LED Backlight Light Failure Problem

LED Backlight light failure problem

LED Backlight light is the light in the transmission of the signal weakened, and at this stage the global LED manufacturers have made LED products are different degrees of light failure, high-power LED also exist light failure, which has a direct relationship with the temperature, Mainly by the chip, phosphor and packaging technology decision. At present, Chengdu Haier washing machine on the market after the white LED its light failure may be one of the primary problems into the civil lighting. LED light failure for the following two main factors:

First, the LED Backlight itself Quality:

1, the use of LED crystal body is not good, brightness attenuation faster.

2, the production process defects, LED grain cooling can not be good from the PIN pin derived, resulting in LED grain temperature is too high to make chip attenuation intensified.

Second, the use of conditions:

1, LED constant current drive, some LED voltage driven by the use of LED attenuation.

2, the drive current is greater than the rated drive conditions.

In fact, led to LED Backlight light failure for many reasons, the most critical or hot problem, although many manufacturers in the secondary product is not special note

Heavy heat problems, but these secondary LED products under long-term use, the degree of light will be more than the focus on heat dissipation of LED products to be high. LED 

The thermal resistance of the grain itself, the influence of the silver glue, the heat dissipation effect of the substrate, and the relationship between the colloid and the gold wire are also related to the light failure.

Semiconductor material has a very interesting feature, is the so-called carrier; carrier is divided into two categories: one for the electronics, with a negative charge; another

One for the hole, with positive electricity. LCD luminous principle is the use of two carriers in some conditions can be combined, the release of energy to

The form of the photon is released and glows.

And therefore, according to the different materials, electrons and holes occupied by the energy level is different, that is, the relative energy level of electrons and holes

Poor is to determine the combination of two carriers of the level of energy, can produce a different energy of the photon, which can control the LED

The wavelength of the light emitted, that is, the spectrum or color.

Most of the applications, LED are super-DC way, it has the following characteristics:

Bias characteristic: When the DC has enough positive voltage, the LED current will rise rapidly, and this access to the current

Called "forward current", and the voltage across the LED is called "smooth voltage". If the voltage range is high and low that is the product

Quality anomalies, and usually the shorter the wavelength of the LED its voltage will be higher.

Reverse bias characteristics: As the name suggests is to give LED negative voltage, also known as "leakage voltage", in general, different LED materials will each

The reason why the reverse voltage characteristic is caused by the electrostatic discharge, this feature can also be used to assess the quality of this LED.

LED main material is pn junction, and gate fluid (Thyristor) is the common control of electronic power components, when its thickness is not uniform

Of the time there will be pn level of the situation is generated, then the voltage difference will be very different, this is the "gate fluid effect"

, And if the voltage difference is too large, then the quality of this product is not very good, so this can also be used to measure the quality of LED.

However, generally do not use the brake fluid effect to determine the quality of LED, LED will generally test the VFD to determine. VFD is less than 0.1V

qualified.