Endless Conveyor Belt SHIJIAZHUANG VITURE IMPORT AND EXPORT TRADING CO.,LTD ,
4, grayscale
(3) Energy consumption and energy efficiency
With the extensive use of LED displays in various fields, more and more people are beginning to familiarize themselves with and use LED displays. How to judge the quality of display screens so as to select cost-effective products that suit them? This requires us to master Based on the basic technical indicators of LED display screens, it mainly identifies the quality level from the display screen's function and performance.
First of all, from the perspective of the functions of the display screen, the basic function of the display device is to display and display our various texts, pictures, videos, and other material to more people. The most important point is the actual display of the material. We need our display to have a very high degree of reduction, and how to improve its reducibility, mainly through the following technical indicators to complete.
1, brightness
The level of brightness gives a very intuitive feeling, one can distinguish the level, do not think that the higher the brightness of the display the better, mainly based on your use of the environment and viewing distance, indoor display is generally Appropriately around 1000nit, the display screen for outdoor use is higher than 6000nit, and semi-outdoor is suitable for between 2500 and 5000nit. The brightness of the screen with small pitch is required to be lower, about 100 to 300nit, in short, satisfying the audience Under the premise of seeing the image in the environment, long-term viewing of eyes will not produce a tingling sensation.
2, color temperature
When we see on the display screen the color of the image is inconsistent or different from the material, our picture is seriously distorted. This is related to the color temperature of the white balance of the display. If the human eye directly watches the display, it is white-balanced. The color temperature value is suitable between 6500 and 8000K. If the display screen used by the television station broadcasts, the actual color temperature of the screen body must be adjusted to about 5500K so that the screen on the display screen is true after being recorded and relayed by the camera.
3, perspective
For the display device, the larger the better the viewing angle, the greater the range of viewable. The viewing angle of the display is divided into a horizontal viewing angle and a vertical viewing angle. At present, the indoor full-color horizontal viewing angle can be greater than 140 degrees, and the vertical viewing angle is greater than 100 degrees, while the outdoor full-color screen has a horizontal viewing angle greater than 100 degrees and a vertical viewing angle greater than 90 degrees. Within the range of viewing angles, on the basis of clearly and completely viewing the images, there is no color cast at different viewing angles. This is mainly related to the RGB chip packaging arrangement of LED lamps. At present, there are two types of arrangement: product type and vertical type. the way.
When the level of the image on the display screen is poor and pixels are lost compared with the material, the gray level of the screen is low, and the contents of the material cannot be completely and clearly represented. Its professional test method is that the gray scale test can directly see the level of gray scale. At present, the industry can achieve the 16 BIT gray scale, and the follow-up will reach 18 BIT.
5, refresh rate
When the human eye directly looks at the display screen, it feels flickering on the screen. When many horizontal dark lines appear when shooting with a camera or a video camera, the refresh rate of the screen is low. Without affecting the direct viewing of the human eye, the refresh rate of the display screen cannot be less than 300 Hz. To meet the camera equipment such as cameras and video cameras, the refresh rate of the display screen should be over 2000 Hz.
6, contrast
When we watched the screen of the monitor, we felt that the screen was a little white, and the gray feeling was like a layer of tulle attached to the surface. The screen was not very transparent. This means that the contrast of the screen is low, and the contrast ratio cannot be low. At 1000:1, it is mainly related to the packaging of the LED lamp and the design of the module mask. The contrast of the LED lamp of the black bracket is obviously higher than that of the LED lamp of the white bracket.
7, uniformity
Whether the display screen is clean, there is no spotting, mosaic phenomenon, which is mainly related to the brightness and color consistency of the LED lamp, we can observe the brightness and color uniformity of the screen in RGB monochrome and white state. .
After we understand the functions of the display screen, a display screen with excellent display performance also needs to have good performance to be regarded as a high-quality display screen. We mainly identify the performance through the following aspects.
(1) Pixel out of control (in warranty period)
The pixels are out of control points and often bright points.
With the birth of small-pitch screens, their industry standards can no longer be applied to small gaps, and their standards should be higher. The rate of out-of-control should be controlled below 1X10-5.
(2), protection level and safety
The degree of protection is mainly waterproof and dustproof. The higher the IP value, the higher the protection level. The following figure shows the industry standard:
The safety is mainly reflected in the leakage current. The value of the leakage current is ≤3.5mA under the condition of U value X×1.1×; the second is the electrical strength, and the insulation breakdown is not observed under the test condition of 1,500V and 1min.
In order to reduce the power consumption of the display screen and improve the effective utilization of energy, thereby reducing the temperature of the display screen and prolonging its service life, the temperature drops by 10° C., and the product lifespan is doubled, mainly achieved in the following aspects:
A, low Vf value LED
B. Low Vds Constant Current Driver IC
C, low impedance PCB design
D, Module Operating Voltage 4.2V 3.8V
E. Switching power supply PFC ≥ 0.95 conversion efficiency ( ≥ 0.85)
(4) Reliability
A display even if its display effect is excellent, if its reliability is not high and the unstable failure rate is high, the quality of this display is also very low. In order to improve its reliability, it mainly considers the following aspects:
A. Material Selection: Material Analysis
B, thermal design: heat dissipation, heat distribution
C, redundancy: switching power supply, controller, PCB circuit
D, material tolerance: 20% balance
E. Reliability simulation verification test: life certification