 |
Description  |
|
|
This invention relates to a stabilized zoom binocular in which a single
cardan joint simultaneously stabilizes stereoscopic eye paths. The
stabilized unit is ideally adapted for the placement of zoom optics.
Provision is made for a pulsed optical circuit having a stabilizer
torquing through electromagnetic force.
SUMMARY OF THE PRIOR ART
Stabilized binoculars previously had problems in three major areas. First,
the usable optical paths formerly were routed around the stabilizing
element in bulky and interfering optical paths. Second, stabilizing
elements that impart movement to the optical train equal to and opposite
from ambient accidental vibration (such as from a tremulous human hand)
have either been gyroscopically stabilized, fluidly stabilized, or
inertially stabilized. Finally, prior art stabilized binoculars have an
overall configuration which has been awkward for a viewer to use. No
attempt has been made to optimize the overall instrument size, shape, and
mass distribution to the convenience of the viewer. Viewers wearing
spectacles have not been able to see the full apparent field of view; to
see that full field, the glasses have had to be removed, so that the
pupils of the eyes could be closer to the oculars.
With regard to the difficulties of optical configuration, there exists a
class of prior art stabilizers that are monobinocular. Typically, they
include one objective with two eyepieces. True stereoscopic vision never
results. An example of such a device is the stabilized zoom optical device
U.S. Pat. No. 3,468,596, issued Sept. 23, 1969, to L. W. Alvarez, one of
the inventors herein.
In STABILIZED BINOCULAR U.S. Pat. No. 3,915,550, issued Oct. 28, 1975, to
William E. Humphrey, an optical path is disclosed for utilization to a
two-sided fluid stabilizer. Moreover, the binocular exit pupil includes a
central aperture common to Cassegrainian instruments.
With regard to stabilizers, gyroscopes include not only large mass but also
precession mechanics to compensate their movement in space relative to
desired lens or mirror movement in space. While fluid stabilized systems
are advantageous, they present some problems. For example, an optical
wedge is usually generated in off-axes positions. Moreover, a fluid
stabilized system in which the fluid is used as a refracting element
changes viscosity and refraction with temperature changes. Additionally,
the fluid itself imparts mass. Finally, the ultimate stabilization
produced gives a swimming-type stabilization to an image, which is hard to
adjust. In situations where magnification is being constantly changed--as
in zoom optics--this swimming effect can be unacceptable.
Prior art inertial stabilizers have been subject to "stiction." It will be
remembered that before the stabilizer undergoes any motion at all, the
static coefficient of friction of the system must be overcome, which has
produced an unacceptable jerk as a result of "stiction" present. This jerk
is repeated each time the system is in a static position. Moreover, wide
panning angles have required at least some centering by mechanical caging,
which results in a destruction of long-term viewing continuity.
The overall configuration of such prior art binocular stabilizers has been
difficult. Typically, the binoculars are hard to hold, since they have
relatively large masses protruding outwardly in front of the viewer. Since
the viewer must support these masses, arm fatigue usually results.
Moreover, where the instrument undergoes panning, problems occur when an
instrument held in front of a viewer is pivoted. When the viewer pivots,
the stabilized binocular tries to pivot about its center of gravity. Such
an instrument held at a distance from the viewer has an increased moment
of inertia, which increases as the square of the distance from the pivot
of the viewer. The result is that both objects have a natural tendency to
pivot in opposite directions about their own centers of gravity. Where
high power stabilization is occurring, even a tendency of both objects to
pivot in opposite directions is unacceptable.
As extremely relevant prior art, attention is directed to Humphrey U.S.
Pat. No. 3,475,073, entitled ACCIDENTAL MOTION COMPENSATED BY TRIPLE
REFLECTION and issued Oct. 28, 1969, which discloses stabilization by
triple reflection. Moreover, and as pertinent to the disclosure herein at
column 9, the use of zoom optics is suggested. The difficulties outlined
above in generating a stabilized binocular are not addressed in the
Humphrey patent.
As additional and extremely relevant prior art, attention is directed to
Humphrey U.S. Pat. No. 3,756,686 entitled SERVO-INTEGRATING STABILIZER and
issued Sept. 14, 1973. This patent relates generically to the method of
stabilization of the optical elements here used but does not suggest or
set forth the specifics of the invention herein.
