Note: Descriptions are shown in the official language in which they were submitted.
13~9702
CAMERA AND OTHER INSTR~MENT SUPPORT STAND
Field of the Invention
The present invention relates to tripods and
other stands for supporting cameras, transits, and other
instruments, and also to instrument supporting heads
which support the instruments on the stand.
Description of the Prior Art
Prior art instrument support stands, and in
particular tripods used in cinematographic applications
to support motion picture cameras, suffer from a number
of disadvantages.
Tripods used for this purpose frequently are
used to support cameras weighing anywhere from 15 to 100
pounds or more, and which can cost in excess of
$15,000. When a heavy camera is mounted to a typical
prior art tripod device, the assembly is extremely
top-heavy. As a result, the camera is not stably
supported, particularly when used in heavy cross winds
and on uneven terrain. Naturally, the user of this
expensive equipment becomes very nervous and worried
about the equipment under these conditions, which can
detract from the user's concentration and result in less
than ideal photographs.
In an attempt to overcome this instability, it
is not unusual for equipment operators to suspend heavy
weights between the legs of a tripod. This is done to
lower the center of gravity of the tripod and to thereby
add a greater degree of stability to the tripod during
use. However, the need to add weights for stability
adds to the difficulty of setting up the tripod and
moving it from one location to another. Also, under
adverse conditions, a camera operator will sometimes
have one or more individuals hold on to a tripod to help
anchor the tripod in place during use. This prevents
these individuals from performing other more productive
tasks.
~k
Moreover, cameras of this type typically are
used with long relatively heavy lenses. These lenses
contribute to the instability of a tripod supported
camera, particularly if the center of gravity of the
camera and lens is not positioned directly over the
center of the tripod. Moreover, if the camera happens
to flop forward, the center of gravity may be shifted
enough to tip the entire tripod over.
In addition to instability problems, existing
tripods are typically relatively difficult and time
consuming to set up, especially in cramped quarters or
where a flat supporting surface is not available. This
limits the number of setups of the tripod from which
photographs may be taken during a limited photograph
shooting time. Also, more than one person is required
to set up many types of prior art tripod devices.
Furthermore, with many tripod devices, the legs must be
adjusted to level a camera. This can be extremely
difficult, particularly where the legs include spreaders
~o that must be loosened and then retightened in order to
adjust the position of the legs.
Another significant drawback of known tripods
used in cinematography is their lack of rigidity. They
simply tend to deflect too much during use, thereby
interfering with a photographer's work.
Camera supporting heads for mounting to tripods
are also known. In addition, many heads of this type
permit panning of the camera about a vertical axis, as
well as tilting of the camera about a horizontal axis.
In a first known type of head, fluid in the head passes
through an orifice or by a blade to apply drag to the
head movement. However, with these types of devices, it
is extremely difficult to accelerate or deccelerate the
head, particularly where a smooth change of panning or
tilting movement is desired. In addition, heads having
friction mechanisms for applying drag to the panning and
f ~
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tilting movement are also known. However, heads of this
type known to the inventors provide an uneven feel to a
photographer when the photographer shifts from a panning
to a tilting motion. In particular, the camera on such
heads tend to "square out" when shifted from a panning
to a tilting movement, rather than making a gradual or
smooth transition. In addition, friction heads of this
type are typically either operable at their initial drag
condition or are locked in place with a separate locking
mechanism. That is, it is extremely difficult to set
these heads to a drag which is between the initial drag
and locked conditions as very little adjustment
capabilities exist.
It is also desirable to provide a mechanically
simple and cost effective camera supporting tripod which
eli\~;~ates
_rtb-~e~es struts, spreaders and the like which can
interfere with a photographer's work. Moreover, known
prior art tripods lack versatility for use in the widely
variable environmental conditions frequently encountered
by photographers who work outside of a photographic
studio. In addition, prior art tripods and heads are
typically designed for cameras of a given narrow range
of weight. Therefore, different tripods are used when a
photographer plans to use different size and weight
cameras.
U.S. Patent 875,034 of Wright exemplifies these
prior art devices. In Wright, a platform is mounted to
three legs of fixed length. A short stub shaft has a
lower ball positioned in a socket on the platform. The
ball is locked in place by mechanically clamping the
socket against the ball. A camera is mounted to a plate
carried at the upper end of the stub shaft. A pair of
bubble levels are mounted to this upper plate for use in
leveling the camera after the tripod is set up. Devices
such as shown in Wright suffer from a number of the
above drawbacks, including an apparent lack of rigidity
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and inability to stably support a relatively heavy
camera.
British Patent 1,377,897 of O'Conner is still
another example of a prior art tripod device. In
O'Conner, three legs of fixed length are pivoted to a
lower body portion of this device. Hydraulic struts are
used to adjust the position of the legs. In this
device, a single valve is opened to enable the legs to
be adjusted to various positions relative to the body of
the apparatus. The valve is then closed to lock the
hydraulic struts and thus the legs in position. A
center shaft of adjustable length extends upwardly in a
fixed direction from the lower body portion. Wedge
blocks and pins are used to lock telescoping sections
forming the shaft to set the shaft length. The O'Conner
device also suffers from a number of the above
drawbacks. In particular, the tripod of this patent
would not appear to be highly stable in crosswinds or
when used on substantially uneven terrain. In addition,
the device of this patent lacks versatility. For
example, the positions of the various legs are
understood to be adjusted in unison and the legs are of
a fixed length.
U.S. Patent 3,795,378 of Clark discloses a
tripod having a platform which is adjusted to a desired
level or angle by delivering hydraulic fluid to
telescoping legs of the device. Hydraulic fluid is
supplied in unison to the legs to adjust their relative
lengths and setup the tripod. The tripod of Clark has a
relatively bulky hydraulic fluid reservoir positioned
between the tripod legs where it can hamper a
photographer's movements. Also, this device appears to
lack the rigidity and stability desired in tripod
applications.
