STONE Intelligent TFT LCD Module

The core of LED backlight display technology is to replace the traditional fluorescent lamp with LED light-emitting diode as the backlight of LCD display. LED backlight display technology is one of the "future" core technologies of LCD products.

LED backlight display and CCFL backlight display contrast

In the electronics industry, backlight is a form of lighting, often used in LCD displays. The difference between backlight and front light is that the backlight is shining from the side or behind, while the front light is shining from the front as the name implies.

LED backlight display refers to the use of LED (light-emitting diode) as the backlight of LCD screen. LED backlight display technology LCD, which can expand the color gamut of LCD to 105% of NTSC standard, can basically reproduce most of the natural scenes observed by people.

The traditional LCD display usually USES the cold cathode fluorescent lamp as the light source.

Compared with the traditional CCFL (cold cathode tube) backlight display, LED has the characteristics of low power consumption, low calorific value, high brightness and long service life. It is expected to completely replace the traditional backlight system in recent years.

Why is LED backlight display technology widely concerned?

The most important reason is that LED backlight technology is particularly bright color led backlight tv. In the field of video, people generally use NTSC as the standard to measure the color reduction characteristics of video devices. This index is to point to inside whole colour space, display equipment can be shown on all sorts of colour what kind of saturation, can show conspicuous namely what to reach.

What are the advantages of LED backlight display technology over traditional CCFL backlight display？

11 advantages of LED backlight display technology

1. Long service life of led backlight display. In general, led bulbs have a very long life compared with other ordinary lamps, which can last more than 10 years;

2, LED is a kind of planar light source, the most basic luminous unit is 3 ~ 5mm side length square package, very easy to combine together into a given area of surface light, with good brightness uniformity, planar structure makes the LED has a stable internal structure, seismic performance is excellent. If used as the backlight of LCD TV, the auxiliary optical components needed can be made very simple and the screen brightness uniformity is better;

3. The flickering frequency of the traditional CCFL lamp is low, which may generate flickering image in the performance of dynamic scene. The LED backlight can flexibly adjust the luminous frequency, and the frequency is much higher than that of CCFL;

4, LED brightness adjustment range is large, LED backlight display can adapt to a variety of states of environment, unlike the minimum brightness of CCFL there is a threshold, general energy-saving lamps if in the state of frequent opening and closing is very easy to break, and LED bulbs can adapt to this high state of work environment;

5, the production of led backlight display, using the world's top lighting production technology, its light source for the surface light source, this light source can increase the luminous surface, very close to people's eyes;

6. There is no mercury, lead or other harmful substances in the led backlight, which is environmentally friendly;

7. The temperature of LED backlight is generally stipulated to be -20°C~80°C;

8. LED USES a low-voltage power supply of 5-24v, which does not need high voltage. It is very safe, and the design of power supply module is quite simple;

9. LED backlight display has better color gamut and its color expression is better than CCFL backlight display; Color: red/green/blue/yellow/white/orange/purple/pink;

10. LED can use red, green and blue to emit light independently, which is easy to accurately control and display color characteristics;

11. The white balance of LED backlight display can ensure the overall contrast and brightness.

7 causes of LCD Display screen flicker

The reason of LCD Display flashing screen: shielding coil; Signal interference; Hardware; Refresh frequency setting; Monitor time is too long; Too high frequency; Similar to the frequency of the light source.

CCFL backlit display versus LED backlit display

LCD display, divided into CCFL backlight and LED backlight two. When the display using CCFL backlight (that is, usually said LCD display), backlight power off, the lamp will continue to emit light about a few milliseconds; When the display is backlit with an LED (commonly referred to as an LED display), the characteristics of the LED light allow it to control the speed of switching on and off the power supply more quickly, so there will be no continuous lighting when the power is off.Therefore, the LED backlight flashing screen will be more obvious than CCFL backlight.

The reason of LCD screen flashing

1. the LCD Display cable shielding coil

Whether the cable connecting the LCD has no shielding coil, if there is no anti-interference black bump, will also interfere with the screen.

2. Whether there is signal interference near the LCD Display (strong electric field or strong magnetic field interference)

LCD is easily disturbed by strong electric field or magnetic field, and sometimes the screen jitter is caused by the magnetic field or electric field near the LCD.To liquid crystal display ruled out clean everything around interference, the computer can be moved to an empty table, surrounded by then boot test, if the screen dithering phenomenon disappears, it means that your computer where you found it has a strong electric field or magnetic field interference, please send suspicious (e.g., speakers of the subwoofer, power transformers, magnetizing cup, etc.) from a computer nearby.

3. LCD Display hardware problems

Turn off the LCD and turn it back on a few times to degaussing. (today's monitors have automatic degaussing when turned on.)LCD screen flashing reason: screen refresh rate problem & display and video card hardware problems display.

4. Refresh frequency setting of LCD Display

In fact, the main reason for the LCD screen dither is the LCD refresh frequency set lower than 75Hz caused by, at this time the screen often appear dither, flicker phenomenon, we only need to put the refresh rate to 75Hz above, then the phenomenon of the screen dither will not appear.

