A power-operated tweezers device for plucking hairs includes a reciprocatable member coupled to a motor, tweezers, a lost-motion coupling between the reciprocatable member and the tweezers effective to move the tweezers to an extended position only during a first part of the forward stroke of the reciprocatable member, and to a retracted position only during a first part of the return stroke of the reciprocatable member; and means effective to move the tweezer jaws to their closed positions during a last part of the forward stroke of the reciprocatable member, and to their open positions during a last part of the return stroke of the reciprocatable member.

FIELD AND BACKGROUND OF THE INVENTION 
The present invention relates to a power-operated tweezers device for 
plucking hairs. 
A number of power-operated tweezers devices are known in the patent 
literature, examples, being described in U.S. Pat. Nos. 4,171,701, 
2,592,484, 2,123,860, 2,082,263 and 2,025,006 and in French Patent 
1,393,532. The advantages of power-operated tweezers are well known, 
particularly the reduction in pain when the plucking is done quickly so as 
exceed the reaction time of the sensory nerve. Nevertheless, 
power-operated tweezers have not yet found widespread use probably because 
of the complicated construction generally involved in the previously 
described devices, and/or the inability of the device to pluck the hairs 
at a sufficiently high speed to reduce or eliminate the pain. In addition, 
most of the power-operated tweezer devices include but a single pair of 
jaws which makes the use of the device a slow and tedious operation. 
OBJECTS AND BRIEF SUMMARY OF THE INVENTION 
An object of the present invention is to provide a power-operated tweezers 
device having advantages in one or more of the above respects. 
According to a broad aspect of the present invention, there is provided a 
power-operated tweezers device for plucking hairs, comprising: a motor 
fixed with respect to a base; a reciprocatable member coupled to said 
motor so as to be driven through a forward stroke to an extended position, 
and through a return stroke to a retracted position; tweezer means 
including a pair of arms having jaws movable to an open position to 
straddle a hair to be plucked, or a closed position to clamp the hair 
therebetween; a lost-motion coupling between said reciprocatable member 
and said tweezer means effective to move the tweezer means to an extended 
position only during a first part of the forward stroke of the 
reciprocatable member, and to a retracted position only during a first 
part of the return stroke of the reciprocatable member; and tweezer 
closing-opening means effective to move the tweezer jaws to their closed 
positions during a last part of the forward stroke of the reciprocatable 
member, and to their open positions during a last part of the return 
stroke of the reciprocatable member. 
Two embodiments of the invention are described below for purposes of 
example. In both embodiments, the lost-motion connection includes a pin 
fixed to the base and received within a long slot formed in the 
reciprocatable member and a short slot formed in the tweezer means. 
According to further features in both described embodiments, the motor is a 
rotary motor having a rotary shaft and is coupled to the reciprocatable 
member by an eccentric rotated by the rotary shaft. In addition, the 
rotary shaft rotates a worm gear meshing with a gear wheel eccentrically 
coupled to the reciprocatable member. More particularly, the 
reciprocatable member is a reciprocatable plate movable on the base and 
constrained to reciprocal movements by pins fixed to the base movable in 
slots formed in the plate. 
In one described embodiment, each of the pair of arms of the tweezer means 
includes a single jaw. 
In a second described embodiment, each of the pair of arms of the tweezer 
means carries a plurality of jaws, the jaws of one of the arms being 
openable and closable with respect to the jaws of the other arms. 
Further features and advantages of the invention will be apparent from the 
description below.

DESCRIPTION OF PREFERRED EMBODIMENTS 
The Embodiment of FIGS. 1 and 2a-2d 
The device illustrated in FIGS. 1 and 2a-2d comprises a base plate 2 
supporting an electric rotary motor 4 whose rotary shaft 6 drives a worm 
gear 8 meshing with a gear wheel 10. A reciprocatable plate 12 is coupled 
to gear wheel 10 by a crank arm 14 pivotally connected at one end by pin 
16 to the reciprocatable plate, and pivotally connected at its opposite 
end by pin 18 to gear wheel 10 eccentrically with respect to the center 
shaft 20 of the gear wheel. It will thus be seen that the operation of 
motor 4 will cyclically drive plate 12 through forward strokes to an 
extended position, and through return strokes to a retracted position. 
