how to make a good quality led display for high temperature regions

Led Display For High Temperature

When we intend to install a led display in high temperature environment, the most important thing is make sure the special design. With the special design, it would resist the harsh environment of the high temperature caused by the strong sunlight, or geographical factors such as equator, tropics, and desert. 

There are three factors we'd need to pay attention to:material(components), design & production.

Material

Now we would like to tell you some factors which influence the displays’ quality. Hope it is useful for you. 

1. Led module:

No matter indoor or outdoor led display, they all composed by led modules. Led modules are include( led lamps, driving IC, pcb board and module frame). its size can not be changed easily.

2. Display Panel

Display Panel is the main body of the screen. It is made up of light-emitting materials and driving circuit. The display panel of indoor and outdoor screen are unit cabinet.

3. Display Control system

Display controller are mainly include sending card, receiving cards and computer. The sending card should be installed inside the computer, the receiving cards should be installed inside the cabinets. usually one cabinet needs one receiving card.

4. Switching Power Supply

It is used to transform the 220V/110V alternating current into all kinds of direct current to support various circuits.

5. Transmitting Cables

The display data and all kinds of controlling signals generated by the host controller are transmitted through twisted-pair cables to the screen.

6. Scanning Control Board

The function of it is to cushion the data, generate all kinds of scanning signals and duty cycle grey scale control signals.

7. Special Video card and Multi-function Card

The special video card of full color LED screen not only bear the basic functions of computer video card, but can also output RGB digital signals and row, field and blanking signals to the host controller. Besides functions the same as the special video card, multi-function card can also change the input simulated video signals into RGB digital signals (that is the collection of video communication).

8. Other information sources and devices

Including computer, TV set, blue-ray disc, DVD, VCD, video camera and recorder and so on.

Choose the best quality material:LED chip,driving IC,Power supply,cabinet sheet,PCB board

Introduction of LED module

1. What is LED module?
LED module is a basic unit of led display, which has complete drive circuit and certain appearance.
Outdoor LED module

Indoor LED module


2. LED module classification.
a.Classifying from the application environment, there are two types led modules. One is indoor LED module and another one is outdoor LED module. The latter module must be water-proof.
b.LED module can also be classified from its color, such as single color led module, tricolor LED module and full color led module.
c.According to the type of LED, the LED module can be classified into DIP LED module and SMD LED module.
3. The composition of LED module.
The LED module is consisted of the following parts & components:
a.LED.
b.IC. Generally the driving IC model we used include,

  ⅰ.Macroblock MBI5020, Macroblock MBI5024;
  ⅱ.Macroblock high refresh rate MBI5042, MBI5050,MBI5151,MBI5252,etc;
  ⅲ.Macroblock energy saving MBI5035;
  ⅳ.Macroblock error detection MBI5036;
  ⅴ.Toshiba TB62726;
  ⅵ.Philip 74HCXXX;
  ⅶ.ANPEC4953.
c.PCB. There are so many kinds of PCB in the market, such as single layer board, double layers board and four layers board etc. And the PCB we adopt to our led display modules: FR-4; 1.6mm thickness; Copper foil thickness 35(1oz), SMOBC&HAL, black or green surface painting.
d.Signal connector. There are three types as following,
 ⅰ. Contact pin. It has price advantage, low cost.

 ⅱ. Fence shape. Its price is a little higher than contact pin.

 ⅲ. Ox horn shape. It fixed firmly and its cost price is high.