SUMMARY OF THE INVENTION
A stabilized binocular using a single cardan joint and stabilized
triple-reflecting compensator (such as that in Humphrey U.S. Pat. No.
3,475,073) having three reflecting surfaces for each binocular path is
disclosed. Each of the binocular paths is in convergent light from an
objective to and through gimbaled stabilizer assembly to a primary focus
that is stabilized with respect to the case. The triple-reflecting
compensator for each path has three reflecting surfaces disposed to
reflect light in the manner corresponding to a single plane mirror at an
effective mirroring plane with a displacement between the incident and
reflected light beams. The compensator remains stabilized with respect to
inertial space, while the instrument undergoes accidental angular motion.
The reflecting property of the compensator brings the image back to the
same place on the case despite the accidental angular motion. The
displacing function of the compensator enables the image to be displaced
to a location where the image does not interfere with the incoming light
path. This image is then processed by conventional field optics.
In the preferred embodiment, a second displacing and reflecting element
affixed to the case relays the light path downwardly and below the
objective through which the light entered the instrument. The light ends
up moving in a direction approximately parallel to the direction it had
when it entered the objective lens aperture. Thereafter, the light is
passed through a mechanically or optically compensated zoom system, which
relays and reinverts the image as in a terrestrial telescope. The ten
combined mirrors of the moving compensator and case-affixed relay system
have no net effect on either image inversion or image parity.
Consequently, light emerging from either of the parallel zoom systems can
be brought upwardly or downwardly to a convenient side-by-side viewing
position, for necessary interoccular spacing adjustment. In the case where
light is periscoped downwardly, the bulk of the viewer's optics can be
placed above the head to provide to the binocular all the advantages of a
periscope. Provision is made to enclose each of the occular paths to the
eyepieces in light-tight tubes to prevent light scattering.
By the expedient of placing a zoom system within the periscoped downward
paths, the relay of the first image to the eyepiece occurs with variable
magnification. The gimbaled optical system is biased by a pulsed optical
circuit using notch filter optical centering with pulse width modulation.
Provision is made to adjustably compensate for displacement and resultant
angular velocity, acceleration, and jerk. Resonance is naturally avoided
as torquing forces are not applied where inertial centering of the
compensator is sufficient.
OTHER OBJECTS AND ADVANTAGES
An object of this invention is to disclose a new stabilizing element in
which side-by-side binocular paths can be stabilized. The element includes
at least five reflective surfaces--two dedicated to each light path and an
intermediate common surface to which both light paths are aligned. The two
mirrors dedicated to each light path are angulated so as to include
parallel lines on their surfaces. The mutual mirror is fixed in a plane,
so that lines parallel to lines in both mirror sets can be described on
its surface. The three mirror surfaces requiring stabilization for each
separate optic train are aligned, so that light is reflected and displaced
by the mirror system to result in stabilization as described in Humphrey
U.S. Pat. No. 3,475,073, issued Oct. 28, 1969. Stabilization effected by
each optical path is in convergent light to a stabilized image plane
relative to the instrument case, as set forth in the Humphrey patent.
An advantage of this invention is that no double cardan joint is required;
one for each eye path. A single cardan joint system is required for each
eye path. A single cardan joint system independently corrects both paths
and eliminates the requirement for any interconnecting linkage between
paired cardan joint systems; one for each eye path. The use of a single
cardan joint with a large moment of inertia about the pivot center
precludes consideration of stiction that have affected prior art.
A further advantage of this invention is that the disclosed stabilizer is
naturally pivoted at its center of gravity. Optical and stabilizing parts
naturally provide to the stabilizing element is own balanced counterweight
system about a center of gravity at the pivot point.
Yet another advantage of the disclosed stabilizers is that the paired
optical paths intersect at a common mirror without interference from one
another. Since mirror optics are used, the disadvantage of producing
optical aberrations with off-axes movements--that is encountered with
stabilizing prisms in converging light--can be avoided.
A further advantage of the gimbal stabilizer is that true stabilization can
occur without precession mechanics and "swimming" of the image. Another
advantage of the stabilizer is that it has a relatively low mass compared
with the prior art. Not only may the stabilizer be manipulated with
relative ease for correction, but the overall mass of the resultant
instrument is greatly reduced.
