Abstract:
An electric, motorized toothbrush includes a switch that has an “automatic” position. The “automatic” mode provides for intermittent motorized operation, which is dependent upon application of an external force. Various embodiments allow for the force to be exerted either on the toothbrush handle, such as when it is gripped by the user, or on the brush head itself—e.g., when the brush head contacts the user&#39;s teeth. A substantially hollow housing allows for placement of battery, motor, gears, and linkages to facilitate motorized movement of the brush head.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an electric toothbrush with a multi-position switch allowing for an automatic mode of operation.  
           [0003]    2. Background Art  
           [0004]    Use of electric, motorized toothbrushes used as an aid in cleansing teeth is well known. Typically these toothbrushes employ rotating, reciprocating, or oscillating motion, or a combination thereof, to effectuate the cleaning process.  
           [0005]    A feature commonly found on these toothbrushes is a sliding on/off switch located on or near the handle portion of the toothbrush. The primary feature of such a switch is that it remains either in the “on” position or the “off” position until the user manually changes it. With such a switch, the user has a limited number of choices. The toothbrush motor can be engaged prior to the brush head being placed in the mouth, or the user can wait until the brush head is placed within the mouth before engaging the motor. Both of these choices have inherent undesirable consequences.  
           [0006]    When the user engages the motor prior to placing the brush head in the mouth, the rapid movement of brush head may cause the toothpaste to be shaken off the bristles. Conversely, if the user waits until the brush head is inside the mouth, and in particular in contact with the teeth, it may be difficult to engage the switch, depending on its position relative to the user&#39;s hand.  
           [0007]    Accordingly, it is desirable to provide an improved electric, motorized toothbrush that overcomes the above referenced shortcomings of prior art toothbrushes, by providing an automatic mode of operation.  
         DISCLOSURE OF THE INVENTION  
         [0008]    The present invention provides an electric, motorized toothbrush that can be used in an “automatic” mode. The automatic mode allows the user to insert the brush head into the user&#39;s mouth before the motor is engaged and the brush head starts moving. Engagement of the motor is accomplished by one of a number of methods, each of which utilizes an operator sensitive switch located within the toothbrush housing. One method merely requires the user to bring the brush head into contact with one or more teeth; here, the downward force on the brush head actuates the switch. Another method relies on the force generated by the user&#39;s grip to actuate the switch and start the motor. Yet another method involves the use of sensors in the handle such that the presence of the user&#39;s hand actuates the switch that engages the motor. The rotation of the motor, through various mechanical linkages, causes the brush head to oscillate, facilitating tooth cleaning.  
           [0009]    In a preferred embodiment, the toothbrush has a two-piece housing in which most of the components are located. The housing contains a handle portion and a head portion, connected by a neck portion. The handle portion contains a compartment for a plurality of batteries, held in place and electrically connected by an end cap. Also within the handle portion is a first switch, having an “off” position and an “automatic” position.  
           [0010]    A plurality of gears are operatively connected between the motor and a connecting arm. A spur gear, connected to the motor shaft, drives a ring gear which has an integral crank pin. A connecting arm is operatively connected between the crank pin and a shaft, the shaft being located substantially within the neck portion. In operation, this mechanism resembles a typical slider crank.  
           [0011]    One end of the shaft is located in the head portion of the housing, and is operatively connected to a pinion which is attached to a brush head shaft located on the base side of the brush head. The pinion interfaces with a rack located within the head portion of the housing, thereby facilitating movement of the brush head.  
           [0012]    In the preferred embodiment, a second switch is located substantially within the neck portion of the housing. This switch is characterized by two contact plates. The contact plates are not normally electrically connected; this keeps the electric circuit open. When a force is exerted on the brush head—e.g., when the brush head is in contact with the user&#39;s teeth—the two contact plates electrically connect, the circuit is closed, and the motor is engaged.  
           [0013]    In an alternative embodiment, the second switch is located in the handle portion of the toothbrush. Here, the user squeezes a compressible portion of the handle, thereby closing the second switch. Different types of switches can be employed for this purpose, but the end result is the same. The motor will not rotate and the brush head will not move until the user squeezes the handle and actuates the second switch.  
           [0014]    Another embodiment of the present invention also places the second switch in the handle portion; however, in this embodiment, sensors on the outside of the handle detect the presence of the user&#39;s hand. Hence, the user need not apply a gripping force to the handle to actuate this switch, rather, mere contact with the sensors closes the switch and completes the circuit.  
           [0015]    In each of these embodiments, the first switch can be a three-position switch instead of the two-position switch described above. The use of a three-position switch adds as an option, a continuous “on” mode of operation. That is, the toothbrush could still be used in an “automatic” mode, or turned off completely, but the addition of the continuous “on” mode of operation would allow the toothbrush to be used in the manner of conventional motorized toothbrushes. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 shows a simplified descriptive side view of an electric toothbrush in accordance with the present invention.  