In addition, attachments for tripod heads are
known which enable a user's torso to control tilting and
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panning movement of the head. A device of this type is
shown in ~.S. Patent 4,177,967 of Marchus.
In view of the above, a need exists for an
improved instrument supporting stand, such as of the
tripod type. A need also exists for an improved
instrument support head for such a stand.
Summary of the Invention
The present invention comprises a support stand
and head for an instrument such as a camera, which
includes the following features either alone or in
combination with one another:
(a) An upright instrument supporting body, at
least three legs, leg pivot means each associated with a
respective one of the legs for coupling the legs to the
body for pivoting about respective generally horizontal
pivot axes to various positions relative to the body,
and manually actuated hydraulic leg position locking
means for selectively and independently locking each of
these legs in position relative to the body;
(b) The body having a hip to which the legs
are mounted and an elongated upright shaft with a lower
end formed in a ball and mounted to the hip for
universal tilting movement on the hip within limits, and
manually actuated hydraulic hip locking means for
selectively locking the ball and thereby the shaft
against tilting movement relative to the hip;
(c) The legs being adjustable as to length and
the apparatus including manually actuated hydraulic leg
length locking means for selectively and independently
releasably holding each of the legs in any position of
adjustment as to length;
(d) The center shaft being adjustable as to
length and the apparatus including manually actuated
hydraulic means for releasably holding the shaft in
adjustment as to length;
(e) A camera or instrument mounting head
:~3~ ~7~3~,
supported by the upper end of the shaft, the head
including panning mounting means for coupling the head
to the shaft for panning motion about a generally
: vertical axis, the head including an instrument support
member and tilt mounting means for mounting the
instrument support member to the head for tilting
movement about a generally horizontal tilt pivot axis,
the panning mounting means and tilt mounting means each
comprising manually adjustable friction brake means for
varying the drag on the panning and tilting movement,
the friction brake means each including plural friction
engagement means of a material having substantially
equal coefficients of dynamic and static friction, the
friction engagement means being positioned for
frictional engagement, and means for varying the force
with which the friction engagement means engage one
~ another to vary the drag;
: (f) The friction brake means each including
means for modulating the force applied to the friction
engagement means;
(g) The head being configured to support the
:~ instrument carrying support member at a position spaced
from the upper end of the shaft, thereby providing a
substantial gap between the support member and shaft,
this gap accommodating a user's hands for camera and
other instrument adjustments during use of the tripod;
(h) The legs being configured as a tripod and
pivotal relative to the hip through an arc of
approximately 180 degrees;
(i) ~ach leg having a wall bounding a pivot
pin receiving opening through an upper end thereof and
oriented such that the pivot pin receiving opening has a
- substantially horizontal axis, the hip including plural
pivot pin means, one such pivot pin means being
associated with each leg and received in the pivot pin
receiving opening of the associated leg, the pivot pin
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means comprising means for pivoting each of the legs to
the hip for pivoting about respective substantially
horizontal pivot axes, each pivot pin means being
selectively expandable in outside dimension to
releasably grip the wall of the associated pivot pin
receiving opening and thereby lock the legs against
movement relative to the hip, and leg position locking
means comprising means for selectively expanding the
pivot pin means in outside dimension to lock the legs
against movement relative to the hip;
(j) Each leg including a first tubular leg
section and a second tubular leg section telescopingly
received by the first leg section, the second leg
section including a leg length locking portion
expandable in outside dimension for gripping the first
leg section to lock the two leg sections against
relative movement and thereby releasably hold the length
of the leg, and leg length locking means for selectively
and independently expanding the leg length locking
portions in outside dimension to lock the first and
second leg sections against relative movement;
(k) The center shaft including a first tubular
section and a second tubular section telescopingly
received by the first section, the second section
including expandable shaft locking means for expanding
in outside dimension to releasably grip the first shaft
section and restrain the shaft sections from further
relative movement, thereby releasably holding the center
shaft at a fixed length;
(1) A cap or foot for the lower end of each
leg having a body with a hemispherical lower portion,
means for connecting the body to the end of the leg, the
body being of material with a durometer which is in the
range of from 40 to 90, the body having a coefficient of
friction which is similar to that of natural rubber or
neoprene, and the hemispherical portion of the body
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having a diameter which is approximately from one to two
times the cross-sectional dimension of the leg to which
the body is mounted; and/or
(m) The cap more specifically having a body
which is generally spherical, having a durometer from 60
to 65, and a diameter which is from 1.25 to 1.35 times
the cross-sectional dimension of the leg to which the
body is mounted.
It is accordingly an overall object of the
present invention to provide an improved support for a
camera or other instrument.
A still further object of the invention is to
provide an improved instrument support head, capable of
panning and tilting movement, for supporting a camera or
other instrument on a tripod or other stand.
Another object of the present invention is to
provide an improved tripod for cameras and other
instruments.
Still another object of the present invention
is to provide a highly stable and rigid camera support;
Another object of the present invention is to
provide a tripod which is easy and quick to setup.
A further object of the present invention is to
provide a tripod which is extremely versatile for use in
a wide variety of applications.
Still another object of the present invention
is to provide a tripod which can be collapsed to a
relatively small size for easy transportation and
storage.
Another object of the present invention is to
provide a tripod which is usable by individuals of
widely varying heights.
Still another object of the present invention
is to provide a tripod for stabling supporting cameras
and other instruments of a wide range in weight.
It another object of the present invention to
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provide a camera head which provides a uniform feel to a
photographer as it is panned and tilted.
A further object of the present invention is to
provide a camera head which is capable of applying
variable resistance or drag to panning and tilting
movement.
