Abstract:
A hand-held power driven toothbrush carries a pair of exposed brush elements and self-contained driving means effective to directly drive one of said brush elements in oscillation, with linkage between the brush elements such that the second brush element is also oscillated, the two brush elements preferably being oscillated in opposite directions.

Description:
BRIEF SUMMARY OF THE INVENTION 
     The present invention relates to a motor driven toothbrush in which the brush elements are driven in rotary oscillation, and preferably in opposite directions respectively, by means of an exceptionally effective driving arrangement. 
     The need for a power driven toothbrush has been long recognized, and many suggestions have been made as to how such a device should be constructed. The requirements for such a device may be simply stated--it should be light and self-contained so as to be easily manually manipulated, the brush elements must be driven into prophylactically optimum brushing motion, the parts must be sturdy and reliable, and the part inserted into the user&#39;s mouth must be small and appropriately shaped--but to accomplish all of these objectives in a single structure is by no means simple, and hence the art is replete with suggested constructions. 
     Some of the requirements are mutually inconsistent--to make something small and light and at the same time sturdy and reliable is no mean task. In addition, obtaining optimum tooth cleaning and polishing from a motor driven brush element calls for considerable ingenuity, and prior art approaches to that objective have been less than satisfactory. Early approaches, such as those shown in Steinberg U.S. Pat. No. 2,601,567 of Jun. 24, 1952 and Lakin U.S. Pat. No. 2,598,275 of May 27, 1952 utilized single brush elements which were either rotated continuously in one direction or were swung back and forth, respectively. The desirability of utilizing more than a single driven brush element was soon realized, and devices of that nature are shown in Wolfson U.S. Pat. No. 4,048,690 of Sep. 20, 1977, Vrignaud U.S. Pat. No. 5,177,826 of Jan. 12, 1993, Hegemann U.S. Pat. No. 4,766,630 of Aug. 30, 1988, Rogers U.S. Pat. No. 4,320,774 of Mar. 23, 1982, and Ambasz U.S. Pat. No. 5,077,855 of Jan. 7, 1992. However, in none of these multiple brush elements devices are the brushes moved so as to have optimum brushing and polishing effect when hand-held for cleaning a person&#39;s teeth, nor are the driving connections to those brush elements simple, positive, and reliable while at the same time taking up very little space. 
     In addition, because tooth brushing is not the only prophylactic treatment for teeth, it is highly desirable that a power driven toothbrush be so constructed that, by ready replacement of one part with another, the device can be converted to another prophylactic operation on teeth, such as flossing between the teeth. The driving connection to the brush elements of a power driven toothbrush should, therefore, be such that the brushes can be readily removed from the handle portion of the device, with the handle then available to have some other part, such as a dental floss holder, attached thereto. 
     It is therefore a prime object of the present invention to devise a power driven toothbrush which can readily be held and manipulated by an individual and which will be effective to drive a pair of brush elements into optimum brushing movement, and to do so by means of structure which is simple, strong and reliable. 
     It is a further object of the present invention to provide such a device in which the power drive to the brush elements is such that the brush elements can be removed from a handle portion and some other device, preferably also power driven, can be attached, thus permitting the handle portion of the apparatus to do double duty. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     To the accomplishment of the above and to such other objects as may hereinafter appear, the present invention relates to the construction of a motor driven toothbrush as defined in the appended claims and as described in this specification, taken together with the accompanying drawings in which: 
     FIG. 1 is a front elevation exploded view of a preferred embodiment of the present invention with the brush-element-carrying part being separated from the handle portion of the apparatus; 
     FIG. 2 is a side elevational view of the toothbrush of FIG. 1 with the two parts assembled; 
     FIG. 3 is a cross-sectional view of a portion of the device of FIG. 2; 
     FIG. 4 is a cross-sectional view taken along the line 4--4 of FIG. 3; 
     FIG. 5 is a cross-sectional view taken along the line 5--5 of FIG. 3; and 
     FIG. 6 is a view similar to FIG. 1, but on a reduced scale, showing a flossing attachment in place instead of the brush attachment. 
    
    
     DETAILED DESCRIPTION 
     The preferred embodiment of the present invention as here specifically disclosed comprises two separate parts generally designated A and B, the part A comprising the handle part and containing the power drive and batteries and the part B, removably attached to the part A, carrying the brush elements 2 which ultimately perform the tooth brushing function. The part B may be mounted on and dismounted from the part A simply by sliding it into place, and, as shown in FIG. 6, the part B carrying the brush elements 2 can be substituted for by the part B&#39; shown in FIG. 6 adapted for holding dental floss for insertion between the user&#39;s teeth, an operation for which the brushes 2 are not prophylactically effective, and preferably imparting a back and forth movement to the floss to enhance its prophylactic effect. The details of this device as a flosser are shown and claimed in a copending application of Robert H. Meibauer entitled &#34;Power Driven Tooth Flooser&#34;, Ser. No. 08/126,386, Sep. 24, 1993. 
