Electrical Toothbrush Asymmetric Threshold Control for Vibration Noise

The patent applies parameter changes by using different threshold values for different switching directions. Specifically, a first threshold value is used when switching from a lower operation mode to a higher mode, while a second threshold value (different from the first) is used when switching from a higher mode to a lower mode. This asymmetric threshold parameter change prevents frequent switching caused by vibration noise while maintaining simple control logic.

The patent resolves this contradiction by changing the threshold parameters asymmetrically. When the brush angle approaches the boundary (e.g., 35 or 55 degrees), the different threshold values prevent oscillation between modes. The first threshold value creates a hysteresis effect that maintains mode stability at boundaries while still allowing transitions when the brush angle is clearly within the desired range for periodontal pocket brushing.

The patent applies parameter changes by establishing asymmetric threshold values where the first threshold value differs from the second threshold value. This creates a hysteresis band that filters out vibration noise while maintaining sensitivity to genuine brush angle changes. The asymmetric thresholds ensure that small vibrations near the boundary cannot cause false switching, while still responding appropriately to deliberate changes in brushing position.