Note: Descriptions are shown in the official language in which they were submitted.
~2~3~3~
This invention relates to the field of rotating
toys. More specifically, the invention relates to a
yo-yo* type toy wherein the axle of the yo-yo is sus-
pended from a twist-resistant support, such as a
twist-resistant string, chain, tape or other material
offering a greater torsional resistance to twis-tin~
than the conventional yo-yo string.
A yo-yo consists of a single axle having two
parallel positioned discs centrally connected to the
axle. In one modification of a yo-yo, a string is
tied at one of its ends to the axle be-tween the dis~s
and is held in the user's hand at the other end. The
string is wrapped around the axle, and the body o the
yo-yo is allowed to fall, thereby imparting a rota-
tional momentum to the discs in association with their
translational motion. This rotatiollal momentum causes
the yo-yo body to rise upward again, after it reaches
~he bottom of its swing. A gentle upward impulse
applied to the yo-yo near the bottom of its swing
compensates for ~he ener~y lost through friction.
In another variation of the yo-yo, the string is
not actually tied to, or anchored to, the axle;
*Trademark
~3~73~
r~ther, it is looped about the axle somewhat loosely,
allowing the yo-yo body to spin freely in the looped
strlng. Such rotational motion of a yo yo body,
unaccompanied by ~ranslational motion along the string
dixection, is referred to as "sleeping". The "sleep-
ing" yo-yo can be withdrawn from its "~leep" by jerk-
ing the string, or alternatively, by relaxing the
tension in the string.
A yo-yo is subject to a particular problem when
used by children or inexperienced players. Generally
the yo-yo leans over to one side and then undergoes a
pronounced rotation about the axis of the string. At
this point, the yo-yo is generally out of control.
The inventor a~tributes this problem, in part, to
p~ecession, and considers it to be the most serious
problem with yo yo operation~
When a torque is applied to a rotating body
tending to displace the original axis of rotation, the
body reacts by rotating about an axis which is ortho-
gonal to both the original axis of rotation and the
axis of the applied torque. This phenomenon is called
precession and has been studied extensively in con-
junction with conventional gyroscopes and spinning
tops, but not in conjunction with yo-yos. The direc-
tion of the induced precessional rotation can be
predicted from a knowledge of the original direction
of spinning and of the direction of the applied
torque. The inventor has chPcked these aspects out
experimentally with yo-yos and confirmed that the
basic difficulty with yG-yo operation is due to the
twisting of the yo yo about the axis of the string and
that this is due, at least in part to the phenomenon
of precession.
Operation of a yo~yo would be simplified if the
precessional problem were eliminated or minimizPd.
One way for achieving thls is to use a support ma-ter-
ial which offers a significant resistance to twisting
3 ~3~3~
about an axis lying along the length of the support,
but which, at the same time, is sufficiently flexible
to wrap around the yo-yo axle. Such a support hinders
precessional rotation, or rotation Idue to any other
cause, about the support axis.
In the specification and claims of this applica-
tion, the term "twist-resistant support" means that
the support offers a significant barrier or opposition
to twisting about the longitudinal axis of the support
compared to conventional yo-yo strings which have been
used on commercial yo-yos up to the present time. Of
course, in order to be useful for a yo-yo, such a
twist-resistant support must be flexible about axes
transverse to the longitudinal axis of the support in
order that the support may wind about the yo-yo axle.
As an indication of the increased versatility of
the yo-yo presented herein, the u~er will find that
the yo-yo can be handled quite roughly during its
operation, and still, the user continues to retain
control o~ its motion. The ability of the twist-
resistant support to resist twisting about its longi-
tudinal axis hinders the yo-yo from engaginy in
rotation about the axis of -the support and also faci-
litates the yo yo in recovering from this rotational
motion when such does occur.
The presenkly claimed invention is comprised
in one embodiment of a single axle which connects
two parallel discs at their centers. A twis-t-resistant
support is connected to the axle between the discs. In
one modification of the invention, the twist-resistant
support is tied to the axle, preven-ting the yo-yo from
sleeping. In another modification. the twist-resist-
ant support is looped about the axle, allowing the yo-
yo to sleep.
In describing the association of the twist-resist-
ant support with the yo-yo axle herein, the following
-? ~
~Z~3~3~
terminology is adopted: "tied to" means that the t~ist-
resistant support is tightly secured to, anchored to, or
embedded in, the axle, preventing the yo-yo froln sleeping;
"looped aboutl' means that the twist-resistant suppor-t
loosely encircles or surrounds the axle in any manner
which allows the yo-yo ko sleep; "connected to" means that
the twist-resistant support is associated with the axle in
either of the above two ways 7 that is, "connected to"
embraces both "tied to" and "looped about".
In a particular embodiment of the present
invention, a system of one or more swivels is a-ttached to
the end of the twist-resistant support opposite the end of
attachment to the axle. A holding ring is attached to the
swivel system. In order to operate the preferred
embodiment of the present invention, the user places his
finger through the holding ring. After wlnding the
support around the axle, the body of the yo-yo is allowed
to fall. Thereafter, gentle up and down oscillatory
motion is maintained to keep the body of the yo-yo
rotating, and thus sustaining its vertical up-and-down
motion. The swivel system, if present, and including one
or more swivels, allows relaxation of the rotational
tension in the support resulting from twisting of the
support about a vertical axis. This significantly
facilitates operation of the toy.
