Method and means for producing motion in water beds

Motion is departed to the water in water beds by periodically lifting a region of the lower surface of the water bed mattress, said region being contained somewhere within the outer margins of the water bed. A water motion that is more uniform and more acceptable in practical applications is provided by lifting a region at least one of whose margins is not parallel with the plane of any of the sides of the water bed mattress. In a preferred embodiment, it is a triangular section of the bottom of the water bed that is lifted, and the lifting is accomplished by tilting that triangular section upwardly toward the upper wall of the apparatus and by accomplishing that tilting from the apex of the triangular region. In a refinement of the action, a means is provided for adjusting the lifting action in frequency or degree to achieve a relationship with the natural resonant frequency of water movement that produces a pleasant bed motion.

This invention relates to improvements in methods and means for producing 
motion in water beds. 
BACKGROUND OF THE INVENTION 
The water bed, in which the mattress is a water filled, pliant container, 
has gained wide acceptance. It has become a standard, readily available 
alternative to the spring mattress bed. The popularity of the water bed is 
based partly upon the fact that the water mattress, by Pascal's law, 
provides a more uniform supporting reaction over a wider area of the 
user's body. The popularity of the water filled mattress can also be 
attributed to the reaction offered by such a mattress to a user's 
movements. Upon being placed in motion, the water in a water bed is 
displaced such that it behaves like a resonant system comprised of a mass 
and spring interconnected in a low friction combination. While the 
oscillatory frequency of water movement depends upon the volume being 
moved, and while the development of standing waves in the mattress depends 
upon a number of variables, including the point at which input 
displacement of water is applied, the oscillatory frequency and the low 
order harmonics of that frequency are such that oscillatory motion through 
several cycles is experienced in response to many of the ordinary 
movements of the water bed user. 
Not everyone wants a bed that imparts a feeling of movement. However, it is 
logical to assume that those who choose water beds over conventional 
mattresses, including very soft conventional mattresses, are looking for 
that kind of movement. It is also apparent that it is impossible for the 
water bed designer to find a design which will provide optimum results for 
all users. The size, and the weight, and even the number of users is 
unknown, and may differ from one case to another. Whatever the design in 
terms of length, width and thickness of the mattress, and in terms of 
volume of water, and the inclusion or absence of inner support structures 
and other variables, some user movement may be expected to produce water 
movement that induces a less than pleasant feeling for the user or for a 
bed partner. Also, in the ordinary water bed, water movement does not 
occur except as a reaction to user movement. That has been viewed as a 
deficiency, and some attempts have been made to provide more water 
movement by applying vibrators to the mattresses. Notwithstanding such 
attempts, it appears that the prior art does not include a satisfactory 
method or structure for imparting adequate movement to the water in a 
water bed in the absence of user movement. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide a means by which some motion 
can be imparted by the water in a water bed mattress independently of user 
movement in a way that imparts a pleasant and, for some, a euphoric 
feeling. 
Another object of the invention is to provide a means in which the water is 
moved repetitively in a way that simulates a continuing motion similar to 
wave action. 
Another object of the invention is to provide such a wave action in a 
selected degree that is relatively uniform regardless of the position 
assumed by bed users, but which will change in some degree as the user 
changes position to the end that the feeling of motion experienced by the 
user can be changed merely by changing position. 
Another object of the invention is to provide a structure that can produce 
such results and which is easily installed and simple to operate. 
These and other objects and advantages of the invention, which will become 
apparent upon reading of the description below, are realized in part by 
the provision of a platform of such size as to accommodate the lower wall 
of a water bed mattress arranged so that the mattress will lie generally 
horizontally. An inner region of the area of that platform is mounted for 
movement in a direction to lift part of the lower wall of the water bed 
mattress when the mattress is disposed on that platform. That is combined 
with means for lifting and lowering that region of the platform on a 
periodic basis. In the preferred arrangement, the lifting and lowering is 
accomplished at a uniform frequency. In one form of the invention, the 
platform is formed with a cutout or opening in a central region within its 
margin. A member disposed in or over that opening is movable in a 
direction that includes a vertical component whereby to lift and lower the 
mattress wall that overlies the opening. The direction and the velocity 
and the magnitude of water flow within the mattress is a function of the 
degree in which the mattress wall is lifted, the frequency of the lifting 
and lowering action, and the position of the region that is lifted. Those 
variables are also a function of the shape of the portion of the mattress 
that is lifted. If a region of the lower mattress wall that extends 
entirely from one side of the mattress to the other is lifted, the 
resulting water movement, and the feeling imparted to the bed user, is 
substantially different than the feeling that results when the region 
being lifted is less wide than the mattress. For a reason that is not 
clear, the motion that is imparted to the bed induces what is generally 
considered to be a better feeling when the region of the mattress wall 
that is lifted has a side lying in a plane that is not parallel to any of 
the side walls of the mattress. In that circumstance, water is driven both 
lengthwise and sideways within the mattress as that region is alternately 
lifted and lowered. The best mode thus far discovered for practicing the 
invention includes lifting and lowering a region of the lower wall of the 
mattress that includes a side that extends at an angle to the mattress 
sides and in which the lifting is accomplished by tilting up that region 
so that one edge of the region remains in the plane of the lower mattress 
wall while the opposite edges are lifted to a level above that plane. The 
best form yet devised employs a generally horizontally platform on which 
the water mattress rests. A triangular region of that platform is cut out 
at a position that would normally underlie a user's legs. The apex of the 
triangular cutout is at the head side of the platform. The base of the 
triangular section is generally parallel to the head and foot edge of the 
bed, or at least is perpendicular to the direction to which the user is 
expected to lie on the bed. A triangular member, which may comprise the 
cutout portion of the platform, is disposed in the cutout and is hinged to 
the platform at its apex. A means is provided for lifting and lowering the 
triangular insert so that it tilts upwardly from the plane of the platform 
to a position in which the base of the triangular insert is above that 
platform. The triangular portion is lifted by any suitable means, such, 
for example, as an electric motor coupled to the element that is to be 
tilted by an eccentric mechanism. 
