What are the advantages and disadvantages of LED display and DLP splicing screen?

Jul 02,2021| LED Knowledge

As TV programs become more colorful and interactive, the visual impact on the audience is also increasing, and the background of the program plays an important role.

In recent years, LED display screens and DLP splicing screens have gradually become the mainstream of the program background. The viewing effect and experience of the on-site audiences on the LED display screen is very intuitive. As long as the screen size and pixel pitch are appropriate for the viewing distance, this direct-viewing type The display screen can get excellent results.

However, the number of viewers in front of the TV is far greater than the number of on-site viewers. Therefore, the viewing effect of the viewers in front of the TV is the focus of research and discussion by TV technicians.

Many TVs have used LED display screens, but the effect of the TV picture is very different. Some have bright, clear and stable pictures from beginning to end; some are small and unclear in the long view, and are either the highlight of some activities or the close view. The erratic fringe interference, in some close-up shots of characters, often appears moire interference, disturbing the viewer's line of sight.

1. LED display

120 square meters P8 outdoor LED display big screen

 

LED is the abbreviation of LightEmittingDiode, which means light-emitting diode in Chinese. It is a solid-state semiconductor device that can directly convert electrical energy into light energy. LED display is an advanced digital information product. It successfully integrates computer technology, network communication technology, image processing technology, embedded control technology, etc. It has flexible display area and resolution (modularization can be assembled at will), high Brightness, low power consumption, long life, low heat, environmental protection and durability. It combines sound, light, electricity, graphics, and text. It is a terminal product that perfectly displays information in all directions.

LED display screens are used more and more in large-scale events in TV studios and TV broadcasts. As a stage background, it provides a variety of vivid and dazzling background pictures and more interactive functions, making the background pictures dynamic and static. , So that the performance and the background are integrated, making people feel immersive. It brings greater reverie space to the stage beauty, designs a modern and visually impactful stage, perfectly blends the atmosphere of the scene and the show, and realizes the functions and effects that other stage art equipment cannot achieve.

The viewing effect and experience of the audience on the LED display screen is very intuitive, as long as the screen size and pixel pitch and viewing distance are appropriate, this direct-viewing display screen can achieve excellent results. However, the number of viewers in front of the TV is far greater than the number of on-site viewers. Therefore, the viewing effect of the viewers in front of the TV is the focus of research and discussion by TV technicians.

Many TVs have used LED display screens, but the effect of the TV picture is very different. Some have bright, clear and stable pictures from beginning to end; some are small and unclear in the long view, and are either the highlight of some activities or the close view. The erratic fringe interference, in some close-up shots of characters, often appears moire interference, disturbing the viewer's line of sight.

Pay attention to the following aspects in the selection and use of the LED display:

1. Dot spacing should be as small as possible

The dot pitch is the distance between the center points of adjacent pixels of the LED display. The smaller the dot pitch, the more pixels per unit area, the higher the resolution, the closer the shooting distance can be, and of course the more expensive it is. At present, the dot pitch of LED display screens used in domestic TV studios is mostly 6-8 mm. In order to achieve excellent results, it is necessary to carefully study the relationship between the resolution of the signal source and the dot pitch, and strive to achieve consistent resolution. Achieve point-to-point display, so as to achieve good results.

2. The filling factor should be high

The fill factor (FillFactor) of the LED display is also known as the ratio of the light area, that is, the ratio of the light-emitting area of ​​each pixel to the physical surface area occupied by the pixel. LED display screens are arranged by discrete pixels, and there are obvious non-luminous black areas between the pixels. When viewed at close range, the picture is inconsistent and incomplete, and uneven brightness produces graininess. If the light source is confined to a small pixel surface area, so that the brightness of a single pixel is several times or even more than ten times the brightness of the entire screen. Cause more serious glare.

The TCO’99 standard recognized by the flat panel display industry stipulates that the fill factor should not be lower than 50%. At present, the fill factor of many LED displays on the market does not meet this indicator. The cut-off characteristic of the low-pass filter of the TV also directly affects the suitable shooting distance of the LED display with different fill factors.

