Clipper blade assembly

A clipper blade for use in a blade assembly of a hair clipper, the blade assembly having a fixed blade and a moving blade reciprocating relative to the fixed blade, the clipper blade includes a web portion having a first edge, and a second edge, a plurality of teeth on at least one of the first and second edges, at least one blade assembly engagement formation being located on the web portion closer to one of the first and second edges than the other of the edges, so that when a pair of blades each having the web portion and the at least one engagement formation are inserted into the blade assembly in reversed opposing relationship to each other, one blade of the pair being the fixed blade edge and having a plurality of teeth on the first edge, and the other blade of the pair being the moving blade and having a plurality of teeth on the second edge, the moving blade is laterally offset relative to the fixed blade.

RELATED APPLICATION 
The present application is related to co-pending application Ser. No. 
08/327,436 entitled "DETACHABLE PIVOTING CLIPPER BLADES" filed on Oct. 21, 
1994. 
BACKGROUND OF THE INVENTION 
The present invention relates to blade assemblies for electric hair 
clippers, and specifically to the construction and arrangement of blades 
in such assemblies. 
Conventionally available electric clippers include two main components: a 
combined handle and drive system, and a blade assembly which is frequently 
removable. The blade assembly includes a housing enclosing a fixed blade 
and a moving blade reciprocating relative to the fixed blade. In some 
applications, the blade assembly is intended to be disposable, such as 
when used in clipping patients' hair prior to surgery. Also included in 
the blade assembly is a cam follower or similar device generally disposed 
in the housing and configured for engagement with a drive member in the 
handle portion, which transmits the driving motion generated by the drive 
member to the moving blade. 
Conventional blade assemblies also include a spring or other biasing 
structure for biasing the moving blade against the fixed blade. Hair 
cutting takes place through the scissors action of the reciprocating 
action of the moving blade relative to the fixed blade. 
One common disadvantage of conventional clippers occurs through the 
separate construction of the fixed and moving blades. This occurs largely 
due to the fact that the construction of the tooth pattern and geometry of 
the fixed blade is often distinct from those of the moving blade. More 
specifically, the spacing, tip shape and angle of the teeth often vary 
between the fixed and moving blades. The presence of multiple blade parts 
adds to the burden on clipper manufacturers of maintaining inventory and 
keeping assembly workers supplied with parts on a timely basis. In 
addition, a greater disparity of component parts often results in a 
correspondingly more difficult assembly worker training task for the 
manufacturer. 
A further disadvantage of the conventional system of employing separate 
parts for the fixed and moving blades is that these blades are often 
produced one-at-a-time in progressive die tooling by stamping machines 
from rolled steel stock. The high cost of modifying or replacing existing 
stamping dies has tended to discourage change in this area. 
Thus, an object of the present invention is to provide improved fixed and 
stationary blade elements for use in a clipper blade assembly wherein the 
fixed and moving blades are provided as a substantially identical single 
unit which can either be used as a fixed blade or a moving blade. 
Another object of the present invention is to incorporate specific geometry 
of fixed and moving blades into a single blade part so that the desired 
cutting action and blade orientation of conventional clippers is 
maintained. 
Still another object of the present invention is to provide a blade 
assembly for use in an electric clipper wherein the fixed and stationary 
blades are made of substantially identical parts. 
SUMMARY OF THE INVENTION 
Accordingly, the above-listed objects are met or exceeded by the present 
blade construction for a clipper blade assembly, wherein a single web has 
both a fixed blade cutting edge and a moving blade cutting edge. The 
present blade unit may be positioned in the blade assembly housing as a 
fixed blade, and a second such unit may be positioned in the housing as 
the moving blade. The blade unit is specially configured to include the 
particular structural characteristics of both the fixed and moving blades. 
More specifically, the present invention provides a clipper blade for use 
in a blade assembly of a hair clipper, the blade assembly having a fixed 
blade and a moving blade reciprocating relative to the fixed blade. The 
present clipper blade includes a web portion having a first edge, and a 
second edge, and a plurality of teeth on at least one of the first and 
second edges. At least one blade assembly engagement formation is located 
on the web portion closer to one of the first and second edges than the 
other of the edges, so that when a pair of blades each having said web 
portion and said at least one engagement formation are inserted into the 
blade assembly in reversed opposing relationship to each other, one blade 
of the pair being the fixed blade edge and having a plurality of teeth on 
said first edge, and the other blade of the pair being the moving blade 
and having a plurality of teeth on said second edge, the moving blade is 
laterally offset relative to the fixed blade. In the preferred embodiment, 
the first cutting edge is configured for application as the fixed blade, 
the second cutting edge is configured for application as the moving blade, 
and the blades are substantially identical to each other. 