In accordance with t~e invention, there is
provided a toy capable of combined rotational motion about
a horizontal axis and translational motion in a vertical
direction, comprising, an axle, a first disc connected at
a center point to the axle, a second disc connected at a
center point to the axle, a twist-resistant support
connected at one end to the axle at a position between the
first disc and the second disc, the twist resistant
support comprising one of a twist-resistant string, chain,
tape, ribbon or metallic cord.
~2373~
Another object of the present invention is to
provide a yo-yo toy that is more smoo-th in operation
than a conventional yo-yo toy.
Still another object of the present invention
is to present a yo-yo toy with enhanced visual effects
due to the presence in a preferred embodiment of a
tape which may include indicia.
Ano-ther ob~ect of the invention is to present
a yo-yo toy which possesses greatly increased stabi-
lity resulting in increased versatility of the function
of the toy.
Another object of the present invention is to
present a yo-yo toy of such design -tha-t difficulties
due to precessional rotation, or o-ther rotation about
the axis of the suppor-t, can be readily rectified
and proper yo-yo operation reinsta-ted without having
-to stop the yo-yo and start all over again.
Another object of this invention is to present
in a further preferred embodiment a tape-supported
yo-yo where the axle is slightly elliptical, rather
than circular, in cross-section.
These and other objects and advantages of the
present invention will become apparent to those
skilled in the art upon reading the details of con-
struction and use as more fully set forth below,
~ 3 ~
reference being made to the accompanying drawings
forming a part hereof wherein like numerals refer to
like parts throughout.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a front view of a yo-yo illustrating
the phenomenon of precession;
Figure 2 is a front view of an apparatus con
structed to measure and compare the torsional resist-
ances of various support materials;
Figure 3 is a front view of one e~bodiment of the
present invention incorporating a twist-resistant
string;
Figure 4 is a front view of an embodiment of the
present invention incorporating a tape;
Figure 5 is a front view of another embodiment of
the present invention incorporating a tape-cum-string
combination;
Figure 6 is a front view of an embodiment of the
tape-cum-string combination where the string pene-
trates the length of the tape segment; and
Figure 7 is a cross-sectional ~iew of the axle in
one embodiment of a tape-supported yo-yo having an
elliptical axle.
DESCRIPTION OF THE PREFERRED_EMBODIMENTS
Before the present "yo-yo with ~wist-resistant
support" is described in detail in terms of its pre-
ferred embodiments, it is to be understood that this
invention is not limited to the particular arrangemen-t
of parts shown, as such devices may, of course, vary.
It is also to be understood that the terminology used
herein is for the purpose of describing particular
embodime~ts only and is not intended to be limiting.
Referring now to the drawings, Figure 1 illus-
trates the phenomenon of precession as it relates to a
spinning yo-yo. The body of the yo~yo is referred to
generally by the number 1. The body contains a single
~3~
a~le 2. The axle 2 has a pair of identical discs 3
positloned at their center points on the axle 2.
Imagine the yo-yo ~ody 1 to be spinning about the
axis 5-5 such that the "+" symbols on discs 3 indicate
that those portions of the discs are rising from the
plane of the page; the "-" s~mbols indicate that ~hose
portions of the discs 3 are descending into the plane
of the page. The string 4 is being pulled to the
side, tending to topple the yo-yo body 1 in a clock-
wise manner as viewed facing Figure 1, and as indi-
cated by the arrows 6. It is a well-kno~n principle
of physics -that, when a torque is applied to a rotat-
ing object, which tends to displace the origin~l axis
of rotation, the rotating object will rotate about an
axis which is mutually perpendicular to both the
original axis of rotation and to the axis of the
applied torgue. This induced rotation is referred to
as precession. In the case of a yo-yo spinning as
illustrated in Figure 1 and subjected to a torque as
indicated in Figure 1, the yo-yo body 1 will spin or
precess about an axis lying along the line 7-7 and the
direction of precession is indicated by the curved
arrow 8. If either the direction of rotation about
the axis 5-5, or the direction of the applied torque
as indicated by arrows 6 is reversed, the direction of
precessional rotation will be reversed, and will occur
in the opposite direction to that indicated by the
curved ~rrow 8.
The topic of precession has been discuss~d and
studied extensively in the past. In particular, the
precession of spinning tops has been discussed at
length in the literature, for example, in "Spinning
Tops and Gyroscopic Motion" by J. Perry (1850-1920)
republished Dover, New York (1957); "An elementary
Treatment of the Theory of Spinning Tops and gyro-
scopic Motion" by H. Crabtree, Longmans, Green and
8 ~3~
Co., London ~1923); and "A treatise on Gyrostatics
and Rotational Motion" by A. Cray 1918, republished
in 195.9 by Dover, New York. In addition, this topic
has been treated in numerous journal articles. In
contrast, the inventor is not aware of any discussion
in the literature relating to the precession of yo-
yos. When a yo-yo goes out of control, it generally
rotates about the axis of the string. Curiously,
it appears that this rotational motion had not been
attributed to precession until so explained by my
U.S. patents No. 4,290,224 and 4,437,261. Precession
of a yo-yo abou-t the axis of the string had not been
discussed in any prior U.S. patents to the author's
knowledge. Isaacson, U.S. Patent 3,175,326, mentions
the rota-tion of a yo-yo "about the axis of the suspend-
ing string" but does not attribute it to precession.
