Method for an Oscillating Moving Display
An efficient battery powered oscillating mobile comprises of a mobile, elastic cord, free standing module assembly, plurality of keeper fasteners, and external rigid anchor point. The mobile comprises of an outer shell, which comprises of a printed circuit board assembly, hole, tab, and cord. The printed circuit board assembly comprises of a printed circuit board, motor, motor shaft, metal arm, and cross beam. Each keeper fastener comprises of keeper fingers, blade screwdriver slot, keeper head, and keeper shaft. The free standing module comprises of a power source assembly, housing mechanism, motor assembly, catch, catch slot, plurality of slots, sliding guide, printed circuit board assembly, electrical contact pin, plurality of retainer holes, snap locks, switch spring system, cord adaptor, coin cells, and keeper spring.
The current application claims a priority to the U.S. Provisional Patent application Ser. No. 61/428,789 filed on Dec. 30, 2010.
FIELD OF THE INVENTIONThe present invention relates generally to battery powered mobiles that can oscillate through its own mechanisms.
BACKGROUND OF THE INVENTIONOne type of traditional mobile is designed to rotate when suspended by a cord and hung outside and exposed to a breeze. For other mobiles, it is desired to enable a decorative mobile to rotate while suspended indoors where there is not an adequate breeze to energize it. Battery powered modules containing DC motors with a reduction gear set to reduce the motor shaft from thousands of rpm down to sub-10 rpm are presently sold for this purpose. Typically, these mobiles are mounted from a ceiling or other overhead horizontal surface with the output shaft oriented vertically downward to support the mobile by a string or cord. Because of the size of and weight necessary to operate these modules, they must generally be mounted from a rather substantial supporting surface. The term mobile will be used to describe any assembly or assemblage which is suspended by either a flexible or non-flexible member whose length is greater than 100 times the square root of the cross sectional area of the suspending member and rotated by a mechanical or electromotive device.
These modules usually have an on/off switch such that, in the on position, the DC motor continuously rotates the suspended mobile. Some units even have a timing circuit that turns the motors on and off at a pre-defined duty cycle. Others have light sensing devices than only turn the module on when light is present. The disadvantage of these mechanisms is their inefficient use of electrical power. Even pairs of relatively large (i.e. D cell) batteries, wherein the modules only operate when light is present and operate on a low duty cycle, such as 25%, only have a battery life of a few weeks because the mobile only rotates when the motor is powered and most of the battery power is used to rotate the motor and drive reduction rather than rotating the mobile itself. Since these modules impart a low, fixed rotation speed in one direction only when energized, the rotation is repetitive and un-interesting, especially when displayed in groups. Because they are often ceiling mounted, changing batteries is inconvenient and the large batteries costly.
Currently, there are many Christmas tree rotating ornament devices. However, they can only be powered by being plugged into light sockets on existing strings of Christmas tree lights, which make the rotating devices awkward to use and store. These rotating ornament devices are external to the mobile or ornament being rotated thereby taking up space without providing any aesthetic value. They also suffer from running continuously at a constant speed, which becomes monotonous and uninteresting. In addition continuously running motors create an undesirable noise. Because the self-contained module, made up of a motor, batteries and on-off switch, is very efficient, it is small enough that it can reside within the ornament itself in many cases.
In the current invention, the mobile or other object to be rotated is supported by an elastomeric cord or multiple strands of filaments connected directly between the object to be rotated and the motor output shaft with or without a motor speed reduction device such as a gear box. The motor is typically pulsed on for between 10 and 1000 milliseconds (ms), depending on the motor RPM, length of the cord and the rate of rotation desired for the mobile. The assembly that includes the motor, printed circuit board, circuitry to run the motor, batteries, and may or may not also include the flexible elastic cord or multiple strands of filaments attached to the motor shaft, is called the free standing module. The standard methods of detecting rotation are relatively expensive and require relatively high power, which would shorten the battery life. The present invention uses a novel mechanical switch, which requires very little power and is inexpensive.
