Principle and Classification of Illuminance Meters How Illuminance Meters Work
Illuminance meter measurement principle: Photocell is a photoelectric element that directly converts light energy into electrical energy. When the light to the surface of the selenium photovoltaic cell, the incident light through the metal film 4 to the semiconductor selenium layer 2 and the metal film 4 on the dividing surface, in the interface to produce photoelectric effect. The size of the potential difference generated is proportional to the illuminance on the light-receiving surface of the photocell. At this point, if an external circuit is connected, a current passes through, and the value of the current is indicated from a microampere meter graduated in lux (Lx). The magnitude of the photocurrent depends on the intensity of the incident light and the resistance in the circuit. The illuminance meter has a variable speed device, so that it can measure high illuminance as well as low illuminance.
Illumination is closely related to people's lives. Adequate light can prevent people from accidents. On the contrary, too dark light can cause human fatigue far more than the eyes themselves.
Unsuitable or poor lighting conditions are therefore one of the main causes of accidents and fatigue. Available statistics show that about 30% of all accidents in occupational labor are directly or indirectly caused by insufficient light.
The light requirements for stadiums (halls) are very strict, too much light or too dark will affect the effect of the game.
So, people live in the room on the illumination of hygiene requirements are how? Illumination is a very important indicator in hygiene. Light refers to electromagnetic radiation that can cause the human eye light feeling, when the light enters the eye can produce the perception called vision. The light that people see is visible light, whose wavelength ranges from 380 to 760 nm (nanometers).
Lighting can be divided into two categories: natural lighting and artificial light sources. Natural lighting refers to the indoor and regional natural illumination, direct sunlight scattered light and reflected light from surrounding objects, commonly used lighting coefficient and natural illumination. The lighting coefficient refers to the effective area of the light port and the ratio of indoor ground area.
General residential lighting coefficient between 1/5 ~ 1/15, living area ratio between 1/8 ~ 1/10 (window area / indoor floor area). The natural illumination coefficient is used to evaluate the level of illumination from natural light. It is a reflection of the relationship between indoor and simultaneous light exposure from the outdoors. It also reflects the local light climate (the sum of sunlight illuminance indicators of natural light energy and climate).
In order to ensure that people live in the appropriate light, China has developed a health standard on indoor (including public places) illumination. Such as shopping malls in public places (store) illumination health standards ≥ 100Lx; libraries, museums, art galleries, exhibition halls countertops illumination health standards ≥ 100Lx; public bathrooms illumination health standards ≥ 50Lx; bathrooms (showers, pools, bathtubs) ≥ 30Lx, sauna ≥ 30Lx.
Foreign standards for indoor illumination, such as Germany recommended several rated light intensity, office, including clerical workspace for 300Lx, typing, drawing work for 750Lx; in factories, production lines, the visual work of the illumination requirements for the 1000Lx; hotels, public rooms for 200Lx; reception points, cashier cabinets for 200Lx; store windows for 1500 ~ 2000Lx; hospitals 150~200Lx for wards and 500Lx for emergency treatment areas; 400~700Lx for schools and classrooms; 300Lx for cafeterias and indoor gyms, etc.
For the measurement of the size of the illuminance, generally measured by illuminance meter. Illuminance meter can measure the intensity of different wavelengths (such as the visible light band and ultraviolet band measurement), can provide people with accurate measurement results.
