Abstract:
Toothbrushes that utilize a rotating eccentric weight positioned in or near the head of the toothbrush to cause movement of the head, and methods relating to same.

Description:
[0001]    This application claims the benefit of U.S. provisional application No. 60/340,557 filed on Oct. 30, 2001 and titled “Disposable Electric Toothbrush” incorporated herein by reference in its entirety. 
     
    
     
         [0002]    FIELD OF THE INVENTION  
           [0003]    The field of the invention is electric toothbrushes.  
         BACKGROUND OF THE INVENTION  
         [0004]    The benefits of electric toothbrushes are well known. One type of electric toothbrush utilizes an eccentrically moveable weight (by coupling an eccentric weight to a rotating motor) shaft to cause a handle of the toothbrush to vibrate, the vibration of the handle being transmitted to the bristles of the brush via a neck coupling the bristle portion/head of the brush to the handle. The use of such devices is not always desirable however, at least in part because of the relatively large amount of vibration required in the handle in order to get an acceptable amount of vibration of the bristles, and the corresponding cost in energy and high degree of vibration transferred to the hand of someone using such a brush. Example of such prior art toothbrushes can be found in U.S. Pat. Nos. 3,685,080, 5,421,726, 5,651,157, 5,706,542, 5,718,667, and 5,706,542. An eccentric weight, as the term is used herein, is a moveable weight that does not rotate about an axis that passing through the center of mass of the weight. Such a weight may or may not be symmetrical about an axis, but, if mounted to a rotating shaft, is not symmetrical (at least in regard to mass distribution) about the shaft.  
           [0005]    Unfortunately, current toothbrushes are constructed in a manner that raises the cost of such toothbrushes beyond the reach of many people. Moreover, such toothbrushes are unduly cumbersome because of their weight, and size, and/or because of the battery charger that is used to recharge them. Thus, there is-a continuing need for affordable electric toothbrushes that are not unduly cumbersome.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention is directed to toothbrushes that utilize a rotating eccentric weight positioned in or near the head of the toothbrush to cause movement of the head relative to a handle of the toothbrush, and methods relating to same. Positioning the weight in or near the head allows production of toothbrushes having numerous advantages over convention toothbrushes and powered toothbrushes including but not necessarily limited to: (a) use of a relatively low power motor to rotate the weight; (b) lighter weight; (c) reduced handled vibration; (d) longer battery life; (e) higher reliability; and/or (f) disposability. The phrase “near the head” is used herein to indicate that the weight is at least closer to the head than to the body/handle, preferably separated from the head by a distance less than half the distance separating it from the body.  
           [0007]    Disposable embodiments are possible as the use of a low power motor permits the toothbrush to go for long periods without recharging its batteries. Obtaining long periods of use without recharging permits a single battery or set of batteries to last as long as the bristles of the brush. The use of a lower power motor, a simple movement mechanism, non-rechargeable batteries, and non-replaceable bristles permits the total cost of the brush to be brought to a level where it is reasonable to dispose of the toothbrush after the bristles and/or batteries wear out. Making the toothbrush disposable permits the batteries to be permanently sealed inside the toothbrush which in turn increases safety while reducing manufacturing costs.  
           [0008]    Various objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention, along with the accompanying drawings in which like numerals represent like components. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a view of a first toothbrush embodying the invention.  
         [0010]    [0010]FIG. 2 is a detail view of the motion of a weight positioned within the head of the toothbrush of FIG. 1.  
         [0011]    [0011]FIG. 3A is a detail view of the motion of the head of the toothbrush of FIG. 1 for embodiments where the motion is circular/orbital.  
         [0012]    [0012]FIG. 3B is a detail view of the motion of the head of the toothbrush of FIG. 1 for embodiments where the motion is vertical.  
         [0013]    [0013]FIG. 3C is a detail view of the motion of the head of the toothbrush of FIG. 1 for embodiments where the motion is horizontal.  
         [0014]    [0014]FIG. 4 is a view of a second toothbrush embodying the invention. 
     
    
     DETAILED DESCRIPTION  
       [0015]    Referring first to FIG. 1, toothbrush  1000  comprises body  1100 , bristles  1200 , motion assembly  1300 , power source(s)  1400 , and control assembly  1500 .  
