Lighting powder technology affects light decay

Friends who have used lighting for a period of time know that long service life and excellent luminous maintenance performance are a significant advantage of lighting. Why does lighting have such good luminous maintenance performance? For lighting, there are no traditional filaments and electrodes in the lamp tube. The high-frequency ballast of the application specific integrated circuit emits high-frequency radio wave energy. Through electromagnetic induction measures, a magnetic ring with a coil is used to set the height outside the lamp tube. The high-frequency electric wave energy is coupled into the discharge lamp tube filled with mixed inert gas and special amalgam. Because the high frequency reaches 210KHz, the electron movement in the lamp tube ionizes and excites the amalgam molecules, generating 253.7nm ultraviolet photons, which hit On the inner wall of the glass bulb coated with rare earth phosphor, visible light is generated. During the ignition process of traditional light sources with filaments and electric grades, the electron emission material continuously splashes out of the electrodes, and the splashing during the start-up process is particularly intense. The emitted luminous flux gradually decreases. The luminous flux drops extremely fast in the first 100 hours. When the electron emitting material on the electrode is exhausted, or the remaining coating on the electrode cannot continue to emit electrons, the lamp cannot continue to burn. When the traditional light source is started, the electron emitting material loses a lot, so the more frequent the start, the shorter the life span. When the power supply voltage increases, the current of the lamp increases, and the evaporation of the electron emitting material is accelerated due to the overheating of the electrode, and the life is shortened. When the power supply voltage decreases, the current decreases, the electrode temperature is insufficient, and the start-up is difficult, which promotes the scattering of electron emission materials, which increases the light attenuation and shortens the life. Light decay mechanism of lighting: For lighting tubes, if the traditional organic coating liquid powder is used, the main reason for the light decay is that the nitrocellulose binder in the powder layer after the pre-formed glass tube cannot be completely baked in the baking stage. Exhaust, this will result in the formation of a black light-absorbing film of carbon and mercury oxide on the inner surface of the phosphor layer, making the powder layer colored (black); the second reason for the light decay is the high sodium content of the glass tube produced in China , And the light-induced degradation is severe. During the life of the lamp, mercury will penetrate into the glass, and the sodium in the glass will diffuse to the powder layer, and combine with mercury to form a black sodium amalgam, which will pollute the phosphor particles; third The reason is that the quality of the phosphor itself is not high, there are impurities on the surface, and it is easy to adsorb mercury oxide and mercury. The key technology of lighting to overcome the luminous decay of the lamp: In view of the main reasons that the luminous lamp is prone to luminous decay, in addition to the use of perfect crystal, complete crystal, smooth and clean surface, no impurity phase, and uniform particle size, ball-free rare earth phosphor The following process technologies are used to reduce the light attenuation of the lamp: 1. The water slurry coating process with a new formula: For the rare earth three-base toner, a non-ionic polymer-polyethylene oxide is used as the water Temporary binder for slurry powder coating process. The binder has a relatively low decomposition temperature. It begins to decompose at 2000C. After reaching the decomposition temperature, it decomposes from the polymer into monomers, and these monomers run away in a gaseous manner. Therefore, the use of polyethylene oxide as a temporary adhesive can ensure that the formed glass tube is completely baked out of the adhesive during the tube baking stage, and the glass tube is not deformed, which prevents the formation of a black light-absorbing film on the phosphor layer . 2. Adopting protective film technology: In order to prevent the blackening of the glass tube and the thermal diffusion of sodium ions in the glass to the phosphor layer, the protective film technology is used for high-tube wall-loaded lighting (tube inner diameter 10mm, current greater than 0.2A), That is, before applying powder, apply a layer of protective film. There are two types of protective film, one is a transparent oxide protective film; the other is a light-transmitting aluminum oxide protective film. Production practice has proved that both protective films have protective effects. After adopting the protective film technology, the glass tube is no longer blackened due to the infiltration of mercury, the phosphor is no longer 'colored' due to the generation of sodium amalgam on its surface, and the 2000h and 5000h lumen maintenance rates of the lamp are greatly improved. 3. Optimizing the baking tube, cathode coating and exhaust process: After using polyethylene oxide as the binder, the baking tube process specification of the powder tube should be formulated according to the thermal decomposition characteristics of the polyethylene oxide to obtain the best Binder-free powder layer. The exhaust should be matched with the pumping rate of the vacuum system to facilitate the formation of the barium tungstate intermediate layer. When exhausting, the baking temperature should be high, the time should be sufficient, and the purity of the inert gas should be high to ensure the lowest impurity gas pressure in the lamp tube and obtain good light decay characteristics.