A still further object of the present invention
is to provide a tripod which is durable and yet is
relatively mechanically simple for the versatility
provided by the device.
These and other features, objects and
advantages of the present invention will become apparent
with reference to the following description and drawings.
Brief Description of the Drawings
Fig. 1 is a front top perspective view of an
instrument supporting stand and head in accordance with
the present invention;
Fig. 2 is a perspective view of the apparatus
of Fig. 1, shown in a fully collapsed state;
Fig. 3 is a perspective view of the apparatus
of Fig. 1, shown in one position of adjustment;
Fig. 4 is a perspective view of the apparatus
of Fig. 1, shown .in a further position of adjustment;
Fig. 5 is a perspective view of the apparatus
of Fig. 1, shown in still another position of adjustment;
Fig. 6 is a perspective view of the instrument
supporting head portion of the apparatus of Fig. 1, with
a camera shown in dashed lines, and with a guidance
apparatus coupled to the head;
Fig. 7 is a sectional view of the portion of
the head used to couple the camera and guidance
apparatus to the head;
Fig. 8 is a vertical sectional view taken
through panning and tilting friction brake mechanisms
included within the head of the Fig. 1 apparatus;
Fig. 9 is a vertical sectional view taken
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through the hip portion of the apparatus of Fig. 1:
Fig. 10 is a vertical sectional view through
the upper end of a leg of the apparatus of Fig. 1,
showing a leg position locking mechanism used in the
apparatus together with a portion of a leg length
locking mechanism included therein;
Fig. 11 is a perspective view of an expansion
sleeve included in the leg position locking mechanism of
Fig. 10, and in other locking mechanisms of the
apparatus, for locking purposes;
Fig. 12 is a vertical sectional view of a lower
portion of a leg of the apparatus of Fig. 1, showing a
portion of a leg length locking mechanism included in
the leg; and
Fig. 13 is a vertical sectional view through a
portion of the upright center shaft of the apparatus of
Fig. 1, showing a portion of the shaft locking mechanism
included therein.
Detailed Description of Preferred Embodiment
Overall Description
With reference to Figs. 1 through 5, the
illustrated support stand in accordance with the present
invention comprises a tripod 10. This tripod is
suitable for supporting a multitude of types of
instruments, including transits and cameras. Although
not to be construed as a limitation, the description
proceeds with reference to a camera supporting
application. In this case, a camera supporting head 12
is mounted to the tripod 10.
The tripod 10 includes a body having an upright
center shaft 14 with its lower end 16 mounted to a hip
18 of the body for universal tilting movement on the hip
within limits. This tilting movement is indicated
schematically by arrows 20 in Fig. 1. A hip locking
means is provided for selectively locking the shaft 14
against tilting movement relative to the hip. As
~ 3 ~ J
explained in greater detail below, the preferred form of
this locking means comprises a manually actuated
hydraulic hip locking mechanism. This mechanism is
controlled by rotating a knob 21 in one direction to
selectively release the shaft 14 for tilting movement
and by rotating the knob in the opposite direction to
lock the shaft against such movement.
The shaft 14 is comprised of first and second
telescoping tubular shaft sections 24, 26. These
sections are capable of relative sliding movement as
indicated by arrow 28 to adjust the length of the shaft
14 and thus the height of head 12. A shaft length
locking mechanism is provided for releasably holding
shaft sections 24, 26 against relative movement to
thereby hold the shaft in adjustment as to length. In
the preferred form, this shaft length locking mechanism
comprises a manually actuated hydraulic means, described
below, for releasably holding the shaft in adjustment.
A knob 30 is rotated as required to selectively lock and
unlock the shaft sections 24, 26.
The tripod 10 includes three legs 40, 42 and
44. These legs are adjustably mounted to the hip 18 so
as to project from the hip in various directions (such
as shown in Figs. 3-5) to stably support the body and so
as to permit collapsing of the legs against the shaft 14
(such as shown in Fig. 2). In the illustrated
embodiment, legs 40, 42 and 44 are pivoted to hip 18 for
pivoting about respective horizontal axes in directions
generally indicated by arrows 46, 48 and 50.
A leg position locking means is provided for
selectively locking each of the legs in position and
against movement relative to the hip. In the
illustrated form, this leg position locking means
comprises means for independently locking each of the
legs against movement relative to the hip. In
particular, such means may comprise manually actuated
SS~7~
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hydraulic leg position locking means for locking the
respective legs in any position of adjustment relative
to the hip. Knobs 60 and 62 are rotated to selectively
lock and unlock the legs 40, 42 in position. A similar
knob, not shown, is rotated to lock the leg 4~ in
place. The details of this form of leg position locking
me~hanism are described below.
The legs 40, 42 and 44 are also adjustable in
length and a mechanism is provided for releasably
lo holding the legs in adjustment. Arrows 64, ~6 and 68
indicate the leg length adjustment feature. The leg
length locking mechanism, in the illustrated embodiment,
comprises manually actuated hydraulic leg length locking
means for selectively and independently releasably
holding each of the legs in any position of adjustment
as to length. Knobs 70, 72 and 74 are rotated to
control the leg length locking mechanisms. These
mechanisms are operable as explained below to lock and
release the legs for length adjustment.
The instrument supporting head 12 includes a
panning mounting means 80 for coupling the head 12 to
shaft 14 for panning motion about the shaft axis, which
is typically in a generally vertical orientation. The
head also includes an instrument support member,
indicated generally at 81 and described in detail
below. A tilt mounting means 82 mounts the instrument
support member to the head for tilting movement about a
generally horizontal tilt pivot axis. In Fig. 7,
panning movement is indicated by arrow 84 and the
tilting movement is indicated by arrow 86. A lever arm
88, with a handle 89, is coupled to the head 12 by a
coupling mechanism 90 as explained below. Lever 88 may
be shifted by a photographer to provide leverage for
controlling panning and tilting motion of the head 12.