Isaacson discusses the use of inertial rings in the
yo-yo. However, it is wor-th pointing out here, that,
regardless of the ac-tual moment of inertia of -the
yo-yo body, precession will still occur, as illus-trated
in Figure l, when a torque is applied to the yo-yo
body l which tends to reorientate its original axis
of rotation. A number of commercial yo-yos possess
these "inertial rings" or flywheels in their designs;
this cannot solve, and may actually aggravate, the
precessional problem in yo-yos.
The inventor is not aware of any other paten-t,
or other literature, which addresses the precession
of a yo-yo, as discussed in connection with Figure
l above. The specific information including directions,
provided in Figure l has been checked experimentally
with yo-yos by the inventor and is totally consistent
with predictions based on physical principles (see, for
example, Figure 9.20 in "University Physics" by ~ears
~'
~373~
and Zemansky, 4th edition, Addison-Wesley Publishing
Co., ~1970); or Figure XXII ~page 10) or Figure 19
(page 37) in "An elementary Treatment of the Theory
of Spinning Tops and Gyroscopic Motion" by H. Crab-tree,
Longmans, Green and Co., 1923 loriginally prin-ted
1909 ) .
Rotation of the yo-yo body about the axis of
the support may sometimes be caused by some other
agency and may, in fact, be induced intentionally
as for example in the yo-yo trick Xnown as Sleeping
Beauty by yo-yo players. However, regardless of the
cause of the twisting about the axis of the support,
the present invention serves to elimina-te -this effect.
The precession of -the yo-yo indica-ted by the
curved arrow 8 of Figure 1 could be coun-terac-ted by
applying a torque in the opposite direction to the
curved arrow 8 oE Fiyure 1. Such a -torque can be
supplied by means of the string 4, if the string is
capable of offering a torsional resistance to twisting.
Conventional yo-yo strings offer very little resistance
to twisting and contribute very little to hindering
precession of the yo-yo body. The essence of this
invention is the introduction of supports which display
a significant torsional resistance to twisting and
are thus capable of counteracting the tendency toward
precession by the yo-yo body. The inventor is not
aware of any teachings on these specific concepts
other than that within my ~.S. Patents 4,290,224
and 4,437,261. Specifically, the inventor is not aware
of any use of, or teachings relating to the use of,
twist-resistant supports in association with yo-yos.
... .
.. . _ -- ... . . .. .. . . . .
lo ~373~
The inventor has discovered that substitution of
a twist-resistant support for the conventional yo-yo
stxing successfully counteracts the precessional
problem in yo-yos and leads to a dramatic improvement
in their operability. The inventor has further estab-
lished that a swivel system, consis~ing of one or more
swivels attached to the support material opposite the
end of attachment to the axle, further improves the
operability of the yo-yo. This invention results in a
yo-yo type toy which is easier to operate than a
conventional yo-yo and which can be readily operated
by very young children and by inexperienced adults.
These improvements result from -the torsional resis-
tance to twisting of the support materials, which, in
association with the yo-yo body consitutes the present
invention. An example of a twist-resistant support
material which is particularly effective in associa-
tion with the present invention is a type of twist-
resistant string called metallic cord. Metallic cord
consists of strands of fibers around which thin or
flat metal thread, or simulated metal thread, is
woven. This material is available commercially at a
rather inexpensive cost. One type of such material is
produced by KN~TRIMS of Miami (2431 N.W. 2nd Avenue,
Miami, Florida, 33127). One type of metallic cord
consists of LUREX* woven about multiple strands of
RAYON fibers. In the case of a sleeper yo-yo, it may
be desirable that the twist resistance of the support
be significantly diminished in the immediate vicinity
of the axle, about which it is looped, in order to
facilitate the "sleeping" operation and recovery
therefrom. Another class of twist-resistant material
consists of fine chains, such as those found in
jewelry stores. Such chains offer a considerable
resistance to twistiny, but nevertheless, can readily
wrap around a yo-yo axle. The inventor has discovered
* Trademark
.æ~
23~3~
that a tape or ribbon is also particularly effective
for use with the present invention. In the case of a
tape, other effects in addition to its torsional
resistance to twisting, contribute to the improved
performance of the yo-yo; these aspects wi.11 be dis-
cussed later in this specification. The attachment of
a swivel means, or a swivel means connected to a
holding ring, leads to a signiicant improvement in
the performance and handleability of the new yo-yo.
It should be pointed out that the above specific
twist-resistant supports are quoted simply as partiru-
lar examples, and that the invention is not limited to
the specific items and products named above, but
embraces the generalized concept of a twist-resistant
support in association with a yo-yo type toy.
Conventional yo-yo strings offer very little
torsional resistance to twisting. The essence of the
present invention is the introduction of a twist-
resistant support alone or in combination with a
swivel. The pronounced improvement in the performance
of the yo-yo of the present invention compared to the
conventional yo-yo is readily apparent to a person
using the toy. However, it is desirable to measure
the torsional resistance to twisting of the supports
used in the present inv~ntion in order to show quanti-
tatively that they differ significantly from conven-
tional yo-yo strings.
