System for determining brushing parameters for an electric toothbrush

Abstract

The brush head (12), electric toothbrush (10), and method of operating an electric toothbrush are disclosed. The electric toothbrush (10) includes bristles extending from a base structure. A plurality of tufts (20) are formed as distinct groups of bristles (23) that are bundled together. A sensor assembly (28) is configured to generate, for each of the tufts, a signal representative of the force applied to each of the tufts. A controller (18) is configured to generate a tuft signature representative of the distribution of the force applied to each of the tufts. The tuft signature is then classified by a suitable algorithm to determine brushing parameters, such as location in a user's mouth, angle, and applied force.

Description

[Technical Field]

[0001] The present disclosure is directed generally to electric toothbrushes, and more particularly to systems and methods for determining brushing parameters when using an electric toothbrush. [Background technology]

[0002] Brushing technique and compliance are key indicators of oral health. Dental professionals provide guidance but typically rely on self-reporting to assess patients' brushing technique. Similarly, individuals attempt to brush well but often do not receive feedback until their biannual checkup. During each brushing session, the user must apply the appropriate amount of pressure at the correct angle to cover all tooth surfaces for adequate plaque removal without damaging the user's teeth or gums.

[0003] One challenge with current toothbrushes is resolving the location of the end effector (bristles) within the mouth. For example, inertial motion units (e.g., accelerometers, gyroscopes, magnetometers) are subject to drift due to errors in double integration from acceleration to position. Also, a toothbrush user's upper and lower jaws may be in close proximity, making it difficult to distinguish between them. Furthermore, pressure-sensitive toothbrushes can help identify whether a user is brushing too vigorously, but they rely on the overall applied force measured at the handle. As a result, pressure may not be accurately determined in some situations, such as for a user who presses the toothbrush head against their teeth with their cheek. Additionally, determining the angle of the toothbrush relative to the user's teeth is another challenge because users typically move their head relative to the toothbrush while brushing, so the orientation of the user's teeth is unknown to the toothbrush. As a result, users may be required to follow a set routine or brush in front of a camera to most accurately track the location of the bristled end of the toothbrush within the user's mouth. Summary of the Invention [Problem to be solved by the invention]

[0004] Thus, there continues to be a need in the art for more accurate monitoring of brushing parameters such as the pressure applied to a user's teeth and the location, angle, and / or orientation of the bristle ends of a toothbrush relative to the user's teeth.

[0005] US Patent No. 5,949,663 discloses a brush having tufts of bristles, each tuft slidably secured within a hole. When a force greater than a critical value is applied to the brush, a microswitch is activated, warning the user about applying excessive force.

[0006] US Patent No. 5,949,999 discloses a visible light-emitting toothbrush that can emit light when the toothbrush is placed in a user's mouth, but stops when removed.

[0007] US Patent No. 5,949,999 discloses an oral cleaning device comprising bristle tufts connected to a sensor, the sensor being able to sense the pressure exerted by the tufts.

[0008] US Patent No. 5,949,693 discloses a toothbrush with a three-point force sensing system. [Means for solving the problem]

[0009] The present disclosure is directed to an inventive electric toothbrush, and more particularly to a system and method for determining brushing parameters such as pressure, angle, and location of a brush head of an electric toothbrush during brushing. A toothbrush is composed of many individual tufts of bristles. The geometry of each tooth varies from place to place and person to person. The geometry of each individual tuft (e.g., size, shape, length, material, stiffness, etc.) targets a specific function and / or location in the user's mouth. At any given location in the mouth, only a subset of the total number of tufts, e.g., 10-25%, are designed or expected to bear a disproportionate portion of the total pressure applied by the user. As a result, the distribution of applied pressure across the array of tufts changes during use. For a particular toothbrush user, the pattern of tufts that concentrate pressure may be unique or specific to a given location in the mouth, brush head angle, and applied load.

[0010] An embodiment is disclosed for an electric toothbrush that can monitor force on individual tufts. The force distribution across the individual tufts can be used to develop distinct tuft signatures indicative of brushing parameters, such as the location, angle, and / or pressure of the bristle ends of the toothbrush during brushing. In one embodiment, the tufts are configured as part of a sensor assembly to each create a normally open switch that requires a predetermined axial force to close. The tuft signatures generated from the collected sensor data can be analyzed by an algorithm and / or fused with data from other sensors to enhance the feedback that can be provided during brushing. For example, the location of the brush head in the user's mouth, the angle of the brush head, and the determination of applied pressure can all be improved.

