LED basic knowledge and application analysis

Application 1: Display screens are the main application market for LEDs, and full-color display screens are growing strongly.

my country's LED display market started early, and a number of strong LED display manufacturers have emerged in the market. At present, LED display screens have been widely used in stations, banks, securities, and hospitals. In terms of LED demand, LED display screens rank second only to LED indicator lights, accounting for 23.1% of the overall LED sales. Since the requirements for brightness and life of LEDs used in display screens are higher than those of LED indicator lights, and the average price is higher than that of indicator light LEDs, this has led to the market size of LEDs for display screens reaching 3.24 billion yuan, surpassing indicator lights to top the list and become the main application market for LEDs. With its unique advantages, LED full-color display screens are widely used in stadiums, municipal squares, concerts, stations, airports and other places.

Application 2: The small-size backlight market is slowing down, and medium and large sizes will become the new focus.

LEDs have long been used in the small-size LCD panel backlight market, mainly in mobile phones. The continuous growth of mobile phone production has driven the rapid development of the backlight market. In particular, the emergence of color screen mobile phones in 2003 has promoted the rapid development of the white light LED market. However, as mobile phone production has entered a stable growth stage and the improvement of technology has led to a decrease in the number of LEDs used in mobile phone LCD panel backlights, the growth rate of LED use in mobile phone backlights has slowed down. In 2005, the number of LEDs used in backlights exceeded 1.2 billion, and the growth rate will remain in the single digit in the next few years. The slowdown in the growth rate of quantity and the continuous decline in average prices ultimately led to the lack of growth in the small-size backlight market. At the same time, although the medium and large-size backlight market has become a new favorite of manufacturers, it has not yet formed a scale in 2006. Under the influence of the above two factors, the backlight market will experience a negative growth of 1% in 2006. The scale of the backlight market in 2005 exceeded 1.5 billion yuan.

Application three: The automotive lighting market has great potential, but it is difficult to start the market in the short term.

In 2005, the scale of China's LED automotive application market was RMB 29 million, of which the automotive lighting market was RMB 21 million. From the perspective of the entire LED application market, the automotive application market is still in its infancy and the market scale is very small.

LED as a car light mainly benefits from the characteristics of low power consumption, long life and fast response speed. Statistics show that when a car is traveling at a speed of 100 kilometers per hour, the braking distance of a vehicle equipped with LED brake lights will be reduced by 7 feet compared with a vehicle without LED brake lights. At present, LED has been gradually applied to the third brake light of the car. Although LED is still facing the restrictions of low lumen per unit wattage and related policies, it will take some time to enter the car taillight and headlight market, but with the decline of cost-performance ratio and the improvement of luminous efficiency, LED will gradually realize the transfer from the interior and rear of the car to the front, and finally occupy the entire car light market. With the huge production capacity of automobiles, the LED car light market faces huge development potential.

Application 4: The indoor decorative lighting market is gradually starting up and the traffic light market is entering a period of steady growth.

The indoor decorative lamp market is another emerging market for LED. Through the control of current, LED can achieve hundreds or even thousands of color changes. In the current era of individuality, the diversification of LED colors is conducive to the development of the LED decorative lamp market. LED has begun to be made into small decorative lamps and used in decorative curtain walls in hotels and living rooms. In 2005, the market size of indoor decorative lamps reached 158 million yuan.

After years of replacement work, the work of replacing traditional traffic lights with LED traffic lights in major cities across the country is nearing completion. After many years of rapid growth, the LED traffic light market reached a market size of 1.52 billion yuan in 2005. However, with the completion of the replacement work, the LED traffic light market will no longer maintain rapid growth. It is estimated that the LED traffic light market will only achieve a 5.8% increase in 2006 to 1.61 billion yuan. Application 5: The landscape lighting market is developing rapidly, and the market growth rate reached its peak in 2007.

