Touch Input Readout Circuit With Phase Compensation for RC Delay
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Solution Overview
Problem
Existing touch screens face challenges in accurately detecting user inputs and minimizing erroneous detections, particularly in ensuring desired sensitivity and reducing false capacitance due to varying RC delays in transmit electrodes.
Innovation Solution
The implementation of an input sensing device with a readout circuit that includes a phase adjustment circuit, which outputs a phase adjustment signal based on the delay characteristic of the transmit electrode, to adjust the phase of the transmission signal and minimize false capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase adjustment is applied to compensate for RC delay variations in transmit electrodes, then measurement precision of user inputs is improved, but device complexity increases due to additional phase adjustment circuitry
Solution Approach 1:
The patent applies parameter changes by adjusting the phase of transmission signals dynamically to compensate for RC delay variations in different transmit electrodes. The phase adjustment circuit modifies the phase parameter of each transmission signal based on measured delay characteristics, ensuring synchronized signal arrival at receive electrodes and eliminating false capacitance variations.
Solution Approach 2:
The patent implements feedback by measuring the actual phase delay of each transmit electrode and using this information to adjust the transmission signal phase. The system continuously monitors delay characteristics and applies compensatory phase shifts, creating a closed-loop control mechanism that maintains detection accuracy despite manufacturing variations.
2Area of stationary object
If multiple transmit electrodes with different RC delays are used to increase sensing coverage, then area of sensing device is improved, but measurement precision deteriorates due to false capacitance variations
Solution Approach 1:
The patent applies local quality by customizing the phase adjustment for each individual transmit electrode based on its specific RC delay characteristics. Each transmit electrode receives a tailored phase correction tailored to its local electrical properties, ensuring that signals from different locations in the expanded sensing area arrive at receive electrodes simultaneously without introducing false capacitance variations.
3Measurement precision
If phase adjustment circuit is added to each transmit electrode to compensate for delay variations, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies universality by designing a phase adjustment circuit that serves multiple functions: it measures RC delay characteristics, calculates required phase corrections, and applies phase shifts to multiple transmit electrodes. This multi-functional approach consolidates what could be multiple separate circuits into a single integrated unit, reducing overall manufacturing complexity and cost while maintaining detection precision.
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 solution enhances the accuracy of user input detection by minimizing false capacitance and ensuring consistent phase alignment across transmission signals, thereby improving the overall sensitivity and reliability of the touch screen.
Implementation Method 1
a phase adjustment circuit that outputs a phase adjustment signal corresponding to a delay characteristic of the transmit electrode; and a transmitter that outputs a transmission signal, a phase of which is adjusted in response to the phase adjustment signal
Implementation Method 2
an input sensor including a transmit electrode and a receive electrode
Data Source
AI summary
An input sensing device of a display device, which includes an input sensor including a transmit electrode and a receive electrode and a readout circuit that drives the input sensor. The readout circuit includes a phase adjustment circuit that outputs a phase adjustment signal corresponding to a delay characteristic of the transmit electrode and a transmitter that outputs a transmission signal, a phase of which is adjusted in response to the phase adjustment signal, to the transmit electrode.