Pixel Circuit Layout for Variable-Frequency Flicker Suppression
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Solution Overview
Problem
Display devices operating in a variable frequency mode experience flicker phenomena due to changes in luminance caused by mismatched frame frequencies, which can be exacerbated by severe hysteresis changes in transistors.
Innovation Solution
A pixel circuit design incorporating specific transistor configurations and shared initialization signal lines, including P-type and N-type transistors, to stabilize transistor states and reduce luminance fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the display device operates in a variable frequency mode to synchronize rendering frequency and operating frequency, then tearing is prevented, but luminance changes occur due to frame frequency changes causing flicker phenomenon
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the initialization voltage level based on the frame frequency. When the frame frequency changes during variable frequency operation, the initialization voltage is adjusted to compensate for the resulting luminance shifts, thereby maintaining stable luminance and preventing flicker while allowing frequency variation to prevent tearing
Solution Approach 2:
The patent implements feedback by monitoring the frame frequency and using this information to adjust the initialization voltage. The system detects changes in operating conditions (frame frequency variations) and responds by modifying the initialization voltage to maintain stable luminance output, creating a closed-loop control system that prevents flicker
2Reliability
If multiple initialization signal lines are used to control different transistors, then transistor states are stabilized, but the number of signal lines increases reducing integration
Solution Approach 1:
The patent applies universality by making the second initialization signal line serve multiple functions: it controls both the fourth transistor in the current pixel circuit and the transistor in the adjacent pixel circuit. This multi-functional signal line reduces the total number of initialization signal lines required while maintaining proper control of all necessary transistors, thereby improving integration without sacrificing transistor state stability
Data Source
AI summary
A pixel circuit includes a light emitting element; a first transistor connected between a first node and the light emitting element, and including a control terminal connected to a second node; a second transistor connected between a corresponding data line among data lines and the first node, and including a control terminal connected to a first scan signal line among scan signal lines; a third transistor connected between the second node and a first initialization voltage line, and including a control terminal connected to a first initialization signal line among initialization signal lines; and a fourth transistor connected between the first node and a bias voltage line, and including a control terminal connected to a second initialization signal line among the initialization signal lines. The second initialization signal line is connected to a control terminal of a transistor of another pixel circuit and connected to the first initialization voltage line.