LED Display Contrast Ratio

Sep 23, 2022 | knowledgebase | 0 comments

LED Display Contrast Ratio Definition

According to the definition of industry-standard SJ/T11281-2007 “Light Emitting Diode (LED) Display Test Method,”Contrast is a term that describes how bright or dark the image on an advertising LED screen is. It is calculated by comparing the brightness of the white and black colors on the screen. The contrast ratio is a number that shows how much brighter the white is than the black.

For example, an LED display contrast ratio of 1000:1 means that the white is 1000 times brighter than the black. The higher the contrast ratio, the more clear and colorful the image is. The lower the contrast ratio, the more dull and blurry the image is.

High coåntrast cob flip chip led wall
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Static and dynamic contrast ratio

: The contrast ratio can be measured in different ways, such as static contrast ratio and application contrast ratio. The static contrast ratio is measured in a completely dark room environment, and it is usually very high, as high as millions to one. The application contrast ratio is measured at an ambient illumination of 10±10% lx, and it is more realistic and practical. According to industry standards, an LED display application contrast ratio greater than or equal to 5000:1 is the highest level of C.

 Different Contrast ratios Among COB, GOB, SMD led displays

SMD LED Display: Black SMD LEDs VS White LED Screen.

Black SMD LED in small sizes, make them perfect for incorporation into instruments and devices. The smaller the chip size, the higher the contrast ratio of the LED display. This is because a smaller chip leaves more black space on the display, which reduces the brightness when the LED is off. Even though a smaller chip also reduces the brightness when the LED is on, the contrast ratio still increases significantly.

Black LEDs have a higher contrast ratio than white LEDs, which means they can produce darker blacks and more uniform colors. The contrast ratio of black LEDs is 8000:1, while the contrast ratio of white LEDs is 3000:1.

  • Power consumption: Black LEDs consume less power than white LEDs, which makes them more energy-efficient and eco-friendly. The power consumption of black LEDs is 350/m2, while the power consumption of white LEDs is 410/m2.
  • Brightness: White LEDs have a higher brightness than black LEDs, which means they can be more visible in bright environments. The brightness of white LEDs is Max. @2000cd/m2, while the brightness of black LEDs is Max. @1500cd/m2.
  • Display effect: Black LEDs can display black or gray colors more accurately and smoothly than white LEDs, which can cause distortion or noise in the same colors. Black LEDs have more stable and softer colors, although less bright than white LEDs.
high contrast black led with white led

Contrast Ratio: GOB LED Display VS SMD LED Display

High contrast GOB and black smd

LED Display Contrast Ratio: COB VS GOB

The contrast ratio of the COB led screen is higher than the SMD and GOB led screens. This is because the COB package does not use a bracket structure to support the chip device, which limits the size of the package body and the light-emitting pixel point. The COB package can use smaller chips according to different viewing needs, which increases the black area on the display and improves the contrast.

cob-led-display-visionpi-painting high contrast ratio copy
cob led display contrast ratio

LED Display contrast ratio Flip chip COB vs Lateral Chip COB 

The LED display contrast ratio of the flip-chip is higher than the front-mounted chip. This is because the flip-chip does not have electrodes and bonding wires on the light surface, which occupy part of the area that should be light. The flip-chip also has a larger light-emitting area and a higher luminous efficiency. This makes the LED brighter when it is on and darker when it is off, which enhances the contrast.

lateral chip cob vs flip chip cob

High Contrast COB LED Display

As aforementioned, the importance of high contrast for mini LED displays is obvious. The combination of full flip-chip and COB packaging technology of the mini LED display is an outstanding contribution to improving the contrast. Therefore, a full flip-chip COB display will be the best solution for a high-contrast ultra-fine-pitch LED display.

flip chip cob led display 0.9 1.25 1.56

With several years of experience as the leading mini LED display manufacturer in China, VISIONPI offers COB LED displays with high contrast, high brightness, high color, high definition, and other excellent performance. For instance, our COB series displays have achieved a contrast ratio of 15,000:1 while offering affordable prices. Therefore, our COB series mini LED displays can showcase unparalleled display effects to enrich users’ viewing experience. 

