Pixel Circuit Voltage Compensation for Display Stability
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Solution Overview
Problem
The stability of the DC reference voltage in pulse amplitude modulation circuits affects the light-emitting stability of light-emitting elements, thereby impacting the display quality of pixel circuits.
Innovation Solution
A pixel circuit that includes a light-emitting element, a light-emitting driver, a data input device, and a reader, where the reader performs voltage compensation on the control terminal of a target compensation transistor using a second data voltage that is twice the value of a first data voltage, ensuring that the driving current is only related to the first data voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If DC reference voltage is used to control driving current in pulse amplitude modulation, then brightness control is achieved, but light-emitting stability deteriorates due to voltage fluctuations
Solution Approach 1:
The patent transforms the driving current control from direct DC voltage control to indirect control through threshold voltage modulation. By changing the control parameter from stable DC reference voltage to dynamically adjustable threshold voltage, the system achieves both brightness control and emission stability. The threshold voltage is adjusted based on the difference between initial and current light-emitting characteristics, compensating for degradation while maintaining stable control.
Solution Approach 2:
The patent implements a feedback mechanism where the control terminal voltage of the compensation transistor is adjusted based on detected changes in light-emitting characteristics. The reader detects the current light-emitting state, compares it with the initial state, and feeds back this information by adjusting the threshold voltage accordingly. This closed-loop feedback ensures that brightness remains controllable while compensating for stability degradation over time.
2Adaptability or versatility
If multiple voltages affect driving current, then circuit functionality is maintained, but display quality deteriorates due to voltage interference
Solution Approach 1:
The patent extracts and isolates the threshold voltage as a separate control parameter from the DC reference voltage. By taking out the threshold voltage control from the general DC voltage control system, the patent eliminates the interference between multiple voltages. The driving current becomes exclusively controlled by the threshold voltage through the compensation transistor, removing the influence of DC reference voltage fluctuations and other voltage variations on display quality.
Data Source
AI summary
A pixel circuit is provided. A reader reads a first data voltage and a threshold voltage of a target compensation transistor on a current path of a driving current in a light-emitting driver to a control terminal of the target compensation transistor during a read period. During a light-emitting period, the reader uses a second data voltage to compensate the control terminal of the target compensation transistor, which ensures that the driving current is only related to the first data voltage. The second data voltage is twice voltage value of the first data voltage.