It is possible to find a frequency and a degree of tilting that is 
generally acceptable to most users. However, it has been discovered, and 
it is a feature of the invention, that the motion can be adjusted to make 
a single design suitable for a wide range of water bed sizes, and of user 
sizes, by altering either the frequency of rotation or the degree of 
lifting of the displaceable elements. That is a fortuitous finding because 
it means that adjustment can be accomplished simply by adjusting the 
degree of eccentricity in the connection between the motive means and the 
movable element. In view of that, an alternating current motor may be 
selected as the motive means, notwithstanding that such motors tend to 
operate at constant speeds. It is to be understood, however, that 
adjustability can be provided without changing the degree at which the 
lower wall of the mattress is displaced by providing a means for 
accomplishing lifting and lowering at different frequencies.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The water bed selected for illustration in FIG. 1 has a simple design, but, 
except for the inclusion of the invention, has a construction that is 
representative of most water beds. It comprises a water filled mattress 10 
that is contained within a box-like frame 12 having a headboard 14 fixed 
to its head end. The box frame is supported by a supporting structure 16 
which is barely visible at the side of the bed. 
The construction of the box frame can be understood by comparison of FIGS. 
1 and 2. The frame has four side walls. The wall at the foot end of the 
bed is designated 18. The wall at the head end of the bed is designated 
20. In FIG. 1, the near side wall is numbered 22. Just a small portion of 
the far side wall 24 is visible at the extreme left in FIG. 1. Those four 
sides stand vertically, and they are attached to a flat platform 26 which 
is visible in FIG. 2. The lower margins of the frame walls extend below 
the lower surface of the platform 26 and hide from view, except from 
below, supporting members that interconnect the side walls and the 
platform at the margins of the wall. Three of those supporting members are 
visible in FIG. 2 where they are numbered 30, 32 and 34, respectively. The 
member 30 is employed to reinforce the connection of the foot end wall 18 
to the platform. 
Member 34 is in the interconnection of the platform 26 with the head wall 
20, and the longitudinally extending member 32 supports the 
interconnection of the platform 26 with the side far wall 24. 
The mattress 10 is a water filled, pliant container. Its outside dimensions 
correspond generally to the overall dimensions of a conventional spring 
mattress. The body of water within the mattress is sufficiently heavy so 
that it is customary to support the platform 26 on which the mattress 
rests with a separate supporting structure. The structure shown in the 
drawings is a representative one. It is formed by four side walls 
interconnected to form a rectangle somewhat less long and less wide than 
the platform 26 which it supports. In this case, the supporting structure 
16 is formed by a far side wall 38 which is visible in FIG. 2 and a near 
side wall 40 which is visible in FIG. 1. Both side walls are 
interconnected by a head end wall 42, a foot end wall 44, and an 
intermediate cross wall 46, all of which are visible in FIG. 2. 
Thus far described, the water bed shown in FIGS. 1 and 2 is conventional. 
However, it differs in that a triangular section of the platform 26 has 
been cut away. That triangular section is shown in top view in FIG. 3. It 
has the general shape of an isosceles triangle whose base is parallel with 
the head end and the foot end of the mattress 10. In the case of 
mattresses of other shapes, that triangular section would be arranged so 
that the base would extend in the direction generally perpendicular to the 
length of a user of the bed. The apex of the section begins near the 
center of the bed, and the cutout extends to the foot end of the bed so 
that it is positioned below that part of the mattress that would 
ordinarily support a user's legs. The drawing is arranged to indicate that 
the cutout, in this preferred embodiment, is located midway across the 
width of the bed. 
The wall at the foot end of the cutout has been designated 48, and one of 
the side walls of the cutout is designated 50. The other side wall is 
designated 52. It will be apparent that the walls 50 and 52 extend at an 
angle to the side walls of the frame 12 and to the side walls of the 
mattress 10. Stated another way, the margins 50 and 52 lie in planes that 
are not parallel to the plane containing any of the side walls of the 
frame. 
