WO2001021035A1

WO2001021035A1 - Automatic pressure release toothbrush ii/iii

Info

Publication number: WO2001021035A1
Application number: PCT/US2000/022396
Authority: WO
Inventors: Ingram S. Chodorow; Scott Salmon; Steven Bellafatto
Original assignee: Placontrol, Inc.
Priority date: 1999-09-17
Filing date: 2000-08-15
Publication date: 2001-03-29
Also published as: AU6908400A

Abstract

An automatic pressure release toothbrush has a handle (11) with proximal and distal ends, a head (12) having a longitudinal axis (12A) and having bristles (13) extending generally in a first direction transverse of this longitudinal axis, and a hinge (14) connecting the head (12) to the distal end of the handle (11). When excessive force beyond a predetermined magnitude is applied to the head (12), the head (12) automatically moves to a displaced position wherein the toothbrush is temporalily unusable until the head (12) is returned to its normal position.

Description

AUTOMATIC PRESSURE RELEASE TOOTHBRUSH II/III

PRIOR APPLICATIONS UPON WHICH PRIORITY IS CLAIMED

This application is based on and claims priority of

United States Provisional Application Nos.

60/154,418 filed 9-17-99 60/192,693 filed 3-28-2000 60/201,565 filed 5-1-2000 and Utility Application, Ser. No. ; filed 5-31-2000, all pertaining to automatic pressure release toothbrushes.

BACKGROUND

1. Field of the Invention

This invention is in the field of toothbrushes, particularly typical toothbrushes where the user applies oscillating, linear, circular and other motions along with varying amounts of axial pressure of the bristles on the tooth and gum surfaces.

2. Background of the Invention

It is well accepted that regular brushing of the teeth along with flossing, dental examinations, and other appropriate care is essential to maintain healthy teeth and gums or to at least to minimize deterioration. In this regard hundreds of millions of toothbrushes are used regularly throughout the world.

A variety of new toothbrush designs have been periodically introduced into the oral care market with new features that improve performance or ergonomics. Some of the many new designs included different angles of the head and/or the bristles, different tuft designs, varying hardness and stiffness of the bristles, and even wear markers either on the handle or in the bristles to indicate fatigued bristles and to signal the time to replace the toothbrush. Also, in recent years mechanized toothbrushes have been introduced which move bristles in various circular or transverse motion patterns, and also axially at extremely high speeds.

Many of these toothbrushes represented significant advances. However, one particular issue or problem persists and has led to proposed solutions which run the gamut of extremes. This is the issue of how stiff and/or hard- the bristles should be to adequately clean the teeth without damaging the enamel surface of the teeth.

About twenty-five years ago hard or stiff bristles were preferred, because soft and medium bristles were considered too weak to achieve adequate cleaning. Makers of brushes with natural bristles proclaimed their products safer and superior to nylon and other plastic bristles. More recently, soft bristles have been generally considered by dentists as the only safe bristles to use to avoid both enamel and gum damage.

Numerous other approaches have been tried and implemented seeking to reduce the damage done to teeth and gums and seeking to reduce the risk caused by excessive pressure from the bristles of the toothbrushes, but all have missed the point, as explained below.

One attempt included a spring in the neck between the handle and the head. Excessive force on the bristles caused the head to bend; however, the spring caused the head and bristles to apply a greater force against the teeth, the more the head bent. The result was worse than if a plain toothbrush with no spring neck were used. Another approach was to alter the bristles or to make them softer. However, users rarely know what is the correct pressure level to apply. So, whether bristles are soft or too soft or hard or medium, the user is still likely to apply the wrong pressure.

A brush might even have a light or sound alarm when the force is excessive, but this does not prevent the user from continuing to brush.

The debate remains unresolved as to which of the above toothbrushes is best; however, a vast number of people continue to suffer from worn enamel and/or bleeding or sore gums because of the toothbrushes or brushing techniques they use. Thus, none of these dental developments has adequately solved the above discussed problems of damaged enamel and gums caused by .the toothbrushes or brushing techniques.

SUMMARY OF THE INVENTION

The present invention (a) recognizes the failure of the oral care industry to develop a toothbrush with ideal bristles that are best or safest with regard to enamel and/or gum damage, and (b) proposes a totally different approach that solves the problem and is applicable with all or most existing toothbrushes .

The issue the present invention addresses is excessive pressure applied to the teeth and gum surfaces during brushing. All of the attempted solutions with different bristle materials, tuft patterns, varying stiffness and handle ergonomics fail to deal with the fundamental fact that users of toothbrushes apply by their own hands uncountable variations in pressure of the bristles onto their own teeth. Not only does each person exert a different force, each person will vary his or her force depending on the angle of the hand holding the brush as different areas of the mouth are brushed. So, a medium bristle may be applied very hard in some areas, or a hard or medium bristle may be pressed inadequately to properly clean. There is no way to effectively teach people exactly how hard to press the tuft or bristles against the teeth and gums, and because of varying angles of toothbrushes and arm and finger positioning any attempted pressure level could not be maintained constant anyway.