The LED display with the same dot pitch has more attenuation than the larger filling factor, so the shooting distance needs to be increased. If the system low-pass filter passband is 4MHz and the high frequency attenuation characteristic is 12db/octave, then the shooting distance with a filling factor of 25% will be 1.15db more attenuated than that with a filling factor of 50%, and the shooting distance needs to be increased by about 10% .

The improvement of the fill factor makes the viewing angle of the display screen wider and the color mixing effect is more ideal, overcomes the glare problem of pixels, and also creates conditions for appropriately increasing the brightness of the entire screen to obtain better results.

Jiangsu Education Station has selected an LED display with a fill factor of 60%, which has moderate and soft brightness, uniform and bright colors, and clear and delicate expression, ensuring the high quality of the display.

3. The color temperature can be adjusted

Color Temperature (ColorTemperature) is the temperature determined by comparing the shape of the emission spectrum of the emitter with the shape of the fitted blackbody emission spectrum. When the studio uses the LED display screen as the background, its color temperature should be consistent with the color temperature of the light in the studio, so that accurate color reproduction can be obtained during shooting. According to the needs of the program, the studio lighting sometimes uses 3200K low color temperature lamps, sometimes 5600K high color temperature lamps, and the LED display needs to be adjusted to the corresponding color temperature to obtain satisfactory shooting results.

4. The shooting distance should be appropriate

As mentioned in the previous discussion about dot pitch and filling factor, LED displays with different dot pitch and different filling factor have different shooting distances. The proper distance between the person being photographed and the screen is 4-10 meters, so that you can get a better background picture when shooting people. If the person is too close to the screen, when shooting close-up shots, the background will appear grainy, and it is easy to produce moiré interference.

5. Ensure a good use environment

During the service life of the product, the failure rate is low only under suitable working conditions. As an integrated electronic product, the LED display is mainly composed of a control board equipped with electronic components, a switching power supply, and a light-emitting device. The life and stability of all these components are closely related to the operating temperature. If the actual working temperature exceeds the specified use range of the product, not only its life span will be shortened, but the product itself will also be severely damaged.

In addition, the threat of dust cannot be ignored. Working in a dusty environment, because the PCB absorbs dust, and the deposition of dust will affect the heat dissipation of the electronic components, which will cause the temperature of the components to rise, and then the thermal stability will decrease or even cause leakage, which will lead to burns in severe cases. Dust will also absorb moisture, which will corrode electronic circuits and cause short-circuit problems that are not easy to troubleshoot. Pay attention to keeping the studio clean. The renovation of the studio will generate a lot of dust, and the LED display needs to be protected in advance.

The use of LED display screens greatly enriches the display form of the program background. The LED display screen is used as a background, suitable for large-scale variety shows in large scenes and large studios.

As the large-screen splicing system is used more and more widely in various industries, it has greatly promoted the development of enterprises and the construction of informatization. As the best device for large-screen display, the LCD splicing screen has naturally attracted widespread attention. In fact, in the splicing screen market, there are not only LCD splicing screens, but also DLP splicing screens, LED splicing screens, and plasma splicing screens. Among them, the LCD splicing screen was put into the market later. Because it solves the various defects of traditional TV curtain wall, it can display the video information of each system conveniently, comprehensively and in real time, as well as the versatile large-screen function of split single-screen display or multi-screen display, so once it is launched, it has occupied entertainment , Security, transportation, energy, radio and television and other industries, have become the leader in the large-screen display industry.

2. DLP splicing screen

DLP splicing screen

DLP is the abbreviation of DigitalLightProcessing, which means digital light processing in Chinese. This technology first processes the image signal digitally, and then projects the light. From the technical principle of DLP, it has the advantages of less signal noise, accurate gray scale, higher reflectivity, seamless image display, and high reliability.

The DLP splicing screen is made up of multiple rear projection display units. Its main feature is that the seam is small and can be controlled to within 0.5 mm. Everyone calls it "seamless" splicing. This is also the result of the other two major technologies LCD and PDP. Unattainable. Because of its advantages, in recent years, TV stations have popularly used DLP splicing screens as the background of their studios. Well-known big TV stations such as CNN, BBC, SKY, and CCTV have achieved excellent program effects after using them.

