Touch Detecting Circuit Calibration Capacitor Integration
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Solution Overview
Problem
Existing touch detecting circuits face challenges in integrating calibration capacitors with capacitance values similar to sensing capacitors at non-touch states, making it difficult to achieve high detection sensitivity and requiring external mounting, which increases the mounting area and complexity.
Innovation Solution
A touch detecting circuit configuration that includes a charging circuit, a detecting circuit, and a calibration circuit with a calibration capacitor, where the calibration capacitor is charged and discharged in specific periods to measure the capacitance value changes, allowing for high detection sensitivity using a calibration capacitor with a small capacitance value, enabling integration into a semiconductor integrated circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a calibration capacitor with capacitance value similar to sensing capacitor at non-touch state is used, then detection sensitivity is improved, but mounting area and device complexity increase due to external mounting requirement
Solution Approach 1:
The patent merges the calibration capacitor into the semiconductor integrated circuit chip, combining functions that were previously separated. The calibration capacitor is formed on the same chip as the touch detecting circuit, eliminating the need for external mounting and reducing device complexity while maintaining detection sensitivity.
Solution Approach 2:
The calibration capacitor is nested within the semiconductor integrated circuit structure, placed in an unused region of the chip. This nesting approach allows the calibration capacitor to be integrated without increasing the overall device footprint or mounting complexity.
2Measurement precision
If a calibration capacitor with capacitance value similar to sensing capacitor at non-touch state is used, then detection sensitivity is improved, but the area required for integration increases
Solution Approach 1:
The patent applies local quality by utilizing an unused region or idle area within the semiconductor chip for placing the calibration capacitor. This approach ensures that the calibration capacitor occupies only a localized area that would otherwise be empty, avoiding increase in overall integration area while maintaining the required capacitance value for sensitive detection.
3Measurement precision
If charge is discharged completely during calibration period, then calibration accuracy is improved, but charge available for detection in subsequent periods is reduced
Solution Approach 1:
The patent applies preliminary action by completely discharging the calibration capacitor during the calibration period to ensure accurate calibration. After calibration, the capacitor is recharged in preparation for the next detection cycle. This periodic complete discharge and recharge ensures calibration accuracy while maintaining sufficient charge availability for subsequent detection 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 allows for high detection sensitivity by using a small capacitance value calibration capacitor, reducing the area required for integration and simplifying the mounting process, while maintaining accurate touch and non-touch detection.
Implementation Method 1
a calibration capacitor that is coupled to the terminal... The calibration capacitor is configured to be charged by a first portion of electric charge that is discharged from the sensing capacitor
Data Source
AI summary
A touch detecting circuit includes a discharging circuit, a detecting circuit, and a calibration circuit that is configured with a calibration capacitor connected to a terminal and a current source which is connected to the terminal and can be controlled so as to be on and off, that can be connected via the terminal to a sensing capacitor which is disposed on a touch panel, is provided. In the beginning, the sensing capacitor is charged to a predetermined voltage by the charging circuit, thereafter, in a process of discharging, a portion of charge amount that is discharged is used to charge the calibration capacitor, and another portion is discharged via the current source, and the rest is input to the detecting circuit. The detecting circuit measures the charge amount that is input.