The new toothbrush invention in a first preferred embodiment includes a hinge between the handle and the head. When light to moderate pressure is applied this new toothbrush performs like other toothbrushes; however, when the pressure of the bristles on the teeth is excessive, according to a predetermined safe level of pressure, the hinge automatically releases the head causing it to bend backward, in a direction away from the teeth.

The hinge has a preset pressure threshold. In typical toothbrush use a person holds the handle and through the handle and the head at the end thereof, applies pressure of the bristles onto the teeth. It is basic mechanics that the pressure applied by the bristles is experienced by the head of the toothbrush and by the hinge to which the head is coupled. When this pressure reaches the predetermined unsafe threshold level in the new toothbrush, the hinge gives way, and in a preferred embodiment snaps to a new position whereby the head is in an awkward and unusable position, and the user is forced to stop brushing and stop applying the excessive pressure. This alteration of the toothbrush structure remains until the user manually corrects it by snapping or otherwise pushing the head back into its original position.

This elegant and simple solution automatically prevents excessive force from being applied to the teeth and gum surfaces, and more importantly, teaches the user what excessive pressure feels like so that an excessive level of force can be avoided and a correct level learned and maintained. The new hinge can take a variety of forms, one being a bi-stable spring having two positions where the spring is integrally molded with the toothbrush handle and head. This hinge is a type of toggle mechanism whereby the head is biased to go to and remain in either a first position (normal position) or in a second position which is intended to be so awkward that it is essentially un-usable. The transition from first to second position occurs when the user presses the bristles too hard against the teeth. This force is transmitted to the head and thence to the hinge which automatically reverses its configuration and drives the head to said second position.

In a second embodiment the hinge uses a rectangular elongated strip of resilient plastic compressed in the longitudinal direction until it bows and functions as a bistable spring; in a third embodiment uses an elongated spoonlike or concave spring of resilient plastic; in a fourth embodiment uses a two-part hinge with a bi-stable spring between these parts.

In the above configurations the spring will, when excessively stressed, snap to an inverted stressed configuration. Application of such excessive force by the user to the bristles and thence to the toothbrush head will bend the head which is firmly connected to said top end of the hinge that snaps to its second position. Subsequently, the head is either manually forced back to its first, normal position, or it can be designed to return automatically after a predetermined time period.

In a variation the hinge would resist bending until a threshold force were applied and then would release the head from being held in said first position and leave it floppy or loosely attached to the handle. The toothbrush remains essentially unusable until the user manually returns the head back to said first position where the head is maintained until excess force is again applied. This return automatically activates the hinge spring to its first condition wherein it biases the head to stay in said first position until the force on the head again becomes excessive causing the head to snap, to said second position.

Thus, the hinge experiences a bending force until the applied force exceeds the preset safe-limit, at which time the hinge releases the head to flop or bend, pivot or rotate to an unusable position. The head may remain freely movable in a zone of full or partial displacement, or it may latch in a specific displaced position. In either case, the head may be manually returned to its normal, operable position where it will latch or otherwise be restrained to remain until excessive force displaces it again.

A third set of embodiments utilizes a spring element in combination with a hinge to establish a toggle mechanism. In contrast to the first set of embodiments where the spring itself was bi-stable, having two normal but different positions, this third set of embodiments uses a normal compression, extension or bending spring, which has a single relaxed state and a single stressed or deflected state, in combination with a toggle type hinge having a set of two different stable states, as in a traditional two-position toggle mechanism.

A fourth set of embodiments has no positional change by the head relative to the handle, but instead one or more parts of the head are displaced relative to one or more other parts of the head or to the handle.

In a fifth set of embodiments, relative to the handle the head is movable to an awkward or unusable position, and the resistance to movement is a spring or friction force that resists up to the threshold level of force and then collapses.

Stated differently, this invention is a new toothbrush which protects the user's teeth and gums by automatically deforming to an inoperative configuration whenever too much pressure is being applied by the toothbrush bristles to the teeth and/or gums . This new toothbrush has an initial operative state or configuration with the head extending generally axially from the handle or inclined slightly forwardly or rearwardly, and an inoperative state where the head is inclined rearwardly so far that a user would find it awkward or impossible to use. In every embodiment the head of the toothbrush has a normal orientation relative to the handle, and this head moves or bends or pivots, when pressure on the head exceeds a predetermined threshold level, to another position or orientation wherein continued brushing is awkward or impossible. In some embodiments the second position is a specific orientation where the deflected head remains until it is manually moved back to its normal orientation.

In variations of these embodiments, once the head is pushed by a force beyond its latch point, it may be released (a) to "flop" freely between said release position or (b) to arrive at some other limiting position. Such limiting position might be pivoted 10°, 20°, 30°, etc. or even 180° from the original position. Normally, the head will have to move a very small amount during the release phase before it either flops or moves to a designated second position.