As explained in greater detail below in
connection with the operation of the apparatus, a tripod
~3~ `d
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and head assembly in accordance with the present
invention is extremely versatile. In addition, legs 40,
42 and 44 are capable of pivoting through an arc of
approximately 180 degrees. AS a result, the legs may be
pivoted against shaft 14, as shown in Fig. 2, and then
locked in place to provide a compact easily storable and
transportable apparatus. In addition, shaft sections 24
and 26 may be collapsed as well and locked in place as
shown in this fig~lre. Moreover, with reference to Figs.
3-5, the legs may be adjusted to any position and length
for use in virtually any terrain.
In addition, although not shown in these
figures, a level sensor may be mounted to shaft 14
adjacent head 12. When such a level sensing apparatus
is used, the legs 40, 42 and 44 are adjusted in length
to position shaft 14 in a generally vertical
orientation. The hip lock mechanism is then released,
by loosening knob 21, to permit tilting of the center
shaft 14 until such time as the level sensor indicates
that the shaft 14 is vertical. Knob 21 is then
tightened to lock shaft 14 against further tilting.
With the level sensor positioned adjacent head 12, and
given the substantial length of elongated shaft 14, the
shaft may be pivoted in any direction through a5 substantial angle to accomplish this leveling.
Camera Supporting Head
The camera or instrument support head 12 is
best seen in Figs. 1, 6, 7 and 8 and will be described
with reference to these figures. As shown in Fig. 1,
the instrument support structure 81 is spaced from the
upper end of shaft 14 and also from the panning mounting
means 80 to provide a substantial gap therebetween. A
user of the tripod can insert his or her hands into the
gap for access to camera and other instrument adjustment
mechanisms. This makes head 12 more convenient to use.
In the illustrated head 12, a tilt mechanism supporting
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arm 100 is angled upwardly and outwardly from the
panning mounting mechanism 80. Arm 100 carries the tilt
mounting mechanism 82. A similar arm 102 extends
upwardly and inwardly from the tilt mounting mechanism.
Arm 102 terminates in a camera supporting base plate
104, which is shown positioned above shaft 14 in Figs.
and 6.
As best seen in Fig. 7, base plate 104 has an
upper planar instrument supporting surface 106 for
lO slidably receiving a camera mounting plate 108 of
trapezoidal cross sectlon. Plate 108 has a camera
mounting bolt 110 for connection to a mounting aperature
in a camera 112. As shown in Fig. 7, plate 104 is
formed with an overhanging lip 114 contoured to overlie
15 and engage a side edge of mounting plate 108. A locking
bar 115 has a tapered edge 116 contoured for engaging
the opposite side edge of mounting plate 108. Locking
bar 115 threadedly receives the upper end of a bolt 117,
which extends through a portion of the base plate 104.
20 ~olt 117 is connected at its lower end to a knob 118.
Knob 118 is rotated in one direction to clamp locking
bar 115 against the edge of mounting plate 108 to secure
plate 108 to plate 104 and thus to the head. Rotation
of knob 118 in the opposite direction releases bar 115
25 and the plates 104, 108. The underside of mounting
plate 108 is provided with a detent opening for
receiving a spring biased detent 122 when mounting plate
108 is slid on mountlng surface 106 to its mounted
position as shown in Figs. 1, 6 and 7.
Typically, mounting plate 108 is slid free of
base plate 104. When these elements are separated, the
mounting plate is then secured to the underside of
camera 112 by bolt 110. Thereafter, the mounting plate
is slid on surface 106 until the detent 122 engages
35 detent opening 120. Locking bar 115 is then tightened
to securely mount camera 112 to the instrument
:~ 3 ~3 ~
supportiny head 12. In addition, mounting plate 108 is
locked to base plate 104 in a positon such that the
center of the camera is tilted by tilt mechanism 82 in a
plane which contains the axis of shaft 14. This adds
stability to the supported camera because an even side
to side weight distribution is provided.
With further reference to Fig. 7, the base
plate is provided with a transversely extending opening
126 through which lever 88 is inserted. Opening 126
extends through collet receiving projections 128, 130
which project outwardly from the base plate 104. The
outer ends of these projections, one being shown in Fig.
7, terminate in an annular tapered surface 132. Collets
134. 136 are threaded onto the respective projections
128, 130. Collets 134 is provided with an annular
wedging surface which engages the surface 132. As
collet 134 is tightened, the projection 128 is clamped
against the lever 88 to releasably secure the lever in
place. Collet 136 is similarly constructed. Collets
134, 136 are also provided with openings 140 spaced
about their perimeters. Rods, such as 142, are inserted
into these openings and used to tighten the collets to
secure the lever 88 in place.
A torso engageable guide 144, such as disclosed
in ~.S. Patent 4,177,967 of Marchus, may be mounted by a
mounting mechanism 146 to the lever 88 in place of the
handle 89 shown in Fig. 1. The height of the tripod 10
is adjusted to position the upper portion of the guide
144 at the upper torso or shoulder level of an
individual using the tripod. The guide is also adjusted
toward and away from the user until it is comfortably
positioned to engage the user's shoulder with the lower
portion of the guide extending between the user's upper
arm and upper torso. Mechanism 146 is then tightened to
hold guide 144 in adjustment. The portion of the guide
144 extending between the upper arm and upper torso is
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conveniently gripped by pressing the upper arm and the
guide 144 against the upper torso. When this is done,
as the user's upper torso is moved, the head 12 is also
moved in a graceful manner in accordance with the fluid
movements of the individual user. Rapid, discontinuous
and exaggerated movements of the head 12 are prevented
since the upper body of the user does not move in this
manner. Furthermore, control of the head by the upper
torso frees the user's hands for other purposes, such as
advancing film and adjusting the camera.
