53 tips about LED displays that customers care about most

May 17,2021| LED Knowledge

1. What is a surface mount module? What are the advantages and disadvantages?
Surface mount is also called SMT. The SMT packaged lamp is soldered on the surface of the PCB board, and the lamp pins do not need to pass through the PCB board. Modules composed of this process are called surface mount modules.
Advantages: good display effect, high pixel density, suitable for indoor viewing
Disadvantages: the brightness is not high enough, and the heat dissipation of the lamp itself is not good enough


2. What is a sub-surface mount module, and what are the advantages and disadvantages?

Sub-surface mount is a product between DIP and SMT. The package surface of the LED is the same as that of SMT, but its positive and negative pins are the same as DIP. They are also soldered through the PCB during production. The advantage is high brightness. , The display effect is good. Disadvantages: the process is complicated and the maintenance is difficult.


3. What is three in one, and what are the advantages and disadvantages?
Refers to the SMT lamps packaged with three different colors of RGB LED chips arranged vertically together at a certain pitch.

Advantages: good effect Disadvantages: complex process, difficult maintenance, high cost


4. What is the difference between an indoor module full-color screen and a patch full-color screen?
a. Light-emitting part: The display module of the module full-color screen is generally yellow-green, the pure green module is generally more expensive, and the SMD full-color screen generally uses a pure green tube core
b. Display effect: module full-color screen pixels have a coarser visual perception, lower brightness, and are prone to mosaic phenomena. SMD full-color screens have better alignment and higher brightness.
c. Maintenance: The full-color module is not easy to maintain, the replacement cost of the whole module is higher, the full-color patch is easy to maintain, and the single lamp can be repaired.

5. Why is the production cycle of outdoor screens relatively long?
1. Raw material procurement: The procurement cycle of LED tubes is relatively long, especially for imported dies, the order cycle takes 4-6 weeks
2. Complex production process: need to go through PCB design, cover production, glue filling, white balance light adjustment
3. Combination of structural requirements: generally box design, need to consider wind, rain, lightning protection

6. What is a synchronous system and what is an asynchronous system?

Synchronous and asynchronous are relative to the computer. The so-called synchronous system refers to the led display control system that is displayed on the display screen and the computer monitor synchronously. The asynchronous system refers to the display data edited by the computer and stored in the display screen in advance. In the control system, the policy display of the LED display screen will not be affected after the computer is shut down.


7. What is a real pixel?
It refers to the 1:1 relationship between the physical pixels on the display screen and the actual displayed pixels. How many points are actually displayed on the display screen can only display image information.

8. What is a virtual pixel
The virtual pixel refers to the 1:N (N=2,4) relationship of the number of physical pixels of the display screen. The image pixels it can display are 2 or 4 times more than the actual pixels of the display screen.

9. What is a perspective? What is the viewing angle? What is the best perspective?
The viewing angle is when the brightness of the viewing direction drops to 1/2 of the normal brightness of the LED display, the angle formed by the two viewing directions and the normal direction on the same plane is divided into horizontal and vertical angles. The viewing angle is just right. See the direction of the image content on the display screen, and the angle formed by the normal line of the display screen. The best viewing angle is that you can just see the content on the display screen without color cast, and the clearest direction of the image content is formed by the normal line. angle.

10. How to choose the right display?
1. Need for display content 2. Confirmation of visual distance and viewing angle 3. Requirements for screen resolution 4. Requirements for installation environment 5. Cost control

11. There are three factors in the design of the screen body:

1. The need to display content 2. The space conditions of the venue 3. The size of the display unit template (indoor screen) or large pixels (outdoor screen)


12. What is a sub-surface mount module? What are the advantages and disadvantages?

Sub-surface mount is a product between DIP and SMT. The packaging surface of its LED lamp is the same as that of SMT, but its positive and negative pins are the same as DIP. It is also welded through the PCB during production. The advantages are: high brightness and good display effect, but the disadvantages are: complicated process and difficult maintenance.

13. What is 3 in 1? What are its advantages and disadvantages?
It means that the SMT lamps packaged with three different colors of RGB LED chips are arranged vertically together at a certain interval. This not only has all the advantages of 3 in one, but also solves the various shortcomings of 3 in one: complex process and difficult maintenance .

14. What is three in one?
It is to vertically juxtapose three kinds of RGB SMT lamps with independent packages according to a certain interval. This not only has the advantages of 3 in one, but also solves the various shortcomings of 3 in one.