[0011] Generally, in one aspect, a brush head for an electric toothbrush includes bristles extending from a base structure, an array of tufts, each tuft formed as a separate group of bristles bundled together, and a sensor assembly configured to generate, for each of the tufts, a signal representative of a force applied to each of the tufts.

[0012] In one embodiment, each of the tufts is movable relative to the base structure in response to a force, and the sensor assembly is configured to selectively form an electrical connection that generates a signal when the force exceeds a threshold value.

[0013] In one embodiment, the base structure includes a rigid platen to which the conductive elements are attached and a flexible layer in which the tufts are embedded, the elasticity of the flexible layer allowing the tufts to move relative to the base structure, hi one embodiment, each of the tufts includes a conductive surface that is displaced into contact with the conductive elements when a threshold force is exceeded.

[0014] In one embodiment, the brush head further includes a conductive layer for one or more of the tufts that is pushed by a corresponding one of the tufts to contact the conductive element when a force exceeds a threshold. In one embodiment, the conductive element is a discontinuous element, and the electrical connection electrically connects the discontinuous elements. In one embodiment, the discontinuous element includes two planar halves or two raised pads.

[0015] In general, in another aspect, an electric toothbrush includes a brush head according to claim 1 and a controller configured to generate a tuft signature representative of a distribution of applied force across an array of tufts.

[0016] In one embodiment, the controller is configured to classify the angle of the brush head relative to the user's teeth depending on the tuft signature.In one embodiment, the controller is configured to classify the pressure exerted by the brush head against the user's teeth depending on the tuft signature.

[0017] In one embodiment, the tuft signatures include a plurality of training tuft signatures and a current tuft signature, the controller is configured to create a signature map during the training process that associates each of the training tuft signatures with a particular location in the user's mouth, and the controller is configured, during use, to determine the location of the brush head in the user's mouth by comparing the current tuft signature with the signature map.

[0018] In one embodiment, the controller is configured to receive position data from the position sensor and fuse the position data with the tuft signatures to recalibrate or verify the determined position of the brush head within the user's mouth.

[0019] Generally, in one embodiment, a method of operating an electric toothbrush includes receiving a force for each of a plurality of tufts of a brush head of the electric toothbrush, generating, for each of the tufts, a signal representative of the force applied to each of the tufts individually, and generating a tuft signature representative of the distribution of the forces applied to the tufts.

[0020] In one embodiment, the tufts are configured as normally open switches movable relative to a base structure of the brush head in response to a force, and generating includes forming an electrical connection with a given one of the tufts to generate a signal when the force exceeds a threshold value for that given one of the tufts.

[0021] In one embodiment, the method further comprises determining at least one of a position of the brush head in the user's mouth, an angle of the brush head relative to the user's teeth, and a brushing force applied by the user from the tuft signature.

[0022] It should be understood that all combinations of the foregoing concepts, and additional concepts discussed in more detail below, are contemplated as being part of the inventive subject matter disclosed herein (unless such concepts are mutually inconsistent). In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein. Terminology explicitly utilized herein, which may appear in any disclosure incorporated by reference, should be given the meaning most consistent with the particular concepts disclosed herein.

[0023] In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. [Brief explanation of the drawings]

[0024] [Figure 1] 1 illustrates a schematic diagram of an electric toothbrush according to one embodiment disclosed herein.

[0025] [Figure 2] 1 illustrates a brush head having multiple bristle tufts according to one embodiment disclosed herein.

[0026] [Figure 3A] 1 illustrates example bristle tufts for a brush head of a toothbrush according to embodiments disclosed herein. [Figure 3B] 1 illustrates example bristle tufts for a brush head of a toothbrush according to embodiments disclosed herein.

[0027] [Figure 4] FIG. 1 is a cross-sectional view of a tuft in the base of a brush head forming a sensor assembly according to one embodiment disclosed herein.

[0028] [Figure 5] FIG. 10 is a cross-sectional view of tufts in the base of a brush head illustrating how the tufts may be arranged to form a normally open switch that can be transitioned to a closed state according to one embodiment disclosed herein.

[0029] [Figure 6] FIG. 10 is a cross-sectional view of a tuft installed within the base of a brush head of a toothbrush according to another embodiment disclosed herein.

[0030] [Figure 7] 1A-1C are side cross-sectional and top views illustrating components of a sensor assembly according to one embodiment of the present disclosure.

[0031] [Figure 8] 1A-1C are side cross-sectional and top views illustrating components of a sensor assembly according to one embodiment of the present disclosure.

