Electric toothbrush

Information

  • Patent Grant
  • 6453498
  • Patent Number
    6,453,498
  • Date Filed
    Wednesday, July 26, 2000
    23 years ago
  • Date Issued
    Tuesday, September 24, 2002
    21 years ago
Abstract
An electric toothbrush has a housing incorporating a motor with a drive shaft rotatable about a longitudinal axis A. A shank extends beyond the housing and is integrally formed with a brush head at its remote end. The shank is pivotably supported intermediate its length in an end wall of the housing. An eccentric cam mounted to the shaft cooperates with a cup on a near end of the shank to form a mechanical coupling. When the shaft rotates both the near end and the brush head moves through a circular path.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The invention relates to electric toothbrushes.




2. Description of Prior Art




Electric toothbrushes are well-known and generally comprise a handle incorporating a motor and a shank that fits to the housing and has a brush head at its remote end. The motor is arranged to move bristles held in the brush head to cause the bristles to rotate or vibrate in some cases by vibrating the shank relative to the housing. In this way a more efficient brushing and cleaning action is achieved than simply manually moving the bristles over the surfaces of teeth and gums.




Electrical toothbrushes also have switches to turn the motor ON and OFF and in some case to enable different motor speeds to be selected. Normally, the present day toothbrushes have compartments for a battery, which may be a re-chargeable battery. The brush head may detachable from the shank, for cleaning or replacement. These are all features well-known in the art and so will not be further described in the specification. The present invention is more particularly concerned with the manner of driving a brush head, which so far is often complex, and/or comparatively expensive to make, and/or prone to failure.




SUMMARY OF THE INVENTION




It is an object of the invention to overcome or at least reduce these problems.




According to the invention there is provided an electric toothbrush comprising a housing incorporating an electric motor having a drive shaft that rotates about a longitudinal axis of the housing, a shank extending beyond one end of the housing generally in line with the longitudinal axis that supports a brush head at its remote end, in which the shank is pivotably supported intermediate its length adjacent the one end of the housing, and including a mechanical coupling between the drive shaft and a near end of the shank arranged to cause both the near end and the brush head to move through a circular path as the drive shaft rotates.




The mechanical coupling may comprise an eccentric cam mounted to one of the drive shaft and the near end of the shank and a cup that fits over and engages sides of the cam on the other of the drive shaft and the near end of the shank.




The eccentric cam may have a peripheral continuous channel that extends axially with respect to the longitudinal axis and the cup has a finger that engages in the channel so that when the drive shaft rotates the cup (and the shank) is urged backwards and forwards along the longitudinal axis.




The shank may be held to pivot by the sides of an aperture formed in a wall of one end of the housing.




A resilient sealing member may be included that fits around the shank and to the said wall.




The general “toothbrush arrangement” may also be used for skin care products such as brushes or rubbing pads.











BRIEF DESCRIPTION OF THE DRAWINGS




Electric toothbrushes according to the invention will now be described by way of example with reference to the accompanying Schematic drawings in which:





FIG. 1

is a sectional bottom view of one toothbrush;





FIG. 2

is a sectional side view of the toothbrush;





FIG. 3

is a sectional bottom view of another toothbrush;





FIG. 4

is a sectional bottom view of the other toothbrush in a different configuration; and





FIG. 5

is a sectional side view of the other toothbrush.











DESCRIPTION OF THE PREFERRED EMBODIMENT




Referring to the drawings, in

FIGS. 1 and 2

the toothbrush comprises a housing


10


incorporating an electric motor


11


having a drive shaft


12


rotatable about a longitudinal axis A. A shank


13


extends generally in line with the longitudinal axis beyond one end


14


of the housing


10


. The shank


13


is integrally formed with a brush head


15


to which a number of bristle tufts


16


are mounted. A single tuft may be supported in the brush head and used for cleaning teeth and gums. Single tufts are known and often referred to an “inter dental cleaners”.) The shaft


13


is pivotally supported intermediate its length by an aperture formed in the end


14


of the housing. A circular washer


17


mounted in the aperture fits into a peripheral groove


18


formed in the shank


13


.




The drive shaft


12


and a near end of the shank


13


are mechanically coupled so that when the motor


11


is running both the near end and the brush head describes a circle. This is achieved by an eccentric cam


19


mounted to the drive shaft


12


that couples with a cup


20


on the near end of the shank. The cup


20


slidingly fits over the cam


19


and bears against the cam surface in use.