This movement of the plate 12 is constrained to reciprocatable movements 
by a pair of pins 21, 22 fixed to base plate 2 and movable within a pair 
of slots 24, 26 formed in reciprocatable plate 12. 
A pair of tweezers, generally designated 30, is carried by reciprocatable 
plate 12 between the latter's slots 24, 26. Tweezers 30 include a pair of 
arms 32, 34 connected together at one end by a bridge section 36 and 
terminating at their opposite ends in jaws 38, 40. The tweezer arms 32, 34 
are sufficiently elastic such that the two jaws 38, 40 may be moved to an 
open position in order to straddle a hair to be plucked, or to a closed 
position to clamp the hair between the jaws. 
The tweezers 30 are coupled to the reciprocatable plate 12 by a lost-motion 
coupling, which includes a pin 42 fixed to the base plate 2 and movable 
within a short slot 44 formed in the bridge section 36 of the tweezers, 
and a long slot 46 formed in plate 12 aligned with slot 44 in the bridge 
section 36 of the tweezers. As will be described more particularly below, 
this lost-motion coupling is effective to move the tweezers 30 to an 
extended position only during a first part of the forward stroke of the 
reciprocatable plate 12, and to a retracted position only during a first 
part of the return stroke of the reciprocatable plate. Slots 24, 26 and 46 
in the reciprocatable plate 12 are all of the same length, equal to the 
length of the forward and return strokes. Slot 44, however, in the bridge 
section 36 of the tweezers 30, is of substantially smaller length so that 
the tweezers will close just before the end of the forward stroke and will 
open just before the end of the return stroke. In the described example, 
slot 44 is one-half the length of slots 24, 26 and 46, so that the 
tweezers will close during the last half of the forward stroke and will 
open during the last half of the returns stroke. 
The illustrated device further includes tweezer closing-opening means 
effective to move the tweezer jaws 38, 40 to their closed positions during 
the last part of the forward stroke of the reciprocatable plate 12, and to 
their open positions during the last part of the return stroke of the 
reciprocatable plate. Such tweezer closing-opening means comprises a pair 
of links 50, 52 pivotally mounted at their outer ends by pins 54, 56 to 
the reciprocatable plate 12, and coupled at their inner ends to the two 
arms 32, 34 of the tweezers. 
The operation of the device illustrated in FIG. 1 is shown in FIGS. 2a-2d. 
FIGS. 2a and 2b illustrate the movement of plate 12 through the forward 
stroke to an extended position, and FIGS. 2c and 2d illustrate the 
movement of the plate through a return stroke to its retracted position. 
Thus, FIG. 2a illustrates the top dead-center position of the 
reciprocatable plate 12 at the beginning of its forward stroke. In this 
position, the plate is in its retracted position, and similarly the 
tweezers 30 is in its retracted position, but with the jaws 38, 40 of the 
tweezer arms in their open position. Pin 42 of the reciprocatable plate 12 
is at the bottom of slot 44 formed in tweezer bridge section 36. 
Assuming the eccentric 10 rotates counter-clockwise, as shown by the arrows 
in FIGS. 2a-2d, it will be seen that: (a) during the first-half of the 
forward stroke of reciprocatable plate 12, both plate 12 and the tweezers 
30 are moved to their extended positions until pin 42 engages the upper 
end of slot 44 on the tweezers bridge section 36, which thereby arrests 
the downward movement of the tweezers (FIG. 2b); (b) during the second 
half of the forward stroke, plate 12 continues to move to the extended 
position whereby the links 50, 52, engaging the arms 32, 34 of the 
tweezers, move the tweezer jaws 38, 40 to their closed positions (FIG. 
