Abstract:
A hair clipper or trimmer including a controller and a pivot motor operable to control a reciprocating blade at a speed greater than 3,600 blade strokes per minute.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     Hand-held electrical devices, such as hair trimmers and clippers, typically include a motor. Hair trimmers and clippers can include a magnetic motor or a pivot motor. A magnetic motor generally operates (in the United States) with alternating current at 60 Hz (e.g., 60 cycles per second), and causes a blade to move 120 blade strokes per second. The magnetic motor generally provides 7,200 blade strokes per minute.  
         [0002]     A pivot motor generally operates (in the United States) with alternating current at 60 Hz, and causes a blade to move 60 blade strokes per second. The pivot motor generally provides 3,600 blade strokes per minute.  
       SUMMARY  
       [0003]     It would be desirable to have a hair clipper including a pivot motor that can operate at the same speed as a hair clipper including a magnetic motor.  
         [0004]     In one embodiment, the invention includes a hair clipper comprising a cutting blade, a pivot motor coupled to the cutting blade, and a controller operable to controllably provide electric power to the pivot motor to move the cutting blade at a speed greater than 3,600 blade strokes per minute.  
         [0005]     In another embodiment, the invention includes a controller for a pivot motor in a hair clipper. The controller comprises a power supply circuit operable to convert an alternating current (AC) signal to a direct current (DC) signal, a drive circuit operable to receive the DC signal and to generate a plurality of DC pulses, and a bridge circuit coupled to the pivot motor, the bridge circuit operable to switch the DC pulses, transform the DC pulses to a variable frequency AC signal, and transmit the variable frequency AC signal to the pivot motor.  
         [0006]     In yet another embodiment, the invention includes a hand-held electrical device comprising a housing, a blade set coupled to the housing, the blade set including a stationary blade and a reciprocating blade, an actuator supported by the housing, the actuator driveably connected to the blade set, and a controller supported by the housing, the controller operable to convert an alternating current (AC) signal to a direct current (DC) signal, generate a plurality of DC pulses, and transform the DC pulses to a variable frequency AC signal that is transmitted to the actuator to move the reciprocating blade. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  illustrates a top view of a hair clipper or trimmer.  
         [0008]      FIG. 2  illustrates a top view of the hair clipper or trimmer of  FIG. 1  with a portion of a housing removed.  
         [0009]      FIG. 3  illustrates a top view of a pivot motor of the hair clipper or trimmer of  FIG. 1 , the pivot motor being in a first position.  
         [0010]      FIG. 4  illustrates a top view of a pivot motor of the hair clipper or trimmer of  FIG. 1 , the pivot motor being in a second position.  
         [0011]      FIG. 5  illustrates a top view of a pivot motor of the hair clipper or trimmer of  FIG. 1 , the pivot motor being in a third position.  
         [0012]      FIG. 6  illustrates a schematic diagram of a controller of the hair clipper or trimmer of  FIG. 1 .  
         [0013]      FIG. 7  illustrates a first construction of a schematic diagram of a power supply circuit of the controller of  FIG. 6 .  
         [0014]      FIG. 8  illustrates a second construction of a schematic diagram of a power supply circuit of the controller of  FIG. 6 .  
         [0015]      FIG. 9  illustrates a third construction of a schematic diagram of a power supply circuit of the controller of  FIG. 6 .  
         [0016]      FIG. 10  illustrates a first construction of a schematic diagram of a drive circuit of the controller of  FIG. 6 .  
         [0017]      FIG. 11  illustrates a second construction of a schematic diagram of a drive circuit of the controller of  FIG. 6 .  
         [0018]      FIG. 12  illustrates a third construction of a schematic diagram of a drive circuit of the controller of  FIG. 6 .  
         [0019]      FIG. 13  illustrates a first construction of a schematic diagram of an bridge circuit of the controller of  FIG. 6 .  
         [0020]      FIG. 14  illustrates a second construction of a schematic diagram of an bridge circuit of the controller of  FIG. 6 .  
         [0021]      FIG. 15  illustrates a second arrangement of the hair clipper or trimmer of  FIG. 1  with the controller of  FIG. 6 .  
         [0022]      FIG. 16  illustrates a third arrangement of the hair clipper or trimmer of  FIG. 1  with the controller of  FIG. 6 . 
