Hair clippers with electrically adjustable blades

[0001] This application is based upon provisional application Ser. No. 61/117,434 filed Nov. 24, 2008, which application is incorporated by reference herein. Applicant claims priority under 35 USC §119(e) therefrom.

[0002] The present invention relates to hair cutting.

[0003] Electrically operated hair clippers have been used for many years. Some of the commonly available models have a manual lever on the side to incrementally adjust the relative position between the stationary and the reciprocating blades in a blade set to adjust the minimum length of hair that is being clipped. Other prior art patents show infinite adjustability over a range. The prior art does not reveal motor-powered continuous adjustability of the blade set which affords the barber the ability to perform the adjustment even during the clipping activity by simply activating a switch.

[0004] It is therefore an object of the present invention to provide a hair clippers device with infinitely variable blade distances from the scalp of the patron.

[0005] Other objects which become apparent from the following description of the present invention.

[0006] The hair clippers of this invention use a self-contained motor-driven adjustment mechanism to adjust the relative position of the stationary and reciprocating blades of a common type of blade set. Two momentary switches operable by the thumb of the hand holding the clipper afford a barber total automatic adjustment with the clipper itself in an on or off condition. There is no need for two-handed fidgeting or selection of only a few discrete increments of length adjustment as with the commonly available models. Since the small gear motors used for the adjustment are brush type or brushless permanent magnet motors which are operated by direct current, the adjustment feature is most compatible with cordless clippers already using an on-board DC source in the form of a re-chargeable battery to drive the reciprocating blade. The invention will be described as a modification of a cordless clipper, although AC driven corded type clippers can also be modified with this feature by the addition of an on-board AC to DC power supply for the adjustment motor.

[0007] In the first embodiment, a modified blade set is used such that a gear rack is attached to the stationary blade. It is engaged with a worm gear pinion driven by a low speed gear motor through a reversible drive circuit. Either limit switches, limit sensors, or over-current sensors are used to disable the adjustment motor at either the long or short hair end limits. The motor then can only be driven in the opposite direction.

[0008] In the second embodiment, a conventional blade set is used. The modification is such that a motor-driven final gear replaces the manual handle thereby retaining the original mechanism (of any type) that is used to move the stationary blade relative to the reciprocating blade in the conventional blade set. A timing belt couples a rear mounted adjustment motor to a front side-mounted gear train coupled to the shaft of the blade shifting mechanism. Attached to the timing belt for linear back and forth excursions is a magnet with a pointer. The magnet is used to operate two normally closed magnetic reed switches placed at the opposite distal ends of the permissible excursion thereby serving the limit switch function. The pointer moves over a tri-colored linear scale viewable by the barber from the top of the hair clipper; this quickly indicates the hair length setting. A plastic housing cover over the adjustment motor at the back and over the timing belt and gear train at the side encloses the entire compact mechanism.

[0018] FIGS. 1 and 2 show two views of a conventional cordless electric hair clipper 1 with on/off switch 3, conventional blade set 2, and side manual incremental adjusting handle 4. The detents 5 engage handle 4 to set the minimum hair cutting length at one of the selections.

[0019] FIG. 3 shows the mechanism which uses gear motor 10 driving worm gear pinion 11 to perform an adjustment of stationary blade 14 relative to reciprocating blade 13 in blade set 12. A gear rack 15 subassembly is attached to blade 14 and engages pinion 11. Also shown in this view are limit switches 16 and 17 at the longest and shortest settings respectively. FIGS. 4 and 4A show clipper housing 20 with the adjustment feature. Conventional on/off switch 25 connected to clipper motor 24 (shown schematically as an encircled “M”) is at one side while momentary (or “tap”) switches 21 and 22 on the top surface are used to energize gearmotor 10 in a direction toward longer settings or shorter settings respectively. Gearmotor 10 is enclosed in descending housing 26, which descends below clipper housing 20. While FIGS. 3, 4 and 4A show a worm gear, it is anticipated that other gears may be used, such as rack and pinion gears or other gears known to those skilled in the art.

[0020] FIG. 5 is a wiring diagram for the first embodiment of FIGS. 3 and 4 wherein gearmotor 10 is a simple brush type permanent magnet type driven by a common “H-bridge” drive module 35. Battery 30 is used primarily to power clipper motor 24 through on/off switch 25. It is also used as the power source for the adjustment feature. Drive module 35 has two direction inputs for clockwise and counter-clockwise operation, an “ON” input, and power input and motor output connections as shown. In operation, if normally open switch 22 is pushed, a signal will flow through normally closed limit switch 17 energizing the ON input through isolation diode 36; motor 10 will be driven clockwise until either switch 22 is released or limit switch 17 is opened at the end of the excursion. Similarly, if switch 21 is pushed, counter-clockwise operation is achieved through limit switch 16 and isolation diode 37. Once a limit switch is opened, motor 10 can only be driven in the opposite direction until the open limit switch is again closed.

[0021] FIGS. 6 and 7 show top and side views of the second embodiment of motor-driven minimum hair length adjustable hair clippers. The same circuit shown in FIG. 5 is completely applicable to this embodiment as well. The same momentary (“tap”) switches 21 and 22 are used to control motor 10 which is now placed at the back end of hair clipper 40. Except for the addition of switches 21 and 22, the housing 41 and internal mechanism is identical to that of the prior art cordless clipper shown in FIGS. 1 and 2. In this embodiment, a conventional blade set 12 and internal blade adjusting mechanism is used. The feature of this embodiment couples through the shaft formerly engaged with a manual handle 4. This is shown at the center of output gear 51. In the top view of FIG. 6, housing cover 42 is a plastic shell used to enclose the feature mechanism. In FIG. 7, this cover 42 is removed to reveal the mechanism; the position is shown in dashed lines. On the top edge of cover 42 is a tri-colored strip 43 with green region 45 denoting the long settings, yellow region 46 denoting medium length settings, and red region 47 denoting short settings. This scale is meant to be read relative to the position of pointer assembly 44 which is attached to timing belt 55 transmitting power and torque from pulley 57 mounted on motor 10 to pulley 56 attached to the input gear of gear train 50.

[0022] Gear train 50 is used to adjust the torque at output gear 51 and to match the speed and torque of gear motor 10 and the desired indicating excursion of belt 55 so as to form an ergonomic range. Besides the pointer on top, pointer assembly 44 also carries a small powerful magnet to operate limit switches 16 and 17 which are now implemented as normally closed magnetic reed switches. On/off switch 25 fits between timing belt 55 and pokes through a side switch hole in housing cover 42. While FIGS. 6 and 7 show a particular embodiment for an exterior mounted embodiment, it is anticipated that other exterior mounted embodiments may be used, such as those known to those skilled in the art.

[0023] In the foregoing description, certain terms and visual depictions are used to illustrate the preferred embodiment. However, no unnecessary limitations are to be construed by the terms used or illustrations depicted, beyond what is shown in the prior art, since the terms and illustrations are exemplary only, and are not meant to limit the scope of the present invention.

[0024] It is further known that other modifications may be made to the present invention, without departing the scope of the invention, as noted in the appended Claims.