2c); (c) during the first half of the return stroke, plate 26 moves 
towards its retracted position with the tweezers also being moved towards 
the retracted position and with the tweezer jaws 38, 40 closed (FIG. 2d), 
until pin 42 engages the lower part of slot 44 (FIG. 2d); and (d) during 
the second half of the return stroke, plate 12 is moved to its fully 
retracted position whereupon the tweezer jaws 38, 40 are opened (FIG. 2a). 
The Embodiment of FIGS. 3 and 4a-4d 
FIGS. 3 and 4a-4d illustrate a power-operated tweezers device in which each 
of the pair of arms of the tweezers carries a plurality of jaws, rather 
than a single jaw, with all the jaws of one arm being openable and 
closable with respect to the jaws of the other arm. 
Thus, the device of FIGS. 3 and 4a-4d includes a base 102 mounting an 
electric motor 104 having a rotary output shaft 106 driving a worm gear 
108 meshing with a gear wheel 110. The device also includes a 
reciprocatable member 112 reciprocated by the motor via a crank arm 114 
pivotally mounted by a pin 118 to the gear wheel 110 by a pin 118 
eccentric with respect to the gear shaft 120. In this case, the base 102 
includes a base plate 102a and a pair of side bars 102b, 102c joined at 
their outer ends by a crossbar 102d, defining a guide for guiding the 
reciprocations of the reciprocatable member 112. The reciprocatable member 
112 is made of two sections 112, 112b which are moved together in unison 
by pin 116. 
A tweezers assembly, generally designated 130, is carried by the 
reciprocatable member 112 and includes a pair of arms 132, 134 joined at 
one end by a bridge section 136, and carrying a plurality of jaws at their 
opposite ends. 
Whereas FIGS. 4 and 4a-4d illustrate only one jaw 138, 140, carried on each 
of the two arms 132, 134, it will be appreciated that each of the two arms 
carries a plurality of jaws 138, 140, with the jaws of one arm being 
openable and closable with respect to the jaws of the other arm. Thus, the 
free ends of the two arms 132, 134 are formed with a plurality of slits 
138a-138n for arm 132, and slits 140a-140n for arm 134, which slits 
receive their respective pincer jaws 138 and 140. 
A pin 142 fixed to the base 102 on one side, and to the crossbar 102d on 
the opposite side, is received within a short slot 144 formed in the 
tweezers bridge section 136, and in a pair of long slots 146 formed in the 
two sections 112a, 112b of the reciprocatable member 112. 
The two tweezer arms 132, 134 are coupled to the reciprocating member 112 
by a pair of links 150, 152. Each link is pivotally mounted at one end 
154, 156 to the reciprocatable member 112, and at its opposite end 158, 
160 to the two arms 132, 134 of the tweezers assembly. 
As in the embodiment described above with respect to FIGS. 1 and 2a-2d, 
slot 144 in the tweezers bridge section 136 is of substantially shorter 
length (e.g., one half) than the long slots 146 formed in the two sections 
112a, 112b of the reciprocatable member 112. This arrangement, therefore, 
provides the same type of lost-motion coupling between the reciprocatable 
member 112 and the two arms 132, 134 of the tweezers assembly 130, to 
produce the same operation as described above with respect 
to FIGS. 2a-2d. 
FIGS. 4a-4d illustrate the movements of the two tweezer arms 132, 134, and 
particularly their jaws 138, 140, during a complete cycle of operation of 
the device. In the construction illustrated in FIGS. 4 and 4a-4d, the 
reciprocatory movements of the reciprocatable member 112 are guided by pin 
142 fixed to the base 102, and also by the two side bars 102b, 102c fixed 
to the base. 
The two arms 132, 134 of the tweezers assembly 130 are formed with 
reduced-thickness sections, as shown at 133, 135, respectively, to permit 
the two arms to be flexed towards and away from each other when closing 
and opening the tweezer jaws. 
While the invention has been described with respect to two preferred 
embodiments, it will be appreciated that many variations may be made. For 
example, the tweezer arms may be pivotally mounted to each other, rather 
than joined together by an elastic bridge section. Many other 
modifications and applications of the invention will be apparent.