Patent Description:
<CIT> discloses a prior art power toothbrush.

It has been shown that exerting too much force during brushing may damage a user's tooth enamel or gums. For this reason, some electrical toothbrushes are provided with a brushing force or pressure sensor to indicate to user's when the user is brushing too hard. Some force sensors indirectly measure force by measuring a deflection in one or more components of the toothbrush. However, the toothbrush should also be able to withstand being dropped (e.g., from a height of one to two meters onto a countertop or floor) and some of the components of the toothbrush, including the force sensor may be susceptible to damage in response to large forces.

Accordingly, there is a continued need in the art for a toothbrush assembly that both permits brushing force to be determined and protects internal parts from undesirably high forces in case of unplanned impacts.

The invention is defined by the independent claim.

The present disclosure is directed to inventive apparatuses for electric toothbrushes. According to the embodiments herein, an electric toothbrush includes a mounting bracket that is compliant in response to torque in a first direction with respect to drop loads applied to the toothbrush, and relatively stiff in response to torque in a second direction with respect to brushing loads applied by the user. The toothbrush can be arranged such that the first and second directions are opposite to each other. The bracket includes a first leg and a second leg that may be optionally arranged generally in an L-shape. The bracket includes one or more arms that extend transversely from the first leg to the second leg for providing dual-stiffness functionality. The arm may include a hook that is engageable with a boss on the second leg for preventing relative rotation of the first and second legs in response to brushing loads, while permitting relative rotation of the first and second legs in response to drop loads. Alternatively, the arm may be configured to buckle in response to torque applied due to the drop loads, such as by including an outward bowing, bulge, or bending in the arm.

Generally, in one aspect, an electric toothbrush is provided. The electric toothbrush includes a handle portion having a shaft configured to receive a brushing load from a bristled end of a brush head; a sensor assembly configured to determine a deflection proportional to the brushing load with respect to a first direction associated with the brushing load, the sensor assembly including an air gap and configured to determine the deflection based on changes in the air gap; and a mounting bracket connecting between opposite sides of the air gap, the mounting bracket configured with a first bending stiffness with respect to the first direction, and a second bending stiffness with respect to a second direction substantially opposite to the first direction, wherein the first bending stiffness is greater than the second bending stiffness.

In one embodiment, the sensor assembly includes a magnet and magnetic laminations on opposite sides of the air gap configured to create a magnetic field, wherein the brushing load is determinable based on changes in the magnetic field.

In one embodiment, the electric toothbrush further includes a back-iron component adjacent to the magnet configured to conduct the magnetic field. In one embodiment, the back-iron component is arranged as a flat plate or as an L-shaped component with a weakened bend.

The electric toothbrush further includes a compliant element configured to control an amount of the deflection in response to the brushing load. In one embodiment, the compliant element includes a V-spring. In one embodiment, the mounting bracket is configured to attenuate forces applied to the mounting bracket in the second direction to protect a connection of the mounting bracket to the compliant element.

The mounting bracket includes a first leg coupled to the shaft and a second leg coupled to the compliant element. The mounting bracket includes one or more arms extending transversely between the first and second legs and may optionally include a stop configured to prevent relative movement of the first and second legs in the first direction.

In one embodiment, the stop includes a hook formed on the one or more arms that is engageable with a boss extending from the mounting bracket.

In one embodiment, the one or more arms are configured to buckle in response to force applied to the first leg in the second direction. In one embodiment, the one or more arms are bowed outwardly to promote buckling.

It should also be appreciated that terminology explicitly employed herein that also may appear in any disclosure incorporated by reference should be accorded a meaning most consistent with the particular concepts disclosed herein.

The present disclosure describes various embodiments of electric toothbrushes. More generally, Applicant has recognized and appreciated that it would be beneficial to provide an electric toothbrush that includes a dual-stiffness bracket for providing a first stiffness in response to loads applied due to user brushing that is higher relative to a second stiffness provided in response to loads applied due to dropping the toothbrush. A particular goal of utilization of certain embodiments of the present disclosure is to protect internal components of an electric toothbrush during dropping while permitting a user's brushing force to be determined.