A further advantage is that the optical path conveniently detours around
the cardan joint. Thus, pivot of the stabilizer at the center of gravity
can occur with no interference to the optical paths.
Another object is to disclose a preferred optical path for the light
interior of the binocular after the image has been stabilized. According
to this aspect of the invention, light is reflected downwardly and across
the case by a second set of reflecting and displacing elements.
A further object of this invention is to disclose optical paths after
stabilization, which restore image parity and provide more convenient
processing of the stabilized signals. According to a preferred embodiment,
after the light has produced a stabilized image, it is passed through a
second displacing and reflecting assembly, which relays the light, so that
it ends up moving substantially parallel to a direction in which it was
initially received by the objective. The light is then relayed through a
vertically disposed zoom system and then periscoped to paired eyepieces.
An advantage of the preferred optical system is that the periscopes may be
rotated to provide variable interoccular spacing.
A further advantage of the periscoping to each ocular is that the bulk of
the stabilizer can be elevated to a position significantly higher than the
user's head. In this case, the binocular acts as a conventional periscope
with all the advantages thereof. For example, in military and police
viewing, observations either over or under obstacles can be made, so that
exposure of the viewer is either minimized or eliminated.
Another advantage is that the light paths are particularly suited for the
placement of zoom optics. Moreover, the zoom optics are in a position
relative to the viewer such that they can be manipulated to provide the
personal viewing advantages now only obtainable by rigidly held zoom optic
television cameras operated by skilled camerapersons.
A further advantage of the overall optical path is that it converts what
would be an undesirable "pseudoscopic" path into a path that restores true
stereoscopic viewing. Considerations of pseudoscopic paths will be
discussed below.
A further object of this invention is to encase a stabilized binocular in a
housing that conforms to the anatomy of the viewer, so that the horizontal
lineal distance between the objective and eyepiece is compressed. The
stabilizing element in cooperation with the optical paths extends
downwardly a substantial distance below eye level to a position
appreciably below the chin of the user. This path is surrounded by an
opaque housing, which may be conveniently grasped between the shoulders
and below the throat by a viewer having his elbows at his side. The hands
of the viewer, with the palms opposed, hold the instrument case. The
instrument, so held, is embraced to the upper torso of the viewer at the
chest, head, and neck.
One advantage is that such binocular casing can be held by a viewer of
virtually any age for a long period of time without fatigue. The user is
not required to brace at a distance in front of his eyes the mass of a
magnifying optical instrument.
A further advantage of this invention occurs when the binocular is panned.
Since the viewer in grasping the instrument in effect embraces the
instrument, both viewer and instrument in rapid panning can only turn
together about their common center of gravity. The result is that the
viewer, in embracing the instrument and turning the whole of his body,
rapidly learns how to aim the instrument with a high level of comfort.
Since ambient tremulations--including those of the body--are stabilized
out of the optical train, the instrument may be held securely in a relaxed
grip. The line of sight is then directed with precision by the mass of the
upper torso (including the head and neck) to pick out distant objects for
relatively high magnification with viewer comfort. In a normal binocular,
the viewer "sights" the instrument by looking "over" it. In this
binocular, he sights by looking, at the same height, to left or right of
the case.
Another advantage of the overall configuration of this binocular is that
the digits of the viewer are free for manipulating instrument controls,
such as caging, focus and power of zoom. For example, while the opposed
hands and fingers are grasping the binocular, the thumbs can be free for
manipulating respective controls of zoom and focus.
Another advantage of the overall configuration is that it permits such a
full view, and also provides a forehead rest so that user can keep his
eyes at the proper distance from the oculars, without contact between
ocular eye shields and spectacle surface.
A further object is to disclose an optical-magnetic system for biasing a
stabilizer element to a neutral position. According to this aspect of the
invention, a pulsed light source occulted by an aperture affixed to the
cardan joint stabilizer is utilized. This light source impinges upon a
multisegment light detector, which detects and amplifies from each segment
the count produced by pulsing the light sources. The amplified output from
the counter applies a magnetic bias to the stabilizer element dependent
upon stabilizing element displacement of the stabilizer with respect to a
neutral position relative to the housing. Centering of the stabilizer
element occurs while accidental angular vibration--of relatively high
frequency--is avoided.
