Bi-Directional Shift Register Circuit for Leakage Current Suppression

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Solution Overview

Problem

Conventional bi-directional shift registers in gate line driving circuits for image display apparatuses suffer from malfunction due to leakage current, require unnecessary end pulse input, and are prone to noise interference, leading to display defects and increased costs.

Innovation Solution

The proposed bi-directional shift register design includes additional transistors to manage node voltages and eliminate the need for end pulse input, using transistors to discharge nodes and manage parasitic capacity, thereby preventing leakage current-induced malfunctions and noise interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional bi-directional shift register design is used, then display pattern change capability is achieved, but malfunction occurs due to leakage current

Engineering Contradiction:

Improvedisplay pattern change capabilityVSAvoidmalfunction due to leakage current

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent extracts and addresses the leakage current problem by adding specific transistors (fifth transistor connected to first node, sixth transistor connected to second node) that actively discharge accumulated leakage charges. This removes the harmful leakage current effect from the system while preserving the bi-directional shift register's display pattern change capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces intermediate discharge transistors as mediators between the floating nodes and ground. These transistors act as intermediaries to safely discharge leakage currents without affecting the normal operation of the main shift register transistors, thus resolving the reliability issue while maintaining adaptability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If conventional bi-directional shift register design is used, then shift direction switching is enabled, but end pulse input is required

Engineering Contradiction:

Improveshift direction switchingVSAvoidend pulse input requirement

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements self-service by enabling the shift register to automatically manage its own state transitions. The added discharge transistors allow the circuit to self-reset and self-manage floating node states without requiring external end pulse inputs, thus simplifying the overall system while maintaining bidirectional shift capability.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Instead of using end pulses to actively reset the circuit state, the patent inverts the approach by allowing the circuit to naturally discharge through the added transistors. This passive discharge mechanism eliminates the need for active end pulse management, reducing device complexity while preserving shift direction switching functionality.

Inventive Principle:

Principle #13The other way round (Inversion)

3Productivity

If conventional bi-directional shift register design is used, then signal transmission is achieved, but noise interference occurs

Engineering Contradiction:

Improvesignal transmissionVSAvoidnoise interference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of floating node susceptibility to noise into a beneficial discharge mechanism. By providing controlled discharge paths through the fifth and sixth transistors, the circuit actively manages the floating node states that would otherwise be vulnerable to noise, thus eliminating noise interference while maintaining signal transmission capability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

4Reliability

If additional transistors are added to suppress leakage current, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improvesuppression of leakage current-induced malfunctionVSAvoidnumber of transistors

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the shift register circuit into functional units with dedicated discharge transistors for each floating node. This segmentation allows the reliability improvement to be localized to specific circuit points without requiring a complete redesign of the entire shift register, thus minimizing the overall increase in device complexity while effectively suppressing leakage current.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS7636412B2Shift register circuit and image display apparatus equipped with the same

Publication Date: 2009.12.22 TRIVALE TECHNOLOGIES LLC

AI summary

Malfunction caused by leakage current of the transistor is prevented in the shift register in which the signal can be shifted bi-directionally. The bi-directional unit shift register includes a transistor Q1 between a clock terminal CK and an output terminal OUT, a transistor Q2 for discharging the output terminal OUT, and transistors Q3, Q4 for providing first and second voltage signals Vn, Vr, which are complementary to each other, to the first node or a gate node of the transistor Q1. Furthermore, a transistor Q5, having a gate connected to a second node or a gate node of the transistor Q2, for discharging the first node is arranged.