1: What is LED?
LED is the abbreviation of light emitting diode. The “LED” in the display industry refers to the LED that can emit visible light
2: What is pixel?
The minimum luminous pixel of LED display has the same meaning as “pixel” in ordinary computer display;
3: What is pixel spacing (dot spacing)?
The distance from the center of one pixel to the center of another pixel;
4: What is the LED display module?
The smallest unit composed of several display pixels, which is structurally independent and can form an LED display screen. Typical is “8 × 8”、“5 × 7”、“5 × 8 “, etc., can be assembled into modules through specific circuits and structures;
5: What is DIP?
DIP is the abbreviation of Double In-line Package, which is a dual in-line assembly;
6: What is SMT? What is SMD?
SMT is the abbreviation of Surface Mounted Technology, which is the most popular technology and process in the electronic assembly industry at present; SMD is the abbreviation of surface mounted device
7: What is the LED display module?
The basic list determined by the circuit and installation structure, with display function, and able to realize display function through simple assembly
8: What is LED display?
Display screen composed of LED device array through certain control mode;
9: What is the plug-in module? What are the advantages and disadvantages?
It refers to that the DIP packaged lamp passes the lamp pin through the PCB board and fills the tin in the lamp hole through welding. The module made by this process is the plug-in module; The advantages are large viewing angle, high brightness and good heat dissipation; The disadvantage is that the pixel density is small;
10: What is the surface pasting module? What are the advantages and disadvantages?
The SMT is also called SMT. The SMT-packaged lamp is welded on the surface of the PCB through the welding process. The lamp foot does not need to pass through the PCB. The module made by this process is called SMT module; The advantages are: large viewing angle, soft display image, high pixel density, suitable for indoor viewing; The disadvantage is that the brightness is not high enough and the heat dissipation of the lamp tube itself is not good enough;
11: What is the sub-surface sticker module? What are the advantages and disadvantages?
The sub-surface sticker 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 that of DIP. It is also welded through PCB during production. Its advantages are: high brightness, good display effect, and its disadvantages are: complex process, difficult maintenance;
12: What is 3 in 1? What are its advantages and disadvantages?
It refers to packaging LED chips of different colors R, G and B in the same gel; The advantages are: simple production, good display effect, and the disadvantages are: difficult color separation and high cost;
13: What is 3 and 1? What are its advantages and disadvantages?
3 in 1 was first innovated and used by our company in the same industry. It refers to the vertical juxtaposition of three independently packaged SMT lamps R, G and B according to a certain distance, which not only has all the advantages of 3 in 1, but also solves all the disadvantages of 3 in 1;
14: What are dual primary color, pseudo-color and full-color displays?
LED with different colors can form different display screens. The double primary color is composed of red, green or yellow-green colors, the false color is composed of red, yellow-green and blue colors, and the full color is composed of red, pure green and pure blue colors;
15: What is the meaning of luminous intensity (luminosity)?
Luminous intensity (luminosity, I) is defined as the luminous intensity of a point light source in a certain direction, that is, the amount of light emitted by the luminous body in a unit time, also referred to as luminosity. The common unit is candela (cd, candela). An international candela is defined as the luminosity emitted by burning a candle made of whale oil at 120 grams per hour. One gram of cold is equal to 0.0648 grams
16: What is the unit of luminous intensity (luminosity)?
The common unit of luminous intensity is candela (cd, candela). The international standard candela (lcd) is defined as the luminosity of 1/600000 in the direction perpendicular to the blackbody (its surface area is 1m2) when the ideal blackbody is at the platinum freezing point temperature (1769 ℃). The so-called ideal blackbody means that the emissivity of the object is equal to 1, and the energy absorbed by the object can be completely radiated, so that the temperature remains uniform and fixed, The exchange relationship between the international standard candela and the old standard candela is 1 candela=0.981 candle
17: What is luminous flux? What is the unit of luminous flux?
Luminous flux（ φ） The definition of is: the energy emitted by a point light source or non-point light source in a unit time, in which the visual person (the radiation flux that people can feel) is called luminous flux. The unit of luminous flux is lumen (abbreviated as lm), and 1 lumen (lumen or lm) is defined as the luminous flux passed by an international standard candle light source in the unit solid arc angle. Since the whole spherical area is 4 π R2, the luminous flux of one lumen is equal to 1/4 π of the luminous flux emitted by one candle, or the spherical surface has 4 π, so according to the definition of lumen, a point light source of cd will radiate 4 π lumens, that is φ (lumen)=4 π I (candlelight), assuming △ Ω is a small solid arc angle, the light flux △ in △ Ω solid angle φ， △ φ= △ΩI
18: What does one foot candle mean?