[0032] [Figure 9]1 is a block diagram describing a method and system for operating an electric toothbrush to determine brush head pressure and / or angle according to one embodiment disclosed herein.

[0033] [Figure 10A] 1 illustrates various exemplary bristle signatures that may represent or be associated with different angles and / or pressures of the bristle ends of a brush head during brushing. [Figure 10B] 1 illustrates various exemplary bristle signatures that may represent or be associated with different angles and / or pressures of the bristle ends of a brush head during brushing. [Figure 10C] 1 illustrates various exemplary bristle signatures that may represent or be associated with different angles and / or pressures of the bristle ends of a brush head during brushing. [Figure 10D] 1 illustrates various exemplary bristle signatures that may represent or be associated with different angles and / or pressures of the bristle ends of a brush head during brushing. [Figure 10E] 1 illustrates various exemplary bristle signatures that may represent or be associated with different angles and / or pressures of the bristle ends of a brush head during brushing.

[0034] [Figure 11] 1 illustrates various exemplary tuft signatures that may represent or be associated with different locations of the bristle ends of a brush head within a user's mouth during brushing.

[0035] [Figure 12] FIG. 1 is a block diagram describing a method and system for operating an electric toothbrush to determine the location of a brush head according to one embodiment disclosed herein. DETAILED DESCRIPTION OF THE INVENTION

[0036] The present disclosure describes various embodiments of an electric toothbrush. Applicant has recognized and appreciated that it would be beneficial to provide an electric toothbrush configured with a sensor assembly that monitors the force applied to each individual tuft of bristles in the brush head of the toothbrush. A particular goal of utilizing certain embodiments of the present disclosure is to more accurately determine brushing parameters, such as the pressure, angle, and location of the brush head of the electric toothbrush during brushing.

[0037] In view of the foregoing, various embodiments and implementations are directed to electric toothbrushes, and more particularly, to systems and methods for determining brushing parameters, such as pressure, angle, and location of a brush head of an electric toothbrush during brushing. A toothbrush is composed of numerous individual tufts of bristles. The geometry of each tooth may vary from location to location and person to person. The geometry of each individual tuft (e.g., size, shape, length, material, stiffness, etc.) targets a specific function and / or location within the user's mouth. At any given location within the mouth, only a subset of the total number of tufts, e.g., 10-25%, are designed or expected to bear a disproportionate portion of the total pressure exerted by the user. As a result, the distribution of applied pressure across the array of tufts varies during use. For a particular toothbrush user, the pattern of tufts concentrating pressure may be unique or specific to a given location within the mouth, brush head angle, and applied load.

[0038] An embodiment of an electric toothbrush is disclosed that can monitor force on individual tufts. The force distribution across the individual tufts can be used to develop distinct tuft signatures that indicate the location, angle, and / or pressure of the bristled end of the toothbrush during brushing. In one embodiment, the tufts are configured as part of a sensor assembly to create normally open switches that each require a predetermined axial force to close. The tuft signatures generated from collected sensor data can be analyzed by an algorithm and / or fused with data from other sensors to enhance the feedback that can be provided during brushing. For example, the location of the brush head in the user's mouth, the angle of the brush head, and the determination of applied pressure can all be improved.

[0039] Referring to FIG. 1 , an electric toothbrush 10 according to one embodiment is illustrated having a brush head 12 and a handle assembly 14. The brush head 12 includes bristle ends 16 distal from the handle assembly 14, for example, to engage and brush a user's teeth while the toothbrush 10 is in use. For example, the handle assembly 14 may include a drive assembly (e.g., a motor) configured to cause vibration, reciprocation, or other movement of the brush head to assist the bristle ends 16 in brushing the user's teeth. The brush head 12 may be a separate component removably attachable to the handle assembly 14, for example, to enable different functions for the toothbrush 10 or to allow the user to replace the brush head periodically (e.g., every three months) as soon as the bristle ends 16 become overused or worn.

[0040] The toothbrush 10 may include a controller 18 configured to control the operation of the toothbrush 10. For example, the controller 18 may include corresponding hardware (e.g., a processor, memory, a communications module, a position sensor, etc.) and software (e.g., an application, firmware, etc.) configured to enable one or more different operational modes for the toothbrush 10. The controller 18, in whole or in part, may be included in or embedded in the handle assembly 14 and / or the brush head 12. The controller 18 may enable data communication with one or more external or remote devices, such as a smartphone or a cloud-based server. For example, a software application on the smartphone may be associated with the toothbrush 10 to enable a user to interface with the toothbrush 10 via a graphical user interface, etc., and configured to receive and display data collected by sensors in the toothbrush 10. It should be understood that the controller 18 may be at least partially formed by or otherwise utilize external computing resources of this type to assist in providing its functionality as described herein. The use of controller 18 in storing and analyzing data collected from one or more sensors embedded in brush head 12 is discussed in more detail below.