The amount of pressure or force necessary to make the head release or "pop" from its normal position usually will be determined during manufacture. The preferred range is from about 2-12 ounces, but may be more. One particular embodiment has the release pressure set at about 7 ounces.

In another embodiment the user of the toothbrush can vary the release force required. This could be done by a dial or knob which affects the pivot coupling between the head .and the handle. For example, one spring-biased projection on the head could pass over another fixed projection on the handle. The fixed projection could be adjusted or moved so it projects further into the path of the spring-biased projection that moves past the fixed projection. Thus, the spring element would have to be further deflected to allow the spring-biased element to pass by the fixed element. Such adjustment could be available to the ultimate user, or could be done in the factory so that the toothbrush has a pre-set force release level. Many other structural arrangements are possible to vary the pressure release force level. One could be merely to increase frictional resistance between the intersecting projections. Other structures without such projections are also feasible.

Some embodiments will be of injection molded plastic, such as polypropylene. In many embodiments the entire product, namely the handle, head and the pivot coupling and release element will be one single contiguous molded product.

When this toothbrush is made as a single, contiguous injection molded product the integral pivot area could be a well-known living hinge, which is strong and reliable to flex a very great number of times before failure. With this product the bristles may be included in the basic injection molding or will be attached to the head.

In many of the embodiments shown the head breaks away or bends essentially only in a rearward direction, namely the direction opposite of the direction in which the bristles extend. Bristles may be oriented in multiple angle directions, but generally they are connected to and extend from a front face surface of the head. Thus, these heads bend in a direction opposite the frontward direction of said front face.

As regards the orientation of the head upon breakaway, one preferred embodiment has a limiting shoulder on the handle or in the pivot or hinge structure to limit the head from flopping more than a set amount from the original normal position. In one embodiment this limit is set at about 30° from the normal position, but it could range from 10-90° depending on the amount of awkwardness to achieve during breakaway.

A major benefit of this invention is that of a teaching tool. Users will discover that as they apply excessive pressure the toothbrush will deform and become useless. Eventually, users will learn how much force/pressure is allowed before breakaway. This education may not be so easy, because within the user's mouth the toothbrush is used in different orientations to reach different teeth; also the user's wrist, fingers and arm must be altered almost continuously to manipulate the brush to near and far teeth, upper, lower, etc.

Until users learn (or even if they never learn) the correct pressure limit, this new toothbrush will still "automatically" release and thus protect the enamel of the teeth and the gums from excessive pressure and abrasion.

Preferred embodiments of this invention will be described below with reference to the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Group I

Fig. 1 is a right side elevation view partially in section of a first embodiment of the new invention,

Fig. 2 is a rear elevation view thereof,

Fig. 3 is a front elevation view thereof,

Fig. 4 is a fragmentary sectional view taken along line 3-3 in Fig. 2,

Fig. 4A is similar to Fig. 4 but shows the hinge in activated position,

Figs. 4b-4d show the toothbrush and spring in a succession of positions as the spring bows from right to left,

Figs. 4e-4g show enlarged views of the spring of Figs. 4b-4d,

Figs. 4h and 4i show cross-sections of the spring in Figs. 4e and 4g respectively of the spoon type bi-stable spring,

Fig. 4j shows a third embodiment of bi-stable spring showing its two stable positions. Group I I

Figs. 5-10 show a second embodiment of the same invention, namely a spoon shape bi-stable spring, where:

Fig. 5 is a side elevation view similar to Fig. 1 but with the hinge activated and the toothbrush head moved to its second position,

Fig. 6 is a schematic side elevation view similar to Fig. 1 but of a second embodiment,

Fig. 7 is a rear elevation view of Fig 6,

Fig. 8 is a front elevation view of Fig. 6,

Fig. 9 is a fragmentary side view taken along line 9-9 in Fig. 8,

Fig. 10 is a fragmentary front and right side perspective view of the toothbrush of Figs. 6 and 8,

Fig. 10A is a front elevation view of Fig. 10, Group III

Fig. 11 is a fragmentary right side elevation view of a third embodiment of the new toothbrush with a multiple component hinge,

Fig. 11a is an exploded perspective view of the hinge of Fig. 11, and Group IV

Fig. 12 is a fragmentary side elevation view of a fourth embodiment showing it in two positions. Group V

Fig. 13 is an elevation view in section of a fifth embodiment showing a spring latch hinge. Fig. 14 is similar to Fig. 13, with the latch released and the head starting to pivot backward.

Figs. 15-18 show the toothbrush of Figs. 13 and 14 in a succession of pivoted states.

Figs. 19-22 are similar to Figs. 15-18, but with the spring portion of the latch reversed. Group VI

Figs. 23 and 24 show a further embodiment of spring latch in closed and released positions respectively. Group VII

Figs. 25 and 26 show a bi-stable hinge with a central spring that is compressed.

