The Ultimate Guide for Sunlight Readable Display

When the displays are used in outdoor, have you struggled to read the instructions on the display under sunlight? We could see a display that looked good in the outdoor, but the display image wash out in outdoor environment with high ambient sunlight. So for outdoor environment, we need sunlight readable displays. In this article, we would introduce technologies of sunlight readable displays and some tips for improving sunlight readable displays.

1. What is sunlight readable display?

Sunlight readable displays means the display that could be readable under sunlight, they are designed to operate in an outdoor setting or in direct sunlight. These products are designed to be very rugged and durable materials to meet the most challenging environmental conditions. A good sunlight readable display has the properties of high contrast under directly sunlight without blur, wide temperature range, lower heat emission and power saving, long life time.

2. What is the best sunlight readable display:

OLED display is the best sunlight readable display in display quality.

But for different applications, we still have other choices, let's see:

• OLED Display:
1. OLED displays offer high contrast and excellent image quality in direct sunlight.
2. The cost of sunlight readable OLED screen is much expensive than lcd display,
3. The lifetime of common OLED displays are shorter than LCD displays.
• E-Paper Display: E-paper displays use a reflective technology that mimics the appearance of ink on paper.
1. E-paper displays are power saving displays,
2. but the reflesh time of E-paper display is much longer, it is only fit for the displays that no need to reflesh content frequently.
3. E-paper displays are also costly than lcd displays.
• LED Display: LED displays is often used for outdoor digital signage applications.
1. The LED displays use light emitting diode technology, it can be in higher brightness when in outdoor working.
2. Traditional LED screens are hard to be made in high resolution(PPI),and hard to get high display quality (beside micro-LED technology).
3. The power consumption of LED displays are much higher than sunlight readable lcd displays.

• Sunlight readable LCD display:

1. LCD displays are the most suitable technology using for sunlight readable displays, by using sunlight readable LCD displays, we can get the best balance in display effect of sunlight readable, power saving, high resolution, colorful, fast response time, temperature range, touch panel optional, and cost.
2. Display technologies comparison:

Feature	OLED Display	E-paper (E-ink)	LED Display	Sunlight Readable LCD
Resolution	High	Low to medium	Medium to high	Medium to high
Contrast Ratio	Extremely high	High	Medium	Medium to high
Lifestime	Short	Very long	Long	Medium
Brightness	Low to medium	Very low	Very high	High
Power Efficiency	Low	Very low	High	Medium
Sunlight Readability	Good	Excellent	Excellent	Good
Display Quality	Excellent	Fair	Medium	Good
Resolution (PPI)	high	low	very low	high
Best Use Cases	Indoor premium devices(phones, TVs)	Static content(e-books, signage)	Outdoor ads, stadiums	Automotive, industrial outdoor display

Conclusion:

Even OLED display is the best sunlight readable display in display quality, but for industrials outdoor application, after balance lifetime and display quality, Sunlight readable LCD displays is the best solution for industrial outdoor displays.

3. Technologies for sunlight readable LCD displays:

• High brightness LCD display:

1. High-brightness LCD displays use advanced backlighting technology on transmissive LCD panel, high brightness light compete the strong ambient's light in human's eyes visual system, make the LCD display content and image clearly viewable under sunlight.
2. High brightness transmissive TFT LCD displays is good choice for color display in outdoor, with high resolution, full colors, fast response time, economy.

• Reflective lcd:
1. Reflective lcd reflect ambient light on the lcd glass or polarizer, it is without backlight unit and power saving. the reflective light would increase the brightness of lcd screen and reduce the ambient light on the screen.
2. Reflective monochrome lcds are the economy solutions for sunlight readable displays, but it is only used for monochrome LCD technology.
3. For color tft display, due to the color filter inside tft panel,  the transmissive rate of TFT panel is much lower than monochrome LCD, the reflective light brightness is too low to use for reflective TFT. Therefore, reflective LCD technology is not used for Sunlight readable tft LCD displays.
4. Reflective LCD is only used for outdoor with strong ambient light, it can not use in dark environment indoor, because without backlight reflecting, we can not see the display content from reflective LCD in dark environment.
• transflective lcd display:
1. Transflecive LCD display combine the functions of transmissive LCD and reflective LCD displays. The backlight light could transmit through LCD glass, transflective LCD or its polarizer could resue the ambient light. When in dark environment, mainly use transmissive mode. When in outdoor with strong sunlight, mainly use transflective mode.
2. Transflective lcd displays have monochrome transflective LCD ( use transflective polarizer technology) and color transflective tft LCD (transflective TFT panel technology).
3. Transflective LCD is better for outdoor displays or handset display that require low power consumption.

Conclusion:

Both Transflective LCDs and high brightness LCDs are suitable for sunlight readable displays.

• Check more information about Transflective LCDs vs. high brightness LCDs =>：  （https://www.szmaclight.com/new/How-to-choose-Sunlight-readable-tft.html）

4.How to Make Sunlight Readable LCD Displays: Challenges, Principles & Solutions

  4.1 Challenges of sunlight readable displays: Overcoming Environmental Obstacles, displays face three major visibility challenges in bright outdoor environments:

• Glare and Reflections: Sunlight reflecting off the screen surface reduces effective contrast.(typically 2%-8% reflectivity,depend on the surface treatment) .The reflected light will superimpose with the light emitted by the display screen, reducing the effective contrast (that is, the difference in brightness between the displayed content and the background).
• Ambient Light Interference: Display brightness must compete with reflected light—if too low, content becomes washed out. The brightness of the display screen needs to be high enough so that the light it emits can overpower the reflection interference from the surrounding environment and form a recognizable image.
  If the display screen brightness is insufficient (for example, 100 nits), the reflected light (assuming 5% ambient light, i.e. 500 lux × 5% = 25 nits) may directly cover the displayed content, resulting in "inability to see clearly".
  
