EL Display Gate Driver Circuit VT Voltage Stabilization
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Solution Overview
Problem
Conventional EL display apparatuses experience variations in the rise voltage (VT voltage) of drive transistors, leading to changes in current flow through EL elements, causing brightness inconsistencies and color unevenness, and result in transistor deterioration due to alternating anode voltage loads.
Innovation Solution
The EL display apparatus incorporates a gate driver circuit that applies specific voltages to switch transistors to stabilize the drive transistor state, using a reference voltage and reverse bias voltage to prevent VT voltage changes, ensuring consistent current supply to EL elements and reducing transistor load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional EL display apparatus uses drive transistor to supply current to EL element, then the display can operate, but the rise voltage (VT voltage) of drive transistor varies causing brightness inconsistencies and color unevenness
Solution Approach 1:
The gate driver circuit applies a reset voltage to the gate terminal of the drive transistor before the light emission current is supplied, preliminarily setting the transistor to a known state. This preliminary action prevents VT voltage variations from affecting the subsequent current supply to the EL element, ensuring brightness consistency across the display.
2Productivity
If conventional EL display apparatus applies alternating anode voltage loads to drive transistor, then the transistor can control light emission, but the transistor deteriorates due to load variations
Solution Approach 1:
The gate driver circuit applies a reset voltage to the gate terminal before the light emission phase, preliminarily establishing a stable operating point for the drive transistor. This preliminary conditioning reduces the impact of subsequent alternating anode voltage loads, minimizing stress on the transistor and extending its operational lifespan.
3Stability of the object's composition
If gate driver circuit applies multiple voltages to gate terminal of drive transistor, then the VT voltage can be stabilized, but the circuit complexity increases
Solution Approach 1:
The gate driver circuit is divided into separate functional units: a reset voltage generation unit that applies a reset voltage to the gate terminal, and a light emission control unit that supplies the light emission current. This segmentation allows each unit to perform its specific function with simple circuitry, avoiding the need for a complex multi-voltage system while still achieving stable drive transistor operation.
Data Source
AI summary
An EL display apparatus includes pixels each including an EL element, a drive transistor, and a switch transistor, and further includes: a source driver circuit; a source signal line; a gate driver circuit; a first gate signal line; and a second gate signal line, wherein the gate driver circuit applies, to the first gate signal line, a first voltage or a second voltage, and the drive transistor is placed in a first state by the gate driver circuit applying the first voltage to the gate terminal of the drive transistor while the switch transistor is on, and is placed in a second state by the gate driver circuit applying the second voltage to the gate terminal of the drive transistor while the switch transistor is on.