In view of the foregoing, various embodiments and implementations are directed to an electric toothbrush that includes a mounting bracket that is compliant in response to torque in a first direction with respect to drop loads applied to the toothbrush, and relatively stiff in response to torque in a second direction with respect to brushing loads applied by the user. The toothbrush can be arranged such that the first and second directions are opposite to each other. The bracket includes a first leg and a second leg optionally arranged generally in an L-shape. The bracket includes one or more arms that extend transversely from the first leg to the second leg for providing dual-stiffness functionality. The arm may include a hook that is engageable with a boss on the second leg for preventing relative rotation of the first and second legs in response to brushing loads, while permitting relative rotation of the first and second legs in response to drop loads. Alternatively, the arm may be configured to buckle in response to torque applied due to the drop loads, such as by including an outward bowing, bulge, or bending in the arm.

Referring to <FIG>, in one embodiment, an electric toothbrush <NUM> is provided with a brush head <NUM> attached to a handle portion <NUM> (external housing for the handle portion <NUM> removed from this view to facilitate discussion of the components of the handle portion <NUM>). The brush head <NUM> includes a neck <NUM> extending from the handle portion <NUM> and a bristled end <NUM> distal from the handle portion <NUM>, e.g., for engaging against and brushing a user's teeth while the toothbrush <NUM> is in use. For example, the handle portion <NUM> may include a drive assembly <NUM> configured to cause vibrations, oscillations, or other movement of the brush head <NUM> to assist in brushing the user's teeth with the bristled end <NUM>.

During typical use, the brush head <NUM>, due to the user forcibly engaging the bristles of the end <NUM> against the surface of the user's teeth, will result in a brushing force or load <NUM> against the brush head as indicated by an arrow in <FIG>. As discussed in more detail below, the brushing load <NUM> may result in torque applied to components of the toothbrush <NUM> in a direction <NUM> shown in <FIG>. That is, the neck <NUM> essentially acts as a lever arm for applying a torque in the direction <NUM> as a result of the brushing load <NUM>. The toothbrush <NUM> includes a sensor assembly <NUM> to measure a displacement or deflection between selected components of the toothbrush <NUM>, from which the brushing load <NUM> can be determined. The components of the sensor assembly <NUM> can be better appreciated from the enlarged view of <FIG> (with additional housing support structures removed for clarity), the cross-sectional view of <FIG>, and the perspective view of <FIG>, which are discussed in more detail below.

In order to determine the brushing load <NUM> from the deflection of selected components of the toothbrush <NUM>, the sensor assembly <NUM> includes or is used in combination with a compliant element with a known compliance profile or constant (e.g., deflecting in known amounts in response to applied loads). In this way, the amount of deflection can be reliably converted into a value for the brushing load <NUM> based on the known compliance properties of the compliant element. As discussed in more detail below, a high stiffness in the force path that includes the compliant element can be useful to enable the deflection of the compliant element to accurately quantify the brushing load <NUM>, while protecting other components of the toothbrush <NUM>.

However, as discussed in more detail below, a high level of stiffness may hinder the ability of the toothbrush <NUM> to withstand applied forces in other directions, such as, for example, those resulting from the toothbrush <NUM> being dropped. Arrows are providing in <FIG> to represent the directions of drop loads <NUM>, e.g., which may result from the toothbrush being dropped from a hand held position onto a sink, countertop, or floor. The drop loads <NUM> result in torque applied to components of the toothbrush <NUM> in a direction <NUM> (as shown in <FIG>) generally opposite to the direction <NUM> for the brushing load <NUM>. The embodiments disclosed herein advantageously attenuate the drop loads <NUM> to protect vulnerable internal components of the toothbrush <NUM> from torque in the direction <NUM> while permitting some degree of deflection in the direction <NUM> due to the brushing load <NUM> to be measured, thereby enabling the value of the brushing load <NUM> to be determined using the sensor assembly <NUM> while still providing drop protection for the internal components of the toothbrush.

