Where other forms of energy can be converted into light energy, which provides the luminous flux of equipment, appliances collectively referred to as light; and which can be converted into light energy, which provides the luminous flux of equipment, equipment is called electric light source. (Such as fluorescent lamps, mercury lamps, sodium lamps, metal halide lamps, etc.); ③ solid light emitting light source (such as fluorescent lamps, mercury lamps, sodium lamps, metal halide lamps, etc.); ③ solid light emitting light source (such as incandescent, halogen, etc.) (Such as LEDs and electroluminescent devices, etc.). In these three types of electric light source, a variety of electric light source luminous efficiency is quite different, thermally induced light source such as incandescent lamp, which uses Stephen - Boltzmann law: the higher the object temperature, it radiated the energy Big. This can be expressed by the formula E = μξT4. Where E is the total energy of the radiation per unit area and unit time at the temperature T; μ represents the Stephen-Boltzmann constant (μ = 5.6697 × 10-12W / (cm2 · K4)); ξ represents the radiation Rate, that is, the object surface radiation and black body radiation ability ratio; T that the absolute temperature of the object. The use of thermoluminescence principle made of electric light source is simple and low cost, but the luminous efficiency is low, the rest of the energy is consumed in the form of heat.
Incandescent lamp luminous efficiency is generally 7 ~ 20lm / W, luminous efficiency of only 11%, infrared, heat energy consumption accounted for 69%, 20%; most of the energy loss of heat. The luminous efficiency of gas discharge light emitting devices such as Florescent, Halide, and HID is much higher than that of thermal radiation, and their luminous efficiency is normal. Incandescent lamp several times, under normal circumstances, you can gradually use high luminous efficiency of the gas discharge electric light source instead of thermal radiation light source.
As the gas discharge lamp power can be done larger (several kilowatts), luminous efficiency is high, is a green lighting electric light source. Commonly used light source classification shown in Figure 1.
As the gas discharge lamp light source in the lamp luminous efficiency and working life with incandescent unparalleled advantages, therefore, from its birth date has been subject to widespread concern, which derived products can be described as colorful. At present, the market has about 5000 kinds of electric light source. Thermal radiation light source to ordinary incandescent bulbs and halogen tungsten series of light bulbs as the representative. Gas discharge electric light source, mainly refers to the arc discharge electric light source and glow discharge electric light source, such as fluorescent lamps, high-intensity gas discharge lamps and neon lights. Arc discharge electric light source can be divided into low-pressure discharge electric light source and high-intensity discharge electric light source.
Low-pressure gas discharge electric light source to fluorescent lamps and energy-saving lamps as the representative; high-intensity gas discharge electric light source to high-pressure mercury fluorescent lamps, high pressure sodium lamp (abroad also low pressure sodium lamp) and metal halide lamp as the representative. For example, the luminous efficiency of high pressure sodium lamp is 8 ~ 10 times the incandescent lamp, long life, stable characteristics, high luminous flux maintenance rate, suitable for color in the less demanding roads, squares, docks and indoor tall factories, warehouses, etc. Place of lighting applications.
Metal halide lamp, with high luminous efficiency, good color, power characteristics, suitable for theater, assembly shop and other large area lighting applications.
Single-ended compact fluorescent lamp luminous efficiency of 50lm / W. Using a 9W, life of 3000 ~ 5000h energy-saving lamps can replace 40W incandescent bulbs; double-ended straight tube T12 fluorescent lamp luminous efficiency of 55lm / W, life of 3000 ~ 5000h, and now the T5 fluorescent light Efficiency up to 90 ~ 110lm / W, life of up to 8000 ~ 10000h.
In recent years, many other types of new light sources have been developed and developed, such as excimer light sources (ELS), microwave light sources and solid light sources (such as LEDs). Solid light-emitting devices, such as light-emitting diodes, plasma light-emitting devices, etc., despite their high luminous efficiency, can not get high power (such as hundreds of watts), so solid-state light-emitting devices to enter the large-scale practical stage there is a distance, According to the analysis in the past 10 years, the traditional electric light source will be the mainstream (such as incandescent and fluorescent lamps, etc.).
(1) Gas discharge discharge light source by discharge form
① Arc discharge lamp. This type of gas discharge electric light source mainly uses the arc discharge column to produce light. Cathode work at higher temperatures, so also called hot cathode lamp. This type of gas discharge electric light source usually need special start devices and lines to work, electric light mainly fluorescent lamps, mercury lamps, sodium lamps and so on.
②Glow discharge lamp. This kind of gas discharge electric light source from the glow discharge column to produce light, the cathode temperature is not high discharge, so called cold cathode gas discharge electric light source. Anode to cathode voltage drop (100V or so), the current density is small. Neon is of this type.
(2) By the discharge of the current through the media division
① Gas discharge lamp. The use of gas discharge light. Such as xenon lamp, fluorescent lamp and neon lamp.
② Metal vapor lamp. The use of metal vapor (such as mercury vapor, sodium vapor, etc.) to produce light, such as mercury lamps, sodium lamps and so on.
(3) According to the level of atmospheric pressure during discharge
① Low pressure light. Discharge, the lamp pressure is about 1% of the atmospheric pressure, such as fluorescent lamps, low pressure sodium lamps and so on.
② High pressure light. Discharge, the lamp pressure of 1 to 5 atmospheric pressure, such as high pressure mercury lamp, high pressure sodium lamp, high pressure xenon lamp and so on.
③ Ultra-high pressure light. Discharge, the lamp pressure is greater than 10 atmospheric pressure, such as dysprosium lamp, scandium sodium lamp, sodium scandium smoke and so on.
The luminous efficiency of high pressure mercury lamp up to 50lm / W, color rendering index Ra over 65, color temperature 4000 ~ 6000K, life can reach about 10000h, power specifications 35 ~ 3500W, has formed a series. High pressure sodium lamp luminous efficiency of 120lm / W, color rendering index Ra is 25, life reaches 24000h, power specifications are 30 ~ 1000W. HID lamp heat is only half of the halogen, lamp life of up to 2500h or more.
Fluorescent lamps are 70% more energy efficient than incandescent, and are suitable for indoor lighting applications such as workshops, dorms and roof spaces less than 5m. Compact fluorescent lamps have a luminous efficiency of 5% higher than that of conventional fluorescent lamps. Tubular fluorescent lamps are 10% more energy efficient than conventional fluorescent lamps. Therefore, compact and thin tube fluorescent lamps are energy efficient electric light sources introduced in today's "green lighting project".