Sunlight readable TFT | Transflective TFT LCD vs High Brightness TFT

Sunlight readable tft lcd displays are including transflective tft lcd and high brightness tft lcd, both high brightness tft LCD (a kind of transmissive display) and transflective lcd are viewable under sunlight conditions, however, there are still many things are different for transmissive high brightness tft and transflective tft lcd. which one is better display for sunlight readability? let's see the comparison in this article, you would find the answer after reading this article.

What is transmissive TFT, transflective TFT LCD and high brightness TFT?

Transmissive tft lcd is the tft lcd panel in transmissive mode, tft panel is passive display, the display light has to rely on the backlight on the rear side of tft panel. the brightness of transmissive display is depended on the brightness of backlight and transmissive rate of tft panel.

Compare to transmissive display, transflective TFT has a reflector layer inside tft lcd cell, that is in front of the backlight. The incoming light is reflected and used to illuminate tft display. Transflective TFT have both "transmissive" and "reflective" modes. Both display modes work together for enhancing performance. In darker environments, the “transmissive” mode is dominant with emissions from the display’s backlight.

In daylight or bright environments, the “reflective” mode of the display is more dominant through reflectance from the internal mirror structure.

High brightness TFT LCD is a kind of transmissive display, the high brightness TFT panel is using common transmissive TFT technology, to compete high brightness sunlight, it use high brightness backlight technology for transmissive TFT panel.

Transflective TFT LCD displays screen become more and more popular because the demand of display working in daylight environments and direct sunlight, it is a good solution for daylight readable display.

Advantage of transflective screen:

The advantage of transflective display TFT modules is power savings compared to traditional “transmissive- only” displays.

Transflective lcd display combines the advantages of transmissive and reflective lcd displays, we also call it transflective screen,  the transflective screen are perfectly readable under almost any ambient light conditions. In addition, they are very energy efficient, making them ideal for battery powered devices and mobile applications.By using a transflective screen, we can save power by reducing or turning off the display’s backlight during bright environments because the “reflective” mode is dominant.

Transflective TFT become more popular since the demand of requiring good performance in bright environments and direct sunlight. so that the transflective TFT displays are perfectly readable under almost any ambient light conditions. In addition, they are very energy efficient, making them ideal for battery powered devices and mobile applications.

What is different between color transflective tft lcd and monochrome transflective lcd?

Beside the color filter in side tft panel, the main different of transflective TFT LCD and transflective monochrome lcd is the transflecitve layer location.

The transflective layer of monochrome transflective LCD is located on rear polarizer,

While the transflector of transflective TFT LCD is located inside the tft cell, the inside reflector is with higher efficient reflector and less light reflection to the display.

Reflective ratio about transflective TFT LCD:

If using transflective TFT LCD, the reflective rate is a key character for transflective TFT LCD. Higher transflective rate means better display performance in outdoor display, and it is better for power saving.

A true transflective TFT LCD, its reflective rate have to be up to 6%. As we know, the higher reflective ratio means lower power consumption, and better display performance for sunlight readable display.

In the market, there are some fake transflective TFT LCD that only with 2% reflective rate. the 2% reflective ratio is too low to say it is real transflective tft lcd display.  What it is main different between true transflective TFT and fake transflective TFT LCD. The secret is on the polarizer of LCD.

A fake transflective tft lcd modules are only using transflective polarizers on the backside of transmissive tft lcd, the way that make for tradition monochrome transflective LCD. It is no problem for a monochrome transflective LCD by using transflective polarizer, because monochrome LCD has higher transmittance ratio than TFT LCD panel. While a TFT LCD panel is with color filter, the color filter reduce the transmittance ratio of TFT panel, it lead to the reflective ratio is only 2% by using transflective polarizer.

What is a true transflective TFT LCD?

A true transflective TFT LCD, its transreflective layer is inside TFT LCD cell, its reflective ratio could be up to 6%~7% or more. while a fake transflective TFT LCD, it transflective layer is on the polarizer, because its reflective route is longer than the transflective layer inside TFT cell, so its reflective ratio is lower, its reflective ratio is only around 2%.  While 2% reflective ratio is too low for the reflective light under sunlight, it has to light on the high brightness backlight in the outdoor application. Therefore, the 2% transflective TFT lcd has no meaning for power consumption saving.

High brightness tft lcd vs transflective tft lcd:

Which is better sunlight readable tft display? In the following, we make comparisons about high brightness TFT LCD vs transflective TFT LCD display in technical parameters, display performance, and cost evaluation.

