U.S. patent number 3,891,328 [Application Number 05/403,132] was granted by the patent office on 1975-06-24 for electro-optical liquid artificial horizon.
Invention is credited to William P. Hall, George R. Maupin.
United States Patent |
3,891,328 |
Hall , et al. |
June 24, 1975 |
Electro-optical liquid artificial horizon
Abstract
An electro-optical liquid artificial horizon utilizing a vidicon
tube. An enclosed, leak-proof transparent, fluid container is
attached to the face of the vidicon tube. A fluid partially fills
the container. The surface of the fluid interferes with the optical
image being resolved thereby creating an artificial horizon.
Inventors: |
Hall; William P. (Ventura,
CA), Maupin; George R. (Norfolk, VA) |
Family
ID: |
23594586 |
Appl.
No.: |
05/403,132 |
Filed: |
October 3, 1973 |
Current U.S.
Class: |
356/249; 33/377;
33/365 |
Current CPC
Class: |
G01C
15/14 (20130101) |
Current International
Class: |
G01C
15/14 (20060101); G01c 009/18 () |
Field of
Search: |
;356/143,148,248,249
;33/365,366,377,384,389 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wibert; Ronald L.
Attorney, Agent or Firm: Sciascia; Richard S. St. Amand;
Joseph M. Hollis; Darrell E.
Claims
I claim:
1. An instrument for generating an artificial horizon line
comprising:
a vidicon tube having a face;
a volume of fluid; and
an enclosed, transparent, leak-proof fluid container positioned
adjacent to said face of said vidicon tube such that light rays,
incident upon said vidicon tube, pass first through said fluid
container, said fluid container being partially filled with said
fluid so that a horizontal fluid surface forms in said container at
a fluid-air interface, said fluid surface interfering with a
portion of an image being optically resolved by said vidicon tube
creating an artificial horizon line capable of being visually
observed on a television monitor.
2. The instrument of claim 1 wherein said fluid container
comprises:
a collar connected to said vidicon tube surrounding the perimeter
of said vidicon tube face, said collar projecting outward from said
vidicon tube face;
means between said collar and said vidicon tube face to provide a
leak-proof seal;
a transparent plate connected to said collar forming an enclosed
compartment between said plate and said vidicon tube face, said
compartment being partially filled with said fluid; and
means between said collar and said plate to provide a leak-proof
seal.
3. The instrument of claim 2 wherein said fluid is transparent.
4. The instrument of claim 2 wherein said fluid is translucent.
5. The instrument of claim 2 wherein said fluid is opaque.
6. The instrument of claim 1 wherein said fluid is transparent.
7. The instrument of claim 1 wherein said fluid is translucent.
8. The instrument of claim 1 wherein said fluid is opaque.
9. A method for generating an artificial horizon line
comprising:
partially filling an enclosed, transparent, leak-proof container
with a fluid thereby forming a horizontal fluid surface within said
container at a fluid-air interface; and
positioning said container in the path of light rays from an
optical image impinging upon a vidicon tube, said fluid surface
interfering with a portion of an image being optically resolved by
said transducer creating an artificial horizon line capable of
being visually observed on a television monitor.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, generally, to artificial horizons
and, more particularly, to electro-optical, liquid artificial
horizons.
2. Description of the Prior Art
Some prior art artificial horizon systems utilize gyros and/or
synchros to generate signals to a servomotor. The servomotor then
positions a movable reticle with respect to a fixed reticle. Light
passing through the reticles is reflected into the line of sight of
an observer through a complex mirror system. Such systems require
expensive mechanical components that must be custom manufactured to
close tolerances. Moreover, extreme care must be exercised when the
components are fitted together so that an accurate artificial
horizon line will result. In addition, the system is subject to
mechanical failure as well as mechanical wear creating an
inaccurate or even a complete loss of the artificial horizon
line.
Other prior art systems utilize a disc or sphere inside a
fluid-filled container. The container bottom forms an arc upon
which the disc or sphere rolls thereby indicating the true horizon.
The fluid serves to dampen the movement of the disc or sphere. Such
systems suffer from inaccuracies created by vibrations. Also, in
such devices there is considerable rolling friction inasmuch as not
only does the sphere or disc come into contact with the bottom of
the container but there is considerable contact between the sphere
or disc and the sides of the tube. Thus, intolerable inaccuracies
may result from such systems.
Still other prior art systems utilize the surface of a fluid to
form an artificial horizon. Such systems contemplate eye
observation. This results in the introduction of parallax error.
Also, mercury is utilized as the fluid. Mercury is a heavy,
expensive and easily contaminable fluid. In addition, it is opaque
which is undesirable in some environments.
SUMMARY OF THE INVENTION
The general purpose of this invention is to provide an artificial
horizon that is more accurate and more reliable than prior art
devices. To attain this, the present invention utilizes, according
to one embodiment, a vidicon tube. A collar surrounds the perimeter
of the vidicon tube face. A leak-proof seal is formed between the
collar and the vidicon tube face. The collar projects outward from
the vidicon tube face. A transparent plate is attached to the
collar and spaced from the vidicon tube face. A leak-proof seal is
formed between the plate and the collar. The resulting compartment
is partially filled with a fluid. The fluid surface interferes with
the optical image being resolved thereby creating an artificial
horizon.
Accordingly, one object of the present invention is to reduce
reliance on mechanical components.
Another object of the present invention is to reduce system
complexity.
A further object of the present invention is to provide an
inexpensive system.
Another object of the present invention is to eliminate reliance on
mechanical precision of components.
A further object of the present invention is to eliminate
vibrational induced inaccuracies.
Another object of the present invention is to eliminate parallax
error.
