Note: Descriptions are shown in the official language in which they were submitted.
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Brief Description of the Prior Art
A variety of shears and clippers have been developed
for the purpose of cutting, thinning and trimming hair by
the use of reciprocating, toothed blades.
The more common form of trimmer is that of a re-
ciprocating head carrying a blade for reciprocation trans-
versely of the axis of the handle of the unit which not
only makes such units clumsy for self-grooming, but also
requires a specific articulation of the hand which is
completely different from the more natural, flowing hand-
motion typical of brushing and combing.
In addition, such barbers' clippers are limited
to relatively short cutting heads which must be applied in
many individual strokes or sweeps, in trimming or shaping,
while skillfully maintaining alignment of adjacent sweeps
to avoid gouging or excessively deep cuts. This difficulty
is evident from the attempts that have been made to provide
uniformly-articulating gauges for assuring a uniform
tapering of their cut adjacent the neckline of haircuts.
Also, such barbers' clippers have had a charac-
teristic buzz-and-clatter noise which is unpleasant, at
best, and even startling or fearsome in the case of small
children or animals.
Accordingly, in spite of their widespread use,
transverse-cutting barber shears have not been found to
be entirely satisfactory.
Alternate forms of shears or trimmers have been
tried, including the use of a comb and reciprocating blade
which are aligned substantially longitudinally of the
instrument and its handle. These have ranged from finger-
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operated units to powered types and are, in fact, more
convenient and facile in use because of the orientation of
their handles and working elements in a manner similar to
the orientation of combs and brushes.
However, these latter clippers or trimmers are
still prone to unintentional gouging of the hair or, al-
ternatively, provide excessively light cuts requiring
repeated strokes to achieve the desired effect.
If high motor and blade speeds are ~ed in such
units, the noise factor is a strong deterrent with regard to
self-grooming by untrained individuals. If low motor and
blade speeds are used, the motor-noise factor may be re-
duced, but the sickle-bar or mowing-machine noise of the
blade may remain, particularly if the blade is relatively
long.
More significant, in regard to the actual capa-
bility of such units, is the fact that different cutting
rates are needed in the performance of different stages
of cutting or shaping the hair. A substantial cutting
rate is desirable for tapering. A lesser cutting rate is
advantageous in thinning operations, while a minimum cutting
rate is most desirable for blending adjacent zones to pro-
vide a smooth, finally-shaped cut.
Where transverse reciprocating barber shears are
able to accommodate these differing requirements by the use
of several interchangeable cutting heads, the cutters of
longitudinal clippers are not so readily interchanged as
are the smaller, snap-on heads.
This is especially important if it is desired to
avoid complexity and to overcome the reluctance of unskilled
persons to employ powered clippers in self-grooming. The
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long blade and gu~rd assemhlies lnherent in longitudinally~
reciprocating clippers would add a distinct ;nconvenience
if it were attempted to provide multiple heads of differing
cutting rates.
In order to avoid the need for multiple cutting
heads or multiple units, i~ has been necessary to provide
a compromise in cutting rate which is advantageous in only
one step of the hair cutting operation and sacrifices
efficiency and quality of results in other cutting steps.
Additionally, prior reciprocating clippers or shears
have been prone to jamming of the cutting blades when they
encounter more than their drive power and blade sharpness
can cut through. The manipulation necessary to free the
shears from the jamming hair or trapped material can be
painful, in the case of hair clippers, or dangerous to the
user, in the case of heavier duty shears. Certain prior
shear units have included overload protection means to pro-
tect the electric motors of the unit. ~owever, means are
needed to release the "lock-up" in the drive train to free
the driven blade so that it can idle or travel to a non-
biting position with regard to the opposing or stationary
teeth and thereby facilitate release of the jammed material.
Therefore, prior shears and trimmers have not
been found to be entirely satisfactory.
Objects of the Inventîon
It is an object of the present inYention to provide
a cutting unit having a cutting blade reciprocable generally
parallel to the longitudinal axis of the unit.
The present diYisional specifically relates ~o
a blade assemhly for shears including a pair of blades each
having a spine and a cutting edge thereon, said cutting edges
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being positioned adjacent each other
in shearing relationship, said cutting edges being curved
along the length of the blade, at least one of said blades having
a generally longitudinal recess in the spine thereof adjacent the
other of said blades, at least one of said blades having a groove
therein in communication with said recess, a plurality of balls
spaced apart longitudinally from each other in rolling engagement
with a wall of said groove and with the opposite spine portion of
the opposite blade, retaining means for maintaining said
blades in shearing relationship.