The internal construction of the illustrated
panning and tilting mechanisms 80, 82 is best seen in
Fig. 8. Since each of these mechanisms 80, 82 is
identical, only the panning mechanism 80 will be
described in detail. However, like elements of
mechanisms 80 and 82 are designated with like numbers.
The panning mechanism 80 includes a central
block 150 of circular cross section. Block 150 has an
enlarged upper portion 152 and a lower neck portion 154
inserted into a socket 156 at the upper end of tubular
shaft section 26. Block 150 is fastened to the shaft
section at neck 154. The upper end of shaft section 26
is of reduced outside dimension to provide a shoulder
158 which supports an annular collar 160. This collar
is of L-shaped cross section with vertical and
horizontal legs 162, 164. Leg 162 is sized larger in
outside cross-sectional dimension than block 152 so as
to provide an annular shelf 164 as shown in Fig. 8. An
annular bearing 166 is included in this assembly.
Bearing 166 has inner races 168 which abut shelf 164 and
surround the block section 152. Arm 100 has a base
section or mount 170 with a circular bore 172. The
lower portion of mount 170 is positioned above collar
leg 164 and is coupled to the outer race 174 of bearing
166. With this construction, arm 100, and the remaining
portions of the instrument supporting head 12, are
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pivotal about the axis of the tripod shaft as indicated
by arrow 84 in Fig. 8. Mount 170 has an annular lip 186
which abuts the upper end of bearinq race 174. Annular
wedging rings 180, 182 are received within respective
grooves of mount 170 and block section 152. Wedge ring
182 compresses inner bearing races 168 while wedge
ring 180 preloads the outer bearing race 174 against
lip 186.
The panning mechanism 80 also includes a
manually adjustable friction brake 190 for varying the
drag on panning movement. In the illustrated
embodiment, the friction brake includes plural friction
engagement means such as annular disk pads 192, 194.
These disk pads 192, 194 are mounted respectively to an
upper portion of mount 170 and to the block section
152. The disks 192, 194 are stacked as shown so that
respective upper and lower surfaces of the disks abut
one another. In operation, these disks are pressed
together with varying degrees of force to vary the drag
on panning movement.
The friction brake 190 shown in Fig. 8
includes a means for modulating the force applied to the
friction pads 192, 194. More specifically, an
externally threaded shaft 200 extends upwardly from the
upper end of block section 152. A pressure applying cap
202 is threaded onto shaft 200. This cap has a lower
bearing surface 204 which is shifted axially along shaft
200 toward and away from block section 152 as the cap
202 is rotated in respective opposite directions. A
friction pad engaging collar 206 surrounds block section
152. Collar 206 is slidable relative to this block
section 152 and also relative to the mount 170. The
illustrated force modulation means comprises an annular
wave spring washer 208 which rests on a step provided in
collar 206. Wave spring 208 is compressed as the
bearing surface 204 is moved toward the block section
152.
3 ~
This construction perrnits fine adjustment of
the drag on the panning movement. For example, cap 202
and wave spring 208 are typically designed so that the
cap can rotate substantially (Eor example, through two
complete revolutions) between an unbraked position and a
locked position. In the unbraked position, little or no
force is typically applied to the pads 192, 194.
However, this unbraked position, which is established by
the position of a retaining ring 210 on shaft 200, may
be set so that wave spring 208 is partially compressed
when the upper surface of cap 202 engages retainer 210.
In this case, a minimum drag exists. The magnitude of
this minimum drag depends upon the compression of wave
spring 208 in this state. In comparison, in the fully
locked state, bearing surface 204 abuts the upper end of
collar 206, for example as shown in connection with
locking mechanism 82 in Fig. 8, so that pads 192 and 194
tightly grip one another and lock the device against
panning movement. In the absence of such a force
modulating means, rotation of cup 202 through as little
as five degrees would shift the brake from an unlocked
to a locked state. This would not permit any reliable
degree of drag adjustment. Therefore, with this
construction, a user may easily adjust the drag to
panning movement over a wide range.
As also shown in Fig. 8, a removable decorative
cover 214 may be mounted to cap 202. In addition,
O-ring dust seals 216, 218 substantially seal the
braking mechanism 190 from the environment. A friction
button 218 of, for example, Nylon material, may be
mounted to shaft 200 for bearing against cap 202. This
button prevents the cap 202 from turning as the
instrument supporting head is panned.
As another important aspect of the friction
braking mechanism, in the preferred embodiment the disks
192 and 194 are made of a material with substantially
r¦ ~3 ~
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equal coefficients of static and dynamic friction.
Consequently, if panning or tilting motion is either
accelerated or decelerated, the drag remains
substantially constant and at the setting established by
the user. In addition, by using disk pads having
similar dynamic and static coefficients of friction in
both the panning and tilting mechanisms, smooth
transitions between panning and tilting are permitted.
That is, a user of the device can pan the instrument
supporting head and gradually tilt the head in a smooth
manner.
As a specific example, the disks 192, 194 may
be of a carbon-fiber reinforced composite material, such
as nylon 6/6 grade RCL-4536 material from LNP Thermo
Comp Corporation. This material is typically used in
bearings and is not known to the inventors to have been
used in friction brakes. Of course, any suitable
material having substantially equal coefficients of
static and dynamic friction would also have these
desirable characteristics.
It should be noted that the structural
components of the head, as well as of the tripod, are
typically of a rigid lightweight material, such as
aluminum.
Hip Locking Mechanism
One form of mechanism for locking shaft 14
against tilting movement relative to hip 18 is shown in
Fig. 9-
As shown in this figure, the shaft 14 includes
30 a lower stub shaft 240 which terminates in a ball 242.
