Back-Gated Semiconductor Device for Periodic Threshold-Voltage Setting
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Solution Overview
Problem
Variation in electrical characteristics of driving transistors between pixels in self-luminous display apparatuses leads to inconsistent emission luminance and low display quality, and existing solutions for reducing this variation are inefficient and power-consuming.
Innovation Solution
A semiconductor device with a transistor configuration that includes a back gate and specific operational phases to set and maintain the threshold voltage of the transistor, using capacitors to stabilize potential differences and reduce the influence of transistor variations, thereby minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the capacitance of the organic EL element is charged to obtain the threshold voltage of the driving transistor, then the threshold voltage can be obtained, but the period for obtaining the threshold voltage becomes long
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor connected to the back gate before the actual threshold voltage measurement. The capacitor is charged in advance during a preparation phase, so that when the measurement phase begins, the charging process has already been completed or is near completion. This separates the time-consuming charging operation from the critical measurement operation, thereby reducing the period required for obtaining the threshold voltage without sacrificing measurement precision
2Reliability
If a transistor with back gate is used to reduce variation in electrical characteristics, then display quality is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic action by updating the back gate voltage only at specific intervals (e.g., once per frame or once per several frames) rather than continuously. The capacitor connected to the back gate holds the voltage between updates, allowing the system to maintain improved display quality consistency while reducing power consumption by eliminating continuous charging operations. This periodic update strategy balances the need for electrical characteristic stability with energy efficiency
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed semiconductor device effectively reduces the impact of transistor characteristic variations, enhancing display quality and reducing power consumption while maintaining high reliability and display consistency.
Implementation Method 1
The organic EL element has a structure in which a light-emitting layer is interposed between an anode and a cathode, and thus has capacitance
Data Source
AI summary
A novel semiconductor device is provided. The semiconductor device includes a first transistor including a gate and a back gate, and a light-emitting element. The semiconductor device is configured to perform a first operation for supplying a first potential to the back gate of the first transistor, a second operation for fixing a gate potential and a source potential of the first transistor and establishing electrical continuity between a drain and the back gate of the first transistor to set a back gate potential to a second potential corresponding to a difference between the source potential and the gate potential of the first transistor, a third operation for supplying a video signal to the gate of the first transistor, and a fourth operation for supplying a current corresponding to the video signal to the light-emitting element. The second operation is performed less frequently than the third and fourth operations.