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. What is virtual pixel, real pixel

Real and virtual-pixel screen is the corresponding.

Simply, real pixel is each LED of three red-green-blue LED which constitute a screen display is only involved in the use of an imaging pixel, in order to obtain sufficient brightness

Virtual screen is to use software algorithms to control the LED of each color to participate in the final number of adjacent pixels of the image, making the lamp with less LED to achieve greater resolution, it can increase about four times resolution.

As we all know, the largest cost is Led chip for Led display, one of our target is that we can save the cost but do not less the brightness. The virtual technology is a development direction. The virtual technology is not a simple tube to participate in imaging, it impact much for the brightness, gray. It requires the control system coordinate with the driver chips, to use the software algorithms and driver chips to combine response time, to save the Led cost but do not less the brightness.

Ⅱ.LED Display Maintenance Procedures

1. Control system
1) The entire screen is not bright or grid
Control of the host open whether or not
Communication line is plugged or not
Sending card has been plugged or not
The data line of multimedia card, capture card, sending card is connected well or not.
The switch position of JP1 or JP2 card is not ok¡±,open the host
The communication line plugged well
To re-insert the sending card
Connect the lines well of the multi-media card, collection card, sending card.
Adjusting the JP1, JP2 switch location
The protection of a computer monitor is good or not or display screen is black or blue. (Synchronous Screen)

2) Every time when start LED control system is not able to find COM port to send data between the signal,the acquisition card line is not connected or the computer COM itself is defective. Connected to the data line or replace the computer

3) The whole screen shake or double image, ” to check the data line between the computer and screen.
Check the DVI cable between multimedia card and sending card
“Sending card is defective”please reinsert or replace the signal cable, to reinforce the port of DVI cable, or replace the sending card.

2. Drive part
1) Module can not light
Horizontal direction of few modules do not light, check the normal and abnormal module cable connection is well or not.
Or 245 chip is ok or not.
Vertical direction of few modules do not light, check the power supply of this line is ok or not.
+5V or GND is supplied or not.
+5V or GND is short-circuit or not

2) The horizontal direction of modules or the corresponding module is not bright or abnormal display
To check the foot of corresponding module is pin-line signal leakage or welding, To check the signal on the line, the next is no welding or resistance welding leakage.

3) Two lines of one modules is bright at the same time(one of lines is normal, the other lines is bright all the time when display text.
Please check if corresponding two lines is short-circuit or not.

4) The first half or the second half , red or green do not light or do not display properly, it is lack of color for each module, please check 245 R.G B output is ok or not.
Check the normal output of 595 feet and abnormal 595 feet is passed or not
To see whether input feet is ok or GND, +5 V is short-circuit or not.

 Ⅲ. LED Display Screen FAQ and solution

1. Whole screen does not work (black screen)
(1) Check power supply
(2) Check signal connection (cat5,DVI cable) (synchronous screen)
(3) If synchronous screen, check the green led of sending card and receiving card whether it is twinkling or not.
(4) Check the monitor of PC whether it is protected as black,or screen display area is black or pure blue. (synchronous screen)

2.Whole LED module does not work(black module)
(1) Successive modules in horizontal do not work, please check the ribbon cable between the normal unit module and unnormal unit module whether it is connectted or not, or replace the first module from right side when facing the screen.
(2) Successive moudels in vertical do not work,please check the power supply of all the modules.

3.One row lamps of module does not work.
(1) Check this row whether connecting to output pin of 4953.
(2) Check 138 encoder.
(3) Check 4953.
(4) Check Vcc and GND of 4953.
(5) Check output of 74HC138 and 4953’s controlling pin whether connectted or not.

4.Unit module doesn’t work.
(1) Check 595 normal or not.
(2) Checking the up and down moudle corresponded common pin connect or not.
(3) Check 595 output pin to moudle pin connect or not.

5.One color lacked in half or whole LED panel.
(1) Check 245 R, G, B data output.
(2) Check normal 595 output pin and unmormal 595 input pin whether it is connectted well or not.