In another embodiment, a blade assembly is provided for use with a hair 
clipper including a handle with a drive end, a drive member extending from 
the drive end, and a first coupling formation disposed at the drive end. 
The blade assembly includes a housing having a second coupling formation 
configured for engaging the first coupling formation, with the second 
coupling formation being configured for accommodating the drive member. 
The housing also has a blade locating formation for locating a fixed blade 
thereon. Also included in the assembly are a pair of substantially 
identical cutting blades, each having a web portion having at least one of 
a first cutting edge and a second cutting edge, the first cutting edge 
being longer than the second cutting edge, and the first cutting edge 
being configured for application as the fixed blade, and the second 
cutting edge being configured for application as the moving blade. One of 
the blades serves as the fixed blade by employing the first cutting edge, 
and the other of the blades serves as the moving blade by employing the 
second cutting edge. 
In still another embodiment, a clipper blade is provided for use in a blade 
assembly of a hair clipper, the blade assembly having a fixed blade and a 
moving blade reciprocating relative to the fixed blade. The clipper blade 
includes a web portion having a first edge and a second edge, the second 
edge being longer than the first edge, a first plurality of teeth on the 
first edge, and a second plurality of teeth on the second edge. The web 
portion is vertically offset from at least one of the first and second 
edges. At least one blade guide slot and at least one blade locating slot 
are located in the web.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIGS. 1 and 4, an electric hair clipper of the type 
suitable for use with the present invention is generally designated 10, 
and includes a motorized handle portion 12 having a drive end 14, a 
recharge end 16 opposite the drive end, and a switch 18 located 
therebetween. More specifically, the handle portion 12 includes a housing 
20 preferably made of durable, impact-resistant, molded polymeric material 
as is known in the art. Enclosed by the housing 20 is a battery 22 (shown 
hidden), which in the preferred embodiment is rechargeable, however 
disposable batteries or the use of A.C. power are also contemplated. 
Terminals 24 for engaging a recharging stand (not shown) are located at 
the recharge end 16. 
Connected to the battery 22 in a known manner is an electric motor 26 
(shown hidden) which is secured within the housing 20, is electrically 
connected to the switch 18, and which has a drive shaft or armature 27 
(best seen in FIG. 4) secured to an offset cam eccentric 28 (best seen in 
FIG. 4). The arrangement and operation of the motor 26, the battery 22, 
and the cam eccentric 28 are similar to components which are well known in 
the art and are described in detail in commonly assigned U.S. Pat. No. 
5,068,966, which is incorporated by reference herein. 
At the drive end 14 is provided a first coupler formation 30 which is 
frusto-spherical or bowl-like in shape and defines a central cavity 32 
(best seen in FIG. 4) into which projects the cam eccentric 28 and a lobe 
or spherically shaped drive actuator member 34. The actuator member 34 is 
preferably fixed upon the cam eccentric 28. In fact, the actuator member 
34 and the cam eccentric 28 may be machined as a single piece, and it is 
contemplated that any equivalent method of attaching a ball to orbit about 
the centerline of a motor shaft may be suitably employed. 
Referring now to FIGS. 1-4, included with the clipper 10 is a blade 
assembly, generally designated 40, which is made up of a blade assembly 
housing 42 preferably having a first housing portion 44 and a second 
housing portion 46. The first housing portion 44 includes a shroud or 
swivel formation 48 which is also generally frusto-spherical or bowl 
shaped and defines a central recess 50. The formation 48 defines a socket 
dimensioned to accommodate the first coupler formation 30, is preferably 
dimensioned to encompass and accommodate the first coupler formation in a 
ball-and-socket connection, and as such is also referred to as a second 
coupler formation. Upon engagement of the first and second coupler 
formations 30, 48, the blade assembly 40 is rotatable a full 360.degree. 
about the first coupler formation 30, and is also preferably pivotable 
relative to the drive end 14, in the range of 30.degree. in the embodiment 
described. Either of the first and second coupler formations 30,48 may be 
located on either the blade assembly 40 or the drive end 14. 
