Source | Smart Car ClubKnowledge Circle | Entering the camera lens/module/CMOS chip group, plus micro yijijuechen2023With the development of autonomous driving technology and the acceleration of vehicle intelligence, there is an increasing amount of information that needs to be displayed in vehicles, leading to more and more screens. Looking at the new cars released today, large multi-screen displays in vehicles are an inevitable trend.SAIC Feifan R710.25-inch mini instrument screen, 15.05-inch OLED, 12.3-inch mini co-pilot screenAccording to the characteristics of these screens, they can be roughly divided into four types: LCD, OLED, Mini LED, and Micro LED. Among these four types, Mini LED has captured everyone’s attention in the past two years. This article will give you a brief introduction to these four display technologies.1. Backlight vs Direct DisplayA display image is composed of multiple pixels. The aforementioned technologies, LCD, OLED, Mini LED, and Micro LED, can be categorized based on their pixel illumination principles into two types: direct display and backlight. Each pixel directly emits light, known as direct display; while light produced by a light source is reflected to the human eye to form that pixel, this is referred to as backlight. Below, we will deepen this understanding through typical backlight and direct display solutions of Mini LED.1. What is Mini LED?First, let’s briefly review what Mini LED is. Mini LED, also known as “sub-millimeter light-emitting diode”, refers to LED devices with chip sizes between 50-200μm, falling between small-pitch LED and Micro LED, representing further refinement of small-pitch LED. Mini/Micro LED is a product of the fine development of LED displays, and as the technological path becomes clearer, it will become a new blue ocean for LED display applications.Huiwei Technology official website introduction about Mini LED backlit panelsCompared to the mainstream display technology LCD, Mini LED offers better display effects, with a significant increase in response speed, allowing for thinner and lighter screens, and greatly reducing power consumption, thus extending battery life.In comparison with OLED displays, Mini LED maintains excellent display effects and flexibility while having faster response speeds and higher high-temperature reliability. The important feature of Mini LED compared to small-pitch LED is its depackaging, primarily targeting the high-end small-pitch LED market, capable of achieving higher resolution and display effects.2. Distinguishing Backlight and Direct Display from Different Mini LED SolutionsUsing Mini LED for backlighting essentially remains LCD; direct display uses Mini LED to directly display graphics. The liquid crystal panel circuit controls the orientation of the liquid crystal molecules, allowing the backlight (different colors) to hit the display screen.Mini LED backlight (blue layer)Mini direct display is a combination of Mini RGB three-color chips, while Mini backlight consists of Mini blue light chips + QD, converted into white light, used in the backlight behind the liquid crystal.Tianneng’s Mini LED direct display screenIntroduction to Tianneng direct display screen:Based on LTPS glass substrate, using Mini-LED direct display technology, it can achieve high resolution, high reliability, and high contrast excellent display effects; at the same time, the AM driving scheme saves IC, has high circuit integration, and significant cost advantages.Using 6pcs of individual units, seamlessly spliced into an 18.1-inch product, with an LED pitch of less than 0.50mm, compared to traditional small-pitch displays, it can more easily enhance resolution; and the contrast far exceeds that of traditional LCD displays in the market, achieving a million-level.3. Comparison of Four Display TechnologiesCurrently, the aforementioned four display technologies each have their own advantages and disadvantages. Overall, the next generation of displays should theoretically be self-emissive, capable of flexible display shapes, evolving into Micro LED/OLED. However, due to some production issues with these two technologies, Mini LED backlighting has become a hot solution. Below is a simple comparative introduction to these four solutions.1. LCDThe composition structure of an LCD panel is relatively complex. In addition to the glass substrate, there are also liquid crystal layers, color filters, polarizers, light guide plates, and backlight modules, among other components. LCD refers to the liquid crystal layer within, which is used to control the direction of light; it does not emit light by itself and requires LED backlight as a light source. Additionally, LCD does not directly display images but needs to use color filters to create images. The color filter consists of many pixel points, and each pixel point contains red (R), green (G), and blue (B) sub-pixels. According to the basic concepts of color science, the three primary colors RGB can combine into various colors in reality based on different brightness ratios, and different colored pixel points combine to form the colorful images we see.The LCD backlight layer typically consists of dozens to hundreds of LED beads larger than 200μm. These LED beads are either fully on or fully off, and cannot be controlled individually. The entire screen shares a large backlight layer across all pixel points.Side profile of an LCD pixelLCD display panels are cost-effective, compact, lightweight, and energy-efficient, with overall mature technology and low failure rates.2. OLEDQLED (Quantum Light Emitting Diode) has unique optical properties, exhibiting different colors based on particle size when powered, with long lifespan, wide color gamut, high brightness, and pure colors.Compared to LCD, OLED screens have advantages such as displaying pure black, no light leakage, nearly infinite contrast, short response time, flexibility, low power consumption, and short response time; however, the disadvantages of OLED screens compared to LCD include shorter lifespan, screen flicker, and lower pixel density.3. Mini LEDMini LED miniaturizes the LED beads in the LCD backlight layer, with each LED bead measuring approximately 50-200μm. This allows for more backlight beads to be fitted into the layer, resulting in better brightness and uniformity. Mini LED divides the backlight layer into smaller sections, allowing for localized dimming through LED chips, thus improving the long-criticized black-and-white contrast issue of LCDs, achieving display effects close to OLED while avoiding lifespan issues.4. Micro LEDMicro LED integrates all the advantages of LCD and OLED, offering high image quality, low energy consumption, and long lifespan, but with high manufacturing complexity and cost.Side profile of a Micro LED pixel