Another object of this invention is to provide inexpensive craft kits that include multiple free standing modules along with pre-cut, scored nets made of card stock. For example, the five Platonic solids, whose faces are congruent regular polygons and whose polyhedral angles are all congruent, & symmetrical, can be easily formed from nets. The Archimedean solids are somewhat more complex but also have high symmetry and they too can be formed into pleasing three-dimensional objects from nets as can many other solids. These nets can either be decorated by the crafter or can be supplied as pre-decorated. The free standing modules are designed to attach to the nets prior to being formed into three-dimensional objects. Also, the nets can be de-constructed for battery replacement.
The dimensions and volume of the free standing module are small compared to the volume of a typical three-inch diameter Christmas ornament. Since the craft kits are already supplied with ornaments supplied as nets, the amount of retail store shelf and warehouse space to be saved is significant.
Another objective of the invention is to provide inexpensive craft kits that include foam shapes that have been hollowed out such that the free standing modules, that are also included in the kit, can be fitted into them. The crafter can decorate the foam shapes by gluing, pinning or painting decorations on the outside of the foam shape.
Also, an objective of the invention is to provide mobiles with stands such that the mobile can be placed on a desk, table or other flat surface. Hangers will be provided for the mobile to be mounted to a wall or ceiling.
The invention also provides mobiles wherein the free standing module is a part of the hanger or stand rather than being mounted inside the mobile. It also includes a means for activating the free standing module at times specified by the user for lengths of times specified by the user as well as for some pre-determined number of cycles when motion is detected. Also, it can include a means for detecting light such that the free standing module will be activated for some pre-determined number of cycles only when the ambient light level is greater than a predetermined level, or a specific sound or ambient sound level is detected.
Another feature of the invention is to provide mobiles wherein the free standing module is a part of the hanger or stand rather than being mounted inside the mobile and includes a means for detecting sound such that the free standing module will be activated for some pre-determined number of cycles by a specific sound or ambient sound level.
Yet another objective of the invention is to provide mobiles wherein the free standing module is a part of said hanger or stand rather than being mounted inside the mobile and includes a means for detecting light, sound, motion, specified times or any combination thereof such that the free standing module will be activated for some pre-determined number of cycles.
DETAIL DESCRIPTIONS OF THE INVENTIONAll illustrations of the drawings are for the purpose of describing selected versions of the present invention and are not intended to limit the scope of the present invention.
Referring to
In reference to
The production tolerance of inexpensive components of the type used in many consumer products such as this can vary by a range of ±10% or more. In addition most of the components have additional temperature dependence. That is, in addition to manufacturing tolerances, the tolerances can vary with changes in ambient temperature and possibly changes in battery voltage as battery life decreases. Thus, the performance can vary significantly over the manufacturing component tolerances and ambient temperature conditions. However, motor pulse excitations can be made to occur after any arbitrary whole or whole plus fractional number of resonant periods and that the percentage of randomization of said periods can be either greater or lesser than ten percent, which is used only for illustrative purposes, therefore making it possible to keep the peak values close to the more desirable amplitude of 1.4 of any N 19 turns.
Referring to
It is also found that for properly chosen motor drive duration and string wind up the mobile can be caused to rotate at a desired maximum speed. Further, the interval during which it unwinds and winds up again before reversing direction and beginning again may be controlled by the proper combination of the string elastic properties and length as well as the rotational inertia of the mobile itself. In reference to Appendix I, while the desired rotation speed and reversal interval may be found by experimentation with different string material properties, diameters and lengths to match the inertia of the particular mobile, it is nevertheless instructive to review the equations of motion controlling this interaction. The equations given are approximate but sufficient since the oscillations have only some small loss and decay slowly.
Appendix I—Basic Equations for Lossless Torsional Pendulum:Elastic cord 204 provides a rotation torque when it is twisted T in proportion to its elastic shear modulus G, torsional moment of inertia J, length L, and angle of twist α as follows:
T=GJα/L.
Therefore the torsional stiffness K, which is the torque per angle of twist, is given by:
K=T/α=GJ/L
At the same time, the frequency f of the rotational wind up and reversal is given by:
f=ω/2π=√(K/I)/2π.
where I is the rotational moment of inertia of the hanging object, the mobile 213, about its vertical axis of rotation. Then, by substituting the full expression for torsional stiffness K we find that the rotational frequency of reversing is given by:
f=√(GJ/IL)/2π or expressed in radians/sec:
ω=2πf=√(GJ/IL).
