Patent Publication Number: US-11654008-B2

Title: Personal care system and method

Description:
BACKGROUND 
     Electric toothbrushes are well known from moving a brush head or its components to promote teeth cleaning. Some such toothbrushes move the brush head in an oscillating motion. There is need, however, for an electric toothbrush having an oscillating motion that can adjust smoothly and continuously from one intensity to another without steps or jumping in the oscillation. 
     BRIEF SUMMARY 
     The present invention is directed to a personal care appliance and a method for controlling same. In one aspect, a personal care appliance includes an electric motor having a drive shaft, the electric motor configured to, in response to a voltage signal, oscillate the drive shaft in an oscillatory motion having an oscillation amplitude; and a control circuit comprising, in operable cooperation, a user interface, a processor, a pulse width modulation signal generator, and a power source, the control circuit operably coupled to the electric motor and configured to supply the voltage signal to the electric motor, the voltage signal having a frequency and a duty cycle, the control circuit configured to vary the frequency and the duty cycle of the voltage signal in response to an oscillation adjustment input received from the user interface so that the oscillation amplitude of the drive shaft is varied along a substantially linear rate of change profile relative to the frequency. 
     In another aspect, a method of controlling a personal care appliance comprising an electric motor having a drive shaft and a control circuit comprising, in operable cooperation, a user interface, a processor, a pulse width modulation signal generator, a memory unit, and a power source, the control circuit operably coupled to the electric motor, is disclosed. The method includes generating, with the control circuit, a voltage signal having a frequency and a duty cycle; supplying the voltage signal to the electric motor to oscillate the drive shaft in an oscillatory motion having an oscillation amplitude; and the control circuit varying the frequency and the duty cycle of the voltage signal in response to an oscillation adjustment input received from the user interface so that the oscillation amplitude of the drive shaft is varied along a substantially linear rate of change profile relative to the frequency. 
     In another aspect, a personal care appliance includes an electric motor having a drive shaft, the electric motor configured to, in response to a voltage signal, oscillate the drive shaft in an oscillatory motion having an oscillation amplitude; and a control circuit comprising, in operable cooperation, a user interface, a pulse width modulation signal generator, a processor, a memory unit, and a power source, the control circuit operably coupled to the electric motor and configured to supply the voltage signal to the electric motor, the voltage signal having a frequency and a duty cycle, the control circuit configured to operate the electric motor in accordance with a selected one of the first mode or the second mode in response to a mode selection input from the user interface; wherein when the first mode is selected, the frequency and/or the duty cycle of the voltage signal is varied in response to an oscillation adjustment input received from the user interface so that the oscillation amplitude of the drive shaft is varied along a first rate of change profile relative to the frequency in the first mode; and wherein when the second mode is selected, the frequency and/or the duty cycle of the voltage signal is varied in response to the oscillation adjustment input received from the user interface so that the oscillation amplitude of the drive shaft is varied along a second rate of change profile relative to the frequency in the second mode, the first and second rate of change profiles being different than one another. 
     In another aspect, a method of controlling a personal care appliance comprising an electric motor having a drive shaft and a control circuit comprising, in operable cooperation, a user interface, a processor, a pulse width modulation signal generator, a memory unit, and a power source, the control circuit operably coupled to the electric motor, is disclosed. The method includes initiating a selected one of a first mode or a second mode in response to a mode selection input from the user interface; generating, with the control circuit, a voltage signal having a frequency and a duty cycle in accordance with the selected one of the first mode or the second mode; supplying the generated voltage signal to the electric motor to oscillate the drive shaft in an oscillatory motion having an oscillation amplitude; and varying the frequency and/or the duty cycle of the generated voltage signal in response to an oscillation adjustment input received from the user interface so that the oscillation amplitude of the drive shaft is varied along a first rate of change profile relative to the frequency when in the first mode; and varying the frequency and/or the duty cycle of the generated voltage signal in response to the oscillation adjustment input received from the user interface so that the oscillation amplitude of the drive shaft is varied along a second rate of change profile relative to the frequency when in the second mode, the first and second rate of change profiles being different than one another. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIGS.  1 - 2    are perspective views of a personal care appliance according to one embodiment. 
         FIGS.  3 A-C  are different views of a stem of the personal care appliance of  FIGS.  1 - 2   . 
         FIG.  4    is top view of a stem of the personal care appliance showing the oscillation amplitude for the stem according to one embodiment. 
         FIGS.  5 - 7    are views of a motor of the personal care appliance according to one embodiment. 
         FIG.  8    is block diagram of a control circuit for controlling the oscillation of a stem of a personal care appliance according to one embodiment. 
         FIG.  9    shows graphs of voltage signals for oscillating a drive shaft of a motor of a personal care appliance according to one embodiment. 
         FIG.  10    shows substantially linear rate of change profiles for oscillation amplitude relative to frequency for first and second modes according to one embodiment. 
