The emergence of Japanese new technology LED eyelashes has aroused everyone's attention. This eyelash not only shines but also follows music and dance. So the question is, what is the technical principle of this lash eyelash? Will it be harmful to the human body after a long time?
Japan develops new technology LED eyelashes eventAccording to Japanese media ITmedia, Ritsumeikan University of Japan has developed an LED "lighting false eyelash" that does not require batteries and wires, and can follow the music melody.
Originally, this was jointly developed by Ritsumeikan University of Japan and Shiseido of Japan Cosmetics Co., Ltd., which is a small electric receiver that is composed of a fiber with a diameter of 1 mm and a length of 3 cm, and an antenna.
It is placed on the false eyelashes and then wirelessly delivers power to the receiver, with a radio transmission interval of up to 1.5 meters and a power of 10 watts.
The intensity of the emitted electromagnetic waves is controlled within the scope permitted by the Japanese government, thereby ensuring that the false eyelashes "illuminate" without using batteries and wires. The researchers said that wearing these lights would not have any adverse effects.
What is the principle of Japanese LED eyelashes?Through the description of the event, we can see several important technical keywords, that is, without a battery and wire, as long as a 1.5-meter radio transmission, is it really magical? What is the principle of his radiance? Is the intensity of microwave harmful to the human body? We will answer these questions one by one to see if you can use this magic eyelash.
1.5 m radio transmission
The 1.5-meter radio transmission can illuminate, so what is the principle of radio transmission? How far can the distance of radio transmission be reached? How to calculate, let's take a look:
Radio transmission principle
The wireless power supply technology that has been introduced now can be roughly divided into three categories according to its power transmission principle:
The first category is the principle of electromagnetic induction used in contactless charging technology. This non-contact charging technology is increasingly used in many portable terminals. In this type, two coils are placed in adjacent positions, and when current flows in one coil, the generated magnetic flux becomes a medium, causing an electromotive force to also be generated in the other coil.
Both theory and experience have shown that when the primary side current frequency and amplitude are higher, the distance between the primary and secondary sides is smaller, and the relative magnetic permeability of the medium around the core is higher than that of air.
When large, the transmission efficiency of the separable transformer is higher. However, in practice, the distance between the primary and secondary sides cannot be infinitely small, and corresponding compensation measures must be taken for the primary and secondary sides.
The second category is the closest to practical application, which directly applies the principle that electromagnetic energy can be transmitted and received through an antenna. Microwave energy transmission means that the microwave is focused and then directionally emitted, and the received microwave energy is converted into direct current energy through a rectifying antenna (rect2enna) at the receiving end.
This is basically the same as the radio principle 100 years ago: the AC waveform of the radio wave is directly converted into DC after the rectifier circuit, but the amplifier circuit is not used. The efficiency of this technology has been improved compared to the past and is driving manufacturers to put it into practical use.
The third type is a resonance method using an electromagnetic field. Resonance technology is widely used in the field of electronics. However, in the power supply technology, electromagnetic waves or currents are not used, but only electric or magnetic fields are used. In November 2006, the research team of Marin Soljacic, an assistant professor of physics at the Massachusetts Institute of Technology (MIT), announced for the first time the possibility of applying electric or magnetic fields to power supply technology.
Distance calculation for radio transmission
The line transmission distance can be calculated by itself.
Line transmission distance calculation: Pr(dBm) = Pt(dBm) - Ct(dB) + Gt(dB) - FL(dB) + Gr(dB) - Cr(dB)
Pr: Receiver sensitivity Pt: Transmitter power
Cr: Receiver connector and cable loss
Ct: Transmitter connector and cable loss
Gr: Receiver antenna gain
Gt: Transmitter antenna gain
FL: free space loss
FL(dB)=20 lg R (km) +20 lg f (GHz) + 92.44
R is the distance between two points f is the frequency = 2.4
Harmfulness is certain, but the degree is very different. Modern society cannot completely avoid microwave radiation, and can only control the dose and frequency as much as possible. So let's take a look at the extent of the damage to the eye and the case of the microwave.
