|The four main performance indicators of LED display advertising board|
Since 1998, the LED display industry has begun to work hard to organize the establishment of LED display industry standards, in order to correctly guide users to understand the performance indicators of LED display, standardizing the LED display rental market is very important. The following are the four major indicators of LED display.
No clear characteristic requirements are given for the important performance of "maximum brightness". Because the environment of the LED display is very different, the illumination (which is what the average person calls the ambient brightness) is different. Therefore, for most complex products, the supplier provides a performance data as long as the corresponding test method is specified in the standard. The (Product Information) list is better than the specific performance requirements given in the standard. These are in line with international standards, but this also creates unrealistic comparisons in bidding, and users do not understand this, resulting in the “maximum brightness” required in many bids is often much higher than the actual needs. Therefore, it is recommended that in order to guide users to correctly understand the "maximum brightness" of the LED display, it is necessary for the industry to give a guide: in some occasions, under the different illumination environment, what is the brightness of the LED display? Can meet the requirements.
2. Primary color dominant wavelength error
Changing the primary color wavelength error index from the "primary color wavelength error" to the "primary color primary wavelength error" is more indicative of what this LED reflects in the LED display. The dominant wavelength of color is equivalent to the hue of the color observed by the human eye. It is a psychological quantity and an attribute that distinguishes colors from each other. And the performance requirements stipulated by this industry standard, literally, users can not understand that it is an indicator reflecting the color uniformity of LED display. So, is it to guide the user to understand the term first, and then understand this indicator? Or do you first understand and understand the LED display from the customer's point of view, and then give you the easy-to-understand performance characteristics that users can understand?
One of the principles of product standard setting is the “performance principle”: “Whenever possible, the requirements should be expressed by performance characteristics, without design and description of the characteristics, this method leaves the greatest room for technological development”. The "primary wavelength error of the primary color" is such a design requirement, and instead of "color uniformity", there is no LED that defines the wavelength. For the user, as long as you ensure that the color of the LED display is uniform, and you do not have to consider what technical means you use to achieve, to leave as much room for technology development, this is greatly beneficial to the development of the industry.
3. Duty cycle
Just like the "performance principle" mentioned above, "if possible, the requirements should be expressed by performance characteristics, without design and description of the characteristics, this method leaves the greatest room for technological development." We believe that "duty cycle" is purely a design technology requirement and should not be used as a performance indicator for LED display product standards; everyone knows that there is a user who cares about the display duty cycle of the display, they care The effect of the display is not the realization of our technology; why should we create such technical barriers and limit the technological development of the industry?
4. Refresh frequency
From the point of view of measurement methods, it seems to ignore the problems that users really care about. It also does not take into account the driver ICs, drive circuits and methods used by various manufacturers, which makes the test difficult. For example, the full color screen bidding of the Shenzhen Stadium, in the expert sample test, the test of this indicator brings many problems. The "refresh frequency" frame shows the reciprocal of the required time, and the display screen is used as a light source, which is the blinking frequency of the light source. We can directly test the flashing frequency of the display's light source with an instrument similar to the “light-sensing 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", measured 200Hz in the white field; in the low gray level such as 3 gray scale, the measured frequency is up to More than ten k Hz, and measured with PR-650 spectrometer; whether in the white field, or in the gray level of 200, 100, 50, the measured source flashing frequency is 200 Hz.
The above points are only a simple description of the characteristics of several LED displays, and there are many "working life", "average time between failures" encountered in bidding, etc. No test method can be shorter. It is confirmed within the time that the LED display meets the requirements of 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. The industry should have a clear statement about this, which will be very beneficial to users, producers and the entire industry.
For how to guide users to correctly understand the product of a complex system such as LED display, it is necessary for the industry association to engage in more LED display technology forums. It is more practical to analyze this product from the user's point of view and guide users to correctly understand the LED display. .