15. What is a dual-color, pseudo-color, full-color display?
Different color LEDs can form different display screens. Dual primary colors are composed of red, green or yellow and green. Pseudo-color is composed of three different colors of red, yellow-green and blue. Full color is composed of red. , Pure green, pure blue three different colors.

16: What is luminous brightness?
The light intensity emitted by a unit area of an LED display is in CD/square meter, which is simply the intensity of light emitted by one square meter of display.

17: What is the brightness level?
The level of manual or automatic adjustment between the lowest brightness and the highest brightness of the entire screen.

18. What is gray scale?
Under the same brightness level, the number of technical processing levels from the darkest to the brightest of the display screen.

19. What is the maximum brightness?
Under a certain environmental illuminance, each primary color of the LED display screen is at the maximum brightness and maximum gray level.

20. What is moiré?
That is, when shooting a full-color LED display at work, some irregular water ripples will appear on the screen of the LED display. These water ripples are called "moir patterns" in physics.

21. What is a PCB?
PCB is (abbreviation of printed circuit board) printed circuit board.

22. What is the cell board specification?
Refers to the size of the cell board, usually expressed by the expression of the cell board length multiplied by the width, in millimeters. (48×244)

23. What is the resolution of the unit board?
Refers to the number of pixels in a unit board, usually expressed by the expression of the number of rows of pixels of the unit board multiplied by the number of columns. (Eg: 64×32)

24. What is BOM?
BOM is (abbreviation of bill of material) bill of materials.

25: What is white balance and what is white balance adjustment?
What we call white balance refers to the balance of white, that is, the balance of the brightness ratio of the three colors of RGB; the adjustment of the brightness ratio of the three colors of RGB and the white coordinate is called white balance adjustment.

26: What is contrast?
Under a certain environmental illumination, the ratio of the maximum brightness of the LED display to the background brightness.

27. What is color temperature?
When the color emitted by the light source is the same as the color of the black body at a certain temperature, the temperature of the black body is called the color temperature of the light source.

28. What is chromatic aberration?
The LED display screen is composed of red, green and blue to produce various colors, but these three colors are made of different materials, the viewing angle is different, and the spectral distribution of different LEDs are changed. These differences that can be observed are called For the color difference. When observing the LED from a certain angle, its color changes. The human eye's ability to judge the color of a real picture (such as a movie picture) is better than observing a picture produced by a computer.

29. What is the frame change frequency?
The number of times the display screen information is updated per unit time.

30. What is the refresh frequency?
The number of times the display screen is repeatedly displayed on the display screen in unit time.

31: What is the perspective? What is the viewing angle? What is the best perspective?
The viewing angle is when the brightness of the viewing direction drops to 1/2 of the brightness of the normal line of the LED display screen. The angle formed by the two observation directions of the same plane and the normal direction is divided into horizontal and vertical viewing angles; the viewing angle is the direction in which the image content on the display can be seen, and the angle formed by the normal of the display. The best viewing angle is to be able to just see the content on the display, and not flat, the angle formed by the clearest direction of the image content and the normal.

32: What is the best viewing distance?
It is the vertical distance of the clearest position of the image content relative to the screen body that can just see the content on the display screen completely, and is not flat.

33: What is the point of out of control? How many kinds?
For pixel points whose light-emitting state does not meet the control requirements, out-of-control points are divided into three types: blind spots (also known as dead spots) and constant bright spots (or dark spots).

34. What is a static drive:? What is a scan driver? What is the difference between the two?
The "point-to-point" control from the output pin of the driver IC to the pixel point is called static drive, and the "point-to-column" control from the output pin of the driver IC to the pixel point is called scan drive. It requires a row control circuit: It can be clearly seen from the driver board that static driving does not require a line control circuit, which is costly, but has good display effect, good stability, and low brightness loss; scan driving requires a line control circuit, but the cost is low. The effect is poor, and the brightness loss is too great.

35. What is constant current drive? What is constant voltage drive?
Constant current refers to the constant output current value specified in the working environment allowed by the driver IC: constant voltage refers to the constant output voltage value specified in the working environment allowed by the driver IC.

36. What is the general aspect ratio of LED displays?
Graphic screen: Determined according to the displayed content; Video screen: Generally 4:3 or close to 4:3; The ideal ratio is 16:9.

37. The number of points that a set of control system can control?
Communication screen card A: monochrome, dual color 1024×64; communication screen card B: monochrome: 896×512 dual color: 896×256; DVI dual color screen: 1280×768; DVI full color screen: 1024×512.