A surprising advantage of the optical-magnetic system herein disclosed over
that of the prior art is the absence of bias (preferably torquing), where
simple inertial stabilization is sufficient. In many prior art systems,
constant spring force restoring torques are utilized. Even when such
systems undergo small displacements, the spring force exerts some
restoring force that changes the true response of the compensator to
something other than the desired inertial compensation. A swimming motion
with resonance can result. In the present invention, since the pulsed
optical circuit has pulse width modulation, no bias is effectively applied
where inertial stabilization provides adequate centering of the
compensating element relative to the case.
An advantage of this aspect is that gyroscopes and their requirement for
precession corrections are avoided. Moreover, gyroscopes require
considerable time in coming up to speed. The complete avoidance in the
present system of gyroscopes eliminates precession considerations and
startup delays.
A further advantage of the optical centering device is that fluid
stabilizers with their generated optical wedges, change of viscosity, and
index of refraction are eliminated. Yet another advantage of the
optical-magnetic centering is that it naturally avoids resonance or
enhanced vibration at resonant ambient vibration inputs.
An additional advantage of the electromechanical centering herein disclosed
is that separate inputs for separate components of displacement to the
gimbaled system can be differentiated out and separately compensated. For
example, separate adjustments to restoring force can be made for angular
displacement, velocity, acceleration, and jerk.
A further advantage of the pulsed optical circuit disclosed is that damping
characteristics of the circuit are easily modified. For example, nonlinear
production tolerances of given instruments can be compensated for in the
disclosed manufacture.
An object of this invention is to disclose an improved monobinocular light
path utilizing a beam splitter wherein the beam splitter is provided with
different light inputs from two directions. In a first input direction the
beam splitter receives stabilized light from the objective and transmits
the light to paired occular paths. In the second input direction the beam
splitter receives unstabilized light from a finder and transmits the light
from the finder to the paired occular paths. By the expedient of
addressing the beam splitter along orthogonal paths and shifting a
mechanical shutter to obscure one or the other of the occular paths,
improved finding results.
An advantage of this aspect of the invention is that there is no shifting
of the eye between the objective and the finder. Consequently, a person
utilizing the instrument may shift indiscriminately between the
unstabilized finder and the zoom stabilized optics.
A further advantage of the disclosed finder and beam splitter combination
is that rotation of the finder path can occur in a periscope arrangement
to virtually any convenient position within the case. There results finder
optics having extreme flexibility.
Yet another advantage of this invention is that both the finder and the
main optics are adaptable to alternation into and out of the viewing path
by means of a simple mechanical shutter. The viewer can readily shift
between optic paths.
A further object of this invention is to disclose the use of an inverse
telephoto lens in combination with the beam splitter. According to this
aspect of the invention, the periscoped optic path into the finder is
provided with an inverse telephoto optics. These optics effectively throw
a wide angle beam path into the beam splitter. There results a three power
wide angle field utilized with the finder.
An advantage of this aspect of the invention is that the finder optics
provide to the viewer along the same eye path as the main objective optics
a viewing path. Objects of interest in the finder path may be readily
identified and thereafter viewed at high optic power for close examination
without movement of the viewer'eye.
Other objects, features, and advantages of this invention will become more
apparent after reference to the following drawings and specifications, in
which:
FIG. 1 is a perspective view of the overall optical train and stabilizing
element of this invention, the configuration of the enclosing optical
housing being shown in broken lines and the zoom optical system only being
schematically shown;
FIG. 2 is a perspective view of the stabilizing element illustrating the
five mirrors for stabilization and a protruding system for a pulsed
optical circuit actuating four magnets to effect centering of the
invention;
FIGS. 3a-3e are circuit diagrams of the pulsed optical circuits utilized
with this invention;
FIG. 4 illustrates a viewer utilizing the preferred embodiment of the
instrument;
FIG. 5 is a perspective of the preferred embodiment of the instrument from
the eyepiece side illustrating the position of instrument controls for
manipulation by the thumbs of the viewer;
FIGS. 6a, 6b and 6c are computer generated schematics of the preferred zoom
optic system utilized with the binocular of FIG. 1;
FIGS. 7A and 7B are respective front elevation perspectives and rear
elevation perspectives of the preferred embodiment of a monobinocular
according to this invention; and
FIG. 8 is a perspective view of this invention in the vicinity of the beam
splitter illustrating the duplicate paths of incidence on the beam
splitter from the objective optics and finder optics.