Displacement, from which the value of the brushing load <NUM> can be determined, may be measured between opposite sides of an air gap <NUM>, shown best in <FIG>. That is, in this embodiment, the brushing load <NUM> results in a widening of the air gap <NUM> due to deflections of the toothbrush <NUM>, while either of the drop loads <NUM> results in a narrowing of the air gap <NUM> due to deflections in the direction <NUM>. In one embodiment, the width of the air gap <NUM> may be measured to determine the brushing load <NUM>. Additionally or alternatively, the widening of the air gap <NUM> may be accompanied by a misalignment of the components on opposite side of the air gap <NUM> in the same direction as the brushing load <NUM>, which can be measured.

As shown in <FIG>, the sensor assembly <NUM> includes a magnet <NUM> and laminations <NUM> positioned on opposite sides of the air gap <NUM>, and which together produce a magnetic field. Accordingly, displacement of the components on opposite sides of the air gap <NUM> may be determined from changes in the magnetic field (e.g., from measured changes in current and/or voltage resulting from changes in the magnetic field). In one embodiment, a Hall Effect sensor, positioned on the same side of the air gap <NUM> as the laminations <NUM>, may be used to determine the displacement based on changes in the magnetic field measured by the sensor as the sensor is moved relative to the magnet <NUM> while the air gap <NUM> widens and narrows due to the applied forces. In another embodiment, displacement may be measured by use of a proximity sensor (e.g., infrared, ultrasonic, etc.) mounted on one side of the air gap <NUM> that senses the distance to a surface on the opposite side of the air gap <NUM>. For example, an optical sensor may be included to measure the distance from one side of the air gap <NUM> (e.g., the optical sensor mounted to the side with the laminations <NUM>) to a surface on the other side of the air gap <NUM> (e.g., the surface of the magnet <NUM> or other component facing the air gap <NUM>). Additionally, similar to that noted above, instead of measuring the width of the air gap <NUM>, any such sensor may measure deflections of components on opposite sides of the air gap <NUM> in a direction transverse (e.g., substantially perpendicular) to the longitude of the toothbrush <NUM>. For example, an optical sensor could be arranged to measure the displacement of the components with respect to the same direction that the brushing load <NUM> is being applied (e.g., in a "downward" direction with respect to the orientation of <FIG>). Those of ordinary skill in the art will recognize other manners for measuring the displacement on opposite sides of an air gap.

As noted above, the toothbrush <NUM> includes a compliant element that defines a relationship between displacement of the air gap <NUM> and the value of the applied brushing load <NUM>. For example, a spring or other resilient element with a quantifiable compliance, such as the V-spring <NUM> in the embodiment of <FIG>, can be utilized. That is, the V-spring <NUM> can be selected that deflects a set or known amount in response to different values for the brushing load <NUM>. In this way, the displacement measured by the sensor assembly <NUM> can be reliably converted into a value for the brushing load <NUM> based on the known compliance of the V-spring <NUM>. It can be appreciated that other types of elements with quantifiable compliance other than a V-spring can also be used.

Referring particularly to <FIG>, the inclusion of a seal <NUM> around the shaft <NUM> may be used prevent toothpaste, saliva, water, etc. from entering the handle portion <NUM> if there is displacement of the shaft <NUM>, such as during operation, thereby causing corrosion, degradation, and/or damage of internal components, particularly steel components and electronics.

A mounting bracket <NUM> may be included that connects the components on opposite sides of the air gap <NUM> together. More particularly, the bracket <NUM> in the illustrated embodiment is a substantially L-shaped component that connects to both the shaft <NUM> and the V-spring <NUM>. The mounting bracket <NUM> can be included to increase the stiffness of the force path to the V-spring <NUM>, thereby limiting the degree of deflection. A back-iron component <NUM> for the magnet <NUM> (e.g., conducting the static magnetic field from the magnet <NUM>) may additionally and/or alternatively be included. Additionally, the back-iron component <NUM> may optionally include one or more stiffeners <NUM> to further increase stiffness for preventing deflection.

