Semi-transmissive LCD Viewing Angle Switching via Segmented Pixels
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Solution Overview
Problem
Current semi-transmissive liquid crystal display devices lack the ability to switch between a narrow viewing field mode for privacy and a wide viewing field mode, and they do not effectively manage grayscale inversion and viewing angle switching in reflective and transmissive displays.
Innovation Solution
A semi-transmissive liquid crystal display device with a liquid crystal panel having both reflective and transmissive portions, where each pixel has independent voltage control for the reflective and transmissive portions, allowing the device to switch between wide and narrow viewing field modes by adjusting luminance and viewing angle characteristics, enabling normal or dark display in each mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a semi-transmissive liquid crystal display device uses a single pixel structure for both reflective and transmissive display, then the device structure is simple, but the viewing angle cannot be switched between narrow and wide modes
Solution Approach 1:
Each pixel is divided into a reflective portion and a transmissive portion with separate electrode structures. The reflective portion has a reflecting electrode on the first substrate, while the transmissive portion has transparent electrodes on both substrates. This segmentation allows independent voltage control of each portion, enabling viewing angle switching between narrow (reflective mode) and wide (transmissive mode) by applying different voltages to different portions of the same pixel.
Solution Approach 2:
The liquid crystal display device achieves multi-functionality by enabling a single pixel to perform both reflective display and transmissive display modes. The pixel structure is designed to support both functions simultaneously through the coexistence of reflecting and transparent electrode portions, allowing the display to adapt to different viewing angle requirements without needing separate display modules.
2Manufacturing precision
If the liquid crystal thickness is made different in reflective and transmissive portions to optimize display quality, then the display quality is improved, but the manufacturing precision requirement increases
Solution Approach 1:
The patent applies local quality by creating different liquid crystal thicknesses in specific regions (reflective versus transmissive portions) of the pixel. The reflective portion has a smaller gap between electrodes optimized for reflective display, while the transmissive portion has a larger gap optimized for transmissive display. This localized differentiation of thickness allows each region to achieve optimal display quality for its intended function while maintaining a unified pixel structure.
3Adaptability or versatility
If independent voltage control is implemented for reflective and transmissive portions, then the viewing angle switching is enabled, but the device complexity increases
Solution Approach 1:
The electrode structure is segmented into reflective and transmissive portions with independent control capability. The reflecting electrode is positioned only in the reflective portion, while transparent electrodes are positioned in the transmissive portion. This segmentation enables independent voltage application to each portion, allowing the display to switch between narrow viewing angle (reflective mode with voltage applied to reflective portion) and wide viewing angle (transmissive mode with voltage applied to transmissive portion).
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables optimal display conditions by allowing the device to switch between wide and narrow viewing field modes, improving visibility and privacy by controlling the display content's visibility based on the viewing angle, and providing enhanced styling and privacy features.
Implementation Method 1
a liquid crystal panel having a liquid crystal layer between two substrates having electrodes formed thereon; a backlight for outputting light to the liquid crystal panel; and a controller for controlling a voltage applied to the liquid crystal layer
Implementation Method 2
each pixel of the liquid crystal panel has a reflective portion for reflecting light incident from a display screen side
Implementation Method 3
a transmissive portion for transmitting and displaying light that is output by the backlight
Data Source
AI summary
A liquid crystal display accommodates a reflective portion with a concavo-convex reflecting pixel electrode for reflecting incident light from the display face side, and a transmissive portion with a transmissive pixel electrode for transmitting light output from the backlight. In a wide viewing angle region, luminance of the reflective portion is greater than the transmissive portion. In other angle regions, luminance of the transmissive portion is greater than the reflective portion. In a wide viewing field mode, the reflective portion and transmissive portion both perform normal display. In the narrow viewing field mode, the transmissive portion performs normal display, while the reflective portion performs cancelling data display, thereby rendering unviewable the display content of the transmissive portion from beyond a certain viewing angle. Thus, a semi-transmissive liquid crystal display device and a portable terminal device is switchable between a narrow viewing field mode and a wide viewing field mode.