         [0016]    Body  1100  comprises head  1110 , neck  1120 , and handle  1130 . Head  1110  is the portion of body  1100  to which bristles  1200  are mounted. Neck  1120  is the portion of body  1100  that couples head  1110  to handle  1130 . Handle  1130  is the portion of body  1100  that is adapted to be gripped by someone using toothbrush  1000 . Body  1100  also comprises body cavity  1101  that is subdivided into cavities corresponding to head  1110 , neck  1120 , and handle  1130 . The sub-cavities of body cavity  1101  are head cavity  1111 , neck cavity  1121 , and handle cavity  1131 . Motion assembly  1300  comprises motor  1310 , motor spindle  1311 , coupler  1312 , flexible wire shaft  1320 , shaft bearing  1321 , weight  1330 , and weight well  1331 . Power source  1400  comprises two AAA batteries. Control assembly  1500  comprises the switches and circuitry used to control the movement of weight  1330  by controlling the use of motor  1310 .  
         [0017]    Distance D 1  is the distance from the tip toothbrush  1000  to the center of mass of weight  1330 . Distance D 2  is the distance from the center of mass of weight  1330  to motor  1310 . Distance D 3  is the total length of the head  1110  and neck  1120  portions of body  1100 . Distance D 4  is the length of handle  1130 .  
         [0018]    Body  1100  is preferably formed a plurality of molded plastic pieces, the pieces coupled together in a manner which hermetically seals the body cavity  1101  from the exterior of toothbrush  1000 . Sealing the various components of motion assembly  1300  and power assembly  1400  within body cavity  1101  is contemplated to increase the life of motion assembly  1300  and power assembly  1400  by preventing dirt, water, or other substances from affecting motion assembly  1300  and power assembly  1400 . Sealing the various components within body cavity  1101  is also contemplated as decreasing the risk of any chemicals or parts from the components adversely affecting a user of toothbrush  1000 .  
         [0019]    Head  1110  and handle  1130  may have any size and shape suitable as a toothbrush head and handle so long as they are large enough to enclose their respective cavities. The handle cavity  1131  is preferable sized and dimensioned to securely hold power source  1400 . Head cavity  1111  is preferably sized and shaped to position and permit proper operation of the weight and shaft, and to position the weight well and shaft bearing of motion assembly  1300 .  
         [0020]    Neck  1120  is preferably sized and dimensioned to provide a desired overall length and flexibility to toothbrush  1000  and to contain neck cavity  1121 . Neck cavity  1121  is preferably sized and dimensioned to allow flexible wire shaft  1320  to extend from the motor  1310  to the shaft bearing  1321  without having flexible wire shaft  1320  contact any of the sidewalls of neck cavity  1121 . It is contemplated that the structure of neck  1120  may vary between embodiments, with the variance in structure resulting in different motions for head  1110  as weight  1330  rotates.  
         [0021]    Looking at FIGS.  3 A- 3 C, it is contemplated that proper structuring of neck  1120  may result in a circular/orbital motion of head  1110 , a vertical motion, and/or a horizontal motion. In FIG. 3A, the motion M 1  of head  1110  is circular/orbital in that head  1110  moves follows a path that is at least somewhat similar to the circle shown having a radius M 1 R, and movement distance M 1 V is approximately equal to its horizontal movement distance M 1 H. In FIG. 3B, the motion M 2  of head  1110  is vertical in that vertical movement distance M 2 V is substantially larger than the horizontal movement distance M 2 H. In FIG. 3C, the motion M 3  of head  1110  is horizontal in that horizontal movement distance M 3 H is substantially larger than the vertical movement distance M 3 V.  
         [0022]    Bristles  1200  are preferably permanently mounted to head  1110 . It is contemplated, however, that bristles  1200  may be removeably mounted to head  1110  for ease of replacement. Similarly, head  1110  and neck  1120  may be removeably coupled to each other and/or neck  1120  may be removeably coupled to body  1130 . Motion assembly  1300  is used to convert energy from power source(s)  1400  to movement of head  1110 . In the preferred embodiment, the motor spindle  1311  is coupled to flexible wire shaft  1320  by a polyimide or other polymer tube couple  1312  such that when power is applied to motor  1310 , spindle  1311  and flexible wire shaft  1320  rotate. Weight  1330  is mounted to flexible wire shaft  1320  such that flexible wire shaft  1320  does not pass through the center of weight  1330 . FIG. 2 illustrates the motion of weight  1330  as flexible wire shaft  1320  rotates to cause the head to move as illustrated in FIGS.  3 A- 3 C. Weight well  1331  permits weight  1330  to rotate without contacting any of the side walls of head cavity  1111  or body cavity  1101 . The movement caused by rotation of weight  1330  is transferred to head  1110  via shaft bearing  1321 . Shaft bearing  1321  is preferably chosen to minimize the noise generated by movement of flexible wire shaft  1320  and weight  1330 . Although fixed in regard to shaft  1320 , weight  1330  is rotatably mounted within toothbrush  1000  as it is mounted in a manner that permits it to rotate within the toothbrush.  
