Shift Register Internal Node Initialization Without Extra Wiring

Solution Overview

Problem

Existing shift registers in organic electroluminescence (EL) display devices require initialization of internal nodes before operation to prevent erroneous operation, which increases panel size and requires additional initialization wiring and time.

Innovation Solution

A shift register configuration with depletion mode initialization transistors connected directly or through resistors to internal nodes, allowing initialization without an external initialization signal by applying power supply or ground voltage, enabling node initialization upon power-off.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If initialization wiring lines are provided to initialize internal nodes, then internal nodes can be initialized before operation, but the display panel increases in size and device complexity increases

Engineering Contradiction:

Improveinitialization of internal nodesVSAvoiddisplay panel size

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The shift register automatically initializes its internal nodes using its own power supply voltage without requiring external initialization wiring or control signals. The initialization is performed self-service style by utilizing the natural voltage levels already present in the power supply, eliminating the need for additional initialization infrastructure.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The power supply voltage serves multiple functions: it powers the normal operation of the shift register and simultaneously performs the initialization of internal nodes. This multi-functionality allows the same voltage source to both drive the circuit and reset it, eliminating the need for separate initialization wiring lines.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If initialization wiring lines are provided to initialize internal nodes, then internal nodes can be initialized before operation, but device complexity increases

Engineering Contradiction:

Improveinitialization of internal nodesVSAvoidinitialization wiring lines

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The shift register automatically initializes its internal nodes using its own power supply voltage without requiring external initialization wiring or control signals. The initialization is performed self-service style by utilizing the natural voltage levels already present in the power supply, eliminating the need for additional initialization infrastructure.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The power supply voltage serves multiple functions: it powers the normal operation of the shift register and simultaneously performs the initialization of internal nodes. This multi-functionality allows the same voltage source to both drive the circuit and reset it, eliminating the need for separate initialization wiring lines.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If initialization is performed after power on, then internal nodes can be initialized, but a predetermined amount of time is required

Engineering Contradiction:

Improveinitialization of internal nodesVSAvoidinitialization time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The internal nodes are automatically initialized as soon as power is supplied to the shift register, before any operational signals are applied. This preliminary action ensures that the circuit is in a known state before operation begins, eliminating the need for a separate initialization phase and reducing overall startup time.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The shift register automatically initializes its internal nodes using its own power supply voltage without requiring external initialization wiring or control signals. The initialization is performed self-service style by utilizing the natural voltage levels already present in the power supply, eliminating the need for additional initialization infrastructure.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS11386848B2Shift register, display device, and method for controlling shift register

Publication Date: 2022.07.12 SHARP KK

AI summary

As a scanning line drive circuit of a display device, a shift register having a configuration in which a plurality of unit circuits are connected to each other in multiple stages is used. The unit circuits each include: a plurality of control transistors; an internal node connected to a terminal of one of the plurality of control transistors; and a depletion mode initialization transistor having a first conduction terminal connected directly or through a resistor to the internal node, a second conduction terminal, and a control terminal. One of a power supply voltage and a ground voltage is applied to the second conduction terminal, and the other voltage is applied to the control terminal. The initialization transistor is turned on in a power-off state.