Electrostatic Input Device Reference Updating for Touch Detection
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Solution Overview
Problem
Existing electrostatic input devices erroneously determine that no touch operation is being performed when a finger is stopped while touching the sensor face due to incorrect updating of the reference value.
Innovation Solution
The device includes a control unit that determines proximity states based on a first difference value obtained by subtracting a reference value from a measurement value, calculates a sum difference value, and updates the reference value only when a state of minimal fluctuation continues for a predetermined time, thereby preventing erroneous determinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the reference value is updated continuously to track changes in the sensor environment, then the device can adapt to environmental variations, but the device erroneously determines that no touch operation is being performed when a finger is stopped while touching the sensor face
Solution Approach 1:
The control unit performs preliminary actions by updating the reference value only when specific conditions are met (sum difference value decreases and fluctuation amount is small for a predetermined time or longer). This prevents premature or incorrect updates that would cause erroneous non-proximity determinations while still allowing the reference value to adapt to environmental changes.
Solution Approach 2:
The control unit uses feedback from the measurement values and sum difference values to determine when to update the reference value. By continuously monitoring the fluctuation amount and duration, the system feedback-adjusts the reference value updating process to distinguish between temporary environmental variations and sustained changes, preventing erroneous touch determinations.
2Measurement precision
If the reference value is updated frequently to maintain accuracy, then the device responds better to environmental changes, but the device cannot distinguish between temporary fluctuations and sustained changes
Solution Approach 1:
The control unit performs preliminary verification before updating the reference value by checking whether the sum difference value has decreased and whether the fluctuation amount remains small for a predetermined time or longer. This preliminary action filters out temporary fluctuations and ensures only sustained changes trigger reference value updates, maintaining measurement precision without excessive complexity.
Solution Approach 2:
The control unit dynamically adjusts the reference value updating process based on real-time conditions. When the sum difference value decreases and fluctuation amount is small for a predetermined time, the system dynamically updates the reference value. This dynamic approach allows the system to adapt to environmental changes while maintaining the ability to distinguish between temporary and sustained variations.
3Reliability
If the reference value is updated only when the sum difference value decreases significantly, then the device avoids erroneous updates, but the device cannot promptly adapt to gradual environmental changes
Solution Approach 1:
The control unit performs preliminary monitoring of the sum difference value and fluctuation amount before updating the reference value. By checking whether the sum difference value decreases and the fluctuation amount remains small for a predetermined time or longer, the system prepares to update the reference value at the optimal moment, ensuring both reliability and timely adaptation to environmental changes.
Solution Approach 2:
The control unit continuously monitors the measurement values, sum difference values, and fluctuation amounts to maintain continuous readiness for reference value updates. This continuous monitoring ensures that when environmental changes occur, the system can promptly and accurately update the reference value without delays, balancing reliability with adaptive speed.
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 accurately distinguishes between proximity and non-proximity states, reducing erroneous touch operation detections and ensuring precise control.
Implementation Method 1
a measurement circuit that outputs a measurement value based on a capacitance between each of the plurality of electrostatic sensor electrodes and an indication body
Data Source
AI summary
An electrostatic input device includes electrostatic sensor electrodes, a measurement circuit that outputs a measurement value, a control unit that determines whether a state is a proximity state in which the indication body is close to the sensor electrodes, and a storage unit that stores as a reference value a measurement value in a state in which the indication body is not close to the sensor electrodes, wherein the control unit determines whether a state is a proximity state based on a first difference value obtained by subtracting the reference value from a measurement value, calculates a sum difference value obtained by summing up the first difference values, and when a state in which a fluctuation amount of the sum difference value is smaller than a predetermined value continues for a predetermined time or longer after the sum difference value decreases in the proximity state, updates the reference value.