A means is provided by which a region of the lower portion of the mattress 
10 can be lifted and lowered. In this preferred embodiment, that means is 
the triangular lifting member 54. In its lowered position, it fits within 
the cutout formed by walls 48, 50 and 52, and, indeed, it may comprise a 
portion of the platform 26 that was cut away to form the cutout. At its 
apex end, the lifting element 54 has pivotal connection to the platform 26 
by a hinge 56. In FIGS. 2 and 4, the lifting element 54 is shown tilted up 
from the plane of the platform 26, but it will be apparent that the 
mechanism by which that tilting is accomplished is capable of lowering the 
lifting member 54 so that it lies entirely within the cutout of the 
platform 26 and is parallel with the platform. In this particular 
embodiment, a stop 60, shown in FIG. 4, is fastened to the underside of 
the platform 26 and extends across part of the cutout. It operates to 
limit downward movement of the lifting member 54 to a position parallel 
with the platform 26. That is not essential for two reasons. First, the 
invention is not limited to a lifting and lowering motion in which the 
lowering of the bottom wall of the mattress 10 is limited to the 
horizontal position. The invention may be practiced by lowering the 
lifting member 54 below the level of the platform 26. Secondly, the 
preferred drive mechanism illustrated in the drawings serves to limit the 
amount of upward movement and of downward movement of the lifting member 
54. That lifting mechanism comprises an arm 62 the lower end of which is 
journalled to a shaft 64 as shown in FIG. 5. The end of that shaft is 
threaded into an opening in the outer face of a drive disc 66. The disc is 
mounted, at its central axis, upon the output shaft 68 of a reduction gear 
drive set 72 as shown in FIG. 2. The shaft 64 and the disc 66 combine to 
form a crank. As best shown in FIG. 4, the face of the disc 66 is provided 
with several openings in which the shaft 64 may be threaded. Each of those 
openings has a different distance from the center axis of the drive disc 
66 whereby an adjustment of the length of the crank arm is possible. 
In addition to the lower portion which is journalled to shaft 64 in FIG. 5, 
the lower part of arm 62 is internally threaded to receive an externally 
threaded extension rod 76 the upper end of which is fitted with a head, or 
transversely oriented disc, 78. That disc is trapped in a resilient 
coupling element comprising two blocks of resilient material numbered 80 
and 82, respectively. The lower block has a central opening to accommodate 
arm extension 76, and the adjoining faces of the two blocks are cut away 
to accommodate the head, or disc, 78. The two blocks are held together by 
a bracket 84 which is generally U-shaped and has sidewardly extending 
extensions at its upper arms. Those extensions are bolted to the underside 
of the lifting element 54 by a pair of bolts 86 and 88. When the motor is 
powered electrically by power applied through box 90, as shown in FIG. 4, 
its output shaft rotates a reduction gear set in the unit 70. The output 
of that reduction gear set is rotation of shaft 68 and hence the crank 
formed by shaft 64 and disc 66. Rotation of the crank drives the arm 62 up 
and down and the arm acts through the coupling element to drive the 
lifting element 54 up and down. 
If a direct current motor is employed at motor 72, motor speed and the 
frequency of operation of the lifting element 54 is easily adjusted. 
However, as previously explained, that is not essential. It is desirable 
that the input movement that results in water movement occur at a 
frequency near, but not at, the natural resonant frequency of water 
movement, or a sub-multiple of that frequency. But what that resonant 
frequency is is determined largely by the motion producing mechanism 
itself. It is entirely satisfactory to select an input frequency in the 
range of one to five seconds or more, and to adjust the degree of movement 
of the lifting element 54 to achieve whatever reflected wave action 
provides the most pleasant feeling. 
While the triangular form of motion input element provides what is 
considered to be the best motion, that form is not the only one that is 
useful in the invention. It is advantageous to use an element whose sides 
are not parallel with the sides of the mattress so that there is a 
sideward component to the water motion. That does two things. It 
diminishes the possibility that the user will occupy a postion and have a 
wait that results in the development of large standing waves. In addition 
to that, it provides a gentle multiple direction motion which is not 
likely to become monotonous. The use of a triangular form in which the 
base of the triangle is parallel with the head and foot ends of the 
mattress serves to combine sideways motion with endwise motion of the 
water to the end that the resultant motion is uniform across the entire 
length and width of the bed. 
It will also be apprent to the artisan that it is not essential that there 
be a cutout in the supporting platform. The element that does the lifting 
can be mounted above the platform and then driven through the platform. 
Moreover, it is not essential that that lifting element be one that tilts. 
Variations of that kind provide a new and beneficial action, although the 
preferred form is the one shown in the drawing. 
Although we have shown and described certain specific embodiments of our 
invention, we are fully aware that many modifications thereof are 
possible. Our invention, therefore, is not to be restricted except insofar 
as is necessitated by the prior art.