LED display card is cord part of LED display part. LED display to show the variety of text, symbols and graphics 。 The content of display from a computer to edit, adoption of display control card to show the content via RS232/485 of computer. This LED display is mainly for the variety of text, symbols and graphics .first ,the information of display by computer to edit. Output the information into LED Screen memory via RS232/485 serial port。Then to display in circles. The mode of Display is rich and colorful, and display work offline. It’s flexible control, convenient operation, low cost, is widely used in various sectors of society.

Synchronous LED screen control card:
Synchronous LED control card, it’s mainly used to display real-time video, graphics, notification. is widely used in indoor or outdoor full-color large screen display.the work way is same Synchronous control system led LED display control card and computer monitor, it takes at least 60 frame / sec update rate corresponding to update the map image on a computer monitor, typically have the ability to display multiple shades of gray, it’s can be achieved multimedia advertising effect. Its main features are: real-time, enrich expressive, the operation is more complex, high price. A synchronous led display control card system in general by sending cards, reception cards, and DVI graphics cards. Synchronization led display control card.Asynchronous LED display control card is also called offline LED control card or offline card. It’s mainly used to display a variety of text, symbols and graphics or animation. Screen display information by computer editing, frame memory through the RS232/485 serial port implantation of LED display screen in advance, and then screen display, play in circles, display way is rich and colorful, diverse. Its main features are: simple operation, low price, wide application range. Simple asynchronous LED controller card can only display digital clock, text, special character. Graphic asynchronous LED control card function that has simple control system . the biggest feature is according the zone to control display screen. Support analog clock display, countdown, pictures, tables and animation display. With a timer switch, temperature control, humidity control and other functions.

Synchronous LED display control card:
The card of send To plan or arrange the show content according to a specified form and play order at VGA display. Other side the show contentAt VGA display will be send to control board through card of collect.Collect card is interface card using to connect of display card and LED screen.Receiving card can be receive video signal (control signal and data signal) from the sending card. the data of video signal through the data separation, the data field is stored in the external cache, then according to the zone to read, transmitted to the display screen.

Asynchronous LED controller card:
The computer Edited display data will be stored into LED display control card, does not affect the LED display after the shutdown of the computer. this system is asynchronous LED controller card.

LED controller used control of led switch by ic chip.

1, low voltage led products, large power controller
In general the design voltage of low voltage products as 12V-36V, the quantity for each loop of 3-6 in series . LED current limiting with the current limiting resistors, each loop current below 20mA . A LED products has a lot LED loop to composing. Advantage is low voltage, construction is simply , easy to design ; the shortcoming is: the current large when product size big, low voltage switching power supply need install. due to the limit of products disadvantage. The Low voltage con’t long-distance transmission. are confined to a small volume products, such as: text of signboard , small text pattern. According to the features, specification of product design: 12V choice of 75A/30V MOS to control, output current as 8A/channel; 24-32V choice of 60A/50V MOS to control, output current as 5A/chanle; Users can select the channel quantity of led controller, according to the above specifications, Note that the LED must be a common positive(+) pole connecting method, controller is common negative(-)pole, controller is not include low voltage source.

2, Low voltage LED in series controller
multi- control channel is mainly feature for The low voltage led in series controller. Used the transmission of in series single to realized a purpose of control . in general, 512 unit just only need to control of four control lines, the in series LED controller need to configuration of register at light source board of LED .

3, High voltage LED controller
The high voltage led controller is alternating voltage(AC). Echo circuit loop has 36-48 in series of LED, and echo current of circuit loop is 20mA below. There are has two kinds of current limiting mode, one is the resistor limiting current. The resistance power consumption is large in this mode, suggestion that echo of four resistors are connected in series with a 1/4W metal mold resistor. Uniform distribution of heat, this mode is most stable and reliable in currently. Other mode is the capacitance connected in resistance to limiting current. A lot of voltage drop across the capacitor at the connecting method. Resistance power is small. But it just only runs in stable of supply power. The capacitor energy is storage when the supply power is unsteadiness.Thereby LED easily damaged. Any used the controller to control the led with resistance limiting current is necessarily. Echo loop of led has one meter, and power 5W,three-color per meter 15W.
finally: attention should be paid to load matching! The light distribution of neon and LED’s are not the same, the same circuit can not be mixed with different types of load.

1，Design of Music LED Lighting Controllers
1.1,Theory of music lights rhythm display system
1.1.1,require analytics
When Design of a system, first know that the market demand, to ensure that do such a system is necessary ,second to determine the status of current market and the most recent scientific research to ensure the system of their own design is practical and advanced.

1.1.2 the analytics of system function
First we should be know the purpose and useful for any system. the music light display system is external lights along with music beat to display. For the application of systems is divided into three parts: input parts, mcu part and output part.Input parts refers to the music from the external input to the MCU process. MCU processing refers to deal with the input data with MCU, and for the output display part provides the necessary data and display the required basis. Output part refers to external lights along with music to flash. The designer can be decision of flash way of lights, the flash way has dynamic or static, or color or monochrome. We will talk about the concrete design of the three part:

1.1.3 Design of input part
Because of MCU just only deal with the disperse digital signal, but in real life is more analog signal especially music signal range as 200Hz to 15KHz, which is the practicality of the system to table a proposal and requests. To achieve of disperse of analog for input data. This is to be an easy job to the modulus is more and more mature conversion technology. That is to say we must through the analog-to-digital converter (ADC) converts the input music analog signal to digital, and then into the microcontroller.

