Semiconductor Device Mobility Compensation via Preliminary Charge Discharge
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Solution Overview
Problem
Existing organic EL display technologies face issues with image unevenness due to variations in transistor threshold voltage and mobility, leading to insufficient compensation periods and increased complexity in signal driving methods, which affect display performance and reliability.
Innovation Solution
A semiconductor device with a transistor and a capacitor element connected to its gate, where charge is held and discharged to compensate for variations in current and mobility, allowing for extended input periods and reduced influence from waveform distortions, enabling both line and dot sequential driving on the same substrate with reduced power consumption and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mobility compensation is performed while image signal is input in a pixel, then mobility variation is compensated, but image signal cannot be input to other pixels and process time becomes insufficient
Solution Approach 1:
The patent performs mobility compensation in a preliminary period before the image signal input period. Specifically, the mobility compensation is executed in a first period, and the image signal is input in a second period that follows, ensuring that compensation is completed in advance without interfering with the image signal input process to other pixels
Solution Approach 2:
The gate selection period is segmented into distinct time periods: a first period for mobility compensation, a second period for image signal input, and potentially a third period for threshold voltage compensation. This segmentation allows each process to be performed sequentially with sufficient time allocation, preventing time conflicts
2Manufacturing precision
If mobility compensation period is extended to ensure accurate compensation, then compensation accuracy improves, but other processes (image signal input, threshold voltage acquisition) have insufficient time
Solution Approach 1:
Mobility compensation is performed in advance in a dedicated first period before the image signal input period. This preliminary action ensures that the compensation process has sufficient time to complete accurately without encroaching on the time allocated for image signal input to multiple pixels
Solution Approach 2:
The patent implements a periodic driving scheme where mobility compensation, image signal input, and threshold voltage compensation are performed in alternating periodic intervals. This allows each process to be executed thoroughly in its designated period while maintaining overall system productivity through efficient time multiplexing
3Manufacturing precision
If mobility is compensated while image signal is input, then mobility variation is reduced, but compensation is influenced by waveform distortion of image signal
Solution Approach 1:
The patent extracts the mobility compensation process from the image signal input period and performs it in a separate, dedicated first period. This separation removes the harmful influence of image signal waveform distortion from the compensation process, ensuring that mobility compensation is performed on a clean signal without superimposed image data variations
4Manufacturing precision
If line sequential driving is used to compensate mobility during image signal input, then mobility compensation is possible, but dot sequential driving cannot be performed and circuit structure becomes complicated
Solution Approach 1:
The patent performs mobility compensation in a preliminary period before image signal input, rather than attempting to perform it simultaneously during image signal input. This approach eliminates the need for complex line sequential driving circuits and allows the use of simpler dot sequential driving methods, reducing overall circuit complexity while maintaining compensation accuracy
Data Source
AI summary
The semiconductor device includes a transistor and a capacitor element which is electrically connected to a gate of the transistor. Charge held in the capacitor element according to total voltage of voltage corresponding to the threshold voltage of the transistor and image signal voltage is once discharged through the transistor, so that variation in current flowing in the transistor or mobility of the transistor can be reduced.