We use only the best type connector to ensure the stability of our led displays. And if there's no special requirement, the power connector we use is VH4 to give the great convenience of the maintenance to the led displays.
e.Module kit.
 ⅰ. Bottom case. It is just like a carrier of the LED module, the whole LED PCB will be put in it. It seems like a container when the LED module is used to outdoor environment, since the waterproof silicon glue will be poured into it and seal around the LED to realize waterproof.
It is LED's basic structure and whether there is cabinet or not the LED module will be installed on the cabinet or frame through it. The bottom case also can protect the LED from damage when under the working state.
 ⅱ. Mask. There are three kinds of mask in the market.
  1）Conventional hard plastic cement mask.
  2）Soft mask. It is usually for sport perimeter led display usage. Considering the athletes' safety and the intactness of the LED display, at the first layer of the LED display the PC mask will be used and then the soft mask will be attached on the surface.
  3) Silica gel mask. It is mainly used to the smaller pixel pitch LED display and can be pasted on the LED PCB with 3M glue.
f. Resistor and capacitor.
ⅰ. Resistor model: 0603, 0805, 1206 etc.
ⅱ.Capacitor types: electrolytic capacitor, SMD ceramic capacitor.
We use high precision resistor to ensure the color of LED display to be disposable, and to make our products more reliable.

Outdoor LED modules composition parts are generally the same with the indoor LED module, but there will be waterproof silicon added into the bottom case, making the LED side completely sealed to be waterproof; as well the back side of the PCB will be coated with conformal coating. Besides, the rubber ring that will be pressed on the bottom case and when the LED modules installed onto the cabinet there will no entrance for water, this is one of the reasons that the outdoor LED display can water- proof.

LED module adapting best quality LED chip,driving IC,PCB board

LED Module Test

LED module test is necessary after you've fixed the LED or the IC of the broken ones. You need to make sure the LED module working well. To test the led module, usually we will use the receiving card. It is the most convenient way to press the test button on the receiving card. For more details, please visit our blogger pages.

Waterproof Outdoor LED Display Cabinet

Outdoor LED display cabinet is designed with waterproof feature, which is a must for the outdoor application. It is found from the specification sheet provided by most the China LED display suppliers that the ingress protection is IP65. In fact, for the front side of the LED display screen, it's not difficult to reach the IP65 ingress protection, because the LED module is sealed with waterproof glue between the LEDs. And between each LED module and LED cabinet, there is waterproof rubber O-ring. And Dakco LED display can reach IP67 in the front side of the LED display.
But as for the back side of the LED cabinet. As long as there are the back doors, the ingress protection can't reach IP65, because the first number "6" stands for the "Dust Tight, which means no ingress of dust and complete protection again contact".
So in most cases, when install an LED display which has the back doors, it's better to build a protection cover on the back of the LED display, to ensure the safety of the LED display screens running in extremely weathers.
But that doesn't mean that this kind LED display screen can't be built without the protection frame, under the total outdoor environment. Just when you have this requirement, we will design the cabinet specially, for example with a protection eave integrated with the LED cabinet, or even with 2 levels of doors. That's also the reason why when we make a LED display solution, we will ask a serial of questions, to clear understand the situation, and bring out the most suitable LED display solution.

LED Cabinet adapting best quality cabinet,fans,wire,

Design&Production

As a matter of fact, the signal led is very easy to broken, so its making process must be very careful. The humidity control and anti-electricity protection are highly request. Now with the development of the technology, many modern machines are used in this process, include the led inserting machine, wave-peak soldering machine, hot air re-flow soldering machine and others. However, there are still some manufactures don’t use these machines but hand-working. This factor will influence the led display quality very much. We pay more attention to this detail. Instead of hand-working, We put the machines into all the making process. so our quality is reliable. If available, You’d better to visit the factory first before you make any decision.

                                                                   LED Module Design

please refer to our other blogger pages for details.

LED Cabinet Design

LED cabinet is the basic modular unit that clients receive to assemble the led screen panel. But the importance of led cabinet design is easily ignored.

