Key Matrix Scan Switching for Low-Power Accurate Key Detection
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Solution Overview
Problem
Existing key input devices face challenges in reducing the number of circuit components while maintaining advanced functionality and power consumption efficiency, particularly in determining operated keys with a minimal number of diodes, and struggle with restarting key scans after being stopped.
Innovation Solution
A key input device design that includes a control section capable of receiving a key return signal as an interrupt signal to switch from a standby mode to a normal mode, performing a key scan operation to determine operated keys, and utilizing a key matrix section with multiple key switches connected via signal line groups to supply key return signals, reducing the need for multiple diodes and allowing efficient key scan operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple diodes are used to determine operated keys in simultaneous key scan, then key determination accuracy is improved, but device complexity increases
Solution Approach 1:
The patent extracts the key determination function from the simultaneous scan process and implements it sequentially. Instead of using multiple diodes to parallel-determine multiple keys at once, the system scans keys one by one in sequence, eliminating the need for multiple determination diodes while maintaining accurate key detection
Solution Approach 2:
The patent dynamically switches the control section between standby mode and normal mode based on interrupt signals. The key scan operation is performed sequentially in normal mode, with the system dynamically adapting its operation state to reduce circuit complexity while maintaining functional accuracy
2Speed
If key scan operation is continuously performed, then key response speed is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic key scan operations instead of continuous scanning. The control section alternates between standby mode (low power) and normal mode (active scanning), performing key scans at regular intervals triggered by interrupt signals. This periodic action maintains key response capability while significantly reducing overall power consumption during idle periods
Data Source
AI summary
In a key input device, a control section is configured to receives a key return signal as an interrupt signal in a standby mode, to set a normal mode in response to the interrupt signal, and to perform a key scan operation in the normal mode to determine an operated key. A key matrix section having a plurality of keys and configured to supply the key return signal to the control section in response to an operation to the operated key of the plurality of keys.