Figs. 27 and 28 show a bi-stable hinge with a central spring that is stretched.

Figs. 29 and 30 show a bi-stable hinge with a pair of springs that are compressed.

Figs. 31 and 32 show a bi-stable hinge with a pair of springs that are bent to a curved state.

Figs. 33 and 34 show a bi-stable hinge with a central spring that is compressed.

Figs. 35 and 36 show a bi-stable hinge with a central spring that is stretched.

Figs. 37 and 38 show a bi-stable hinge with a pair of springs that are stretched. Group VIII

Figs. 39-42 show a further embodiment with a rotary hinge and spring finger as a latch. Group IX

Figs. 43 and 44 show a further embodiment where the latch is in the head of the toothbrush.

Figs. 45 and 46 show a variation of this embodiment where the latch is in the toothbrush head. Group X

Fig. 47 shows a further embodiment of release hinge.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The first embodiment 10 of the new toothbrush is seen in Figs. 1-3, 4 and 4a-4i consisting of a handle 11, head 12 with bristles 13 and a hinge 14 connecting the head and handle. Figs. 2-4 show further details of the hinge 14 comprising a central strip 15 having top and bottom ends 15T and 15B respectively and intermediate arch or bow 15C.

Fig. 3 shows the hinge is essentially three parallel strips, namely central spring strip 15 and adjacent outer strips 16. Figs. 4 and 4a show further details of hinge 14 where the arch or bow spring element 15 is connected by its tip part 15T to the head 12 and by its bottom part 15B to the handle 11. This arch has a bowed configuration because it is in axial compression while the adjacent elements 16 are in tension. The bow is a bi-stable spring which attains a first stable condition or position shown in Fig. 4 with the longitudinal axis 12A of the head angled slightly to the left of the longitudinal axis 11A of the handle, and a second stable condition 18 shown in dotted lines in Fig. 4a with the spring element 15 at 15a bowed to the left and the head inclined to the right. This results from a force applied in the rightward direction to the head as indicated by arrow 19.

Most toothbrushes have the head either coaxial with the handle or angled forward as seen in Figs. 1 and 4; the rearward angle of the head per longitudinal axis 4R in Fig. 4a results in a toothbrush with an awkward configuration which is essentially unusable until the head is returned to its normal position .

Fig. 4b and 4c show the succession of positions of the spring 15 from being bowed to the right to the left. Fig. 4d shows the spring alone bowed to the left; Figs. 4b and 4c show the left side tension element 16. Figs. 4e-4g show further details of the spring element through its transition from right to left bowing and the corresponding angular change of the head 12 from left to right. Figs. 4h-4i show the cross-sections of Figs. 4e and 4g respectively whereby the concavity is reversed.

Figs. 5-10 illustrate the second preferred embodiment which differs from the first embodiment primarily in the configuration of the hinge and spring element. Similar structural elements of the handle, head and bristles will have the same reference numeral designations and new structure will have new reference numbers.

In this second embodiment 40 the handle 11 and head 12 are essentially the same as before. The hinge 41 is an elongated concave or spoon shaped elastic element 43 seen most clearly in Fig. 10. Fig. 8 shows how the center area 43c of the dish is thinner than the top and bottom ends 43T, 43B respectively. This dish has a thickness of about 0.02 inches on the side edges, about 0.03 inches at the center of the dish, and 0.05 inches at the top and bottom ends where the spring element is thicker where it joins the head and handle respectively. As with the first embodiment, excess pressure on the head is translated to the top end 43T of the concave spoon-shaped spring which eventually snaps to inverted convex shape, thus directing the head to its new angled position

This second embodiment has the advantage of simplicity of structure and economy of manufacture in addition to operating simply and effectively. As with the earlier-disclosed embodiment the entire toothbrush handle, hinge and head can be molded in a single cavity in a single molding stage. Obviously, these toothbrushes will be manufactured in typical high-speed multi-cavity injecting molding machines, with the bristles incorporated into the toothbrush head in a standard manner.

As seen in Figs. 11, 11a and 12, the third embodiment 50 follows the same principles of operation of the prior embodiments, but utilizes a multi-component hinge . In this structure the handle 61 defines at its top end a hinge yoke 62 having side walls 63 and a central pivot axis 64. The head 65 has the same pivot axis 64 and a pivot axle not shown through said axis 64.

At the bottom end 65B in Fig. 11A, the head has a detent or spring biased ball 66 that extends outward and engages recesses or holes 67a, 67b in the yoke. When ball 66 is in recess 67a the head is inclined to the left in its position for normal operation. The head bottom end 65B then pivots within yoke 62, and when the bristles are pressed excessively hard on the teeth or gum, force is applied in the direction of arrow 68 which pivots the head clockwise about the handle until ball 66 engages recess 67b. In this configuration the toothbrush would be unusable, and thus the teeth enamel would be protected from further excessive abrasion.