In some clients or even the sales person's opinion, led cabinet is just a unit to housing the small led modules, power supplies, and other components. Indeed, this is the very basic function of the led display cabinet, but the led display manufacturers should consider much further than this. A good led cabinet and a bad led cabinet have almost the same outward appearance, but in the practical operation, the influence to the led screen performance is totally different.
Then, what need to be considered, when design the led cabinet?
                                                                
Firstly, it should protect the led modules, power supplies, and all the internal components and devices well.
Secondly, it should ensure the safety of the operation, and it must reach the high level ingress protection, without the entry of dust and water.
Thirdly, which is the most important and easily ignored, is the design of heat loop. We say this is most important because most the manufacturers could accomplish the requirements of the above 2 items, but this item requires higher design level.
Following with the long operation time and the temperature of environment, the heat emitting would rise. If the heat couldn't be dissipated efficiently, the led screen quality would be down, and the lifetime would be short.

This sounds very easy to understand but to accomplish a good design, it's not easy at all. The led display manufacturers must pay great attention to it.
A bad designed led cabinet will not influent the led display quality immediately. For a newly installed led screen, it may seem all right. But after a period of running, all the problems will emerge. And this, is very similar with what we call "hidden problem" of led display screens.
At last, when have an RFQ, the clients find "the only difference is the price". But it's better to learn that it is very easy to show words and pictures in email, a good description doesn't mean a good quality. Sometimes, with the reasonable margin, the higher price is of the better quality product.

LED display aging test

In the process of LED display production, aging test is an indispensable part for LED displays, but hardly get a mention by purchaser. Here I’m going to give a simple introduction about it.
Aging test of LED display refers to in an imitating test environment, to show whether the abnormal phenomenon of the LED display will occur when it work in a long operating time, it’s an important step to ensure the reliability of the LED display screen and essential for quality inspection and quality guarantee. After aging, the efficiency and the stability of the LED display can enhance in further use.
The aging test contains two parts: LED module aging and the whole LED display screen aging.
1. LED module aging
LED modules cannot be used directly after they are produced; aging is the last necessary step. The modules are aging in a sealed room which the constant temperature is 45℃, this will last 24 hours during aging.

2. LED display aging
The whole LED display aging will last 48 hours, during this time the electricity supply shouldn’t cut off. Aging of the entire screen for a total of 48 hours, including 24 hours of white screen aging, which means the LED display screens are showing white color all the time during the aging; and the remaining 24 hours of video aging, during this time the LED displays are playing non-stop video, in order to ensure the display screens have no problems before shipment.

LED display Inspection

In the process of LED display production, display Inspection is the last step of the whole production processing. Inspection includes waterproof inspection, vibration inspection,vandal inspection.

                                          Several Factors to Guarantee the Quality of LED Large Screen

With the improvement of people's living standard and the progress of science and technology, led  large screen in the community has been widely used, led large screen quality can be guaranteed of following several factors.

First, the complicated temperature has great influence on the led big screen. LED display is very critical to the ambient temperature , in theory, at room temperature about 25 ℃ is the best of their work status. But in fact, in the application of outdoor led display screen, the temperature change is complex. Maximum temperature in summer may be above 60 ℃, the lowest winter temperature may be -20 ℃ even lower, working on this fluctuating temperatures has a great influence on the quality of  large led display. In different temperate condition, the brightness decay and decline of red green and blue light is different also. When in 25℃,the white balance is normal, but in 60℃,the brightness of three kinds of led light will reduce, and the  its attenuation value is inconsistent. So, it will reduce the brightness of led screen and the color off phenomenon, the quality of the whole screen will drop. But in the high temperate, the IC in LED large screen will lead to job insecurity because the temperature is too high, or have a channel current differences owing to the different temperature caused screen is fuzzy . So the constant temperature is the most important to the quality led.

We need the led display could resist the highest temperature of 60 Celsius.But what need to be noticed is that the LED display is actually composed by a big quantity of components which are all belong to electronics. For any electronic device, a suitable working environment would last the lifetime, which is no doubt.