38. What is nonlinear correction?
If the digital signal output by the computer is displayed on the LED display without correction, there will be color distortion, so in the system control circuit, the original computer output signal is calculated by a non-linear function to obtain the signal required by the display. Because of the nonlinear relationship between the front and rear signals, we often call it nonlinear correction.

39. What is the rated working voltage? What is the working voltage? What is the supply voltage?
The rated working voltage refers to the voltage when the voltage is used for normal work; the working voltage refers to the voltage value of the electrical appliance in the rated voltage range and when working normally: the power supply voltage is divided into AC and tributary power supply voltages. Our actual AC power supply voltages are both AC220V-240V, DC power supply voltage is generally 5V DC12V, solar power supply is generally 12V.

40. What is color distortion?
It refers to the difference between the display of the same object in the natural world and the display on the human eye.

41: What is a synchronous system and what is an asynchronous system?
Synchronous and asynchronous are relative to the computer. The so-called synchronous system refers to the LED display control system that displays the content displayed on the display screen and the computer monitor synchronously; the asynchronous system refers to the pre-stored display data edited by the computer In the display control system, the normal display of the LED display will not be affected after the computer is turned off. Such a control system is an asynchronous control system.

42. What is blind spot detection technology?
Through the upper software and the underlying hardware, the blind spots (LED open and short) on the display can be detected, and a report can be formed to tell the LED screen manager. Such a technology is called blind spot detection technology.

43. What is power detection?
Through the upper software and the underlying hardware, the working conditions of each power supply on the display screen can be detected, and a report can be formed to tell the LED screen manager. Such a technology is called power detection technology.

44. What is brightness detection? What is brightness adjustment?
The brightness in the brightness detection refers to the brightness of the environment where the LED display is located. The light sensor detects the brightness of the environment where the display is currently located. This detection method is called brightness detection; the brightness mentioned in the brightness adjustment refers to the LED display The emitted brightness and the detected data are fed back to the LED display control system or control computer, and then the brightness of the display is adjusted according to this data, which is called brightness adjustment.


45. What is a real pixel? What is a virtual pixel? What kinds of virtual pixels are there? What is pixel sharing?
Real pixels refer to the 1:1 relationship between the number of physical pixels on the display screen and the actual displayed pixels. How many points the display screen actually has, only how many image information can be displayed. Virtual pixel refers to the 1:N (N=2, 4) relationship between the number of physical pixels on the display screen and the number of pixels actually displayed. It can display image pixels 2 or 4 times more than the actual pixels on the display screen; virtual Pixels can be divided into software virtual and hardware virtual according to the virtual way: according to the multiple relationship, they are divided into 2 times virtual and 4 times virtual. According to the row of lights on a module, they are divided into 1R1G1B virtual and 2R1G1B virtual.

46. What is remote control? Under what circumstances?
The so-called long-distance is not necessarily long-distance. The remote control includes the main control terminal and the controlled terminal in a local area network, but the space distance is not far; and the main control terminal and the controlled terminal are within a relatively long space distance. The customer requires or the customer control position exceeds the optical fiber directly. Control the distance, then use remote control.

47. What is fiber optic transmission? What is network cable transmission?
Optical fiber transmission uses transparent glass fiber to convert electrical signals into optical signals, while network cable transmission uses metal wires to directly transmit electrical signals.

48. Under what circumstances are network cables used? When to use optical fiber?
When the wiring distance between the display screen and the control computer is less than 100 meters, use a network cable for transmission; when the distance between the two is less than 500 meters and greater than 100 meters, use a multi-mode fiber, and when the distance is greater than 500 meters, use a single-mode fiber.

49. What is LAN control? What is internet control?

In the local area network, one computer is used to control another computer or connected to other external devices. This control method is called local area network control. The main controller achieves the control purpose through the IP address of the controller in the INTERNET network, which is called the Internet. control.

50. What is DVI? What is VGA?
DVI is the abbreviation of Digital Video interface, that is, digital video interface. It is a digital video signal interface commonly used internationally.

51. What is a digital signal? What is a digital circuit?
Digital signal means that the value of the signal amplitude is discrete, and the amplitude value is limited to two finite values of 0 and 1. The circuit that processes and controls this western signal is called a digital circuit.

52. What is an analog signal and what is an analog circuit?
An analog signal means that the value of the signal amplitude is continuous in time; the circuit that processes and controls this signal is called an analog circuit.

53. What is a PCI slot?
PCI slot is based on PCI local bus (PEDPHERD component interconnect, week

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