         [0017]    [0017]FIG. 2 shows a simple wiring schematic for the toothbrush shown in FIG. 1;  
         [0018]    [0018]FIG. 3 shows an exploded view of the toothbrush shown in FIG. 1;  
         [0019]    [0019]FIG. 4 shows a fragmentary sectional view of an alternative embodiment of the present invention;  
         [0020]    [0020]FIGS. 5A and 5B show Detail A of FIG. 4;  
         [0021]    [0021]FIG. 6 shows a plan view of the toothbrush shown in FIG. 4.  
         [0022]    [0022]FIG. 7 shows a plan view of a third embodiment of a toothbrush in accordance with the present invention;  
         [0023]    [0023]FIG. 8 shows a fragmentary sectional view of a fourth embodiment of the present invention;  
         [0024]    [0024]FIG. 9 shows a fragmentary sectional view of a fifth embodiment of the present invention;  
         [0025]    [0025]FIG. 10 shows a descriptive side view an a sixth embodiment of the present invention;  
         [0026]    [0026]FIG. 11 shows a simple wiring schematic for the toothbrush shown in FIG. 10;  
         [0027]    [0027]FIG. 12 shows a simple wiring schematic that can be used with any of the various toothbrush embodiments.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0028]    [0028]FIG. 1 shows a simplified descriptive side view of an electric toothbrush  10  in accordance with the present invention. Switch button  12  slides into one of two positions: “off” or “automatic”. While in the automatic mode, motor  14  is engaged only when a force (F) is exerted on the brush head  16 . This force causes a slight movement of the brush head  16  in the direction of the force. Because of this movement, a switch  18  is actuated, an electric circuit is completed, and current flows from batteries  20  to motor  14 . The motor  14  transmits power to brush head  16  through a series of mechanical linkages, shown in detail in FIG. 3.  
         [0029]    [0029]FIG. 2 shows a simple wiring schematic  30  of a circuit for the toothbrush shown in FIG. 1. Motor  32  is electrically connected between a power source  34  and a switch  36 . When switch  36  is in the “off” position, the circuit is open and there is no voltage across motor  32 . When switch  36  is in the “automatic” position, control of motor  32  is transferred to switch  38 . While operating in the automatic mode, the motor  32  is only engaged when a force (F) is applied to switch  38 . Switch  38  can be located in various locations within the toothbrush housing, such as in the handle or under the brush head.  
         [0030]    [0030]FIG. 3 shows an exploded view of an electric toothbrush  50  in accordance with the present invention. A two-piece housing comprises a bottom housing  52  and a top housing  54 . The housing has a handle portion  56 , a neck portion  58 , and a head portion  60 . Within the handle portion  56  is a battery compartment  62 . Batteries  64  are located within the battery compartment  62  and are electrically connected to each other by a battery connector  66 . The batteries  64  and battery connector  66  are held in place by an end cap  68 .  
         [0031]    Also within the handle portion  56  are battery plates  70  and  72  which connect to the positive  74 A and negative  74 B battery terminals, respectively. Switch button plate  76 , is actuated using switch button  78  and switch cover  80 . To facilitate use of the toothbrush in the automatic mode, a first contact plate  82  and a second contact plate  84  are located substantially within the neck portion of the housing. First contact plate  82  is electrically connected to switch button plate  76  via a first wire  86 , and second contact plate  84  is electrically connected to negative battery plate  72  via a second wire  88 .  
         [0032]    When switch button  78  is in the “off” position, switch button plate  76  does not contact negative terminal  74 B. When switch button  78  is in the “automatic” position, switch button plate  76  is in contact with negative terminal  74 B, but not the negative battery plate  72 . For current to flow to motor  74 , when switch button  78  is in the automatic position, it is therefore necessary for first contact plate  82  and second contact plate  84  to be electrically connected.  
         [0033]    Motor  74  is mounted inside handle portion  56  by means of motor mount  90 . When current flows to motor  74 , motor shaft  74 C rotates, causing rotation of spur gear  92  which is mounted on motor shaft  74 C. Spur gear  92  meshes with ring gear  94  which is provided with an eccentric crank pin  95 . Crank pin  95  is operatively connected to a pivot on the first end of connecting arm  96 . The second end of connecting arm  96  is pivotally connected to shaft  98 , which is held in alignment by bearing  100 . Electrical components are protected from contact with liquid by seal  102 . In operation, as ring gear  94  rotates, eccentric crank pin  95  and the first end of connecting arm  96  rotate. This causes the second end of the connecting arm  96  and shaft  98  to translate axially in a typical slider crank manner.  
         [0034]    Pinion  104  is operatively connected to shaft  98  and is attached to brush head shaft  106 A. Rack  108  is securely mounted inside the neck portion  60 . As shaft  98  reciprocates, the interaction of pinion  104  and rack  108  causes brush head  106  to translate and rotate simultaneously. Brush head shaft  106 A is integrally connected to brush head base  106 B. Brush head bristles  106 C are mounted on brush head base  106 B, on the side opposite brush head shaft  106 A.  