         FIGS.  11 - 12    show non-linear rate of change profiles for duty cycle relative to frequency for causing the substantially linear rate of change profiles for oscillation in  FIG.  9   . 
     
    
    
     DETAILED DESCRIPTION 
     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
     The description of illustrative embodiments according to principles of the present invention is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description of embodiments of the invention disclosed herein, any reference to direction or orientation is merely intended for convenience of description and is not intended in any way to limit the scope of the present invention. Relative terms such as “lower,” “upper,” “horizontal,” “vertical,” “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description only and do not require that the apparatus be constructed or operated in a particular orientation unless explicitly indicated as such. Terms such as “attached,” “affixed,” “connected,” “coupled,” “interconnected,” and similar refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. Moreover, the features and benefits of the invention are illustrated by reference to the exemplified embodiments. Accordingly, the invention expressly should not be limited to such exemplary embodiments illustrating some possible non-limiting combination of features that may exist alone or in other combinations of features; the scope of the invention being defined by the claims appended hereto. 
     As used throughout, ranges are used as shorthand for describing each and every value that is within the range. Any value within the range can be selected as the terminus of the range. In addition, all references cited herein are hereby incorporated by reference in their entireties. In the event of a conflict in a definition in the present disclosure and that of a cited reference, the present disclosure controls. 
     In the following description, where circuits are shown and described, one of skill in the art will recognize that, for the sake of clarity, not all peripheral circuits or components are shown in the figures or described in the description. Further, the terms “couple” and “operably couple” can refer to a direct or indirect coupling of two components of a circuit. 
     Features of the present inventions may be implemented in software, hardware, firmware, or combinations thereof. The computer programs described herein are not limited to any particular embodiment, and may be implemented in an operating system, application program, foreground or background processes, driver, or any combination thereof. The computer programs may be executed on a single computer or server processor or multiple computer or server processors. 
     Processors described herein may be any central processing unit (CPU), microprocessor, micro-controller, computational, or programmable device or circuit configured for executing computer program instructions (e.g., code). Various processors may be embodied in computer and/or server hardware of any suitable type (e.g., desktop, laptop, notebook, tablets, cellular phones, etc.) and may include all the usual ancillary components necessary to form a functional data processing device including without limitation a bus, software and data storage such as volatile and non-volatile memory, input/output devices, graphical user interfaces (GUIs), removable data storage, and wired and/or wireless communication interface devices including Wi-Fi, Bluetooth, LAN, etc. 
     Computer-executable instructions or programs (e.g., software or code) and data described herein may be programmed into and tangibly embodied in a non-transitory computer-readable medium that is accessible to and retrievable by a respective processor as described herein which configures and directs the processor to perform the desired functions and processes by executing the instructions encoded in the medium. A device embodying a programmable processor configured to such non-transitory computer-executable instructions or programs may be referred to as a “programmable device”, or “device”, and multiple programmable devices in mutual communication may be referred to as a “programmable system.” It should be noted that non-transitory “computer-readable medium” as described herein may include, without limitation, any suitable volatile or non-volatile memory including random access memory (RAM) and various types thereof, read-only memory (ROM) and various types thereof, USB flash memory, and magnetic or optical data storage devices (e.g., internal/external hard disks, floppy discs, magnetic tape CD-ROM, DVD-ROM, optical disk, ZIP™ drive, Blu-ray disk, and others), which may be written to and/or read by a processor operably connected to the medium. 
     In certain embodiments, the present inventions may be embodied in the form of computer-implemented processes and apparatuses such as processor-based data processing and communication systems or computer systems for practicing those processes. The present inventions may also be embodied in the form of software or computer program code embodied in a non-transitory computer-readable storage medium, which when loaded into and executed by the data processing and communications systems or computer systems, the computer program code segments configure the processor to create specific logic circuits configured for implementing the processes. 
     Referring to  FIGS.  1 - 2   , an oral care implement  100  will be described in accordance with an embodiment of the present invention. In the exemplified embodiment, the oral care implement  100  is a powered or electric toothbrush. In other embodiments, the oral care implement may be a manual toothbrush. In still other embodiments, the oral care implement  100  may be other hygienic tools for treating the oral cavity such as a tongue scraper, a gum and soft tissue cleanser, a water pick, an interdental device, a tooth polisher, a specially designed ansate implement having tooth engaging elements, or any other type of implement that is commonly used for oral care. In still other embodiments, the oral care implement  100  may be a personal care appliance instead of an oral care implement. Examples of such personal care appliances include hairbrushes, razors, body scrubbers, skin treatment devices, or the like. The oral care implement  100  generally comprises a handle  200  and a workpiece  300 , which in this embodiment is an oral care refill head  300 . It is to be understood that the inventive concepts discussed herein can be applied to any type of oral care implement or personal care implement unless a specific type of implement is specified in the claims. The structural and functional details of the oral care implement  100  will be provided below in accordance with exemplary embodiments of the present invention. 