So as a good suggestion, if the installation environment allowed, it's better to create a suitable working environment for the led display. And in case of the high temperature location, it would be perfect if could install the air conditioner inside the maintenance channel, please refer to the picture as below:

To save the power energy, and to make the air conditioner control easy, usually the air conditioner would be designed as temperature-sensed, i.e. the air conditioner will run automatically only when the temperature reached a defined value. And it is not difficult to realize this. If there's any problem, please just contact us and ask for the solution.
And here is some suggestion on deciding the suitable air conditioner: one PH will afford 9m3 space inside the maintenance channel.

At last, we need to note: the air conditioner would be helpful to last the lifetime of the whole led screen, but it doesn't belong to the rigidity requirement of the led display installation. Especially for the small size led signs, there's usually no maintenance channel left behind, in addition that the air conditioner will increase much cost comparing the total investment of the project. In this case, usually the air conditioner part is cancelled. With special design of heat dissipation, the led screen sign will not have the problem belong to the malfunction range, just the lifetime should not be as long as the led displays running in a suitable temperature range.

The composition of a complete LED display cabinet

Just like man is composed by various kinds of organs, the LED display screen is also consisted of many parts. As the modular design, the basic modular unit of the led display screen is LED cabinet. In another word, the LED cabinet itself could be treated as a small size led display. So as long as you get familiar with LED cabinet, you get familiar with the led display. Generally speaking, a regular led display cabinet is consisted of six major parts:

1. LED Modules
The LED modules type generally includes DIP and SMD LED modules, the pixel pitch usually ranges from 3mm to 25mm. The smaller the pitch, the shorter the viewing distance, and the higher resolution per SQ.M. The DIP type LED modules are usually used to the application of outdoor environment, and the SMD type modules are mostly used to the indoor application however it's not absolute.

2. LED Cabinet
Firstly the "led cabinet" we mention here is just the "frame" to "hold" all the parts. It is one part of the "finished LED cabinet".
Usually we have two kinds material of LED cabinets, they are steel plate and aluminum plate. We can use the two kinds of material to manufacture different types of cabinet, such as simplified cabinet, standardized cabinet, curved cabinet, circular cabinet, double door cabinet, football perimeter screen cabinet, lifting cabinet, front open cabinet, double front open cabinet etc. These cabinet can be customized according to your actual project condition and you requests.

3. Power Supply Units
The power supply we mainly use is MEANWELL branded which is acknowledged to be the best for led displays application. And the input voltage is generally 220V±10% / 110V±10%. It includes different specs to suit different working temperature as well.

4. Cooling Fan
We mainly have three kinds of fans, oil-retaining bearing fan, rolling ball fan and mute fan. The oil-retaining bearing fan's life time is 2-3 years, its working noise is small. The rolling ball fan is durable, its life time is much longer than oil-retaining bearing fan while its working noise is bigger. The mute fan is with the advantage of less noise, longer life time however the price is higher.

5. Control System (Sending card and receiving card)
We mainly use four brands cards, LINSN, NOVA, DBSTAR and XIXUN. We will equip your LED display screen with proper cards according to your actual project condition and your requests.

6. Wires and Cables
The power wire and ribbon cables are connected between the LED modules, power supply units, cooling fans and control cards.

How to know the scan mode of led display?

As a frequently mentioned professional terms, "scan mode", also called as "driving method", sometimes makes the beginners or even the experienced clients feel confused. In fact it's not so hard to understand. For example of 1/4 driving led display, you could simply imagine that at one moment, only 1/4 of the LEDs are driven on by the driving IC. Certainly it's hard to sense it by human eyes, but the professional cameras, when we set which at very high shutter speed, it is possible to capture it. The exist of scan mode 1/4, 1/8, 1/16 etc is reasonable, because sometimes we don't need very high brightness, very high refresh frequency, and sometimes we need to reduce the power consumption as well as the cost...but in this article, we're not introducing the details of this concept, or analyzing its reason why. Instead, we're introducing "how to know the scan mode" of led display when you see one LED module in hand.

