Keyboard Key Detection Using Two-Stage Scan and Drift Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional keyboard apparatuses face issues with misjudgment of key press status due to comparator drifts and require calibration, leading to increased circuitry resources and slower detection speeds, especially as the number of keys increases.
Innovation Solution
A keyboard apparatus with a key module and controller that employs two-stage detection, using first and second lines to drive and sense keys, allowing parallel detection and coarse scanning to quickly determine key press status, with a comparison circuit without calibration in the first stage and a calibrated circuit in the second stage for accurate determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration is performed on each comparator to obtain offset for precise key detection, then measurement precision is improved, but device complexity increases due to additional circuitry resources required to store offsets
Solution Approach 1:
The patent segments the detection process into two distinct stages: a first detection stage using multiple comparators for parallel comparison, and a second detection stage using a single calibrated comparator for sequential verification. This segmentation allows the system to achieve high measurement precision through calibration while reducing device complexity by limiting the number of calibrated comparators to just one, rather than calibrating all comparators.
Solution Approach 2:
The patent performs preliminary calibration on a single comparator in advance, storing its offset value. This pre-calibrated comparator is then used in the second detection stage to verify and correct results from the first stage. This preliminary action eliminates the need to calibrate every comparator, thereby reducing device complexity while maintaining measurement precision.
2Device complexity
If only one calibrated comparator is used to sequentially perform comparison on sensing lines, then device complexity is reduced, but productivity decreases due to slower detection speed
Solution Approach 1:
The detection process is segmented into two stages with different purposes: the first stage uses multiple comparators operating in parallel to quickly screen all sensing lines, providing high productivity; the second stage uses a single calibrated comparator sequentially to verify results and eliminate ghost keys, ensuring accuracy. This segmentation allows the system to achieve both high detection speed and low device complexity.
Solution Approach 2:
The patent maintains continuous useful action by having the first detection stage continuously monitor all sensing lines in parallel while the second stage continuously verifies results. This dual-stage continuous operation ensures that detection speed is maintained through parallel processing while accuracy is preserved through sequential verification, achieving both high productivity and low device complexity.
3Productivity
If multiple comparators are used to concurrently perform comparison on all sensing lines, then productivity is improved through parallel processing, but measurement precision deteriorates due to comparator drifts causing misjudgment
Solution Approach 1:
The patent implements feedback by using the results from the first detection stage as input for the second detection stage. The calibrated comparator in the second stage verifies and corrects results from the first stage, providing feedback that eliminates misjudgments caused by comparator drift. This feedback mechanism maintains measurement precision while preserving the high productivity achieved through parallel processing in the first stage.
Solution Approach 2:
The patent performs preliminary calibration on one comparator and uses it in the second stage to verify results from the first stage. This preliminary calibration action compensates for comparator drifts affecting multiple comparators in the first stage, thereby maintaining measurement precision while preserving the high detection speed achieved through parallel processing.
Data Source
AI summary
A keyboard apparatus and a detection method for status of keys thereof are provided. The detection method includes the following steps. First lines of a key module in the keyboard apparatus are driven to a first potential. Whether any key on each of second lines in the key module is pressed is detected as a first detection result. The second lines are driven to the first potential. Whether any key on each of the first lines is pressed is detected as a second detection result. One of the first lines is sequentially selected, and a press status of each key on the selected first line is scanned through the second lines so as to generate a coarse scan result. The press status of each key is obtained and whether the press status is misjudged is determined according to the first and the second detection results and the coarse scan result.