Referring to FIG. 1, stabilized binocular B of this invention is
illustrated. The shape of the case as illustrated in perspective is drawn
in broken lines with only the right objective O.sub.r and left eyepiece
E.sub.P being shown. A viewer is schematically illustrated by a left eye
V.sub.l addressed to the left eyepiece E.sub.l.
Outlining the disclosure hereafter, the mirrors for the left eye path will
first be traced and identified. Thereafter, mirrors for the right eye path
will be merely identified. Next, the construction of the stabilizer unit
will be set forth with respect to FIG. 2, so that the overall operational
mechanics of the invention can be understood.
A 60-millimeter objective having a focal length in the order of 1 foot is
placed and rigidly mounted with the case of the instrument. Light
convergent from the objective first impinges upon a first stabilized
mirror 31, a second stabilized mirror 22, and a third stabilized mirror
33, which together form part of the stabilizer S of this invention.
The functions of the movable and gimbaled mirrors 31, 22, and 33 of
stabilizer S will be described briefly. These respective surfaces are
arranged in a fixed angular relationship with respect to each other, so
that the light beam from the objective lens is reflected from surface 31
to surface 22 and then to surface 33. The light entering the first of the
three surfaces will thus exit from the third of the three surfaces at a
point transverse to the light entering. Exiting light leaves from surface
33. Thus, the array of mirrors 31, 22, and 33 in effect reflects and
displaces the light.
Another way to define the alignment of the mirrors 31, 22, and 33 is to
realize that each of them is capable of describing mutually parallel lines
on their surfaces, these lines being parallel to all other similarly
parallel lines on the remaining mirror surfaces. Mirror 31 can have line
44 described on its surface; mirror 22, line 45; and mirror 33, line 46.
These respective lines 44, 45, and 46 are all parallel to each other. This
reflection and displacing function is adequately described in Humphrey
U.S. Pat. No. 3,475,073 and will not be further set forth here.
Since mirrors 31, 22, and 33 are the stabilizing mirrors of the system for
the left occular path and are gimbaled about the case at a gimbal G (only
schematically shown in FIG. 1), the remainder of the mirrors and lenses
illustrated are all rigidly fixed to the case. Because of the limitations
of drawings, such rigid bracings are not shown but are to be understood as
present by the viewer. The remainder of the optical path of the binocular
will be described. Thereafter, the description will return in detail to
the disclosed stabilizer optics and mechanism.
It will be understood by those skilled in the art that the ocular paths
between separate oculars and objectives should not be interchanged. If
they are, this imparts to the viewer a most unnatural view. Specifically,
the viewing phenomenon has been described by calling it "pseudoscopic."
In pseudoscopic vision, unnatural results occur. For example concave
surfaces appear convex and vice versa. Additionally, a ball thrown so as
to pass behind a blocking frontal object appears unnatural in its flight.
At first, it appears to be headed in front of the object. Upon reaching
the object, it disappears from view. Upon passing on the other side of the
object, it suddenly reappears at what seems to be a spatial interval in
front of the object. Naturally, the elimination of this pseudoscopic
phenomenon requires that original right and left correspondence be
restored between the right objective and right eyepiece on one hand and
left objective and left eyepiece on the other.
Referring to FIGS. 6a-6c, an optically compensated zoom system is
illustrated. Its design may be arrived at by those skilled in the art from
Reymond U.S. Pat. No. 2,778,272, issued Jan. 22, 1957. Additional
reference may also be had to: U.S. Pat. No. 3,454,686, issued Nov. 23,
1948; Cuvillier U.S. Pat. No. 2,566,485, issued Sept. 4, 1951; Bergstein
et al. U.S. Pat. No. 2,906,171, issued Sept. 29, 1959; and Back U.S. Pat.
No. 2,913,957. FIGS. 6a-6c all show fixed lenses generally denominated 72
with movable lenses, generally denominated 71 moving therebetween. In a
possible design here presented, movable lenses 71 move up and down in
tandem parallel to the axis 52 of the lower vertical section of the case.
So moving, they effect the zoom of the image 70 for each of the respective
eyepieces E.sub.r and E.sub.l.
