Touch Screen Scanning Circuit Multiplexing Signal Terminals
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Solution Overview
Problem
The increasing number of receiving-electrode channels in touch screens leads to a higher number of signal input terminals in the touch driving circuit, making wiring formation increasingly difficult and costly.
Innovation Solution
A scanning circuit with a multiplexing circuit that controls the touch driving circuit to receive output signals from multiple receiving-electrode channels through a reduced number of signal input terminals, using transistors and multiplexing sub-circuits to manage signal output and control the reception of signals across multiple time slots during a scanning period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If each column of receiving-electrode channel is electrically connected to one signal input terminal of the touch driving circuit, then the touch position can be determined accurately, but the number of signal input terminals increases with the number of receiving-electrode channels, making wiring formation increasingly difficult and costly
Solution Approach 1:
The patent divides the receiving-electrode channels into multiple groups, where each group is connected to a separate signal input terminal. During each scanning period, only one group of channels is actively scanned through the multiplexing circuit. This segmentation allows the system to handle a large total number of channels (e.g., 18 channels divided into 3 groups of 6) while maintaining a manageable number of signal input terminals (6 terminals instead of 18), thus resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The patent implements periodic scanning by dividing the scanning period into multiple time slots, with each time slot dedicated to scanning a specific group of receiving-electrode channels. The multiplexing circuit switches between different channel groups in a periodic manner. This periodic action enables the system to sequentially scan all channels over multiple time slots while using fewer signal input terminals, maintaining touch position determination accuracy without requiring a proportional increase in terminal count
2Adaptability or versatility
If more receiving-electrode channels are formed on the touch panel to improve touch detection coverage, then the touch detection capability is enhanced, but the number of signal input terminals in the touch driving circuit increases, leading to higher production costs
Solution Approach 1:
The patent segments the receiving-electrode channels into multiple groups that can be scanned sequentially. By dividing channels into groups (e.g., 18 channels into 3 groups), the system achieves comprehensive touch detection coverage across the entire touch panel while requiring only a fraction of signal input terminals compared to direct one-to-one connection. This segmentation strategy enables enhanced touch detection capability without proportionally increasing production complexity and cost
Solution Approach 2:
The multiplexing circuit serves multiple functions: it groups channels, switches between groups, and enables sequential scanning. This multi-functional component allows a small number of signal input terminals to handle a large number of channels, making the touch driving circuit more cost-effective while maintaining comprehensive touch detection coverage across the entire panel surface
Data Source
AI summary
The present disclosure discloses a scanning circuit for touch screen, touch screen and touch control method. The canning circuit for touch screen includes: a multiplexing circuit and a touch driving circuit coupled to the same, the touch driving circuit includes m signal input terminals, each of which is coupled to n receiving-electrode channels, and in an ith time slot of a current scanning period, the multiplexing circuit controls the touch driving circuit to receive, through the m signal input terminals, output signals from m receiving-electrode channels, and determines a touch position according to an emitting-electrode channel corresponding to the current scanning period and the output signals of the m receiving-electrode channels, the current scanning period includes n time slots, i=1, 2, . . . n, and the output signals of the m receiving-electrode channels received by the touch driving circuit in each time slot are different.