Touch Detecting Device Key Press Velocity Control
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Solution Overview
Problem
Electronic keyboard instruments fail to accurately detect key pressing operations and repetitions, particularly when keys are pressed beyond the third switch, leading to potential sound generation issues and compromised performance.
Innovation Solution
A touch detecting device with a control circuit that counts the time between the activation of first and second contact nodes, and outputs sound generation signals based on a threshold value, ensuring accurate detection of key presses and repetitions by considering the state of the third contact node.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a key is pressed to a position above the third switch at a constant velocity or higher, then a sound can be generated by hammer inertia in an acoustic piano, but electronic keyboard instruments fail to detect this key pressing operation accurately
Solution Approach 1:
The patent segments the key press detection into multiple stages by introducing intermediate detection points (first, second, and third determination points) along the key stroke path. Each determination point checks for key press state at specific positions, allowing the system to detect key presses that occur at different depths and velocities, including shallow presses above the third switch that mimic acoustic piano hammer inertia behavior.
Solution Approach 2:
The patent implements dynamic detection by continuously monitoring key press state at multiple determination points during the key stroke motion. The system adapts its detection criteria based on the key's position and velocity, enabling it to recognize valid key presses even when they don't reach the traditional third switch position, thus capturing the dynamic characteristics of acoustic piano hammer action.
2Device complexity
If only two switches are used for velocity detection, then the structure is simpler, but the ability to detect repetitions of key pressing with small stroke amplitude is reduced
Solution Approach 1:
The patent divides the key stroke path into multiple segments with determination points at different depths (first, second, third determination points). This segmentation allows the system to detect key presses at various stages of the stroke, including small amplitude repetitions that may not trigger traditional two-switch configurations, thereby improving repetition detection capability without requiring additional physical switches.
Solution Approach 2:
The patent adds a temporal dimension to the detection system by implementing multi-stage determination points that evaluate key press state at different positions and times during the stroke. This transforms the detection from a simple two-point measurement to a multi-dimensional assessment involving position, velocity, and timing, enabling accurate detection of rapid repetitions with small stroke amplitudes.
Data Source
AI summary
First and third counters count an ON time between first and second contact nodes of a key and an ON time between the second contact node and a third contact node, respectively. A second counter counts a time after counting of the first counter is completed. A counter memory stores velocity counter values representing count times of the first and third counters, and a correction time counter value representing the count time of the second counter. An arrival comparator circuit compares an arrival time value and the correction time counter value. In a case that the velocity count value of the first counter is larger than a threshold value, when the arrival comparator circuit detects that the arrival time value coincides with the correction time counter value, a controller outputs a sound generation instruction including touch information according to the velocity counter value loaded from the counter memory.