[0041] The bristle end 16 of the toothbrush 10 includes a large number of individual filaments or bristles grouped into a plurality of tufts 20 extending from the base 22 of the brush head 12. For example, the brush head 12 includes 20 tufts 20 in the embodiment of FIG. 2 (each of the tufts 20 is shown schematically as a dot). It should be understood that any number of tufts 20 may be included, and any number of individual bristles may be included in each tuft 20. Each of the tufts 20 may have a uniform size and shape (e.g., each may have the same number of bristles arranged in the same shape or pattern), or various ones of the tufts 20 may include a greater or lesser number of bristles grouped in the same or different shapes, and / or the bristles may have different lengths, materials, thicknesses, or configurations.

[0042] In one embodiment, tufts 20 are formed by securing one end of the bristles together, for example, by melting, clamping, crimping, gluing, or fastening. For example, as shown in FIG. 3A, tuft 20A is formed by a ring 24 secured around a group of bristles 23 that maintains tuft 20A as a separate or individual unit. In FIG. 3B, tuft 20B includes a slug of material 25 created by fusing (e.g., melting, welding, etc.) the group of bristles 23 together. It should be understood that tufts 20A and 20B are specific examples of tufts 20, and that any description of tuft 20 generally applies to both tufts 20A and 20B. As discussed in more detail below, a surface of tuft 20 opposite the free ends of the bristles (e.g., a back or bottom surface) is provided as a conductive surface 26. The ring 24, slug of material 25, etc. may help maintain the tuft 20, including the conductive surface 26, in a desired shape, e.g., the circular shape of Figure 3A, the diamond shape of Figure 3B, etc., although any other shape may be utilized. As with a conventional toothbrush, the bristles opposite the ring 24 and / or slug of material 25 may be free or unattached to facilitate brushing.

[0043] 4 shows a cross-sectional view of one of the tufts 20 embedded or potted within the base 22 of the brush head 12 to form a sensor assembly 28. In this embodiment, the base 22 includes a flexible layer 30 (e.g., an elastic or resiliently deformable plastic) secured to a rigid platen 32 (e.g., a hard plastic). The sensor assembly 28 includes a conductive element 34 on the platen 32 opposite the conductive surface 26 of each tuft 20. The resilience of the material forming the flexible layer 30 can be used to maintain an air gap 36 between the conductive surface 26 and the conductive element 34.

[0044] The conductive surface 26 and conductive elements 34 may be formed by coating or cladding the tufts 20 and platen 32 with metal, or by otherwise metallizing or providing metal elements for the respective components. For example, metallization of the platen 32 may be achieved by patterning an existing polymer platen via a contact mask (i.e., physical structures on the surface that guide metal deposition) or a photomask (i.e., a photosensitive polymer patterned via exposure to ultraviolet light). The tufts 20 may be metallized in a variety of different ways. For example, individual tufts may be metallized prior to positioning relative to the injection-modeled flexible layer 30 and platen 32 to hold the tufts 20 in place. In one embodiment, the tufts are first embedded in the flexible polymer that forms layer 30, and then metal is deposited over the bottom surface of the tufts 20. This assembly is then aligned and bonded to the platen 32. Discrete contacts may be maintained by a gradation between the bottom of layer 30 or the top of platen 32 and the start of tufts 20 (defining gaps 36). In one embodiment, flexible layer 30 is pre-formed with the addition of a metal layer or metal foil. When tufts 20 are inserted, the metal layer tears around the tufts 20, achieving segmented pads.

[0045] The voids 36 may be established in a number of different ways. For example, the voids 36 may be predefined before bonding the flexible part forming the flexible layer 30 to the platen 32. In one embodiment, the voids 36 are formed by an additional layer of material between the flexible layer 30 and the platen 32 that is dissolved or otherwise removed. In one embodiment, the voids 36 are established by adding air to the part mold in corresponding locations. In one embodiment, the voids 36 are maintained by the hydrophobic surface tension behavior of a selected polymer material (e.g., for the flexible layer 30) relative to a selected metallic material (e.g., for the conductive elements 34), which forms air bubbles or pockets around each conductive component.

