Analysis of Four Major Technologies of Full-Color LED Display

Publisher: Supplier of LED Display Time: 2018-11-29 Views: 2635

1. Maximum brightness: In the industry "standard" discussed at the end of last year, there is no clear characteristic requirement for the important performance of "maximum brightness", which is in line with GB/T1.2-2002. It is mentioned in "5.4.3 Values determined by the supplier" of "Standardization Work Guidelines Part 2: Determination of the Content of Normative Technical Elements in Standards": "If product diversification is allowed, some of the products Property values need not be specified (although these properties have a significant effect on the performance of the product)."


Because the use environment of LED display screens is very different, the illuminance (that is, the ambient brightness that ordinary people call) is different, so "for most complex products, as long as the corresponding test methods are specified in the standard, the supplier shall provide a performance data. The list of (product information) is better than the specific performance requirements given in the standard”. These are all in line with international standards, but this also leads to unrealistic comparisons in bidding, and users do not understand this, so that the "maximum brightness" required in many bidding documents is often much higher than the actual need.



Therefore, it is suggested that in order to guide users to correctly understand the performance index of "maximum brightness" of the LED display, it is necessary for the industry to give a guide: in some occasions, in the use environment of different illumination, the brightness of the LED display depends on what value the brightness reaches. can meet the requirements.


2. Primary color dominant wavelength error: Change the primary color dominant wavelength error index from "primary color wavelength error" to "primary color dominant wavelength error", which can better explain what characteristics this indicator reflects on the LED display. The dominant wavelength of a 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. The performance requirements specified by this industry standard, literally, users cannot understand that it is an indicator that reflects the color uniformity of the LED display. Therefore, should we guide users to understand this term first, and then understand this indicator? Or should we first recognize and understand the LED display from the customer's point of view, and then give the user-friendly performance characteristics that are easy to understand? As mentioned earlier One of the principles for the formulation of product standards in GB/T1.2-2002 (Determination of the Content of Normative Technical Elements in Standards Part 2 of the Standardization Work Guidelines) is the "performance principle": "As far as possible, the requirements should be determined by performance. This method leaves the greatest leeway for technological development." "Primary color dominant wavelength error" is such a design requirement, if it is replaced by "color uniformity", it will not exist Define what wavelength of LEDs.


For users, as long as you ensure that the color of the LED display is uniform, you don't have to consider what technical means you use to achieve it, leaving as much room as possible for technological development, which is greatly beneficial to the development of the industry.


3. Duty cycle: Just like the "performance principle" mentioned above, "as long as possible, the requirements should be expressed by performance characteristics rather than design and description characteristics. This method leaves the greatest room for technological development". We believe that "duty cycle" is purely a requirement of design technology and should not be used as a performance indicator of LED display product standards; we all know that any user who cares about the driving duty cycle of the display screen, they care It is the effect of the display screen, not the realization of our technology; why should we create such technical barriers by ourselves to limit the technological development of the industry?


4. Refresh rate: 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 driving 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 brings many problems. "Refresh frequency" is the reciprocal of the time required to display a frame of the screen, and the display screen is regarded as a light source, that is, the flickering frequency of the light source. We can directly test the flickering frequency of the light source of the display screen with an instrument similar to a "photosensitive frequency meter" 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 frequency", and measured 200HZ under white field; at low gray levels such as 3-level gray, the measured frequency is as high as More than a dozen KHZ, and measured with PR-650 spectrometer; no matter in white field, or in gray level of 200, 100, 50, etc., the flicker frequency of the measured light source is 200HZ.


The above points are just a brief description of the characteristics of several LED displays. There are also many "working life", "mean time between failures", etc. encountered in bidding. There is no test method that can be used in a short time. Verify within time whether the LED display meets requirements for stability, reliability, or longevity; these requirements should not be specified. The producer can make a guarantee, but it cannot replace the requirement. It is a business concept, a contract concept, not a technical concept. Industry associations should have a clear statement on this, which will be very beneficial to users, producers and the entire industry.


As for how to guide users to correctly understand the product of such a complex system as LED display, it is still necessary for industry associations to hold more LED display technology forums, and to analyze this product from the perspective of users and guide users to correctly understand LED display.