As numbers of smart products continues to grow, an increasing variety of terminal products for different industries and usage environments have emerged into people's view, and the requirements for LCD displays have also gradually escalated, such as in industrial handheld terminals, walkie-talkie devices, instruments, and so on. Since these devices are often used outdoors, the relevant LCD displays are required to remain clearly visible under sunlight to facilitate accurate operations.

What Makes LCD Readable Under Sunlight?

For an LCD to be readable in the very bright outdoor environment, the brightness of the LCD screen needs to exceed the intensity of light reflected from the display surface. To be comfortably visible to the human eye, the brightness of the LCD should be at least 2.5 times that of its reflected light.

How to Achieve LCD Sunlight Readable?

It is approached from two aspects: increasing brightness or reducing reflection.

1. Increasing Backlight Brightness to Create High-Brightness Displays

• Advantages: Directly enhances screen brightness to ensure clear visibility in bright environments.
• Disadvantages: Increases power consumption, size, and cost, and may shorten backlight lifespan due to the higher current and denser LED arrangement required.
• Applications: Ideal for outdoor use, especially for devices that are not extremely sensitive to power consumption and cost, such as industrial handheld terminals and outdoor advertising boards.

2. Using Optical Bonding to Reduce Reflection

• Advantages: Improves contrast by reducing specular reflection, without significantly increasing backlight brightness, thus maintaining lower power consumption and cost.
• Disadvantages: Requires precise optical design and high-quality optical adhesives, increasing manufacturing complexity and cost. Additionally, it may have limited environmental adaptability, performing less optimally at extreme angles or in extreme weather conditions.
• Applications: Suitable for outdoor devices that require high contrast but do not want to excessively increase power consumption and cost, such as high-end walkie-talkies and professional instruments.

3. Using Transflective LCD

• Advantages: Can utilize ambient light as a light source, enhancing outdoor display brightness while reducing backlight usage and saving energy.
• Disadvantages: Displays less optimally indoors or in low-light environments. Additionally, the partially reflective mirror layer blocks some backlight, compromising indoor display performance. Transflective LCDs are also more expensive than fully transmissive LCDs.
• Applications: Ideal for devices that need good display performance both outdoors and indoors, with some tolerance for higher costs, such as portable navigation devices and outdoor adventure equipment.

4. Using Anti-Reflection (AR) and Anti-Glare (AG) Films or Circular Polarizers

• Advantages: AR films reduce reflection on the screen surface, improving visibility; AG films diffuse reflected light, reducing glare; circular polarizers further reduce reflection and enhance color performance. These methods are usually cost-effective and easy to implement.
• Disadvantages: May require periodic replacement or cleaning to maintain optimal performance, especially in heavily polluted outdoor environments.
• Applications: Widely applicable to various LCD screens requiring improved readability under sunlight, such as smartphones, tablets, and in-vehicle displays.

There are various methods to improve the readability of LCD screens under sunlight, each with its unique strengths and limitations. The most suitable approach depends on the specific use case and device requirements.