In order to guantify the torsion-resistance of
various types of yo-yo suppor~s, an apparatus o the
type illustrated in Figure 2 was designed and con-
structed. This apparatus can be applied to strings,
tapes and other materials. Its application to strings
will be described first, followed by a discussion of
its application to tapes. The members 9 and 10 are
vertical supports joined by an upper connector 11 and
a lower connector 1?. The members 13 and 14 are
12 ~2~:3~3~
vertical bars which are connected to supports 9
and 10, respectively. Pulleys 15 and 16 are slidably
connected to bars 13 and 14 by means of clamps 17
and 18, respectively. Hook 19 in upper connector 11
supports the string 20. The string 20 has a split
ring 21 attached at its lower end. The string 20 is
connected, through the split ring 21, to a cylindrical
rod 22 of known diameter by means of a hook 23 which
is screwed into rod 22. A weight 24 is attached to
the lower end of rod 22. A light thread 25 is con-
nected to cylindrical rod 22. The thread 25 lies in
the groove of the pulley 15, and there is a known
mass 26 suspended from the thread 25. A thread 27 is
attached to rod 22 on the opposite side of attach~ent
as thread 25. Thread 25 and thread 27 are attached to
rod 22 at slightly different vertical levels, as
indicated in Figure 2. Thread 27 lies in the groove
of pulley 16 and has a known mass 28 suspended from
it. Weights 26 and 28 are identical. Two series of
parallel holes 29 and 30, are arranged in a vertical
sequence along support members 9 and 10. The plane
containing these sets of holes lies slightly in front
of the plane containing the bars 13 and 14. A remova-
ble pin 31 can be supported at opposite ends in a cor;
responding pair of these holes.
The apparatus is operated as follows: the string
under study is supported from the hook 19 as indicated
above. While disconnected from the s-triny, the rod 22
is manually twisted a specified number of revolutions
in a chosen direction, let's say, clockwise as one
looks down on the rod 22 from the top. This causes
the threads 25 and 27 to wrap around the rod 22 in the
same direction, thereby forcing the two weights 26
and 28 to rise. These wPights exert a torque or mo-
ment on the rod 22 tending to rotate it in the oppo-
site direction to the imposed rotation. After the
~L2~,3'73~
rod 22 has been rotated a specified number of times,
it is connected to the string 20 through the split
ring 21 and hook 23. The torque applied by the two
weights 26 and 28 causes the rod 22 ~o rotate in an
anticlockwise direction as viewed from above, thus
causing the string to be twisted in this direction
also. The rod 22 and attached weight 24 will continue
to rotate until the opposing torque offered by the
twisted string is exactly equal in magnitude to the
torque due to the supported weights 26 and 28, at
which point equilibrium is reached. If the threads 25
and 27 become completely unwrapped from the rod 22
during this process, the same step is repeated ayain,
by disconnecting the rod 22 from the string 20 and
again rotating the rod 22 manually in a clockwise di-
xection, as viewed from the tOp. During this rewind-
ingt the twisted string is prevented from untwisting
by insertion of the pin 31 into the split ring 21,
while the pin 31 is supported in the holes 29 and 30.
The total weight suspended from the string 20 is
given by the sum of the weights of the split ring 21,
the hook 23, the rod 22 and the weight 24, thereby
providing a tension in the string.
The tor~ue or moment applied to the rod 22 by the
weight 26 is given by the product of the weight 26 and
the radius of the rod 22. A similar torque is applied
by the weight 28. Since both weights are equal, and
since both torques act in the same direc~ion, the
total torque is given by the product of one of the
weights by the diameter of the rod. The weight of the
~hreads and the radius of the threads are i~nored in
these calculations due to their very small contribu-
tions to the overall measurments. The end-to-end
distance of strings generally becomes smaller during
twisting; accordingly, clamps 17 and 18 allow the
positions of the pulleys 15 and 16 to be adjusted so
. .. , ., .. . .. . . . . . . _ _ _ _ ... . . . . . .
14 ~ 73~L
that the segment of thread 25 between rod 22 and pul-
ley 1~, and also the segment of thre~d 27 between
rod 22 and pulley 16, are horizontal prior to taking
final measurements.
The torsional resistances of various strings were
compared by counting the number of rotations induced
in a given length of string by a specified torque.
The greater the number of rotations induced i.n a
particular string by a given torque, th~ smaller the
torsional resistance offered by that string. In all
of these measurements, a rod 22 of O.25 inch dia~eter
was used, and the two suspended masses 26 and 28, had
weights of either 1 gram or weights of ~ grams each.
Thus all experiments were carried out under a total
torque of O.25 gram inch or a torque of O.50 gram
inch. The measured data for a number of string mater-
ials are summarized in Table I. All results are the
average of at least six separat~ measurements. Equi-
librium was approached from both directions in all
experiments in order to compensate for frictional
effects within the apparatus. Typically, all indivi-
dual readings fell within 5% of the average value,
indicatiny good reproducibility and precision for the
measurements. Some strings, in particular the cor.ven-
tional looped or double-stranded yo~yo strings offer a
different torsional resistance to twisting in the
clockwise and anticlockwise directions; in those
cases, the number of revolutions reported in Table 1
refers to the average for the clockwise and anticlock-
wise directions.
.... , . .... . ... ., ., .. ... ..... ~ .-- .
~237~
TABLE I
Weight Sus- No. of
Length pended Fro~ Torque Revolu-
Type of String Inches) String (Grams) (Gram Inch) tions
Du~can ~ Yo-Yo 41.75 29.63 0.5 90
String
~esti~al ~ Yo-Yo 40.50 29.63 0.5 90
String
Duracraft ~ 38.25 29.63 0.5 66
Yo-Yo String
Metallic Cord 40.25 29.33 0.5 0.8
Netallic Cord 41.00 29.33 0.5 0.4
Duncan ~ Yo-Yo 44.00 52.15 0.25 56
String
Metallic Coxd 44.00 51.85 0.25 0.13
Metallic Cord 43.50 51.85 0.25 0.40
Braided Nylon 43.00 52.15 0.25 30
t25 Lbs.)