The landscape lighting market is mainly focused on decorative lighting in public places such as streets and squares, and the driving force mainly comes from the government. Influenced by the 2008 Beijing Olympic Games and the 2010 Shanghai World Expo, the host cities such as Beijing and Shanghai have accelerated the pace of landscape lighting. Due to the low power consumption of LED, it has a strong market competitiveness in the landscape lighting market with huge electricity consumption. At present, LED has been increasingly applied to the landscape lighting market. In 2005, the scale of China's landscape lighting market exceeded 700 million yuan. Driven by the above two major activities, the landscape lighting market will reach a high growth rate of 72% in 2007.

In addition, the main role of the Olympic Games and the World Expo is no longer to drive the growth of the landscape lighting market, but more importantly, to set an example. In order to welcome the Olympic Games and the World Expo, Beijing, Qingdao, Shanghai and other places will build a number of LED landscape lighting projects, which will not only decorate the streets but also serve as a model. Other cities will reduce their concerns about the use of LED landscape lighting after seeing the outstanding performance of LED in landscape lighting, and accelerate the application of LED in landscape lighting. LED will quickly expand from first-tier cities to second-tier and third-tier cities.

Application 6: The general lighting market has a long way to go.

In addition to facing problems such as low luminous efficiency, poor heat dissipation, and high cost, high-power white light LEDs will also face the integration of optics, mechanisms, and electronic control, as well as the formulation of general standards for LED lighting products. It will take a long time to solve the above problems, and CCID Consulting predicts that LEDs will not be able to enter the general lighting market before 2010.

As commercial places such as hotels, business clubs, and high-end commercial office buildings are less sensitive to prices, and these high-end places are more focused on showing off their taste and noble status, they are more interested in emerging products. All these have lowered the entry threshold for LED lighting. CCID Consulting predicts that LED lighting will first enter the commercial market and gradually expand to the civilian market.

Basic knowledge of LED display

Modern society has entered the information age, and information dissemination has become increasingly important. At the same time, people's requirements for visual media are getting higher and higher. They require the media to be quick, realistic (real-time), eye-catching (rich in color, lifelike), and have super-large images and shocking power. In recent years, with the rapid development of microelectronics technology, automation technology, and computer technology, semiconductor manufacturing technology has become increasingly mature, resulting in smaller and smaller LED display point sizes and higher and higher resolutions. The three primary colors of display light (red, green, and blue) can be integrated into one to achieve a full-color effect, which has expanded the application scope of LED displays.

Features of LED Display

LED is the abbreviation of Light Emitting Diode, which is a widely used light-emitting display material in the optoelectronic field. Different materials can produce red, green, yellow, blue and other colors under certain conditions. LED has the following characteristics, making it the preferred material for making large screens:

◆High brightness. Currently, the brightness of a single outdoor lamp is close to 6,000mcd;

◆Low power consumption and high photoelectric conversion efficiency;

◆Long life, LED life is up to 200,000 hours or more;

◆Fast response speed, ns level, no residual ash;

◆Low voltage and low current drive, easy to interface with computer. ·Features of LED display

Compared with other large-screen displays, LED displays have the following main features:

◆The screen size can be large or small, the maximum can be 500m2.

◆Large viewing angle, the viewing angle of indoor screen is greater than ±80 degrees, and the viewing angle of outdoor screen is greater than ±60 degrees.

◆The viewing distance can be adjusted by selecting products with different diameters and different dot pitches. It can meet the requirements from tens of centimeters to hundreds of meters. The current minimum pixel diameter can be 1.9mm.

◆Flexible configuration, from simple digital display to complex full-color video, there are different types of products to meet the requirements, and there are corresponding products for indoor and outdoor use.

◆Easy to interface with computer and supports rich software.

At present, other large-screen displays mainly include the following types, each with its own advantages and disadvantages.

Screen type advantages and disadvantages

The magnetic flip panel has low power consumption and slow response speed, it is impossible to display video, and the failure rate is high

The TV wall is full color with dividing lines, the brightness is low, it is not suitable for displaying text, and cannot be used outdoors

The projection full color picture is delicate but the brightness is low. It cannot be used outdoors and the clarity is poor (the picture is unevenly illuminated).

