Cascaded Scan Lines with Diodes for Touch Panel Driving
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Solution Overview
Problem
The increasing size of touch panels requires more driving lines, leading to higher production costs, and existing technologies have not effectively optimized the design of driving circuits in touch devices to reduce this complexity while maintaining accurate touch point determination.
Innovation Solution
The touch device design incorporates cascaded scan lines with diodes and interlaced sense lines, where a controller generates scan and detection signals to determine touch points by managing voltages across nodes, allowing for reduced driving lines and efficient touch point location detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the touch panel size increases, then the coverage area is improved, but the number of driving lines increases leading to higher production cost
Solution Approach 1:
Multiple scan lines are merged into a single cascaded structure where one scan line is sequentially connected to multiple sense lines through diodes. This combining approach reduces the total number of independent driving lines needed while maintaining the ability to address all touch points on the panel.
Solution Approach 2:
The scan lines are divided into multiple cascaded segments, each segment being sequentially activated through diode switching. This segmentation allows the system to control multiple scan lines using a reduced set of driving signals, thereby reducing the overall complexity of the driving circuit.
2Measurement precision
If more driving lines are used to maintain accurate touch point determination, then the measurement precision is improved, but the production cost increases
Solution Approach 1:
Diodes are introduced as intermediary components between scan lines and sense lines. These diodes enable selective electrical connection and isolation, allowing accurate touch point determination through capacitance measurement while using fewer driving lines. The diodes act as switches that mediate the connection between the reduced driving circuit and the full touch panel matrix.
Solution Approach 2:
The cascaded scan line structure with diodes enables self-selective addressing of touch points. When a specific scan line is activated, the diodes automatically route the signal to the appropriate sense lines, eliminating the need for complex external switching circuitry and maintaining measurement precision with simplified driving.
3Device complexity
If the number of scan lines is reduced to lower production cost, then the device complexity is improved, but the productivity of touch point detection may be affected
Solution Approach 1:
The cascaded scan lines are activated in periodic sequential order through the diode network. This periodic activation allows the system to cycle through all scan lines using a reduced set of driving signals, maintaining high touch point detection productivity while using fewer physical driving lines. The sequential periodic scanning ensures complete coverage of the touch panel.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces the number of driving lines needed, lowering production costs while enabling rapid and accurate determination of touch points on the touch panel.
Implementation Method 1
The first scan line is cascaded with a first diode. The second scan line is cascaded with a second diode.
Implementation Method 2
The sense circuit detects a capacitance of the sense line according to a detection signal to generate a receive signal.
Data Source
AI summary
A touch device includes a touch panel, a driving circuit, a sensing circuit, and a controller. The touch panel includes a first scan line cascaded with a first diode, a second scan line cascaded with a second diode, and a sense line interlaced with the first scan line and a second scan line. The first scan line and the second scan line are cascaded between a first node and a second node. The driving circuit generates a scan voltage across the first node and the second node according to a scan signal. The sensing circuit detects a capacitance of the sense line according to a detection signal to generate a receive signal. The controller generates the scan signal and the sense signal and determines the location of a touch point on the touch panel according to the scan voltage and the receive signal.