     
    
     DETAILED DESCRIPTION  
       [0023]     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limited. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The terms “mounted,” “connected,” “supported,“and “coupled” are used broadly and encompass both direct and indirect mounting, connecting, supporting, and coupling. Further, “connected,” “supported,” and “coupled” are not restricted to physical or mechanical connections or couplings, and can include electrical connections or couplings, whether direct or indirect.  
         [0024]     In addition, it should be understood that embodiments of the invention include both hardware and electronic components or modules that, for purposes of discussion, may be illustrated and described as if the majority of the components were implemented solely in hardware. However, one of ordinary skill in the art, and based on a reading of this detailed description, would recognize that, in at least one embodiment, the electronic based aspects of the invention may be implemented in software. As such, it should be noted that a plurality of hardware and software based devices, as well as a plurality of different structural components may be utilized to implement the invention. Furthermore, and as described in subsequent paragraphs, the specific mechanical configurations illustrated in the drawings are intended to exemplify embodiments of the invention and that other alternative mechanical configurations are possible.  
         [0025]      FIG. 1  illustrates a hair trimmer or clipper  10  according to one embodiment of the present invention. The hair clipper  10  includes a hollow, elongated housing  14  having a cutting end  18 . The illustrated housing  14  can be constructed of an electrically insulating material, such as plastic, and can include a plurality of sections or parts which are connected together to define an inner cavity  22  (see  FIG. 2 ). The housing  14  can be constructed with other types of material and according to other designs, such as a design that includes more or fewer sections or parts than the number of sections or parts illustrated in the drawings.  
         [0026]     The housing  14  can support an electric motor (e.g., pivot motor or vibratory motor) or actuator  26  and a motor controller  30  electrically connected to the electric motor  26 . As illustrated in  FIGS. 2-5 , the electric motor  26  (shown as a pivot motor) is drivingly connected to a blade set  34 , which is supported by the housing  14  at the cutting end  18 . The blade set  34  includes a fixed blade  38  mounted on the housing  14  and a movable or reciprocating blade  42  biased against and moveable with respect to the fixed blade  38  by the electric motor  26 . The electric motor  26  is mounted in the inner cavity  22  and is drivingly connected to the blade set  38  by a drive mechanism  44 .  
         [0027]     The housing  14  can include a power switch  46  (see  FIG. 1 ) for activation of the motor controller  30  and the electric motor  26 . When the power switch  46  is activated, the motor controller  30  controllably transmits electric signals to the electric motor  26  to effect reciprocation of the movable blade  42  with respect to the fixed blade  38 . The switch  46  is configured to interrupt the flow of electric power from a power supply to the motor controller  30 . The electric power may include an alternating current (AC) power provided via a corded plug electrically coupled to a wall outlet and/or a direct current (DC) power provided by a battery (e.g., a rechargeable battery disposed in the cavity  22 ). The housing  14  can include a speed switch  48  (see  FIG. 1 ) that can adjust the speed of the electric motor  26  and the movable blade  42 .  
         [0028]      FIGS. 3-5  illustrate operation of the pivot motor  26  (also referred to as a pivot machine).  FIG. 3  illustrates a power stroke in that the movable blade  42  has moved to the right when the hair clipper  10  is oriented in the vertical direction.  FIG. 4  illustrates that the movable blade  42  has moved to a neutral position.  FIG. 5  illustrates another power stroke in that the movable blade  42  has moved to the left when the hair clipper  10  is oriented in the vertical direction. The positions of the movable blade  42  as shown in  FIGS. 3-5  illustrate one complete blade stroke of a pivot motor.  
         [0029]     As the hair clipper  10  is guided through a person&#39;s hair, the reciprocating motion of the blade set  34  cuts the person&#39;s hair. A number of suitable blades sets, motors, and driving arrangements are known. It should be appreciated that hair trimmers having other types of blade sets, motors, and/or driving arrangements would be suitable for use in combination with the present invention.  
         [0030]     Several of the circuit diagrams illustrated in some of the FIGs are discussed below with respect to a 120V AC input power source. It should be noted that the circuit diagrams can be adjusted and/or reconfigured to accommodate a 230/240V AC power source, such that the invention is not limited to the electric circuit diagrams illustrated in the FIGS. The description of the embodiments of the invention include various component values and/or component sources or brands that are provided as examples. It is noted that the embodiments of the invention are not limited to the specific component values provided, but rather the component values can be adjusted and/or reconfigured to accommodate any change within any of the electric circuits illustrated.  