Pixel pitch covers P0.4-P1.8 to meet different requirements of users

  •  1,200nits brightness
  • 18Bit grayscale
  •  up to100,000:1 contrast ratio
  •  120% NTSC color gamut
  •  7,680Hz refresh rate
  •  Extremely high protection performance
  • Single Module Calibration Technology
  • onforms to industry standards and specifications
  • Self-developed optical display technology greatly protects the eyes
  • Multi-scene applicability

High Contrast Outdoor LED Display

The high contrast outdoor LED display designed to perform under direct sunlight incorporates features that optimize visibility and readability, even in challenging lighting conditions. Here’s a closer look at why black LED technology stands out and how it contributes to enhancing display performance in outdoor settings:

Outdoor Black LED Display Advantages

1. Higher Contrast Ratio: By using black LEDs, the display achieves a much darker black than traditional white or grey LEDs. This results in a significantly higher contrast ratio.

2. Sunlight Readability: Traditional LED displays can become washed out under direct sunlight due to their inability to produce true black colors, reducing their contrast.Black LEDs maintain their color integrity and contrast even in bright conditions. The deep blacks create a stark difference against the colored pixels, making the content more readable.

3. Lower Brightness Required:Traditional LEDs often require higher brightness levels to improve visibility in sunlight, consuming more energy.With black LEDs, the need for excessive brightness is reduced, lowering energy consumption while maintaining visibility.

high contrast outdoor led display black led

COB VS FLIP-CHIP COB LED Display

Jun 11, 2021 | knowledgebase, Technology | 1 comment

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In the field of LED display, with the development of upstream packaging technology, there gradually form two different LED display panel preparation technologies, SMD ;IMD; COB. We can use these two technologies to produce small-spacing mini LED display screens. And we will share some information about these two technologies with you.

What is COB?

COB (Chip on Board) is a kind of LED display packaging technology. LED light-emitting chips are directly bonded to the module board with high precision and connected to driver components on the module board through special media for overall protection of the light-emitting surface. COB packaging eliminates the two key procedures of turning LED chips into lamp beads and reflow soldering as compared to standard SMD packaging. 

 

Features Of COB LED DISPLAY

1. With Ultra-High Reliability

COB technology eliminates the process flow of SMD light-emitting tube packaging, color separation, taping, and patching, simplifies and improves the reliability of the product production process. Longer Life Span: Without the holder, the LED chip has lower heat resistance, largely increasing its life span

2. Smaller Pixel Pitch allowed

Smaller Pixel Pitch: the pitch of SMD is P1.2-P2.0, while COB is P 0.5-P2.0 .The COB technology  is not limited by the physical size, bracket, and lead of the SMD LED package, and can break through the SMD pitch limit, achieve higher pixel density, and have a more flexible dot pitch design.

3. Larger Viewing Angle: 

COB more likes the surface light source than the SMD, when light refracts, it has less light loss. COB Realizes The Conversion From “Point” Light Source To “Surface” Light Source.No pixel graininess; can effectively control the brightness of the pixel center, reduce the intensity of light radiation, inhibit moiré, glare, and glare to the retina, suitable for close and long-term viewing, not easy to cause visual fatigue, suitable for close-screen viewing.

4. Higher Protective Performance

The PCB circuit board, crystal particles, solder feet, and leads are fully sealed. The advantages of the sealed structure are an obvious-for examples, moisture resistance, anti-collision, prevention of pollution damage, and easier cleaning of the device surface.

Lateral Chip COB structure  VS A Flip-Chip COB structure

lateral chip cob vs flip chip cob

Flip chip cob led display advantages

1. Higher stability. Flip chip packaging technology eliminates wire bonding, eliminating the risk of gold wire breakage and simplifying the production process.

LED COB WIRE BONDING

2. Smaller pixel pitch.  Flip-Chip COB encapsulation is the chip-level integrated encapsulation. Without the wire bonding, the physical space size is only limited by the size of the light-emitting chip, which can achieve higher pixel density.

3. Better visual performance. Regarding display performance, the area of the Flip-Chip is smaller on the PCB board, and the duty cycle of the substrate is increased. It has a larger light-emitting area, which can present a darker black field, higher brightness, and higher contrast Presenting HDR-level display effects.

cob structrure visionpi

4. Cost-effective. There is no welding wire link, simplifying the production process and reducing equipment investment costs. As the industry scales, the product cost will be significantly reduced, especially when the dot pitch is less than 1.0mm.