[0046] 5, the flexible layer 30 may allow each tuft 20 to be displaced in response to an applied force 38 (e.g., a force applied to the tufts 20 by a user engaging the bristle ends 16 of the brush head 12 against the user's teeth). If the applied force 38 is large enough (i.e., overcomes the inherent elasticity of the flexible layer 30), the conductive surface 26 may be forced into contact with the conductive elements 34, thereby establishing an electrical connection. For example, as shown, the voids 36 may have a width "x" such that application of the applied force 38 elastically deforms the flexible layer 30, shifting the tufts 20 by an amount Δx, thereby bringing the conductive surfaces 26 and the conductive elements 34 into contact with one another.

[0047] As described above, the resilience of the flexible layer 30 can be used to bias the tufts 20 away from the conductive elements 34. Consequently, each tuft 20, together with its conductive surface 26 and respective conductive element 34 within the base 22, is configured to act as a normally open switch (the term "tuft switch" may be used for ease of discussion herein). In this manner, the sensor assembly 28 may be formed as an array of tuft switches, each configured in this manner. The electrical connection between the conductive surface 26 and the conductive element 34 can be identified, for example, by the controller 18, as a change in an electrical parameter resulting from the electrical connection, such as potential (ΔV), current, resistance, capacitance, impedance, etc. For example, each tuft 20 configured as a switch can be assigned or associated with a unique address known by the controller 18. As discussed in more detail below, for example, the known locations or addresses can be used by the controller 18 to map the distribution of forces applied to the bristle ends 16 during a brushing event in the user's mouth.

[0048] In one embodiment, the material properties and dimensions of flexible layer 30 can be selected to set the value of the applied force 38 required to displace each tuft 20 by a distance x. In other words, the material properties and dimensions of tufts 20 are determined so that the applied force 38 does not exceed a threshold F for that tuft 20. close A threshold force F is applied so that each chamber switch is only transitioned to the closed configuration when close For example, such a threshold force may be set as a force that is approximately equal to or derived from a recommended brushing force or pressure (e.g., that adequately cleans the user's teeth without damaging the user's tooth enamel and / or gums). In this manner, sensor assembly 28 can determine which of tufts 20 are reaching threshold force F. close The device is configured to generate a signal for each of the tufts 20 depending on the presence or absence of an electrical signal indicative of whether the tufts 20 are subjected to an applied force 38 across the tufts 20 .

[0049] It should be understood that the force applied to each tuft 20 can be determined in a variety of ways; for example, an alternative embodiment of tuft 20C is shown in FIG. 6 in which the bottom surface of tuft 20C is not conductive (i.e., tuft 20C does not include conductive surface 26). Instead, a metallization or conductive layer 40 is provided on, within, or through flexible layer 30, and an air gap 36 is created between conductive layer 40 and conductive element 34. As another example, any or all of the conductive components may be removed and replaced with a force sensor configured to determine the applied force. For example, one or more piezoelectric elements may be included that generate a voltage in response to the applied force. In another embodiment, magnetic components may be included in tufts 20 and / or base 22, and a Hall Effect sensor is used to detect when tuft 20 is displaced by a sufficiently high force. In one embodiment, a separate biasing element, e.g., a spring, may be included instead of or in addition to flexible layer 30, allowing the threshold closure force to be more specifically set. Those skilled in the art will recognize other sensor assemblies that can be used to measure or otherwise determine force.

[0050] In one embodiment, the conductive element 34 is a discontinuous element, including two halves 42a and 42b, as shown in FIG. 7 . In this manner, when the conductive surface 26 contacts the conductive element 34, the conductive surface 26 completes an electrical connection between the halves 42a and 42b to create the aforementioned electrical signal. As shown in FIG. 8 , the conductive element 34 may include separate raised pads 44a and 44b instead of the planar structure of FIG. 7 . Those skilled in the art will recognize that these are only two examples and that other structures for the conductive element 34 are possible. For example, the conductive element 34 may be a continuous element with half of an electrical circuit connected to each of the conductive element 34 and the conductive surface 26, such that a circuit is completed when electrical contact is made between the conductive element 34 and the conductive surface 26.

[0051] Regardless of the structure of the sensor assembly 28, the controller 18 can be configured to monitor the state of each chamber 20. For example, for embodiments in which each of the chambers 20 forms, at least in part, a normally open switch, the controller 18 can be configured to monitor which of the chambers 20 is open versus which of the chambers 20 is in a closed state. That is, the controller 18 may register a "1" if the applied pressure closes the switch, and a "0" otherwise. In embodiments utilizing piezoelectric or other force sensors, the controller 18 may be configured to detect the force applied to each of the chambers.

