Scan Line Driver Circuit Reduces Through Current
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Solution Overview
Problem
Active matrix display devices with scan line driver circuits formed using either n-channel or p-channel transistors experience increased power consumption due to significant through current when inverters are formed using these transistors, leading to inefficiencies in signal output to scan lines.
Innovation Solution
The implementation of a display device with pulse output circuits and inverted pulse output circuits, where the pulse output circuits supply signals to one set of scan lines and the inverted pulse output circuits supply inverted signals to another set, utilizing capacitive coupling to maintain signal integrity without additional power consumption, thereby reducing through current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If inverters are formed using n-channel or p-channel transistors in scan line driver circuits, then signal inversion can be achieved, but power consumption increases due to significant through current
Solution Approach 1:
The patent extracts the inversion function from traditional inverter circuits and implements it through capacitive coupling mechanisms in the pulse output circuits. By removing the dedicated inverter structure and using capacitive charge transfer to achieve signal inversion, the through current is eliminated while maintaining the inversion capability.
Solution Approach 2:
The patent replaces the electrical field-based inverter operation (which causes through current) with a capacitive coupling mechanism that uses charge transfer through capacitors. This substitution eliminates the continuous current flow while achieving the same signal inversion function through discrete charge transfer events.
2Use of energy by moving object
If scan line driver circuits use only n-channel transistors, then power consumption is reduced compared to using both types, but the high potential supplied to scan lines is lower than the power supply potential due to threshold voltage drop
Solution Approach 1:
The patent changes the operational parameters of the n-channel transistors by using capacitive coupling to boost the gate potential dynamically. During the switching operation, the capacitor charges to the full power supply potential and then transfers this charge to the gate, temporarily raising the gate potential above the normal supply level to overcome the threshold voltage drop and ensure reliable high potential output.
3Adaptability or versatility
If two kinds of scan line driver circuits are provided to control separately provided switches in pixels, then switching control flexibility is improved, but device complexity increases
Solution Approach 1:
The patent merges the functions of multiple scan line driver circuits into a single integrated pulse output circuit. By using capacitive coupling to generate multiple phased signals from a single circuit architecture, the patent achieves the flexibility of separate control while reducing the overall complexity and component count.
Solution Approach 2:
The patent implements a universal pulse output circuit that can generate multiple different scan line control signals with different phases and timing characteristics. This multi-functional circuit replaces what would traditionally require multiple separate driver circuits, achieving versatility without proportional increases in complexity.
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
This configuration reduces power consumption by controlling the operation of inverted pulse output circuits using signals from pulse output circuits, allowing for efficient signal transmission without generating additional signals, thus minimizing power loss.
Implementation Method 1
by utilizing at least one of capacitive coupling between a gate and a source of the first transistor and capacitive coupling between a gate and a source of the second transistor
Data Source
AI summary
To reduce power consumption of a display device including a scan line driver circuit formed using either n-channel transistors or p-channel transistors when the scan line driver circuit outputs, to one of two kinds of scan lines, inverted or substantially inverted signals of signals output to the other of the two kinds of scan lines. The display device includes a plurality of pulse output circuits each of which outputs a signal to one of two kinds of scan lines and a plurality of inverted pulse output circuits each of which outputs, to the other of the two kinds of scan lines, an inverted or substantially inverted signal output from the each of the pulse output circuits. The plurality of inverted pulse output circuits operate with signals used for the operation of the plurality of pulse output circuits. Thus, through current generated in the inverted pulse output circuits can be reduced.