In the preferred embodiment, the swivel formation 48 is provided with a 
biasing force with which it grips the first coupler formation 30, and 
which may be overcome when the blade assembly 40 is disengaged from the 
coupler formation 30 of the handle portion 12. Such biasing force is 
provided by at least one and preferably four notches 52 defining the 
swivel formation 48 into multiple spring-biased tabs 54. To facilitate 
both the pivoting action of the swivel formation 48 relative to the 
coupler formation 30, the formation 48 is preferably made of a relatively 
more resilient plastic material, or is constructed to have a lower spring 
rate, while the formation 30 is more rigid either through material 
selection or component construction as is known in the art. It is also 
contemplated that the relative flexibility of the formations 48 and 30 may 
be reversed. 
At a base end 56 of the swivel formation 48 is defined an opening 58 which 
is in communication with an interior housing chamber 60 (best seen in FIG. 
3). Opposite the base end 56, the swivel formation includes an annular rim 
62 and preferably at least one radially extending release tab 64 
integrally joined to said rim. In the preferred embodiment, the release 
tab 64 is constructed and arranged to be large enough to be engaged by an 
operator's thumb. A pushing force exerted in the direction indicated by an 
arrow 66 (best seen in FIG. 1) will disengage the blade assembly 40 from 
the handle portion 12. An added feature is that the arrow 66 is integrally 
molded onto the swivel formation 48 to serve as a permanent indicator. 
Aside from the swivel formation 48, the first housing portion 44 includes 
an upper surface 68 to which the swivel formation is attached, and a 
depending skirt 70. 
The second housing portion 46 has a substantially planar floor 72 with an 
upstanding peripheral wall 74 on three sides, 76, 78 and 80. The 
peripheral wall 74 is constructed and arranged to be fixed to opposing 
portions of the depending skirt 70 using chemical adhesive, ultrasonic or 
RF welding, or other suitable attachment technologies. A feature of the 
present blade assembly 40 is that the floor 72 has a lower outer surface 
with a significant surface area with which to contact the subject's skin 
and/or to contact a hair comb, depending on the application. In this 
manner, guidance is provided to the operator for hair clipping purposes. 
Referring now to FIG. 2, the floor 72 is generally inclined toward an open 
side 82 and is provided with a blade locating lug 84 which is preferably 
integrally formed with the floor 72. The lug 84 is preferably elongate in 
shape and has a longitudinal axis which is generally parallel to the sides 
76 and 80. Further, the lug 84 has a height preferably designed to be 
slightly taller than the cross-sectional thickness of a fixed blade 86 to 
maintain the blade in a fixed position on the floor 72. It is also 
contemplated that the lug 84 may be slightly shorter than the blade 
thickness, as long as the blade 86 is prevented from moving. 
Adjacent each side of the lug 84 is disposed a blade guide boss 88 which is 
integrally formed or otherwise secured to the floor 72 for guiding a 
reciprocating or moving blade 90 relative to the fixed blade 86. The blade 
guide bosses 88 also each have a broad-shaped base 89 which aids in 
supporting and securing the fixed blade 86 in position on the floor 72. In 
the preferred embodiment, the blade guide bosses 88 are each preferably 
oriented at a 90.degree. angle to the blade locating lug 84, and 
preferably have a relatively equal or greater height for engaging the 
moving blade 90 as will be described below. It is also preferred that the 
floor 72 be provided with a support rib 91 which projects vertically from 
the floor to support an underside of the fixed blade 86. 
In addition to the first and second housing portions 44, 46, and the fixed 
and reciprocating blades 86, 90, the blade assembly 40 further includes a 
cam follower, generally designated 92, for engaging the drive actuator 
member 34 in the central recess 50 in the swivel formation 48. The orbital 
eccentric motion of the drive actuator member 34 is translated into 
reciprocating linear action at the reciprocating blade 90 by a blade 
driver lug 94 (best seen in FIG. 4) which extends from the cam follower 92 
and engages a central slot 96 on the blade 90. The lug 94 is preferably 
dimensioned to be tall enough to maintain engagement with the slot 96, 
without interfering with the upper end of the blade locating lug 84. 
Another function of the cam follower 92 is to exert a biasing force on the 
fixed and reciprocating cutting blades 86, 90. Such a biasing force urges 
the reciprocating blade 90 against the fixed blade 86. 
Referring now to FIGS. 2-4, the cam follower 92 preferably consists of a 
single integrally formed piece, fabricated by injection molding or 
equivalent technology. A generally rectangular and flattened base 98 
serves on an upper side as the attachment point for a cam follower 
formation 100. In shape, the formation 100 may be generally forked or 
U-shaped to fit snugly onto the spherical drive actuator member 34. Thus, 
the formation 100 is configured to be driven by the actuator member 34 and 
still permit a wide range of rotational and pivotal motion of the head 
assembly 40 without interfering with the driving action. An important 
feature of the head assembly 40 is that it is rotatable 360.degree. 
relative to the coupler end and is also pivotable approximately 30.degree. 
from a base position as shown in FIG. 1. 