1.1.4 MCU process
Input to MCU data stored in the microcontroller’s data store(MCU data memory). Because of display part ask the light flash along with music beat. But the music belongs to the audio signal. corresponding to the beat of the music and audio signal frequency, so in order to achieve unity displayed with the beat, it is necessary to discrete digital signal , digital signal processing technology and audio signal frequency is currently the most commonly used is the discrete Fourier transform(DFT).

1.1.5 output display part
Design idea is relatively simply and straightforward for output display part. which is easy to implement. Consider to the frequency range of the actual music signal is 200Hz ~ 15KHz,Through the A / D converter after, sampling the analog frequency will correspond to the digital frequency K value , i.e., a certain range of values ​​K (where K the maximum value is carried out by DFT points). This system is realized by using different colors of the diode consists of a 5 x 7 dot matrix. With 7 diodes of different colors to represent different frequency, which the digital frequency value of K is divided into 7 equal parts, each segment of K value with diode represents a color. Each color diodes have 5 used to represent the amplitude, the amplitude is divided into 5 sections to achieve different. Because the signal amplitude of the MCU 5V maximum, when the range of 0 ~ 1V, the corresponding frequency diode light one; is 1 ~ 2V, bright two diodes; for 2 ~ 3V, bright three diodes; for 3 ~ 4V, bright four diodes; 4 ~ 5V, bright five diodes.
The above is a general idea of the topic(LED contrller),

Chip On Board, COB
process is First using a thermal conductivity covering the wafer placed on surface of substrate (usually with the epoxy resin mixed with silver particles). Then the silicon wafer directly placed on the surface of the substrate, a silicon wafer is firmly fixed to the base with heat treatmen Final, create a electrization connection between the surface of substrate and silicon wafer with way of wire welding. Bare chip technology mainly has two forms: one is the COB technology, the other is the flip chip technology (Flip Chip).The board chip packaging (COB), a semiconductor chip connection mounted on the circuit print board, electrical connects in surface of substrate and chip whit suture method for lead. covered with resin to ensure reliability. Although COB is the most simple chip mounting technology, but the packaging desity if not as good as than TAB and a welding technology.
COB mainly welding method: (1) hot pressure welding
The metal wire and the welding pressure welding together by heat and pressure. Its principle is to add pressure and add heating, makes the welding zone to produce plastic deformation and destroy the oxidation layer of pressure welding on the interface,so that the inter atomic appeal to “bond” purposes, in addition, two metal uneven interface to add heating and add pressure can make mutually embedded compression and incrustation for the the top and bottom metal.This technique is generally used for chip on glass plate COG.
(2) for ultrasonic welding
Ultrasonic welding can be generated energy by ultrasonic generator,through the transducer in the ultra high frequency magnetic field induction,rapid expansion to generate elastic vibration, make a corresponding vibration for the chopper, driven the AI metal layer as the pad (AI film) rapid surface friction. Then the AI wire and AI membrane surface of the plastic deformation, the deformation and failure of the oxide layer, make the two pure metal surface in close contact to interatomic bonding, and come into being wedge. The main welding material for aluminum wire bonding.

(3) wire welding
Ball welding technology is the most representative welding technology in wire bonding. Because the semiconductor packaging and triode package use wire ball bonding welding. And it is convenient in operation, flexible, solid solid solder joint(AU wire diameter 25UM of weld strength is generally 0.07 ~ 0.09N / point) and no direction, the welding speed can be up to 15 point / sec. Wire bonding is also called thermal (pressure) sonic welding main bonding materials for gold (AU) wire welding, Having the shape of a sphere, also called the solder ball

The first step: expanding crystal。 Expansion machine will uniform expand the whole LED wafer thin film.the attachment of LED grains are closely arranged in a thin film on the surface opened, easy thorn crystal.

Step two: gum. The expansion of good crystal crystal ring put in gum machine(gum machine has been scraping silver layer), back silver paste. Point Silver. LED chip is suitable for bulk.(Dispenser)using the appropriate amount of silver paste on the PCB printed circuit board.

third step: the expanding ready Silver Crystal Ring crystal planes into the thorns,the operator used the microscope LED wafer crystal pen with barbed spines are on
The printed circuit board PCBunder the microscope the

fourth step: Put the thorn good crystal of PCB circuit print board into heat cycling constant temperature oven for a period of time. Wait for the silver slurry is solidified out(not for a long time, otherwise LED chip coating will be roasted yellow, oxidizing, difficult to bonding ). LED chip bonding is necessary above step, the IC chip bonding is not necessary above step.

fifth step: sticking chip. using the (Dispenser) place amount of Red glue on PCB the circuit print board IC position。Then put the IC into correct on red plastic or vinyl with anti-static devices (vacuum suction pen or sub).
The sixth step:drying. The good die stick need to constant temperature for a period of time on hot circulating oven big plane. Can also to naturally cure (but time is longer).
The seventh step: bonding(wire).connect of wire between the wafer (LED grain or IC chip) and PCB board corresponding to pad via aluminum wire bonder machine. This is wire of welding for COB.

eighth step: Pretest。 Using profession test tools(according to difference purpose to choice difference tools )to check out the COB board, will not be qualified to repair。

ninety  step: dispensing。The dispenser will deploy a good amount of A B venue to the LED grain bonding, IC with black plastic package, then base on the require of customer will package.

tenth step: curing. The sealed plastic PCB printed circuit board placed in an oven heated to stand the heat cycle, the requirements can be set according to different drying times.

eleventh step: after the test. The packaged PCB printed circuit board with special tool for the detection of electrical performance test, to distinguish good or bad. compare of other technology of package, The COB technology price is low cost(just only for the same chip about 1/3), space saving, technology maturity However, any new technology can not be perfect at first appear,