In this embodiment the detent is to release the head to pivot only when the force per arrow 68 is sufficient to overcome a pre-set threshold resistance limit of the detent. If the pre-set threshold is set at six ounces, then any force greater than six ounces will cause pivoting of the head. A variation of the embodiment of Fig. 11 will have a detent 66 as shown, but will have only one recess 67a. When the detent is in recess 67a the head will be in the initial and proper orientation relative to the handle. When the head is forced out of this position and the detent is driven out of recess 67a, the head will be free to "flop" backward. In one version there will be a stop to limit the backward movement of the head. In either case the head will bend but not snap to an unusable orientation until it is manually pushed back to its initial position. In these embodiments the head either remains in its initial position until the threshold force is exceeded, or the head flexes proportionately to the applied force but does not release until the threshold is reached.

Fig. 12 shows a variation where there is the same yoke 62 and tongue 65B which have the same pivot axis 64; however, instead of spring action by the ball detent, there is a flexible flat spring 69 which flips or snaps from being concave facing left to being concave facing right when the head pivots per arrow 70 from phase (a) to (b) , similarly as the spring in the first embodiment disclosed herein.

Figs. 13-18 illustrate the fourth embodiment, including handle 101, head 102, bristles 103, handle distal end 101P, head proximal end 102P, projection 106 extending from head 102, catch 107 extending from handle 101, spring arm 102T which carries projection 106, and relief space 108 that is closed when arm 102T is displaced to the left.

This is a latched hinge wherein projection 106 is lodged beneath catch 107. Force F pushes head 102 in counterclockwise direction. When the force exceeds a predetermined amount of about 2-10 ounces, the catch releases as seen in Figs. 14 and 17, and the head pivots and flops freely to full tilt as seen in Fig. 18. During release of the catch the projection 106 and the terminal end 102T of the head from which the projection extends move laterally to the left, and the relief space 108 is momentarily closed. The end 102T thus functions as a resilient spring coupling. When the head 102 is inclined as seen in Fig. 18 or is floppy because it is loosely residing in the area of incline from Fig. 17 to Fig. 18, the toothbrush is inoperable or certainly too awkward to use.

This toothbrush can be returned to operable configuration merely by pushing/pivoting the head back to the position seen in Figs. 15 and 16.

Figs. 13 and 14 show enlarged detailed views of the shapes of the two interfering projections 106 and 107 from Figs. 15-18. These shapes can be varied so that, for example, a greater force is required to cause break away than is required to re-set the released head back to its normal position. As seen in Fig. 13 there is a trip force to cause release. The trip force corresponds to a force transfer point, namely the surface of the spring arm which engages a fixed surface of the handle

In Fig. 14 can be seen a different force transfer point which is in play when the head is reset. The angles of these surfaces can be varied and/or the distances from the pivot point and/or the surface roughness to vary the ultimate force required to trip and release.

Obviously, the neck of the spring arm can be varied to affect the spring force. This neck may be wider, thicker, perforated, etc. It can be positioned differently, and the material of the spring arm and/or the neck can be selected to achieve the desired result.

As noted in the prior provisional applications, some embodiments will be of injection molded plastic, such as polypropylene. In many embodiments the entire product, namely the handle, had and the pivot coupling and release will be one single contiguous molded product.

Thus, when the force threshold is reached, .the toothbrush structure will automatically and quickly fail, and thus protect the user' s teeth and/or gums from excessive brushing pressure and/or abrasion.

Figs. 19-22 illustrate a fourth embodiment that is similar to Fig. 1 but differs in that the relief opening 115 at the proximal end of the head faces the back or rear surface of the head instead of facing the front or bristle side of the toothbrush. In Figs. 19-22 the handle 101, head 102 and bristles 103 have the same reference numbers as before, but other structures will have new sequential numbers. Thus, the hinge 113 has pivot pin 114 near the rear surface, as compared to pin 105 in Figs. 15-18 which is near the front surface. Also, in Figs. 19-22 the V-shape relief space 115 faces the rear surface of the head, and it closes momentarily when the head pivots counterclockwise when Force F exceeds the predetermined threshold level . Figs. 23, 24 show a fifth embodiment 200 with a pair of bendable arms 201, 202 straddling a central projection and catch mechanism, 203, 204. This latch or catch mechanism is designed to release or fail when force F exceeds the predetermined safe limit. This embodiment, like many others, is a single injection molded unit of handle, head and releasable hinge. The plastic is selected from materials well known in the art, as are the bristles, and mode attaching them to the heads. The projection and catch could be reversed.

In this latch type release as shown the small projection 203 in the handle engages a corresponding recess, in the central projecting finger extending from the proximal end of the head. This projection could be a spring detent or merely an integral element co-molded with the handle. These projection, recess, hinge elements can have their dimensions and strength varied to establish the desired release or trip force to allow flop-over and reset. Also, shoulders or other stop means can be incorporated to allow flop-over in one or both directions and to limit flop-over to a desired amount, such as about 30 degrees from normal.

