TFT Design Service

• Reflective polarizers are the best option for direct sunlight displays but are not ideal for low light conditions. Since a reflective polarizer reflects back 100% of the light it takes in, the brighter the surrounding environment, the easier it will be to read the display.

• Because they are only reflecting light and not creating it, these polarizers are best suited for monochrome displays. Reflective polarizers will increase display contrast and have the minimum amount of power consumption and heat creation.

ADVANTAGES OF REFLECTIVE LCD POLARIZERS

The brighter the ambient light (the light that is available from the sun, office lights, etc.) the sharper the contrast and the easier it is to read.

DISADVANTAGES OF REFLECTIVE LCD POLARIZERS

• A backlight will not illuminate the display since any light placed behind the polarizer will be blocked from passing through to the front piece of glass.

Note: It is possible to use a reflective polarizer with a side-lit LED Display, or edge-lit LED Display. 

• A side-lit display positions the LEDs above the reflective polarizer. This is a popular option since it provides a sharp contrast with the added benefit of being thinner (in the Z-axis) than an LCD with a backlight.

• With a transmissive polarizer, the display backlight must be on for the display to be readable. This type of polarizer does not reflect any light and so therefore, is not ideal for sunlight readability. However, the advantage of a transmissive polarizer over a transflective polarizer is that the backlight is significantly brighter.

•  This type of polarizer is ideal for consistent low light conditions.

ADVANTAGES OF TRANSMISSIVE LCD POLARIZERS

• The backlight behind a Transmissive polarizer will be brighter than the same backlight behind a Transflective polarizer, making the overall display brighter. 

• It is also possible to reduce the LED driving current with the goal of extending the half-life of the backlight.

DISADVANTAGES OF TRANSMISSIVE LCD POLARIZERS

The display can not be read when the backlight is off. Also, indirect sunlight the image can seem a bit ‘washed’, but E3 can add AR films to transmissive displays to limit the reflections outdoors.

• Transflective polarizers are a hybrid of reflective and transmissive. They use a combination of ambient light reflection and an internal backlight to create the display image. 

• A display with a transflective polarizer can be used with or without the backlight is on and can also be used in low or high ambient light conditions. Combining a transflective polarizer with E3 optical bonding and contrast enhancement film lamination will create a superior all-light readable display with extended battery life and reliability.

ADVANTAGES OF TRANSFLECTIVE LCD POLARIZERS

• A Transflective polarizer allows the display to be read with or without the backlight on. If the Liquid Crystal Display is located in an area with good ambient light, the backlight can be turned off and the display is still readable.

• When the LCD is moved into poor ambient light, the backlight can be turned on and the display can still be read.

• Most battery-powered products requiring a backlight integrate a Transflective polarizer. Another issue to take into account when selecting a polarizer is the half-life of its backlight.

DISADVANTAGES OF TRANSFLECTIVE LCD POLARIZERS

• A backlight placed behind a Transflective polarizer will allow some light to pass through, but the display will not be as bright as the same backlight placed behind a Transmissive polarizer. 

• If you need your backlight to be brighter and your display to operate in both strong and poor ambient light, there are additional methods to increase the brightness of the LED. Contact our US-based technical support for ideas.

• For applications requiring a larger user experience, wide viewing cone technologies can open viewing angles to as much as 89 degrees from the center without color or contrast shifts. Such displays are often stated to have symmetrical wide viewing cones.

• Display viewing cones, or viewing areas, are typically described as the maximum angle from the center for which an image is said to be viewable at an acceptable contrast ratio. Stated in degrees, displays with standard viewing cone specifications typically have 45-70 degree viewing angles in the left, right, up, and down directions from the center. Viewing such displays at angles greater than these specifications often results in image inversion, color changes, and/or darkening of the image.

• Conventional liquid crystal modes such as twisted nematic (TN) have problems such as brightness change and color shift depending on the viewing angle. In a TN LCD, the liquid crystal molecules stand up as voltage is applied to them. When liquid crystals are in an upright position, their visual characteristics vary significantly depending on the viewing angle. This results in variation in color and brightness from different viewing angles.

• With in-plane switching (IPS) mode, the liquid crystal molecules rotate in parallel with the panel. This means that the variation depending on the viewing angle is limited to showing any changes in visuals. Therefore, IPS LCD provides limited changes in brightness and color irrespective of the viewing angle to produce high image quality

• In extreme heat conditions, a display can turn dim or go to total black and if left in such conditions for extended periods, may cause permanent damage to the display. Fortunately, there are a number of solutions for applications requiring the use of a display in extreme environmental conditions.  Original LCD manufacturers offer displays with wider operating temperature ranges, as much as -40c to 85c thru the use of specialty liquid crystal and other key materials. Additionally, E3 Displays overcomes these challenges through the use of applied heating and cooling solutions.

• In high-temperature settings or without proper heat dissipation, glow marks or other visual defects can occur, therefore lowering the overall image and display quality. E3 Displays can add enhancements to wide temperature displays without the need for internal fans that are noisy and create unnecessary bulk. The right enhancements can help maintain proper airflow and can be designed with built-in temperature sensors from the manufacturer. This eliminates the need for internal fans, extends the LED half-life, decreases the overall power consumption of the display, and prevents visual defects.

• In cooler climates, the LCD fluid will slow down and change the response time of the display. We can install transparent heater films through an optical bonding process to maintain a sleek and modern display, as well as maintain display response time. The display heater will become active when the built-in sensor detects a pre-set ambient temperature. This will protect the display from becoming overheated and conserve display power. We also work with you to ensure your display is in a proper enclosure that will retain the heat generated to prevent battery drainage. E3 enhancements to wide temperature displays can operate in the most rugged environments, maintain battery life, and exceed aesthetic standards.