The system moves from 32 power in FIG. 6a to 16 power in FIG. 6b to 8 power
in FIG. 6c. Field lens 50, mirrors 142, 143 and 144 are all schematically
illustrated. It can thus be seen that the optically compensated zoom
system fits between the mirrors 141 and 143. The movable lenses fit into
the vertical space between mirrors 141 and 142. FIG. 1 is illustrated with
the lenses shown in the position of FIG. 6a.
Reymond in his U.S. Pat. No. 2,778,272 issued Jan. 22, 1957 has this system
disclosed. As can be seen from FIG. 6, the adapted Reymond system
incorporates a fixed position positive lens element between a pair of
overall negative elements that are coupled and moved together. Paired
fixed positive lens couplets are shown at each end of the system; the
couplet nearest the eyepiece being separated to permit mirror 142 to be
inserted.
In the preferred embodiment of FIGS. 6a-6b, four negative lenses move
together, two such negative lenses being assigned to each eye path. The
movement of the four negative lenses in the parallel relay systems
produces a simultaneous and identical zoom ratio of 4 power zooming from
32 power to 8 power for each eye path with no change in focus.
Referring to FIG. 2, the stabilized element S now will be described in
detail. Three discrete categories will be set forth. First, the
mirror-mounting gimbal system G and the support portion of stabilizer S
will be discussed. Second, the mirror surfaces will be briefly described.
Third, the active optical and mechanical components for centering the
invention will be set forth.
Stabilizer element S is mounted originally to a housing of binocular B by
an arm A. Arm A communicates to a conventional cardan joint G. Joint G is
fastened at its inner portion to arm A and at its outer portion to a
metallic support 81 for the stabilized mirrors system S.
The pivot of cardan joint G is conventional. Pivot is provided about a
first axis X shown schematically by arcuate line 82. Pivot likewise occurs
about an axis and shown schematically by arcuate line 83. It will be noted
that there is no pivot about the Z axis. Thus, when the instrument is
"rolled" from side to side, the stabilizer assembly S likewise rolls from
side to side and has no motion relative to the housing of binocular B.
Each of the mirrors 21, 23, 31, and 33 is supported upon respective mirror
supporting arms 91, 92, 93, and 94. These arms are all integral to plate
81 and rigidly fastened thereto, so that vibration does not produce flex
that would destroy alignment of the resultant image.
From the top and bottom portions of plate 81, there extends a U-shaped
member 85. At the upper ends of U-shaped member 85, fastening to plate 81
occurs. At the forward portion of U-shaped member 85, mirror 22 is rigidly
secured. The respective mirrors 21, 22, 23, 31, and 33 are fixed in angle
to include parallel straight lines 41, 42, 43, and parallel lines 44, 45,
and 46 previously described. Since mirror 22 includes lines 42 and 45, the
plane of mirror 22 is fixed with respect to both optical systems by the
orientation of the other mirrors 21, 23 and 31, 33.
In practice and for overall convenience of optical configuration, it has
been found that mirrors 23 and 33 can be mounted at a distance closer to
common mirror 22 than mirrors 21 and 31. Although this is not essential,
for overall configuration of the optical case, some mirror inward movement
may be desired.
So far, it will be understood by the reader that the system thus far
described will work to effect stabilization: when the instrument is
roughly centered on a distant object and manipulated so that the arm A is
free to pivot about stabilizing element S at cardan joint G, image
stabilization will occur. However, when the cardan joint reaches the end
of travel, abrupt motion of the stabilizer S will occur. To prevent this,
torquing system M is fixed to the lower bottom portion of U-shaped member
85.
Torquing system M applies magnetically a bias (here a torque) to the
stabilizer S. During high frequency angular vibration of the binocular B,
the inertial mass of the stabilizer S overcomes any torque, and the
stabilizer S remains at its gimbaled orientation in space. During lower
frequency vibrational movements, such as those encountered in panning of
the instrument, the torquing system M dominates the overall orientation of
the stabilizer S. A gradual and on-average panning of the image is seen.
To illustrate the function of the torquing system, its optical and magnetic
portions will first be described with reference to FIG. 2. Thereafter, the
circuitry for the torque system will be set forth with respect to FIG. 3.
