Display Drive Device Threshold Compensation Circuit
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Solution Overview
Problem
In light emitting element display devices, fluctuations in the threshold value of current control thin film transistors over time lead to inconsistent driving current for light emitting elements, affecting gradation control and image quality.
Innovation Solution
A display drive device with a specific value detecting section and voltage adjusting circuit that compensates for characteristic fluctuations by detecting element characteristics and generating correction gradation voltages for each display pixel, ensuring consistent luminance across a long period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a current control thin film transistor is used to supply current to light emitting elements for gradation control, then high image quality with high luminance and high contrast can be achieved, but the threshold value of the transistor fluctuates over time causing inconsistent driving current
Solution Approach 1:
The patent applies preliminary action by detecting the threshold value of the current control transistor in advance during a threshold detection period before normal display operation. The detected threshold value is stored and used to generate corrected gradation voltages during subsequent display periods, thereby compensating for threshold fluctuations before they affect image quality.
Solution Approach 2:
The patent implements feedback by continuously monitoring the threshold value of the transistor and using this information to adjust the gradation voltage applied to the light emitting element. The correction voltage is calculated based on the detected threshold value, creating a closed-loop system that maintains consistent driving current despite threshold fluctuations.
2Ease of operation
If the same gradation voltage is supplied to display pixels, then simplified driving control is achieved, but fluctuation in transistor threshold value causes fluctuation in driving current and inconsistent luminance
Solution Approach 1:
The patent applies local quality by providing individualized correction voltages to each display pixel based on its specific transistor characteristics. Instead of using a uniform gradation voltage for all pixels, the system detects and compensates for threshold variations in each transistor, thereby maintaining luminance consistency across the display while preserving the simplicity of the driving control architecture.
3Reliability
If correction gradation voltage is generated for each display pixel based on detected threshold value, then luminance consistency is maintained over long period, but additional detection and correction circuits are required
Solution Approach 1:
The patent applies universality by designing correction circuits that can be integrated into the existing pixel structure and driving architecture. The threshold detection function is incorporated into the existing data writing circuitry, and the correction voltage generation uses the same voltage control mechanisms already present in the display system, thereby minimizing additional complexity while achieving long-term luminance stability.
Data Source
AI summary
A predetermined voltage is supplied to a voltage supply line connected in common to respective current paths of driving elements of each of a plurality of display pixels. Adjustment voltages based on a predetermined unit voltage are sequentially applied to a plurality of data lines connected to the display pixels. Specific values corresponding to element characteristics of the respective driving elements of the display pixels are sequentially detected based on a value of a detection value that is a potential difference between a data line and the voltage supply line or a value of a current flowing into the voltage supply line. Correction gradation voltages are generated for each pixel by correcting a gradation voltage having a voltage value corresponding to display data for the pixel based on the specific value for the pixel, so as to compensate for characteristic fluctuation of the driving element of the pixel.