A result of the engagement of the forked cam follower 100 on the spherical 
drive actuator member 34 is that the driving lug 94 is maintained at a 
constant diametrical distance from the member 34 throughout a wide range 
of motion, regardless of the orientation of the head assembly 40 to the 
coupler assembly 30. This engagement is important for achieving the 
rotatability of the head assembly 40 relative to the coupler formation 30. 
The formation 100 also is long enough to project through the opening 58 
and into the recess 50 defined by the swivel formation 48. The cam 
follower formation 100 is generally opposite the location on the base 98 
from which depends the blade driver lug 94. 
Located laterally adjacent each side of the cam follower formation 100 on 
the base 98 is an integrally formed, resilient, upwardly or vertically 
inclined wing formation 102. The wings 102 are constructed to resist a 
downwardly directed vertical force, and thus exert a biasing force on the 
base 98 near the driver lug 94. As such, when the cam follower 92 is 
assembled into the housing 42, the wings 102 will engage the underside of 
the upper surface 68 of the first housing portion 44, and accordingly will 
cause the base 98 to exert a biasing force against the uppermost 
reciprocating blade 90. The reciprocating blade 90 will slidingly engage 
the fixed blade 86, and the blades 86, 90 will thus be biased against each 
other and the floor 72. 
Referring now to FIGS. 2, 4 and 5, the blades 86, 90 will be described in 
greater detail. A principal feature of the present invention is that 
although the blades 86, 90 have been designated as separate components and 
have different functions in the assembly 40, they may be identical in 
construction. In other words, depending on the finishing operations 
employed, the same component may either be used as a fixed blade 86, or as 
a movable blade 90. Each blade 86, 90 has a wide edge 104, a narrow edge 
106, and a pair of angled sides 108. Each edge 104, 106 preferably serves 
as a cutting edge, with the edge 104 serving as the fixed edge, and the 
edge 106 as the moving or reciprocating edge. The blades are preferably 
stamped from stainless steel to prevent corrosion. 
Each of the wide and narrow edges 104, 106 has a respective plurality of 
teeth 110, 111. Generally, differences in tooth shape and spacing of the 
teeth 110, 111 provide a more efficient cutting action than when identical 
tooth patterns are used for both blades 86, 90. More specifically, the 
teeth 110 on the wide edge are rounded or radiused at their tips to avoid 
nicking or cutting the subject. Conversely, the tips of the teeth 111 on 
the narrow edge are truncated or cut off to provide sharper corners for 
cutting. Further, in the present embodiment, the teeth 111 are spaced 
farther apart and the side cutting edges have a greater rake angle than 
the teeth 110. It should be noted that, based on application of the 
product and manufacturing requirements, either or both of the relative 
rake angle and spacing of the teeth may vary. It will be seen that the 
wide edge 104 has a wider outside tooth 112 at each end thereof. These 
outside teeth 112 allow more protection against cutting and nicking of the 
skin by the edge 106. 
On each blade 86, 90 a central web portion 114 is vertically offset from 
the edges 104, 106, so that when the blades 86, 90 are placed upon each 
other in opposing operational relationship in the housing 42, as seen in 
FIG. 4, a space 116 is defined therebetween. This construction is 
desirable to minimize the friction between the blades 86, 90 during 
operation by localizing the opposing contact areas of the blades to the 
region along the edges. On the web portion 114 is found the centrally 
located slot 96, as well as an elongate guide slot 118 on each side of the 
central slot. Each guide slot 118, also termed an engagement formation, is 
dimensioned to slidingly accommodate one of the blade guide bosses 88, and 
is long enough to accommodate the reciprocal stroke of the reciprocating 
blade 90. The length of the stroke is determined by the dimensions of the 
eccentric member 28, as is known in the art. The slots 118 are parallel to 
the narrow and wide edges 104, 106. 
Referring now to FIG. 4, it will be seen that the reciprocating blade 90 is 
slightly offset laterally away from the fixed blade 86. This relative 
position of the blades is intended to prevent nicking and/or cutting the 
skin of the person whose hair is being clipped. The offset relationship is 
provided by placing the guide slots 118 slightly closer to the narrow edge 
106 than to the wide edge 104. In a preferred embodiment, the guide slots 
118 are on the order of 0.012 inch closer to the narrow edge 106. 
