Keyboard Resistance Sensing to Prevent Ghost Key Detection Errors
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Solution Overview
Problem
Conventional keyboards suffer from the 'ghost key' phenomenon when multiple switches are activated simultaneously, leading to incorrect key detection due to the need for additional diodes, which increases cost.
Innovation Solution
An anti-ghosting keyboard design that utilizes sensing modules with sequentially connected switches and resistors forming an ascending resistance sequence, coupled with a detection and processing unit to determine switch activation status without additional diodes, using a divider resistor and detection module to generate potential level values for key-press signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diodes are added to each switching module to prevent ghost key generation, then the ghost key phenomenon is eliminated, but the overall cost increases due to the increased number of components
Solution Approach 1:
The patent extracts the diode component from each switching module and replaces it with a resistance-based detection mechanism. The sensing resistors are connected in parallel with the switches, and the control unit detects switch activation through voltage changes without requiring diodes, thereby eliminating the harmful factor (ghost key) while reducing device complexity
Solution Approach 2:
The patent changes the detection parameter from current direction (which requires diodes) to resistance value detection. By connecting sensing resistors in parallel with switches and measuring voltage changes at the control unit, the system can identify activated switches through parameter changes in the electrical circuit without needing diodes for current direction control
2Reliability
If diodes are added to each switching module to prevent ghost key generation, then the ghost key phenomenon is eliminated, but the manufacturing cost increases due to additional components
Solution Approach 1:
The patent extracts the diode component from each switching module and replaces it with a resistance-based detection mechanism. The sensing resistors are connected in parallel with the switches, and the control unit detects switch activation through voltage changes without requiring diodes, thereby eliminating the harmful factor (ghost key) while reducing device complexity
Solution Approach 2:
The patent replaces expensive diodes with simpler, cheaper sensing resistors that can be easily integrated into the keyboard circuit. The resistance-based detection method uses standard electronic components that are more cost-effective than diodes, reducing manufacturing costs while maintaining ghost key prevention functionality
3Device complexity
If conventional switching modules are used without additional components, then the device complexity is low, but the ghost key phenomenon occurs when multiple switches are activated simultaneously
Solution Approach 1:
The patent introduces sensing resistors as intermediary components connected in parallel with each switch. These resistors act as mediators that allow the control unit to detect switch activation status through voltage changes without interfering with the switch's primary function, thereby improving key detection accuracy while maintaining simple switching module structure
Solution Approach 2:
The patent implements a feedback mechanism where the control unit continuously monitors voltage changes at the sensing resistors and adjusts its detection logic accordingly. When multiple switches are activated simultaneously, the control unit receives feedback from the voltage division ratios and accurately identifies the activated keys, preventing ghost key generation while keeping the module structure simple
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
Prevents 'ghost key' generation by clearly distinguishing switch activations through unique equivalent resistance values, reducing complexity and cost by eliminating the need for additional diodes.
Implementation Method 1
For each of the sensing modules, resistance values respectively of the N number of sensing resistors form an ascending sequence, and any one of the resistance values in the ascending sequence, except for a first one of the resistance values, is greater than a sum of all of those of the resistance values before the any one of the resistance values
Implementation Method 2
The detection module is configured to obtain a divided voltage value across the divider resistor and to generate, based on the divided voltage value, a potential level value that corresponds to a proportion between the equivalent resistance value of the one of the sensing modules and a resistance value of the divider resistor
Data Source
AI summary
An anti-ghosting keyboard includes a sensing unit, a detection unit, and a processing unit. The sensing unit includes a plurality of sensing modules, each of which includes N number of switches and N number of sensing resistors, where N is a positive integer greater than one. The detection unit includes a divider resistor that is connected in series with one of the sensing modules, and a detection module that is connected to a point of connection between the sensing unit and the divider resistor. The detection module obtains a divided voltage value across the divider resistor and generates a potential level value based on the divided voltage value. The processing unit is electrically connected to the detection module for receiving the potential level value therefrom, and generates a key-press signal that corresponds to the one of the sensing modules based on the potential level value thus received.