One foot-candle refers to the illuminance on the plane that is one foot away from the light source (point light source or non-point light source) and orthogonal to the light, which is abbreviated as 1 ftc (1 lm/ft2, lumens/ft2), that is, the illuminance when the luminous flux received per square foot is 1 lumen, and 1 ftc=10.76 lux
19: What is the meaning of one meter candle?
One meter candle refers to the illuminance on the plane one meter away from the light source of one candle (point light source or non-point light source) and orthogonal to the light, which is called lux (also written as lx), that is, the illuminance when the luminous flux received per square meter is 1 lumen (lumen/m2)
What does 20:1 lux mean?
Illuminance when the luminous flux received per square meter is 1 lumen
21: What is the meaning of illuminance?
Illuminance (E) is defined as the luminous flux accepted by the unit illuminated area of the illuminated object, or the luminosity accepted by the illuminated object per unit area in unit time, expressed in meter candles or foot candles (ftc)
22: What is the relationship between illuminance, luminosity and distance?
The relationship between illuminance, luminosity and distance is: E (illuminance)=I (luminosity)/r2 (square of distance)
23: What factors are related to the illuminance of the subject?
The illuminance of the object is related to the luminous intensity of the light source and the distance between the object and the light source, but not to the color, surface property and surface area of the object
24: What is the meaning of light efficiency (lumen/watt, lm/w)?
The ratio of the total luminous flux emitted by the light source to the electrical power consumed by the light source (W) is called the luminous efficiency of the light source
25: What is color temperature?
When the color emitted by the light source is the same as the color radiated by the blackbody at a certain temperature, the temperature of the blackbody is the color temperature
26: What is luminous brightness?
The light intensity per unit area of LED display screen, in cd/m2, is simply the light intensity per square meter of display screen;
27: What is the brightness level?
The level of manual or automatic adjustment between the lowest and highest brightness of the whole screen
28: What is gray scale?
At the same brightness level, the technical processing level of the display screen from the darkest to the brightest;
29: What is contrast?
It is the ratio of black to white, that is, the gradual gradation from black to white. The larger the ratio, the more gradation from black to white, and the richer the color representation. In the projector industry, there are two contrast testing methods. One is the full-open/full-close contrast testing method, that is, testing the brightness ratio of the full white screen to the full black screen output by the projector. The other is ANSI contrast, which uses the ANSI standard test method to test the contrast. The ANSI contrast test method uses 16-point black and white color blocks. The ratio between the average brightness of eight white areas and the average brightness of eight black areas is the ANSI contrast. The contrast values obtained by these two measurement methods are very different, which is also an important reason for the large difference in nominal contrast of products from different manufacturers. Under certain ambient illumination, when the primary colors of LED display screen are at the maximum brightness and maximum gray level
30: What is a PCB?
PCB is printed circuit board;
31: What is BOM?
BOM is the bill of materials (abbreviation of Bill of material);
32: What is white balance? What is white balance regulation?
By white balance, we mean the balance of white, that is, the balance of the brightness of R, G and B in the ratio of 3:6:1; The adjustment of brightness ratio and white coordinates of R, G and B colors is called white balance adjustment;
33: What is contrast?
The ratio of the maximum brightness of LED display screen to the background brightness under a certain ambient illuminance;
34: What is the frame change frequency?
The number of times the display screen information is updated per unit time;
35: What is the refresh rate?
The number of times the display screen is repeatedly displayed by the display screen;
36: What is wavelength?
Wavelength（ λ）： The distance between the corresponding points or the distance between the two adjacent peaks or valleys in the two adjacent periods during wave propagation, usually in mm
37: What is the resolution
The concept of resolution simply refers to the number of points displayed horizontally and vertically on the screen
38: What is perspective? What is the visual angle? What is the best perspective?
The angle of view is the angle between the two viewing directions on the same plane and the normal direction when the brightness of the viewing direction drops to 1/2 of the normal direction of the LED display. It is divided into horizontal and vertical perspectives; The viewable angle is the angle between the direction of the image content on the display screen and the normal of the display screen; The best angle of view is the angle between the clearest direction of the image content and the normal line;
39: What is the best sight distance?
