Abstract:
A visually appealing toothbrush having an applicator portion including a head and a track and including a replaceable bristle bed, wherein the track on which a bristle bed is slidingly mounted is rotatable out of a longitudinal axis of the handle into an open position by the rotation of a knob at the end of the handle, the open position allowing disengagement and replacement of the bristle bed, the track then being rotatable back into the longitudinal axis of the handle in order to trap and lock a newly mounted bristle bed by means of a stop at an extremity of the head.

Description:
FIELD OF THE INVENTION 
     The field of this invention is personal hygiene. More particularly, the field of this invention is toothbrushes, and especially those with disposable or replaceable parts. 
     BACKGROUND OF THE INVENTION AND DISCUSSION OF THE PRIOR ART 
     The humble tooth brush has long been a target of inventive art. In particular, it has long been recognized that the bristle or brush section generally wears down faster than the handle, rendering the brush unusable, and generally requiring the brush&#39;s complete disposal and replacement. Numerous methods have thereby been proposed which allow the toothbrush head or bristle portion to be replaced while reusing the handle. 
     Today, however, an examination of the products available in any drugstore will reveal that with the exception of expensive motorized toothbrushes, the disposable head concept has not been a commercial success. The reason for this lack of success is not hard to divine: the minor expense of a new molded plastic or rubber handle with integral bristles removes the economic incentive to provide a more expensive reusable handle. Despite the apparent waste of material, economics still favors disposal of the simple, single-piece toothbrush. 
     Also, a toothbrush handle having been in service long enough to wear down the bristles, though itself not actually substantially worn, may appear to be in used condition through hard water or dried toothpaste deposits. These deposits form even with regular rinsing, and so create an additional incentive to throw away the entire inexpensive brush assembly away rather than clean the handle. The user enjoys the “inconspicuous consumption” of a new toothbrush. 
     There may be a reason other than economics to provide a method of replacing of the brush head, and at more frequent intervals than required by the wear of the bristles: hygiene. Studies have shown that a toothbrush in daily use harbors both minute food particles and bacteria. For this reason a user may want to replace the bristles more frequently than dictated by wear. A consumer may also occasionally want to allow a person whom he does not wish to risk cross-contamination with to borrow his toothbrush. 
     Consumers who wish to replace the bristles at high frequency may find the expense of using a fresh single piece toothbrush each time to be unacceptable. Therefore, while simple economics may not support the concept of reusing a handle when the bristles have been worn and require replacement, there may be demand for such a product for more frequent bristle exchanges, analogous to the provision of a fresh dinner napkin with each diner and each meal. There is no product on the market which permits convenient and economical replacement of the bristles of a toothbrush at frequent intervals. 
     For purposes of hygienic bristle exchange, all disposable head toothbrushes known to the inventor have one or more disadvantages. Existing art either requires the user to handle the bristle mounting structure directly, thus providing a ready source of cross-contamination and tending to defeat the purpose of hygienic interchange, or require considerable dexterity in manipulating springs and clips and other small parts to change heads, or lack a secure way of securing the disposable head to the handle, risking unintended disengagement while brushing, or share some combination of these drawbacks which would be advantageous to overcome. One early model for example slides a brush head onto a grooved sheet metal track, only secured by friction, which track might severely injure the gums of a user should the brush head come off during vigorous brushing. 
     It therefore would be advantageous to provide a toothbrush with replaceable bristles and supporting structure, which was simple and economical enough for frequent replacement, which minimized handling requirements for the replaceable parts, which provided a secure lock or engagement of a replaceable part to prevent unintended disengagement and overcame the other limitations of the prior art. 
     It would also be advantageous to provide a product having these features which was easy and enjoyable for a user to operate, and thereby encouraged frequent bristle replacement, both maximizing the hygienic advantages to be obtained from using the product, and increasing the economic advantages to the manufacturer of the device. 
     SUMMARY OF THE PRESENT INVENTION 
     A dental care instrument or toothbrush has at least two elements in a handle or grip that rotate relative to one another. The rotating elements are provided with knurled or other frictional gripping surfaces to facilitate gripping by a user and to enable the user to impart opposing rotational motion to the segments. The relatively rotating elements may be portion of the handle which the user grasps in the process of brushing the teeth and a knob mounted on an end of the handle away from the brush head, for the purpose of operating the mechanism to replace the brush head. 
     The handle is hollow, and contains an internal mechanical linkage. Application of opposing rotational motion to the rotating elements causes, via the internal mechanical linkage, a rotation of a U-shaped frame or track located on the opposite or head end of the instrument out of a longitudinal axis of the head, thereby allowing replacement of bristles mounted on a grooved bristle bed which slides onto and off the U-shaped track. 
