Many industrial applications require TFT displays with wider viewing angles to maintain image visibility from different viewing positions. Several technologies are available to improve TFT viewing angles, including MVA (Multi-domain Vertical Alignment), IPS (In-Plane Switching), and O Film technology.
For applications that require wider viewing angles than standard TN TFT displays, O Film provides a practical option when a suitable IPS panel is not available in the required display size or configuration. By applying an optical compensation film to a TN-based TFT structure, O Film can improve viewing angle performance while retaining display sizes and configurations that may not be readily available with IPS technology.
TN (Twisted Nematic) TFT-LCD panels are widely used in industrial display applications. However, one of the inherent characteristics of TN technology is gray scale inversion. When the display is viewed beyond a specified angle in the gray scale inversion direction, noticeable changes in gray levels, contrast, and color may occur, limiting the usable viewing angle from that direction.
WINSTAR O Film TFT displays are designed to improve these viewing characteristics while retaining the TN-based TFT structure. By adding an optical compensation film to the TN TFT panel, the usable viewing angle can be extended and the effects of gray scale inversion reduced. The comparison below shows the viewing performance of a standard TN TFT and an O Film TFT from different viewing directions.
The viewing angle of a TFT display is typically specified based on the contrast ratio (CR) measured from different viewing directions. The following tables compare the viewing angles of a standard TN TFT display and an O Film TFT display at CR ≥ 10.
| Item | Direction | Symbol | Condition | Min. | Typ. | Max. | Unit |
|---|---|---|---|---|---|---|---|
| Viewing Angle | Hor. | ΘR | CR ≥ 10 | 55 | 65 | - | Deg. |
| ΘL | 55 | 65 | - | ||||
| Ver. | ΦT | 45 | 55 | - | |||
| ΦB | 45 | 55 | - |
| Item | Direction | Symbol | Condition | Min. | Typ. | Max. | Unit |
|---|---|---|---|---|---|---|---|
| Viewing Angle (Gray Scale Inversion Direction) |
Hor. | ΘR | CR ≥ 10 | - | 75 | - | Deg. |
| ΘL | - | 75 | - | ||||
| Ver. | ΦT | - | 75 | - | |||
| ΦB | - | 75 | - |
In WINSTAR TFT specifications, view direction and gray scale inversion direction describe different characteristics. The view direction indicates the direction from which the display provides its preferred viewing performance. In contrast, the gray scale inversion direction is determined by the TFT LCD panel structure before the color filter and BEF (Brightness Enhancement Film) are added.
These two directions should therefore be distinguished when evaluating the viewing characteristics of a TFT display. The diagram below illustrates the view direction and gray scale inversion direction of an O Film TFT display.
Compared with a standard TN TFT display, O Film technology provides a wider and more balanced viewing range. In this comparison, the typical horizontal viewing angle increases from 65° to 75°, while the typical vertical viewing angle increases from 55° to 75°.
While O Film improves the viewing characteristics of a TN TFT display, adding the optical compensation film may reduce backlight brightness by approximately 15% to 20%. Therefore, both viewing angle performance and brightness requirements should be considered when selecting an O Film TFT display.
Different TFT technologies offer different viewing characteristics depending on the application requirements. To learn more about viewing direction, gray scale inversion, and the differences between TN, VA, and IPS technologies, read our Understanding TFT LCD Viewing Angle Technologies guide.
O Film TFT is a TN-based TFT display that uses an optical compensation film to improve viewing characteristics. It extends the usable viewing angle and helps reduce the effects of gray scale inversion while retaining the TN TFT structure.
O Film provides optical compensation for the TN TFT panel, helping maintain more consistent image visibility when the display is viewed from different angles. In the comparison shown in this article, the O Film TFT provides a typical viewing angle of 75° in both the horizontal and vertical directions at CR ≥ 10.
O Film improves the viewing characteristics of a TN-based TFT by adding an optical compensation film, while IPS uses a different liquid crystal alignment technology to achieve wide viewing angles. IPS generally provides wider and more consistent viewing performance, but suitable IPS panels may not be available in every display size or form factor. In such cases, O Film can be used to improve the viewing angle of a TN-based display while retaining the required display size or configuration.
WINSTAR offers standard O Film TFT displays in 2.8", 4.3", 5.7", and 7" sizes, as well as 3.9" and 5.2" bar-type O Film TFT displays. For available models and specifications, explore WINSTAR O Film TFT displays.
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