The yo-yo strings listed in Table I were taken from
commercial yo-yos. The data in Table I indicate that
typical yo-yo strings having lengths of about
4Q inches and under a tension of about 30 grams will
undergo significantly more than 40 revolutions when
subjected to a torque of 0.5 gram inch, and undergo
significantly more than 25 revolutions when subjected
to a torque of 0.25 gram inch under a tension of about
50 grams, as measured in the manner described above.
The twist-resistant strings which are the subject of
this application rotate less than 40 complete revolu-
tions under a torque of 0.5 gram inch and a tension
of ~9.33 grams; and rotate less than 20 complete
revolutions under a torque of O.25 gram inch and a
tension of 51.85 grams.
Figure 3 illustrates one embodiment o~ a yo-yo
with twist-resistant string. In this embodiment, the
twist-resistant string 32 is looped 33 about the
axle 2, allowing the yo-yo to sleep. Alternatively,
the twist-resistant string 32 ,may be tied to the
axle 2 in a non-sleeping mode.
The apparatus illustrated in F~igure 2 was also
used to measure the torsional resistances to twisting
of various tape materials.
When a tape is twisted slightly, it produces a
"spiral staircase" typ~ of configuration. Howe~er, i
it is twisted excessively, this configuration col-
lapses and the tape folds over in a pronounced manner
along its width. Tapes differ considerably in their
resistance to this type of collapse, that is, in their
inherent torsional resistance to twisting. When this
type of structural collapse occurs, the tape loses a
significant portion of its torsional resistance to
twisting. When there is a weight supported from the
lower end of the tape, that is, if the tape is under
tension, its total torsional resistance increases; in
other words, this collapse does not occur until a
greater torque is applied to the system. However,
this is not due to the inherent twist-resistance
residing in the ~tape material itself, but is due in
large part to the imposed tension. Accordingly, in
these experiments, it is desirable to have the tension
on the tape as small as possible by having the total
suspended weight from the tape as small as practica-
ble; thus, the weight 24 (Figure 2) was not employed
in the experiments involving tapes.
The torsional resistances of various tapes were
compared by gradually increasing the two weights 26
and 28, that is, by gradually increasing the torque
applied to a fixed length of tape and noting:
(i) How many rotations are induced in the tape
by each applied torque, and
(ii) What magnitude of torgue first causes struc-
tural collapse of the tape.
... _, _ . . _ _ . .. . .
17 ~2~3~3~
The weights 26 and 28 can be varied conveniently
by tying small plastic bags to the ends of the
strings 25 and 27; known masses can then be added to,
and removed from these bags.
In all of these expèriments, a rod 22 of
O.25 inch diameter was used; the plastic bags weighed
0.19 gram each. The support 21 in these experiments
was flat rather than round in order to accommodate the
tape, and weighed 0.37 gram; the rod 22 plus attached
hook 23 had a weight of 2.08 grams. Thws, the tension
in the tape, due to the suspended weight of sup~
port 21, rod 22 and hook 23, had a value of
2.45 grams. The tape was supported at its upper end
by an elongated flat support connected to hook 19.
The measured data for a number of tape materials
are presented in Table Il. The third co:Lumn in
Table II gives the number of rotations induced in each
tape by a specified torgue, for example 1.2/0.3 means
that the tape displayed a total of 1.2 twists from top
to bottom when it was subjected to a torque of 0.3 gram
inch. Column 4 specifies the minimum torque which
causes the "spiral staircase" configuration of the
twisted tape to collapse.
All results are the average of at least three
separate measurements. Equilibrium was approached
from both directions in all experiments in order to
compensate for frictional effects within the measuring
apparatus. All individual readings fell very close to
the average value, indicating good reproducibility and
precision for the measurements.
The commercially available tapes of different
types had slightly different widths. However, it was
possible to choose combinations which had reasonably
close dimensions for comparison purposes, ~r example,
the first four tapes listed in Table II have approxi-
mately the same width; and the 5th, ~th and 7th tapes
. ,.. ,,, .. . .. , . .. ., . ~ ... _ . .. _ .. . ..... . . . .
2 ~73
~ 3 ~L
listed in Table II are also close to each other in
wid~h, allowing valid comparisons to he made.
TABLE II
TWISTS~TORQUECOLLAPSE POINT
TAPE WIDTH (INCH) ~lIGRAM INCH)(GRAM INCH)
Satin 15/1~ 1.2/0.3 0.43
Satin 7/8 1.6/0.3; 2.4/0.550.8
Taffeta Plaid 31/32 1.7/0.3; 2.7/0.550.6
Grosgrain 15/16 0.9/0.3; 2.05/0.8;
(100% polyester) 2.92/1.30;
3.93/2.04;
4.6/2.54 3.~
MYIAR ~ 3/4 2.5/0.3 0.55
Twill Tape 3/4 2.0/0.3 0.35
Grosgrain 11/16 1.6/0.3; 3.1/0.8;
(100h polyester) 4.4/1.30; 5.3/1.82.2
All tapes for these measurements were 42 inches in length
from top to bottom.