     The handle part A which may be grasped by the user comprises a casing 4 having a removable end cap 6, the lower end 8 of the casing 4 being adapted to receive batteries when the end cap 6 is removed and to make appropriate electrical connection between those batteries, a control switch 10 exposed on the upper portion of the casing 4 and a motor 12 mounted within the casing 4 and having an output shaft 14 carrying a pinion gear 16 which meshes with a second pinion 18 rotatably mounted within the casing 4 on a fixed axis and in turn meshing with an enlarged internally toothed gear 20 rotatably mounted in the casing 4 on fixed axis 22. The gear 20 carries, preferably integral therewith, an off-center ring 28 intersected by the axis 22. Rotatably mounted on the exterior of the ring 28 is a looped portion 29 of an arm 31 which extends out radially beyond the axis of the gear 20 and which carries a pin 33 which in turn is rotatably mounted in crank arm 35 which is fast on shaft 30, the shaft 30 being journaled in the forwardly extending portion 4a of the casing 4 and extending longitudinally outwardly therefrom at 32, there terminating in an exposed flattened portion 34, preferably semicircular in cross-section. In the preferred form here specifically disclosed, adapted to be used with the powered flosser attachment B&#39; of FIG. 6 as well as the brushing attachment B, the shaft 30 carries miter gear 36 which meshes with miter gear 38 fast on shaft 40 extending out through the casing 4 and carrying an exposed jam cleat 42 with tapered peripheral groove 44. 
     The switch 10 specifically here shown has two operating buttons 10a and 10b, depression of button 10a being effective to energize the motor 12 and depression of button 10b being effective to de-energize the motor 12. When the motor 12 is energized its output shaft 14 will rotate, thus rotating pinion gears 16 and 18 and internally threaded gear 20, this causing rotation of the ring 28 in an off-center fashion about the axis 22, that movement will be transferred to the arm 35 by the part 29, 31, causing that arm 35 to oscillate back and forth as indicated by the arrow 37 in FIG. 4, thus driving the shaft 30 in rotary oscillation and also imparting rotary oscillation to the exposed jam cleat 42. 
     The section B comprises a casing 48 having a lower cylindrical portion 50 slidably receivable over the portion 4a of the handle casing 4 with a friction fit, which fit can be enhanced by providing a projecting portion 4b on the casing portion 4a which frictionally engages the inner surface of the cylindrical portion 50 of the casing 48. As may best be seen from FIGS. 3 and 5, the casing 48 has a driven shaft 52 journaled therein, with the lower end of that shaft 52 having a preferably semicircular recess 54 into which the preferably semicircular end 34 of the drive shaft 30 is adapted to be received when the part B is placed on the part A, so that oscillatory rotation of the shaft 34 will be transmitted to the driven shaft 52. The inner end of the shaft 52 carries a miter gear portion 54 which meshes with a miter gear 56 rotatably mounted on bearing pin 58 which extends up from the bottom wall 60 of the casing 48 near its tip. An upwardly extending portion 62 of the miter gear 56 is made fast to a rotary brush carrier 64 journaled in an insert 65 in the upper wall 48a of the casing 48, which carrier 64 carries a set of bristles constituting one of the brush elements 2. Also mounted within the end portion of the casing 48, and rotatable on bearing pin 66, is a part 68 similar to the part 56, the part 68 extending up at 70 and made fast to the brush holder 72 also journaled in the casing wall 48a and carrying a set of bristles constituting the second brush element 2. The insert 65 is set into an appropriate aperture 67 in the upper casing wall 48a and is provided with a securing protrusion 69 received in an aperture 71 in the end wall 73 of the casing 48. A link 74, best seen in FIG. 5, is pivotally connected to crank arms 56a and 68a on parts 56 and 68 respectively and extends between them, its pivotal connection 76 to crank arm 56a being to one side of the axis of rotation of the part 56 and its pivotal connection 78 to crank arm 68a being to the other side of the axis of rotation of the part 68. 
     Hence when the part B is put in place on the part A and the motor 12 is energized the shaft 30 will be oscillated back and forth, the shaft 52 will be similarly oscillated, the gear 56 will then be oscillated about its axis of rotation and the part 68 will be oscillated about its axis of rotation, but with the gear 56 and part 68 oscillating in opposite directions. The two brush elements 2 will therefore also be oscillated back and forth in rotary motion and in opposite directions. This will provide for optimum tooth cleaning action as a result of the oscillatory movement of the brush elements 2, the close positioning of those brush elements with respect to one another, and also preferably the fact that they are rotated in opposite directions. The driving connection from the motor 12 to the brush elements 2 is positive, yet it takes up very little space and does not require the use of any heavy or complex mechanical elements, thus enabling the device to be simple, compact, and easily held and manipulated even by a child, while at the same time the device is sturdy and reliable and hence well suited to non-professional use. 
     When a flosser attachment B&#39; is mounted on the handle part A the ends of a length of floss carried thereby may be secured to the jam cleat 42 which is driven in rotary oscillation when the motor 12 is energized, thus causing the length of floss to move back and forth and produce an optimum flossing action when inserted between the teeth of the user. 
     While but a single embodiment of the present invention has been here specifically disclosed, it will be apparent that many variations may be made therein, all within the spirit of the invention as defined in the following claims.