Capacitance and Light Sensing for Contact Position
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing contact detection methods in electronic apparatuses face challenges in accurately determining the contact position of a target object, with electrostatic capacitance methods often incorrectly identifying contact areas as too wide and optical methods incorrectly detecting contact without actual contact.
Innovation Solution
A method combining capacitance sensing circuits for initial contact detection and light sensing circuits for precise contact position determination, where capacitance sensing is used until contact is confirmed and then switched to light sensing for accurate position determination, reducing power consumption by scanning circuits sequentially rather than simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrostatic capacitance sensing is used to detect contact, then contact detection sensitivity is improved, but contact position measurement precision deteriorates
Solution Approach 1:
The patent divides the contact detection process into two separate stages: first using capacitance sensing circuits to detect whether contact has occurred, then using light sensing circuits to determine the precise contact position. This segmentation allows each sensing system to be optimized for its specific function, resolving the contradiction between detection sensitivity and position precision.
Solution Approach 2:
The patent dynamically switches between different sensing modes based on contact state. When contact is detected by the capacitance sensing circuit, the system transitions to using the light sensing circuit for position determination. This dynamic adaptation allows the system to leverage the strengths of each sensing type at the appropriate moment.
2Measurement precision
If optical sensing is used to determine contact position, then position measurement precision is improved, but contact detection reliability deteriorates
Solution Approach 1:
The patent separates the contact detection function from the position measurement function. The capacitance sensing circuit is dedicated to reliable contact detection, while the light sensing circuit is dedicated to precise position measurement. This functional segmentation resolves the contradiction by assigning each task to the most suitable sensing technology.
Solution Approach 2:
The capacitance sensing circuit acts as an intermediary that triggers the switch to optical sensing. It detects the contact event first, then enables the light sensing circuit to take over for position determination, ensuring that optical sensing is only activated when contact has been reliably confirmed.
3Speed
If both capacitance sensing circuits and light sensing circuits are scanned simultaneously, then contact detection speed is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic scanning where capacitance sensing circuits are scanned first to detect contact, and only after contact is detected are the light sensing circuits scanned for position determination. This periodic, sequential action reduces power consumption compared to continuous simultaneous scanning, while maintaining fast response through the staged approach.
Solution Approach 2:
The capacitance sensing is performed as a preliminary action before light sensing. By first detecting contact presence through low-power capacitance sensing, the system prepares the condition for subsequent position measurement, avoiding unnecessary activation of higher-power optical systems when no contact is present.
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 enables high-accuracy contact position detection while minimizing power consumption by leveraging the strengths of both electrostatic capacitance and optical methods, preventing false positives and negatives in contact detection.
Implementation Method 1
measuring changes in electrostatic capacitance formed by a liquid crystal that is pinched by two electrodes facing each other
Implementation Method 2
measures light intensities of incident light and outputs light measuring signals
Data Source
AI summary
A method of determining a contact position in an electronic apparatus including capacitance sensing circuits that output capacitance measuring signals and light sensing circuits that output light measuring signals includes acquiring the capacitance measuring signals by sequentially scanning the capacitance sensing circuits, determining whether a target object is in contact with a contact surface based on the acquired capacitance measuring signals, acquiring the light measuring signals by sequentially scanning the light sensing circuits after the target object is determined to be in contact with the contact surface, and determining a position of the contact surface, with which the target object is in contact, based on the acquired light measuring signals. The acquiring of the capacitance measuring signals and the determining of whether the target object is in contact with the contact surface are repeated until the target object is determined to be in contact with the contact surface.