Many of the common tapes, such a~ twill ~ape,
Mylar, satin or taffeta plaid, with the dimensions and
texture usually found commercially, do not exhibit a
pronounced degree of torsional resistance to twisting;
accordingly, these materials are not parti~ularly
effective for use in conjunction with a yo-yo. As
shown by the data in Table II, a 42 inch segment of
typical cloth tapes (satin; taffeta plaid3 of widths
between 28/32 inch and 31/32 inch cannot withstand a
torque of 1.0 gram inch under a tension of 2.45 grams;
whereas it requires a torque of 3 gram inch to cause
collapse of grosgrain tape of similar dim~nsions
(42 inches long; 15/16 inches wide~. Similarly, a
42 inch leng~h of twill tape or Mylar, each of
3/4 inch width, cannot withstand a torque of 0.70 gram
inch when supporting a weight of ~.45 grams but a
similar grosgrain tape (42 inche~ in length and
19
~ ~ 3~
11/16 inches in width) can withstand a tor~ue of
2.2 gram inch before its "spiral staircase" configura-
kion collapses. Although all torsional resistance to
twisting is important in connection with this inven
tion, it is most important that the tape not collapse
since collapse of the tape during operation makes it
more difficult and less pleasurable to operate the
toy.
An embodiment of the present invention comprising
a yo-yo body connected to a tape or ribbon support is
illustrated in Figure 4. In ~his embodiment, discs 3
are positioned further apart from each other, leaving
a wi.der groove 34 between the discs. A flat ribbon or
tape 35, of width 36 is connected at one of its ends
to the axle 2. The tape 35 is connected to the axle 2
i~ such a manner that when tape 35 is fully extended,
the edges 37 of the tape 35 are perpendicular to the
axle 2.
A fold 38 is placed at the other end of the
tape 35 by folding the tape 35 over upon itself. This
fold is maintained by sewing; weaving; stapling;
gluing; etc. A loop 39 passes within the fold 38. A
swivel system 40, containing one or more swivel mem-
bers, is connected to the loop 39. The swivel sys-
tem 40 allows for rotational motion o the support 39
and the attached tape 35 and yo-yo body 1. The swivel
system 40 also facilitates the removal of twists from
the tape 35, when the tape 35 becomes twisted about a
vertical axis.
A ring 41, for holding the yo-yo is connected to
the swivel system 40. ~he entire device may be held
by the user by placing a finger through the ring 41.
The tape 35 may be comprised of a wide variety of
flat elongated material, natural or synthetic. Among
the materials of which the tape 35 may be constituted
are leather, suede, felt, jute, hair, various types of
~.~23~3
skin, fiber glass, various clokh materials, such as
wool, silk, cotton, linen, satin, velvet, carbon
cloth, and/ar synthetic plastics or pol~mers, such as
polyester, polyethylene, polypropylene, polyolefins,
nylon, acrylic, rayon, acetate, or various blends of
the above-listed materials. The tape 35 may have
parallel sides as shown within Figures 4, 5 and 6, or
the sides of the tape 35 may be nonparallel. The
tape 35 may have a woven texture or it may consist of
a non-woven material. However, the inventor ha~ dis-
covered that grosgrain polyester tape or ribborl is
particularly well adapted for use in connection with
the present invention. The essential feature is that
the material can provide a tape of sufficient
torsional resistance. Grosgrain tape is characterized
by having a corrugated pattern with ridges and grooves
normal to the sides 37 of the tape 35. This type of
tape exhibits a signif~cant resistance to twisting
about its longitudinal axis, compared to most cloth
tapes. Consequently, when the grosgrain tape is
forcibly twisted, it has a strong tendency to become
untwisted again. If, during operation of the yo-yo it
is swung to the side, along a direction parallel to
its axis 5-5, it may undergo rotation about the
vertical axis. The twisting which is induced in the
tape as a result of this rotation is readily and
rapidly undone by the propensity of the grosgrain tape
to exist in an untwisted configuration. This untwist-
iny is partially effected through the induced rotation
of the yo--yo body 1 in the opposite direction to the
twisting originally caused by rotation about the
vertical axis. More importantly, the swivel system 40
is very effective in relieving these twists, as a
result of the torque caused by the twisted grosgrain
tape. Another advantage of the grosgrain polyester
tape is its ability to remain straight along its
21 ~ ~ 3~ 3~
width 36, and to resist wrinkling ox warping along
this dimension. Further~ore, if the tape is forced to
become twisted about a vertical a~is, resulting in the
tape adopting a 'spiral staircase' t:~pe of configura-
tion, the corrugated lines still remain in horizontal
alignment, thus maintaining the axle 2 of the yo-yo in
a horizontal orientation.
It is highly desirable to use woven edge ribbon,
rather than non-woven edge ribbon iIl conjunction with
the yo-yo. This eliminates the opportunity for fray-
ing of the ribbon during normal use of the yo-yo. If
non-woven edge ribbon were to be used, some other
means for preventing fraying, such as heat-treat:ment
or other treatment of the edges, would be necessary.