Regarding the damage of microwaves to the eyes, there have been a lot of reports in the country, whether it is epidemiological investigations of occupational exposure populations or animal experiments. Many reports suggest that high-intensity microwave irradiation produces cataract [770], and animal experiments have been reported [17,20-23], but the chronic effects of low-intensity microwaves can cause eye damage (especially lens opacity and cataract). Conclusion [15-18, 20, 24].
The biological effects of microwaves have both pyrogenic and non-pyrogenic effects, which are harmful to various systems of the human body, and the lens of the eye is the main target organ [19]. It is generally believed that since the lens itself has no vascular tissue, it becomes a sensitive part of the microwave causing thermal damage. However, there is no known clinically specific morphological features of cataract caused by microwave, so it is controversial to determine the clinical human microscopic cataract [15,25].
It has been reported that long-term work in a certain intensity microwave environment can make the lens of the eye turbid, dense, vacuolar degeneration, and related to contact time. There are no regularities in the opacity and location of the lens. The morphology is punctate, flaky, strip-like, reticular, crust-like, etc. The posterior sac, posterior inferior cortex, posterior pole, equator and anterior cortex are located [15-17, 19, 25-29, 33]. In addition, microwaves also cause damage to other parts of the eye such as the conjunctiva, cornea, iris, fundus, etc., including fatigue [19,30, 31], decreased vision [15,16,24,32,33], conjunctival hyperemia [20 , 33], corneal damage [33], grayish brown spots appear in the macular area of ​​the retina [21,29,34], old lesions in the macular area [27], weak response to light [20,33], small blood vessels in the fundus, bleeding [17,26], retinal fine bleeding points [19, 21, 33, 34,] and so on.
Dai Shufang et al. (1994) reported on a survey of 142 radar operators with a microwave power density of 100-300 mw/cm2. The results showed that the incidence of lens opacity in the microwave contact group (76.05%) was significantly higher than that in the control group (48.78%). The turbidity of the two groups was also significantly different. The turbidity pattern was mostly punctate, flaky, and opacity. (Compared with 6 years ago) there are also big differences. There was no significant difference in the fundus-changing contact group compared with the control group, and no abnormal changes were found in the optic disc, cornea, and iris [29].
The Sichuan Medical Vocational College (1982) reported on 296 occupational contacts, with a microwave power density of 10-100 mw/cm2. The results showed that the incidence of visual loss in the microwave group (32.65%) was significantly higher than that of the control group (15.75%). ), the incidence of more than 4 turbid granules in the posterior cortex, equator, anterior cortex and posterior pole of the lens was found to increase to a different extent compared with the control group, mainly as fine dusty turbidity, and the degree of turbidity in both eyes was similar [ 16].
Pan Dayan et al. (1992) reported a health impact survey of 33 microwave room workers exposed to microwave power density of 75-175 mw/cm2. The conjunctival hyperemia, the reduction of fundus macular area and the detection of lens opacity (76.4) were found. %, 21.1%, 27.3%) were significantly higher than the control group (9.8%, 2.4%, 9.8%), but no cataract was found [20].
In addition, there are some reports that low-intensity microwave irradiation has no obvious effect on the eye. Zhou Congqin et al. (1981) investigated 251 radar personnel in the warships, and their contact microwave power density was 0-35 mw/cm2 and 77000 mw/cm2. The results showed that there was no significant change in visual acuity, visual field, lens, and fundus in the contact group [30]. Li Huanying et al. (1993) investigated 144 microwave communication personnel with a power density of 10-450 mw/cm2 in contact with microwaves, 14 cases (9.72%) of 144 people with varying degrees of lens opacity, and 86 patients in the control group. There were 12 cases (6.97%), and there was no significant difference between the two groups by c 2 test [36].
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