With the continuous development of science and technology, currently commercialized lighting products from the first generation of incandescent lamps; Second generation fluorescent lamp, halogen lamp; The third generation of high-intensity gas discharge lamps and the current mainstream fourth generation of light-emitting diodes (leds). The light efficiency of lighting lamps and lanterns is getting higher and higher, and has been developing towards energy conservation and environmental protection. However, there is no denying the fact that the development of electric light source also brought a lot of new problems, in addition to the impact on the environment, energy and so on, the effects of artificial lighting environment on human health is also nots allow to ignore. Nowadays, people not only pay attention to the physical properties of lighting, but also attach great importance to the light biosafety of lighting. And the commercialization of electric light source lighting products most are driven by ac, lamps and lanterns of stroboscopic effect to human body health has become the influence of all kinds of lighting products need to focus on the problem.
Kang Lisheng net. Notice: reading and writing assignment desk lamp is People's Daily study, work and strengthen the lighting, computer operations due to the long time use, has become the most closely contact with the human daily activities of one of the lighting products. Also includes a large number of and in the use of the crowd at puberty teenager, speaking, reading and writing assignment desk lamp of stroboscopic effect is also one of the important factors that induce juvenile myopia, so in recent years "no stroboscopic" appeared on the market "the desk lamp that shield an eye". Due to the desk lamp that shield an eye "without strict scientific reasoning and impartial third party testing, and are used to verify the rotation of the stroboscopic gyro method is very rough, can't get accurate results of quantitative, so this kind of 'the desk lamp that shield an eye" is unscientific.
To sum up, research, speaking, reading and writing assignment desk lamp of stroboscopic effect for deep understanding stroboscopic mechanism, reduce the reading and writing desk lamp lighting effects on the human body, build an efficient environmental protection, safe and reliable, lighting environment is good for people's work and life has very important significance.
Flicker and strobe
The definition of flicker in the ninth edition of the illumination manual published by the north American illuminating society (IESNA) is the rapid change in the intensity of the light source. For lighting products, whether the traditional light source or the current LED lamps, as long as it is driven by communication, the work will produce flicker. The representation of scintillation degree is mainly concerned with the frequency of communication and the continuity and observation condition of light source. Scintillation has a significant effect on the moving objects in the range of observation, and the object may appear discrete state rather than continuous in the flashing light. This effect is called the stroboscopic effect. The stroboscopic effect depends on the speed and amplitude of the flicker, as well as the speed and state of the motion of the object.
IESNA lighting experts have proposed to use scintillation percentage and scintillation index to represent the stroboscopic characteristics of lighting. The calculation method of both is shown in figure 1.
The difference between the two measures is that the scintillation percentage is only the ratio of peak to peak. The scintillation index can well in this paper, the differences between the output waveform, mathematical representation is also more accurate, but less people know the scintillation index, and lighting are rarely found in the literature research was made, part of the reason may be because the scintillation index need complicated mathematical integral and accurate collection of relevant waveform. In view of this, the current frequency flicker evaluation parameter of general selection flicker percentage is also called wave depth. The fluctuation depth is in the periodic light output waveform, the difference between the maximum value and the minimum value of the optical output in a period is the proportion of the sum of the maximum and the minimum value, expressed as a percentage.
With regard to flicker and frequency flicker, there is no relevant standard in China, and only the requirement of flicker is considered in the CQC voluntary certification technical specification, the technical specification for visual work lamp certification. For the measurement of stroboscopic, internationally is controversial, there is no uniform an effective quantitative analysis method, the concept of wave depth has is the study of stroboscopic a stride. IEEE issued IEEE par1789 "the potential health impact of LED lighting" (draft), which used wave depth to assess the stroboscopic effect.
Stroboscopic photobiological hazards.
The harmful effects of light on human health are a long-term and chronic accumulation process, and the developed countries in the world have started relevant researches very early. According to different factors, such as the flicker frequency of light and intensity of light intensity, the harm of light to human body is different. At present, the results of the study have found that the adverse physiological reactions caused by stroboscopic effect include:
(1) headache and eye strain.
Dr Wilkins and others found that office workers with high frequency electronic ballast fluorescent lighting lamps and lanterns than with 50 hz ballast decreased the number of headaches beep twice according to the report of the national headache foundation | | : "many people with migraines are very sensitive to light, such as light and flashing, are more likely to lead to migraine. Slow flickers are usually more likely to cause migraines than rapid flashes. "Some fluorescent lighting or flickering from TV or movie screens has a similar effect."
(2) photosensitive epilepsy.
Light sensitive crowd within 3-70 hz under the visible light modulation of contact will be epileptic fit even for short periods of time, this will probably affect the 1/4000 people aged 5 to 24, usually around puberty onset, and 75% of the population will be a lifelong is sensitive to light.
(3) impaired vision
Veitch and McColl discovered in 1995 that compared to high frequency electronic ballasts, the 100-120hz modulation of the electrosensory ballast fluorescent lamp system would reduce the average vision of the group. This often occurs in text reading and text reading on a computer screen.
The eyes of the eye are more sensitive to the flash, such as the flashing lights or the rapid modulation of the car's taillights that will attract the driver's gaze. Moving your eyes away in advance may be dangerous for drivers or people and things on the road. The frequency flash source that combines with the machine in operation produces an opening and closing effect, which can cause significant difference in movement and stopping speed. It was identified in the industry a decade ago.
Children with autism are particularly sensitive to changes in the environment, and the frequency flicker in lighting increases the recurrence of this behavior, which is about one in 110 children in the United States.
Human body is exposed to a stroboscopic lighting environment, easier to produce adverse reaction conditions are as follows: contact time is long, area is large, field orientation on the retina to stimuli center, flash high brightness, high brightness contrast with the environment, deep red in colour.