Patent Application
20110289777
The field of the invention relates generally to electric hand-held hair cutting appliances, such as those used for hair trimming, clipping and shaving, and particularly to a blade clamping device for such electric hand-held hair cutting appliances.
Electric hand-held hair cutting appliances come in a number of different types depending on the intended use of the appliance, such as for trimming facial or body hair, clipping the hair on one's head or on a pet, or for shaving facial or body hair. Such hair cutting appliances typically have at least one stationary blade and at least one reciprocating blade. Each of the blades includes a plurality of shearing teeth defining a cutting edge margin. The shearing teeth of the reciprocating blade overlie, in face-to-face contact with, the shearing teeth of the stationary blade. The reciprocating blade is operatively connected to an eccentric drive assembly such that rotation of the drive assembly linearly reciprocates the reciprocating blade relative to the stationary blade so that the shearing teeth of the reciprocating blade reciprocate across the shearing teeth of the stationary blade, thereby producing shearing action between the reciprocating blade teeth and the stationary blade teeth.
It is common for the reciprocating blade to be held in sliding engagement with the stationary blade by a blade mounting device that typically includes a spring member that biases the blades together. Known conventional blade mounting devices, however, have several disadvantages. For example, one known blade mounting device includes a double torsion spring for such a purpose. The spring has a pair of arms that hold the reciprocating blade against the stationary blade. The coil portions of the spring are fixed relative to the stationary blade, so during reciprocating movement of the reciprocating blade, the spring arms cause the reciprocating blade to move along an arcuate path, rather than a desired linear path, relative to the stationary blade.
In another known example, the blade mounting device includes a double torsion spring pressing a linear guide component against the reciprocating blade for guiding the reciprocating blade along a linear path across the stationary blade. The linear guide component is connected to a base of the blade mounting device by a pair of resiliently flexible (i.e., elastic) arms. The arms are constructed to have a low modulus of elasticity so that a large majority of the force exerted by the spring is applied to the linear guide component, as opposed to the arms. However, because the arms have such a low modulus of elasticity, the arms tend to buckle during heavy loading, leading to the reciprocating blade moving rearward on the stationary blade. This rearward movement displaces the shearing teeth of the reciprocating blade relative to the shearing teeth of the stationary blade, which can negatively affect the quality of the cut by the hair cutting appliance.
In one aspect, a hand-held hair cutting appliance generally comprises a first blade including a plurality of shearing teeth defining a first cutting edge margin, and a second blade including a plurality of shearing teeth defining a second cutting edge margin. The second cutting edge margin is in sliding engagement with the first cutting edge margin. A drive assembly of the appliance is operatively connected to the second cutting blade. The drive assembly is operable to impart reciprocating movement of the second blade relative to the first blade so that the shearing teeth of the second blade slide across the shearing teeth of the first blade. A blade clamping device of the appliance urges the second cutting edge margin in sliding engagement with the first cutting edge margin. The blade clamping device includes a clamping head configured for pivoting movement generally toward and generally away from the second blade about a pivot axis. The clamping head is resiliently biased generally toward the second blade about said pivot axis into sliding engagement with the second blade, whereby the second blade is slidable relative to the clamping head during said reciprocating movement of the second blade relative to the first blade.
In another aspect, a hand-held hair cutting appliance generally comprises a first blade having a cutting edge margin, and a second blade having a cutting edge margin overlying at least a portion of the cutting edge margin of the first blade. A drive assembly of the appliance is operatively connected to the second blade. The drive assembly is configured to impart reciprocating movement of the second blade relative to the first blade. A blade clamping device of the appliance holds the second blade in relation to the first blade. The blade clamping device includes a base, and a linear guide component engaging the second blade for guiding the second blade along a selected path during said reciprocating movement so that the cutting edge margin of the second blade moves in a substantially linear cutting path along the cutting edge margin of the first blade. At least one arm of the blade clamping device pivotally connects the linear guide component to the base to allow for movement of the linear guide component generally toward and generally away from the second cutting blade about a pivot axis. A spring member of the blade clamping device applies a load on the linear guide component in a direction generally toward the second cutting blade. The at least one arm has a bending stiffness sufficient to substantially resist bending of said at least one arm due to said load being applied to the linear guide component by the spring member.