A resilient sealing member


21


fits snugly into a groove


22


formed in the shank


13


and to the end


14


of the housing.




It will be appreciated that the mechanical coupling may comprise an “eccentric” cup


19


on the drive shaft


12


and a cam that runs inside the cup fitted on the near end of the shank


13


. Such a coupling will also cause the brush head to describe a circle when the shaft


12


is rotated.




In

FIGS. 3

,


4


and


5


a similar electric toothbrush is shown except a different mechanical coupling between the drive shaft and the near end of the shank is provided. An eccentric cam


23


is formed with a continuous slot


24


. The slot


24


extends in an axial direction with respect to the longitudinal axis A. Thus, when the drive shaft


12


rotates the brush head


15


describes a circle as in

FIGS. 1 and 2

, and also moves backwards and forwards along the longitudinal axis. Thus, the brush head


15


is moved through a three-dimensional elliptical path as the drive shaft


12


rotates.




The

FIGS. 3

,


4


and


5


show three different configurations each represents the head in respective positions along the elliptical path. In order to allow the shank to pivot and to slide as required, a short neck or groove


25


is formed that fits snugly into and is supported by the circular washer


17


.




It will be noted in

FIGS. 1 and 2

a section


26


of the shank is shown in cross-hatching. The shank


13


is normally formed of relatively rigid plastics material and the section


26


is made of relatively flexible material. This allows the shaft adjacent the cup


20


to flex more and such that, if the brush head


15


is held stationary when the motor


11


is turned ON, the motor can start to drive the cam


19


as required. If the shank cannot flex sufficiently for this condition, the motor may stall when initially switched ON.




It will be appreciated that the required or preferred differential flexibility may be provided in other manners such as by narrowing the diameter of a section of the shank. It will also be appreciated that the “flexible” section


26


may be placed in the shank at other positions along its length, that is, on either side of its pivotable support.




Hand-held skin care appliances may also be provided using the “toothbrush arrangement” described herein. In such appliances the described bristles are replaced with softer bristles or a pad that can be pressed against the skin and vibrated/oscillated to clean and stimulate the surface of the skin as required.



Claims
  • 1. An electric toothbrush comprising:a housing incorporating an electric motor having a drive shaft that rotates about a longitudinal axis of the housing; a shank extending beyond one end of the housing generally in line with the longitudinal axis that supports a brush head at its remote end, the shank being pivotably supported intermediate its length adjacent the one end of the housing; and a mechanical coupling between the drive shaft and a near end of the shank arranged to cause both the near end and the brush head to move through a circular path as the drive shaft rotates, the mechanical coupling further comprising an eccentric cam mounted to the drive shaft and a cup that fits over and engages sides of the cam on the drive shaft, the cup mounted on the near end of the shank, the eccentric cam having a peripheral continuous channel that extends axially with respect to the longitudinal axis and the cup has a finger that engages in the channel so that when the drive shaft rotates the cup is urged backwards and forwards along the longitudinal axis.
  • 2. An electric toothbrush according to claim 1, in which the shank is held to pivot by sides of an aperture formed in a wall of said one end of the housing.
  • 3. An electric toothbrush according to claim 2, including a resilient sealing member that fits around the shank and to the said wall.
  • 4. An electric toothbrush according to claim 1, in which a relatively flexible section of the shank is provided in the shank at one side of its pivotable axis.
Priority Claims (1)
Number Date Country Kind
9918081 Jul 1999 GB
US Referenced Citations (12)
Number Name Date Kind
2372731 Nalbach et al. Apr 1945 A
2379049 Tompkins Jun 1945 A
2648787 Smithson, Jr. Aug 1953 A
3159859 Rasmussen Dec 1964 A
3168834 Smithson Feb 1965 A
3270360 Kropp Sep 1966 A
3379906 Spohr Apr 1968 A
3535726 Sawyer Oct 1970 A
3546501 Kircher Dec 1970 A
3699952 Waters et al. Oct 1972 A
4175299 Teague, Jr. et al. Nov 1979 A
5448792 Wiedemann et al. Sep 1995 A
Foreign Referenced Citations (2)
Number Date Country
1488628 Oct 1977 GB
1580130 Nov 1980 GB