Display Drive Apparatus Voltage Compensation for Writing Stability
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Solution Overview
Problem
Self-light emitting-type display apparatuses using active matrix drive methods face issues with insufficient writing, particularly at low brightness levels, due to variations in switching element characteristics, leading to unstable and inaccurate luminance gradation.
Innovation Solution
A display drive apparatus that includes a specific value detection circuit to detect element characteristics and a gradation voltage compensation circuit to generate a compensated gradation voltage, ensuring accurate luminance gradation by compensating for variations in drive element characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current-writing method is used to suppress influence of switching element variation, then light-emitting operation stability is improved, but writing time increases causing insufficient writing at low brightness
Solution Approach 1:
The patent applies preliminary action by pre-charging the data line to a predetermined potential before writing display data. This preliminary charging action reduces the charging time required during the actual writing process, thereby resolving the contradiction between maintaining stable light-emitting operation and reducing writing time for low brightness levels.
2Productivity
If voltage-writing method is used to suppress insufficient writing, then writing speed is improved, but variation in drive current increases due to switching element characteristic variation
Solution Approach 1:
The patent employs feedback by detecting the actual potential of the data line during writing operation and comparing it with the expected potential. Based on this comparison, the system adjusts the writing voltage to compensate for deviations caused by switching element variations, thereby maintaining drive current stability while achieving fast writing speeds through voltage-writing method.
3Manufacturing precision
If data line charging time is increased to ensure sufficient writing, then writing completeness is improved, but display refresh rate decreases
Solution Approach 1:
By performing preliminary charging of the data line before the actual writing operation, the patent ensures that the line is pre-conditioned for optimal signal transmission. This allows the subsequent writing process to be completed faster while still achieving complete and accurate writing, thereby maintaining both writing completeness and high display refresh rate.
Solution Approach 2:
The patent implements periodic action through multi-stage writing processes including preliminary charging, main writing, and potential adjustment phases. This periodic structure allows each phase to be optimized independently, ensuring complete writing in the main phase while keeping overall cycle time short through efficient preliminary and adjustment phases, thus maintaining high refresh rates.
Data Source
AI summary
A display pixel including a light-emitting element and a drive element for supplying current flowing in a current path to the light-emitting element is applied with a detection voltage based on a predetermined unit voltage. Based on a value of current flowing in the current path of the drive element, a specific value corresponding to an element characteristic of the drive element is detected. A gradation voltage corresponding to a luminance gradation of display data is generated. Based on the specific value and the unit voltage, a compensated voltage is generated. By compensating the gradation voltage based on the compensated voltage, a compensated gradation voltage is generated. And the compensated gradation voltage is supplied to the display pixel.