U-shaped member 85 has a hollow tube 101 affixed to its back section. Tube
101 is about 3/4 inch in diameter and has affixed its outermost end an
iron dish 104, which is ferromagnetic with an inner radius of curvature
described about the axes of cardan joint G. Dish 104 should be formed with
an outer metallic ring thickening 105, so that it may be attracted by a
plurality of electromagnets.
It is preferable to use four electromagnets placed to attract dish 104 at
thickened ring 105 to pivot about the cardan joint G. Magnets 106 and 107
act along the Y axis and cause panning of the stabilizer S in azimuth.
Magnets 108 and 109 act along the X axis and cause panning of the
stabilizer element S in pitch. As has been previously set forth, the
stabilizer element is rigid in roll. Thus, a rocking side-to-side movement
of the entire binocular does not produce a corresponding rocking movement
of the stabilizer relative to the binocular B.
The invention illustrated utilizes an optical-sensed centering system.
Specifically, a light-emitting diode 110 is driven by a pulsed circuit to
the order of 20 pulses per second. Diode 110 emits light into tube 112
through an aperture 114. Tube 101 terminates in a mirror 115 along the
axis 80 of the stabilizer element S. Light is directed by mirror 115
centrally down a path of tubing 101 and out through an aperture 118 in
disc 104.
A four quadrant light-sensing element 120 receives light via the tube 112
from light-emitting diode 110. This light for varying excursions of the
stabilized element S is occulted by the borders of aperture 118 in
magnetic disc 104. As occultation occurs, one or more of the
photosensitive quadrants of detector 120 will be occulted. As these
quadrants are occulted, sensing circuitry described with more
particularity in FIG. 3 can apply magnetic bias to the selected magnets.
This results in torque being applied to the compensator. As the magnetic
bias is applied, a magnetic biasing force is applied to the stabilizer
element S, so that it gradually resumes over a prescribed period a
centered position relative to the case of the binocular B.
Referring to FIG. 3a, an electronic circuit is illustrated in block
schematic form for positioning the mirrors of a stabilized optical system.
The circuit includes a pulsed light position detector 110, the output of
which is fed into a simple analog computer 200 which creates an error
output voltage proportional to the velocity and positional off-center of
the mirror assembly. This error output voltage modulates a pulse width
driver 220 feeding current pulses into magnetic energizers 250 coupled to
the mirror assembly. The magnetic energizers act to gently recenter the
mirror assembly with an action not detectable by the operator as
distracting or unpleasant.
Referring to FIG. 3d, the system is pulsed by a timer 201 driving light
source 110 because only occasional feedback is required in such a "loose
loop" servo system. Considerable savings in power are gained, allowing use
of smaller batteries, components, lower power dissipation, and lower
weight. The timer 201 shown in FIG. 3d outputs three signals. The first is
a clock signal T.sub.1 which operates light source 110. Secondly, there
are two inverted signals T.sub.1 and T.sub.2, with signal T.sub.2 being
clipped. These signals are used for circuit gating.
The light from the pulsed infrared LED falls on differential photo cells in
varying amounts as the angle of a mirror in the stabilizing assembly
changes. See FIGS. 2, 3a. These proportional signals are fed into current
to voltage amplifiers 211, 212, 214 and 215 used for impedance matching
and gain, to drive a voltage difference amplifier 216, 217. The 0.001
.mu.fd capacitors 221, 222, 223, 224 in the feedback prevent parasitic
oscillations. There are one of these detectors per axis used to quantify
the position of the mirror assembly.
The proportional output signal from each channel (X and &) is then fed
through an electronic analog switch 226, 227. These switches are gated on
during the LED light pulse (T.sub.1) and capacitors 230, 231 are charged
to the voltage present at that time. The charge is held and switches 226,
227 open. This voltage is buffered by a high impedance voltage follower
amplifier 233, 234 so that it will not discharge or drift during the
cycle. The voltage as held and amplified is routed to another analog
switch 235, 236 operated by pulse T.sub.1. The output passes to voltage
difference amplifiers 240, 241.
In between LED light pulses the voltage stored in the capacitors 230, 231
is transferred into other capacitors 238, 239 where it will be compared
with the following pulse gated into 230, 231, at the voltage difference
amplifier 240, 241 during th | | |
