The Secrets Behind Screens: Starting from Everyday Scenarios
Original SizeChange Image
In the morning, as you walk through the bustling streets, the huge outdoor advertising screens catch your eye with their vibrant colors and clear images, making the advertisement content immediately understandable. Whether showcasing the latest car models or promoting popular electronic products, they leave a lasting impression. Most of these large screens utilize LED technology, maintaining high brightness and contrast even under strong outdoor light.
After work, when you return home and lazily nestle into your sofa to watch popular dramas, the exciting plots and intricate visuals immerse you. The TV screen at this moment could be either LED or LCD; the different screen technologies provide varying visual experiences. LED TVs typically have thinner bodies and higher contrast, while LCD TVs, with their mature technology and relatively affordable prices, have won the favor of many consumers.
When you sit in front of your computer, processing work documents, engaging in graphic design, or playing an intense game, the display quality of your computer screen directly affects your work efficiency and gaming experience. For office workers, a screen that accurately presents text and graphs with high color fidelity is essential; for gamers and designers, high refresh rates, wide color gamuts, and fast response times are more critical. In the realm of computer screens, both LED and LCD have their strengths.
In these familiar life scenarios, have you ever wondered why, despite being screens, the display effects differ? The answer lies in the different technologies behind LED and LCD screens. Next, let us delve deeper into these two screen technologies, uncovering their mysteries and exploring how to choose the most suitable screen for different scenarios.
LED and LCD: Unveiling Definitions
Before we dive into the differences between LED and LCD screens, let’s clarify what they actually are. It’s like getting to know two people; you need to understand their basic information first.
LED stands for Light-Emitting Diode. As the name suggests, its core is a diode that emits light. In simple terms, it is a semiconductor device that can directly convert electrical energy into light energy. When current flows through it, electrons combine with holes, and the excess energy is released in the form of light, producing specific colors. Common examples include LED indicator lights, LED bulbs, and those colorful LED screens, all utilizing this principle. Many cities now use LED lighting for night scenes, which is not only energy-efficient but also bright and colorful.
LCD, on the other hand, stands for Liquid Crystal Display. It mainly consists of layers of liquid crystal, polarizers, light-transmitting glass, and substrates. Liquid crystals are a special substance that changes the arrangement of molecules under the influence of an electric field, thereby altering the polarization direction of light. LCD screens do not emit light by themselves; they require a backlight to illuminate the liquid crystal layer. When the light from the backlight passes through the liquid crystal layer, the liquid crystal molecules control the amount of light passing through by changing their arrangement, thus displaying different images and colors. It’s like an old-fashioned LCD TV, where the backlight acts like a spotlight illuminating the stage, while the liquid crystal layer is like the actors on stage, showcasing various exciting scenes through their movements (molecular arrangement changes).
Different Working Principles
When we explore the differences between LED and LCD screens, the first thing to understand is their working principles, akin to understanding two people’s personalities and working styles; only then can we truly grasp their differences.
(1) LED Screens: Self-Illuminating “Little Suns”
LED screens are like a group of disciplined and independent little suns, where each light-emitting diode is an individual that can emit light independently without relying on other light sources. In an LED screen, numerous tiny light-emitting diodes are closely arranged to form pixel points. These pixel points can quickly change their light-emitting state according to the input electrical signals through precise control circuits, thus presenting rich and colorful images and video content.
Take a common outdoor LED screen, for example; it can display various advertisements and promotional videos on a bustling commercial street. When an automobile advertisement is played, the light-emitting diodes on the screen will precisely control the brightness and color of each pixel point based on the car’s color and shape. The red parts of the car body will light up the corresponding red diodes and adjust to the appropriate brightness, while the black parts of the wheels will either not light up or emit very faint light, allowing for a clear and realistic representation of the car on the screen through such precise control.
(2) LCD Screens: The “Winding Journey” of Light
In contrast, the imaging process of LCD screens resembles a winding adventure of light. LCD screens do not emit light by themselves; they act more like light “managers,” primarily relying on the backlight to provide illumination. Early LCD screens mostly used cold cathode fluorescent lamps (CCFL) as backlight sources, while now they commonly use light-emitting diodes (LED) as backlight sources (this is what we refer to as LED-backlit LCD screens, which can easily be confused with true LED screens).
