Display Device Driving Transistor Compensation via Block Selection
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Solution Overview
Problem
Existing organic EL display devices face complications in compensating for driving transistor characteristic variations, leading to brightness inconsistencies, with current solutions either increasing pixel circuit complexity, prolonging writing time, or requiring external memory.
Innovation Solution
An active matrix-type display device with a data driving unit and scanning driving unit that detects and corrects driving transistor characteristics on a block basis, allowing for efficient compensation without adding transistors to the pixel circuit and eliminating the need for external memory, thereby simplifying the configuration and reducing writing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transistor is added to the pixel circuit for threshold voltage compensation, then compensation for driving transistor variation is achieved, but the pixel circuit configuration becomes complicated
Solution Approach 1:
A detection circuit is introduced as an intermediary component between the pixel circuit and data line. This separate detection circuit performs threshold voltage detection without requiring additional transistors within the pixel circuit itself, thus achieving compensation functionality while maintaining pixel circuit simplicity
Solution Approach 2:
The compensation function is segmented from the pixel circuit and implemented in a separate detection circuit. This separation allows the pixel circuit to remain simple while the detection circuit handles the compensation task externally
2Measurement precision
If threshold voltage detection and data writing are performed sequentially, then detection accuracy is maintained, but the writing time becomes insufficient
Solution Approach 1:
The scanning driving unit implements periodic action by providing a common selection period for block selection followed by a scanning period for sequential scanning. This periodic structure allows detection to occur during the common selection period while writing occurs during the scanning period, ensuring both detection accuracy and sufficient writing time
Solution Approach 2:
The common selection period is placed before the scanning period to perform preliminary block selection and detection. This preliminary action prepares the system by selecting blocks and detecting threshold voltages before the actual data writing begins, ensuring detection accuracy is maintained while optimizing the subsequent writing time
3Measurement precision
If external memory is added for storing compensation information, then compensation accuracy is improved, but the external circuit configuration becomes complicated
Solution Approach 1:
The detection circuit performs self-service by directly detecting threshold voltage characteristics and generating correction values without requiring external memory for storage. The correction values are immediately applied to compensate for driving transistor variations, achieving compensation accuracy while avoiding the complexity of external memory circuits
Data Source
AI summary
A gate driver divides n scanning lines (G1 to Gn) into p blocks (BL1 to BLp), and provides for each block, a common selection period for selecting a whole or a part of k scanning lines included in the block, and a scanning period for sequentially selecting k scanning lines included in the block. A source driver (30) detects a characteristic of a driving transistor via a data line from a pixel circuit (11) corresponding to a scanning line that is being selected in the common selection period, and supplies to the data line a corrected data voltage that has been obtained by correcting the data voltage based on the detected characteristic of the driving transistor. Accordingly, there is provided a display device that can compensate for a characteristic variation of the driving transistor while solving a shortage of writing time.