         [0023]    It is contemplated that, for improved motion of head  1110 , distance D 1  should be less than distance D 2 . It is also contemplated that having distance D 2  be at least 50 mm or 2inches inches may prove advantageous. Similarly, distance D 1  may be less than 12.5mm or 0.5inches. It is also contemplated that it may be advantageous for the ratio of D 2  to D 1  to be at least 4:1or 500 %. It is also contemplated that it may be advantageous to minimize the distance between weight  1330  and shaft bearing  1321  in order to maximize the transfer of motion of weight  1330  to head  1110 . In some instances, shaft bearing  1321  may be positioned between weight  1330  and motor  1310 .  
         [0024]    It is also contemplated that making shaft  1320  and coupling  1312  flexible facilitates in transferring and concentrating energy in the head of the brush by (in conjunction with neck  1120 ) isolating the orbital energy of the brush head from the mass of the handle, drive, and batteries. In some embodiments, the amount of flexibility of in shaft  1320  and coupling  1312  may vary, although it is preferred that as shaft  1320  is made stiffer, coupling  1312  is made more flexible. Similarly, it is preferred that as coupling  1312  is made stiffer, shaft  1320  is made more flexible.  
         [0025]    Power source  1400  is preferred to comprise two AAA batteries. However, alternative embodiments may use different types of batteries or capacitors as power source  1400 . It is preferred that the choice of power source be made such that the amount of time that power source  1400  is able to adequately power motor  1310  is at least 8 hours, and more preferably at least 9-12 hours. If usage is about 2 minutes a day, the life of the brush would be approximately 8 months for an 8 hour battery life, and 9 -12 month for a 9-12 hour life.  
         [0026]    Control assembly  1500  may comprise a simple switch used to complete or break an electrical connection between power source  1400  and motor  1310 . However, alternative embodiments may use more complex means of motor control.  
         [0027]    [0027]FIG. 4 illustrate one alternate embodiment having an angled neck. As shown in FIG. 4, toothbrush  2000  comprises body  2100 , bristles  2200 , motion assembly  2300 , power source(s)  2400 , and control assembly  2500 . Body  2100  comprises head  2110 , neck  2120 , and handle  2130 . Head  2110  is the portion of body  2100  to which bristles  2200  are mounted. Neck  2120  is the portion of body  2100  that couples head  2110  to handle  2130 . Handle  2130  is the portion of body  2100  that is adapted to be gripped by someone using toothbrush  2000 . Body  2100  also comprises body cavity  2101  that is subdivided into cavities corresponding to head  2110 , neck  2120 , and handle  2130 . The only sub-cavity of body cavity  2101  shown is handle cavity  2131 . Motion assembly  2300  comprises motor  2310  and motor spindle  2311 , as well as a coupler, flexible wire shaft, shaft bearing, weight, and weight well which are similar to those shown in FIG. 1. Power source  2400  comprises two AAA batteries. Control assembly  2500  comprises the switches and circuitry used to control the use of motor  2310 .  
         [0028]    The use of either toothbrush  1000  or  2000  can be described as using an electric toothbrush comprising causing an eccentric weight located within a head of the toothbrush to rotate and, while the weight is rotating, using the toothbrush to brush teeth. More specifically, causing an eccentric weight to rotate comprises electrically connecting an electric motor to a power source so as to cause a motor spindle to rotate, the motor spindle causing a shaft to rotate, the shaft causing the eccentric weight to rotate.  
         [0029]    Thus, specific embodiments and applications of disposable electronic toothbrushes have been disclosed. It should be apparent, however, to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. In particular, it is contemplated that any form of toothbrush utilizing a rotating eccentric weight located in or near the bristle portion of the toothbrush may be used so long as the choice of structure and materials does not prevent rotation of the weight from generating acceptable movement of the bristles. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.