Display Device Compensation Transistor Reduces Capacitance Voltage Dependence
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Solution Overview
Problem
Existing organic electroluminescent (EL) display devices face complexity in manufacturing due to the use of crosstalk cancel switches with different conductivity types, leading to luminance unevenness issues.
Innovation Solution
A display device configuration with pixel circuits that include a drive transistor, a capacitor, a write transistor, and a compensation transistor of the same conductivity type, where the compensation transistor's gate electrode is connected to the data line and at least one of its drain or source electrodes is connected to the write control line, reducing capacitance voltage dependence and luminance unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a crosstalk cancel switch with different conductivity type is used, then lateral crosstalk is reduced, but manufacturing process complexity increases
Solution Approach 1:
The patent uses transistors of the same conductivity type (all n-channel or all p-channel) for both the pixel switch and crosstalk cancel switch, ensuring homogeneity in device characteristics and simplifying the manufacturing process while maintaining crosstalk reduction effectiveness
Solution Approach 2:
The patent modifies the circuit configuration by connecting the crosstalk cancel switch in parallel with the pixel switch and adjusting the gate control signals to achieve crosstalk reduction without changing transistor conductivity types, thereby resolving the contradiction between performance and manufacturing complexity
2Ease of manufacture
If capacitance voltage dependence is high, then manufacturing is simpler, but luminance unevenness increases
Solution Approach 1:
The compensation transistor acts as a feedback mechanism that senses the voltage drop on the write control line caused by capacitance variations and compensates for it by adjusting the write signal, thereby eliminating luminance unevenness without complicating the manufacturing process
Solution Approach 2:
The compensation transistor serves as an intermediary element between the write control line and the pixel circuit, mediating the effect of capacitance voltage dependence by counterbalancing its influence and preventing luminance unevenness
Data Source
AI summary
A plurality of pixel circuits included in a display device each includes: a drive transistor; a capacitor connected to a gate electrode and a source electrode of the drive transistor; a light-emitting element which is driven by the drive transistor; a write transistor having a gate electrode connected to a write control line for transmitting a write signal, one of a drain electrode and a source electrode connected to a data line for transmitting a data voltage corresponding to luminance, and the other of the drain electrode and the source electrode connected to the gate electrode of the drive transistor; and a compensation transistor having a gate electrode connected to the data line, and at least one of a drain electrode and a source electrode connected to the write control line, the compensation transistor being of same conductivity type as the write transistor.