5. the use of LCD display time is too long

Sometimes because the use of liquid crystal display time is too long, there will be jitter phenomenon. In order to test whether the electronic components inside the display are old or not, the faulty display can be connected to someone else's computer for testing. If the fault still disappears, the display is broken and needs to be repaired.

6. The frequency of the LCD display screen itself is too high, resulting in flashing screen

The frequency of LCD display screen itself is too high, which leads to screen flashing. Generally, there are few problems in real life that cause screen flashing due to high frequency. People's naked eyes have no flicker feeling for the picture over 60hz, while the design standard of general LCD display screen is basically maintained on this data, so the frequency will not be too high under normal circumstances, but at the same time, the screen itself can not be ruled out fault. After the relevant instrument measurement is indeed the fault of the screen itself, in addition to the replacement of a new monochrome LCD screen is the design of equipment related software.

7. LCD display and light source frequency similar to cause flashing screen

LCD display and light source frequency close to the situation of the splash screen is very common, because the frequency of the different light source is different, in certain cases, the frequency of the LCD display screen and artificial light similar flicker is also more common, the best way at this time is a kind of artificial light or LCD display equipment, avoid the splash screen.

LCD display, although the price is not high, but there are various problems. It will have various effects on our work and life. In ordinary life, when using LCD, as long as pay attention to the following points, will extend the life of LCD. Click to view the notes for use of LCD: https://www.stoneitech.com/about/news/sharing/notes-for-outdoor-lcd-application.html

At ordinary times, some customers ask us how to carry out routine maintenance of TFT LCD module. As a professional LCD supplier in China, we provide professional pre-sales and after-sales consulting services. The following article will show you how to use and maintain an LCD monitor. Click to view: https://www.stoneitech.com/about/news/sharing/lcd-display-be-maintained.html

Thursday, October 10, 2019

Backlighting has fully penetrated all sizes of LCD screens

Because LED has a series of advantages such as energy saving, long life, fast response, good color reducibility, mercury free and environmental protection requirements, it has replaced the traditional CCFL backlight and become the mainstream backlight for tft lcd display (LCD). Now in the application of large LCD display screen, LED backlight has gradually become the mainstream.

Small size LCD LED backlight LCD screen, mainly used in mobile phones and digital cameras, and some industrial instruments use monochrome LCD module, the screen size of 3 ~ 7cm, with LED as backlight, as long as the use of 3 ~ 6 white LED, series or parallel can be.If a white LED flash is used in the same device, a larger driving current is required.Sometimes the backlight brightness is not fixed, but allows the user to adjust the brightness in white lines, which requires the driver to adjust the brightness (that is, change the driving current).Because this kind of demand is increasing, many analog integrated circuit, power management integrated circuit manufacturers to adapt to this demand, have developed and produced a variety of integrated circuit drive LED.

This kind of circuit generally has the control function of LED backlight and LED flash, as well as the function of on and off control and multi-stage brightness control. It has strong functions but few external components.Many of the chips that drive leds that we will cover in the following sections fall into this category, and there are many suppliers and product models to choose from.Display devices with larger display sizes than mobile phones and digital cameras, such as personal digital assistant (PDA), portable media player (PMP), electronic dictionary, handheld game console, etc., have display sizes ranging from 9 to 10cm, and Max can also reach 18cm.

Due to the current LED illumination is difficult to achieve uniformity in the large screen scope, so the size is no longer suitable to use multiple LED direct configuration to do the backlight, but to use a backlight module, in the backlight module, the use of refraction, light guide plate and other measures to make white LED illumination uniform, meet user requirements.PDA and PMP manufacturers buy these modules directly from backlight armour module vendors instead of using several leds to make up the backlight.However, in some designs, some people still use more leds (such as 8 to 10) to make backlight for larger LCD screens.

LED backlight of medium size LCD screen is mainly used in portable DVD, notebook computer, car navigator and other equipment, such as 7-12 inches, the LED backlight adopted by them is developed on the basis of the drive scheme of LED backlight of small size LCD screen.Article USES the aluminum LED to replace the CCFL light source, the drive power supply shall be as far as possible with existing CCFL backlight driving power on the interface compatible with each other, with simple dc drives (with batteries, many for the 12 v power supply) to replace the complex ac drives, although its comprehensive cost is a bit expensive, but it is similar to the traditional CCFL backlight module.At this time, if multiple LED arrays are still used, due to the increase in the number of LED, the serial and parallel LED groups are generally considered as a whole, and the driving power is used to control its current and adjust its brightness.

LED backlight of large LCD screen in the LED backlight of large LCD screen, it is possible to light up hundreds or more leds at the same time to provide sufficient brightness, which requires higher voltage, more current, more flexible control mode and more strict heat dissipation of the driving power.At the same time, also put forward higher requirements for the consistency of LED characteristics, the driver and LED current matching and flow sharing.The LED used should be strictly screened and classified according to the luminous wavelength and brightness of the LED.When testing LED optical properties and classifying parameters, most of them are based on consistent rated current value, and then give the allowable variation range of forward pressure drop.It is expected that large LED screen backlight will soon replace CCFL as a mainstream product.