Therefore, Flip-Chip COB technology is a necessary condition for the realization of MicroLED and will go further in the era of micro-display.

The Future Of direct view led display.

Flip-chip COB is an upgraded version of lateral COB, flip-chip COB improves reliability and visual performance, simplifies the production process, and narrows the pixel pitch. COB is the future of direct view led display 

COB LED Display

Jun 24, 2019 | knowledgebase, Technology | 0 comments

EVERY THING YOU NEED TO KNOW ABOUT COB LED DISPLAY

What is COB LED Display?

COB (Chip on Board) is a kind of LED display packaging technology. LED light-emitting chips are directly bonded to the module board with high precision and connected to driver components on the module board through special media for overall protection of the light-emitting surface. COB packaging  eliminates  the two key  procedures  of  turning LED chips  into lamp beads and reflow soldering as compared to standard SMD packaging. 
fip-chip cob
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COB LED CHIP DISPLAY VISIONPI
cob-led-display-waterproof anti-moisture

Flip chip COB LED Display

Chip-on-Board technology 

The bare IC is mounted directly on the substrate on the back of the PCB, then using a special method of welding using a pure gold wire, a bond is made between the base and silicon chip, then finally the COB is packaged together to form the full-color module.

Micro-led Mass Transfer Technology 

Mass transfer is a technique that can move Micro-LED chips from wafers to display panels.

This is the most challenging part of making MicroLED displays. There are three main challenges in this step “ accuracy, speed, and reliability.

High Accuracy

The transfer process requires high accuracy, as each microLED chip is minuscule and has to align precisely with its designated location. The tolerance for deviation is very low.

High Speed

The transfer process also requires high speed, as contemporary displays have very high resolutions. For instance, a 4K display comprises more than 24 million subpixels. To achieve cost-effectiveness and productivity, the transfer process has to handle multiple microLED chips simultaneously.

High Reliability

The transfer process also requires high reliability, as the display industry expects high standards and low defects. As the displays become larger and finer, the quality becomes more critical. We will elaborate on the microLED quality issue in a subsequent section.

Visionpi’s patented mass transfer technique is a novel approach for transferring millions of micro LED chips accurately. With the mass transfer technology, the UPH of micro & mini LED displays is more than 2.5KK, and the mass production yield rate is more than 99.999%.

Surface treatment technology

Surface treatment is to enhance color uniformity in the different application scenarios.

Flip Chip COB series micro &  mini LED display provides three types of surface treatments, including Brilliant Black, Natural Black, and Matte Black.

cob-led-display-visionpi-painting high contrast ratio copy

Flip chip cob led display production

Advantages of COB LED Display

This new and unique technology has a number of advantages over existing technologies such as SMD and DIP LEDs. Due to the small size of the LED chip, the COB system allows for a much higher packing density than SMD (SMT), the result being a more compact array giving better uniformity and higher intensity even at a close distance and greater heat dissipation for better stability, reliability, and lifespan.： COB chip and pin legs are sealed, resulting in better airtightness, higher resistance to external forces, and a smoother, seamless surface. COB has a much higher level of protection against moisture, electrostatic discharge (ESD), damages, and dust with surface protection rated IP65. COB is an integrated package with even light distribution, and the smooth surface makes images appear softer and friendlier to the human eye.

cob led display production process
  •  Stable technology process.  As shown above, SMD’s need to use reflow soldering. When the soldering paste reaches a temperature of 240°c the epoxy resin weight loss rate is 80% which easily causes the glue to separate from the LED cup, but in the case of COB technology there is not reflow soldering process so is more stable. Solder paste does not need to pass through ROHS approval
  • Finer Pixel Pitch. Pixel pitch is how close pixels are to each other on a display. COB LED technology makes pixel pitch smaller, which means more pixels and better resolution. Smaller pixel pitch also lets viewers see the display clearly even when they are close to it.
cob and smd led display
  • Better Light Effection Good heat dissipation / Low light attenuation, because the COB chip is directly dispensed onto the PCB, the area of heat dissipation is wider than SMD with better attenuation. The heat dissipation of the SMD is emitted through the bottom of its fixing.

cob led wall and smd led wall viewing angle
  •  Larger viewing angle COB small pitch technology has a much wider viewing angle and brightness both indoors and outdoors.
  • cob-led-display-viewing-brightness Superior Durability COB is better at withstanding collisions and the effects of Oil, Damp, Water, Dust, Oxidisation, and dust.

cob led display contrast ratio
  • High Contrast Ratio The contrast ratio of LED displays is an important parameter that determines how clear, vivid, and colorful the image is .COB can reach 15,000 to 20,000 static contrast ratio and up to 100,000 high dynamic contrast ratio.
cob led display ennergy saving
  • Superior Energy-saving COB LED technology delivers higher energy efficiency than SMD. This is important when it comes to the total cost of operation for large format displays that are going to be used all day, every day for months and years to come.