To protect the handle portion <NUM> and components therein from the drop impacts <NUM>, it may be beneficial to provide some degree of compliance or flexibility in the mounting bracket <NUM>. For example, a lower stiffness will enable the mounting bracket <NUM> to more readily move, e.g., to narrow or close the air gap <NUM>, without overloading the connection between the mounting bracket <NUM> and the V-spring <NUM>. For example, the mounting bracket <NUM> and the V-spring <NUM> may be welded together. This, in view of the above and in accordance with the embodiments disclosed herein, it is desirous for the brushing load <NUM> to be fully communicated through the mounting bracket <NUM> to the V-spring <NUM> via a high stiffness in the mounting bracket <NUM>, while a relatively lower stiffness for the mounting bracket <NUM> is desired with respect to the drop loads <NUM> in order to protect welds or other affixation mechanism to the V-spring <NUM>.

Accordingly, the relevant portion of the toothbrush is illustrated in <FIG> having a dual-stiffness mounting bracket <NUM> in place of the mounting bracket <NUM> above. Similar to the mounting bracket <NUM>, the dual-stiffness mounting bracket <NUM> is a substantially L-shaped component having a first leg <NUM> (connected to the shaft <NUM>) and a second leg <NUM> (connected to the V-spring <NUM>). It is to be appreciated that due to the brushing load <NUM>, the first leg <NUM> and the second leg <NUM> will be biased toward each other in the first direction <NUM>, while the drop loads <NUM> will cause the legs <NUM> and <NUM> to be biased away from each other in the direction <NUM>. Relative rotation of the legs <NUM> and <NUM> may occur at a junction or bend <NUM> from which the legs <NUM> and <NUM> extend from each other. For example, the junction <NUM> may act akin to a hinge that permits the legs <NUM> and <NUM> to resiliently flex with respect to each other about an axis of rotation <NUM>, i.e., thereby changing the angle between the legs <NUM> and <NUM>.

By dual-stiffness it is meant that the mounting bracket <NUM> has a first stiffness (or resistance to bending) with respect to the brushing load <NUM> and deflections in the first direction <NUM>, and second stiffness (or resistance to bending) for the drop loads <NUM> and deflections in the second direction <NUM>. The mounting bracket <NUM> can be configured so that the first stiffness (with respect to the first direction <NUM>) is greater than the second stiffness (with respect to the second direction <NUM>). In other words, with respect to the second direction <NUM>, the mounting bracket <NUM> absorbs at least some of the force, or directs at least some of the applied force along a force path that bypasses or avoids the interface with the V-spring <NUM>, in order to attenuate the forces applied to welds or other connection between the V-spring <NUM> and the mounting bracket <NUM> due to the drop loads <NUM>. The dual-stiffness functionality of the mounting bracket <NUM> is accomplished by one or more arms <NUM>, e.g., arranged on opposite sides, that extend transversely from the first leg <NUM> toward the second leg <NUM>.

Each of the arms <NUM> is only affixed to the first leg <NUM> (e.g., integrally formed), and thus can move with the first leg <NUM> relative to the second leg <NUM>. However, the mounting bracket <NUM> has a stop <NUM> that prevents or limits relative deflection of the legs <NUM> and <NUM> in the direction <NUM> of the brushing load <NUM>. In this way, the stiffness provided by the mounting bracket <NUM> is greater with respect to the first direction <NUM> for the brushing load <NUM> than the second direction for the drop loads <NUM>. In <FIG>, the stop <NUM> is formed by a hook <NUM> in the arm <NUM> that is configured to engage with (grab) a boss <NUM> extending from the second leg <NUM>. To prevent rattling noise from the hook and boss during operation of the toothbrush <NUM>, the arms <NUM> can be mounted under some pre-tension using the natural stiffness of the material forming the frame bracket <NUM>. Those of ordinary skill in the art will recognize other one-way latch mechanisms that can be utilized in lieu of the hook <NUM> and the boss <NUM>.

