Pixel Driving Circuit for Display Panel Brightness Stability
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Solution Overview
Problem
Self-luminous devices in display panels face inconsistencies in turn-on voltages and photoelectric conversion properties due to variations in fabrication processes, affecting display quality.
Innovation Solution
A pixel driving circuit comprising a driving control sub-circuit and a time control sub-circuit, which includes transistors and capacitors, is used to manage data signals and power supply voltages to ensure consistent operation of elements like current mode light-emitting diodes, controlling both the magnitude and duration of driving signals to achieve stable brightness and gray scale representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If self-luminous devices are used in display panels, then brightness and color gamut are improved, but turn-on voltage consistency deteriorates due to fabrication process variations
Solution Approach 1:
The pixel driving circuit employs feedback mechanisms through the driving control sub-circuit and time control sub-circuit that monitor and adjust the driving signals based on the actual state of the self-luminous device. The circuit uses the common voltage signal terminal and variable resistance characteristics to create a feedback loop that compensates for turn-on voltage variations, ensuring consistent operation despite fabrication process differences.
Solution Approach 2:
The patent utilizes parameter changes by varying the common voltage signal within a set voltage range to dynamically adjust the operating conditions of the self-luminous device. The time control sub-circuit modifies the driving parameters (voltage and time) based on the actual turn-on voltage of each device, transforming a static driving approach into a dynamic one that adapts to individual device characteristics.
2Illumination intensity
If current density is increased to improve brightness, then luminous efficiency is improved, but power consumption increases
Solution Approach 1:
The pixel driving circuit implements periodic action by controlling the self-luminous device to operate in discrete time intervals rather than continuously. The time control sub-circuit applies driving signals during specific periods and maintains the device in an off state during other periods, enabling duty cycle control that reduces average power consumption while maintaining perceived brightness through persistence of vision.
Solution Approach 2:
The patent applies dynamics by making the driving parameters variable rather than fixed. The common voltage signal varies within a set voltage range, and the driving time is dynamically adjusted based on the gray scale requirements and device characteristics. This dynamic control allows the system to optimize the balance between luminous efficiency and power consumption for each operating condition.
3Illumination intensity
If driving time is extended to improve gray scale representation, then brightness stability is improved, but response time increases
Solution Approach 1:
The pixel driving circuit uses preliminary action by pre-charging capacitors and preparing the driving transistors before the actual driving signal is applied. The driving control sub-circuit performs preliminary setup operations during the scanning phase, so that when the driving signal is activated, the device can respond more quickly without sacrificing brightness stability during the actual emission period.
Data Source
AI summary
A pixel driving circuit includes: a driving control sub-circuit configured to write at least a first data signal into a first driving sub-circuit in response to a first scanning signal and cause a driving transistor to output a driving signal to an element to be driven according to the first data signal and a first power supply voltage signal in response to an enable signal, and a time control sub-circuit configured to write at least a second data signal into a second driving sub-circuit in response to a second scanning signal and cause the second driving sub-circuit to be connected to a second power supply voltage signal terminal and the element in response to the enable signal. The second driving sub-circuit is configured to output a second power supply voltage signal to the element in response to the second data signal and a common voltage signal.