Capacitive Keyboard Button Sensing for Multi-State Press Detection
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Solution Overview
Problem
Existing electronic buttons, particularly in keyboards, lack the ability to detect multiple states of button presses and object proximity effectively, leading to limitations in functionality and accuracy, such as distinguishing between accidental and purposeful presses, and requiring additional hardware like diodes for simultaneous key press detection.
Innovation Solution
A multi-state capacitive button system that uses a matrix of electrode tracks and capacitive sensing to detect the extent of button depression and object proximity, combining capacitive and mechanical sensing methods to provide detailed state information without the need for diodes, enabling improved touch and proximity sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional mechanical keyboard sensing methods are used, then button press detection is achieved, but the ability to detect multiple states and object proximity is limited
Solution Approach 1:
The patent combines capacitive sensing and mechanical sensing methods into a single keyboard system. The capacitive sensor detects object proximity and button depression extent, while the mechanical sensor detects actual key press registration. This merging allows the system to achieve both accurate multi-state detection and reliable button press detection without requiring separate systems.
Solution Approach 2:
The capacitive sensor serves multiple functions: detecting object proximity, determining button depression extent, and providing data for distinguishing accidental versus purposeful presses. This multi-functionality enables a single sensing mechanism to handle multiple detection tasks that would otherwise require separate hardware components.
2Reliability
If diodes are added to facilitate simultaneous key press detection, then sensing capability is improved, but device complexity increases
Solution Approach 1:
The patent replaces the need for diodes (electronic components) with capacitive sensing technology. The capacitive sensor can detect simultaneous key presses by measuring capacitance changes across multiple keys independently, eliminating the requirement for diodes to prevent signal interference in traditional mechanical keyboard matrices.
Solution Approach 2:
The capacitive sensor acts as an intermediary between the user's fingers and the mechanical switches. By detecting capacitance changes caused by finger proximity and contact, the system can determine which keys are pressed simultaneously without the electrical interference that would normally require diodes to manage.
3Adaptability or versatility
If capacitive sensing is used to detect object proximity and button depression, then multi-state detection is enabled, but hardware complexity increases
Solution Approach 1:
The capacitive sensor array serves multiple detection purposes: proximity detection, depression extent measurement, and simultaneous key press detection. This single component performs multiple functions that would otherwise require separate sensors, actually reducing overall system complexity despite the advanced sensing capability.
Solution Approach 2:
The capacitive sensing system automatically provides multi-state detection information without requiring additional processing hardware or complex configuration. The capacitance measurements naturally provide data about proximity, contact, and depression extent, allowing the system to self-determine button states based on the physical properties of the interaction.
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
Enables accurate detection of button states, reduces hardware requirements, and enhances keyboard functionality by allowing simultaneous key press detection and distinguishing between different objects, improving user interaction and device responsiveness.
Implementation Method 1
The conductor between the button and the sensor may experience capacitive coupling with the underlying sensor when voltage is applied to a portion of the sensor. The conductor may in turn capacitively couple with an electrically isolating material forming the button.
Implementation Method 2
pressing the button may cause the conductor to come into contact with the sensor, which may create a galvanic connection between two electrode tracks of the sensor
Data Source
AI summary
In certain embodiments, a method includes applying voltage to a sensor that includes first and second electrode tracks, the sensor proximate to a conductor depressible relative to the sensor and located between a button and the sensor. The conductor can capacitively couple with a capacitive node formed by the tracks, and the button can capacitively couple with an object. A value of a capacitance at the node is measured, the capacitance reflecting an amount of capacitive coupling between the conductor and the node. In response to the value meeting a first condition, a first button state is detected, indicating the object is within a detectable distance of and not in contact with the button. In response to the value meeting a second condition, a second button state is detected, indicating the object is in contact with the button and the conductor is not in contact with the sensor.