It refers to the vertical distance between the clearest position of the image content and the screen body, which can just see the content on the screen completely without color deviation;
40: What is the point of losing control? How many?
Pixels whose luminous state does not conform to the control requirements; Out of control points are divided into: blind spot (also known as dead spot), constant bright spot (or dark spot), and flash point;
41: What is static drive? What is scan drive? What is the difference between the two?
The “point to point” control from the output pin of the driving IC to the pixel is called static driving; The “point to column” control from the output pin of the drive IC to the pixel point is called scanning drive, which requires a row control circuit; It can be clearly seen from the drive board that the static drive does not need line control circuit, and the cost is high, but the display effect is good, the stability is good, and the brightness loss is small; Scanning drive requires line control circuit, but its cost is low, display effect is poor, stability is poor, brightness loss is large, etc;
42: What is constant current drive? What is constant pressure drive?
Constant current refers to the current value specified in the design of constant output within the allowable working environment of the drive IC; Constant voltage refers to the voltage value specified in the design of constant output within the allowable working environment of the drive IC;
43: What is nonlinear correction?
If the digital signal output by the computer is displayed on the LED display screen without correction, color distortion will occur. Therefore, in the system control circuit, the signal required for the display screen calculated by the original computer output signal through a nonlinear function is often called nonlinear correction because of the nonlinear relationship between the front and back signals;
44: 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 electrical appliance works normally; Working voltage refers to the voltage value of the electrical appliance under normal operation within the rated voltage range; The power supply voltage is divided into AC and DC power supply voltage. The AC power supply voltage of our display screen is AC220V~240V, and the DC power supply voltage is 5V;
45: What is color distortion?
It refers to the difference between the human eye’s sense and vision when the same object is displayed in nature and on the display screen;
46: What are synchronous systems and asynchronous systems?
Synchronization and asynchrony are relative to what computers say. The so-called synchronization system refers to the LED display control system that the contents displayed on the display screen and the computer display are synchronized; Asynchronous system means that the display data edited by the computer is stored in the display screen control system in advance, and the normal display of LED display screen will not be affected after the computer is turned off. Such control system is asynchronous system;
47: What is blind spot detection technology?
The blind spot (LED open circuit and short circuit) on the display screen can be detected through the upper computer software and the underlying hardware, and a report can be formed to tell the LED screen manager. Such a technology is called blind spot detection technology;
48: What is power detection?
Through the upper computer software and bottom hardware, it can detect the working conditions of each power supply on the display screen and form a report to tell the LED screen manager. Such a technology is called power detection technology
49: What is brightness detection? What is brightness adjustment?
Brightness in brightness detection refers to the ambient brightness of the LED display screen. The ambient brightness of the display screen is detected by the light sensor. This detection method is called brightness detection; Brightness in brightness adjustment refers to the brightness of the light emitted by the LED display. The detected data is 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
50: What is a real pixel? What is virtual pixel? How many virtual pixels are there? What is pixel sharing?
Real pixel refers to the 1:1 relationship between the number of physical pixels on the display screen and the number of pixels actually displayed. The actual number of points on the display screen can only display the image information of how many points; Virtual pixel refers to the relationship between the number of physical pixels on the display screen and the number of actual pixels displayed is 1: N (N=2, 4). It can display two or four times more image pixels than the actual pixels on the display screen; Virtual pixels can be divided into software virtual and hardware virtual according to virtual control mode; It can be divided into 2 times virtual and 4 times virtual according to the multiple relationship, and it can be divided into 1R1G1B virtual and 2R1G1GB virtual according to the way of arranging lights on a module;
51: What is remote control? Under what circumstances?
The so-called long distance is not necessarily long distance. The remote control includes the main control end and the controlled end in a LAN, and the space distance is not far; And the main control end and the controlled end within a relatively long space distance; If the customer requests or the customer’s control position exceeds the distance directly controlled by the optical fiber, the remote control shall be used;
52: What is optical fiber transmission? What is network cable transmission?
Optical fiber transmission is to convert electrical signals into optical signals and use transparent glass fiber for transmission; Network cable transmission is the direct transmission of electrical signals using metal wires;
53: When do I use the network cable? When is optical fiber used?
When the distance between the display screen and the control computer
54: What is LAN control? What is Internet control?