     The handle  200  is the portion of the oral care implement  100  that is gripped by a user during use. The oral care refill head  300  is the portion of the oral care implement  100  that performs the cleaning or other hygienic function. The oral care refill head  300  can be detached from the handle  200 , and thus when they are coupled the oral care refill head  300  is detachably coupled to the handle  200 . Thus, the oral care refill head  300  may be detached from the handle  200  and replaced with a new oral care refill head  300  when cleaning elements on the oral care refill head  300  become worn over time. This allows the handle  200  to continue to be used while the oral care refill head  300  is exchanged, which is important because the expensive electronic circuitry is located within the handle  200 . Multiple users can also use the same handle  200  while placing their individual oral care refill heads thereon prior to use. 
     The handle  200  comprises a gripping portion  210  that terminates at a distal end surface  211  and a stem  250  protruding from the distal end surface  211  of the gripping portion  210 . The gripping portion  210  is the part of the handle  200  that is gripped by a user during oral hygiene activities and it may include various buttons, switches, indicators, lights, user controls, or the like to both allow a user to control functionality and operation of the oral care implement  100  and also provide information to the user. For example, the handle  200  may comprise a power button  201  that can power the oral care implement  100  on and off (and provide power to a motor thereof as described in more detail below). 
     The handle  200  may also include a user interface  202  for altering the intensity of brushing. In the exemplified user interface, a mode button  202 C allows the user to change from one intensity mode to another. In the exemplified embodiment, the intensity modes comprise a first mode (e.g., a low intensity mode) and a second mode (e.g., a high intensity mode), and a user may switch between modes by selecting the mode button  202 C. Further, a user may increase or decrease the intensity within a given mode by selecting buttons  202 A and  202 B, respectively. The invention, however, is not so limited. Any number of modes may be used (e.g., low, medium, and high modes). Further, the mode button  202 C may be eliminated and the mode may be changed by alternate means, such as by pressing (quickly or for a long period of time) one or more of the power button  201  and buttons  202 A,  202 B. For example, the mode may be changed by holding or quickly pressing the power button  201 , or by pressing buttons  202 A,  202 B at the same time, or by pressing one of the buttons  202 A,  202 B quickly or slowly. In other embodiments, pressing the up button  202 A repeatedly will cause a brush in a low mode to increase its brushing intensity in the low mode until it enters a higher mode, and continued pressing of the up button  202 A would increase the intensity in the higher mode. Similarly, pressing the down button  202 B repeatedly will cause a brush in a high mode to decrease its brushing intensity in the high mode until it enters a lower mode, and continued pressing of the down button  202 B would decrease the intensity in the lower mode. Note that the user interface is not limited to the buttons shown in  FIG.  1   . It may comprise any type of interface, such as a button, dial, or screen. In yet other embodiments, the implement  100  may wirelessly communicate with an electronic device, such as a smartphone. For example, the user interface may be a touchscreen or another interface of the electronic device. In yet other embodiments, the mode may be altered by sensing a shaking or other movement of the brush. 
     The handle  200  may also include various indicators  203  that may be activated (e.g., lights that may be illuminated) to inform a user when the battery is low, when the user is brushing with too much pressure, when the oral care implement  100  is powered on, and various other information that may be helpful to a user. 
     As noted above, the exemplified handle  200  houses the electronic components associated with the oral care implement  100 . The exemplified gripping portion  210  of the handle  200  houses a motor  130  and control circuit  150  discussed in detail below (see  FIGS.  5 - 7   ). The stem  250  is operably coupled to the motor  130  and may form a portion of a drive shaft of the motor  130  or the stem  250  may be operably coupled to a drive shaft of the motor  130 . For example, the stem  250  may form a distal portion of the drive shaft of the motor  130 . In some embodiments, the stem  250  may be a plastic housing or the like that surrounds the drive shaft of the motor  130  with the plastic housing that surrounds the drive shaft forming the coupling between the handle  200  and the oral care refill head  300 . In the exemplified embodiment, the stem  250  is operably coupled to the motor  130  and due to that coupling, upon activating the motor  130  by powering on the oral care implement  100 , the motor&#39;s drive shaft will impart movement to the stem  250  thereby causing the stem  250  to rotate, oscillate, or the like. 
       FIGS.  3 A-C  and  4  show the stem separate from the implement  100 .  FIG.  4    shows the oscillation of the distal end  252  of the stem  250 . The rotation about point C causes the stem to have a swing angle  250 A. This swing or rotation is a type of oscillation whose swing angle is a type of oscillation amplitude. The invention, however, is not so limited. In other embodiments, the oscillation amplitude may be a magnitude of a different type of oscillating movement, such as a back-and-forth non-rotational movement. 
