Positive & Negative Display and Viewing Direction of LCD Display
As we know, LCD screen is a negative display which can’t emit light on its own. It either relies on ambient light or uses LED backlight in the back as a light source. We divide LCD screen into transmissive LCD, reflective LCD, and transflective LCD according to the employing mode of light. Also, we divide LCD screen into the positive display and negative display according to the light of the background part.
|Item||Background||Graphic / Character||Application|
|positive display||on|| |
|reflective LCD / transflective LCD|
|negative display||off|| |
We can see the diagrams of Positive and Negative Display below.
View direction is the direction that we can clearly see the graphic in the LCD panel. We use the hours of the clock to name it, like 12:00 o’clock direction, 3:00 o’clock direction, 6:00 o’clock direction and 9:00 o’clock direction.
It is very simple, but most people can’t fully understand the meaning. We already introduced the difference between TN, HTN, STN and FSTN LCD in my previous post. The offset angle of liquid crystal in TN LCD is 90 degrees. What is that? If we see TN, HTN, STN and FSTN LCD in the perspective of view angle, it is much easier for us to understand.
TN LCD only has one view direction. Normally, it would be 6:00 o’clock direction or 12:00 o’clock direction. 6:00 o’clock direction means that we can see it clearly from the frontage and 6:00 o’clock direction. We can still see it clear from 3:00 or 9:00 o’clock direction if we make it well enough even it is 6:00 o’clock direction. The digital clock display in a car is installed on the right-hand side of the driver, which is usually 9:00 o’clock direction.
The view angle range of HTN LCD is a little better than TN LCD’s. For example: if the view direction of TN LCD is 6:00 o’clock direction, you will see the graphic very blurred at any angle of 3:00 o’clock or 9:00 o’clock direction. We can still see it clearly within 20 degrees of 3:00 o’clock or 9:00 o’clock direction if it is 6:00 o’clock direction HTN LCD.
Only when it comes to STN LCD, we can see it clearly in all the 4 directions. The view angle of FSTN LCD is much better than STN LCD’s, but it is much expensive, which is usually adopted by high-class electronic products, like laptop computers and cellphones.