Power Conversion Circuit for LCD Viewing Angle Switching
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Solution Overview
Problem
Conventional liquid crystal display (LCD) power conversion circuits, particularly in portable devices, face limitations in driving ability and cost effectiveness for switching viewing angles, which fail to adequately protect user privacy in public settings by allowing images to be easily viewed from different angles.
Innovation Solution
A power conversion circuit with an input terminal, output terminal, switching unit, isolating unit, and multiple power supplies that outputs different DC voltages based on input voltage levels, driving these voltages through an AC voltage generator to control the viewing angle of an LCD by applying varying AC voltages to the viewing angle control electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a programmable power IC is used to generate different DC voltages for viewing angle control, then the viewing angle can be adjusted, but the driving ability is limited and the cost is relatively high
Solution Approach 1:
The power conversion circuit is divided into multiple independent modules: switching unit with multiple transistors, isolating unit with diodes, and output unit with resistors. Each module performs a specific function, allowing the circuit to generate different DC voltages through coordinated operation of segmented components, thereby improving driving ability while maintaining cost-effectiveness
Solution Approach 2:
The patent introduces an isolating unit with diodes as intermediaries between the switching unit and output unit. This isolating unit acts as a mediator that prevents current backflow and ensures stable voltage output, enabling the circuit to drive the viewing angle control electrode effectively without requiring expensive programmable power ICs
2Adaptability or versatility
If a programmable power IC is used to generate different DC voltages for viewing angle control, then the viewing angle can be adjusted, but the cost is relatively high
Solution Approach 1:
The patent replaces expensive programmable power ICs with a cost-effective circuit implementation using standard electronic components: transistors, diodes, and resistors. These inexpensive components are connected in a specific configuration to achieve the same function of generating different DC voltages, significantly reducing manufacturing cost while maintaining viewing angle adjustment capability
Solution Approach 2:
The power conversion circuit is segmented into functional units (switching unit, isolating unit, output unit) that can be manufactured and assembled using standard processes. This segmentation allows for easier manufacturing and lower cost compared to integrating everything into a single programmable power IC
3Ease of operation
If wide viewing angle design is used in LCD, then users can see images without distortion from different angles, but privacy protection is compromised as images can be easily viewed by bystanders
Solution Approach 1:
The patent implements dynamic viewing angle control by applying different AC voltages to the viewing angle control electrode based on user needs. The circuit can switch between wide viewing angle mode (for comfortable viewing) and narrow viewing angle mode (for privacy protection), making the viewing angle adjustable rather than fixed, thus resolving the contradiction between viewing comfort and privacy protection
Solution Approach 2:
The patent changes the voltage parameter applied to the viewing angle control electrode to control the liquid crystal molecule orientation. By adjusting the AC voltage amplitude and frequency, the viewing angle of the LCD can be dynamically changed, allowing the system to switch between wide and narrow viewing angles to balance viewing comfort and privacy protection
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 provides a simple, cost-effective, and strong driving ability to adjust the viewing angle of LCDs from wide to narrow, effectively protecting user privacy by outputting different AC voltages that can be applied to the viewing angle control electrode, enhancing privacy in public places.
Implementation Method 1
When the input terminal is provided with a low level voltage, the switching unit is switched on, the voltage of the second power supply is provided as a first DC voltage to the output terminal via the switching unit and the isolating unit. When the input terminal is provided with a high level voltage, the switching unit is switched off, the voltage of the third power supply is provided as a second DC voltage to the output terminal via the output unit and the isolating unit
Implementation Method 2
driving these voltages through an AC voltage generator to control the viewing angle of an LCD by applying varying AC voltages to the viewing angle control electrode
Implementation Method 3
By applying an AC (alternating current) voltage to the control electrode, an electric filed is generated between the array substrate and the CF substrate to cause the liquid crystal molecules in the liquid crystal layer to rotate, whereby the viewing angle of the LCD is changed
Data Source
AI summary
A power conversion circuit for switching the viewing angle of an LCD, includes an input terminal, an output terminal, a switching unit, an isolating unit, an output unit, a first power supply, a second power supply, and a third power supply. When the input terminal is provided with a low level voltage, the switching unit is switched on, the voltage of the second power supply is provided as a first DC voltage to the output terminal via the switching unit and the isolating unit. When the input terminal is provided with a high level voltage, the switching unit is switched off, the voltage of the third power supply is provided as a second DC voltage to the output terminal via the output unit and the isolating unit, wherein the second DC voltage is higher than the first DC voltage.