A further object of the present invention is to provide a system
with maximum reliability.
Another object of the present invention is to provide a system with
maximum accuracy.
A further object of the present invention is to provide remote
observation of the artificial horizon.
Other objects and a more complete appreciation of the present
invention and its many attendant advantages will develop as the
same becomes better understood by reference to the following
detailed description when considered in connection with the
accompanying drawings wherein like reference numerals indicate like
parts in the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of a specific embodiment of the present
invention.
FIG. 2 is a front elevation of the specific embodiment shown in
FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Turning to FIG. 1, the numeral 10 designates a vidicon tube having
a face 12. Vidicon tube 10 is utilized as an optical transducer
that transforms light energy into electrical energy.
A collar 14 surrounds and is attached to the perimeter of face 12.
A leak-proof seal 16 is formed between face 12 and collar 14.
A plate 18 shaped to fit the inside diameter 19 (FIG. 2) of collar
14 is placed inside collar 14 but spaced from face 12. A leak-proof
seal 22 is formed between plate 18 and collar 14. Plate 18 is
transparent to light rays.
The chamber 20 bounded by face 12, collar 14, and plate 18 is a
leak-proof fluid container.
Collar 14 contains a hole 24 communicating with chamber 20. Cover
26 provides a leak-proof cover over hole 24.
A fluid 28 partially fills chamber 20. The fluid 28 is poured into
chamber 20 through hole 24. Fluid 28 may be mercury, alcohol,
silicone oil or any other suitable fluid substance which will flow
freely in chamber 20. Fluid 28 has a fluid surface 30 (FIG. 2).
Fluid surface 30 (FIG. 2) interferes with a portion of image 32
(FIG. 2) being optically resolved on the vidicon target (not shown)
of vidicon tube 10. The result is a thin line that corresponds to
the real horizon and is contained in the signal being generated by
the vidicon tube 10.
Preferably, the fluid 28 level will be near the top of chamber 20
since the image 32 focused on the vidicon face 12 is optically
inverted. Thus, the artificial horizon line seen on a television
monitor (not shown) will appear on the bottom of the picture.
Another advantage of having the fluid 28 level near the top of
chamber 20 is that constant wetting of vidicon face 12 and plate
18, resulting in formation of droplets thereon, does not occur with
consequent degrading of image quality.
It is noted that when vidicon tube 10 is rotated about its
longitudinal axis the artificial horizon line observed on the
television monitor (not shown) will appear to rotate.
However, when vidicon tube 10 is rotated about an axis parallel to
fluid surface 30 and perpendicular to its longitudinal axis, the
artificial horizon line observed on the television monitor
(assuming a transparent or translucent fluid) will become thicker
and then split into two lines. One line will move upward on the
television monitor while the other will move downward on the
television monitor. For example, as vidicon tube 10 rotates
clockwise about the axis parallel to fluid surface 30 but
perpendicular to its longitudinal axis, the interface of fluid
surface 30 with respect to face 12 moves downward while the
interface of fluid surface 30 with respect to plate 18 moves
upward. Thus, as the interfaces of fluid surface 30 with respect to
plate 18 and face 12 move, the artificial horizon line on the
television monitor appears to widen. However, as vidicon 10
continues to rotate at some point (depending on the physical
parameters of the fluid), the interfaces of fluid surface 30 with
plate 18 and face 12 will cause two separate artificial horizon
lines to appear on the television monitor. Then, as vidicon tube 10
rotates still further, these two lines will move farther apart on
the television monitor. The direction of rotation cannot be
observed from the television monitor but it can be discerned by
rotating the vidicon tube about the axis and observing the movement
of the two artificial horizon lines on the television monitor.
Further, it is noted that when vidicon tube 10 rotates clockwise
about an axis perpendicular to both its longitudinal axis and fluid
surface 30, fluid surface 30 will rotate within chamber 20 such
that, as viewed from vidicon tube 10, the right side moves upward
while the left side moves downward. Of course, a counterclockwise
rotation about the above stated axis would result in fluid surface
30 moving upward on the left side of chamber 20 and downward on the
right side of chamber 20.
The viscosity of fluid 28 imparts two significant parameters to the
system. An increase in viscosity of fluid 28 will produce a change
in reaction time by increased damping, e.g., if the vidicon tube 10
were to change position, the higher the viscosity of fluid 28, the
slower fluid 28 would move to assume the new equilibrium position.
Of course, a lower viscosity would result in a faster fluid
movement. Also, as the viscosity of fluid 28 increases, so does the
artificial horizons line width, as seen on the television monitor
(not shown) and visa versa.
Other factors affecting the artificial horizon line width are the
surface tension of fluid 28 and the distance between fluid 28 and
the target (not shown) of vidicon tube 10.
It is envisioned that a transparent, fluid container physically
separated from vidicon tube 10 may be utilized to form a chamber
for fluid 28. The container must be placed adjacent to vidicon tube
10 so that the light from the image resolved by vidicon tube 10
passes through the container before impinging upon the vidicon
tube.
Fluid 28 may also be transparent, translucent, or opaque, depending
upon the environment and use contemplated.
Some uses of the present invention, among others, include
applications in the fields of surveying, optical tracking, and
in-flight-simulation trainers as well as remote drone flying, and
undersea devices.
In summary, fluid surface 30 (FIG. 2) in chamber 20 interferes with
the image being resolved by vidicon tube 10 thereby creating an
artificial horizon line corresponding to fluid surface 30 (FIG.
2).
Obviously numerous modifications and variations of the present
invention are possible in light of the above teachings. It is
therefore to be understood that within the scope of the appended
claims the invention may be practiced otherwise than as
specifically described herein.
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