Since the motion is periodic, an angle as a function of time θ(t) may be written as:
θ(t)=Θ sin(ωt)
where Θ is the maximum wind up and the rotational speed is given by:
θ′(t)=Θω cos(ωt)
where Θω is the peak rotational speed. Again substituting from above, the peak speed is given by:
Θω=Θ√(GJ/IL).
Thus by choosing the string elastic constant G, its diameter d (J=πd̂4/32), its length L and the mobile's rotational inertia I, the frequency of repeating may be controlled and finally by also choosing the initial wind up Θ, the peak initial speed may also be controlled once the frequency is set by:
√(GJ/IL).
Note that since the peak speed depends on the peak rotation angle Θ, as the oscillations decay and the peak rotation angle decreases, the peak speed drops in proportion. The motor 213 may rewind the string 204 before the rotations die out to re-energize the mobile 213 as desired.
The mobile 213 can be analyzed as a torsion pendulum. Referring again to Appendix I, since the losses are low, the resulting system is highly resonant, with its resonant frequency given by formulae in Appendix I. In reference to Appendix II, the ratio Q of resonant frequency to bandwidth, of practical mobiles can be quite high, limited only by the low frictional and hysteretic losses. As a result, the amplitude of oscillation is very sensitive to the period between successive motor activations.
Appendix II—Effect of Frictional Losses:The effect of air resistance can be modeled as linearly proportional to the rotational speed of the mobile. The equation of motion becomes:
r″=−pr−qr′
where r is the angular displacement, constant p reflects the torsional stiffness of the elastic cord divided by the rotational moment of inertia, and constant q reflects the effect of air resistance.
Assuming q is small compared with p, the resulting second order system has a pole at:
−q/2+i*√(p).
Thus the resonant frequency is √(p) and the 3 dB bandwidth is q. The resulting Q (quality factor) is √(p)/q. The real part of the pole, −q/2, is the time constant for decay of the angular displacement. The period of oscillation is determined by the imaginary part of the pole, and is:
2*pi/√(p).
The rotational amplitude after one cycle is:
e(−q*pi/sqrt(p)), or:
e(−pi/Q).
So the amplitude decay per cycle depends only on Q. For the simulations used, p=1.0 (plus or minus 21%), and q=0.07 (plus or minus 10%). The resulting resonant frequency is 1.0 (plus or minus 10%). The rotational amplitude after one cycle is approximately eighty percent. The Q (quality factor) of the simulated resonance is 14.3. This Q matches the empirically measured Q of a sample mobile, and thus the simulations accurately reflect real performance.
In reference to
The peak amplitude with psudo-random excitation curve 100 shows the peak amplitude in the case of pseudo-random excitation, and the peak amplitude with a fixed period excitation curve 101 shows the peak 11 amplitude in the case of fixed interval excitation. The peak amplitude with psudo-random excitation curve 100 shows significantly improved performance, in that the peak amplitude is roughly constant (3.3N to 3.7N) regardless of the actual resonant frequency that occurs after all the manufacturing and ambient variables are accounted for. The peak amplitude with a fixed period excitation curve 101 shows the undesired result of a widely varying peak amplitude (2.0 to 3.8N), obtained by used of fixed interval excitation. The RMS amplitude with psudo-random excitation curve 102 shows the root mean square amplitude in the case of pseudo-random excitation is roughly constant (1.01N to 1.04N), as desired. The RMS amplitude with fixed period excitation curve 103 shows the root mean square amplitude in the case of fixed period excitation, which varies undesirably (0.7N to 1.9N).
There have also been other applications for randomized excitation of resonant systems has been used to advantage in other contexts. Other prior art include U.S. Pat. Nos. 6,144,172, 2,300,946, and 6,076,772. Randomized excitations of resonant systems have even led to the collapse of bridges.
In reference to
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Also, it is an objective of this invention to show how a non-elastic filament or cord can be used to accomplish the same oscillatory performance as can be accomplished with an elastomeric cord or string. Again referring to
The rotation reverses direction repeatedly, each time as the metal arm 203 pivots connecting the input pin 305 to either the input Vcc pin 303 or the ground pin 304, or to neither as the metal arm 203 can move between said pins without coming into contact with either of them. The micro-controller can recognize each of these three conditions, and can thereby determine the direction of rotation and accurately infer the angular position of outer shell 201 with respect to rigid anchor point 212. From this data, the micro-controller can determine the resonant frequency and can then compute the desired time interval before re-activating the motor 202.