         [0035]    Axial pressure on brush head bristles  106 C causes a deflection of shaft  98  in the direction of the bottom housing  52 . Shaft  98 , in constant contact with plate  84 , then moves a short distance until it also contacts plate  82 ; the two contact plates are thereby electrically connected. The electrical connection of the first contact plate  82  with the second contact plate  84 , has no effect if switch button  78  is in the “off” position. However, when switch button  78  is in the “automatic” position, the electrical connection of the two contact plates completes the electric circuit that allows current to flow to motor  74 . This means that when switch button  78  is in the “automatic” position, motorized movement of brush head  106  is predicated upon an axial force being applied to brush head  106 .  
         [0036]    Referring to FIG. 4, an electric toothbrush  150  is shown in accordance with an alternative embodiment of the present invention. Switch button  152  slides into one of two positions: “off” or “automatic”. While in the automatic mode, motorized movement of brush head  154  occurs only when a force (F) is exerted on the compressible portion  156  of the tooth brush handle  158 . This force causes magnet  160  to move in close proximity to switch plates  162 . When magnet  160  gets within a critical distance of switch plates  162 , the plates contact each other, thereby engaging the drive motor (not shown).  
         [0037]    The magnetic switch mechanism shown in FIG. 4 in circle A, is shown in detail in FIGS. 5A and 5B. Normally, the switch is open; that is, magnet  160  is far enough away from magnetic plate  162 A such that non-magnetic plate  162 B does not contact plate  162 A. After force (F) is applied to the compressible portion  156  of the toothbrush handle  158 , and the distance between magnet  160  and magnetic plate  162 A drops below the minimum critical gap  164 , plate  162 A is drawn toward magnet  160  such that it contacts plate  162 B.  
         [0038]    [0038]FIG. 6 shows a plan view of toothbrush  150  with a one-piece compressible portion  156 . A third embodiment, shown in FIG. 7, uses a two-piece compressible portion. Here, toothbrush  170  has a two-piece compressible portion made up of rigid portion  172  and non-rigid portion  174 , which is attached to toothbrush handle  176 .  
         [0039]    Turning to FIG. 8, a fourth embodiment is shown. Again, an electric toothbrush handle  200  contains a compressible portion  202 . As in the preferred embodiment, magnet  204  is located beneath the compressible portion  202 . Here however, the switch plates have been replaced with a Hall effect sensor  206 . Application of force (F) to compressible portion  202  causes the distance between the magnet  204  and the Hall effect sensor  206  to decrease. When this distance is small enough, current flows through the Hall effect sensor  206  and the motor is engaged.  
         [0040]    [0040]FIG. 9 shows a fifth embodiment of the present invention. Electric toothbrush handle  220  contains compressible portion  222 . Below the compressible portion  222  are two contact plates  224  and  226 . Application of force (F) to compressible portion  222  causes the two contact plates to electrically connect, thereby completing an electric circuit and engaging the toothbrush motor.  
         [0041]    Referring to FIG. 10, an electric toothbrush  240  is shown in accordance with a sixth embodiment of the invention. In this embodiment, the mere presence of the user&#39;s hand on the handle causes movement of the brush head. In this figure, sensors  242  are located on the toothbrush handle. Typically a capacitive sensor would be used in this embodiment to allow the presence of the user&#39;s hand to close a switch in the handle, thereby engaging the motor.  
         [0042]    An electric circuit for this embodiment is shown in FIG. 11. Here, switch  250  has two positions: “off”, in which the circuit is open and no current can flow from power source  252  to motor  254 , and “automatic”, in which control of motor  254  is transferred to switch  256 . While in the automatic mode, the presence of the user&#39;s hand on the toothbrush handle will engage tactile sensors  258 . This causes switch  256  to close, and allows current to flow to motor  254 .  
         [0043]    Finally, FIG. 12 shows a simple wiring schematic  300  of a circuit configuration applicable to any of the embodiments described above. The button (shown as  12  in FIG. 1), now actuates a switch that has three positions instead of two. Turning back to FIG. 12, this switch is shown as  302 . When switch  302  is in the “off” position, circuit  304  is open and there is no voltage across motor  306 . When switch  302  is in the “on” position, circuit  304  is closed and there is a continuous voltage across motor  306 . Finally, when switch  302  is in the “automatic” position, control of the motor  306  is transferred to circuit  308 . Switch  310  closes circuit  308  only upon application of a force (F) to switch  310 . Hence, when switch  302  is in the “automatic” position, current will flow from power source  312  to motor  306  only as long as a force (F) is applied to switch  310 . Removal of force (F) opens circuit  308 , thereby disengaging motor  306 .  
         [0044]    While these embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.