The advantages and disadvantages of LED display _LED the main functions of the display
Advantages of LED display
1. No seams
The unit of the LED display is the unit board, which is distributed with different sizes, different spacing, different number of lamp beads, this lamp bead is packaged by three color chips, and the light is controlled by the chip behind the unit board. If you want to assemble into a large screen, you only need to splice multiple unit boards together, and it has no splicing obstacles, and there is no seamless seam between the boards and boards, and there is no border like the LCD splicing screen, and naturally there is no seam trouble.
2. Waterproof and sunscreen
The special composition architecture ensures that the LED display can reach the level of waterproof and sunscreen, so we see that some outdoor displays are LED.
3. High brightness and adjustable
The brightness of the LED display can be freely adjusted to meet the display needs of different lights, such as outdoor facing the sun and facing away from the sun, its brightness is completely different, in order to ensure that the screen is clearly visible, it is necessary to adjust its brightness.
Disadvantages of LED display
1. Low resolution
The resolution of the LED display is much lower than the resolution of the LCD splicing screen, even if its minimum spacing product its resolution can not be compared with the LCD splicing screen, so the most direct consequence is that the LED will have a mosaic phenomenon when displaying the image, and the text will be composed of small squares when looking closely, and the picture clarity is worse.
2. Low contrast
Low contrast will lead to the light and dark and level of the picture is not rich enough, so the picture presented is not good, which is not as good as the LCD splicing screen.
3. High after-sales rate
The lamp beads of the LED display will fall off, dead lights and other phenomena, and they are relatively frequent, which increases the after-sales rate and costs.
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4. Need auxiliary heat dissipation
If installed outdoors, the temperature of the LED display will sometimes be relatively high, and an air conditioner must be installed in order to achieve rapid heat dissipation, which is equivalent to an additional cost.
The main function of LED display
(1) Maximum brightness
In the industry "standard" discussed at the end of last year, there were no clear characteristic requirements for the important performance of "maximum brightness", which was in line with GB/T1.2-2002. In "Standardization Work Guidelines, Part 2: Methods for Determining the Content of Normative Technical Elements in Standards", "5.4.3 Values determined by suppliers", it is mentioned that "if the diversification of products is allowed, some characteristic values of the product may not be specified (although these characteristics have a significant impact on the performance of the product)".
Because the use environment of LED displays is very different, illuminance (that is, the average person calls ambient brightness) is not the same, so "for most complex products, as long as the standard specifies the corresponding test method, the supplier provides a list of performance data (product information) than the specific performance requirements given in the standard." These are in line with international standards, but this also leads to unrealistic comparisons in competitive bidding, which users do not understand, so that the "maximum brightness" required in many tenders is often much higher than actually needed.
Therefore, it is recommended that in order to guide users to correctly understand the performance index of the "maximum brightness" of the LED display, it is necessary for the industry to give a guide: in some occasions, in the use of different illuminance environments, what value can the brightness of the LED display meet the requirements.
(2) Primary color dominant wavelength error
Changing the primary color main wavelength error index from "primary color wavelength error" to "primary color main wavelength error" can better explain what characteristics this indicator reflects LED display. The dominant wavelength of color is equivalent to the hue of the color observed by the human eye, which is a psychological quantity and an attribute that distinguishes colors from each other. And the performance requirements specified by this industry standard, literally, users are unable to understand that it is an indicator that reflects the color uniformity of the LED display. So, is it to guide the user to understand the term first and then understand the indicator? Or first recognize and understand the LED display from the customer's point of view, and then give the user-understandable performance characteristics? As mentioned earlier, GB/T1.2-2002 (Standardization Work Guidelines Part 2 Methods for Determining the Content of Normative Technical Elements in Standards) one of the principles for product standard development is the "performance principle": "Whenever possible, requirements should be expressed by performance characteristics, not by design and description characteristics, and this method leaves the greatest room for technological development". "Primary color dominant wavelength error" is such a design requirement, if "color uniformity" is used instead, there is no LED that defines what wavelength.
For users, as long as you ensure that the color of the LED display is uniform, without considering what technical means you use to achieve it, leaving as much room for technological development as possible, which is greatly beneficial to the development of the industry.
(3) Duty cycle
As stated above, the "performance principle" "Whenever possible, requirements should be expressed by performance characteristics, rather than by design and description characteristics, an approach that leaves the greatest scope for technological development". We believe that "duty cycle" is purely a design technology requirement and should not be used as a performance indicator of LED display product standards; Everyone knows very well that there are users who care about the drive duty cycle of the display, they care about the effect of the display, not our technical implementation; Why should we create such technical barriers ourselves to limit the technological development of the industry?
(4) Refresh frequency
From the measurement method of the "Standard", it seems to ignore the real concerns of users, and it does not take into account the different driver ICs, driving circuits and methods used by various manufacturers, resulting in difficulties in testing. For example, the full-color screen bidding of Shenzhen Stadium, in the sample test of experts, the test of this indicator has brought many problems. The "refresh rate" frame shows the reciprocal of the time required, and the display is treated as a luminous light source, which is the flickering frequency of the light source. We can use an instrument similar to a "light frequency meter" to directly test the flicker frequency of the light source of the display screen to reflect this indicator. We have done this test, using an oscilloscope to measure the LED drive current waveform of any color to determine the "refresh rate", measuring 200HZ under white field; At the low gray level such as level 3 grayscale, the measured frequency is as high as a dozen KHZ, and measured with PR-650 spectrometer; WHETHER IN WHITE POINT, OR AT GRAYSCALE LEVELS SUCH AS 200, 100, 50, THE FLICKERING FREQUENCY OF THE MEASURED LIGHT SOURCE IS 200HZ.