In reference to
Due to variations in the diameter of the elastic cord 204, in the mechanical properties of an elastomer, and the effects and variations caused by ambient temperature on the mechanical and electrical performance, the resonant frequency 214 of identically manufactured mobiles will vary. In addition, the resonant frequency 214 will change as the mobile ages and the air temperature changes. Furthermore, if the length of the elastic cord 204 is changed after installation, the resonant frequency will also change.
If the period of time between motor activations is constant, it needs to be longer than the time it takes for the oscillations of the mobile 213 to be fully damped out. However, this means that for a large part of the time between motor activations, the mobile will be rotating at undesirably slow and uninteresting rates. However, if the time period between motor activations occurs before the rotational oscillations have damped out and if the period of time between motor activations is constant, the motor activations may deliver rotations to the elastic cord 204. These rotations may be either additive or subtractive to any residual rotation existing in the cord, depending on the time between motor activations. However, it is important to note that the elastic cord could break due to excessive twist as the resonance builds up. At a minimum, the speed of rotation would be so high as to be undesirable.
One of the many objectives of this invention is to provide a randomized period between motor activations that will result in consistent performance from mobile to mobile, as desired. The best result is obtained when the range of periods is selected to reflect the range of resonant frequencies 214, taking into account the manufacturing tolerance, temperature range, and aging characteristics.
The preferred embodiment is a pseudo-random sequence that has been selected so that its short-term frequency spectrum is spread uniformly across the range of resonant frequencies, without any peaks in narrow sub-bands. In particular, the motor activation periods should not have short patterns that repeat, which would overexcite mobiles with matching resonant frequencies and under excite mobiles with different resonant frequencies.
Another objective of this invention is to provide consistent rotational performance by the inclusion of a method to measure the resonant frequency of the system, and a micro-controller to perform analysis and calculate the optimal period between motor activations and accurately infer the angular position.
There are multiple choices for such a sensor. Photo sensors can be used to detect ambient room light changes as the mobile rotates. Alternatively, an inertial sensing integrated circuit can be used to detect the centrifugal force while the mobile rotates. Also, an electronic compass integrated circuit can be used to detect changes in direction of the Earth's magnetic field as the mobile rotates.
These standard methods of detecting rotation are relatively expensive and require relatively high power, shortening the battery life. The present invention uses a novel mechanical switch, which requires very little power, is inexpensive, and will be discussed later.
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It is an objective of this invention to provide a method wherein the mobile is only activated when it is suspended by its cord. This is particularly desirable for mobiles that are used seasonally, such as Christmas ornaments. More particularly, this is important when coin cells are used for the power source so that the ornament weight and size can be kept to a minimum. With the current invention, ornaments, which are considered to be a special case of mobile, eighty millimeters in diameter and weighing less than seventy grams which contain the batteries, electronic drive circuit, and motor therein have rotated continuously for four months on two LR44 coin cells. A typical LR44 coin cell will retain 80% of its power when stored for three to four years. Assuming that the ornaments would typically not be used for more than a month at Christmas, a set of batteries should last several seasons.
In reference to
In the present embodiment, a hollow spherical mobile 50 is made up of two plastic hemispheres that are snapped together along a seam 400. The hollow spherical mobile 50 is suspended by the elastic cord 204, which is attached to the table display hanger wire 55 by a cord attachment adaptor 61, which has a friction fit for a hanger wire 66 on one end and a flexible cord crimp 65 on the other end to connect the elastic cord 204 and the table display hanger wire 55.
In reference of
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The present invention can be mounted on the ceiling as well. Referring to
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Another objective of this invention to provide a free standing module that can be mounted inside a plurality of mobile designs that contain the elements necessary to cause said mobile to move.
Again, in reference to
In reference to
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In reference to
An advantage of the present invention is that use of the smaller batteries, which greatly reduce the weight and size of the invention. Therefore, the present invention can be suspended from delicate structures such as Christmas tree branches. Another advantage is that the self contained module can be placed inside a typical two and a half-inch diameter ornament so that the ornament can be suspended directly from the tree via the cord, which is part of the self contained module thus creating the illusion that the ornament is moving by itself.
