Shift Register Voltage Stabilizing Transistor Signal Overlap
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Solution Overview
Problem
Shift registers in liquid crystal displays (LCDs) experience signal distortions due to overlapping pulse signals, leading to color shifts during image display, as two rows or columns of gate/data lines may be scanned simultaneously.
Innovation Solution
A shift register design featuring a plurality of units connected in stages, each receiving inverse clock signals, with an output circuit, input circuit, and logic circuit to manage clock and voltage signals, preventing signal overlap by controlling transistor states to maintain stable output levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional shift register unit uses PMOS transistors for clock inversion circuits without additional control mechanisms, then the circuit structure remains simple, but signal distortions occur due to overlapping pulse signals from adjacent shift register units
Solution Approach 1:
The patent introduces a voltage stabilizing transistor as an intermediary element between the input circuit and output circuit. This transistor acts as a mediator that controls the output signal level based on clock phases, preventing direct signal overlap while maintaining circuit simplicity. The voltage stabilizing transistor receives control signals from the input circuit and adjusts the output accordingly, resolving the contradiction between simple structure and signal stability.
Solution Approach 2:
The patent utilizes periodic clock signals with alternating phases (first clock signal and second clock signal) to control the operation of adjacent shift register units. By synchronizing the operation periods of adjacent units through periodic clocking, the patent ensures that one unit is always in a high-impedance state while the other drives the output, preventing signal overlap. This periodic control mechanism maintains signal stability without significantly increasing circuit complexity.
2Productivity
If adjacent shift register units operate simultaneously without phase control, then the scanning speed increases, but signal distortions and color shifts occur due to overlapping pulse signals
Solution Approach 1:
The patent implements periodic operation of adjacent shift register units by applying clock signals with alternating phases. The first shift register unit operates during the high phase of the first clock signal while the second unit operates during the high phase of the second clock signal. This periodic alternation maintains high scanning speed by ensuring continuous operation across units while preventing signal overlap that would degrade display quality.
Solution Approach 2:
The patent introduces dynamic control of transistor states based on clock phases. The voltage stabilizing transistor dynamically switches between conducting and non-conducting states according to the phase of the clock signal, enabling the output circuit to adapt its behavior. This dynamic control allows adjacent units to operate simultaneously at high speed while maintaining signal integrity through phase-dependent impedance modulation.
3Reliability
If the shift register unit uses a voltage stabilizing transistor controlled by clock phases, then signal overlap is prevented and display quality improves, but the circuit complexity increases
Solution Approach 1:
The voltage stabilizing transistor serves as an intermediary element that adds minimal complexity to the circuit while providing significant signal stability improvement. Rather than redesigning the entire output circuit, the patent inserts this single controlling element that manages the interaction between the input circuit and output circuit. This intermediary approach achieves reliable signal stabilization with minimal increase in device complexity.
Solution Approach 2:
The voltage stabilizing transistor performs multiple functions within a single component: it acts as a switch controlled by clock phases, a signal level regulator, and an impedance controller. By making this element multi-functional, the patent achieves comprehensive signal stability control without proportionally increasing circuit complexity. The same transistor structure is used across all shift register units, providing universal applicability.
Data Source
AI summary
An exemplary shift register includes a plurality of shift register units, each of which includes an output circuit, an input circuit, and a logic circuit. The output circuit includes a clock transistor, a voltage stabilizing transistor, and an input circuit for receiving signals output by a previous shift register unit. The logic circuit receives signals output by the input circuit. When the input circuit outputs signals to switch on the clock transistor, the logic circuit outputs a low level voltage signal to shut off the voltage stabilizing transistor. Thus, the output circuit outputs signals via the clock circuit. On the other hand, when the input circuit outputs signals to shut off the clock transistor, the logic circuit outputs a high level voltage signal to turn on the voltage stabilizing transistor, so as to maintain the output circuit to output low level voltage signal.