Stub shaft 240 is threaded onto, and is thereby
connected to, the lower shaft section 24 at 244. The
hip 18 comprises a hip block having a upwardly opening
socket 246 formed therein and sized for loosely
35 receiving the ball 242. The curved lower surface 248 of
the ball rests against the upper correspondingly curved
2~
- 20 -
surface 250 of a movable hydraulic piston 252 positioned
within the hip. Piston 252 slides within a bore 260 of
the hip toward and away from the surface 248 of the
ball. A split annular ball retaining collar 254 is
retained within socket 246 by a retaining ring 256.
Collar 254 has a bearing surface 258 which abuts the
adjacent surface of ball 2fi2. With this construction,
the ball, and thus shaft 14, is universally mounted to
the hip 18 for tilting movement within limits defined by
the components of the hip. As a specific example, the
components as shown permit movement of the shaft through
an angle of approximately nineteen degrees in any
direction from vertical.
In the illustrated embodiment, a hydraulic
mechanism is provided for moving piston 252 to lock
shaft 14 in place. In connection with this mechanism, a
hydraulic fluid receiving chamber 264 is formed within
hip 218. This chamber communicates, by way of several
bleed openings to the exterior of the hip. These
openings are closed by bleed screws 266 and seals 268
and provide a means by which air and fluid may be
drained from the hydraulic fluid chamber 264 as it is
filled. Chamber 264 includes a minute gap or space 270
between an internal surface of the hip at the base of
bore 260 and the lower surface of piston 252. An
annular compressable spring 272 bears against the hip
and lower surface of the piston. This spring 272
comprises a means for preloading the hip piston 252
against the ball 242. Typically, approximately thirty
pounds of preload is applied. Thus preload prevents the
shaft 14 from loosely flopping from side to side when
hydraulic pressure is relieved in chamber 264. A
commercially available four lobed seal 274 is positioned
in an annular groove about the perimeter of piston 252
for sealing the space between the sides of the piston
and the bore 260.
~ f~r'r)~
- 21 -
A manually actuated hydraulic pump 280 is
provided for varying the hydraulic fluid pressure in
chamber 264 to force the piston 252 against ball 242 and
thereby lock shaft 14 against tilting movement relative
to the hip. The illustrated mechanism 280 includes an
externally threaded shaft 282 mounted to hip 18 and
projecting into an enlarged section 284 of hydraulic
chamber 264. A pressure control shaft 286 is threaded
onto shaft 282. The knob 21 is coupled to shaft 286, as
by a set screw 288, so that rotation of the knob 21
advances shaft 286 into or out of chamber section 234.
This varies the volume of the overall hydraulic chamber
264 and in turn varies the fluid pressure within the
chamber. A groove 290 is formed in the exterior surface
of shaft 282 to permit hydraulic fluid to flow between
chamber section 284 and the interior 292 of control
shaft 286 as knob 21 is turned.
The chamber section 284 is of a first diameter
as shown. The hip 18 also has an intermediate bore 300,
adjacent chamber section 284, which is of a greater
diameter than that of the chamber section. An outer
bore 302, of a greater diameter than intermediate bore
300, is included in the hip 18 adjacent to and extending
coaxially with the bore 300. An annular four lobed seal
304 is placed in bore 300 between a pair of rings 306,
308 for sealing hydraulic chamber section 284 against
leakage at this location. A dished or belleville washer
or spring is positioned in outer bore 302 against ring
308. A ring 312, also in outer bore 302, bears against
the dished washer and is retained in place by a retainer
314 coupled to the hip. A retalning ring 216 is mounted
to the surface of shaft 286 to prevent removal of the
shaft from the hip during use.
Dished washer 310 comprises one form of a fluid
accumulator means. That is, as fluid pressure increases
within hydraulic fluid chamber 264, spring 310 is
~3~ 32
- 22 -
eventually compressed because rings 300 and 308, as well
as seal 304, slide along shaft 286 toward this spring.
Consequently, excessive pressures in the hydraulic fluid
c~lamber 264 are prevented. In addition, the volume
displaced by shaft 286, before this shaft bottoms out on
shaft 282, is sized to control the maximum pressure in
the chamber 264. Typically, piston 252 is shifted only
about three to five thousandths of an inch to lock the
ball in place. In addition, typical maximum fluid
pressures within chamber 264 range from 700 to 1000
psi. These pressures are easily achieved within
hydraulic chamber 264 merely by manually turning knob
21.
Hip 18 includes an upwardly projecting flange
318 having an outwardly facing groove 320. An upper end
portion of stub shaft 240 is also provided with an
outwardly facing groove 322. A boot 324, of a resilient
flexible material such as neoprene, has a lower bead 326
positioned within groove 320 and an upper bead 328
positioned within groove 322. These beads are secured
within these grooves to hold the boot in place. Boot
324 seals the hip assembly from dust, rain and the
like. Yet, boot 324 permits the desired tilting
movement of shaft 14 relative to the hip.
Leg Position Locking Mechanism
With reference to Figs. 10 and 11, the leg
position locking mechanism for leg 40 will next be
described. A similar locking mechanism is provided for
each of the other legs 42, 44.
In general, the leg 40 has a wall 340 which
bounds a pin receiving opening through an upper end of
the leg. This pin receiving opening is generally
circular in cross-section and oriented to have a
substantially horizontal axis. A pivot pin means, one
form being indicated at 342, is positioned in the pivot
pin receiving opening 340. This pivot pin means pivots
~ rl3~ ~
- 23 -
the leg 40 to hip 18 for pivoting about a horizontal
pivot axis. The pivot pin means 342 is selectively
expandable in outside dimension to releasably grip the
wall 340 and thereby lock the leg 40 against movement
relative to the hip. Means, such as manually actuated
hydraulic leg position locking meansr are included in
this assembly for expanding the pivot pin means to
accomplish this locking action.