An advantage of the present invention is that the smaller batteries greatly reduce the weight and size of the invention so that present invention can be suspended from delicate structures such as Christmas tree branches.
Another advantage is that the self-contained module can be placed inside a typical two and a half-inch diameter ornament so that the ornament can be suspended directly from the tree via the cord, which is part of the self-contained module thus creating the illusion that the ornament is moving by itself.
In reference to
Referring to
In reference to APPENDIX IV, there is a source code for the simplest version of operation, which is turning a motor on for a very short period of time out of a very long cycle. Acceptable results can be obtained with the designs shown herein with motor on times as short as fifty milliseconds and times between motor on times of at least five to six minutes. A range of motor on times between ten milliseconds and sixty seconds and motor off times between one minute and sixty minutes can be used. Generally speaking, the heavier the weight 70 suspended, the greater the moment of inertia, the longer the pulse on times must be and the longer the time between pulses can be. Other motor on pulse times and time between pulses are possible. As discussed earlier, these can be tailored to the specific performance requirement of whatever object is to be animated by this invention.
Appendix IV Software Code for Microprocessor:Twirlee.hex
(Executable Image Programmed into the Microcontroller)
:1000000025006400030A6400050A6600000C06006F
:10001000CF0C02008306350A010C3E007F00B300BE
:100020001F020307F400B400140213014307380A47
:10003000320C31007200070C2600F90C300004006D
:10004000F0021F0A230A04000400010C3E007F0096
:10005000B1001F020307F200B200120211014307B0
:100060001D0A6600820C3300370A7300B302740065
:040070000300050A7A
:021FFE00E70FEB
:00000001FF
File io.h
(Associates and Defines Input/Output Used by twirlee.c)
/* This file was generated automatically. Edit at your own risk. */
#ifdef TARGET_PROTOTYPE
/* Sample usage:
-
- B8(01010101)=85
- B16(10101010,01010101)=43605
- B32(10000000,11111111,10101010,01010101)=2164238933
*/
In reference to
When two filaments of a filament diameter 260 are twisted together, the double strand filament cylinder effective diameter 266 is the result, which is essentially still the diameter of cylinder 284. A pitch 285 is determined by angle theta 286 and the double strand filament cylinder effective diameter 266 of cylinder 284.
Again referring to
In reference to
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This can take from seconds to minutes depending on the length of the cord, diameter and stiffness of the cord, moment of inertia of any object suspended, internal friction of the cord and rubbing friction between cord filaments and the shape of the object. All of the above being the same, the more gross symmetry an object has around the rotating axis, the longer it will oscillate for a given number of initial twists. All of the above being the same, a symmetrical object with a smooth surface will oscillate longer than an identical object with a roughened surface for a given number of initial twists.
In reference to
In reference to
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Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.
Claims
1. A method for a moving display with a free standing module assembly comprises of the following steps:
- housing the free standing module assembly inside of a mobile;
- attaching one end of an elastic cord or a plurality of filaments to a cord adaptor;
- attaching the cord adaptor to a motor;
- traversing the elastic cord or the plurality of filaments inside of a free standing mobile assembly by way of a mobile clear opening in the mobile;
- wherein the free standing module assembly comprises of a free standing module, which houses a power source and the motor, which help to create movement for the mobile; and
- suspending an opposite end of the elastic cord or an opposite end of the plurality of filaments from a table display assembly, a ceiling mount assembly, or a wall mount assembly.
2. A method for a moving display with the free standing module only comprises of the following steps:
- housing the free standing module in an enclosure;
- wherein the free standing module includes the power source and the motor, which help to create movement of the mobile;
- traversing the elastic cord or the plurality of filaments through the keeper shaft extension and an enclosure clear opening in the enclosure; and
- mounting the free standing enclosure;
- connecting one end of the elastic cord or the plurality of filaments to the cord adaptor;
- wherein the cord adaptor is attached to the motor;
- connecting the opposite end of the elastic cord or the opposite end of the plurality of filaments to the mobile; and
- suspending the mobile by the opposite end of the elastic cord or the opposite end of the plurality of filaments.