[0052] 9 is a block diagram illustrating how the state of the tuft switches can be analyzed by the controller 18 to, for example, determine or verify the angle, pressure, and estimated location of the bristle ends 16 in the user's mouth. In step 46, the controller 18 obtains the state of each tuft 20 (e.g., "0" for an open switch, "1" for a closed switch) from the sensor assembly 28, as described above. In this step, time-domain data from all tufts may be obtained from the brush head. As described above, the sensor modality may be a number of different electrical parameters (e.g., voltage, current, resistance, impedance, capacitance). In this step, the frequency of sampling (e.g., how often the state of the tuft switches is checked) and the duration of the sample packet can be set (i.e., analyze one sampling cycle at a time or analyze "n" cycles together).

[0053] If desired, the angle of the bristle ends 16 relative to the user's teeth may be obtained or estimated in step 48. For example, the angle of the bristles relative to the user's teeth may affect the distribution of forces on the tufts 20, and therefore this input may be useful in identifying and / or distinguishing between different rotational states. The measurement may be direct (e.g., an encoder) or indirect (e.g., a motor parameter such as current draw).

[0054] The data acquired or generated in steps 46 and / or 48 may be fed to a filter module 50. For example, the raw acquired data is likely to be noisy, and therefore the signals from each of the tuft switches may be filtered. In one embodiment, only signals corresponding to applied forces above a certain minimum contact duration threshold are considered. For example, any contacts sensed for less than about 1-10 ms, or other contact durations, may be discarded. The filter module 50 may be configured with a series of filters to segment specific portions of the data corresponding to different ranges across the angle of the brush head 12 based on the data collected in step 48.

[0055] In step 52, a tuft signature for each tuft may be generated. By tuft "signature" is meant the corresponding data from the sensor assembly 28 addressed to indicate the state of each tuft 20 at any given instant or sampling cycle. For example, the specific identification of which tuft switches are "open" and "closed" at any given instant can be analyzed as a tuft signature. Note that tuft signatures vary depending on the rotation angle and applied pressure, and can be estimated or determined from filtered data. For example, FIGS. 10A-10E show a variety of different tuft signatures based on the pattern of open (white dots) and closed (black dots) switches. That is, Figure 10A shows no load (all switches open), Figure 10B shows load on the "left" side only (relative to the orientation of Figure 10B), Figure 10C shows nominal load (e.g., some of the tuft switches are closed), Figure 10D shows load on the "right" side (relative to the orientation of Figure 10D), and Figure 10E shows overload (e.g., most of the switches are closed, indicating high pressure).

[0056] In one embodiment, the rotation determinations are grouped into at least three states defining a neutral position (bristles extending substantially perpendicular to the user's tooth surface), rotated "up" relative to the user's tooth surface, and rotated "down." Additional states may be included if a solution is sufficient and / or desired for each situation. The state of each tuft switch can be estimated as a function of one of the aforementioned rotation groups.

[0057] Once the signatures for the tufts are generated, they can be passed to classification module 54, as shown in FIG. 9. The tuft signatures from a given rotation group or group combination are analyzed and classified. Based on the contact pattern, the currently applied load can be classified; for example, the angle or rotation of the brush head can be determined as rotated up, rotated down, or centered. If the load is concentrated on a particular side throughout the cycle, the brush can be determined to be rotating in that direction. For example, depending on which side of the user's mouth the brush head 12 is positioned, the signatures in FIGS. 10B and 10D can be determined as either rotated "up" or rotated "down," because a load on only one side indicates that side is rotated toward the user's teeth. This determination can be used to supplement the angle data generated in step 48. The classification performed by classification module 54 may be determined using any technology, technique, method, or manner known or developed in the art, such as, but not limited to, heuristic models, decision trees, naive Bayes classifiers, support vector machines, machine learning, and / or artificial intelligence (neural networks, ensembles, etc.).

[0058] As an additional example, the applied pressure can be determined (e.g., using classification module 54 or other algorithms) based on the tuft signature in step 56. For example, low pressure, nominal pressure, and excessive pressure can be determined from FIG. 10A (all switches open), FIG. 10C (only a few switches closed), and FIG. 10E (most switches closed), respectively. If the number of closed tufts exceeds a certain threshold (e.g., between about 25-40% of the tuft switches are closed), controller 18 may determine that the applied force 38 is sufficient, while less than this may indicate that the user is not brushing hard enough, and more than this may indicate that the user is brushing too hard. Furthermore, if a given tuft or tufts remain closed throughout a full rotation range, brushing event, a predetermined length of time, etc., this may indicate excessive pressure. This is because the bristles may be pinned instead of sweeping (ie, the user is "scrubbing" instead of brushing).