     Returning to the exemplified embodiment, when the oral care refill head  300  is coupled to the handle  200 , the oscillation of the stem  250  will cause oscillation of the oral care refill head  300 , or at least the cleaning elements thereof, to optimize the cleaning performance. The stem  250  forms the feature of the handle  200  that couples to the oral care refill head  300  and also imparts movement to the cleaning elements of the oral care refill head  300 . 
     As discussed in further detail in  FIG.  8   , there is a control circuit  150  in the handle  200 . In the exemplified embodiment, the control circuit  150  comprises a printed circuit board (not shown) having several electronic components thereon in electrical communication with one another. The control circuit  150  may further include components located elsewhere. For example, the control circuit  150  may comprise or be in communication with the user interface  202  for adjusting the oscillation amplitude and power button  201 . The intensity button  202 C may be in operable coupling with the control circuit  150  so that pressing the intensity button  202 C causes a change in the mode (e.g., from a low intensity mode to a high intensity mode). Further, the buttons  202 A,  202 B may be in operable communication with the control circuit so that pressing them causes a gradual increase or decrease in the motor intensity or speed. As discussed above, in other embodiments, the mode can be switched by other means. 
     The indicators  203  may be formed by transparent portions of the handle  200  that are aligned with light sources of the control circuit  150  that illuminate when different thresholds are met. For example, when the battery power is below a threshold, a low battery light may illuminate and be seen through a transparent portion of the handle  200  (such as an icon that is readily identifiable as a battery power indicator). Furthermore, when excessive pressure is felt during brushing, a high pressure light may illuminate. Of course, other indicators  203  may be used to provide different indications to a user as desired. The control circuit  150  may comprise a controller or processor that receives input from the various actuators and transmits instructions to the power source  130 , motor  140 , and various light sources to activate and deactivate accordingly. However, a processor or controller is not needed in all embodiments and in other embodiments activating and deactivating the various actuators opens and closes a switch which either causes power to be supplied to or prevents power from being supplied to the various components for activation and deactivation thereof. The various actuators that may form part of the control circuit  150  may be various switches including trigger switches, contact switches, conductive switches, throw switches, push button switches, pressure switches, toggle switches, or other mechanical type switches. In other embodiments electronic switches could be used in place of the mechanical type switches. 
     Turning again to  FIGS.  1  and  2   , the oral care refill head  300  comprises a head portion  310  and an attachment portion  320 . The head portion  310  comprises an oral treatment tool (or head structure)  311  having a front surface  312  and a rear surface  313 . Furthermore, the head portion  310  comprises a plurality of tooth cleaning elements  314  extending from the front surface  312  of the oral treatment tool  311 . The plurality of tooth cleaning elements  314  may comprise bristle tufts, filament bristles, fiber bristles, nylon bristles, polybutylene terephthalate (PBT) bristles, spiral bristles, rubber bristles, elastomeric protrusions, flexible polymer protrusions, lamella, combinations thereof, and/or structures containing such materials or combinations. Thus, any combination of these elements may be used to form one or more of the tooth cleaning elements  314  in some embodiments. Furthermore, where bristles are used for one or more of the tooth cleaning elements  314 , such bristles can be tapered, end-rounded, spiral, or the like. The tooth cleaning elements  314  may be coupled to the head portion  310  using any known techniques such as staples, anchor-free tufting, in-mold tufting, PTT, or the like. In the exemplified embodiment, the tooth cleaning elements  314  comprises a plurality of tufts of bristles arranged in a particular pattern on the head portion  310 . Of course, the particular pattern of the tooth cleaning elements  314  is not to be limiting of the present invention unless specifically claimed as such. 
     Furthermore, in the exemplified embodiment there is a soft tissue cleaner  315  positioned on the rear surface  313  of the head portion  310  of the oral care refill head  300 . The soft tissue cleaner  315  may be an elastomeric material such as thermoplastic elastomer that is injection molded onto the rear surface  313  of the head portion  310 . The soft tissue cleaner  315  may include a pad portion  316  and a plurality of protuberances  317  protruding from the pad portion  316  (see  FIG.  3    for best illustration of pad portion  316  and protuberances  317 ). Alternatively, the soft tissue cleaner  315  may include ridges, depressions, nubs, or any desirable feature for cleaning and/or scraping the tongue and its papillae. 