The light emitted by the backlight first passes through a polarizer, converting it into polarized light in a single direction. Next, the light enters the liquid crystal layer, where the liquid crystal molecules act like a group of well-trained little soldiers, aligning themselves at different angles under the influence of the electric field, thus controlling the amount of light that passes through. If we compare the liquid crystal molecules to windows that can adjust their opening angles, the electric field is the switch controlling the opening and closing of the windows. When the windows are fully open, a large amount of light can pass through; as the windows gradually close, the amount of light passing through decreases.
After passing through the liquid crystal layer, the light also goes through color filters. Color filters act like color magicians, separating and combining light according to the three primary colors: red, green, and blue, ultimately presenting the various vibrant colors we see on the screen. For example, when we see a beautiful landscape picture on an LCD computer screen, the light emitted by the backlight undergoes multiple “processes” through the polarizer, liquid crystal layer, and color filters. The liquid crystal molecules in different areas adjust the amount of light passing through based on the image information, and combined with the color filters’ separation of the three primary colors, vividly display the colors of the blue sky, white clouds, green trees, and red flowers in the landscape picture.
Comparing Display Effects
Having understood the working principles of LED and LCD screens, let’s look at the differences in their display effects, which are the most intuitive feelings we have when using screens, much like tasting food; you can tell how good it is with just one bite.
(1) Brightness and Contrast
LED screens are like a vibrant young man, excelling in brightness and contrast. Since each light-emitting diode can emit light independently, LED screens can easily achieve high brightness. Generally, the brightness of LED screens can reach 3500 – 5500 cd/m², allowing them to display images clearly even under direct sunlight. For instance, the outdoor LED advertising screens in bustling commercial streets remain colorful and clear under the bright sun, attracting the attention of passersby. Moreover, LED screens also have high contrast, clearly showcasing the brightest and darkest parts of the image, with deep blacks like the night sky and bright whites that are dazzling, enhancing the sense of depth and dimension in images. When watching movies, details in dark scenes can also be clearly presented, such as the mysterious creatures on Pandora in the movie “Avatar,” whose faint glow and the surrounding darkness are vividly displayed through LED screens.
In contrast, LCD screens are like a gentle and reserved gentleman. Since they rely on backlight to emit light, and the liquid crystal layer has certain limitations in controlling light, the brightness and contrast of LCD screens are relatively lower. The brightness of ordinary LCD screens typically ranges from 250 – 1500 cd/m², making it easy for screen content to be obscured by reflections in strong outdoor light, much like trying to view navigation on an LCD screen phone under the sun, where you often need to shield the sunlight with your hand to see it clearly. In terms of contrast, LCD screens struggle to achieve the deep blacks that LED screens can, often rendering black areas in a grayish tone, resulting in a slightly inferior sense of depth and dimension in images. When displaying night scene pictures, LCD screens may not effectively distinguish stars in the sky from the dark night, making the entire image appear flat.
(2) Color Performance
In terms of color performance, LED screens are like passionate artists, capable of showcasing extremely vibrant and vivid colors. This is due to their ability to directly control the light-emitting color and brightness of each pixel point, allowing for a wider color gamut. For example, LED screens can easily display the bright colors found in nature, such as the deep blue sky, lush green grass, and fiery red sunset, with high color saturation that provides a strong visual impact. For users who enjoy watching high-definition videos and playing large 3D games, LED screens can deliver a more realistic and stunning visual experience, making you feel as if you are in the scene. When playing Disney animated films, the rich and colorful visuals can be perfectly presented through LED screens, with every detail full of life and vitality.
