Display Panel Row-Line Driving Circuit for Crosstalk and Power
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Solution Overview
Problem
Existing display panels using inorganic light-emitting elements face issues with color reproducibility, power consumption, luminance uniformity, horizontal crosstalk, and voltage drop due to deviations in threshold voltage and mobility of driving transistors, as well as the influence of sweep rods.
Innovation Solution
A display apparatus with a pixel array and sub-pixel circuits that utilize a progressive driving method, where image data voltages are set and driving currents are provided in a row line order, using capacitors and transistors to control current timing and magnitude, and a sensing unit to correct voltages based on current sensing data, thereby compensating for transistor deviations and optimizing power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If Pulse Amplitude Modulation (PAM) driving method is used to express gradation of sub-pixels, then power consumption can be controlled, but color reproducibility deteriorates due to wavelength changes with driving current magnitude
Solution Approach 1:
The patent transitions from static PAM driving to dynamic PWM driving, where the light emission duration is dynamically adjusted while maintaining constant current magnitude. This dynamic time-based control eliminates wavelength shifts caused by current variations, ensuring consistent color reproduction across different brightness levels while maintaining power efficiency through controlled emission timing.
Solution Approach 2:
The patent changes the controlling parameter from current magnitude (PAM) to time duration (PWM). By maintaining constant current magnitude and varying only the light emission time, the system achieves both power consumption control and stable color reproduction, as the wavelength remains unchanged when current magnitude is constant.
2Illumination intensity
If driving current magnitude is increased to improve luminance, then color reproducibility deteriorates due to wavelength shift, but if driving current is decreased to maintain color, then luminance decreases
Solution Approach 1:
The patent employs dynamic time-based control where luminance is adjusted by varying the duration of light emission rather than changing current magnitude. This allows full luminance range control while maintaining constant current levels that ensure accurate color reproduction, resolving the trade-off between brightness and color accuracy.
Solution Approach 2:
The patent uses periodic light emission cycles with variable duty ratios to control luminance. By switching the light-emitting element on and off in periodic cycles with different on-times, the system achieves various brightness levels without changing the current magnitude, thereby maintaining consistent wavelength and color reproduction.
3Device complexity
If threshold voltage deviation of driving transistor is not compensated, then device complexity is reduced, but luminance uniformity deteriorates across the display panel
Solution Approach 1:
The patent implements preliminary threshold voltage compensation by measuring the threshold voltage of each driving transistor during a test period and storing compensation values before normal display operation. This preliminary calibration ensures uniform luminance across the panel during subsequent PWM driving without adding complex real-time compensation circuits.
Solution Approach 2:
The patent incorporates feedback mechanisms where the driving circuit receives threshold voltage information from sensing circuits and adjusts driving parameters accordingly. This feedback loop compensates for transistor variations, ensuring uniform luminance across the display panel while maintaining relatively simple circuit architecture.
4Use of energy by moving object
If progressive driving method is implemented to reduce power consumption, then power usage decreases, but horizontal crosstalk may increase due to sweep rod influence
Solution Approach 1:
The patent applies preliminary voltage compensation to the sweep rod before progressive PWM driving to counteract its influence on horizontal crosstalk. By pre-adjusting the sweep rod voltage based on measured deviations, the system eliminates crosstalk issues that would otherwise be exacerbated by the row-by-row progressive driving method, enabling clean power-efficient operation.
Data Source
AI summary
A display apparatus includes a display panel including: a pixel array in which pixels including a plurality of light-emitting elements are arranged in a plurality of row lines and sub-pixel circuits provided for each of the plurality of light-emitting elements and providing a driving current to the light-emitting elements. The display apparatus also includes a drive unit is configured to: set image data voltages to the sub-pixel circuits of the display panel in a row line order during a data setting period for each row line; and drive the sub-pixel circuits to provide the driving current to the light-emitting elements of the pixel array in the row line order based on a sweep signal sweeping from a first voltage to a second voltage and the set image data voltages during a light-emitting period for each row line.