Capacitive Heater Contact Sensing Under Temperature Variation
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Solution Overview
Problem
Conventional heater devices struggle to accurately determine contact or non-contact with an object due to temperature changes, leading to incorrect determinations and discomfort for users.
Innovation Solution
A heater device with a heat generating portion on an insulating base and electrodes that detect capacitance changes, using a contact determination unit to differentiate between contact and non-contact based on directional capacitance changes and threshold values, while correcting capacitance values to suppress temperature-induced errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitance change is used to detect contact, then contact detection capability is improved, but temperature changes cause false detections
Solution Approach 1:
The patent introduces a temperature detection unit as an intermediary element that monitors temperature changes and provides correction data to the contact determination unit. This mediator allows the system to account for temperature-induced capacitance variations without compromising the primary contact detection function, thereby resolving the contradiction between detection sensitivity and reliability under varying conditions.
Solution Approach 2:
The system dynamically adjusts the capacitance change determination threshold based on detected temperature values. As temperature changes, the threshold is modified to compensate for thermal effects on capacitance, allowing accurate contact detection across different temperature conditions while preventing false positives from temperature-induced capacitance drift.
2Measurement precision
If large capacitance changes are corrected, then measurement accuracy is improved, but computational overflow risk increases
Solution Approach 1:
The contact determination unit applies correction selectively based on the magnitude of capacitance change. When capacitance change exceeds a predetermined threshold, correction is applied; otherwise, the raw value is used directly. This partial action approach corrects only the problematic cases that would cause overflow, maintaining computational stability while still improving accuracy where needed.
Solution Approach 2:
The system creates a corrected copy of the capacitance change value when temperature compensation is needed, rather than modifying the original measurement. This copying mechanism allows the system to work with corrected data for determination purposes while preserving the original measurement data, preventing computational overflow from large corrections while maintaining measurement integrity.
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
Accurately determines object contact or non-contact, reducing user discomfort and heater output adjustments, while preventing computational overflows from large capacitance changes.
Implementation Method 1
a plurality of electrodes which are arranged on the insulating base material and are configured to detect a contact or a non-contact of an object. The heater device further comprises a contact determination unit which determines the contact or the non-contact of the object based on a change in capacitance between the plurality of electrodes.
Data Source
AI summary
A heater device includes a contact determination unit for determining contact or non-contact of an object based on a change in capacitance between a plurality of electrodes. The contact determination unit is configured to determine (i) the contact of the object in response to a determination that the change in capacitance between the plurality of electrodes per predetermined unit time is a change in one direction and equal to or larger than a first determination threshold value. The contact determination unit is configured to determine (ii) the non-contact of the object in response to a determination that the change in capacitance between the plurality of electrodes per predetermined unit time is a change in a direction opposite to the one direction and equal to or larger than a second determination threshold value.