Dummy Unit Register Circuit for Scanning Line Drive Restart
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Solution Overview
Problem
In liquid crystal display devices with in-cell type touch detection, the drive of scanning lines cannot be restarted due to current leakage during the temporary stop period, leading to interrupted display operations.
Innovation Solution
A dummy unit register circuit is introduced between the unit register circuit that drives the scanning line before the scan stop period and the one that drives it after the stop, which continues to output the scanning signal to the subsequent stage, preventing voltage leaks and allowing for seamless restart of scanning line drive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the scanning line drive is temporarily stopped for touch detection operation, then the touch detection function can be executed, but the scanning line drive cannot be restarted due to current leakage from the single-channel transistor
Solution Approach 1:
A dummy unit register circuit is introduced as an intermediary between the unit register circuit that drives the scanning line before the scan stop period and the unit register circuit that drives it after the stop. This dummy circuit receives the scanning signal from the previous stage and continuously outputs it to the subsequent stage, preventing voltage leakage and enabling seamless restart of scanning line drive after touch detection operation.
Solution Approach 2:
The scanning line driver is segmented into multiple unit register circuits, with a dummy unit register circuit inserted specifically at the boundary between pre-stop and post-stop stages. This segmentation allows the dummy circuit to isolate and prevent current leakage in the critical transition zone while maintaining normal operation in other segments.
2Device complexity
If a single-channel transistor is used in the scanning line driver, then the device structure is simplified, but current leakage occurs during the temporary stop period preventing drive restart
Solution Approach 1:
The dummy unit register circuit acts as a mediator that bridges the gap created by using simple single-channel transistors. It compensates for the inability of single-channel transistors to maintain voltage during stop periods by continuously regenerating and outputting the scanning signal, thus enabling drive restart without requiring complex transistor structures throughout the entire circuit.
Solution Approach 2:
Instead of making the entire scanning line driver complex, the invention applies a specialized dummy unit register circuit only at the critical location where drive restart is needed. This local enhancement maintains simplicity in most of the circuit while providing the necessary functionality at the specific point of contradiction.
Data Source
AI summary
According to one embodiment, a display device equipped with a touch detection function includes scanning lines, and series-connected unit register circuits, wherein a touch detection operation is performed in a scan stop period, each of the unit register circuits is composed of single-channel transistors, holds and outputs a scanning signal when a voltage leak of a held signal is equal to or lower than a predetermined value, a dummy unit register circuit is provided between a previous unit register circuit which drives a last scanning line before start of the scan stop period and a subsequent unit register circuit which drives a first scanning line after end of the scan stop period, and the dummy unit register circuit continues outputting the scanning signal to the subsequent unit register circuit during the scan stop period.