• Extreme Temperatures: High/low temperatures can impact brightness and response time

  4.2 How sunlight readable LCD display works: Principle

** Visibility depends on whether the display’s brightness and contrast surpass ambient light levels and human eye perception thresholds:

• Key Principle: Display luminance must significantly exceed reflected ambient light. That means an object’s brightness and contrast is higher than its ambient light, and the different ratio must be higher than human being eyes’ viewing threshold.
• Human Eye Perception (Weber-Fechner Law): The human eye's perception of brightness is not linear; instead, it follows an approximate rule similar to the Weber-Fechner Law - the logarithm of the perceived brightness change is proportional to the actual brightness change.
1. In bright light, the eye’s sensitivity threshold rises—requiring higher display brightness. When the intensity of ambient light is extremely high (such as when sunlight is directly shining), the human eye significantly increases the threshold for sensitivity to brightness (that is, a higher display brightness is required to be perceived as "visible")
2. In dim environments, the sensitivity threshold of the human eye decreases (a lower display brightness can be clearly perceived).

  4.3 Solutions for Sunlight Readability:

   4.3.1 Boost Screen Brightness

• High-Brightness displays: High brightness displays (exceeding 1000 nits) compete reflections from strong sunlight.
• Contrast decline is also related ambiend brightness and display brightness: High-brightness displays maintain contrast better under strong light.
1. The display ambient contrast is declined as the ambient illumination increased, they are inverse relationship.
2. The display with lower brightness, the contrast declined faster than higher brightness display.

   4.3.2 Minimize Ambient Light Reflection

• Anti-Reflective Coatings: Surface treatments (e.g., AG & AR glass) cut reflectivity.
• Polarization Filters: Block specific reflection angles by using circular polarizer.
• OCA bonding: OCA bonding for capacitive touch sunlight readable LCD displays

   4.3.3 Reuse ambient light for sunlight readable displays

• Transflective LCDs: Combine backlight with ambient light reflection for adaptability.
• Reflective LCD Displays: Rely entirely on ambient light, ideal for low power.

Therefore, we could use the Solutions for approaching Sunlight Readable LCD Displays,

1. Increase display's brightness -- High brightness display
2. Reuse the ambient light inside the screen -- Transflective LCD or reflective LCD
3. Reducing light reflectance on the surface of screen -- AG glass, AR surface treatment on the screen.
4. OCA bonding for sunlight readable touch screen. (if cost acceptable)

5. Factors we need to concern in designing sunlight readable lcd display:

• Brightness design: If it is transmissive display, choose the high brightness display refer to ambient illumination.

Ambient Condition	Ambient  Brightness	Recommended brightness for sunlight readable Display (Transmissive lcd)
Thin bright overcast sky, indirect sunlight, shadows are visible	3000 to 7000 nits	500 - 800 nits
Directly sunlight in blue sky, shadow are clearly	7,000 to 10,000 nits	800 - 1000 nits

• Raflective: For transflective display or reflective lcd, the higher reflective ratio would be benefit to sunlight readability.
• Power consumption: We have to consider power consumption for sunlight readable displays, especially for the devices with battery charge, such as hand held devices
• Temperature range: Choose wide temperature displays to stand outdoor environment and fast reponse LCD materials, the high brightness displays also intensify the temperature of sunlight readable displays.
• Life time: Choose the long life time sunlight displays for outdoor application. The LED backlight lifetime would be affected by long working in high brightness.

6. What Benefits from sunlight readable LCD displays:

There are many benefits for Sunlight-readable LCD displays in outdoor applications. Some of these benefits include:

• Good visibility under sunlight: Sunlight-readable LCD displays offer excellent visibility even in direct sunlight. This ensures that the LCD display is visible and readable even in bright outdoor conditions.
• Higher durability on outdoor: Sunlight-readable lcd displays are designed to withstand harsh outdoor environments. They are built with rugged materials and wide temperature range
• Energy Efficiency by using sunlight readable LCD technology: Sunlight-readable LCD displays use advanced backlighting or transflective technology to reduce power consumption. This makes them ideal for use in battery-powered outdoor applications.
• Cost-effective by using sunlight readable LCD: Sunlight-readable LCD displays are cost-effective compared to other outdoor display technologies. This makes them an ideal choice for businesses and organizations that require outdoor displays on a budget.

7. Maintenance of Sunlight Readable LCD Displays:

A good maintenance would lengthen the lifetime of sunlight readable LCD displays, so we suggest:

1. Put sunlight readable LCD displays into the devices with water proof case.
2. Add heat dissipation design for sunlight readable LCD displays if possible.
3. Add a shield for sunlight readable display, such as digital kiosk display in the outdoor.
4. Light off it when sunlight display is no need on working.
5. Keep the sunlight readable LCD display's brightness less than 80% maximum of its design value.
6. Add light sensor for sunlight readable lcd displays, the display brightness could be auto-adjusted following the ambient light.

8. Find a reliable Sunlight readable lcd displays supplier.

Maclight display is profession in sunlight readable displays, we could provide

1. High brightness TFT LCD panels up to 1500 nits,
2. Long lifetime and wide temperature sunlight readable LCD displays.
3. Transflective LCD solutions with low power.
4. Optional in resistive touch panel and capacitive touch screen, OCA bonding.
5. Sizes from 1.8 "~24"

Maclight sunlight readable LCD displays =>:

• 3.5 inch Sunlight readable TFT LCD displays:

• Transflective TFT LCD display
• 240*320 resolutions

• 3.5 inch high brightness TFT LCD displays:

• Brightness up to 1000 cd/m2