Brief Description of the Drawings
These and other objects of the present invention,
as well as a better understanding thereof, may be derived from
the following descriptions and accompanying draw~ings, in which:
Figure 1 is a side elevation, partly in section, of
the preferred embodiment of the present invention as a hair
trimmer;
Figure 2 is a top view, partly in section, of the
unit of Figure l;
Figure 3 is a cross-sectional view taken on lines
3-3 of Figure l;
Figure 4a is a perspective view, partly cut away,
of a portion of the phaseable eccentric drive phased to
maximum eccentricity;
Figure 4b is a view similar to Figure 4a and showing
the drive phased to zero eccentricity;
Figure 5 is a cross-sectional view, on an enlarged
scale, of a portion of Figure 1 and taken on lines 5-5 thereof;
Figure 6 is an enlarged view of a portion of
Figure 2; and
Figure 7 is an explodedview showing the relationship
of the drive, control and blade assemblies of the preferred
shear.
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srief Description of the Preferrecl Embodiment
As shown in the drawings, the preferred form of
hair trimmer of the present invention includes a casing 1
having a handle 2 and an anterior, narrowed portion 3
having an elongated slot 4 in its lower region. The casing 1
is formed by molded, separable upper and lower halves 5 and
6, respectively, which are secured by integrally-molded,
snap catches 7 distributed about the periphery of the joining
skirts 8 and 9 of the respective halves. At 1~3 forward
wall 10, the lower half 6 carries an elongated catch
member 11 which engages the upper surface of the upper
half 5.
The narrowed portion of the lower half 6 includes
a removable portion 12 carrying the slot 4 and further
secured by integrally molded catches 13. Advantageously, a
variety of removable portions 12 may be supplied with
varying configurations of combs or rakes 12a for engagement
with the hair.
Internally, the casing includes an upright boss 14
integral with the lower half and mounting an L-shaped
bracket 15 by means of a main screw 16. The bracket 15
includes a rear flange 17 having an aperture 18 therein for
receiving the shaft 19 of a motor 20 which is suitably
mounted on the rear flange such as by screws 21.
Adjacent the main screw 16, the bracket carries
a riveted shaft 22 carrying a drive train 23, described more
fully hereinafter. A forward extension 24 of bracket 15
carries a transverse shaft 25 which mounts a lever 26
carrying a blade assembly 27, also discussed more fully
hereinafter.
819Z
In the portion of the casing surrounding the
motor 20, the lower half 6 carries a spring arm 28 for en-
gaging a pair of batteries 29 and 30 which engage contacts
31 and 32 on an insulator wall 33 mounted on the rear flange
17 of the main bracket by the motor-mounting screws 21.
The contact 22 includes a leaf portion 34 extended through
an aperture 35 in the wall 33 to form a switch contact 36.
If desired, power may be delivered to the motor
from an external source via a jack member 37, shown in
dot-dash lines, instead of the batteries.
Forward of the motor and the switch contact 36 r
the main bracket 15 has a top flange 38 which mounts a
riveted shaft 39 at a slight angle to the longitudinal
axis of the casing. The shaft 39 carries a rocker arm 40
suitably secured thereon for a rocking motion. The rocker
arm 40 includes a pair of downwardly extending fork arms 41
and 41' as well as a top arm 42 positioned to rock into
lifting engagement with the rearward end 43 of the blade
assembly lever 26. A spring 44 mounted on the forward
extension 24 of the main bracket 15 engages and exerts a
downward force on the rear portion of the blade assembly
lever 26 and, consequently, the top arm 42 of the rocker
arm 40.
The downward force of spring 44 biases the rocker
arm so that its fork arms 41 and 41' are rocked outwardly
toward the side wall 45 of the casing, as can best be seen
in Figure 3.
Adjacent the fork arms 41 and 41', the side wall
45 includes an aperture 46 mounting a round control button
47, coaxial with the shaft 22 mounting the drive train, for
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reciprocation toward and away from the fork arms 41, 41'
which it engages via a shoulder 48. The control button 47
has a central stepped bore therein including a larger bore
49 and a shaft bore 50. At the junction of the bores 49
and 50, the control button includes a splined section 51 of
the large bore, whose purpose will be explained more fully
hereinafter. The control button also includes a closing
cap 52.