[0059] In addition to more general classifications of applied pressure (e.g., as described above, "low," "nominal," and "excessive"), tuft signatures may be used to more quantitatively estimate applied pressure. That is, as described above, the design and manufacturing process can control the pressure at which a given tuft switch closes, and therefore the applied pressure can be estimated. At nominal load conditions, for a given tuft signature, the applied pressure can be calculated as a required closing force (e.g., a threshold force F) for each tuft. close ) and / or the surface area of ​​the tufts, it can be easily estimated from the sum of several tufts in the closed state. If the applied pressure cannot be estimated, for example, because an unacceptably large percentage (e.g., all) or small percentage (e.g., none) of the tufts exhibit a closed state, then "excess pressure" or "insufficient pressure" can be passed as output instead of a quantitative value.

[0060] In one embodiment, the relative location of the bristle ends 16 is also provided by the controller 18 as a fusion of data, for example, using the tuft signature and the output of a position sensor, such as an IMU, optical proximity sensor, etc., embedded in and / or included in the electric toothbrush 10. For example, the tuft signature may be used as a reference measurement to correct for compounding errors from an IMU embedded in the electric toothbrush 10. This may be accomplished either by building a signature map of the user's teeth over time (as the user normally brushes) or by initially scanning the user's teeth with the brush head. In the latter, the user may be guided (e.g., via printed instructions, an application installed on a smartphone, etc.) to press and rotate the brush head 12 against specific teeth where the motor is not operational and / or to follow a specific path or routine during one or more brushing sessions. This creates a map of the tuft signature as a function of angle and position in the mouth.

[0061] For example, Figure 11 schematically illustrates a signature map showing that different locations in a user's mouth may result in different patterns of contact (signatures) due to tooth geometry. Controller 18 can be trained to construct such a tuft signature map. In this manner, controller 18 can estimate the location of brush head 12 by correlating the current tuft signature sensed by sensor assembly 28 at any given moment with different locations in the user's mouth under typical brushing conditions.

[0062] The method for determining location can be understood in consideration of the block diagram of FIG. 12. Step 58 involves determining a tuft signature from the sensor assembly 28, as described above, for example, as shown in FIG. 11. The current tuft signature can be compared to a signature map for that person to estimate the location or possible location within the user's mouth. Step 60 involves obtaining location data, such as from an IMU or other position sensor in communication with the controller 18. Note that while similar signatures may be developed in the signature map for many different locations, confidence regarding a particular location at any given time may be increased by additionally considering the IMU data from step 60. To this end, step 62 involves fusing the data from steps 58 and 60 together, which leads to the calculation in step 64 of the current location of the bristle ends 16 of the brush head 12. For example, drift in the IMU may be compensated for by periodically recalibrating the sensor to the estimated position provided in step 58, or the position determined in step 58 can be verified using IMU data from step 60.

[0063] As an additional input for step 64, generalized information (e.g., collected in a clinical or laboratory setting by aggregating measurements of other users) can be provided in step 66 to assist in the analysis of the fused IMU and tuft signature data. The locations determined for each current cycle can be used to inform decisions about the next cycle. The output of controller 18 may include a graphical representation of the user's mouth (e.g., via a screen or display of a smartphone in communication with controller 18) showing areas where the user brushed too hard, angled improperly, missed, spent too little time, etc.

[0064] Advantageously, such recalibration allows the user to accurately gather brushing information without requiring the user to follow a preset or prescribed brushing routine or path. For example, the controller 18 can accurately identify the location of the bristle ends 16 even if the user quickly, abruptly, or rapidly transitions between different locations in the user's mouth, begins a brushing session at any desired location, moves their head or body around while brushing, etc.

[0065] While several inventive embodiments have been described and illustrated herein, those skilled in the art will readily conceive of various other means and / or structures for performing the functions and / or obtaining the results and / or one or more of the advantages described herein, and each such variation and / or modification 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 intended to be exemplary, and that the actual parameters, dimensions, materials, and / or configurations will depend on the specific application or applications for which the inventive teachings 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. Accordingly, it should be understood that the foregoing embodiments are provided by way of example only, and that, within the scope of the appended claims and their equivalents, inventive embodiments may be practiced otherwise than as specifically described and claimed. Inventive embodiments of the present disclosure are directed to each individual component, system, product, material, kit, and / or method described herein. Additionally, any combination of two or more such compositions, systems, articles of manufacture, materials, kits, and / or methods is included within the inventive scope of the present disclosure, provided that such compositions, systems, articles of manufacture, materials, kits, and / or methods are not mutually inconsistent.

