Shift Register Switch Circuit for Low-Leakage LCD Gate Driving

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Solution Overview

Problem

Traditional liquid crystal displays (LCDs) face high power consumption and reduced panel lifetime due to reverse leakage currents from thin film transistors, and the integration of shift register circuits in display panels leads to low signal transmitting ability and degraded display quality.

Innovation Solution

A shift register circuit with a bi-directional scan mechanism using a combination of transistors in switch devices to reduce turn-on resistance and suppress reverse leakage currents, enhancing driving ability and reducing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If traditional thin film transistors are used in switch devices, then device complexity is reduced, but reverse leakage currents increase causing high power consumption and high panel working temperature

Engineering Contradiction:

Improveswitch device structureVSAvoidpower consumption

Core Design Contradiction:

Device complexityVSUse of energy by moving object

Solution Approach 1:

The patent merges multiple transistors (first transistor and second transistor) into a single switch device structure. The first transistor includes first and second active regions with source/drain electrodes, while the second transistor includes third and fourth active regions with source/drain electrodes. These transistors are combined such that the source/drain electrodes of the first transistor serve as gate electrodes for the second transistor, creating an integrated switch device that reduces reverse leakage currents and power consumption while maintaining structural simplicity.

Inventive Principle:

Principle #5Merging (Combining)

2Ease of manufacture

If traditional thin film transistors are used in switch devices, then manufacturing simplicity is maintained, but panel working temperature increases reducing panel lifetime

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidpanel lifetime

Core Design Contradiction:

Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The patent combines multiple transistor functions into a single integrated switch device structure where the source/drain electrodes of the first transistor serve dual purposes as both current conduction paths and gate electrodes for the second transistor. This merged structure reduces reverse leakage currents and panel working temperature, thereby extending panel lifetime while maintaining ease of manufacture through a unified fabrication process.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If shift register stages are sequentially arranged in a lengthy border area, then integration in display panel is achieved, but signal transmitting ability degrades due to turn-on resistance

Engineering Contradiction:

Improveintegration capabilityVSAvoidsignal transmitting ability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent merges multiple transistor elements into a compact switch device where the first transistor's source/drain electrodes function as gate electrodes for the second transistor. This integrated structure reduces the turn-on resistance of the switch device, thereby improving signal transmitting ability while maintaining the capability for integration in display panel border areas.

Inventive Principle:

Principle #5Merging (Combining)

4Power

If multiple transistors are combined in switch devices to reduce turn-on resistance, then driving ability improves, but device complexity increases

Engineering Contradiction:

Improvedriving abilityVSAvoidswitch device structure

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent combines multiple transistor elements (first transistor with first and second active regions, second transistor with third and fourth active regions) into a unified switch device structure. The key innovation is that the source/drain electrodes of the first transistor serve dual functions as both current conduction paths and gate electrodes for the second transistor. This merging approach reduces turn-on resistance and improves driving ability while avoiding excessive complexity through functional integration.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The source/drain electrodes of the first transistor serve multiple functions: they conduct current in the first transistor and simultaneously serve as gate electrodes for the second transistor. This multi-functionality reduces the total number of separate electrode structures needed, improving driving ability while controlling device complexity through universal element usage.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20120170707A1Switch device and shift register circuit using the same

Publication Date: 2012.07.05 AU OPTRONICS CORP

AI summary

A shift register circuit includes plural shift register stages for providing plural gate signals. Each shift register stage includes an input unit and a pull-up unit. The pull-up unit is utilized for pulling up a gate signal according to a system clock and a driving control voltage. The input unit is employed for outputting the driving control voltage according to a control signal and an input signal. The input unit includes a switch device having a first transistor and a second transistor. The first transistor has a first end for receiving the input signal, a gate end for receiving the control signal, and a second end. The second transistor has a first end electrically connected to the second end of the first transistor, a gate end electrically connected to the first end of the first transistor, and a second end for outputting the driving control voltage.