         [0031]     The motor controller  30  can increase the speed of the electric motor  26  in the hair clipper  10  of the present invention to operate at 7,200 blade SPM. Other speeds, greater than or less than 7,200 blade SPM, are also possible. Referring to  FIG. 6 , the motor controller  30  can include a power supply circuit  50 , a drive circuit  54 , and a bridge circuit  58 . The bridge circuit  58  is operable to transmit electric signals to the electric motor  26  for operation of the movable blade  42 .  
         [0032]     The power supply circuit  50  can provide a DC source to the drive circuit  54  and the bridge circuit  58 .  FIG. 7  illustrates one construction of the power supply circuit  50 . For the construction shown in  FIG. 7 , the power supply circuit  50 A includes an input terminal  62  that receives a 120V AC electric signal. The power supply circuit  50 A includes a time delay fuse  66  (e.g., 0.5 A), an inrush limiting resistor  70  (e.g., 24 ohm), a diode bridge rectifier  74  (e.g., IN4007 type) operable to provide a rectified output signal (e.g., DC signal), a resistor  78  (e.g., 4.4 Kohm) operable to limit the current that is provided to a zener diode shunt regulator  82  (e.g., 15V), which provides a low voltage input to the drive circuit  54 . The power supply circuit  50 A also includes a filter capacitor  86  (e.g., 470 μF) operable to store the rectified signal, a blocking diode  90  (e.g., IN4007 type), and a filter capacitor  94  (e.g., 10 μF) that provides a DC input signal to the bridge circuit  58 .  
         [0033]      FIG. 8  schematically illustrates another construction of the power supply circuit  50 . For the construction shown in  FIG. 8 , the power supply circuit  50 B includes an input terminal  98  that receives a 120V AC electric signal, a time delay fuse  102  (e.g., 0.5 A), an inrush limiting resistor  106  (e.g., 24 ohm), and a capacitor  110  (e.g., 1.2 μF) operable to limit the current to a zener diode shunt regulator  114  (e.g., 15V), which provides a low voltage input to the drive circuit  54 . The power supply circuit  50 B also includes a discharge resistor  118  (e.g. IN4007 type) positioned in a parallel path with the capacitor  110 , rectifier diodes  118  and  122  (e.g., IN4007 type) operable to provide a rectified output signal (e.g., DC signal) to the drive circuit  54 , and a filter capacitor  126  (e.g., 470 μF) operable to store the rectified signal. The power supply circuit  50 B further includes a rectifier diode  130  (e.g., IN4007 type), a filter capacitor  134  (e.g., 10 μF), and a discharge resistor  138  (e.g., 470 Kohm) that provides a DC input signal to the bridge circuit  58 .  
         [0034]      FIG. 9  schematically illustrates still another construction of the power supply circuit  50 . For the construction shown in  FIG. 9 , the power supply circuit  50 B includes a battery  142  operable to provide a DC input signal to the drive circuit  54  and the bridge circuit  58 . The power supply circuit  50  can be modified as needed to accommodate alkaline, NiCd, or NiMH batteries as the power source for the motor  26  and the motor controller  30 . The battery voltage can be in the range of about  5  volts to about  12  volts, but any voltage can be used as long as the electronics are stable and the motor power is adequate.  
         [0035]     The drive circuit  54  illustrated in  FIG. 6  can be a pulse width modulator that can provide two square wave pulse trains (A and B) to the bridge circuit  58 . The two pulse trains are out of phase with each other and have an amplitude close to the supply voltage (+12 VDC or +15 VDC). Even though the pulses A and B are out of phase, they share a small period of time when no pulses occur on either A or B. This ensures that the bridge circuit  58  is not destroyed as when opposite phases are turned on at the same time. The frequency applied by the drive circuit  54  to the bridge circuit  58  can be any frequency, but is preferably in the range of about 100 Hz to about 120 Hz.  
