The optimum ambient temperature range for the highest efficiency and brightness is 77 to 104☏ (25 to 40☌). However, when many CCFLs, more than 4, are used together in an enclosed panel, overall heat dissipation should be taken into account. Most LCDs in the embedded market use 4 tubes or less. The heat is spread over the surface area of the tube using heat dissipation. CCFLs typically have low heat generation, about 6 - 8 watts per tube. In many LCD panels, the CCFLs may be replaced when they reach the end of their useful life. The color temperature of the tube doesn’t usually change as the bulb gets older. Increasing the current will decrease the life expectancy, but will increase the brightness. The useful life for all backlights is defined by when the light output from the tube reaches half of its initial brightness. Rather, the tube slowly dims over time due to phosphor erosion.
CCFLs rarely exhibit catastrophic failure unlike incandescent bulbs. The life expectancy of CCFLs used as backlights is now around 50,000 - 60,000 hours. The inverter switch has built-in protection so that if the tube does not strike after it’s gotten a few hundred volts more than the normal strike voltage, the tube is considered dead. Using this example, the power draw would then be 4.8 watts. For example, a CCFL may have a strike voltage of approximately 1200 V, an operating voltage of approximately 800 V, and an operating current of 6 mA. After the tube strikes which is identified by current flowing, the inverter then drops the voltage until the rated current is flowing which is typically around 5 to 7 mA. The strike voltage may be several hundred volts higher than the sustaining voltage, just to get the CCFL to light up. When power is applied to the inverter, it starts by ramping up the output voltage until the CCFL turns on (an arc strikes). The inverter has to be matched to the specifications of the CCFL, particularly the current, strike voltage, and operating voltage. The inverter that’s designed to power an LCD CCFL will typically run at about 50 kHz. Also, the strike voltage or the voltage required to start the light of the CCFL is different than the sustaining voltage. In addition, CCFL backlights require constant current, not constant voltage.
An inverter is typically used to create the high-voltage AC.
Most systems that have LCD panels run on direct current (DC), the DC has to be converted to AC in order to power the lamp. Typically, the resulting temperature color is in the 2800 - 3200K range, which looks like a warm to standard white light. The phosphorus make-up determines the color temperature of the visible light output. The ultraviolet energy excites the phosphorescent lining which then produces light in the visible range (400 to 700 nm). When the high voltage is applied the resulting arc ionizes the internal noble gas which produces ultraviolet energy. The tube is then sealed at both ends with an iron-nickel electrode located at each end of the tube.ĬCFLs operate on high-voltage alternating current (AC). These backlights usually have a hollow glass cylinder - 2 to 10 mm in diameter, that’s internally coated with a phosphorescent material and filled with a noble gas (most commonly argon).
Cathode light tube full#
This includes the full spectrum of white lamps commonly used in various LCD screens as well as specialty color, UV, and infrared lamps that are used in a wide range of applications.ĬCFLs have been used for years as a backlight source. We also specialize in precision color-matching technology and use the latest in testing equipment that allows us to both analyze and produce any color CCFL backlight you want. In short, if you don't find the perfect solution for your LCD backlighting needs on our website, or, just give us a call or send us an email with your specific needs.
Some of the CCFL backlight shapes Plazmo offers are: C, U, L, and M shape lamps. We make new, specialty backlight lamps for any and all LCD applications, including straight and shaped lamps. If you have an old, obsolete LCD or even a new, yet uncommon, LCD requiring a specific or custom-made backlight, we can help. We can make any type of CCFL backlight you might need. In addition to our standard CCFL backlight offerings, we have complete engineering and manufacturing capabilities for custom designs. We also have more than 200,000 complete LCD backlight assemblies in stock in addition to the millions of CCFL backlights Plazmo has in stock. The CCFL products we carry consist of hundreds of different sizes of raw Cold Cathode Fluorescent Lamps (CCFLs) available in diameters from 1.8mm - 6.0mm, and lengths from 40mm all the way up to 1,400mm. We currently have more than 1 million CCFL backlights in stock and ready to ship. Plazmo is the largest supplier of CCFL backlights (Cold Cathode Fluorescent Lamp) in North America.
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