Grosgrain tape is particularly effective for use
with yo-yos. Of course, the other materials such as
twill tape, Mylar, satin, plaid, etc., may become
torsional resistant by increasing their thickness
above the conventional values or through other modifi-
cations of their structure or by treatment. The
desirable feature of a tape for use in conjunction
with a yo-yo is that it possess a significant degree
of torsional resistance to twisting. Based on the
data in Table II, a ribbon-type material suitable for
use as a yo-yo tape should have the following charac-
teristic torsional resistance to twisting: a 42 inch
segment of material of width 15/16 inches, and under a
tension of 2.45 grams, should withstand a torque of
1.O gram inch or more without collapse of its 1'spiral
staircase" coniguration. A 42 inch segment of the
material of width 11/16 inches, and under a tension of
2.45 grams, should withstand a torque of O.70 gram
inch or more without causing collapse of the "spiral
staircase" coniguration of the twisted tape. How-
ever, the inventor has also established that when a
swivel system is used in association with the toy,
~L~2373~
tapes of substantially lesser ~orsional resistance
than those mentioned above may be employed.
The inventor has found that two features of the
invention contribute to improved operational ability.
The features are: (1) twist resistance of the yo-yo
tape and (2) a swivel which releases any twisting
which does occur. By testing various embodiments of
the invention, the inventor has found that the best
results are obtained using twist resistant tape in
combination with a swivel. However, good results can
also be obtained by using a twist resistant tape alone
or by using a swivel in combination with a tape having
no particular ability to resist twisting. More parti-
cularly, the best results are obtained using a swivel
in combination with a tape having a twist resistance
such that a 42 inch segment with a width of 15/16
inches, and under a tension of 2.45 grams, can with-
stand a torque of 1.0 gram inch or more without col-
lapse. However, good results are obtained using such
a tape without a swivel or by using a swivel in com-
bination with a tape having a twist resistance such
that a 42 inch segment with a width of 15/16 inches
cannot withstand a torque of 1.0 gram inch without
collapse. A swivel as referred to herein means any
means which will allow for release of the twisting of
the tape such as a conventional yo-yo string, or a
segment thereof, having very little torsional resist-
ance itself.
The tape 35 may be anchored to the axle ~ by
splitting the axle 2 in two along its length and
inserting the tape 35 between the two halves of the
axle. The tape 35 may be held in this position by
gluing, wedgingr sonic welding, etc. Alternatively,
the tape 35 may be looped about axle 2 in a sleeping
mode. Figure 5 illustrates another sleeping modifica-
tion of the invention. In th.is modification, a string
i
..
23 ~ 3 ~
segment 42, which is connected to tape 35, is looped
about axle 2. The axle 2 contains a groove 43 in order
to maintain the string se~ment 42 centrally located
along the axle 2.
The string 42 ~not used in place of swivel 40)
may be comprised of any of a wide variety of string
materials, natural or synthetic. The type of string
most conventionally used in conjunction with yo-yos is
laid; i.e., it consists of twisted strands. Laid
string is particularly suitable for the situation
where it must be doubled over to form a loop as in the
axle of a sleeper yo-yo; the laid string twists about
itself in two strands very effectively, to form a
loop. This type of string is also very effective in
connection with the present invention. However, other
types of string, such as braided nylon or twine, hemp,
cord, etc., may also be used in association with the
pre ent invention.
It should be pointed out that twist-resistant
string such as metallic cord is particularly effective
in connection with the present invention to connect
the tape 35 to the axle 2, as illustrated in Figure 5,
but not in place of swivel 40.
Another embodiment of the tape-cum~-string combi-
nation is illustrated in Figure 6, wherein the
string 44 is looped about the axle 2; the string 44
enters one end 45 of tape 35 and exits at the opposite
end 46. In this case, the tightness of the loop 33
about the axle 2 may be controlled as in the case of
the conventional sleeper yo-yo.
In the case of a tape-supported yo-yo as illus-
trated in Figure 4, the suspension o the axle 2 from
the width 36 of the tape 35 further adds ~o the ease
of operation of the toy~ In addition, the wrapping of
the tape 35 upon itself during operation of the toy
leads to a smoother motion than in ~he case of the
24 ~3~3'~
conventional string yo-yo, where the string piles on
top of itself in a rather irregular manner, and which
frequently collapses during the winding operation.
A further feature of the tape is that, during
precession of the yo-yo body, the tape acts as a
barrier or '~sail" encountering signiXican~ a~mospheric
resistance and thereby serving to dissipate the pre-
ces~ional rotational energy in the precessing yo-yo.
A tape which resists collapse is desirable in this
context also.
The use of a ribbon or tape 35 provides scope for
introducing decorative and visual effects not possible
with the conventional string yo-yo. For example,
writing, pictures or other colored designs and indicia
may be imprinted on the tape; or the tape may be
comprised of luminous or fluorescent mate:rial to
further add to its attractiveness as a plaything. The
tape-supported yo-yo of the present invention provides
a dramatically different visual impact during opera-
tion compared to the conventional string yo-yo. This
visual impact is due in part to the ability of the
wound tape to slip off, over the rim of one of the
discs, when the yo-yo is thrown to the side, thereby
producing an effect reminiscent of another toy called
a Chinese Yo-Yo.
The yo-yo of the present invention is operated in
essentially the same manner as a conventional yo-yo.
The string 32 (Fig. 3) or tape 35 ~Fig. 4), or tape-
cum-string 35 + 42 (~ig. 5) may b~ wound around the
axle 2 of the yo-yo simply wrapping it by hand. In
the case of a sleeper, the loop 33 must be suffi-
ciently tight to "catch" on the axle 2 during winding.
