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Screen Usability

Screen Usability

What is the Technology to Optimize Sunlight Usability for Bright Environment?

Usability in bright environments is one of the critical characteristics of the display intended to use in an industrial environment. Many industrial LCDs are designed for outdoors or facilities with bright lighting. When choosing the best solution for your application, it is essential to dig into each possibility and then decide which one is the most suitable for your particular application. When choosing an LCD solution for your application, it is essential to consider the operating environment first. Based on the usage scenario, you can figure out which technology better suits your application. Winmate Inc. provides sunlight-readable display solutions for industries operating in challenging environments, including Defence and marine, oil and gas, manufacturing, healthcare. Winmate offers professional product customization service and project management to bring your unique ideas to life.

Technologies to Optimize Screen Usability

Manufacturers use various techniques to fine-tune the LCD screen for such demanding applications. Something the right combination of applied techniques is the key to success. Let's take a closer look at each method.

Main Factors Affecting Outdoor Readability

Have you ever thought about why you cannot see the display near the sunlight? We have listed some major factors that affect your display's readability and corresponding solutions to solve potential problem. One of the major problems in outdoor usage is the reflection of light that can be specular or diffuse depending on the nature of the interface. There are several panel enhancement methods that allow increasing screen usability in sunlight: transflective screen, apply dimming, use AR/ AG glass, light sensor or optical bonding.

Too dark
Glare / Mirror image
Color wash-out

The choice of sunlight readable solution depends on the lighting conditions of your industrial application. Please refer to the table below to check possible application and find the best LCD solution.

*Table 1. Lighting conditions and recommended LCD solution
Lighting Condition Ambient Brightness, nits Recommended LCD Screen Brightness, nits Application Recommended Solution Notes
Full dark environment 0 Up to 50 Marine bridge system Industrial LCD with wide dimming knob Turn display brightness to minimum or zero without flickering
Indoor without lighting > 500 200 Dark room Industrial LCD with brightness adjustment knob Easy to adjust to lower brightness
Indoor lighting > 1,000 Up to 300 PC desktop monitor, lab equipment Industrial LCD   Normal brightness and contrast ratio level
Bright shop lighting; Overcast skies, no shadows present 1,000 ~ 3,000 300 ~ 500 POS terminal, industrial display High brightness industrial LCD Industrial LCD with higher brightness and also high contrast ratio
Thin high overcast skies, indirect sunlight, shadows are visible 3,000 ~ 7,000 500 ~ 800 Shopping windows, public area like train station, airport Transflective LCD Transflective is the right choice for such conditions
Bright sunlight with blue sky 7,000 ~ 10,000 800 ~ 1,000 Outdoors kiosk, gas station High brightness industrial LCD For ultimate sunlight readable solution

Transflective LCD Technology

What is Transflective LCD Technology?

This method can be applied to certain selected regular TFT LCD. With the imposed reflective function, the modified LCD can reflect the ambient light passing the LCD cell and utilize the reflected light beams as its illumination. The stronger the ambient light is, the brighter the LCD will appear. As a result, the modified LCD is viewable under lighting conditions, including direct sunlight.

Table 1. The advantages of transflective LCD technology compare to other solutions
Technology Temperature of Standard LCD Panel Mechanical Modification Inverter Sunlight Readability
Increased brightness by lamp modification Heating issues Change LCD panel thickness Apply an inverter with higher current level Yes
Contrast enhancement No change No change No change Not available
Contrast enhancement No change No change No change Yes

Transflective LCD Technology Details

Transflective LCD modules hold both transmissive and reflective properties, and the method of image display depends upon the conditions of the ambient environment. The display uses a backlight with a transmissive property in dark environments, and external light with a reflective property in bright environments. Our improved transflective method allows for better color performance, which provides excellent color characteristics similar to the transmissive mode. The net reflectance rate of our transflective LCD solution varies from 0.9% to 1.3% based on the panel selected. For example, with 1.3% net reflectance rate and under 10,000 ambient sunlight conditions, the brightness gain is around 130 nits added to original backlight brightness.

Function Diagram of Transflective LCD Technology

The diagram below explains how transflective technology enhances the sunlight readable properties of the LCD screen.

Picture 1. Transflective LCD technology function diagram
Transflective LCD technology function diagram

Transflective LCD Operation & Storage Temperature Cautions

Keep the temperature at 0~50°C (32~121°F) and avoid direct sunlight on the LCD.
Although transflective LCDs are designed for outdoor environments exposed to sunlight, keeping the LCD at the proper temperature for operation (0~50°C,32~121°F)and storage is suggested to ensure stable performance.

Transflective LCD Operation & Storage Temperature Cautions

Arrange proper contrast ratio to ambient light

The contrast ratio is a critical factor that can influence readability. For example, if you put the LCD in a very high ambient light environment, even the display's brightness is pretty high; the contrast between the ambient and the display is too low. Therefore, you might not be able to see the clear LCD screen image. To be sunlight-readable, the contrast ratio to the ambient light need to be within a proper range

Arrange proper contrast ratio to ambient light

Use SAW/ IR Touch or Low Reflectance Rate Glass

If you demand a built-in protection glass, it is required to use the material with the reflectance rate less than 1%. Generally, the reflectance rate of protection glass can be as high as 4~6%, but we can provide the reflectance ration glass which is less 0.6% for better sunlight readability performance.

Arrange proper contrast ratio to ambient light
Case 1: Capacious Space

We add a thermal conductive dielectric sheet behind the LCD panel to improve the thermal issue. There are fans to exhaust the thermal current to keep the stable temperature inside of the mechanical housing.

