LED luminous letter (or caption machine) adopts light emitting diode as lighting source. It is usually installed on the top of buildings or on wall surface in the shape of given letters or signs. LED luminous letter chooses high brightness LED chips and uses specific system to take control of the dynamic video of the letters or signs. The unique designed LED luminous letter surpasses the traditional outdoor advertisement in function. Its abundance colors make it much superior than traditional neon light and make break through in application variety. Meanwhile, the power-saving trait and long life-span of LED reduce maintenance and other cost for LED luminous letter in a large extent.

However, users will frequently be confronted with some problems in practical use. The following passage is going to sum up common problems in the use of LED luminous letters and the corresponding solutions for your reference.

Problem 1: Short life-span.
Although the theoretic life-span for LEDs produced by normal manufacturers can reach as long as 80,000 hours, a large number of LED luminous letters have to replace its LED modules frequently even less than one year’s usage. This will bring a lot of troubles and economic losses to customers and advertisement manufacturers.

Solutions:
To buy qualified LED single lamp grains from normal manufacturers (which provide quality parameter for the grain) and make modules yourself. Never to buy cheap LED single lamp grain or finished modules in the electronic products market. If it is necessary to buy modules, you should check how many resistance the module have. The module with only one resistance had better not to be used because resistors will easily get heated and broken after long time durative operating. Once the resistor is burned out, the module will be light-off. Generally, LED lamps are unlikely to be broken, so if the module is broken, just change the resistor with another one that have the same resistance value. Choosing modules with two resistors will leave out this trouble and cut more expenses. In addition, buyers had better get some knowledge of the module makers’ facilities before the purchasing to see whether they have anti-static equipment. Those LED modules produced without anti-static facilities are easily damaged in use.

Problem 2: Quick fade out of the brightness.
The color of the pure and bright LED luminous letters will fade out obviously even after less then one year’s use, making the letters ill-looking.

Solution:
Safe operating current for LED lamp to is around 20 mA. If the current exceed this number, the brightness for the LED will be brighter, but its color attenuation will be quickened obviously. So, before buying the LED module, you should test its output current, making sure the value stay between 20mA and 22mA.(LED module with operating current less than 20mA will be not bright enough; while LED module with operating current exceeding 22mA will attenuate quickly).

Problem 3: Irregular color and obvious color difference.
This problem mainly showed when pure white LEDs are made into large size of luminous letters. The problem is not obvious in the fabricating of single module, but when the whole luminous letter sign is assembled, the color difference will be quite evident. The whole letter surface will be looking like a map with various colors.

Solution:
Color separating process should be undertaken before the white LED lamps are put into the market because white LED will emit light with diverse colors like pure white, blue or yellow. Most small factories don’t have color separating machine as it is expensive. So the white LEDs produced by these factories will be sent to larger factories to be separated. Careless color separating always happens under such circumstance. Some manufacturers even neglect this important process. When buying white LED, buyers should not blindly attracted only by the price, instead should buy qualified products and use identical batch of LED chips or modules with the same color number produced by identical maker.

Problem 4: Sudden light-off or occasional light-off of the whole or part of the letters.
After being used for a period of time, the whole or part of the luminous letters start to flicker, then occasionally light-off and finally completely went out. Most luminous LED modules in the market use plug-in connector, enabling the fixing of LED modules to be convenient for advertisement manufacturers. However, the plug-in connectors exposed in the air are easily eroded and get oxidated after being used for a period of time, leading to the happening of bad contact.

Solutions:
1. Not to use plug-in connector when fabricating modules, instead, using tinned copper lead to connect them and then welding them firmly by active carbon soldering tin.
2. Adopting man-made agate to fabricate complete airtight tridimentional hollow luminous letters to isolate them from the air.

Problem 5: The power-saving trait is not obvious due to the comparative larger power output of the LED luminous letters.

Solution:
Better to adopt LED luminous modules with five lamps in one group. By doing so, the power consumption will be reduced by 40% without changing the number of the lamps.