     Referring to  FIGS.  3 A-C , the stem  250  as well as its interaction with various components of the oral care refill head  300  will be described. The exemplified stem  250  comprises a proximal stem section  253  that is located within the interior of the gripping section  210  of the handle  200  when the stem  250  is coupled to the handle  200 , a base stem section  254 , and a distal stem section  255 . The proximal stem section  253  may form the drive shaft of the motor  140  in some embodiments. In other embodiments, stem  250  may comprise only the base stem section  254  and the distal stem section  255 , which form a distal portion of a drive shaft of the motor  140  with the remainder of the drive shaft of the motor  140  being formed by the proximal stem section  253 . The base stem section  254  is located between the proximal stem section  253  and the distal stem section  255 . As noted above, the proximal stem section  253  is located within the interior of the handle  200 , the base stem section  254  protrudes from and is adjacent to the gripping portion  210  of the handle  200 , and the distal stem section  255  extends from the base stem section  254  to the distal end  252 . In some embodiments, the stem  250  may comprise only the portions thereof that extend from the distal end surface  211  of the gripping portion  210  of the handle  200  (i.e., the base stem section  254  and the distal stem section  255 ). 
     The stem  250  comprises an annular groove  256  located in the proximal stem section  253 . The annular groove  256  is configured to mate with a member of the handle  200 . The stem  250  also comprises a locking depression  257  located along the base stem section  254  of the stem  250  for engaging the refill head  300 . In the exemplified embodiment, the locking depression  257  is an annular depression  257  that extends around the entire circumference of the stem  250 . Thus, the locking depression  257  extends 360 degrees around the stem  250 . However, in other embodiments the locking depression  257  may extend along a part but not the entirety of the circumference of the stem  250 . In the exemplified embodiment, the locking depression  257  has a V-shaped cross-section, although the invention is not to be so limited in all embodiments and the cross-sectional shape of the locking depression  257  could be modified so long as it is configured to matingly engage the refill head  300 . The exemplified stem  250  is configured for detachable coupling to the refill head  300 . 
     The distal stem section  255  of the stem  250  comprises a first radial planar shoulder  260  located on a first side of the stem axis C-C and a second radial planar shoulder  261  located on a second side of the stem axis C-C that is opposite the first side of the stem axis C-C. The distal stem section  255  of the stem  250  further comprises a first planar surface  262  extending from the first radial planar shoulder  260  to the distal end  252  and a second planar surface  263  extending from the second radial planar shoulder  261  to the distal end  252 . The first planar surface  262  and the first radial planar shoulder  260  are located on a first side of the stem axis C-C and the second planar surface  263  and the second radial planar shoulder  261  are located on a second side of the stem axis C-C. The first and second planar surfaces  262 ,  263  are oriented substantially parallel to one another and to the stem axis C-C. (the term substantially allowing for a range of plus or minus 5°). In some embodiments, the first and second planar surfaces  262 ,  263  may be exactly parallel to one another and to the stem axis C-C. The first and second planar surfaces  262 ,  263  are flat faces on the stem  250  which is otherwise round. Thus, the portions of the outer surface of the stem  250  between the first and second planar surfaces  262 ,  263  along the distal stem section  255  are round or arcuate. 
     The first and second radial planar shoulders  260 ,  261  are aligned along the stem axis C-C. Thus, there is no transverse axis (oriented perpendicular to the stem axis C-C) that would intersect any part of the first radial planar shoulder  260  and also intersect a part of the second radial planar shoulder  261 . Rather, the first and second radial planar shoulders  260 ,  261  are located at entirely different axial heights along the stem  250 . Stated another way, the first radial planar shoulder  260  extends from a first end  264  to a second end  265 , the first end  264  being closer to the proximal end  251  than the second end  265 . The second radial planar shoulder  261  extends from a first end  266  to a second end  267 , the first end  266  being closer to the proximal end  251  than the second end  267 . The second end  265  of the first radial planar shoulder  260  is located closer to the proximal end  251  of the stem  250  than the first end  266  of the second radial planar shoulder  261  (or, the first end  266  of the second radial planar shoulder  261  is located closer to the distal end  252  of the stem  250  than the second end  265  of the first radial planar shoulder  260 ). 
       FIGS.  5 - 7    show a motor  130  and its components according to one embodiment. The exemplified motor  130  utilizes an electromagnetic coil and permanent magnets coupled to the drive shaft as the rotor. While a brief description of the motor  130  is provided below, U.S. Pub. No. 2018263743 is incorporated herein by reference in its entirety for further information on the exemplified motor. The invention is not limited to the exemplified motor, however, as other types of motors may be utilized to carry out the invention. 
