Pixel Compensation Circuit for Mini LED Brightness Control
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Solution Overview
Problem
Existing pixel compensation circuits face challenges in controlling current for high-brightness LED backlight panels, particularly due to voltage drops and line resistance, leading to non-uniform brightness and increased power consumption.
Innovation Solution
A pixel compensation circuit is designed with a control unit that manages the voltage drop time based on data voltage values, utilizing a specific configuration of transistors and capacitors to control the gray scale of light emitting diodes, reducing the number of transistors on the light-emitting path and compensating for threshold voltage variations, thereby achieving accurate current control and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a large current is used to drive mini LEDs for high brightness, then the luminous intensity is improved, but the voltage drop increases making current control difficult
Solution Approach 1:
The patent implements a feedback mechanism where the actual voltage at the LED anode is sensed and used to adjust the drive current dynamically. The compensation circuit monitors the voltage drop and adjusts the current to maintain precise control despite variations in voltage drop, thereby resolving the contradiction between high brightness and current control accuracy.
Solution Approach 2:
The patent changes the operating parameters by dynamically adjusting the drive current based on the actual voltage conditions. By modifying the current parameter in real-time according to voltage drop variations, the system maintains accurate current control while operating at high brightness levels required for mini LED backlighting.
2Measurement precision
If the cross voltage of the driving transistor is increased to improve current control, then the current control accuracy is improved, but the power consumption increases
Solution Approach 1:
The patent employs dynamic adjustment of the driving transistor's cross voltage rather than using a fixed high voltage. The compensation circuit dynamically modulates the voltage to achieve accurate current control only when necessary, reducing the average power consumption while maintaining current control precision throughout the display operation.
3Manufacturing precision
If more transistors are added to compensate for threshold voltage variations, then the manufacturing precision is improved, but the device complexity increases
Solution Approach 1:
The patent merges the compensation function into the existing driving transistor structure by using the same transistor to perform both driving and compensation functions. The compensation is achieved through circuit configuration and control methodology rather than adding separate compensation transistors, thereby improving threshold voltage compensation accuracy without significantly increasing device complexity.
4Illumination intensity
If the drive current for mini LEDs is increased, then the luminous intensity is improved, but the voltage source offset due to line resistance increases causing pixel voltage variations
Solution Approach 1:
The patent applies local quality by providing individualized current control for each pixel based on its specific voltage conditions. The compensation circuit adjusts the drive current locally for each pixel according to its actual voltage at the anode, ensuring uniform luminous intensity across all pixels despite variations in line resistance and voltage drop.
Data Source
AI summary
A pixel compensation circuit including a light emitting diode, a drive unit, a control unit, a data write-in unit, a reset unit, and a pull-down unit is disclosed. The control unit is configured to control a voltage drop time of the first node according to a data voltage value received by the data write-in unit, so as to control a gray scale of the light emitting diode. The data write-in unit includes a first transistor, a second transistor, a third transistor and a capacitor. The first transistor is connected to a first voltage source and a second node. The second transistor is connected to the second node and a third node. The third transistor is connected to the third node and a data input source. The first capacitor is connected to the second node and a first reference voltage source.