The mounting shaft 22 of the drive train, opposite
and coaxial with the control button 47, carries a worm-
geared sleeve 53 rotatably secured thereon, such as by a
c-clip 54, and which meshes with a wormrdrive pinion gear 55
mounted on the motor shaft 19. The worm-geared sleeve
carries a first eccentric member 56 fixed thereon which
includes a main portion 57 having a cylindrical bore 58
thereon whose axis is offset from the axis of the shaft
22 and sleeve 53 a selected radial distance.
A second eccentric member 59 includes a cylindrical
portion closely but loosely fitted within the cylindrical
bore 58 of the first eccentric member. The cylindrical
portion 60 is axially pressed against a shoulder 61 of
the first member by a dished spring 62 seated in a groove
63 in the bore 58 of the first eccentric. The cylindrical
portion 60 of the second eccentric includes a peripheral
channel 64 which extends over 180 of its circumference
and which is engaged by a spring-loaded pin 65 mounted in
the wall of the main portion of the first eccentric. The
pressure with which the pin 65 bears against the cylindrical
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portion 60 may be adjusted by a set screw 67 bearing against
the coil spring 66. The combined frictional loading imposed
by the dished spring 62 and the pin spring 66 resist
relative rotation of the cylindrical portion 60 in the
accentric bore 58, while the pin 65 limits the extremes of
such relative rotation when the frictional loading is over-
come, as will be discussed more fully hereinafter with regard
to operation of the unit.
The second eccentric member 59 also includes a
shaft portion 68 which extends transversely of the casing
toward the control button 47 and extends through the shaft
bore 50 to terminate well within the large bore 49. In
the region of the splined section 52, when the botton is
fully outwardly extended by the fork arm 41, 41', the
shaft portion has a transverse bore 69 loosely carrying a
clutch pin 70 in full engagement with opposite spline
grooves of the button.
The shaft portion 68 is radially offset or
eccentric with respect to its cylindrical portion 60, an
amount equal to that of the eccentricity of the main portion
and bore of the first eccentric 56. The peripheral channel
64 is to be located on the peripheral surface of the cylin-
drical portion 60 of the second eccentric so that it will
permit phasing of the two eccentric throws from maximum,
as in Figure 4a, to zero as in Figure 4b. The maximum
eccentric path of the shaft portion 68 is to be accommodated
by sufficient diameter in the shaft bore 50 to prevent
interference of the two.
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9z
Intermediate the cylindrical portion and the
botton, the shaft 68 engages a crank arm 71 positioned by
a C-clip and having a pin 71' which engages a movable toothed
blade 72 of the blade assembly 27.
The blade assembly includes a stationary toothed
blade 73 fixed on the lever 26. The blades 72 and 73 have
closely-associated, curvate toothed cutting edges 74 and
75, respectively, and curved spines 76 and 77. The spines
76 and 77 have curved grooves 78 and 79, on their adjacent
~aces, with a plurality of ball bearings 80 longitudinally
spaced in the channel formed by the grooves. The longi-
tudinal spacing of the balls 80 is fixed by a thin retainer
81 having individual apertures 82 for loosely receiving the
balls without interference therewith or with the surfaces
of the blades.
The blades are retained against separation by an
elongated assembly yoke 83 of spring material which spans
the spines of the blades and includes longitudinally spaced,
opposed sets of bearing pads 84. The spring yokes included
U-shaped, spring-clip guides 85 and 86 which engage both sides
of the forward extension 24 of the main bracket 15 along
forward and rearward guide edges 87 and 88, respectively, on
the extension 24. The guide edges 87 and 88 are preferably
equidistant with regard to the pin 89 fixing the stationary
blade on the lever 26 and are slightly curved to prevent
binding.
The electrical connections between the batteries
and the motor 20 are conventional and have not been detailed
in order to avoid complication of the drawings. However,
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a leaf contact 90 is included and is mounted on the fork
arm 41' of the rocker arm 40 to form a switch with the
adjacent switch contact 36. The leaf contact is positioned
to engage the contact 36 and close the motor circuit after
the botton has been depressed sufficiently to disengage the
spline section 51 from the clutch pin 70 in the large bore
49 of the botton.
Operation of the Preferred Embodiment
In operation of the preferred form of hair clipper
of the present invention, with the batteries or power source
installed, depression of the control button 47 closes the
switch contact 90 and 36 to energize the motor 20. The
pinion 55 drives the geared sleeve 53, the first eccentric
member 56 and the second eccentric member 59. If the first
and second eccentric members are phased as shown in Figure
4a to a maximum throw, the shaft 68 delivers a maximum re-
ciprocation to the crank arm 71 and a maximum length of stroke
to the movable blade 72.