LCD screens, on the other hand, are more like delicate and graceful painters, focusing on accurate color reproduction. They have a higher color fidelity, capable of accurately presenting the original colors of objects, resulting in detailed display effects. This makes LCD screens widely used in professional fields that require high color accuracy, such as graphic design and photo editing. Designers using LCD screens for their work can more accurately judge color combinations and details, ensuring that the colors in their designs match their expectations. However, due to the limitations of the backlight and color filtering technology, the color saturation of LCD screens is slightly lower than that of LED screens, and when displaying vibrant images, they may not provide the same strong visual impact as LED screens. When showcasing a brightly colored oil painting, while the LCD screen can accurately reproduce the colors of the painting, its vibrancy may not be as striking as that of an LED screen.
(3) Response Speed and Motion Blur
Response speed is like an athlete’s reaction time at the start, significantly impacting the display of dynamic images. LED screens excel in this area, with fast response speeds akin to sprinters, allowing for quick scene transitions. Generally, the response time of LED screens can reach a few milliseconds or even lower, enabling them to maintain smooth and clear displays during dynamic scenes, with almost no motion blur. When watching live sports events, the fast-running athletes and rapidly flying balls are clearly presented on LED screens, ensuring you don’t miss any exciting moments. During a football match, the players’ swift movements and passes are smoothly displayed on LED screens, with clean and crisp images, free from blurriness.
In contrast, LCD screens have relatively slower response speeds, resembling long-distance runners, and may exhibit motion blur during rapid scene transitions. This is because liquid crystal molecules require time to change their arrangement, causing the image update speed to lag behind rapidly changing visuals. Although technological advancements have significantly improved the response speed of LCD screens, in extreme cases, such as watching fast-paced action movies or playing high-speed shooting games, motion blur may still occur, affecting the viewing experience. In a tense first-person shooter game, when players quickly turn their view, the LCD screen may exhibit motion blur, causing the surrounding environment to appear unclear, impacting the player’s judgment and actions in the game.
Differences in Screen Characteristics
In addition to differences in display effects, LED and LCD screens also have distinct characteristics, akin to the lifestyle habits and behavioral traits of two individuals, which can influence our choices.
(1) Thickness
LED screens are like a slim fashion model, characterized by their lightweight and thin design. Since they do not require a traditional backlight layer, and each light-emitting diode can emit light independently, LED screens can be designed to be thinner. For instance, common LED phone screens can be made very thin, even allowing for narrower bezels and lighter body designs. Many flagship phones now use LED screens, keeping the overall thickness around 7 – 8 millimeters, making them feel very lightweight and portable for daily use. Moreover, in scenarios where thinness is crucial, such as tablets and laptops, LED screens are favored by users for their lightweight advantage. Thin laptop screens not only enhance portability but also improve overall aesthetics and quality.
In contrast, LCD screens resemble slightly bulkier athletes, as their working principle relies on backlighting, necessitating a backlight layer behind the liquid crystal layer, resulting in a relatively thicker overall design. Even with LED backlighting, while it reduces thickness to some extent, it still cannot compare to true LED screens. For example, some early LCD monitors could be several centimeters thick, appearing quite bulky. In today’s market, which emphasizes lightweight and portable electronic products, this disadvantage of LCD screens is quite evident, as thicker screens may pose inconveniences for users who frequently carry devices.
(2) Viewing Angles
Viewing angles are like the seating perspective when watching a stage performance; the wider the angle, the more comprehensive the content we can see. In this regard, both LED and LCD screens perform well, but LED screens have a slight edge.
LED screens are like an open circular stage, allowing clear viewing from various angles. Their viewing angles are very wide, generally reaching 170° – 180°, meaning that whether you view the screen from the front, side, or above, you can see clear and undistorted images and colors. For instance, during family gatherings, when everyone sits in front of the LED TV in the living room, even those sitting at the ends of the sofa can enjoy the same clear and vibrant images as those in the middle, without any color distortion or blurriness due to viewing angles. In public places, such as airports and train stations, LED displays allow passengers to clearly see the information on the screen from any direction, facilitating their travel.
LCD screens, however, resemble a stage that is slightly tilted; while most angles are still viewable, extreme angles may have some impact. LCD screens also have relatively wide viewing angles, typically around 160° – 170°, but in certain situations, when the viewing angle deviates too far from the center, the colors and brightness of the image may change, or even become blurry. For example, when sitting in a corner of a classroom watching an LCD projector screen at the front, if the angle is too extreme, you may find that the image on the screen appears dim and the text is not very clear, affecting the viewing experience.
