Mechanically-driven, sonic toothbrush system

1. A toothbrush comprising

an electric motor including a drive shaft, wherein, when the electric motor is caused to operate, the drive shaft continuously rotates until the motor is caused to stop;

a brush shaft; and

a drive assembly consisting of a bar linkage coupled between the drive shaft and the brush shaft, the bar linkage comprising

a coupler having a first end operably coupled to the brush shaft and a second end;

an eccentric pin rotationally received within the second end of the coupler, the eccentric pin having a rearward end shaft axially aligned with an axis of the drive shaft and a mid-portion axially offset from the axis of the drive shaft, wherein

the rotation of the drive shaft causes the eccentric pin to rotate within the second end; and

the rotation of the eccentric pin causes the coupler to oscillate to convert the rotation of the drive shaft into oscillation of a toothbrush head supported on an end of the brush shaft.

2. The toothbrush of claim 1 , wherein the bar linkage-further comprises a crank arm interconnected between the drive shaft and the coupler.

3. The toothbrush of claim 2 , wherein the crank arm is fixedly connected to the drive shaft on a first side and fixedly connected to the rearward end shaft of the eccentric pin on a second side opposite the first side.

4. The toothbrush of claim 2 , wherein the crank arm further comprises an additional weight component to alter a center of mass of the bar linkage and impart a balance or an imbalance to the bar linkage.

5. The toothbrush of claim 1 , wherein the bar linkage further comprises a rocker arm pivotably interconnected between the coupler and the brush shaft.

6. The toothbrush of claim 5 , wherein the rocker arm pivotably connects to the coupler at a first axis of rotation and the brush shaft pivotably connects to the coupler at a second axis of rotation.

7. The toothbrush of claim 5 , wherein the rocker arm further comprises an additional weight component to alter a center of mass of the bar linkage and impart a balance or an imbalance to the bar linkage.

8. The toothbrush of claim 1 , wherein the bar linkage further comprises

a crank arm interconnected between the drive shaft and the coupler;

a rocker arm interconnected between the coupler and the brush shaft; and

one or more additional weight components attached to either the crank arm or the rocker arm, or both, to alter a center of mass of the drive assembly and impart a balance or imbalance to the drive assembly.

9. The toothbrush of claim 1 further comprising

a handle portion housing the electric motor; and

a power source housed within the handle portion and electrically connected with the electric motor.

10. The toothbrush of claim 1 further comprising a bracket to which the electric motor is attached and to which the brush shaft is rotationally mounted.

11. The toothbrush of claim 1 , wherein the electric motor continuously rotates at a speed of between 12,000 rpm and 18,000 rpm.

12. A toothbrush providing oscillating bristle motion comprising

a continuously rotating drive system including a output shaft;

a brush shaft; and

a bar linkage between the drive system and the brush shaft, the bar linkage comprising

a coupler having a first end operably coupled to the brush shaft and a second end;

an eccentric pin rotationally received within the second end of the coupler, the eccentric pin having a rearward shaft axially aligned with the output shaft of the drive system and a mid-portion axially offset from output shaft of the drive system, wherein

the rotation of the output shaft causes the eccentric pin to rotate within the second end; and

the rotation of the eccentric pin causes the coupler to provide oscillating, sonic speed output motion to the brush shaft.

13. The toothbrush of claim 12 , wherein the linkage further comprises one or more removable mass components that may be removed and replaced with other removable mass components of differing mass to alter a center of mass of the linkage and impart a balance or an imbalance to the linkage.

14. The toothbrush of claim 12 , wherein the output shaft of the drive system is axially offset from an axis of the brush shaft.

15. The toothbrush of claim 12 , wherein the bar linkage further comprises a cam that causes a portion of the bar linkage to revolve about the output shaft of the drive system.

16. The toothbrush of claim 12 , wherein the oscillating motion of the brush shaft is between 200 and 300 cycles per second.

17. A method of designing a toothbrush having a continuously rotating drive system, a brush shaft, and a linkage between the drive system and the brush shaft, the method comprising

performing a finite element analysis on the linkage; and

determining a weight distribution in the linkage based upon the finite element analysis to position a center of mass of the linkage and impart a balance or a selected imbalance to the linkage.

18. The method of claim 17 further comprising adjusting one or more replaceable weights within the linkage to alter the center of mass or alter the selected imbalance.