Artificial lighting and research methods

Artificial lighting is the most important condition and means of expanding human activity. It allows

lengthen the active time of the day, work at night, in underground structures, during polar nights, etc.

Indoor artificial lighting is provided by luminaires for general and local lighting. The luminaire consists of an artificial light source (lamp) and lighting fixtures that perform the function of a light flux distributor , a protective function against excessive brightness; it protects the light source from pollution and mechanical damage, and also plays a certain aesthetic role.

For artificial lighting, electric and non-electric light sources are used; the latter include kerosene and carbide lamps and lanterns, gas lamps and candles (all of them are used in exceptional conditions – in case of accidents, in the field, etc.).

The most common are electric light sources – incandescent lamps and fluorescent lamps. Incandescent lamps belong to the light sources of thermal radiation, yellow-red rays predominate in their spectrum, which distorts the color perception. They are the most reliable light sources in connection with a simple circuit for their inclusion, and environmental conditions do not affect their operation. The main disadvantages of these lamps include a small light output (7-20 lumens per 1 W of energy) and high brightness. Halogen incandescent lamps with a tungsten-iodine cycle are more effective, their light output and service life are higher than ordinary incandescent lamps (30 lm / W for up to 8000 hours). Their spectrum is close to natural light, so they are used to illuminate public buildings (libraries, canteens, etc.).

In hospitals, fluorescent lamps are used mainly as artificial light sources, the spectrum of which is close to natural light, there are no shadows, glare, and thermal radiation, and the lighting is soft, uniform. Preference is given to lamps with a spectral composition that is closest to natural light, such as LCE (cold natural light), LDC (daylight with correct color rendering), LDC-UV (with the closest natural UV spectrum), LE (white fluorescent light) – one with improved color rendering) – optimal for residential and public buildings.

It is recommended to refrain from the use of lamps LB (luminescent white with a yellowish tint), LD (luminescent daylight with a bluish color of radiation), LTP (luminescent warm white) having a spectral composition not optimal for a hospitable environment.

For hospitals located in climatic zones I and II, the artificial light environment should to some extent compensate for the lack of patients in the open air. Therefore, artificial lighting sources must ensure the general biological effect of light, necessary for the prevention of light starvation, nosocomial infections , and for increasing the immunobiological reactivity of patients.

Luminous efficiency of fluorescent lamps is 3-4 times higher than incandescent lamps, so they are more economical. High brightness of the lamps (4000-8000 cd / m 2 ) requires the use of protective ar- Mathura. Their main disadvantages are the appearance of a stroboscopic effect, as well as pulsation of the light flux and noise during malfunction of chokes.

A lamp (incandescent or luminescent) as a light source is used only with lighting fixtures (shade, lampshade, solid, annular or grating diffuser) and is called a lamp. From the point of view of redistribution of luminous flux, luminaires of direct, reflected and scattered light are distinguished. Direct light fixtures direct at least 90% of the total luminous flux into the lower hemisphere (on the working surface). The reflected light fixtures direct the main part of the light flux (90%) upward. The scattered light fixtures distribute the luminous flux more or less evenly in both hemispheres. From a hygienic point of view, preference is given to the latter – to scattered light lamps from milk, opal or

tinted glass, which uniformly illuminate the room and do not create sharp shadows.

The degree of protection of the eye from the brightness of the filament is judged by the value of the protective angle of the reinforcement. It is a flat angle formed by a horizontal line through the filament of the lamp and a line from the filament to the lower edge of the fixture (Fig. 15).

The protective properties of the luminaire are the better, the greater its protective angle, which should be at least 30o.

There are general, local and combined artificial lighting In the general lighting system , there are two ways of placing fixtures: uniform and localized. With uniform illumination, lamps are installed without regard to the location of the equipment ; at localized – depending on the location of workplaces, which provides the necessary direction of the light flux and creates conditions for better illumination of workers’ surfaces. The system of combined lighting includes both general and local lighting with the help of lamps located on the working places. The best conditions are created with combined lighting, and in order for the illumination to be uniform, the general illumination on the working surface should create at least 10% of the combined lighting norm, but at least 150 lux with fluorescent lamps and at least 50 lux with incandescent lamps. Otherwise, there is a rapid fatigue of vision due to the need to constantly adapt to too sharply different illumination on the working surface and outside it.

local_offerevent_note August 24, 2019

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