Touch Panel Control Device Staggered Sensing Lines
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Solution Overview
Problem
The existing touch panels face a significant time delay in stabilizing induced voltages due to resistance and parasitic capacitors, which affects the operating frequency and detection time, especially as the panel size increases, making it necessary to develop a control device that can enhance the detection efficiency.
Innovation Solution
A control device comprising a clock generation circuit, selection module, drive signal generation circuit, digital to analog conversion module, capacitors, and a differential detection circuit, which generates specific clock signals and drive voltages to optimize the scanning sequence and voltage levels, allowing for faster detection of touch positions by minimizing the RC time delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the touch panel size is increased, then the coverage area is improved, but the RC time delay increases causing slower voltage stabilization
Solution Approach 1:
The patent applies preliminary action by pre-charging or pre-discharging the sensing lines through the drive signal generation circuit before the actual measurement phase. This preliminary action reduces the RC time delay effect during the measurement phase, allowing faster voltage stabilization even in large-sized touch panels.
Solution Approach 2:
The patent uses periodic drive signals with specific frequencies to periodically charge and discharge the sensing lines. This periodic action helps to overcome the RC time delay by creating predictable voltage patterns that can be measured more quickly, thereby reducing the overall voltage stabilization time in large touch panels.
2Productivity
If the operating frequency of the drive signal is increased, then the detection speed is improved, but the voltage stabilization time increases due to RC time delay
Solution Approach 1:
The patent dynamically adjusts the drive signal frequency and timing based on the scanning phase. During the pre-charge phase, a different frequency is used compared to the measurement phase. This dynamic adjustment allows the system to optimize between detection speed and voltage stabilization time, achieving high productivity without excessive stabilization delays.
Solution Approach 2:
By performing preliminary charging/discharging operations at optimized frequencies before the actual measurement, the patent reduces the effective stabilization time during the critical measurement phase. This allows higher operating frequencies to be used without proportionally increasing the voltage stabilization time.
3Measurement precision
If the sensing lines are arranged in a staggered manner, then the sensing accuracy is improved, but the number of parasitic capacitors increases causing longer stabilization time
Solution Approach 1:
The patent segments the sensing operation into distinct phases: pre-charge phase and measurement phase. During the pre-charge phase, the drive signal is applied to charge the parasitic capacitors created by the staggered sensing line arrangement. During the measurement phase, only the essential measurement signals are used. This segmentation allows the system to tolerate more parasitic capacitors while maintaining fast measurement speeds and high accuracy.
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
The proposed control device significantly increases the sensing speed of touch panels by reducing the time required for voltage stabilization, enabling faster detection and improved performance even in larger touch panels.
Implementation Method 1
The first capacitor is coupled between the selection module and a differential detection circuit. Two parallel surfaces of the first capacitor subject to two voltage levels, V1 and V3, respectively. Therefore, the first capacitor is configured to manifest a variation of the third voltage V3 on the first voltage V1. The second capacitor is coupled between the selection module and the differential detection circuit. Two parallel surfaces of the second capacitor subject to two voltage levels, V2 and V4, respectively. Therefore, the second capacitor is configured to manifest a variation of the fourth voltage V4 on the second voltage V2.
Implementation Method 2
In addition to the capacitive touch panel, other touch panels based on different sensing principles include resistive touch panels, optical touch panels and surface acoustic wave touch screen panels. The touch panel includes a plurality of first direction sensing lines and a plurality of second direction sensing lines... a number of parasitic capacitors (not shown) are formed between every X-directional sensing line and the ground.
Implementation Method 3
In the sensing grid, a plurality of mutual capacitors (not shown) are formed between every X-directional sensing line and every Y-directional sensing line. During operation, a drive signal (usually a square-wave signal) is input to the X-directional sensing lines or the Y-directional sensing lines. As a result of a coupling effect of the mutual capacitors, a plurality of induced voltages are generated on corresponding Y-directional sensing lines or X-directional sensing lines.
Data Source
AI summary
A touch panel includes a plurality of X-directional sensing lines and a plurality of Y-directional sensing lines. The X-directional sensing lines and the Y-directional sensing lines are arranged in a staggered manner. The control device includes a clock generation circuit, a selection module, a drive signal generation circuit, a digital to analog conversion module, first and second capacitors and a differential detection circuit. The X-directional sensing lines and Y-directional sensing lines on the touch panel operate according to a predetermined scanning sequence. According to the control device and the predetermined scanning sequence of the present invention, the sensing speed of the touch panel can be improved.