     The exemplified motor  130  includes a motor housing  131 , a stator core  132  having at least two poles fixedly installed in the stator housing  131  symmetrically, an electromagnetic coil  133  wound around the stator core  132 , and an insulating coil holder  134  for insulating the stator core  132  from the coil winding  133 . The motor  130  further includes at least two pairs of permanent magnets  135  cooperating with the stator core  132 . The permanent magnets  135  are all fixedly connected to a periphery of a shaft coupling  136 , and the shaft coupling  136  is fixedly connected to a drive shaft  137 . When the motor  130  is activated by a voltage signal, the coil winding  133  is electrified to generate a magnetic field at the stator core  132 , the magnetic field drives the permanent magnets  135  to drive the shaft coupling  136  to rotate, and in turn the motor shaft  137  is driven to move. The angle of rotation  250 A of the drive shaft is shown in  FIG.  4   , and is a type of oscillation amplitude. The charge of the coil windings  133  are alternated, thereby causing an oscillatory rotation of the motor shaft  137  through the swing angle. The exemplified motor  130  does not include any spring elements to create a bias on the motor shaft  137 . Rather, the oscillatory movement of the motor shaft  137  is entirely created by alternating the polarity of the magnetic field generated by the coil windings  133 . As will be discussed in further detail below with respect to  FIGS.  8 - 9   , in the exemplified embodiment the coil is energized by a first voltage signal V 1  at a first motor terminal  130 - 1  of the coil  133  and a second voltage signal V 2  at a second motor terminal  130 - 2  of the coil causing a resulting voltage  406  across the terminals  130 - 1 ,  130 - 2  that alternates between positive and negative voltage, thus causing the oscillation of the drive shaft. The motor  130  further includes end cap  138  and ball bearing  139 . 
       FIG.  8    is block diagram of a control circuit  150  for controlling the oscillation of a stem of a personal care appliance according to one embodiment. The control circuit is designed to be coupled to the motor terminals  130 - 1 ,  130 - 2  as discussed above to energize the electromagnetic coil  133  by one or more voltage signals. The exemplified control unit  150  includes a motor driver  152  for driving the coil  133  through the motor terminals  130 - 1 ,  130 - 2 . The motor driver outputs voltages V 1  and V 2 , which are coupled to the terminals  130 - 1 ,  130 - 2 , respectively. The motor driver is coupled to a power source  140 . In the exemplified embodiment, the power source is a 3.5V battery rechargeable by induction, though the invention is not limited to a particular type of power source. The motor driver  152  receives pulse width modulated signals PWM- 1  and PWM- 2  from a processor  151  that includes a pulse width modulation signal generator. Pulse width modulation is well known, and therefore not described here in detail Any type of pulse width modulation may be used, and it other embodiments the voltage signal need not be pulse width modulated. Further, the pulse width modulation may be altered by an input received at the user interface  202 , such as the user interface  202  in  FIG.  1    where a user may change the intensity within a given mode and/or may switch between a high intensity mode and a low intensity mode. The processor  151  is configured to receive the input from the user interface  202  and alter the pulse width modulated signals as necessary to alter the brushing intensity as desired by the user. 
       FIG.  9    shows graphs of voltage signals for oscillating a drive shaft of a motor of a personal care appliance according to one embodiment. Waveform  402  represents the first PWM signal PWM- 1  that is provided to the motor driver  152 . Waveform  404  represents the second PWM signal PWM- 2  that is provided to the motor driver  152 . In this embodiment, each PWM signal has a low of 0V and a high of 2.5V, and the duty cycle is 80%, though the invention is not so limited. By alternating the on time for the respective signals, the output of the motor driver  152  is enabled to rotate the drive shaft in opposing clockwise and counterclockwise directions. Due to the output of the motor driver  152  in V 1  and V 2  (see  FIG.  8   ), the resulting voltage across the motor terminals  130 - 1 ,  130 - 2  is shown by waveform  406 . The positive portion of the waveform  406  represents the rotation of the drive shaft in one direction, while the negative portion of the waveform represents the rotation of the drive shaft in the opposite direction. The voltage across the motor terminals in a working cycle is about 3.5V DC. The waveforms shown in  FIG.  9    are only examples, and a variety of different voltage signals could be used to oscillate the motor. 
       FIG.  10    shows substantially linear rate of change profiles  408 ,  410  for oscillation amplitude relative to frequency for first and second modes according to one embodiment. As stated above, in changing the brushing intensity of the implement, such as the oscillation amplitude, there is a desire that the transition is smooth and continuous without steps or jumping. To accomplish this, the control circuit must vary the frequency and/or the duty cycle of voltage signal received by the electric motor such that the oscillation amplitude of the drive shaft is varied along a substantially linear rate of change profile relative to the frequency. As used herein, the term “substantially linear” shall mean that the profile is within an area of plus or minus 5% from a trend line.  FIG.  10    shows such linear rate of change profiles  408 ,  410 . Specifically, profile  408  is a substantially linear rate of change profile for a first mode (e.g., a low intensity mode), and profile  410  is a substantially linear rate of change profile for a second mode (e.g., a high intensity mode). In this example, the first rate of change profile  408  has a first slope and the second rate of change profile  410  has a second slope that is different from the first slope. Similarly, the first and second rate of change profiles  408 ,  410  have different average rates of change (e.g., when the profile is not linear). It is noted that invention is not so limited. Further, while  FIG.  10    shows only two modes (high and low), in other embodiments there may be more than two modes. Further, there may alternately be a single mode having a single substantially linear rate of change profile. 