Ⅳ. LED Display Purchasing Guidance

What need to be considered when deciding the size of the LED display?
1) What is the minimum watching distance and then decide the size of the display according to the actual space.
2) Pixel pitch and resolution
3) The space for installation and maintainence
4) The angle from the display to the ground

What content do you want to show?
1) TEXT. Based on the size of the text and the resolution need.
2) Normal video.320 x 240 dot matrix
3) Number standard DVD display: ≥640 x 480 dot matrix
4) Complete computer video: ≥800 x 600 dot matrix

What are the requirements for the led display brightness according to the Environmental brightness?
General requirement for the brightness are as follows:
1) Indoor:>800CD/M2
2) Semi indoor: >2000CD/M2
3) Outdoor( facing North):>4000 CD/M2
4) Outdoor( facing south):>8000CD/M2

Requirement for the brightness of RED, GREEN and BLUE when show white.
RED, GREEN, BULE plays different role when showing white. The fundamental reason is due to the human eye retina has different feeling for different wavelengths of light. After a large number of experiments and rest, we come to the following ratio for the reference: Simple red-green-blue light ratio: RGB 3:6:1 accurate brightness ratio: 3.0:5.9:1.1

Why the high quality led screen requires pure green led?
In the production of the led screen, we should use the trichromatic LED lamp with high lunimous efficiency and rich color. So that in the chromaticity diagram of color in the triangle area and near the tongue as far as possible in the color spectrum curve, to meet the needs of rich color and the issue of sufficient brightness and the tongue-shaped curve for the 515nm wavelength of light best, so high-end LED screen selected wavelength close to 515nm pure green LED light pipes, such as the choice of 520nm, 525nm or 530nm wavelength LED light tube.

When you know the brightness and the resolution, how to calculate the brightness of a single led?
Caculate as follows: (2R1G1B)
Red LED brightness: brightness(CD)/ M2/dots/M2 x 0.3/2
Green LED brightness: brightness(CD)/M2/dots/M2 x 0.6
Blue LED brightness: brightness(CD)/M2/dots/M2 x 0.1
E.G : 2500dots/sqm, 2R1G1B, brightness per sqm is 5000 CD/M2
so red led brightness is as follows: 5000/2500 x 0.3/2=0.3 green LED brightness :5000/2500 x 0.6/2=1.2 blue led brightness:5000/2500 x 0.1=0.2
brightness of a single pixle :0.3 x 2+1.2+0.2=2.0 CD

Why choose DVI graphics card standard interface?
1) DVI graphics card interface is in line with international standards for the computer interface
2) No need to open the chassis, can be easily installed;
3) High-memory and strong dynamic screen display capability
4) Good compatibility of hardware and software
5) Supports all operating systems and application software
6) High-volume production, low cost, easy maintenance.

Can the display be controlled with Laptop?
no, Laptop’s graphics card is built-in, there is no DVI port, can not be achieved in connection with the control system.
What are the differences of NICHIA chip and othe domestic led chip except price?
1) Chip: Nichia company produce their chip independedtly while the domestic company always use the chips from America or Taiwan.
2) Packaging: Nichia company packaging independently, no branch factory in China.But for the domestic chip, there are many factories do the packaging.
3) Consistency: for the Nichia led in one lot, the wavelength has little difference, But for the domestic led, consistency is relatively poor
4) Life span: Nichia led has relarively longer life span, Domestic led attenuate faster.

Indoor full-color module and SMD full-color display, What is the difference?
1) light-emitting parts: the module full color screen display is generally green, the price of pure green module is higher; SMD generally use pure green chip;
2) image quality: full-color pixel module looks rough, low brightness and there always mosaic;SMD full color led display has better consistency and higher brightness;
3) maintenance: full-color module is not easy to maintain. The cost of replacing the entire module is high; the SMD full-color module is easy to maintain, maintenance can be carried out by replacing a single lamp;

Can the SMD used for outdoor display? Why?
Yes. Outdoor screen has high demand of installation and structure, now SMD LED able to adapt to the harsh outdoor environment; and SMD display can meet brightness requirements of outdoor display

Why it takes longer time to produce outdoor display?
1) procurement of raw materials: purchasing the led takes long time, specially when you have to import , it takes even longer time.
2) the complexity of production process: subject to PCB design, production casing, irrigation plastic, tune white balance, etc.;
3) the structure of demanding: the general design for the box, need to consider wind, rain, lightning and so on.