And yes it's very easy to work out this.
Taking an example of the P3 LED module.

You will calculate out the scan mode of this LED module in below 3 steps:
1. The total pins amount of this LED module's driving IC.From this picture can find that there are 8 small groups of LED driving IC, and each group contains 3 LED driving IC, so we would know that there are totally 8x3=24 LED driving IC;
Each LED driving IC has 16 pins;
So we would know there are totally 24x16=384 pins of LED driving IC on this LED module.
And let's record this number 384.

2. The total LED chips amount of this LED module.The resolution of this LED module is 64x32=2048 pixels, and each LED contains 3 color chips(R,G,B), so there will be totally 2048x3=6144 LED chips.
Let's record this number 6144 too.

3. The formula - "scan mode = total pins amount of LED driving IC / total LED chips amount"

Finally we get the result 384 / 6144 = 1/16

The composition of outdoor LED display module

LED module is the most important part of the LED display screen. It's just like the face of man that through it we can see "facial expression". Outdoor led display module usually ranges from pixel pitch 10mm to 25mm. Nowadays P10mm and P16mm are the mainstream spec in this field. And for most led display manufacturers, the spec P10mm is still the smallest pixel pitch they can do. But with innovative production technology, we can now supply P6mm and P8mm outdoor led display modules. Generally the major parts of outdoor led display module are similar. It contains below 5 major parts:

1. LED. LED chip brand varies a lot such as NICHIA, CREE, SILAN etc; in addition with different encapsulation companies, the finished LED in market could have hundreds of different quality levels. It's hard to tell the quality difference with only seeing those LEDs, even the newly finished led display screen. To verify the quality performance, there's no better way than seeing its performance after long time running. This is a hard problem when the customers source the led displays because probably their potential supplier's led displays seem to have little difference. But just like the saying "you get always what you paid for", it is impossible to get the best quality led display in the lowest price. Sometimes this common sense is thrown away when consider the dollars could be saved. In fact, this is even not a way to save the cost because at least a seller should be confident enough to offer 3 years warranty. So when there's continuous problem happen, the after sale service you have to do will consume up what you have saved into the pocket - and maybe it would be not enough. The worse point is the lose of reputation, remember the led display screen is installed where all the people could see. When a seller's installation are all poor quality things, nobody would like to buy the same. As a conscientious led display manufacturer in China, we don't recommend our customers use those poor quality led displays. And we have enough good references all over the world, which are more convincing than thousands words to say in paper.
And certainly we consider the affordable cost too. So we consider is in fact the "cost performance". At present we mainly use EPISTAR LED, which is acknowledges to be the very good quality, and better than China mainland brands. If you're interested to learn more details, please contact http://china-led-display-screen.blogspot.com

2. Driving IC. The driving IC plays the role just like the "nervous system" to a human body. It controls directly each LED's on & off, the brightness, the frequency etc through the precise current feed. So the current precision and durability of it is very important. Just like the LED, there're more than enough brands driving IC in market. We use mainly the reputable Macroblock brand. And the major spec for outdoor led display modules is MBI5020.

3. PCB. There's no necessary to explain much about the importance of the PCB (printing circuit board) - it's the body to carry all the key components, and all the circuits are on it. The PCB we are using is KB FR-4 PCB, and its thickness is 1.6mm.

4. Module Kit. The module kit contains 10-15% glass fiber which made it more durable.

5. Waterproof silicon glue.

This is just a simple explain, if you're interested to learn more, please contact http://china-led-display-screen.blogspot.com

Waterproof measures of outdoor LED display - module part

As for outdoor LED display, there is no doubt that we need to do some waterproof measures for it. The waterproof measures must be done at both the LED module part, and the LED cabinet part.