CRT full color is expensive, consumes a lot of power, and cannot be too large

PDP has a fine full-color screen, high cost, small viewing angle, and cannot be too large

1.3 Classification of LED Display Screens

1.3.1 Classification by application location According to different application locations, LED display screens can be divided into indoor and outdoor types.

Indoor screens are mainly used indoors. In terms of manufacturing process, the light-emitting crystals are first made into dot matrix modules (or digital tubes), and then the modules are spliced ​​into display unit boards of a certain size. According to user requirements, the display unit boards are used as basic units to splice into the size required by the user. According to the size of the pixels, indoor screens are divided into Ф2, Ф3, Ф3.75, Ф4.8, Ф5, Ф8, Ф10, etc.

◆Outdoor screen

Mainly used for outdoor use, the manufacturing process is to first package the light-emitting crystal into a single light-emitting diode, called a single lamp. Single lamps used to make outdoor screens generally use reflective cups with a focusing effect to increase brightness; then multiple LED single lamps are packaged into a single pixel tube or pixel module, and the pixel tube or pixel module forms a dot matrix display unit box. According to user needs and display application sites, a display unit box is used as the basic unit to form the required size. The box should be sealed in design to achieve the purpose of waterproof and fog-proof, so that it can adapt to outdoor environments.

According to the size of pixels, outdoor screens are divided into specifications such as Ф11, Ф14, Ф16, Ф19, Ф21, Ф26, and Ф36.

1.3.2 Classification by base color

According to the color of the LED used, LED display screens can be divided into three types: single primary color, dual primary color, and full color.

◆Single primary color

Each pixel has only one color, most of which are red, because red has a higher luminous efficiency and can achieve higher brightness. Green can also be used, or mixed colors can be used, that is, one part is red, one part is green, and one part is yellow.

◆Dual primary colors

Each pixel has two primary colors, red and green, which can be superimposed to produce yellow. With grayscale control, up to 65,535 colors can be combined by changing the grayscale of red and green.

◆Full color

Also known as the three primary colors, each pixel has three primary colors: red, green, and blue. Under grayscale control, the changes in different grayscales of red, green, and blue can well restore the colors of nature and combine 16,777,216 colors.

1.3.3 Classification by function

According to the functions of the screen, LED display screens can be divided into strip screens, graphic screens, video screens and digital screens.

Four types.

◆Strip screen

This type of display is mainly used to display text. It has its own 16X16 or 24X24 dot matrix font library and can work independently.

It can be used to input Chinese characters through the remote control, and can also be used online with a computer to send information through the computer. It can work offline. Because this type of screen is mostly made into a strip, it is called a strip screen.

◆Graphic screen

This type of display is mainly used to display text and graphics, and generally has no grayscale control. It inputs information by communicating with the computer.

Compared with strip screens, the advantage of graphic screens is that they can display rich fonts and graphics. Compared with video screens, the biggest advantage of graphic screens is that one computer can control multiple screens and can display offline.

◆Video

This type of display screen pixels have a one-to-one mapping relationship with the control computer monitor pixels, and has grayscale control, so its appearance

The video screen is very rich in functions, and can play video signals when equipped with a multimedia card. The video screen has good openness and reflects the display of the computer monitor in real time.

◆Digital screen

Digital screen is the cheapest LED display screen, widely used in bank exchange rate, interest rate display, hotel seafood price list, room price list

In most cases, a strip screen is added to the digital screen to make up for the inability of the digital screen to display text.

◆Hybrid screen

That is, dot matrix digital mixed display, which is most used in securities quotation display.

1.4 Main technical indicators of LED display

◆Smoothness

◆Color uniformity

◆Blind spot rate

Brightness

◆Perspective

◆Viewing distance

Resolution

Resolution

Grayscale

◆Drive mode

◆Communication method and communication distance

◆Scanning frequency

Frame rate

Power consumption

Weight