Figs. 25-28 show a sixth embodiment 117 with similar handle 101, head 102 and bristles 103, but with a different coupling 118 in the form of a circular ratchet. As seen in Fig. 27 the head part 102 extends to the right and terminates in round central shaft 119 with projection 120. The handle 101 extends to the left into a ring-shaped collar 121 situated around said shaft. The collar 121 has a set of teeth 122 that engage projection 120 as the head pivots about the handle. The teeth may be uniform or set to achieve a uniform resistance as the head is pivoted and projection 120 moves from one tooth to another. In this case the user can set the angle of the head by rotating the head relative to the handle, and use the toothbrush until force F exceeds the predetermined safe limit. Then the head will rotate all the way to rear stop 123 where the inclination will be so great that the toothbrush will be inoperable as seen in Fig. 28.

In this embodiment the shaft 119 is molded as part of the head, and the collar 121 is molded as part of the handle, and the parts are secured together in rotatable coupling structure known in the art. Obviously, the pin 120 and teeth 122 could be reversed, namely to put the pin on the collar and the teeth on the shaft. This reversal concept could easily be applied to the two above-described embodiments, where the projection and catch could be reversed.

These rotary coupling embodiments include an outward radial tooth on the central shaft and a series of inward teeth on the housing or collar, it may be preferred that the first inward tooth have length to establish the desired release force for breakaway, and that the remaining teeth are shorter and merely brush against the outward tooth as the head flops, these remaining teeth producing a mild audible sound to further notify the user of the condition of the head. Various other audible sound producing structures are possible.

Also shown in Fig. 27 is a front stop 124 which limits forward rotation or pivoting of the head.

Figs. 29, 30 show a seventh embodiment 130 with a coupling 131 between the handle 101 and the head 102. The coupling comprises first arm 132 that bends about bend line 133 and a similar second arm 134, and between them spring 135 which has a relaxed state as seen in Fig. 29 where the toothbrush has its operative configuration. Upon application of force F the head pivots downward or clockwise. The spring is designed to give way upon the application of an unsafe force on the bristles of about 5 ounces or other force amount as may be determined. Whenever that happens, the head is moved to the inoperative position shown in Fig. 30. Thus, when head 102 is pivoted rearward (opposite the direction of the bristles) this spring is stretched momentarily until the head flops to its deflected position at which time the spring again relaxes. The shoulders opposite the hinge pivot point establish a stop to limit flop- over of the head to about 30 degrees from the normal position.

Figs. 31 and 32 show a further embodiment where the central spring 140 of undulating shape is stretched when force F is excessive, with a similar result as in Fig. 30. The hinges used in the bendable arms are typical "living hinges" molded integral with and part of the handle and head.

Figs. 33 and 34 show a variation with a pair of springs 150, 151 which stretch by extending or straightening when flexed. The springs straddle a central hinge arm 152.

Figs. 35 and 36 show a further embodiment 160 with a pair of bendable arms 161, 162 and a pair of springs 163, 164 which are oriented to bend about axes generally perpendicular to the longitudinal axes or plane of the handle. When force F exceeds the safe limit, springs 163, 164 collapse and bend outward into the convex curves seen in Fig. 36, and the toothbrush then has an inoperative configuration.

Figs. 37 and 38 show another embodiment 170 with a pair of arms 171, 172 straddling a stretch spring 173. This central spring is stretched during flop-over and returns to be less stretched and relaxed after flop-over. Also, this embodiment has two sets of hinge or pivot points. The head, arm, springs and handle are co-molded and the relief or bendable pivot areas 174, 175 are included and incorporated therein.

Figs. 39 and 40 show another embodiment 180 with a pair of bendable arms 181, 182 straddling a central, stretchable spring 183.

In all of these spring-pivot hinge structures it is preferred to co-mold the handle, head, hinge and spring as a contiguous integral injection molded unit. This reduces manufacturing and assembly cost and avoids having separate parts and places where toothpaste or other debris can lodge.

Figs. 41 and 42 show another embodiment 190 with a pair of arms 191, 192 each including a stretchable spring 194. The arms straddle a central bendable arm 193.

The new toothbrushes shown above may have the breakaway force level set in the range of 1 to about 12 ounces. The important feature is that the user' s teeth and gums are protected because when the force exceeds a predetermined safe level the toothbrush is disabled.

The new invention herein is the first totally different approach. Instead of altering the structure of the handle, head and/or bristles, this invention disables the toothbrush. The head pivots or bends or folds away to a configuration of toothbrush that is so awkward that it is inoperable .

From this, the user not only is protected from himself/herself, but is afforded repeated opportunities to learn what is the correct pressure level to use to avoid the breakaway disablement. This invention is applicable to a wide range of toothbrushes, with various bristle forms and constructions, various handles and heads, and even those with flexible parts.