We take two Maclight products for the comparison:

1.  2.8” high brightness transmissive TFT LCD panel

2.  2.8” transflective TFT LCD

	Display mode	LCD Brightness	Transmissive rate	Reflective rate	LCD panel consumption	LCD backlight consumption	Backlight’s LED chips
2.8” high brightness transmissive TFT LCD	Transmissive	1000 nits	8%	0%	18mW	480mW	8 LED chips
2.8” transflective TFT LCD	Transflective	120 nits	1.8%	7%	18mW	480mW	8 LED chips

We could find the main differences for the two LCDs are on the transmissive rate and reflective rate of LCD. The transmissive LCD has high transmissive rate, while transflective LCD has high reflective ratio that up to 7%.

Display performance: Indoor vs Outdoor

The high brightness TFT LCD has higher transmissive rate, because high brightness TFT has high brightness backlight and high transmissive TFT panel, in indoor environment, the high brightness TFT has higher luminance compete to ambient brightness, therefore, high brightness TFT LCD has better display performance in indoor.

While for transflective TFT LCD, in indoor environment, the ambient light is lower, so LCD’s surface luminance is mainly from backlight. Because of transmittance rate of transflective TFT LCD is lower, so transflective LCD’s surface luminance is lower in indoor environment.

Therefore, in indoor environment, the high brightness TFT LCD has better display performance than transflective TFT LCD.

In outdoor environment, because the ambient light is strong, sunlight readable displays that work in directly sunlight, the display is required higher surface luminance to compete ambient light, under the stronger sunlight luminance, we would need the higher surface luminance of the sunlight readable display.

When transflective LCD technology used in regular TFT panel with a reflective function. by the imposed reflective layer, the modified tft 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 LCD is required.  Transflective LCD modules are with both transmissive and reflective properties, and the image display effect depends on the conditions of the ambient environment. For transflective tft lcd, the tft lcd display uses a backlight with a transmissive property in dark environments, and uses external light with a reflective property in bright environments.  so the transflective lcd method allows for better color performance than transmissive tft lcd with same backlight brightness, then the transflective lcd provides similar color characteristics similar to the transmissive mode that indoor.  The net Reflectance rate of regular Transflective LCD solution is from 1% to 7% varied from panels selected.  For example, with 2% net reflectance rate and under 10,000 ambient sunlight conditions, the brightness gain is around 200 nits added to original backlight brightness.

As Maclight display's working experience and research result, under directly sunlight in blue sky, the brightness of transmissive LCDs are required 800~1000 nits high brighness TFT LCD, after using the higher brightness TFT LCD with 800 nit or 1000 nits, we could get a good display quality and sufficient surface brightness to compete the ambient light in directly sunlight.

While for transflective TFT LCD, under directly sunlight, the stronger ambient light, the higher reflective luminance from transflective screen, the better display performance what we could get from directly sunlight.

So in outdoor environment, both 1000 nits high brightness TFT and transflective TFT LCD are suit for sunlight readable displays.

Display effect for different brightness and ambient condition:

Ambient Condition	Ambient  Brightness	Recommended LCD  Display Brightness
Dark environment	Less than 50 nits	Up to 50 nits
Indoor daylight	Less than 500 nits	Can be turn down to 200 nits
Indoor Lighting	Less than 1000 nits	Up to 300 nits
Overcast sky, without sky	1000 to 3000 nits	300 - 500 nits
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

Power consumption of High brightness tft lcd vs transflective tft lcd:

The power consumptions of high brightness TFT LCD and transflective TFT LCD are same if work indoor with backlight working. However, on outdoor application, we could reduce the brightness of backlight, or even power off the backlight of transflective TFT LCD,  only LCD panel is on working, because transflective LCD can reuse the light from ambient, then a transflective LCD’s power consumption is only   mA when working in outdoor. Therefore, The Tansflective TFT LCD is better on power saving for outdoor application, especially for the device powered by battery only.

So, Transflective TFT LCD is power saving than high brightness TFT LCD.

The cost of transflect tft lcd vs. high brightness tft lcd display:

The transflective TFT LCD is expensive than high brightness TFT LCD, its cost is double than high brightness, because transflective TFT LCD is rare, and inner transflect layer is much costly and complicate in TFT panel production.

In summary,

Transflective TFT LCD is fit to the device in outdoor, and for the device is sensitive for power saving, but transflective TFT LCD is more expensive than high brightness TFT.

High brightness TFT is also fit for outdoor application, but it is fit for the device that is not sensitive for power saving, and it is cheaper than transflective TFT LCD.

What Maclight can do for our customers:

If customers need sunlight readable displays solution for the applications, Maclight is able to provide both high brightness TFT Display and transflective tft display solutions. All our sunlight readable display TFT models are also available with resistive touch panel or capacitive touch panel solutons. Maclight's transmissive high brightness TFT LCD displays have the brightness up to 1000+ nits. Maclight transflective TFT LCDs also have high reflective rate with excellent sunlight readable performance and better power saving property, thay are perfect for outdoor daylight applications.

If you would like to know more about sunlight readable tft display, welcome to contact us at : [email protected].