A mounting bracket <NUM>' according to another embodiment is illustrated in <FIG>, with the mounting bracket <NUM>' shown installed in the relevant portion of the toothbrush <NUM> in <FIG>. Similar to the mounting bracket <NUM>, the mounting bracket <NUM>' has one or more arms <NUM>' (two shown in <FIG>) that transversely extend from the first leg <NUM> to the second leg <NUM>. However, unlike the arms <NUM>, the arms <NUM>' are affixed to both the leg <NUM> and the leg <NUM>. For example, the arms <NUM>' may be integrally formed with the leg <NUM> and attached to the leg <NUM> via welds <NUM> or some other manner of affixation, such as adhesive, bolts, etc. To provide relative decreased stiffness for the drop loads <NUM>, the arms <NUM>' are configured to buckle in the direction <NUM>. To promote buckling, the arms <NUM>' may be outwardly bent, bulged, bowed, or arched. To better appreciate the curvature in the arms <NUM>', a dashed line <NUM> is shown in <FIG> that indicates where the top edge of the inner surface of the arm <NUM>' would have been if the arm were not bent. Those of ordinary skill in the art will recognize other ways in which arms may be configured to more readily buckle in one direction. For example, the arms may be replaced in one embodiment with wires connected between the legs <NUM> and <NUM> that offer little or no resistance to bending in the direction <NUM> due to the drop loads <NUM>, but which offer high tensile resistance in the opposite direction <NUM> to the brushing load <NUM>.

It is also noted that contribution to the bending stiffness may be provided by the back-iron component <NUM> for the magnet <NUM>. In embodiment of <FIG>, a back-iron component <NUM> is included that is formed as a generally L-shaped bracket that is weakened at a bend <NUM>, e.g., by including substantially less cross-sectional thickness at the bend <NUM>. In this way, the bend <NUM> may operate akin to a living hinge, thereby reducing stiffness and promoting flexibility in the back-iron component <NUM>.

In one embodiment, shown in <FIG>, a back-iron component <NUM> is included and formed as a single plate instead of an L-shaped bracket. In this way, the bending stiffness in the handle portion <NUM> is provided by the bracket <NUM> without contribution by the back-iron component <NUM>. An additional advantage to omitting the bottom part or base of the back-iron component <NUM> is that the inertia contribution of the back-iron component is decreased relative to L-shaped embodiments, thereby permitting increased freedom for designing or adding other components, without overly increasing the high for this portion of the assembly.

While several inventive embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the inventive teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims, inventive embodiments may be practiced otherwise than as specifically described and claimed. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material and/or kit, described herein. In addition, any combination of two or more such features, systems, articles, materials and/or kits, if such features, systems, articles, materials,and/or kits, are not mutually inconsistent, is included within the inventive scope of the present disclosure.

Claim 1:
An electric toothbrush (<NUM>) comprising:
a handle portion (<NUM>) having a shaft (<NUM>) configured to receive a brushing load (<NUM>) from a bristled end (<NUM>) of a brush head (<NUM>);
a sensor assembly (<NUM>) configured to determine a deflection proportional to the brushing load with respect to a first direction (<NUM>) associated with the brushing load, the sensor assembly including an air gap (<NUM>) and configured to determine the deflection based on changes in the air gap; and
a compliant element (<NUM>) configured to control an amount of the deflection in response to the brushing load,
characterized in that the toothbrush further comprises
a dual-stiffness mounting bracket (<NUM>) connecting between opposite sides of the air gap, the mounting bracket including a first leg (<NUM>) coupled to the shaft and a second leg (<NUM>) coupled to the compliant element; wherein the mounting bracket includes one or more arms (<NUM>, <NUM>') extending transversely between the first leg and the second leg and configured to prevent relative rotation of the first and second legs in the first direction in response to brushing loads, while permitting relative rotation of the first and second legs in a second direction (<NUM>) substantially opposite to the first direction in response to drop loads, such that the mounting bracket is configured with a first bending stiffness with respect to the first direction, and a second bending stiffness with respect to the second direction , wherein the first bending stiffness is greater than the second bending stiffness.