OLED Display Unit Brightness Compensation Circuit
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Solution Overview
Problem
In OLED display panels, the brightness of display units decreases over time due to increased light-emitting time, leading to non-uniform image brightness and 'sticking' images, as the driving current diminishes for the same data signal.
Innovation Solution
A display unit comprising a switch unit, a driving unit, a light-emitting unit, and a control circuit, where the control circuit adjusts the voltage at the first node based on the voltage at the second node, using transistors and capacitors to maintain or increase the driving current and brightness of the light-emitting diode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the light-emitting time of the LED is increased, then the display unit can maintain image display continuity, but the brightness of the LED decreases leading to non-uniform image brightness
Solution Approach 1:
The control circuit monitors the voltage at the second node (which reflects LED brightness degradation) and provides feedback to adjust the voltage at the first node. This feedback mechanism dynamically compensates for brightness decay over time, ensuring uniform image brightness throughout the display period.
Solution Approach 2:
The invention changes the voltage parameter at the first node dynamically based on the voltage at the second node. By adjusting this voltage parameter in response to LED aging effects, the system maintains consistent driving current and brightness levels throughout the light-emitting period.
2Device complexity
If the same data signal is applied to all display units, then the control circuitry is simplified, but brightness uniformity deteriorates due to cumulative light-emitting time effects
Solution Approach 1:
The control circuit automatically compensates for brightness degradation without requiring external intervention or complex control signals. The circuit uses the voltage at the second node as a natural indicator of LED aging and self-adjusts the voltage at the first node to maintain brightness uniformity.
Solution Approach 2:
The control circuit establishes a feedback loop where the voltage at the second node (reflecting LED brightness state) is continuously monitored and used to adjust the voltage at the first node. This enables automatic brightness compensation while keeping the control circuitry relatively simple.
Data Source
AI summary
A display unit comprising a first switch unit, a driving unit, a light-emitting unit, and a control circuit. The first switch unit has a control electrode coupled to a scan line, a first electrode coupled to a data line, and a second electrode coupled to a first node. The driving unit has a control electrode coupled to the first node, a first electrode coupled to a first voltage source, and a second electrode coupled to a second node. The light-emitting unit is coupled between the second node and a second voltage source. The control circuit is coupled between the first and second nodes and adjusts a voltage at the first node according to a voltage at the second node.