Input Device Electrostatic Capacitance Reset for Temperature Errors
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Solution Overview
Problem
Existing electrostatic capacitance sensors face erroneous object detection due to temperature changes, especially when an object is close to the detection surface, as they rely on base value differences that are not updated during object proximity, leading to potential misinterpretation of object presence.
Innovation Solution
An input device with a sensor unit, change amount calculation unit, determination unit, and reset unit that calculates temporal changes in electrostatic capacitance and performs reset processing when a palm operation is not determined and a grip operation is determined for a predetermined time, with peak values exceeding a threshold, to differentiate between intended and unintended object presence and correct for temperature-induced errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base value is not updated during object proximity to avoid erroneous detection, then detection stability is improved, but temperature-induced errors accumulate over time
Solution Approach 1:
The patent implements dynamic base value updating by transitioning from a static base value (not updated during proximity) to a dynamic base value that is continuously updated even when objects are nearby. This allows the system to adapt to temperature changes in real-time while maintaining detection stability through the continuous tracking of baseline capacitance values.
Solution Approach 2:
The patent changes the parameter of base value update timing from 'only when no object is present' to 'continuously during all states including object proximity'. This parameter change enables the system to compensate for temperature drift by continuously adjusting the base value regardless of object presence, thereby maintaining measurement precision under varying thermal conditions.
2Measurement precision
If the base value is continuously updated to compensate for temperature changes, then measurement precision is improved, but erroneous detection of object presence increases
Solution Approach 1:
The patent applies different update strategies to different portions of the detection period. During normal operation, the base value is updated continuously for temperature compensation. However, when specific update conditions are met (such as when capacitance change exceeds a threshold or during calibrated periods), the update behavior is adjusted to prevent erroneous detection. This local differentiation of update quality resolves the contradiction between continuous compensation and detection stability.
3Measurement precision
If reset processing is performed frequently to correct temperature errors, then measurement precision is improved, but system response time to valid operations is delayed
Solution Approach 1:
The patent implements partial reset processing by performing base value updates only when necessary conditions are met, rather than resetting continuously or excessively. The update is triggered by specific conditions such as temperature drift thresholds or time-based intervals, providing just enough compensation to maintain precision without causing delays in operation recognition. This partial action approach balances precision correction with timely response to valid user operations.
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
The solution effectively suppresses erroneous determinations caused by temperature changes by resetting the base value and determining operations accurately, even in environments with significant temperature fluctuations, ensuring reliable object detection.
Implementation Method 1
a sensor unit that detects an electrostatic capacitance that changes according to a proximity degree of an object with respect to a detection surface
Data Source
AI summary
An input device includes a sensor unit, a processing unit, a storage unit, and an interface unit. The processing unit includes: a change amount calculating section for calculating the temporal change amount of the electrostatic capacitance that is detected by the sensor unit and that changes according to the proximity degree of an object with respect to a detection surface; a determination section for determining a touch operation corresponding to an operation on the detection surface using a fingertip, a palm operation corresponding to an operation on the detection surface using a palm, and a grip operation corresponding to an operation on a conductor portion, based on the calculated change amount; and a reset section for performing reset processing in a case where the duration of a state, in which a palm operation is not determined and a grip operation is determined, is a first predetermined time or more.