Energy Consumption and Eye Protection Comparison
In our daily use of screens, energy consumption and eye protection are also significant concerns, acting like two silent assistants that influence our user experience—one relates to our electricity bills, while the other safeguards our eye health.
(1) Energy Consumption Comparison
In terms of energy consumption, LED screens are like savvy financial planners, exhibiting excellent energy-saving characteristics. Since each pixel point in an LED screen can emit light independently, when displaying dark images, those pixels that do not need to emit light can be turned off, significantly reducing energy consumption. For instance, when browsing a text-heavy webpage on an LED screen phone, the black background corresponds to pixels that consume almost no power, with only the text pixels emitting light, thus saving a considerable amount of energy. In applications that support dark mode, devices with LED screens can significantly reduce energy consumption when dark mode is enabled, meaning longer battery life and less frequent charging for users who frequently use mobile devices, which is very convenient.
In contrast, LCD screens are like a somewhat forgetful “little scatterbrain,” with relatively high energy consumption. Because LCD screens rely on backlighting to illuminate the entire screen, regardless of whether bright or dark images are displayed, the backlight remains operational, leading to energy waste. Even when displaying a completely black image, the backlight still emits some light, failing to achieve the true zero energy consumption of displaying black like LED screens. For example, when watching videos on an LCD screen tablet that contains many dark scenes, the energy consumption does not significantly decrease, resulting in shorter battery life and more frequent charging.
(2) Eye Protection Level
In terms of eye protection, LCD screens act like a caring little guardian, typically employing DC dimming technology. The principle of DC dimming is to change the screen brightness by increasing or decreasing circuit power, resulting in stable and continuous light emission without flickering. For users who spend long hours in front of screens, flicker-free screens can effectively reduce eye fatigue and discomfort, especially for those sensitive to flicker. For instance, many office workers need to stare at computer screens for extended periods, and using computers with LCD screens can make their eyes more comfortable during work, reducing the decline in work efficiency caused by eye fatigue.
LED screens, if using PWM dimming technology, may exhibit flickering issues at low brightness, which is not very eye-friendly. The principle of PWM dimming is to adjust brightness by controlling the frequency of the screen’s on-off alternation; at low brightness, the frequency of this alternation decreases, making flickering more noticeable. Although this flickering may be difficult to perceive with the naked eye, prolonged viewing of such screens can unconsciously affect the eyes, leading to fatigue, dryness, and discomfort, potentially harming vision. For example, many users of LED phone screens that use PWM dimming may feel eye discomfort when using them at low brightness at night, which is caused by flickering. However, with ongoing technological advancements, some LED screens now employ high-frequency PWM dimming or quasi-DC dimming technology, which improves flickering issues at low brightness to some extent, enhancing eye protection performance, but compared to LCD screens, the advantages in this area remain evident.
Cost and Lifespan Differences
When purchasing electronic devices related to screens, cost and lifespan are crucial factors we must consider, acting like the two sides of a balance that influence our final decision.
(1) Cost Comparison
LED screens are like a noble born into a prestigious family; due to their advanced technology and complex manufacturing processes, they require high-end materials and precision manufacturing equipment, resulting in relatively high manufacturing costs. For instance, a common LED TV of the same size and specifications often costs significantly more than an LCD TV. In the market, a mid-range 55-inch LED TV may cost around 4000 – 8000 yuan, while an LCD TV of the same size and configuration may range from 2500 – 5000 yuan. This is because each pixel point of an LED screen is composed of independent light-emitting diodes, and the production and manufacturing of these diodes require high-precision technology and equipment, thus increasing costs. Moreover, the research and development of LED screens demand higher technical and craftsmanship standards, which also contribute to the product price. However, as LED technology matures and market scales expand, the costs of LED screens are gradually decreasing, making them more accessible to consumers in the future.
