Input Sensing Device Touch Coordinate Accuracy
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Solution Overview
Problem
Current display devices face challenges in accurately sensing user inputs, particularly in distinguishing between touch sensing and compensation periods, which affects the precision of touch coordinate calculation.
Innovation Solution
The implementation of an input sensing device with a readout circuit that includes a switching circuit, first and second output circuits, and transmission and reception electrodes, which transfers signals during touch sensing and compensation periods, and mixes signals with in-phase and quadrature phase carriers to enhance sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single reception electrode is used for both touch sensing and compensation, then device complexity is reduced, but measurement precision deteriorates due to inability to distinguish between touch sensing and compensation periods
Solution Approach 1:
The reception electrode is divided into two separate electrodes: a first reception electrode for touch sensing and a second reception electrode for compensation. This segmentation allows independent optimization of each electrode's function, enabling accurate distinction between touch sensing signals and compensation signals, thereby resolving the measurement precision issue while maintaining manageable device complexity
Solution Approach 2:
A switching circuit is introduced as an intermediary component that selectively connects either the first reception electrode or the second reception electrode to the readout circuit during different time periods. This intermediary mechanism enables precise control over which electrode is active during touch sensing versus compensation periods, solving the fundamental problem of signal differentiation
2Speed
If touch sensing and compensation are performed simultaneously using the same electrode, then operation speed is improved, but measurement precision deteriorates due to signal interference
Solution Approach 1:
The system employs periodic time-division multiplexing where the first reception electrode and second reception electrode are activated in alternating time periods. During touch sensing periods, the first electrode is active while the second is inactive, and vice versa during compensation periods. This periodic switching eliminates signal interference while maintaining high operation speed through efficient time management
Solution Approach 2:
The switching circuit dynamically changes its connection state based on the operational phase (touch sensing or compensation), enabling the system to adapt its configuration in real-time. This dynamic switching allows optimal performance for each specific operation mode without the compromises required by static configurations
3Measurement precision
If separate reception electrodes are used for touch sensing and compensation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The switching circuit serves multiple functions: it connects the first reception electrode during touch sensing periods, connects the second reception electrode during compensation periods, and manages the timing coordination between different operational phases. By consolidating these multiple functions into a single multi-functional component, the design achieves high measurement precision without proportionally increasing overall device complexity
Data Source
AI summary
An input sensing device includes: an input sensor including a transmission electrode, a first reception electrode, and a second reception electrode; and a readout circuit configured to provide a transmit signal to the transmission electrode, to receive a first receive signal from the first reception electrode, and to receive a second receive signal from the second reception electrode, wherein the readout circuit includes: a switching circuit configured to transfer the first receive signal and the second receive signal to a first node and a second node, respectively, during a touch sensing period and to transfer one of the first receive signal and the second receive signal to the first node and the second node during a compensation period; a first output circuit configured to convert a signal of the first node into a first sensing signal; and a second output circuit configured to convert a signal of the second node into a second sensing signal.