     The exemplified first rate of change profile  408  has (i) a first starting point  408 A corresponding to a first minimum frequency (shown in Hertz) and a first minimum oscillation amplitude (shown in degrees of swing angle) for the first mode, and (ii) a first endpoint  408 B corresponding to a first maximum frequency and a first maximum oscillation amplitude for the first mode. Similarly, the exemplified second rate of change profile  410  has (i) a second starting point  410 A corresponding to a second minimum frequency and a second minimum oscillation amplitude for the second mode, and (ii) a second endpoint  410 B corresponding to a second maximum frequency and a second maximum oscillation amplitude for the second mode. In the exemplified embodiment, the second minimum frequency is greater than the first maximum frequency, and the second minimum oscillation amplitude is greater than the first maximum oscillation amplitude. Further, the difference between the first maximum oscillation amplitude and the first minimum oscillation amplitude is less than a difference between the second maximum oscillation amplitude and the second minimum oscillation amplitude. The invention, however, is not limited to the foregoing features. For example, the profiles may have alternative starting and ending points, and need not be linear. 
       FIGS.  11 - 12    shows that, to achieve the substantially linear rate of change profiles of  FIG.  10   , the control circuit can use non-linear rate of change profiles for duty cycle relative to frequency.  FIG.  11    shows a non-linear rate of change profile  412  for the first mode. By altering duty cycle with respect to frequency according to this non-linear profile  412  for the first mode when altering the oscillation amplitude, the oscillation amplitude is able to change with frequency according the substantially linear profile  408  shown in  FIG.  10   . Similarly, by altering duty cycle with respect to frequency according to non-linear profile  420  for the second mode when altering the oscillation amplitude, the oscillation amplitude is able to change with frequency according the substantially linear profile  410  shown in  FIG.  10   . As shown in  FIG.  11   , and corresponding with first mode profile  408  of  FIG.  10   , the non-linear profile  412  begins at a 5.5 degrees oscillation and ends at 12.5 degrees oscillation. Similarly, in  FIG.  12   , corresponding with second mode profile  410  of  FIG.  10   , the non-linear profile  420  begins at 16.2 degrees oscillation and ends at 27.2 degrees oscillation. 
     As shown in  FIG.  11   , the non-linear rate of change profile  412  comprises (1) a first section  414  corresponding to a first range of the frequency; (2) a second section  416  corresponding to a second range of the frequency; and (3) a third section  418  corresponding to a third range of the frequency, the second range of the frequency located between the first and third ranges of the frequency and greater than the first range of the frequency. The first section  414  of the non-linear rate of change profile  412  has an average rate of change that is less than an average rate of change of the third section  418 . 
     As shown in  FIG.  12   , the non-linear rate of change profile  420  similarly comprises (1) a first section  422  corresponding to a first range of the frequency; (2) a second section  424  corresponding to a second range of the frequency; and (3) a third section  426  corresponding to a third range of the frequency, the second range of the frequency located between the first and third ranges of the frequency and greater than the first range of the frequency. By contrast to  FIG.  11   , however, the first section  422  of the non-linear rate of change profile  420  has an average rate of change that is greater than an average rate of change of the third section  426 . For both  FIG.  11    and  FIG.  12    (both first and second modes), however, the second section  416 ,  424  of the non-linear rate of change profile  412 ,  420  has an average rate of change that is between the average rate of change of the third section and the average rate of change of the first section. Note that the invention is not limited to the rate of change profiles shown in  FIGS.  10 - 12   , as various other frequencies, duty cycles, and oscillation amplitudes may be used taking different waveforms of different rates of change. 
     While the invention has been described as a system or apparatus, it may also be embodied as a method. In one embodiment, a method of controlling a personal care appliance comprising an electric motor having a drive shaft and a control circuit comprising, in operable cooperation, a user interface, a processor, a pulse width modulation signal generator, a memory unit, and a power source, the control circuit operably coupled to the electric motor, is disclosed. The method comprises generating, with the control circuit, a voltage signal having a frequency and a duty cycle; supplying the voltage signal to the electric motor to oscillate the drive shaft in an oscillatory motion having an oscillation amplitude; and the control circuit varying the frequency and the duty cycle of the voltage signal in response to an oscillation adjustment input received from the user interface so that the oscillation amplitude of the drive shaft is varied along a substantially linear rate of change profile relative to the frequency. 
