Key Status Detection Using a Calibrated Conversion Circuit
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Solution Overview
Problem
Conventional keyboard apparatuses face challenges in accurately detecting key status due to comparator tolerance drift, leading to misjudgment and increased circuitry resource consumption as the number of keys increases.
Innovation Solution
An electronic apparatus utilizing a conversion circuit with a calibration mechanism, which assists in key status detection by dynamically switching to assist the scan function, reducing the need for calibration in the key control circuit and minimizing re-scan time and frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of keys in the keyboard apparatus increases, then the key detection capability is improved, but the number of sensing lines and comparators increases causing circuit complexity and resource consumption to worsen
Solution Approach 1:
The conversion circuit is designed to perform multiple functions: it serves as an analog-to-digital converter for temperature sensing while also functioning as a key status detection circuit. The same hardware resources are dynamically allocated to different tasks based on system needs, allowing the circuit to handle both temperature monitoring and key detection without requiring separate dedicated circuits for each function.
Solution Approach 2:
The system dynamically switches the conversion circuit between different operating modes using control signals. The circuit can be configured to operate as a temperature sensor ADC or as a key detection circuit based on real-time system requirements. This dynamic reconfiguration allows efficient resource utilization while supporting an increased number of keys without proportionally increasing circuit complexity.
2Speed
If comparators are used to detect key press status, then the detection speed is improved, but comparator tolerance drift during manufacturing causes measurement precision to worsen
Solution Approach 1:
The system implements a two-stage detection process with feedback mechanism. First, a quick scan is performed to identify potentially pressed keys, then a second verification stage confirms the actual key status. This feedback-based approach allows the system to quickly identify candidates while maintaining high accuracy through verification, compensating for comparator tolerance drift without sacrificing detection speed.
Solution Approach 2:
The system performs a preliminary scan of all keys to identify which keys might be pressed, then focuses subsequent detailed detection only on those specific keys. This preliminary action filters out the majority of non-pressed keys early, allowing the system to maintain high detection speed while applying more precise verification only where needed, thus reducing the impact of comparator drift on overall accuracy.
3Measurement precision
If calibration is performed on each comparator to obtain offset for accurate key detection, then the measurement precision is improved, but the circuit resource consumption and complexity worsen
Solution Approach 1:
The conversion circuit serves dual purposes: it acts as an ADC for temperature sensing and as a key detection circuit. By reusing the same calibrated conversion circuit for both temperature monitoring and key detection, the system eliminates the need for separate comparator calibration storage, reducing circuit complexity while maintaining detection accuracy through the verified two-stage detection process.
Data Source
AI summary
An electronic apparatus and a method for detecting status of keys thereof are provided. The electronic apparatus comprises a key module, a key control circuit, a conversion circuit with calibration mechanism and a processor. The key control circuit detects whether any of keys in the key module is pressed. If the detection result is affirmative, the press status of each of the keys is scanned by the key control circuit to obtain a coarse scan result. The conversion circuit with calibration mechanism is configured to perform the other system function of the electronic apparatus. When the processor determines that at least one of the keys is not pressed according the coarse scan result, the conversion circuit with calibration mechanism is switched to assist a re-scan operation of the press status of the at least one of the keys.