DLP splicing screens also have disadvantages. Since the light source of DLP splicing comes from the bulb, it consumes a lot of power and heat dissipation, and the brightness will decrease after using for a period of time. The user must constantly replace the bulb to maintain the initial display effect. With the development of technology, thanks to the addition of LED light sources, the current DLP splicing screen has solved a series of problems such as frequent lamp replacement, high power consumption, and high heat dissipation. After adopting the LED light source, the DLP splicing screen has not only obtained a major breakthrough in service life and power consumption, but also has a revolutionary change in color, allowing the DLP splicing screen to continue to maintain its market advantage.

In order to achieve a satisfactory TV effect, we should pay attention to the following aspects in the selection and use of the DLP splicing screen:

1. The splicing gap should be as small as possible

We hope that the effect of the background display screen on the TV is seamless, which requires the stitching gap to be small enough so that the gap can not be seen from the lens. At present, the use of titanium alloy needle stitching technology can reduce the stitching gap to less than 0.2 mm, and at the same time, the design of the connecting plate can ensure that the screen does not deform during thermal expansion and contraction, providing the entire screen with high-quality image geometry and sharpness.

2. High uniformity

The DLP splicing screen is made up of multiple display screens, which causes the individual differences of each screen. We hope that they look like a large display with matching colors and brightness. This requires technical means to improve Uniformity. At present, this kind of technology is relatively mature, and advanced technology manufacturers have been able to operate in silent mode in the background without operator involvement. It integrates proprietary brightness and color sensors to continuously measure the color and brightness of the screen wall and between the projection modules. Communication, automatically match the brightness of all white, all black and all gray levels between the two and the color of all display modules, and keep the gray level of the entire display the same, thus achieving long-term consistency of images under multi-screen splicing.

3. The color temperature needs to be adjustable

Like the LED display, the color temperature of the DLP splicing screen needs to be consistent with the color temperature of the light in the studio to ensure the true reproduction of the image color.

4. The studio lighting should be well controlled

Compared with other display screens, the brightness of DLP splicing screen is relatively low, which requires the control of the studio lighting to avoid direct light on the screen. After groping and research, we used a cold light source lamp with a 20° grille, which effectively controlled the illuminance of the light on the screen within 100 lux, and ensured that the illuminance of the host’s face light could reach 800-1000 lux, which was satisfactory. Effect.

5. The light source needs to have high safety

The interactivity of live TV is getting stronger and stronger, and the security requirements for the background are getting higher and higher. The single screen size of the DLP splicing screen is larger. If there is a problem with the light source, it will cause a black screen, which is negative for this program or even a station. The impact will be great. Therefore, it is necessary to use dual-lamp hot backup or redundant LED modules as the light source.

6. Ensure good heat dissipation and control noise

Both UHP bulbs and LED light sources generate a lot of heat when they are working. Its heat dissipation is an important part of ensuring the life and normal operation of the light source. Advanced liquid cooling technology can make the cooling efficiency higher and the noise smaller, but also pay attention to keep it well. If the ambient temperature is low, the power cannot be cut off immediately when shutting down. Let the cooling system continue to run for a period of time, and then cut off the power after the light source is fully cooled. This will protect the light source and make it perform well when working.

DLP splicing screen is a major change in the background of the studio, but because of its high requirements for lighting, it is not suitable for use in large variety shows. It is suitable for news, interviews, live connections, weather forecasts, etc. in small and medium-sized studios. Type of show.

With the development of technology, there will be more new technologies and new ways to be applied to the studio background. We need to understand their characteristics in depth, and choose technical products as the background for different studio conditions, program formats and requirements, so that these new technologies can maximize their advantages to better serve programs and audiences.

After reading the above analysis and introduction, do you know anything about LED display and DLP splicing screen? If you want to know more about LED display, you can click the link below to view:

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  Article KeyWords:advantages of LED display ,advantages of DLP splicing screen

 

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