In the illustrated embodiment, hip 18 is
provided with a pair of spaced apart ear flanges 344,
346 which receive the upper end of leg 40 therebetween
as shown in Fig. lO. Flanges 344, 346 have respective
openings 348, 350 which are sized and oriented to be
aligned with opening 340 when leg 40 is in position. A
pivot pin assembly 352 is inserted through these
openings to pivot the leg 40 to the flanges 344 and 346
and thereby to hip 18. Pivot pin assembly 352 includes
a pin body 354 with a hydraulic chamber 356 which
communicates through passageways 358, 360 with the
exterior of the pin body. An annular bladder 362 of a
resilient material, such as neoprene, surrounds the pin
body and seals the hydraulic chamber 356 at the exterior
of the pin body. The bladder has enlarged lip end
sealing portions 364, 366, each of a double O-ring
configuration. These end portions 364, 366 are
positioned in respective spaced apart annular grooves
368, 370 in the exterior surface of pin body 354. A
thin cylindrical bendable split reinforcing sleeve 372,
for example of polyethelene, surrounds the bladder 362.
This sleeve protects the bladder during installation and
use.
First and second cylindrical or annular wall
gripping sleeves 380, 382 are positioned to surround the
bladder 362. These sleeves have exterior surfaces which
contact the wall 340 of the pin receiving opening. As
shown in Fig. ll, sleeve 380 is provided with plural
~ ~ ~3 ~
- 24 -
longitudinally extending spaced apart slits, some being
numbered 384, from one end 38h thereof. These slits
define fingers 387, therebetween, which overlie the
reinforcing sleeve 372 and thus the bladder.
A manually actuated hydraulic pump mechanism
390, which may be of the same form as mechanism 280
described above, is operable to selectively increase the
hydraulic fluid pressure in chamber 356. When this
happens, bladder 362 expands and forces the fingers 387
into gripping engagement with wall 340 so as to lock the
leg 40 against pivoting movement relative to the hip.
Since mechanism 390 is like mechanism 280, it will not
be described in detail. However, corresponding elements
are provided with corresponding numbers. Again, as
described above, a dished washer 310 acts as a fluid
accumulator in this pump mechanism. Typically, when
hydraulic fluid pressure increases to from about fifty
to sixty psi, the fingers 386 are shifted into gripping
engagement with wall 340. When fully locked, hydraulic
pressures in chamber 356 of from 700 to 1000 psi are
common.
Lock screws 400, 402 secure the pin body 354 to
flanges 344, 346 and prevent relative rotation between
the pin assembly 352 and hip. Lock screws 404, 406 also
lock the respective wall gripping sleeves 380, 382 to
the pin body so that these sleeves do not rotate when
the assembly is locked. O-ring dust seals 408, 410
provide environmental protection for the assembly.
This form of leg position locking mechanism is
convenient and easy to use. In addition, when locking
is complete, the tripod structure is extremely rigid.
Leg Length and Shaft Length Locking Mechanisms
Referring to Figs. 10, 12 and 13, mechanisms
for locking shaft 14 in adjustment as to length and also
for locking the legs 40, 42 and 44 as to length are
shown.
D: f
~ ore specifically, each leg, illustrated in
connection with leg 40, includes a first lower and outer
tubular leg section 420 and a second inner tubular leg
section 422 which is telescopingly received by the first
leg section. The inner leg section 422 is threadedly
connected at 424 to an upper end portion 426 of the leg
assembly. A dust seal 428, which may be of plastic or
other suitable material, is mounted to leg section 420
for sliding against leg section 422 to prevent dirt from
entering the space between these sections.
The inner leg section 422 includes a leg length
locking mechanism expandable in outside dimension for
gripping the outer leg section to lock the two leg
sections against relative movement. When this is
accomplished, the leg sections are no longer slidable
relative to one another and the length of the leg is
established. In the form shown in Fig. 12t this leg
length locking means 429 is similar in construction to
the locking pin means 342 described above. However,
instead of a pin body 354, the mechanism includes a leg
locking body 430 as shown. Because mechanism 429 is
like the previously described mechanism 342,
corresponding elements are numbered with corresponding
numbers and will not be described in detail. It should
be noted, however, that relative rotation between leg
sections 420 and 422 is not a significant problem.
Therefore, only the lower most gripping sleeve 380 is
secured to the leg locking body 430 by lock screws.
Hydraulic fluid is delivered to the leg length
locking mechanism by a manually actuated hydraulic pump
432 as shown in Fig. 10. This pump is controlled by
knob 70 and is of the same construction as the pump 390
described above. Therefore, corresponding elements of
this pump are numbered with corresponding numbers and
will not be described in detail.
A hydraulic fluid conducting tube 434
~ 3~f~7
- 26 -
communicates from hydraulic fluid chamber 356 to the
remainder of this chamber which is included within leg
length locking body 430 (Fig. 12). As shown in Fig. 12,
a pair of four lobed annular seals 440, 442 surround the
upper and lower ends of tube 434 for sealing purposes.
Respective retaining rings 444, 446 are clamped against
seals 440, 442 to complete the seal.
With this construction, and also in part
because of the length of the leg length locking body
430, the legs are extremely rigid even when locked in
their positions of furthest extension.
The locking mechanism 459 for shaft 14 is shown
in Fig. 13. This mechanism is virtually identical to
the leg length locking mechanism 429 except that a shaft
length locking body 460, like leg length locking body
430, is used. An identical hydraulic fluid pumping
mechanism (not shown), but like pump 432, is used to
apply hydraulic fluid pressure to the shaft length
locking mechanism to lock the shaft in the desired
length-
To provide a more complete description of theillustrated embodiment, but not as a limitation to the
scope of the invention, the length of the legs when
fully collapsed is approximately twenty-eight inches.
