Single-Pin Key Detection Circuit Using Resistance Comparison
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Solution Overview
Problem
Conventional key press detecting circuits require multiple pins for each key, leading to increased costs and size when detecting the status of multiple keys.
Innovation Solution
A key press detecting circuit that uses a single pin to apply a constant or variable current to a key module, where the voltage or current is compared with reference values to identify the status of multiple keys, allowing for detection through a single pin connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple pins are used for each key in conventional key press detecting circuits, then the detection accuracy and reliability are maintained, but the costs and size of the key detector chip increase
Solution Approach 1:
The patent merges multiple key detection functions into a single pin interface. The key detector chip uses one pin to detect multiple keys by sequentially applying test signals and measuring equivalent resistance changes, eliminating the need for separate pins for each key while maintaining detection reliability
Solution Approach 2:
The single pin in the key detector chip performs multiple functions: it sequentially connects to different key circuits, applies test signals, measures resistance changes, and identifies multiple key statuses. This multi-functional approach replaces the conventional one-pin-one-key configuration
2Measurement precision
If multiple pins are used for each key in conventional key press detecting circuits, then the detection accuracy is maintained, but the manufacturing costs increase
Solution Approach 1:
The patent combines multiple detection channels into a single pin interface, reducing the number of pins required on the key detector chip. This consolidation lowers manufacturing costs while maintaining detection precision through sequential resistance measurement of each key circuit
3Area of stationary object
If a single pin is used to detect multiple keys, then the costs and size are reduced, but the device complexity increases
Solution Approach 1:
The key detector chip implements periodic action by sequentially cycling through different key circuits using the single pin. The control unit generates periodic test signals that switch between different key connections, allowing the system to measure each key's resistance in turn while maintaining a simple external interface
Solution Approach 2:
The patent introduces a control unit as an intermediary between the single pin and multiple key circuits. This control unit manages the sequential switching and measurement process, coordinating the complex internal operations while presenting a simple single-pin interface to the external key module
4Ease of operation
If multiple pins are used for each key, then the ease of operation is maintained, but the quantity of components increases
Solution Approach 1:
The single pin serves multiple functions by sequentially connecting to different key circuits through internal switching. This multi-functional design reduces the quantity of pins from multiple to one, while the control unit ensures straightforward operation by automatically managing the detection sequence
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
This solution reduces the number of pins needed in the key detector chip, minimizing costs and size, while enabling efficient detection of multiple keys with any resistor arrangement, thereby optimizing resource utilization.
Implementation Method 1
a constant current is provided to apply to a key module through a single pin, to generate a voltage at the single pin that is related to the equivalent resistance of the key module observed from the single pin
Data Source
AI summary
A key press detecting circuit and method detect the status of multiple keys through a single pin. In an embodiment, a constant current is provided to apply to a key module through a single pin, to generate a voltage at the single pin that is related to the equivalent resistance of the key module observed from the single pin, and the voltage of the single pin is compared with a set of reference values to identify the status of the plurality of keys. In another embodiment, a variable current is provided to apply to a key module through a single pin in such a way that the variable current is adjusted to maintain a constant voltage at the single pin, and the variable current is compared with a set of reference values to identify the status of the plurality of keys.