To initiate operation of the yo-yo, the body l of the
yo-yo may be held in one hand and the end of the
string 32 or the tape 35 or the holding ring 41 may be
held in the other hand. The body 1 of the yo-yo is
~223'73
allowed to fall free while still holding one end of
~he string 32 or of the tape 35 or ring 41. As the
body 1 of the yo-yo falls under the influence of
gravity, the body 1 is forced to rotate about its
axle 2, with consequent unwrappiny of the twist
resi~tant support from around the axle 2. When the
twist-resistant support has become completely unwound,
~he body 1 of the yo-yo has acquired considerable
angular momentum. In the case where the support is
anchored to the axle, this angular momentum forces the
body 1 of the yo-yo to continue rotating, thus winding
the support about the axle 2 in the opposite sense to
the manner in which it was wrapped around the axle
during the previous downward swing. Consequently, the
body 1 of the yo-yo is forced to rise upward again. A
gentle upward impulse applied to ~he support just
prior to the yo-yo body 1 reaching the bottom-most
part of its swing, allows the up-down oscillation of
the yo-yo body 1 to continue indefinitely. This
applied impulse compensates for both frictional loss
of energy and dissipation of the translational compo-
nent of the energy which occurs at the bottom of the
yo-yo swing, when the body 1 of the yo-yo is forced to
change the direction of its translational motion.
In the case of a sleeper, where the axle 2 lies
in the loop 33 of the string or tape, the rotational
momentum of the yo-yo body 1 at the bottom of its
swing zllows the yo-yo to continue rotating in this
position, i.e., sleep, until its rotational kinetic
energy is dissipated by friction. However, if the
rotating yo-yo is brought out of its sleep, the yo-yo
body 1 will again travel up along the support, the
distance of rise depending or the amount of rotational
kinetic energy remaining in the yQ-yO. The rotating
yo~yo may be brought out of its sleep by jerking the
support, or alternatively, by relaxing the tension in
the support.
~ ~ 3~ ~
The most advantageous feature of the present
yo-yo compared to the conventional yo-yos and prior
modifications thereof, is its facility to recover,
e~en after experiencing gyroscopic precession. For
example, if during operation of the yo-yo it is swung
sideways, that is, in a direction parallel to the
yo-yo axis 5-5, it experiences a gyroscopic precession
about a vertical axis; this behavior is common to all
yo-yos and ~enerally results in total loss of control
over the yo-yo motion. However, in the case of the
yo-yo of the present invention, the twist-resistant
support, in conjunction with the swivel system, coun-
teracts the precessional rotation and the problem is
rapidly and automatically eliminated. Rotation about
the axis of the string, caused by any other means, is
similarly eliminated.
It is possible to fabricate the body 1 of the
yo-yo from a variety of materials, such as wood;
plastic, metal; rubber composite, etc. The body 1 of
the yo yo could be molded or turned as one complete
unit, or the disc 4 and axle 2 portions could be made
separately and then fastened together by various
means, including but not limited to gluing; screwing;
wedging; soldering; welding; etc. The axle 2 may or
may not contain the groove 43.
One of the modifications incorporating a twist-
resistant string which the inventor found to work
effectively employs two discs, each of 57 millimeters
diameter and separated from each other by 2.5 milli-
meters by means of an axle of 6 millimeter diameter.
The string consists of a 102 centimeters length of
metallic cord, manufactured by KNITRIMS of Miami
(2431 N.W. 2nd Avenue, Miami, Florida 33127~, and is
anchored to the axle by wedging one end of it between
~he axle and one of the discs during assembly of the
yo-yo. These yo-yos also wor~ effectively when
~22373~
suspended from a swivel system ~consisting of fisher-
man's swivels) and a holding ring.
In the case of a tape-supported yo-yo, the inven-
tor has found that ~ tape width of 16 millimeters or
22 millimeters ~orks particularly well when the tape
is composed of grosgrain polyester, and connected to
an axle having a diameter of 6 millimeters, which is
in turn connected to discs having diameters of 52 mil-
limeters. A swivel system is connected to ~he other
end of the tape and a holding ring is attached to the
swivel system. However, much wider ribbons, even up
to 57 millimeters in width, have been found very
effective when used in conjunction, with the present
yo-yo.
When the yo-yo is assembled by inserting the tape
between two axle halves, the circurnference of the axle
may be slightly non-circular or elliptical rather than
circular; this effect is desirable as it tends to
compensate for the bulge occurring where the tape
exits from the axle, thereby leading to a smoother
operation of the yo yo. This is illustrated in Fig-
ure 7 where the "diameter" 47 is slightly longer than
l'diameter" 48. This non-circularity or ellipticity
compensates for the bulge 49 produced where the
tape 35, emerging from the space between ~he two axle
halves 50, folds over in order to wrap around the
axle. The axle halves 50 may be designed so that the
assembled axle is slightly non-circular or elliptical
even in the absence of the thickness due to the tape
itself. Typi~al cross-sectional dimensions for the
axle in an assembled (i.e. with tape inserted) yo-yo
are a length 47 of 35/128 inch and a length 48 of
32/128 inch. Approximately 2/128 inch of length 47
is contributed by the tape when grosgrain polyes~er
i~ used. This slight non-circularity or ellipticity
in the axle is not absolutely necessary but does con-
tribute to a smoother motion.
28
~373~
The instant invention is shown and descxibed in
what is considered to be the most practical and pre-
exred embodiment. It is recognized, however, that
departures may be made therefrom, wh:ich are within the
scope of the invention, and that obvious modifications
will occur to one skilled in the art upon reading this
di~sclosure.