Case 2: Airtight space

Suppose the LCD panel is set up in the customer's console or system, like a cabinet, to improve the thermal issue. In that case, it is necessary to use more fans or other thermal designs to exhaust the thermal current and have good ventilation to maintain a stable temperature inside.

Benefits of Transflective LCD Technology

  • Readable LCD under all lighting conditions, including direct sunlight
  • Enhanced contrast ratio for both indoor and outdoor conditions
  • Utmost indoor color saturation, brightness, and wide viewing angle
  • Full mechanical and electrical compliance with the existent system
  • Power saving and backlight life preserving in outdoor applications
  • No extra heat generation even when viewed at higher brightness

Applications of Transflective LCD Technology

Transflective LCD technology is suitable for all kinds of outdoor LCD applications such as video systems, kiosk, point-of-sale (POS), etc. Transflective LCD offers a most convenient and affordable solution for your various outdoor LCD applications.

Hyper Dimming

What is Hyper Dimming?

Under some specific user conditions, it may be required that the monitor be adjusted to a lower brightness level. The hyper dimming technology provides a broader brightness adjustment level and excellent appearance to meet the dim-to-black requirement. The high sensitivity of fully adjustable backlight control makes the product ideal for the day and night environment.

Hyper Dimming Technology Details

The hyper dimming technology applies the new PWM method to expand the dimming range higher than the previous generation of analog methods. The traditional methods for dimming enhancement are by adjusting the lamp current or by regulating the average current feeding the CCFL inverter. This dimming method is referred to as "analog dimming." This provides the highest efficiency circuits, limiting the dimming range or violating lamp specifications to achieve wide dimming ratios.

The "Pulse Width Modulation" (PWM) technology overcomes this problem, expanding the dimming range. We pulse the backlight at the full rated lamp current and modulate intensity by varying the time the lamp operates at the full rated current. PWM dimming can significantly extend the dimming range capabilities. PWM control of multiple lamps eliminates the typical problem of one lamp extinguishing before others at low intensities. Lamp layout and parasitic are no longer the limitations for display dimming capabilities.

With the user-friendly VR knob, it is possible to reach a truly dim-to-black state which allows for night vision operation. Combining the high-quality TFT LCD panel with a smoothly dimmable backlight offers crisp and excellent contrast images that fulfill most of the requirements of marine applications.

Function Diagram of Hyper DimmingTechnology

PWM controls the duty cycle from 0V to 5V or 0V to 3.3V for dimming ratio.

Diagram 1. Dimming ratio duty cycle.
Dimming ratio duty cycle.
Diagram 2. Lamp current waveform.
Lamp current waveform.
The lamp current waveform with the PWM circuit set at less than 100%

Benefits of Hyper Dimming Technology

  • The dimming range (duty cycle: 0%~100%) provides the most comprehensive brightness control ratio.
  • User-friendly dim-to-black VR knob adjustment for ease of operation.
  • Integration of sunlight readable displays and anti-glare coating ensures excellent readability for daytime and nighttime application.

Applications of Hyper Dimming Technology

  • Industrial and outdoor use
  • Marine navigation and ship automation
  • Aerospace and Defence applications

Anti-Reflective and Anti-Glare Coating Glass

What is Anti-Reflective and Anti-Glare Coating Glass?

The anti-reflective (AR) coating on the protection glass has excellent performance in tough ambient light conditions. With the normal glass, the strong reflection of the ambient light diminishes visibility and causes problems for viewer. Anti-reflective coated protection increases the contrast by enhancing light transmission rate over 95% and can effectively diminish the mirror images. The multi-layer vapor deposition coating either on one side or two sides of glass is designed to minimize reflectance and maximize transmittance. Another solution is an anti-glare (AG) coated protection glass, a microscopically rough surface laminated onto the topmost of display can diffuse glare. The chemically etched glass that has a slightly textured finish can reduce reflection by scattering light directed on its surface. It can soften the image of direct light sources visible in the reflection of the viewing area.

Anti-Reflective and Anti-Glare Coating Glass Technology Function Diagram

Anti-Reflective and Anti-Glare Coating Glass

Benefits of Anti-Reflective and Anti-Glare Coating Glass Technology

  • Protection glass with anti-reflective coating reduces reflection and maximizes transmittance.
  • Protection glass with anti-glare coating scatters light directed on the surface and softens the image of direct light sources visible in the reflection of the viewing area.

Applications of Anti-Reflective and Anti-Glare Coating Glass Technology

  • Exhibition signage
  • Outdoor kiosks
  • Public information stands
  • Point-of-sales (POS)

Light Sensor

How Light Sensor Work

The light sensor detects the illumination change outside, then sends the signal to MCU via the I2C interface. The MCU asks the inverter to switch the brightness if outside illumination changed. The MCU transmits pulse width modulation (PWM)signal to the inverter, and then the inverter changes the panel's brightness.

Diagram 1. Light sensor system diagram
Light sensor system diagram

Winmate standard light sensor design has five-step brightness settings: lightest, lighter, normal, dark, and darkest.Each step has its own illuminate range according different environment illumination. This technology makes the use of visual application more friendly and intelligently.

Table 1. Winmate five-step brightness settings
Setting LCD Panel Application Brightness
Lightest Outdoor or in bright sunlight 100%
Lighter Normal (Default) 75%
Normal (Default) Office and meeting room 50%
Dark Warehouse, storage 50%
Darkest Dark room without windows Minimum

Benefits of Light Sensor Technology

  • Better visual effect in a different environment
  • Intelligent brightness adjustment
  • Power saving

Applications of Light Sensor Technology

  • Public display
  • Outdoor kiosks
  • In-vehicle application