In an eighth embodiment, as seen in Figs. 43-46, instead of the whole head bending or pivoting relative to the handle, one part of the head moves relative to another part, with the result as before, that the toothbrush has a changed form that is awkward or impossible to use, and the user must reset the moved part before brushing can continue.

For this embodiment the head may "breakaway" about a longitudinal axis of the head as illustrated in Figs. 43 and 44, or about a transverse axis extending across or through the head as seen in Figs. 45 and 46. Also, the handle could break away somewhere other than at its junction with the head; and also .the head can breakaway at a point other than along its central longitudinal or horizontal axis.

A ninth embodiment is shown in Fig. 47, represented schematically. Here, the head has a stem mounted to the handle for motion in all lateral directions or even circular or oscillating motion. The stem is mounted to maintain the head essentially erect, but movable if excess force is applied. At such time the head will incline to an awkward position and the device will be disabled.

All of these embodiments and other variations within the scope of this invention apply the principle of altering the position or orientation of the toothbrush head when excessive force is being applied by the bristles to the teeth or to the gums .

Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.

Claims

1. A toothbrush comprising a handle having proximal and distal ends and a generally central longitudinal axis, a head having proximal and distal ends and a generally central longitudinal axis, bristles secured in said distal end of said head, junction means joining said distal end of said handle and said proximal end of said head in a pivotable relationship, and latch means engaging said head and said handle, said latch means normally maintaining said head in a predetermined first position relative to said handle, said latch means automatically releasing said head to pivot relative to said handle when force of a predetermined magnitude is applied to said head in a direction generally transverse to said central longitudinal axis thereof.

2. A toothbrush according to claim 1 wherein, in said first position said head has a fixed position relative to said handle, and when said latch means is released said head is freely pivotable relative to said handle and thus inoperative as a practical toothbrush.

3. A toothbrush according to claim 1 wherein said bristles extend in a generally forward direction, and wherein said head is pivotable in a direction generally opposite said forward direction between said first position and a second position rearward of said first position, and wherein said head has a fixed position relative to said handle, and when said latch means is released said head is freely pivotable between said first position and said second position.

4. A toothbrush according to claim 2 wherein, in said first position said central longitudinal axis of said head defines an angle in the range of about 0-30 degrees with said central longitudinal axis of said handle.

5. A toothbrush according to claim 2 wherein said head proximate end comprises a first part and said handle distal end comprises a second part, and wherein said latch means normally urges said second part into coupling engagement with said first part, and wherein one of said first and second parts is resiliently bendable when said force is applied to said head to cause said release of said latch means to allow said latch means to be released.

6. A toothbrush according to claim 5 wherein said first part is a projection and said second part has shape adapted to engage said projection.

7. A toothbrush according to claim 1 wherein said junction means comprises at least one thin flexible hinge strip joining said head and said handle and at least one spring element extending between and engaging said head and said handle .

8. A toothbrush according to claim 1 wherein said junction means comprises a hinge coupling said handle and said head.

9. A toothbrush according to claim 8 wherein said handle and head are separate parts, and said hinge comprises a pin extending between and engaging said distal end of said handle and said proximal end of said head and extending generally perpendicular to said central longitudinal axes thereof .

10. A toothbrush according to claim 1 wherein said handle, head and junction means all comprise a single contiguous injection molded product.

11. A toothbrush according to claim 6 wherein said handle, head and junction means all comprise a single contiguous injection molded product.

12. A toothbrush comprising a handle having proximal and distal ends and a generally central longitudinal axis, a head having proximal and distal ends and a generally central longitudinal axis, bristles secured in said distal end of said head, junction means joining said distal end of said handle and said proximal end of said head in a bendable relationship, and latch means comprising first and second elements respectively on said distal end of said handle and said proximal end of said head, said first and second elements normally coupled to each other and maintaining said head in a predetermined first position relative to said handle, said first and second elements being automatically releasable from each other to permit bending of said head relative to said handle when force of a predetermined magnitude is applied to said head in a direction generally transverse to said central longitudinal axis thereof.

13. A toothbrush comprising a handle and a head with a front facing surface and bristles secured in said front facing surface, said head being bendable in a direction rearward relative to said front facing surface from its normal orientation relative to the handle when a force greater than a predetermined threshold level is applied to the head in said rearward direction.

14. A toothbrush comprising a head with bristles, first ends of which are embedded in the head and opposite ends extending in a general first direction, a handle, and a neck connecting said head and said handle, said head having a normal position relative to the handle, said neck being bendable from said normal position backwards in a second direction generally opposite said first direction when force exceeding a predetermined threshold level is applied to said head.

15. A toothbrush according to claim 14 wherein said head when moved in said second direction is moved to a second position inclined from said normal position by at least 20D.

16. A toothbrush according to claim 15 further comprising biasing means coupled to said head and said handle and applying a force in the range of 2 to 12 ounces urging said head to said normal position, said biasing means comprising a spring having bi-stable characteristics whereby application of a force greater than said predetermined threshold force in said second direction causes said biasing means to reverse and apply its force in said second direction, thus driving said head to said second position.