In this article, I'm going to introduce how we acheive that at led module part:

a. For the LED modules, all LED pins which contact the PCB, are sealing with silicon glue, so that the rain water can’t insinuate into the module inside, the silicon glue will protect the circuit from short out or damage. Look at the following pictures and get a more intuitive feeling. Above the silicon glue, there are still to install a module mask, this is not only dual waterproof, but also protect the LEDs from man-made damage and to enhance the contrast of led display.

 
b. When the LED modules are install on the cabinet, between the modules and cabinet there must be tightly coupling without any gap. The waterproof rubber ring is the best solution for this, as the rubber rings have good strong bounce and durable. With pressing tight between the led module and cabinet, there is no worry about the water leaking in.

If you'd like to learn more details, please visit our page http://china-led-display-screen.blogspot.com 

Some factors should be considered when buy a LED display

Firstly, you should know where would you install the led display screen, for indoor or outdoor, and what's the installation environment? This is the key point because the brightness for the indoor and the outdoor LED display are different. For outdoor, the brightness should be higher than indoor’s. As indoor LED display screens are just bright enough to be seen indoors, but have not brightness high enough to be seen in direct sunlight. Outdoor led display screens can be seen and used in full-on, mid-day sunlight, and are weatherproof to withstand the harsh environmental conditions. Once you tell us the installation environment, we will recommend you the most suitable solution.

Secondly, another important factor that you must consider is the displayed content on the led screen, Text or Graphics or Video? There are three series for you choose: monochrome color led screen, dual color led screen and full color led screen. Generally speaking, if you are looking for a simple, programmable, only text led sign, you can choose the monochrome led screen, there are plenty of scrolling message led signs to be chosen from. If you want full motion graphic animations in addition to scrolling text, you can choose the double color led screen or full color led screen, and if you want to show the video, the full color screen would be the best choice.

The last but not the least is the control system. There are two systems for your choice: synchronous control system and asynchronous control system. For synchronous control system, it means the led display screen must be synchronized with the signal sources like computer etc, there must have the network cable to connect each other, so the distance between the led screen and controller should not be too far. The distance should be within 100 meters usually. For longer distance, it would require the fiber optical as the communication media.
But the asynchronous control system could combine the wifi router and the 3G router etc wireless equipment easily. So the asynchronous control system is suitable to be used in a wide range and long distance.

If you need an offer or want to learn more about led display, please email mydisplay2008@gmail.com

LED Display Module - General Introduction

Almost all the LED display screens are customized. Customers have different requirements: different installation environment, different function requirement, even different budget level. All of these factors must be considered when choosing a led display screen.

Before choosing a LED display screen, customers need to learn more about this product. The more you learn, the better decision you make. Certainly you can get the suggestion from the sales of led display manufacturers, still you'd better learn more yourself, because no salesman would say bad words to his offer. When every salesman are trying to convince you that they can provide the best and most suitable led display screens and solutions, you need to judge on your own which one is trust-worthy.

Now we're starting some technical article series to introduce all the parts of led display - LED modules , LED cabinet , switch power supply units and control system etc. We believe it would be good reference when you're going to purchase the led display screens. In this technical article serie, we are introducing the most important part of led display screen - the led modules.

LED module consists mainly of LED lamps, mask, bottom case , PCBA, drive IC and waterproof rubber.

1. LED lamps. LED lamps can be generally divided to be two categories : SMD LED and DIP LED.
Generally the LED size we choose depends on the pixel pitch of led display screen. The smaller pixel pitch we want, the smaller size LEDs we use. The table below shows the relationship between the different pixel pitch and several common sizes of LEDs.

Some experienced customers sometimes point out the brand of LEDs they want, EPISTAR, CREE and so on. Most of times they pay more attention to the brand of LED wafer but ignore the package process, i.e. encapsulation process.
When the quality of wafers determine the feature of color, brightness and luminous decay, the package determines the reliability, durability and life span.

There will be much information need to be introduced, so we will leave the details in next technical article which will be updated shortly and continuously.