When fully extended, the legs are about forty-five
inches long. These dimensions are from the center line
of the wall opening 340 to the base of a cap 470. In
addition, the shaft length, measured from the center of
ball 242 to the top of mounting plate 108 ranges from
about thirty to forty inches, depending upon whether the
shaft is contracted or extended. With the legs extended
as described, the tripod assumes a highly stable
giraffe-like stance.
Moreover, with the legs angled at about
thirty-seven degrees relative to hip 18, the overall
height of the tripod and head varies from about fifty
- 27 -
inches (with the legs and center shaft retracted) to
about seventy-five inches (with the legs and center
shaft fully extended). These measurements are taken
from a level floor engaged by leg caps ~70 to the top of
mounting plate 108. Therefore, the tripod may be placed
in an extremely stable condition for use by individual
of various heights.
In addition, the entire tripod and head is only
about thirty-two inches long when totally collapsed as
shown in Fig. 2.
Leg Caps
The lower or distal ends of the legs are each
provided with a cap 470 (Figs. 1 and 12). These caps
greatly enhance the performance of the tripod because
they are specially designed to engage both irregular and
regular surfaces to provide a stable contact for the
tripod legs. Moreover, stability is provided when the
legs, such as leg 44 in Fig. 4, are extended in a
substantially horizontal orientation. In addition, the
tripod has been tested with one, and even two, of the
legs leaning against a wall and found to be extremely
stable in this orientation as well.
Referring again to Fig. 13, the cap has a body
472 with a lower portion which is generally
hemispherical. A means is provided for connecting the
upper portion of the body to the end of the leg. In
this illustrated form, cap 470 has an opening 474 sized
for receiving the end of tubular leg section 420. In
addition, the illustrated cap is spherical so that the
upper portion of the cap provides a bearing surface when
in contact with the ground or other support surface.
The cap body 472 is preferably of a material
with a durometer which is in the range of from 40 to 90,
and more preferably in the range of from 60 to 65. In
addition, the cap 472 has a coefficient of friction
which is similar to that of natural rubber or neoprene.
7 ~ 2
- 28
Moreover, the cap has a diameter which is approximately
within the range of from one to two times the diameter
of the leg section to which the cap is mounted. In the
preferred form, the cap has a diameter which is from
1.25 to 1.35 times the cross-sectional dimension of the
connected leg section 420.
With caps of this configuration, as well as
with the hydraulic locking mechanisms described above,
the tripod of the invention is extremely stable and
rigid under widely varying conditions of use. However,
this rigidity and stability is achieved to a high degree
even without this specific form of caps.
Operation
With reference to Figs. 1 through 5, a tripod
and head assembly in accordance with the present
invention is typically transported in its collapsed
state shown in Fig. 2.
When the location for photographic shooting is
reached, the tripod is set up, such as shown in Fig. 1
with a camera attached to the camera mounting plate 108
(see Fig. 6) and carried by the instrument supporting
head.
Prior to attaching the camera in place, the
legs 40, 42 and 44 are individually extended or
retracted until the hip 18 is somewhat level. However,
precise leveling of hip 18 is not required. Typically,
for greatest stability, the legs are spread in an
extremely wide giraffe-like stance, with shaft 14
extending upwardly. In addition, because of the
rigidity of the locking mechanisms and the tripod
assembly itself, the legs may be extended in a
horizontal orientation and still rigidly support a
mounted camera. For example, in nature photography it
is sometimes desirable for the photographer to dig a pit
in which to hide while waiting for birds or other
animals to approach. With a tripod of this invention,
7 s~
- 29 -
the legs ~ay be spread across the pit opening in a
horizontal orientation. Once positioned, the tripod
center shaft 14 may be adjusted to a height where only a
slight movement o~ the photographer is required to bring
the photographer's eyes to the level o~ the camera
optics. Consequently, the photographer need not stand
or jump out of a pit to take photographs. Any such
movement would risk scaring away the animals or birds.
continuing with the description, once the legs
are positioned, the shaft is adjusted for proper height
and locked into place by turning knob 30 to control the
shaft length locking mechanism. In addition, the hip
locking mechanism is released, by turning knob 21, to
permit tilting of shaft 14 to level the instrument
supporting head 12 with respect to the horizon. Again,
a leveling mechanism (not shown) may be mounted to the
shaft for this purpose. The shat may be tilted to
other orientations if required to obtain particular
shots.
Once the tripod is setup, the camera is mounted
to mounting plate 108 and then positioned on the
instrument supporting head 12 and locked in place. The
gap between plate 104 and panning mechanism 80 provides
easy access to knob 118 for shifting locking bar 116
into locking engagement with the plate 108 (Fig. 7).
The panning and tilting mechanism 80, 82 are
adjusted, as previously exp]ained, to establish the
desired drag on the panning and tilting movement. Once
the camera is set, photography can commence.
This tripod and instrument supporting head is
so riglu and stable that the camera may be panned
through 360 degrees without loss of stability. In
addition, the tilt drag may be easily varied to balance,
or be slightly in excess of, the tilting force exerted
by the camera on the instrument support head 12.
Consequently, the photographer can walk away from from
.3 ~
- 30 -
the tripod without fear of the camera falling over and
tipping the assembly. Yet, by exerting the slightest
force on lever 88, the camera can be tilted as required
during shooting.
In addition, the tripod and head of the present
invention can stably support cameras weighing from
fifteen to one hundred pounds or more.
Having illustrated and described the principles
of our invention with reference to one preferred
embodiment, it should be apparent to those persons
skilled in the art that such invention may be modified
in arrangement and detail without departing from such
principles. We claim as our invention all such
modifications as come within the true spirit and scope
of the following claims.