In contrast, LCD screens are like a down-to-earth neighborly companion, with very mature technology and relatively simple production processes, resulting in lower manufacturing costs. Since the production of LCD screens has formed a relatively complete industrial chain, the costs at each stage have been effectively controlled, making devices with LCD screens more affordable in the market. In the computer monitor market, a 27-inch LCD monitor may cost around 1000 – 3000 yuan, while an LED monitor of the same specifications may be slightly more expensive. For price-sensitive consumers, devices with LCD screens are a good choice, as they can meet basic usage needs without imposing a significant financial burden.
(2) Lifespan Comparison
LED screens’ light-emitting diodes are like a group of tireless long-distance runners, boasting a long lifespan. Generally, the lifespan of LED diodes can exceed 100,000 hours; if used for 8 hours a day, an LED screen can last around 30 years, making it advantageous in scenarios requiring long-term stable operation. For example, outdoor LED billboards need to operate for long hours daily and withstand various harsh environmental conditions, and the longevity of LED screens ensures they maintain good display quality over years of use, reducing the costs and hassles associated with frequent screen replacements.
In contrast, the backlight source of LCD screens resembles a slightly weaker athlete, with a relatively shorter lifespan. The backlight source of ordinary LCD screens typically lasts around 50,000 hours, about half that of LED diodes. This is because the backlight source of LCD screens is affected by heat and aging over time, leading to a gradual decrease in brightness and display quality. When the brightness of the backlight source drops to a certain level, it needs to be replaced, which not only increases usage costs but may also affect the normal operation of the device. Additionally, as usage time increases, the liquid crystal layer of LCD screens may also experience aging, leading to a decline in color performance and contrast. On some older LCD monitors, we may notice that the screen colors have become dull and the image depth is not as good as before, which is a sign of liquid crystal layer aging.
Different Application Scenarios
The differences in characteristics between LED and LCD screens determine their strengths in various application scenarios, much like professional athletes excelling on their respective stages.
(1) LED Screens: The Dazzling Stars of Outdoor Displays
LED screens, with their high brightness, high contrast, wide color gamut, and long lifespan, have become leaders in outdoor display fields. In bustling commercial streets, large outdoor LED advertising screens are ubiquitous, captivating passersby with their vibrant colors and clear images, conveying various commercial messages for businesses, and becoming an indispensable part of the urban commercial atmosphere. In large sports events, LED displays play a crucial role, not only showcasing exciting moments of the game, displaying scores and player information but also presenting various advertisements and promotional content, enriching the viewing experience for spectators. For international large-scale sports events like the World Cup and the Olympics, the LED displays in venues are essential tools for information presentation and visual display, ensuring that global audiences can clearly see every detail of the game.
Moreover, LED screens are widely used in the lighting projects of urban landmark buildings. For instance, the night scene lighting show of Victoria Harbour in Hong Kong uses LED screens on skyscrapers to create a colorful light art world, attracting countless tourists and becoming a beautiful business card for the city. In large event venues, such as concerts and performances, LED screens serve as stage backgrounds, creating stunning visual effects that change colors and light effects in real-time with the rhythm and melody of the music, providing audiences with an immersive audio-visual feast.
(2) LCD Screens: The Practical Choice for Indoor Displays
LCD screens, with their mature technology, relatively low costs, good color fidelity, and flicker-free eye protection advantages, occupy an important position in indoor display fields. In households, LCD TVs are the choice for many consumers, meeting the daily viewing needs of families with stable display effects and moderate prices, making them great companions for home entertainment. In office settings, LCD monitors are also the standard for most office workers, providing clear and stable display effects for document processing, spreadsheet creation, and daily web browsing, and are less likely to cause eye fatigue during prolonged use, helping to improve work efficiency.
In professional fields that require high color accuracy, such as graphic design and photo editing, LCD screens are the preferred choice for professionals due to their excellent color reproduction capabilities. Designers need to accurately judge subtle differences in color and matching effects through screens, and LCD screens can faithfully present the original colors of images, allowing designers to express their creativity precisely. In hospitals, schools, and other places, LCD screens are also widely used in various display devices, such as medical equipment displays for showing patients’ physiological data and examination images, and electronic whiteboards in schools for teaching presentations, providing strong support for the normal operation of these venues with their stable and reliable performance.
