Touch Input Sensing Apparatus Quasi-Differential Clock Synchronization
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Solution Overview
Problem
Touch input sensing apparatuses, such as touchscreens and touchpads, face challenges in detecting the subtle differences in fingerprint ridges and valleys due to limited sensitivity, particularly in recognizing individual fingerprints effectively.
Innovation Solution
A touch input sensing apparatus is designed with a driver that outputs a first clock signal to sensing electrodes and a sensor that senses touch inputs, utilizing a reference signal generator to produce a second clock signal with a higher frequency, phase-delayed between 0 degrees and 180/k degrees, where k is greater than 1, to improve sensitivity and reduce noise by increasing the operating frequency of the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the operating frequency of the sensor is increased to improve sensitivity, then the signal-to-noise ratio is enhanced, but the device complexity increases due to the need for multiple clock signals and phase synchronization
Solution Approach 1:
The patent changes the frequency parameter of the clock signal from a single frequency to multiple frequencies (first clock signal and second clock signal with different frequencies). This parameter change enables the sensor to operate at higher effective frequencies for improved sensitivity while managing noise through frequency multiplication (k times greater), resolving the contradiction between measurement precision and device complexity by systematically organizing the frequency parameters.
Solution Approach 2:
The patent employs periodic clock signals with specific phase relationships (phase delay between 0 and 180/k degrees) to drive the sensing electrodes and sensor. This periodic action with controlled phase differences creates a structured sampling pattern that enhances signal detection while filtering noise, addressing the sensitivity improvement need without requiring overly complex continuous high-frequency operation.
2Object-affected harmful factors
If a higher frequency second clock signal is used to reduce noise, then the signal-to-noise ratio improves, but the manufacturing precision requirements increase for timing synchronization
Solution Approach 1:
The patent defines a specific parameter range for phase delay (0 to 180/k degrees) rather than requiring exact phase alignment. This parameter specification provides a tolerance window that reduces manufacturing precision requirements while still achieving effective noise reduction through the higher frequency second clock signal (k times greater than the first clock signal frequency).
Solution Approach 2:
The patent applies a phase delay that is partial (not complete 180-degree opposition) but sufficient to achieve noise reduction. By using a phase delay within 0 to 180/k degrees with k>1, the system achieves adequate noise filtering without requiring precision synchronization, demonstrating partial action that satisfies the noise reduction goal while relaxing manufacturing constraints.
3Measurement precision
If the frequency ratio k is increased to enhance sensitivity, then touch input detection capability improves, but the loss of time for signal processing increases
Solution Approach 1:
The patent uses periodic clock signals with a defined frequency relationship (second clock signal at k times the frequency of the first clock signal) to balance sensitivity enhancement with processing time management. The periodic nature allows for structured sampling and processing intervals, where higher k values improve fingerprint ridge/valley detection sensitivity while the regular periodic structure enables efficient signal processing at each cycle, mitigating time loss.
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 enhances the signal-to-noise ratio (SNR) and improves touch input sensitivity, allowing for better recognition of fingerprints by increasing the frequency of the second clock signal, which reduces noise and distortion, thereby improving the apparatus's ability to detect touch inputs accurately.
Implementation Method 1
a first electrode connected to the driver and configured to receive the first clock signal, and a second electrode disposed to intersect the first electrode, connected to the sensor, and configured to vary a capacitance according to a touch input on a display or a touchpad
Data Source
AI summary
A touch input sensing apparatus includes a driver configured to output a signal to sensing electrodes, a sensor configured to sense a touch input from the sensing electrodes, and a reference signal generator configured to output a first clock signal to the driver and output a second clock signal to the sensor. The second clock signal frequency is k times greater than a frequency of the first clock signal. The reference signal generator is configured to synchronize the first clock signal with the second clock signal to delay a phase of the second clock signal is delayed from the first clock signal between 0 degrees and 180/k degrees, wherein k is a constant greater than 1.