Selecting Cold Cathode Fluorescent Lamp (CCFL)--LCD Backlight
The CCFL (Cold Cathode Fluorescent Lamp) is a light source classified as an electronic component. The CCFL in simplest ter is a gas-discharge light source, which produces its output from a stimulated phosphor coating inside the glass lamp envelope. A CCFL can be described as a transducer converting electrical energy into light energy.
The Silver Reflector is sputter-coated Ag on polyester film with outstanding optical, mechanical and thermal properties
LCD Backlight Unit
The CCFL or backlight Lamp is mount in side a reflector., an example of a notebook one is shown below, but on some other units there may be up to 4 lamps inside a multiple reflector
Reflector that normally holds the tube inside it, be careful when removing the old tube
How to select the LCD Backlight:
Backlights or ccfl tubes come in various lengths, and the length varies on various brands of lcd.
As an example, the 15" lcd may use between 260-330mm the best way to select a backlight is to measure the one that you presently have
There are three main ways to select the right lamp, which are below.
You need to get as close as you can but not going longer than the one you have (they don't squash down) generally you can get away with between 2-10mm shorter than the original lamp without affecting the quality of the light you receive. even with one slightly shorter, you would only have a tiny slightly less bright corner just below the lamp, but it would still be perfectly usable.
Remember if you select one to long, you will not be able to install it.
How to Measure the Length of LCD Backlight
Method 1: Direct Measure:
This is the best way to get the closed length of lamp possible.
Carefully remove CCFL from Backlight reflector
Slowly pull out rubber cap as show in the picture below
Measure the length of CCFL lamp, Selected the length slightly shorter
For Example: Your old lamp measurement is 320mm, You should use the length of 316mm
Showing the ccfl backlight with the rubber insulator , or cap removed with the pin showing
LCD Backlight (CCFL Lamps) are normally held on inside of Reflector as picture shown at below.
There are Silicone Rubber Cap on both ends of CCFL Lamps.
The measurement should be from glass to glass( Shown on Photo below) plus the length of one of Silicon Rubber Cap.
For Example: The measurement from glass to glass is 310mm, your Rubber Cap measurement is 5mm (Only Measure one of caps),
Then you correct length should be glass to glass plus 4-5mm one end. Let use 5mm for example.
So, the correct length should be 315mm+5mm = 320mm. Selected the length slightly shorter then your measurement
Active area Measurement for Laptop Screen:
It is not a good idea to pull your old lamp out from your laptop screen, measuring it and waiting for new lamp to arrive.
So there is another effective way by measuring the active area of screen, horizontally as shown on photo below.
Then you can do that all the replacement at once.
Measure the active area width (View Area) (measurement active) from left to right (Horizontally), add between 2-5mm to the length
Example: Active area is 272mm; you should use 275mm (or the one slightly below if exact size is not available)
Note: This method is base on CCFL is mounted either on the top or bottom (Horizontally) Not all baclights are mounted horizontally, if it is a vertical one, measure vertically