here are some examples where we show that modern lighting in terms of technology is still in early development. This is what causes the market presence of the set of „raw“ solutions, defects and fakes. Nevertheless, these problems are easily solved, most importantly before the end of the project on lighting calculation and testing solutions conceived to directly localize and eliminate potential problems.
For example, the pulsation of the light flux of the new lamp indicates unscrupulous manufacturers saving in production, because to ensure low ripple additional investments are necessary. Thus, we can safely assume that this manufacturer will save on other parameters, which further lead to poor performance of the product: the lifetime, energy, color, electromagnetic compatibility, overload protection, power surges, etc. But there are real life examples that show how to determine the levels of pulsation of the light flux, their causes and how to eliminate defects.
First example: One of the expensive „smart“ lighting systems manufacturer of widely known foreign brand saw that intermediate levels of brightness caused increased ripple. Measurements were made using „ECOlight-AP“ program, revealed that the PWM modulator with frequency of 200 Hz controls the brightness of the lamp. Based on the results of measurements the manufacturer increased the frequency of the PWM controller to 1 kHz. In all ranges of brightness decreased pulsation of the luminous flux of lamps at the level less than 1%.
Second example: Fixtures „Armstrong“ for ceilings, gas discharge lamps 4 * 18 Watts and EMPRA. Checkpoint illuminance is 450 lx, ripple luminous flux is 40%. After the replacement of lamps on those having a color rendering index Ra> 90, and a high-quality electronic ballast class A2 instead EMPRA, were able to increase the illumination of the control point up to 1100 lux, the pulsation was reduced to 0.5%, power consumption remained unchanged. The cost of this upgrade was minimal.
Widespread use of lighting systems can improve the comfort level of people’s lives. At this stage, all the problems of the use of light sources are solved. Now LED, compact discharge, induction lamp types are widely used, and further their operation will be as simple as screwing in a new bulb. In any case, the choice of the light source should be approached carefully.