[0066] The term "and / or," as used in the specification and claims, should be understood to mean "one or both" of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with "and / or" should be construed in the same manner, i.e., "one or more" of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the term "and / or," whether related or unrelated to the elements specifically identified. As used in the specification and claims, "or" should be understood to have the same meaning as "and / or" as defined above.

[0067] It should also be understood that, unless expressly indicated to the contrary, in any method claimed herein that includes more than one step or act, the order of the method steps or acts is not necessarily limited to the order in which the method steps or acts are recited. [Prior art documents] [Patent documents]

[0068] [Patent Document 1] U.S. Patent No. 6,412,137 [Patent Document 2] European Patent Application Publication No. 3076825 [Patent Document 3] US Patent Application Publication No. 2018 / 103747 [Patent Document 4] U.S. Patent No. 6,425,295

Claims

1. 1. A brush head for an electric toothbrush, comprising: bristles extending from the base structure; an array of tufts, each tuft being formed as a separate group of said bristles bundled together; a sensor assembly configured to generate, for each of the tufts, a signal representative of a force applied to each of the tufts; the base structure includes a flexible layer in which the tufts are embedded; the signal is caused by deformation of the flexible layer; Brush head.

2. 2. The brush head of claim 1, wherein each of the tufts is movable relative to the base structure in response to the force, and the sensor assembly is configured to selectively form an electrical connection that generates the signal when the force exceeds a threshold value.

3. The brush head of claim 2 , wherein the base structure further includes a rigid platen to which conductive elements are attached, and the resilience of the flexible layer allows the tufts to move relative to the base structure.

4. The brush head of claim 3 , wherein each of the tufts comprises a conductive surface that is moved into contact with the conductive element when the force exceeds the threshold.

5. 4. The brush head of claim 3, further comprising a conductive layer for one or more of the tufts that is pushed by a corresponding one of the tufts into contact with the conductive element when the force exceeds the threshold.

6. The brush head of claim 3 , wherein the conductive elements are discrete elements and the electrical connections electrically connect the discrete elements.

7. The brush head of claim 6 , wherein the discontinuous elements comprise two planar halves or two raised pads.

8. 10. An electric toothbrush comprising: the brush head of claim 1; and a controller configured to generate a tuft signature representative of the distribution of the force applied across the array of tufts.

9. 9. The electric toothbrush of claim 8, wherein the controller is configured to classify an angle of the brush head relative to a user's teeth depending on the tuft signature.

10. 9. The electric toothbrush of claim 8, wherein the controller is configured to classify the pressure exerted by the brush head against the user's teeth depending on the tuft signature.

11. 9. The electric toothbrush of claim 8, wherein the tuft signatures include a plurality of training tuft signatures and a current tuft signature, the controller is configured to create, during a training process, a signature map that associates each of the training tuft signatures with a particular location in the user's mouth determined based on position data acquired by a position sensor, and the controller is configured, during use, to determine the location of the brush head in the user's mouth by comparing the current tuft signature with the signature map.

12. 12. The electric toothbrush of claim 11, wherein the controller is configured to receive position data from a position sensor and use the position data and the tuft signature to recalibrate or verify the position sensor to a determined location of the brush head in a user's mouth.

13. 1. A method of operating an electric toothbrush, comprising: receiving a force on each of a plurality of tufts of a brush head of the electric toothbrush, the tufts being embedded in a flexible layer; generating, for each of the tufts, a signal representative of the force applied to each of the tufts individually, the signal resulting from a deformation of the flexible layer; and generating a tress signature representative of the distribution of the force applied to the tress. method.

14. 14. The method of claim 13, wherein the tufts are configured as normally open switches movable relative to a base structure of the brush head in response to the force, and wherein generating includes forming an electrical connection with a given one of the tufts to generate the signal when the force exceeds a threshold value for that given one of the tufts.

15. determining from the tuft signature at least one of a location of the brush head within a user's mouth, an angle of the brush head relative to the user's teeth, and a force applied by the user; the tuft signatures include a plurality of training tuft signatures and a current tuft signature, and during a training process a signature map is created that associates each of the training tuft signatures with a particular location within the user's mouth determined based on position data acquired by a position sensor, and during use the location of the brush head within the user's mouth is determined by comparing the current tuft signature with the signature map. The method of claim 13.

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