Simultaneously with the actuation of the s~itch,
rocking of the rocker arm 40 by abutment of the fork arms
41, 41' with the shoulder 48 of the button exerts a lifting
pressure via the top arm against the rear end 43 of the
lever 26, thereby overcoming the bias of the spring 44
and causing the blade assembly to be extended through the
slot 4 into cutting position adjacent the hair engaging
portion of the removable member 12. The hair clipper may
then be used in much the same manner as a conventional comb,
with the curvate cutting edges of the blades generally
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eonforming to the contour of the head and prevention tan-
gential or chordal cutting as might occur with straight
cutting edges.
When it is desired to change the stroke of the
cutting blade assembly, the control button is released to
break the circuit to the motor and, simultaneously, to
retract the blade assembly under the bias of the spring 44.
With the button thus extended fully outwardly of the casing,
the clutch pin 70 is thus returned to its clutching engagement
with the splined seetion 51 so that the control button is in
positive, rotational engagement with the shaft portion 68 of
the second eccentric 59. Rotation of the button, within the
limits imposed by the peripheral channel 64 and spring
loaded pin 65, rephase the eceentricity of the first and
second eccentrie members to a desired loeation between the
maximum shown in Figure 4a and a lesser eecentricity
approaching the zero-phase shown in Figure 4b. Since the
motor is not energized, it acts as a brake on the first
eccentric, via the engagement of its pinion gear with the
geared sleeve, so that the rotation of the button may be
effective in overcoming the friction of the dished spring 62
and the spring loaded pin 65 to rephase the aecentries.
Thereafter, when the button is again depressed, the elutch
formed by the splined seetion 51 and eluteh pin 70 is
disengaged prior to elosing of the switch contaets 36
and 90 and the eeeentries are held in a selected phase under
the frictional load imposed by the dished spring 62 and
spring loaded pin 65. With the button thus depressed, there
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- ~is no interference between the clutch pin 70 and the large
bore 49 of the button, since the clutch pin is freely
slidable in the transverse bore 69 of the shaft portion and
simply reciprocates within that bore to accommodate the
eccentric motion between the shaft portion 68 and the large
bore 49 of the button.
! If a jam occurs at the shearing blades, the
present invention provides a peculiarly advantageous and
safe overload release. First, the jammed blade resists
further travel, while the motor continues to supply power to
the drive. ~he dished spring 62 and the spring loaded pin
65, under these circumstances, are unable to maintain the
selected phase relationship between the tto eccentric
members and thus permit them to rotate with respect to each
other until their eccentrics cancel each other, or repilase
.sufficiently to relieve the reciprocating pressure, if the
motor power is cut-off sufficiently quic~ly. Release of the
jam is easily accomplished by means of rotation of the
~phasing clutch until the biting or shearing pressure between
the shearing teeth is released, whereupon the jamr,inq
material is readily freed without pulling or .earing and
without dangerous manipulation bv unprotec.ed fingers. The
retractable blade of the preferred hair clipper supplements
this jam-release ability of the present invention bv pro-
viding a retracting force tending to separate the blade andthe jamming materlal transversely t~ith re~ard to the line of
reciprocation of the blade and, therefore, out from between
the teeth as soon as the shearing pressure is relieved.
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In the preferred embodiment of the present inver.tio~
as a hair clipper, the relatively lor.~, arcuate cutting
assembly and its longitudinal aiignment with the handle
portion of the casing not only provides for an e~tremely
convenient natural hand motion quite similar to the normal
combing motion, but also permits the unit to be used as a
comb intermediate actual cutting strokes, ~articularly since
the cuttin~ assembly is retracted within the housin~7 ~hen
the control button ls released. In this confi~uration, the
comb element mounted on the removable portion of the lower
housing may be used to smooth and realign a fresh cut, I;ith-
out the necessity of using a separate comb for that purpose.
As soon as the smoothing has been effected~ it is simply a
matter of again pressins the control button to resume the
;cutting operation. This capabilit~ can be of particular
advantage where the comb element of the removable portion
of the housins is to be used as a depth gauge for a trimming
operation such as that which is necessary ~lith beards.
Thcrefore, it is apparent that the present
invention has achieved its objectives and provides a par-
ticularl~ advantageous shear for trimming and grooming hair.
Furthermore, it is a?parent that the presert in~ention
;provides distinctly advantageous advances in s~fety and
ease of operation which may be employed with reci"rocating
cutting units other than hair clippers alone.
Therefore, various changes may be made in the
details of the invention as it has been disclosed without
sacrificing the advalltages ther20f or departing from the
scope of the apl)endcd clc~ims.
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