     In this patent application, the term “brush head” is used synonymously with the term “bristle bed” and should not be confused with the head of the toothbrush, which is a section of the toothbrush in an applicator section of the toothbrush. The applicator section of the toothbrush comprises a head and a neck whereby the head is connected to the toothbrush handle. The track is adapted to engage a disposable bristle bed, such as by the track engaging a portion of the bed having grooves. When the U-shaped track is rotated out of the longitudinal axis of the head a disposable bristle bed may be readily engaged or disengaged from the track by sliding. When the track is rotated back into the axis of the head, the track and bed lock in a closed position at the end of rotational travel when the track or bristle bed engage a lip or stop located on a tip of the head, in order to prevent the bristle bed from becoming disengaged. 
     The arrangement of the invention prevents unintended disengagement of the bristle bed by employing a locking surface to prevent travel of the bed in a closed position of the track and not relying entirely on friction to secure the bed, unlike U.S. Pat. No. 1,092,014 to Briggs which shows no evidence of contemplating other than a simple frictional fit. Rotation of the track in Briggs is solely a means of allowing the user to select a variable angle of brush head for the user&#39;s brushing preference. The rotation of the track has nothing to do with removal of the bristles, which may be removed and replaced with the track at any angle. In the present invention rotation of the track is provided not to alter the geometry of the brush for brushing, but entirely in the service of removal and replacement of the bristles, which are locked in by the lip or stop when the track is in a first, closed, position and removable only when the track is in a second, open position. 
     In the unlikely event that the tracks moves off the closed position during use, the user will notice the bristle bed shifting and return the brush head to its use or service position. It is extremely unlikely that sufficient unintentional rotation of the track could occur to allow the bristle bed to become inadvertently disengaged from the track. This is partially due to internal gearing, to be described below, which prevents rotation of the track by pushing the track directly. Instead, one has to turn the knob. The combination of this gearing and a fiction fit of the bed or track with the lip is sufficient to prevent unintended movement of the brush head. However, snap fit or other locking devices may be added for additional security. 
     A bend or elbow is advantageously added to the toothbrush between the handle and the head, in a region called the neck, to allow a more natural brushing angle with respect to a user&#39;s mouth, but this is geometry optional to the invention. 
     In a process of use, starting with an empty track fully rotated out the axis of the head to an open position, a user may open a sanitary package containing an individual brush head, for example, by ripping off an end closure of that package, and the replacement head may thereby be handled by the package or bag without the user contacting the bristles, while it is slid onto the track. The user then appropriately rotates the handle sections to cause the track to rotate back into the axis of the handle and engage in a use position, wherein the brush head is blocked from sliding movement by a stop on the end of the handle. The dental care instrument is now ready for brushing. 
     When a user later wishes to dispose of the used brush head, he reverses the operation by twisting the rotating section of the handle in the opposite direction, rotating the track out of the axis of the handle, and allowing removal of the brush head. It is not necessary for the user to grasp the brush head to remove it, however, since it may be simply flipped off into the garbage. Thereby it is possible for the user concerned about hygiene to both load and unload the unit without contaminating either himself or the bristles; a feature which also may be of use in institutional or medical settings. 
     Alternatively, replacement heads may be packaged with multiple units in a single closure, analogous to double edge razor blades, and in a manner adapted to allow removal of one unit by insertion of the prongs of the U-shaped track into the package to engage a single bristle head, which is then removed from the package using the toothbrush as a handle, and then locked into place as described above, as will be apparent to those skilled in the art. 
     IMPORTANT OBJECTS AND ADVANTAGES 
     The following important objects and advantages of the present invention are: 
     (1) To provide a toothbrush with a replaceable bristle bed; 
     (2) To provide a toothbrush with a replaceable bristle bed which operates in an economical way; 
     (3) To provide a toothbrush with a disposable bristle bed which minimizes the need to handle the old and new bristles on the part of a user effecting a replacement; 
     (4) To provide a method for replacing a toothbrush bristle bed which is simple for a user to operate; 
     (5) To provide a method for replacing a toothbrush bristle bed which a user can operate in an hygienic way, without contacting the new or used bristles; 
     (6) To provide a toothbrush with a disposable bed that carries bristles which bed slidably engages a track during use; and 
     (7) To provide a disposable bristle bed toothbrush and method of using the same which is enjoyable for a user, and encourages frequent bristle replacement. 
     These and other objects of the invention will become apparent from reading the attached specification. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the toothbrush of the present invention. 
     FIG. 1 a  is a cross-sectional view of a disposable bristle bed, showing the recessed grooves therein which engage the track in the handle. 
     FIG. 2 is a rear elevation view of the toothbrush of the present invention, in a partial broken-away view showing internal mechanism, and with the bed and bristles removed. 