How to Choose the Right Screen for You
Having understood the many differences between LED and LCD screens, you likely have a clearer idea when choosing a screen. So, how should you select the most suitable screen based on your needs? Here are some practical suggestions to help you make an informed decision.
(1) Pursuing Ultimate Display Quality
If you are a user with an extreme pursuit of display quality, such as a professional photographer, video editor, or an avid gamer and high-definition film enthusiast, then an LED screen is undoubtedly your best choice. Its high brightness, high contrast, wide color gamut, and fast response speed can provide you with a realistic and stunning visual experience. When processing high-definition images and videos, LED screens can accurately reproduce colors, making every detail come to life; when playing large 3D games, the fast response speed ensures smooth visuals, avoiding motion blur, giving you an edge in gaming; when watching high-definition movies, the deep blacks and bright whites, along with rich color layers, make you feel as if you have brought the cinema screen home, immersing you in the exciting plot.
(2) Focusing on Cost-Effectiveness
If you are a cost-conscious user with a limited budget and not particularly demanding display quality, then an LCD screen may be more suitable for you. Its mature technology and lower costs make devices with LCD screens relatively affordable. In meeting daily office, study, and entertainment needs, LCD screens can fully meet your requirements. You can purchase a larger LCD TV at a lower budget to meet the family’s needs for watching regular TV programs, or buy an LCD monitor for daily office work and web browsing, with stable display effects and moderate prices that will make you feel you got more than your money’s worth.
(3) Considering Eye Protection Needs
If you spend long hours in front of screens and are particularly concerned about eye health, then the flicker-free advantage of LCD screens becomes especially important. Their use of DC dimming technology allows the screen to maintain stable light emission at any brightness level, reducing eye fatigue and discomfort. This is particularly beneficial for those sensitive to flicker, such as children, the elderly, and those with eye conditions. If you need to stare at screens for extended periods, such as programmers and designers, using computers with LCD screens can make your eyes more comfortable throughout the workday, reducing the decline in work efficiency caused by eye fatigue. However, if you choose an LED screen, you can also pay attention to whether it employs high-frequency PWM dimming or quasi-DC dimming technology, as these technologies can also improve flicker issues at low brightness and enhance eye protection performance.
Conclusion: Future Outlook for Screen Technology
LED and LCD screens exhibit significant differences in working principles, display effects, screen characteristics, energy consumption, costs, and application scenarios. LED screens shine in outdoor displays and scenarios that demand ultimate visual experiences due to their high brightness, high contrast, wide color gamut, lightweight, and long lifespan; while LCD screens, with their mature technology, lower costs, good color fidelity, and eye protection advantages, hold a place in indoor displays and cost-sensitive fields.
As technology continues to advance, screen technology is also evolving. In the future, LED screens are expected to further reduce costs while continuously enhancing display performance, such as developing products with higher resolutions and finer display effects based on small-pitch LED technology, and achieving greater breakthroughs in intelligent control for more precise brightness and color adjustments. LCD screens will also not stagnate; they may delve deeper into quantum dot technology and other areas to further enhance color performance and contrast, narrowing the gap with LED screens in display effects.
At the same time, new screen technologies such as Micro LED and OLED are rapidly emerging, each with unique advantages, bringing more possibilities to the screen display field. Micro LED boasts higher brightness, faster response speeds, and longer lifespans, likely to occupy an important position in the future high-end display market; OLED, with its self-illuminating, ultra-thin, and flexible characteristics, has been widely applied in mobile phones, TVs, and is continuously expanding into new application scenarios.
In this rapidly evolving era of screen technology, we, as consumers, are undoubtedly the beneficiaries. Different screen technologies provide us with a rich array of choices, meeting our needs in various scenarios. I hope that after understanding the differences between LED and LCD screens, you can easily choose the most suitable screen device based on your actual needs. If you have any interesting experiences, unique feelings, or questions about screen technology during your screen usage, feel free to share in the comments section, and let’s discuss and explore the mysteries of the screen world together!