         [0036]      FIG. 10  schematically illustrates one construction of the drive circuit  54 . For the construction shown in  FIG. 10 , the drive circuit  54 A includes a pulse width modulator chip  146  (e.g., UC3525A type), pulse width set resistors  150  (e.g., 3 Kohm) and  154  (e.g., 1.5 Kohm), input impedance resistor  158  (e.g., 10 Kohm), and current limit resistor  162  (e.g., 5.1 Kohm). The drive circuit  54 A also includes an output frequency adjustable potentiometer  166  (e.g., 250 Kohm) and an output frequency set capacitor  170  (e.g., 0.1 μF) positioned in a parallel path with the output frequency adjustable potentiometer  166 . The arrangement of the output frequency adjustable potentiometer  166  and the output frequency set capacitor  170  generate an RC time constant that controls the frequency and, therefore, the speed of the electric motor  26 . The output power can be adjusted by modifying the width of the output pulses using a pulse width adjustable potentiometer  174  (e.g., 10 Kohm). Output power may also be fixed. The drive circuit  54 A further includes noise shunt capacitors  178  (e.g., 0.01 μF),  182  (e.g., 0.1 μF) and  186  (e.g., 0.1 μF), a current pulse capacitor  190  (e.g., 100 μF), and a “soft-start” capacitor  194  (e.g., 4.7 μF). A soft-start feature “slowly” increases the speed of the electric motor  26 , thus avoiding an abrupt change on the load. The drive circuit  54 A also includes a switch  198  (e.g., SPST type) (e.g., power switch  46 ) that provides power to the drive circuit  54 A.  
         [0037]      FIG. 11  schematically illustrates another construction of the drive circuit  54 . For the construction shown in  FIG. 11 , the drive circuit  54 B includes a microcontroller  202  programmed as a pulse width modulator that is operable to output the two pulse trains from its I/O pins. The microcontroller  202  can also be programmed to sense various analog voltages on its I/O pins to keep power constant or respond to line voltage variations. The drive circuit  54 B also includes pulse width limit resistors  206  and  210 , frequency limit resistors  214  and  218 , current limit resistor  222  (e.g.,  100  Kohm), and a frequency adjustable potentiometer  226  that controls the frequency and, therefore, the speed of the electric motor  26 . The output power can be adjusted by modifying the width of the output pulses using a pulse width adjustable potentiometer  230 . Output power may also be fixed. The drive circuit  54 B further includes a noise shunt capacitor  234  (e.g., 0.1 μF) and a switch  238  (e.g., SPST type) (e.g., power switch  46 ) that provides power to the drive circuit  54 B.  
         [0038]      FIG. 12  schematically illustrates still another construction of the drive circuit  54 . For the construction illustrated in  FIG. 12 , the drive circuit  54 C includes oscillator transistors  242  (e.g., 2N3904 type) and  246  (e.g., 2N3904 type) that form an astable multivibrator that outputs two pulse trains as shown. It is noted that various configurations of transistors can form an astable multivibrator and that the invention is not limited to the specific configuration of the transistors illustrated. The drive circuit  54 C also includes current limit resistors  250  (e.g., 15 Kohm) and  254  (e.g., 15 Kohm), frequency set resistors  258  (e.g., 150 Kohm) and  262  (e.g., 150 Kohm), and a frequency adjustable potentiometer  266  (e.g., 10 Kohm) that controls the frequency and, therefore, the speed of the electric motor  26 . The drive circuit  54 C further includes frequency set capacitors  270  (e.g., 0.027 μF) and  274  (e.g., 0.027 μF), steering/switching diodes  278  (e.g., IN4148 type) and  282  (e.g., IN4148 type), and a switch  286  (e.g., SPST type) (e.g., power switch  46 ) that provides power to the drive circuit  54 C.  
         [0039]     The drive circuit  54  and the bridge circuit  58  illustrated in  FIG. 6  form an inverter. The bridge circuit  58  illustrated in  FIG. 6  uses the control pulses produced by the drive circuit  54  to switch electrical energy (power) into the electric motor  26 . The energy is usually rectified and filtered line voltage, but can also be low voltage (such as from batteries) for a portable hair clipper  10 . The power switches are usually MOSFET transistors, but can be suitable transistors of any type, such as IGBT (insulated gate bipolar transistors) or BJT (bipolar junction transistors).  