     FIG. 3 is a side elevation view of a toothbrush of the present invention, also partially broken away, and with the bed and bristles removed for clarity. 
     FIG. 4 a  is a side elevation view of the present invention showing a bristle bed mounted on the toothbrush handle. 
     FIG. 4 b  is a front elevation view of the present invention showing the track rotated out of the longitudinal axis of the handle. 
     FIG. 4 c  is a front elevation view of the present invention showing the step of removing a used bristle bed from the handle of the present invention. 
     FIG. 4 d  is a front elevation view of the present invention showing the step of inserting a new bristle bed onto the track. 
     FIG. 4 e  is a front elevation view of the present invention showing the track rotated back into an axis of the handle with the new bristle bed thereby in a position ready for use. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The apparatus of the present invention will now be illustrated by reference to the accompanying drawings. The toothbrush of the present invention has been assigned reference numeral  10  Other elements have been assigned the reference numerals referred to below. 
     Toothbrush  10  as generally shown in FIG. 1 comprises a hollow handle  12  with gripping portions  14 ,  16 , an applicator section  18  including a head  20  and a neck  22 , the head including a track  24  which is pivotally mounted to a lower portion of the head. The toothbrush also includes bristles  26  sitting on a bed  28  (shown in cross section in FIG. 1 a ) which is slidably engageable to track  24 , and a shaft  30  (FIGS. 2 and 3) running through hollow handle  12  and neck  22  generally longitudinally, shaft  30  having a knob  32  at a first end that extends from a bottom of the handle, a second end of the shaft having gearing so that turning knob  32  in a first direction rotates the track out of a longitudinal axis of the head to an open position, and turning knob  32  in a second opposite direction of rotation rotates the track back into a longitudinal axis of the head in a closed position, as will become clear in subsequent figures. Typically, although not necessarily, the slidable engagement of the bed  28  with the track  24  is based on the bed  28  and track  24  having complementary surfaces that are mated together to slidably engage bed  28  with track  24 . 
     In the open position bed  28  and bristles  26  can be slidably removed from track  24  and replaced with a new bed and bristles, whereas when track  24  is aligned with the longitudinal axis of the head in a second, closed, position, the bed is locked into place by a tip  44  of head  20 . In order to lock bed  28  by tip  44 , various embodiments known to those skilled in the art may be envisioned including a frictional fit or a snap connection wherein bed  28  (or track  24 ) has a rounded upper portion and tip  44  has an indented area. In addition, toothbrush  10  can be made so that tip  44  is formed of a slightly flexible material. In an alternative embodiment tip  44  can be lifted slightly in a direction away from handle  12 , such as by introducing a spring or other element, in order to allow track  24  to swing outwardly to the open position. 
     In a preferred embodiment track  24  is generally U-shaped, as may be seen more clearly in FIG.  2 . Also in a preferred embodiment head  20  is bent at an angle with respect to the handle  12 , the bend occurring in the region of the neck  22  in order to facilitate a more comfortable brushing position for a user. 
     It will be recognized by those skilled in the art that many varieties of gearing can be contemplated which would convert a rotary motion of knob  32  into a second substantially perpendicular rotation of track  24 . Advantageously such gearing will create a mechanical advantage between the knob and the track, which will also prevent unintentional rotation of the track by forces acting directly on the track. 
     One such simple gearing arrangement is illustrated in FIGS. 2 and 3. Shaft  30  is illustrated as a flexible shaft capable of transmitting rotatory motion through curves, as is known in the art. Shaft  30  is connected at a first, lower, end to knob  32  and at a second, upper, end to a worm gear  36 . Worm gear  36  further engages a spur gear  38  which is connected to track  24 , shown in phantom in FIG. 2, a partially broken away view of the mechanism as seen from the back or non-bristle side of the brush, via an axle or short shaft  40 . It will be appreciated from an examination of FIG. 2 that a clockwise rotation of knob  32  as seen from the bottom of brush will result in worm gear urging spur gear  38  in a counter-clockwise direction as seen from the rear view of FIG. 2, or clockwise as seen from the front of the toothbrush. In order to facilitate gripping and turning of knob  32  by a user, the knob is provided with knurls or indentations  42 . 
     It will be appreciated by those skilled in the art that other arrangements of gearing will be possible to a achieve the objective of translating rotatory motion of the knob to an appropriate rotation of the track. By use of a second spur gear for example (not shown), a rotatory motion of a worm gear attached to shaft  30  could be translated to axle  40  without the requirement of a flexible shaft. However, this arrangement would require additional gears relative to the illustrated embodiment. 