In yet another aspect, a blade head assembly for a hand-held hair cutting appliance of the type including an electric drive assembly generally comprises a first blade including a plurality of shearing teeth defining a cutting edge margin, and a second blade including a plurality of shearing teeth defining a cutting edge margin. The cutting edge margin of the second blade is in sliding engagement with the cutting edge margin of the first blade and is configured for operative connection to the electric drive assembly of the hand-held hair cutting appliance to impart reciprocating movement of the second blade relative to the first blade. A blade clamping device of the blade head assembly urges the cutting edge margin of the second blade in said sliding engagement with the cutting edge margin of the first blade. The blade clamping device includes a clamping head operable for pivoting generally toward and generally away from the second blade about a pivot axis. The clamping head is resiliently biased generally toward the second cutting blade about said pivot axis into sliding engagement with the second blade, whereby the second blade is slidable relative to the clamping head during said reciprocating movement of the second blade relative to the first blade.
Corresponding reference characters indicate corresponding parts throughout the drawings.
Referring now to the drawings and in particular to
The housing 12, or a portion thereof, is suitably sized and shaped as a handle so that it is easily held in a user's hand. The illustrated housing 12 is elongate and is of two-piece construction including a base 20 and a cover 22 (see
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It is understood that the linear guide component may comprise any number of suitable rails 58 other than two. It is also understood that the linear guide component may have another suitable configuration other than rail(s) 58, and/or the reciprocating blade 42 may have another suitable configuration other than the groove 60. For example, the linear guide component may comprise one or more grooves (not shown) that receive one or more rails (not shown) associated with the reciprocating blade 42. Moreover, the groove 60 or other structure may be part of a separate component that is secured to the reciprocating blade 42. Other suitable configurations are within the scope of the present invention. It is also contemplated that a guide component which guides the reciprocating blade 42 along a path other than substantially linear (i.e., straight) may be used in lieu of the linear guiding component. It is further contemplated that the linear guide component or other guiding component may be omitted from the clamping head 52, such that the clamping head does not guide the reciprocating blade 42 along a path.
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For purposes of facilitating assembly of the blade head assembly 14, the clamping device 50 may include other suitable means of limiting the degree to which the clamping head 52 pivots generally toward and generally away from the reciprocating blade 42 about the pivot axis A. For example, the clamping device 50 may include one or more rigid posts or stops (not shown) extending outward from the base 54. The posts may be configured to contact the arms 56 of the blade clamping device 50 when the arms are pivoted to a selected angular position about the pivot axis A. Such posts would inhibit the arms 56, and thus the clamping head 52, from pivoting beyond the posts in a direction generally away from the reciprocating blade 42. The clamping device 50 may include other suitable means of limiting the degree to which the clamping head 52 pivots generally toward and generally away from the reciprocating blade 42 about the pivot axis A during assembly of the blade head assembly 14. Furthermore, the ribs 65 and the keyed portions 63a, and/or other means for limiting the pivoting movement of the clamping head 52 may be suitably omitted without departing from the scope of the present invention.
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With the tongue portion 69 of the spring member 66 held in its bending position by the hold down member 74, the arm portions 70 of the spring member engage the clamping head 52 and transmit the force of the spring member to the clamping head. Terminal end margins of the arm portions 70 are received in respective slots 76 in the clamping head 52 to locate the arm portions in desired positions on the linear guide component adjacent to the ends of the clamping head. The spring member 66 exerts a load on the clamping head 52 of a magnitude sufficient to hold or retain the linear guide component (e.g., the rails 58) in operative, sliding engagement with the reciprocating blade 42 (e.g., in sliding engagement in the groove 60) so that the cutting edge margin of the reciprocating blade 42 is held or retained in face-to-face, sliding engagement with the cutting edge margin of the stationary blade 40 and the reciprocating shearing teeth 46 move across the stationary shearing teeth 44 in a substantially linear cutting path during operation. For example, the load exerted on the clamping head 52 by the spring member 66 in accordance with the illustrated embodiment may be of a magnitude from about 0.44 pound-force to about 0.66 pound-force. It is understood, however, that the spring member 66 may exert suitable load outside this range without departing from the scope of the present invention. It is also understood that the suitable magnitude of the force exerted by the spring 66 may be dependent on the type of hair cutting appliance.
As mentioned above, the arms 56 of the blade clamping device 50 are preferably relatively stiff to inhibit buckling of the arms when the hair cutting appliance 10 is under a relative large load (i.e., when cutting thick hair or cutting hair relatively quickly). More specifically, in one embodiment the arms 56 have bending stiffnesses sufficient to resist bending of the arms due to the load being applied to the clamping head 52 by the spring member 66. In other embodiments, though, the arms 56 may have bending stiffnesses that are insufficient to resist bending of the arms due to the load applied to the clamping head 52 by the spring member 66.
When introducing elements of the present invention or preferred embodiments thereof, the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including”, and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
As various changes could be made in the above constructions and methods without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