How to help customers choosing the right display?
1) what need to be shown?
2) viewing distance and viewing angle
3) resolution requirement
4) requirement of environment
5) cost control

What is the genaral ratio of width and hight for the display?
Picture and text: subject to what you want to show.
Video display: normmaly it is 4:3 or near this proportion. Ideal proportion is 16:9

How many pixels can one control system control?
Communications screen Card A: single color, dual color 1024 x 64
Communications screen Card B: single color: 896×512, two color;896x 256
DVI dual color display:12801×768. DVI full color led display: 1024×512

what are the factors to consider when design the size of the screen?
when design the size of the display, there are 3 factors very important.
1) the needs of displaying content
2) space limitation
3) according to the module size and resolution

More than 10 kilowatts buck should start screen equipment.
Communication requirements: communication distance is long for the definition of communication.
To be installed to display the type of communication lines used by the length of the standard to install communications lines.
The prohibition of communication lines and power lines in the same pipe line alignment.
Installation requirements: about the level of the installation screen does not allow backward – to the installation of lifting up and down adjustment rod – wall to be installed before installing forward off hook – landing position to increase support for the installation of bolts.

Indicators display power consumption and power requirements of what?
Screen is divided into the average power consumption of the power consumption and maximum power consumption. Also known as the work of the average power consumption is usually the actual power consumption. Power consumption is the largest start-or full-bright at the time of extreme circumstances, such as power consumption, maximum power is AC power supply (wire, switches, etc.) must take into account the elements. Average power consumption is generally the largest power of 1/3. Display is a large-scale precision electronic equipment, safe use and reliable to work, its power supply input AC220V or AC220V power supply connected to the computer¡¯s input must be grounded. Note: The computer¡¯s power supply input AC220V grounding terminal connected with the computer chassis.

Display of the installation requirements?
Power requirements: power supply wiring should be in the body size of the screen 220V electricity power supply, FireWire grounding line 0 line; 380V electricity supply, the three 10-line ground line of fire line; the front lines with the 0-line the same wire cross-sectional area; more than 10 kilowatts buck should start screen equipment. Communication requirements: communication distance is long for the definition of communication. Installed to display the type of communication lines used by the length of the standard to install communications lines. Prohibition of communication lines and power lines in the same pipe line alignment. Installation requirements: about the level of the installation screen, do not allow the dumping after the lifting rod to regulate the installation of up and down before the installation of wall mounted hook falling forward landing position to increase support for the installation of bolts.

What issues should be considered for outdoor screen design and installation ?
The main issues of outdoor screens are as follows:
1) Screen installed in the outdoor sun and rain often, the wind dust cover, the work environment. Electronic equipment to be wet or damp can cause serious short-circuit or even fire, and even lead to failure of fire, resulting in losses;
2) Screen may be caused by strong electric lightning attack Magnetic;
3) Significant changes in ambient temperature. Display the work itself should have a certain amount of heat, if the ambient temperature and the heat is too high and non-performing, integrated circuits may not work correctly, and even burned down, so that shows that the system does not work;
4) Wide audience, require line-of-sight distance requirements of wide field of vision; ambient light changes, in particular, may be subject to direct sunlight.

The special requirements of the above, outdoor display must be:
1) Screen body and the screen body and architecture must be strictly waterproof junction leakage; screen body in order to provide good drainage measures, in the event of a smooth water emissions; (2) and building on the screen to install lightning protection devices. The main screen and the casing to maintain a good grounding, grounding resistance is less than 3 ohms, so that high current caused by lightning discharge in time;
3) The installation of ventilation to cool the screen so that the internal body temperature of -10 ℃ ~ 40 ℃ between. Screen behind the body above the axial fan is installed, from the heat;
4) Choice of working temperature -40 ℃ ~ 80 ℃ industrial level integrated circuit chip, the temperature is too low to prevent the winter so that the screen could not be activated. ;
5) In order to ensure a strong ambient light in the case of remote visualization, we must choose ultra-high brightness light-emitting diodes;
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