Disadvantages of COB LED Display

  • Difficulty in manufacturing finished products

When an LED display is encapsulated in COB, it must be ensured that the lamp is free of defects before refilling. Unlike an SMD package, a single bulb cannot be replaced, so the packaging process is very demanding. (Visionpi’s patented mass transfer technique is a novel approach for transferring millions of micro LED chips accurately. With the mass transfer technology, the UPH of micro & mini LED displays is more than 2.5KK, and the mass production yield rate is more than 99.999%.)

  • Maintenance inconvenience

if it is a traditional SMD package, you can disassemble the unit board after a single LED soldering repair. However, when it comes to the COB product, maintenance will affect the surrounding lamps, making it very difficult. Although its protection performance is better, we have to admit that there will still be a certain dead light rate. In this case, the only option is to replace the unit board. generally speacking the cost of maintenance is bout the same with SMD.COB panel is more expensive but with much less possibility of failures. as the cob manufacturing cost is decreasing, now the cob led display’price is very clost to SMD’s, in the future the cost will be lower than SMD.

Lateral Chip COB VS A Flip-Chip COB

LC-COB and FC-COB are two types of LED packaging technologies used in Chip-on-Board displays.

LC-COB (wire bonding) has LED chips mounted in parallel on the substrate with electrical connections made from the side of the chip. The chip is attached to the board with an adhesive. Each pad on the device is connected with a fine wire lead that is welded to the pad and to the circuit board. the wire lead would limit the development of finer pixel pitch led display. 

FC-COB, on the other hand, has LED chips mounted upside down on the substrate with electrical contacts facing downwards. flip chip COB eliminates wire bonding and simplifies the production process.

  • Better Thermal performance.

Conductive adhesive bonds the chips to the substrate for better thermal and electrical performance.

  • Higher brightness

A reflective layer on the substrate directs light emitted from the LED chips toward the front of the display, providing high brightness.

  • better visual performance

The flip chip takes a smaller space on the PCB board, providing a larger light-emitting area. The substrate presents a darker black field and higher contrast

flip-chip cob vs lateral chip cob led display

Flip-chip COB is the future.  Compared with the SMD; GOB Packing technology (GOB VS COB), COB  is the next-generation technology advance in COB that improves display quality and durability. It makes the pixels closer, brighter, and more visible from different angles and distances. It also makes the display more reliable, energy-efficient, and resistant to dust, moisture, and collision.COB LED displays are still a popular choice for a wide range of applications such as indoor and outdoor advertising displays, stage backdrops, and event screens, due to their high-quality visuals, energy efficiency, and durability.. In short, COB LED screen technology is a future development trend,the cost will be decreased with the mass transfter technology’s development.

Why Choose Visionpi’s COB LED DISPLAY?

We are a reliable display supplier that offers Mini COB LED displays with three advantages:

  • Technology Innovation: We use COB full flip-chip packaging technology and our patented Mass Transfer Technology to improve the performance and yield of small-pitch LED displays.
  • Excellent Performance: Our Mini COB LED displays have no light stringing, sharp image, vivid color, good heat dissipation, long life, high contrast ratio, wide color gamut, high brightness, and high refresh rate.
  • Cost-effective: Our Mini COB LED displays are energy-saving, easy to install, less maintenance, low maintenance cost, and very cost-effective.
  • Competitive Price.  As a pioneer and leading OEM COB-led panel, we made big progress in mass transfer technology to decrease the cost of cob-led display to the same level price as SMD led display.