     In another embodiment, a method of controlling a personal care appliance comprising an electric motor having a drive shaft and a control circuit comprising, in operable cooperation, a user interface, a processor, a pulse width modulation signal generator, a memory unit, and a power source, the control circuit operably coupled to the electric motor, is disclosed. The method comprises initiating a selected one of a first mode or a second mode in response to a mode selection input from the user interface; generating, with the control circuit, a voltage signal having a frequency and a duty cycle in accordance with the selected one of the first mode or the second mode; supplying the generated voltage signal to the electric motor to oscillate the drive shaft in an oscillatory motion having an oscillation amplitude; and varying the frequency and/or the duty cycle of the generated voltage signal in response to an oscillation adjustment input received from the user interface so that the oscillation amplitude of the drive shaft is varied along a first rate of change profile relative to the frequency when in the first mode; and varying the frequency and/or the duty cycle of the generated voltage signal in response to the oscillation adjustment input received from the user interface so that the oscillation amplitude of the drive shaft is varied along a second rate of change profile relative to the frequency when in the second mode, the first and second rate of change profiles being different than one another. 
     In yet another embodiment, a toothbrush may include a mode that combines two or more other modes. In one embodiment, the toothbrush has four selectable modes, a low intensity mode, a medium intensity mode, a high intensity mode, and a combination mode. In the combination mode, the toothbrush automatically cycles through each of the low, medium, and high intensity modes without further input from the user. In another embodiment, one of the selectable modes in a pulsing mode in which the motor&#39;s power rapidly increases and then decreases, and in the combination mode the toothbrush cycles through the non-pulsing modes and the pulsing mode. Though as discussed below, the invention is not limited to a particular combination of modes. 
     Stated broadly, the invention may be understood as a toothbrush comprising a toothbrush head; an electric motor coupled to a power source, the electric motor comprising a drive shaft and configured to, in response to a voltage signal, impart a motion upon the drive shaft; a handle comprising a stem operably coupled to the toothbrush head and the drive shaft, wherein the motion of the drive shaft is imparted to the stem, and the stem imparts the motion to the refill toothbrush head; a user interface for receiving from a user a selection from among a plurality of modes, the plurality of modes comprising a first mode having a first operating characteristic of the motor; a second mode having a second operating characteristic of the motor different from the first operating characteristic; and a third mode in which the motor automatically transitions from one of the first mode and the second mode to the other of the first mode and the second mode without further user input; and a processor operably coupled to the user interface and the motor, the processor configured to alter the voltage signal supplied to the motor based on which of the plurality of modes is selected. 
     In one embodiment, the operating characteristics are different powers supplied to the motor. In this embodiment, the first operating characteristic comprises a first power supplied to the motor, and the second operating characteristic comprises a second power supplied to the motor, the first power being different from the second power. Additional modes could have additional different powers. The operating characteristics could alternatively (or in addition) be a frequency of the oscillation of the motor. In this embodiment, the first operating characteristic would comprise a first frequency of the oscillation of the motor, and the second operating characteristic would comprise a second frequency of the oscillation of the motor, the first frequency being different from the second frequency. An operating characteristic could also include characteristics of a pulsing of the motor, the pulsing causing a power supplied to the motor to repeatedly increase and then decrease. For example, in a combination mode the toothbrush could automatically cycle through pulsing modes of different intensities. In other embodiments, in a combination mode the toothbrush could cycle though between one or more pulsing modes and one or more non-pulsing modes. In one embodiment, at least one of the first operating characteristic and the second operating characteristic comprises a pulsing of the motor wherein a power supplied to the motor repeatedly increases and then decreases. In another embodiment, there are two or more non-pulsing modes (e.g., a first mode and a second modes, a combination mode (e.g., a third mode), and a pulsing mode (e.g., a fourth mode). In the combination mode the motor automatically transitions to each of the first (non-pulsing) mode, the second (non-pulsing) mode, and the fourth (pulsing) mode without further user input. The transitioning between the different modes (pulsing and non-pulsing) can occur in any order. Further, there can be any number of pulsing and non-pulsing modes. 
     The components of the toothbrush may have any of the features discussed herein. For example, the toothbrush head may be a refill toothbrush head. Further, the motor may form part of the handle, and the stem may be configured for detachable coupling with the toothbrush head. Further, while in the first mode or the second mode, a control circuit may alter a frequency and/or a duty cycle of the voltage signal in response to an oscillation adjustment input received from the user interface so that an oscillation amplitude of the drive shaft is varied along a substantially linear rate of change profile relative to the frequency by any of the methods described herein. 
     Further, the toothbrush may be used as part of a method for controlling an electric toothbrush, the method comprising receiving from the user, by the user interface, a selection of a combination mode (sometimes referred to as a “third mode”) from a plurality of modes, the plurality of modes comprising a first mode having a first operating characteristic of the motor; a second mode having a second operating characteristic of the motor; and the combination mode. Upon receiving the selection of the third mode, the voltage signal supplied to the motor is altered to automatically cycle the motor from one of the first mode and the second mode to the other of the first mode and the second mode without further user input. 
     While the inventions have been described with respect to specific examples including presently preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and techniques. It is to be understood that other embodiments may be utilized and structural and functional modifications may be made without departing from the scope of the present inventions. Thus, the spirit and scope of the inventions should be construed broadly as set forth in the appended claims.