Display Panel Common Voltage Switching for Anti-Peep Security
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Solution Overview
Problem
Conventional display apparatuses with wide viewing angles pose a risk of confidential information leakage, as they can be easily viewed by onlookers, necessitating an anti-peep feature to prevent unauthorized access.
Innovation Solution
A display apparatus with a display panel and a common voltage setting circuit that alternates between normal and complementary voltage levels on common electrode lines during different frame periods, ensuring that viewers off-axis see only a grayscale or single-grayscale screen, thereby preventing normal viewing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a wide viewing angle display is used, then the display can be viewed by multiple viewers, but confidential information becomes vulnerable to onlookers
Solution Approach 1:
The patent applies periodic action by alternating the common electrode voltage between normal and complementary levels at different frame periods. During the first frame period, normal common voltage is applied, and during the second frame period, complementary common voltage is applied. This periodic voltage switching causes the liquid crystal molecules to change orientation, making the display appear normal to front viewers while appearing as grayscale or inverted images to side viewers, thus preventing information leakage while maintaining wide viewing angle capability
Solution Approach 2:
The patent changes the voltage parameter of the common electrode between two states: normal voltage level and complementary voltage level. By switching the common voltage parameter between these two states at different frame periods, the display achieves different viewing characteristics. Front viewers see normal images while side viewers see grayscale or inverted images, resolving the contradiction between wide viewing angle and information security
2Object-affected harmful factors
If anti-peep function is implemented by switching common voltage levels, then information security is improved, but the display requires additional voltage control circuitry
Solution Approach 1:
The common electrode voltage switching mechanism serves multiple functions: it maintains normal display operation during first frame periods and enables anti-peep function during second frame periods. The same common electrode lines and voltage control circuitry are used for both normal display and security functions, eliminating the need for separate dedicated anti-peep hardware and reducing overall device complexity
Solution Approach 2:
By implementing anti-peep function through periodic voltage switching rather than continuous complex control, the system achieves security with relatively simple circuitry. The timing controller alternates common voltage levels at frame rate, providing effective anti-peep protection without requiring additional complex voltage control circuits
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
The solution effectively provides an anti-peep function by ensuring that viewers on the side of the display panel see only a limited grayscale or single-grayscale image, effectively preventing unauthorized access to sensitive information.
Implementation Method 1
a liquid crystal layer is interposed between the pixel electrode and the common electrode
Implementation Method 2
the common voltage having a normal voltage level is supplied to the common electrode lines during a first frame period. The common voltage having a complementary high voltage level or a complementary low voltage level is supplied to the common electrode lines during a second frame period
Data Source
AI summary
A display apparatus and a driving method of a display panel thereof are disclosed. The display apparatus includes the display panel and a common voltage setting circuit. The display panel has a plurality of pixels and a plurality of common electrode lines and receives a plurality of pixel voltages. Each of the pixels is coupled to the corresponding common electrode line and receives the corresponding pixel voltage. The common voltage setting circuit is coupled to the common electrode lines. A common voltage having a normal voltage level is supplied to the common electrode lines during a first frame period. The common voltage having a complementary high voltage level or a complementary low voltage level is supplied to the common electrode lines during a second frame period. Each of the pixels receives the same pixel voltage during the first frame period and the second frame period.