In the LAN, one computer controls another computer or external devices connected to it. This control method is called LAN control; The master controller achieves the purpose of control by accessing the IP address of the controller in the Internet, which is called Internet control
55: 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 currently used internationally; The full English name of VGA is Video Graphic Array, that is, display graphics array. It is R, G and B analog output video signal interface;
56: What is digital signal? What is a digital circuit?
Digital signal means that the value of signal amplitude is discrete, and the amplitude representation is limited to 0 and 1; The circuit for processing and controlling such signals is called digital circuit;
57: What is an analog signal? What is an analog circuit?
Analog signal means that the value of signal amplitude is continuous in time; The circuit that processes and controls this kind of signal is called analog circuit;
58: What is a PCI slot?
PCI slot is an expansion slot based on PCI local bus (peripheral component expansion interface). PCI slot is the main expansion slot of the motherboard. By plugging different expansion cards, almost all external functions that can be realized by the current computer can be obtained;
59: What is an AGP slot?
Accelerated graphics interface. AGP is an interface specification that enables 3D graphics to be displayed at a faster speed on ordinary personal computers. AGP is an interface designed to transmit 3D graphics faster and more smoothly. It uses the main memory of an ordinary personal computer to refresh the image displayed on the display, and supports 3D graphics technologies such as texture mapping, zero buffering and alpha blending.
60: What is GPRS? What is GSM? What is CDMA?
GPRS is the General Packet Radio Service, a new bearer service developed on the existing GSM system, mainly used for radio communications; GSM is the abbreviation of the “GlobalSystemForMobileCommunication” standard (Global Mobile Communication System) uniformly launched by the European Commission for Standardization in 1992. It uses digital communication technology and unified network standards to ensure the quality of communication and can develop more new services for users. Code Division Multiple Access is a new and mature wireless communication technology based on spread spectrum technology;
61: What is the use of GPRS technology for display screens?
On the GPRS data network based on mobile communication, the data of our LED display is communicated through the GPRS transceiver module, which can realize remote point-to-point small amount of data transmission! Achieve the purpose of remote control;
62: What is RS-232 communication, RS-485 communication, and RS-422 communication? What are the benefits of each?
RS-232; RS-485; RS422 is a serial communication interface standard for computers
The full name of RS-232 standard (protocol) is EIA-RS-232C standard, in which EIA (Electronic Industry Association) represents the American Electronic Industry Association, RS (recommended standard) represents the recommended standard, 232 is the identification number, and C represents the latest revision of RS232
The signal level value of RS-232 interface is high, which is easy to damage the chip of interface circuit. The transmission rate is low, and the transmission distance is limited, generally within 20M.
RS-485 has a communication distance of tens of meters to thousands of meters. It uses balanced transmission and differential reception. RS-485 is very convenient for multi-point interconnection.
RS422 bus, RS485 and RS422 circuits are basically the same in principle. They are sent and received in differential mode, and do not need digital ground wire. Differential operation is the fundamental reason for the long transmission distance at the same rate, which is the fundamental difference between RS232 and RS232, because RS232 is single-ended input and output, and at least digital ground wire is required for duplex operation. The sending line and receiving line are three lines (asynchronous transmission), and other control lines can be added to complete synchronization and other functions.
RS422 can work in full duplex without affecting each other through two pairs of twisted pairs, while RS485 can only work in half duplex. Sending and receiving cannot be carried out at the same time, but it only needs one pair of twisted pairs.
RS422 and RS485 can transmit 1200 meters at 19 kpbs. Devices can be connected on the new transceiver line.
63: What is ARM system? For the LED industry, what is its use?
ARM (Advanced RISC Machines) is a company specialized in the design and development of chips based on RISC (Reduced Instruction Set Computer) technology. It can be considered as the name of a company, the general name of a class of microprocessors, and the name of a technology. The signal control and processing system based on the CPU with this technology is called ARM system. The LED special control system made of ARM technology can realize asynchronous control. The communication modes can include peer-to-peer network, LAN, Internet, and serial communication. It contains almost all PC interfaces;
64: What is a USB interface?
The English abbreviation of USB is Universal Serial Bus, which translates into Chinese as “Universal Serial Bus”, also known as Universal Serial Interface. It can support hot plugging and can connect up to 127 PC external devices; There are two interface standards: USB1.0 and USB2.0
Post time: Feb-18-2023