Visionpi Flip chip COB series 

Pixel pitch covers P0.4-P1.8 to meet different requirements of users

  •  1,200nits brightness
  •  18Bit grayscale
  •  up to100,000:1 contrast ratio
  •  HDR 10 supported
  •  120% NTSC color gamut
  •  7,680Hz refresh rate
  •  Extremely high protection performance
  • Single Module Calibration Technology
  • onforms to industry standards and specifications
  • Self-developed optical display technology greatly protects the eyes
  • Multi-scene applicability

Outdoor COB LED Display

Pixel pitch covers P0.4-P1.8 to meet different requirements of users

  •  3500 nits brightness
  •  16 Bit grayscale
  •  up to 10000:1 contrast ratio
  •  HDR 10 supported
  •  120% NTSC color gamut
  •  38400Hz refresh rate
  •  Extremely high protection performance
  • Single Module Calibration Technology
  • onforms to industry standards and specifications
  • Self-developed optical display technology greatly protects the eyes
  • Super wide viewing angle 170

Flexible COB LED Display

COB flexible LED modules merge the compact, high-intensity lighting benefits of Chip On Board (COB) technology with the adaptable, bendable nature of flexible LED modules. This innovative combination allows for the creation of highly durable, uniformly lit, and versatile lighting solutions that can be tailored to fit curved and irregular surfaces without compromising on light quality or intensity.

COB LED Display Modules

Explore VisionPi’s COB LED Display Module, the pinnacle of cutting-edge technology for OEM applications. As a leading manufacturer, VisionPi offers robust, high-density COB (Chip On Board) LED displays, perfect for creating seamless, high-resolution screens with exceptional durability and performance. Ideal for a wide range of applications from digital signage to sophisticated video walls, discover how our COB LED modules can transform your visual presentations into captivating experiences. Dive into the future of displays with VisionPi’s reliable and innovative solutions

cob led display modules 1.25 1.56 0.9

COB LED VS Mini LED

Mar 25, 2019 | General | 0 comments

The packaging technology of LED display modules can be divided into two types, one is SMD (Surface Mounted Devices) and the other one is COB (Chip On Board).  4in1 LED is still a number of SMD. The comparisons of these two products are as follows:
I. Production Cost: As compared to the flip-chip COB module, the 4in1 LED module has more production workstations (as shown in the picture below), which increases production cost. In addition, the flip-chip COB module adopts the mass transfer method to set LEDs on PCB boards; however, the 4in1 LED module applies the traditional single-chip per transfer method to set LEDs on PCB board one-by-one. Thus, the production capacity is ten to hundred times different. The cost advantage of flip-chip COB module may help speeding up the construction and expansion of virtual production environments.

As compared to the flip-chip COB module, the 4in1 LED module has more production workstations

  • II. Display Performance: In terms of display performance, the area of the Flip-Chip is smaller on the PCB board, and the duty cycle of the substrate is increased. It has a larger light-emitting area, which can present a darker black field, higher brightness, and higher contrast.COB LEDs are precisely placed on PCB boards so that the flatness and accuracy of the module are outstanding. Moreover, the viewing angle of the flip-chip COB module is around 175°, which is wider than the 160° viewing angle of the 4in1 LED module, and there is no pixel granularity on the flip-chip COB module. In addition, the flip-chip COB module can effectively suppress the moiré effect.

 

  • III. Product Reliability:  Flip-Chip COB can achieve true chip-level spacing, reaching the level of Micro LED. This is because, from the perspective of the LED chip, the Flip-Chip does not require wire bonding, which breaks the pixel pitch limit of the formal chip and solves the problem of metal migration in the formal LED.

    LED surface of the flip-chip COB module is packaged with an integral epoxy resin mold to avoid oxidation; the exposed solder joints of the 4in1 LED module are susceptible to interference by water and oxygen.

  • Please refer to the following comparison table of product reliability. Comparing the various characteristics, the overall reliability of the flip-chip COB module is much better. It is more suitable for the film and TV industry that requires frequent disassembly and assembly of LED modules.
flip chip cob vs mini 4 in 1 led

In summary, from the perspective of production cost, display performance and product reliability, the flip-chip COB module is significantly better than the 4in1 LED module. As an upgraded product of formal COB, flip-chip COB is based on the advantages of formal COB ultra-small dot pitch, high reliability, and non-glaring surface light source. Further, improve the reliability, simplify the production process, better display effect, perfect near-screen experience, and real chip-level spacing can be realized.

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