         [0040]      FIG. 13  schematically illustrates one construction of the bridge circuit  58 . For the construction shown in  FIG. 13 , the bridge circuit  58 A includes an “H bridge” output MOSFET transistors  290  (e.g., IRFU-220N),  294  (e.g., IRFU-220N),  298  (e.g., IRFU-220N), and  302  (e.g., IRFU-220N) operable to switch the DC pulses through the motor coil first in one direction, stop, and then switch the DC pulses in a second direction. The bridge circuit  58 A also includes constant load resistors  306  (e.g., 47 Kohm) and  310  (e.g., 47 Kohm), bias resistors  314  (e.g., 68 Kohm) and  318  (e.g., 68 Kohm), gate drive resistors  322  (e.g., 22 Kohm),  326  (e.g., 22 Kohm),  330  (e.g., 100 Kohm), and  334  (e.g., 100 Kohm), a current feedback resistor  338  (e.g., 1-10 ohms), voltage pump capacitors  342  (e.g., 2.2 μF) and  346  (e.g., 2.2 μF), and voltage steering diodes  350  (e.g., IN4007 type) and  354  (e.g., IN4007 type). The bridge circuit  58 A further includes gate turn-off diodes  358  (e.g., IN4148 type),  362  (e.g., IN4148 type),  366  (e.g., IN4148 type), and  370  (e.g., IN4148 type) and MOSFET turn-off transistors  374  (e.g., MPSA42 type) and  378  (e.g., MPSA42 type).  
         [0041]     In operation, if either of the input DC pulses A or B is in a high state, the output MOSFET transistors  298  or  302  turn on through gate drive resistors  330  or  334 , respectively. At the same time, the turn off transistors  374  and  378  cause the output MOSFET transistors  290  and  294  to turn off, respectively. The output MOSFET transistors  298  and  302  are discharged through gate turn off diodes  366  and  370 , respectively, when either of the input DC pulses A or B is in a low state. At the same time, turn-off transistors  374  or  378  are not forward biased and the charge contained on the voltage pump capacitors  342  and  346  causes the output MOSFET transistors  290  and  294  to turn on through gate drive resistors  322  and  326 , respectively. The voltage steering diodes  350  and  354  charge the voltage pump capacitors  342  and  346 , respectively, with a positive voltage referenced to the voltage being applied to the motor  26 . The gate turn off diodes  358  and  362  ensure a rapid turn off of the output MOSFET transistors  290  and  294 , respectively. The current feedback resistor  338  allows current drawn by the motor  26  to be changed to a voltage level, which can be used for features such as overload protection or constant power.  
         [0042]     The bridge circuit  58 A illustrates the electrical location of the motor  26  and an associated motor coil  382 . The motor coil  382  is single-ended, which allows for easy motor bobbin winding. A single-ended motor coil construction also allows the H-bridge output stage to use lower voltage MOSFETs with low “on-resistance.” The lower on resistance creates a cooler operation in the bridge circuit  58 A.  
         [0043]      FIG. 14  schematically illustrates another construction of the bridge circuit  58 . For the construction shown in  FIG. 14 , the bridge circuit  58 B includes constant load resistors  386  (e.g., 47 Kohm) and  390  (e.g., 47 Kohm), gate drive resistors  394  (e.g., 100 Kohm) and  398  (e.g., 100 Kohm), and gate turn-off diodes  402  (e.g., IN4148 type) and  406  (e.g., IN4148 type). The bridge circuit  58 B also includes MOSFET output transistors  410  (e.g., IRFU320 type) and  414  (e.g., IRFU320 type), which turn on through the gate drive resistors  394  and  398  when either the A or B input pulse is in a high state. The MOSFET output transistors  410  and  414  turn off and are discharged through the gate turn-off diodes  402  and  406  when the A or B input pulse is in a low state. A resistor connected to the source of each of the MOSFET output transistors  410  and  414  can be used for current feedback as described above with respect to  FIG. 13 .  
         [0044]     The bridge circuit  58 B illustrates the electrical location of the motor  26  and an associated motor coil  418 . The motor coil  418  is center-tapped, which allows for a more simplified bridge circuit  58 B.  
         [0045]     The embodiments of the invention described above illustrate the motor controller  30  as being incorporated in the housing  14  of the hair clipper  10 . It should also be noted that the motor controller  30  can be housed in a separate enclosure  422  that can be incorporated within an AC line cord as illustrated in  FIG. 15  or the motor controller  30  can be incorporated in a self-contained wall plug  426  as illustrated in  FIG. 16 .  
         [0046]     Various features and advantages of the invention are set forth in the following claims.