Bi-directional LCD Driving Circuit with Shift Register Scanning
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Solution Overview
Problem
Conventional LCD panels have a fixed driving direction, limiting the flexibility to scan images in multiple orientations, such as landscape or portrait, which restricts the ability to freely set the direction of the display device.
Innovation Solution
A bi-directional driving circuit for LCD panels is introduced, allowing for forward and backward scanning without a separate input pad, utilizing a shift register structure with specific p-MOS transistors and capacitors to switch start pulse signals and clock signals across blocks, enabling flexible scanning directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed driving direction is used in conventional LCD panels, then the circuit structure is simple, but the adaptability to different orientations (landscape/portrait) is limited
Solution Approach 1:
The patent applies the dynamics principle by making the driving direction changeable through control signals. The shift register circuit can dynamically switch between forward and backward scanning directions based on external control, allowing the LCD panel to adapt to different orientations without requiring separate input pads for each direction. This dynamic capability resolves the contradiction between adaptability and circuit complexity.
Solution Approach 2:
The patent implements universality by designing a single shift register circuit that can perform multiple functions - both forward and backward scanning - using the same input pad and circuit structure. By controlling the start pulse input and clock signal phases, the same circuit achieves bidirectional driving capability, eliminating the need for separate circuits for different orientations and thus maintaining circuit simplicity while enhancing adaptability.
2Adaptability or versatility
If separate input pads are added for forward and backward scanning, then bi-directional scanning capability is achieved, but the number of input pads and device complexity increases
Solution Approach 1:
The patent makes the single input pad universal by designing the shift register to accept start pulses and control signals that determine scanning direction. The same input pad serves both forward and backward scanning functions by varying the control signal phases, thereby achieving bi-directional capability without increasing the quantity of input pads.
Solution Approach 2:
The patent achieves direction switching by changing the phase parameters of clock signals and the timing of start pulses rather than adding physical components. By altering signal phase and timing parameters, the circuit transitions between forward and backward scanning modes, maintaining a minimal number of input pads while achieving full bi-directional functionality.
Data Source
AI summary
A bi-directional driving circuit of a liquid crystal display (LCD) panel is disclosed, in which forward scanning and backward scanning are available. In a bi-directional driving circuit of an LCD panel having a plurality of blocks, each block includes a first start pulse input terminal to which a start pulse or an output signal of a previous block is input and a second start pulse input terminal to which the start pulse or an output signal of a next block is input. Also, each block includes a first switching portion switching a start pulse signal applied to an input terminal of a first block among the blocks and switching an output signal of a previous block, which is applied to input terminals of the other blocks and a second switching portion switching a start pulse signal applied to an input terminal of the last block and switching an output signal of a previous block, which is applied to input terminals of the other blocks.