17. A toothbrush according to claim 16 wherein said spring always urges said head into one of said first and second positions .

18. A toothbrush according to claim 17 wherein subsequent application of a force greater than said predetermined threshold force in said first direction causes said biasing means to again reverse and apply its force in said first direction, thus driving said head back to said first position.

19. A toothbrush according to claim 16 wherein said bi-stable spring comprises a central strip generally parallel to said handle axis and two tension strips adjacent and generally parallel to said central strip, said central strip being resilient and bowed in compression, said tension strips extending generally axially between said handle and head and being in tension due to said spring biased to unbow .

20. A toothbrush according to claim 19 wherein each of said tension strips is bendable .

21. A toothbrush according to claim 16 wherein said bi-stable spring comprises an elongated resilient dish-shaped element having a generally concave configuration, said bi-stable element being in compression and having one end rigidly extending from said head, said tension strips extending generally axially between said head and handle.

22. A toothbrush according to claim 21 wherein each of said tension strips is bendable .

23. An automatic pressure release tooth brush comprising a handle with a central longitudinal axis, a head with a central longitudinal axis and with bristles extending generally in a first direction, and a hinge connecting said handle and said head, said toothbrush when used has said bristles urged in said first direction against a user's teeth thereby applying a force on said head in a second direction generally opposite of said first direction, said head being movable about said hinge relative to said handle, said hinge having two positions, namely a first position where said head longitudinal axis is within a range of 0 to 20° of said handle longitudinal axis in one direction, and a second position where said head longitudinal axis is at least 10° inclined from said handle longitudinal axis in an opposite direction, said hinge further comprising biasing means urging said head to be and remain in said first position, said biasing means applying a force in said first direction on said head in the range of 2 ounces to 12 ounces, and said biasing means having a threshold whereby when a force is applied to it in said second direction and of a magnitude greater than said threshold level it reverses its force to said second direction and thereby moves said head to said second position .

24. A toothbrush having a handle having proximal and distal ends, a head having a longitudinal axis and having bristles extending generally in a first direction transverse of said longitudinal axis, and a hinge connecting said head to said distal end of said handle, said hinge holding said head in a first normal orientation relative to said handle, said hinge releasably biasing said head to said first orientation, said head being movable relative to said handle about said hinge in a second direction opposite said first direction to a second orientation when a force of predetermined magnitude is applied to said head in a second direction.

25. A toothbrush according to claim 23 wherein said longitudinal axis in said second orientation is in the range of 10 to 30 degrees pivoted from said orientation of said longitudinal axis of said normal orientation.

26. A toothbrush according to claim 23 wherein said hinge comprises a bi-stable spring which applies said force of predetermined magnitude and thereby biases said head either toward said first orientation or toward said second orientation, and when a force greater than said predetermined magnitude is applied to said head which moves said head from one of said orientations toward said other orientation, said spring causes said head to snap to said second of said orientations .

27. A toothbrush according to claim 26 wherein said second orientation positions said head in a position wherein said head is angled at least 30 degrees relative to said handle.

28. A toothbrush according to claim 26 wherein said hinge comprises an elongated spring which is maintained in axial compression and bowed in configuration, and which spring in one of said orientations when additional compression force is applied, snaps to the other of its orientations.

29. A toothbrush according to claim 26 wherein said spring is bowed to a concave configuration in one of its orientations and moves through an S-shape when it moves to its other orientation where it has a convex configuration.

30. A toothbrush according to claim 26 where said spring has an elongated spoon shape of concave configuration and which snaps to a comparable spoon shape of convex configuration when it moves to one of its second orientations .

31. A toothbrush according to claim 23 wherein said hinge comprises a yoke at said distal end of said handle, a tongue at said proximal end of said head, a pivot axis extending through said yoke and tongue whereby said head is movable between two angular positions, and restraining means releasably restraining said tongue in at least one of said positions.

32. A toothbrush according to claim 31 wherein said restraining means alternatively restrains said tongue in either one of said angular positions .

33. A toothbrush according to claim 32 further comprising a bi-stable spring urging said tongue to be and remain in either one or the other of said positions.

34. A toothbrush comprising a handle, a head with bristles and a neck interconnecting said handle and said head in a predetermined first straight or angular relationship, said head being bendable relative to said handle about a bend axis in said neck, said neck having a predetermined stiffness wherein said neck resists bending of said head relative to said handle, said neck being bendable about said bend axis to a second angular relationship different from said first angular relationship and back again when a force is applied to said h.ead that overcomes said stiffness of said neck.

35. A toothbrush according to claim 34 wherein said force necessary to overcome said neck' s stiffness must exceed 6 ounces .

36. A toothbrush according to claim 34 wherein said neck comprises a bi-stable spring having two stable positions corresponding respectively to said first and said second angular relationships, and said spring biases said head to be in one or the other of said angular relationships.