     Worm gear  36  may also be seen in partially broken away side elevation FIG. 3, with the spur gear omitted for clarity. Short shaft or axle  40  may however been seen more clearly penetrating the casing of toothbrush head  20  to join the spur gear to track  24 . A projecting lip  44  or tip  44  or stop  44  on head  20  may also be seen in this view, whose function will become apparent below. 
     It will be appreciated that alternative sources of rotation, or rotators, may be situated at a lower end of hollow handle  12 , other than a manually actuated knob. For example a small electric motor provided with a reversing switch (not shown) may be employed to rotate shaft  30 , and hence track  24  in a manner similar to manual operation. The mechanical advantage provided by worm gear  36  and spur gear  38  will allow a motor with modest torque to accomplish this function. 
     It is also contemplated by the present invention that in an alternative embodiment not drawn, the rotator or knob  32  is located other than at the first end of shaft  30 . For example, knob  32  may be located in the middle of handle  12  in any convenient manner accessible to the user and fitted on to shaft  30  so that rotating knob  32  turns shaft  30 . In case knob  32  is in the middle of handle  12 , to secure the part of the handle  12  below knob  32  to the rest of the device, there would be added a bridge of plastic (or of whatever the material the handle  12  is made of) or any other well known suitable means connecting the part of the handle above the knob with the part of the handle below the knob. With respect to this alternative embodiment, shaft  30  need not extend beyond rotator/knob  32 . Furthermore, since knob  32  may not be at the first end of shaft  30 , it is useful to describe the second end of shaft  30  as the end that is nearer to applicator section  18  than the first end of shaft  30 . 
     A method for interchanging bristle beds on a toothbrush  10  constructed in accordance with the invention is shown generally in FIGS. 4 a - 4   e . FIG. 4 a  is a side elevation generally showing a toothbrush with a bristle bed in place, corresponding with FIG.  1 . In FIG. 4 b  a rotation of knob  32  by a user is generally indicated by a bold circular arrow (not separately designated) in a vicinity of the knob, the rotation being in a clockwise direction as seen from a bottom of the toothbrush (which can be partially seen in the perspective view of FIG.  1 ). Accompanying this rotation, as will have been understood by examination of details in FIG.  2  and FIG. 3 showing the mechanism, will be a clockwise rotation of track  24  with attached bristle bed  28  rotation as seen from the front of the brush, as shown in FIG. 4 b . The rotation of track  24  is generally indicated by a bold arcuate arrow (not separately designated) shown in a vicinity of the bristle bed. 
     It will also be understood from FIG. 4 b  that upon rotation of the track  24  the bristle bed  28  is freed from the locking effect of lip  44 , and is therefore free to be slid off the track  24 , as shown in FIG. 4 c . In FIG. 4 d  a new bristle bed  28 ′ is similarly shown being mounted on the track, and, following a reverse, counterclockwise rotation (not shown) of knob  32  by the user, reversing the effects of disassembly, the bed  28 ′ is locked into place by interference with lip  44 , thus preventing unintentional disengagement and readying the brush for renewed use, as shown in FIG. 4 d.    
     Further variation or embellishments of the basic method will be readily understood, and are not specially illustrated. For example, it will be apparent that new bristle head  28 ′ may be enclosed in an individual flexible sanitary package (not shown), similar to the familiar adhesive bandage strip, which may be torn open at time of use. Through tearing off one end of such a package and grasping the bed through the package walls, bristle bed  28 ′ may be urged upon track  24  without fingers contacting the new bristles. Similarly, bristle beds may be packaged in multiple units, as in a box, in such a way that the track can be induced to engage an available bristle bed by manipulation of the box and brush, without necessity of fingers contacting the fresh bristles. In terms of removal of the old bed, it will be understood that in an open position, as shown in FIG. 4 c  an old bristle bed may be removed and projected into a waste receptacle by a flicking or whip like movement of the brush without the user contacting the soiled bristles. 
     It is thus apparent that the invention allows a replacement of a soiled or worn bristle bed by a new bristle bed without cross contamination of the new bristles by the old, or a necessity of user contact with either the old soiled bristles or the new sanitary bristles. The invention is thereby ideal for rendering a routine hygienic replacement of toothbrush bristles both practical and enjoyable, and unlike anything available in the prior art. The invention represents a method and device for the routine hygienic replacement of toothbrush bristles for the elimination of bacteria which is both easy, convenient, fun, and encourages frequent replacement. 
     It is to be understood that while the apparatus of this invention have been described and illustrated in detail, the above-described embodiments are simply illustrative of the principles of the invention. It is to be understood also that various other modifications and changes may be devised by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof. It is not desired to limit the invention to the exact construction and operation shown and described. The spirit and scope of this invention are limited only by the spirit and scope of the following claims.