In other words, given a centerline of the blades 86, 90 taken parallel to 
the edges 104, 106, the guide slots 118 are offset from the centerline. A 
function of this offset construction is when an offset distance X is 
desired between the fixed and moving blades 86, 90, and the blades are 
identical in configuration, the offset of the guide slots 118 from the 
center line is 0.5.times.. 
In operation, the blade assembly 40 is assembled by placing a fixed blade 
86 upon the blade locator lug 84 and upon the base 89 on the floor 72 so 
that the teeth 110 extend out the open side 82. At this time, the top of 
the blade guide bosses 88 will extend through the guide slots 118, but 
provide no guidance since the blade is fixed. The bosses 88 guide the 
reciprocating blade 90 relative to the fixed blade 86. The reciprocating 
blade 90 is placed upon the taller guide bosses 88 so that its narrower 
edge 106 extends out the open side 82, and is inverted relative to the 
fixed blade 86 so that the space 116 is formed between the two blades. 
However, the opposing toothed edges 104 and 106 will be in sliding contact 
with each other (best seen in FIG. 4). Although the guide bosses 88 engage 
the guide slots 118, the blade locator lug 84 does not engage the 
reciprocating blade 90. Thus, when identical parts are used for both the 
fixed and moving blades 86, 90, one blade is flipped over and reversed 
front-to-back relative to the other blade. 
Next, the cam follower 92 is disposed upon the reciprocating blade 90 so 
that the blade driver lug 94 is inserted into the central slot 96. The lug 
94, as is the locator lug 84, is dimensioned to be tightly accommodated in 
the central slot 96 to prevent unwanted play in the blades 86, 90. The 
driver lug 94 does not engage the fixed blade 86. As the uppermost first 
housing portion 44 is lowered upon the reciprocating blade 90, the cam 
follower formation 100 passes through the opening 58 and extends into the 
central recess 50 of the swivel formation 48. Once the first housing 
portion 44 is fastened to the lowermost second housing portion 46, the 
engagement of the resilient wings 102 against the first housing portion 44 
will exert a biasing force against the reciprocating blade 90 to hold that 
blade against the fixed blade 86, and also hold the fixed blade against 
the floor 72 of the second housing portion 46. As seen in FIG. 4, the 
blades 86, 90 are only partially enclosed by the housing 42 and project 
from the open side 82 to engage hair to be clipped. 
Attachment of the blade assembly 40 to the handle portion 12 proceeds by 
engaging the swivel portion 48 about the first coupler 30 portion of the 
handle portion. The clamping tabs 54 are spread slightly to accommodate 
the insertion of the first coupler portion, but then retract over the 
drive end 14 to secure the components together. 
At the same time, the forks of the cam follower formation 100 snugly fit 
onto the drive actuator member 34. Upon assembly, the blade assembly 40 
has 360.degree. of rotational movement and substantial pivotal movement in 
the range of 30.degree., and is able to be positioned by an operator or 
technician in a wide variety of angular orientations to facilitate 
clipping. Also, the eccentric rotation of the drive actuator member 34 is 
translated by the cam follower 100 into the linear reciprocating movement 
of the blade 90 relative to the blade 86 regardless of the angular 
orientation of the blade assembly to the handle portion 12. 
A significant advantage of the construction of the clamping tabs 54 and the 
cam follower 100 is that the operator may readily align and attach the 
blade assembly 40 upon the handle portion 12 by merely exerting an axially 
directed pushing force upon the blade assembly towards the handle portion. 
Unlike conventional designs, there is no special alignment or manipulation 
required to achieve proper engagement of the blade assembly upon the 
handle, and engagement of the cam follower may be accomplished in a single 
operation. 
Upon completion of the clipping operation, the operator or technician may 
place the clipper 10 near a disposal container. The tab 64 is pressed by 
the operator's thumb or finger in the direction of the indicator arrow 66, 
and the entire blade assembly 40 will pop off into the disposal container 
without requiring the operator to come in contact with the sharp blades 
and may easily be accomplished using only the same hand holding the unit. 
Prior art clippers with detachable heads require two hands or the touching 
of blades by the operator, which may expose the operator to contamination. 
While a particular embodiment of the clipper blade assembly of the 
invention has been shown and described, it will be appreciated by those 
skilled in the art that changes and modifications may be made thereto 
without departing from the invention in its broader aspects and as set 
forth in the following claims.