3. A method for oscillation of the mobile with the elastic cord comprises of the following steps:
- powering of the motor with a plurality of batteries;
- twisting of the elastic cord repeatedly by the motor at a plurality of pre-determined intervals of time or for a continuous period of time;
- wherein each pre-determined interval of time is longer than time of periodic, quick twisting by the motor;
- storing of energy in the elastic cord by twisting of the elastic cord;
- wherein the twisting for the plurality of pre-determined intervals of time is activated when triggered when a pre-determined sound level sound occurs or the twisting is activated for the plurality of pre-determined intervals of time when a pre-determined minimum ambient light level is detected or when a pre-determined rate of change of ambient light level is detected; and
- oscillating of the mobile.
4. The method for oscillation of the mobile with the elastic cord as claimed in claim 3 comprises of the following steps:
- randomizing the plurality of pre-determined intervals of time; and
- preventing the over-twisting of the elastic cord through the randomization of the plurality of pre-determined intervals of time.
5. A method for random oscillation of the mobile with the plurality of filaments comprises of the following steps:
- powering of the motor with a plurality of batteries;
- twisting the plurality of filaments quickly with the motor at the plurality of pre-determined intervals of time or for a continuous period of time;
- wherein each pre-determined interval of time is longer than time of periodic, quick twisting by the motor;
- raising of the mobile against gravity through twisting of the plurality of filaments;
- shortening length of the plurality of filaments by raising of the mobile;
- storing of energy through twisting of the plurality of filaments and raising of the mobile;
- wherein the twisting for the plurality of pre-determined intervals of time is activated when triggered when a pre-determined sound level sound occurs or the twisting is activated for the plurality of pre-determined intervals of time when a pre-determined minimum ambient light level is detected or when a pre-determined rate of change of light level is detected; and
- oscillating of the mobile.
6. The method for oscillation of the mobile with the plurality of filaments as claimed in claim 5 comprises of the following steps:
- randomizing the plurality of pre-determined intervals of time; and
- preventing the over-twisting of the plurality of filaments through the randomization of the plurality of pre-determined intervals of time.
7. A method to detect change in direction of torque to calculate resonant frequency of an oscillating mobile with the elastic cord or the plurality of filaments comprises of the following steps:
- housing of the printed circuit board assembly in an outer shell;
- wherein the printed circuit board assembly comprises of the motor, a printed circuit board motor shaft, a metal arm, a printed circuit board, a tab, a cord, and a cross beam;
- suspending of the outer shell by the elastic cord or the plurality of filaments;
- pivoting of the metal arm in the printed circuit board assembly;
- wherein the metal arm moves with respect to the printed circuit board as direction of torque changes;
- detecting of the metal arm movement with respect to printed circuit board;
- tracking of number of pulses from clock of known frequency between detection of metal arm movements;
- converting pulse count into resonant frequency by a microprocessor; and
- controlling operation of the motor with resonant frequency.
8. The method to detect change in direction of torque to calculate resonant frequency of an oscillating mobile with the elastic cord or the plurality of filaments as claimed in claim 7 comprises of the following steps:
- engaging of the notch by the tab;
- contacting electrically of the metal arm with an input pin;
- wherein motion of the metal arm is restricted by the input Vcc pin and the ground pin;
- rotating of the outer shell until the elastic cord or the plurality of filaments is reverse twisted; and
- driving of the outer shell by the motor and the metal arm.
9. A method for rotating a heavily suspended mobile comprises of the following steps:
- housing a thrust bearing assembly in a cavity of the heavily suspended mobile;
- driving a thrust bearing motor shaft by a planetary gear assembly; and
- wherein the planetary gear assembly is driven by a thrust bearing motor.
10. A method for activating the mobile by suspension comprises of the following steps:
- attaching one end of the elastic cord or the plurality of filaments to the cord adaptor;
- wherein the cord adaptor is connected to the motor shaft of the free standing mobile assembly; and
- suspending the free standing module assembly by the elastic cord or the plurality of filaments.
Type: Application
Filed: Dec 30, 2011
Publication Date: Jul 5, 2012
Inventor: David M. HADDEN (Los Altos, CA)
Application Number: 13/341,393
International Classification: A63H 33/00 (20060101);