U.S. patent number 3,747,530 [Application Number 04/590,149] was granted by the patent office on 1973-07-24 for window protector.
Invention is credited to Charles W. Tepper.
United States Patent |
3,747,530 |
Tepper |
July 24, 1973 |
WINDOW PROTECTOR
Abstract
A protector for an optical fuze window formed of a thin
polyester film spatially displaced in front of the window and
having a thin film of meltable wax deposited thereon.
Inventors: |
Tepper; Charles W. (Rochester,
NY) |
Family
ID: |
24361076 |
Appl.
No.: |
04/590,149 |
Filed: |
October 26, 1966 |
Current U.S.
Class: |
102/200;
244/3.16; 343/872; 102/213; 250/239; 359/894 |
Current CPC
Class: |
F42C
19/04 (20130101) |
Current International
Class: |
F42C
19/00 (20060101); F42C 19/04 (20060101); F42c
013/02 (); F42c 019/00 (); F42c 019/04 () |
Field of
Search: |
;102/70.2,92.5 ;244/3.16
;250/238,239 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Borchelt; Benjamin A.
Assistant Examiner: Webb; Thomas H.
Claims
What is claimed is:
1. In combination with the window of an optical fuze, a protector
for said window comprising,
a film of thermal insulating material disposed in the optical path
of said window and
a meltable coating applied to completely cover said film of thermal
insulating material.
2. The protector of claim 1 wherein said film of thermal material
is spaced from said window so as to form a pocket of air
therebetween.
3. The protector of claim 2 in which said film of thermal
insulating material is a formed from a polyester.
4. The protector of claim 3 wherein said coating is a thin film of
wax.
5. The protector of claim 1 in which said film of thermal
insulating material is convex in shape.
Description
The present invention relates generally to ordnance fuzes and more
particularly to an apparatus for protecting the lens of an optical
fuze.
In a rocket or projectile using an optical fuze, such as an
infra-red fuze, it is important to keep the lens, or window, of the
fuze clean to assure proper operation of the fuze in response to
impinging rays of infra-red energy.
Many problems have been encountered in the handling of infra-red
fuzes and in their operation while in a projectile or rocket in
flight. It has been found desirable to place a protective wax
covering over the window of the fuze but great difficulty was had
in placing the protector directly on the fuze lens without getting
fingerpints on the window. These fingerprints adversely affected
the operation of the infra-red fuze. Another reason for placing wax
or some type of window protector on the fuze lens is to prevent the
deposition of gun blow-by products on the outside of the window
when a projectile incorporating an infra-red fuze is fired from a
gun.
When a window protector has been placed over the fuze lens it is
desirable to remove this window protector while the projectile is
in flight in order that the infra-red fuze will operate when in
proximity to the target. Removal of window protectors has been
realized by the combination of the effects of stagnation
temperature and projectile spin. Under certain cold environmental
conditions the removal of the window protector was found to be
incomplete, thus adversely affecting the fuze sensitivity. Under
these cold conditions the heat applied to the window protector
would be dissipated by the fuze window, thereby not fully melting
the wax window protector. Furthermore, the presently employed
sapphire infra-red windows when directly covered with a wax coating
act as heat sinks and delay the melting of the coating by drawing
the heat therefrom. Resort to thin coatings of wax also proved
unsatisfactory since the coating did not dissipate the heat with
sufficient rapidity to entirely melt the wax before target
approach.
An object of the present invention resides in the provision of a
new and improved window protector for a fuze.
Still another object of this invention resides in the provision of
a thermally insulated window protector for an optical fuze.
According to the present invention, the foregoing and other objects
are attained by providing a window protector for an optical fuze
formed of a thin polyester film such as MYLAR, having good thermal
insulation qualities, spaced a small distance from the fuze window.
A thin film of wax is placed on the polyester film which is
completely removed by the heat generated when the fuze is in
flight. The polyester film and the spacing between the window and
the film act as good thermal insulators so that the window of the
fuze will not dissipate the heat generated when the fuze is in
flight.
Other objects and features of the invention will become apparent to
those skilled in the art as the disclosure is made in the following
description of a preferred embodiment of the invention as
illustrated on the accompanying drawing in which the sole FIGURE
schematically shows a preferred embodiment of the window protector
of this invention.
The sole figure shows an infra-red fuze assembly 1 capable of being
mounted in the nose of an ordnance vehicle, such as a projectile. A
sapphire window, or lens, 2 is held against a washer 3 which rests
in a counter-sunk opening 4 located in the nose portion or front
end of the fuze assembly 1. The window 2 is securely held in
opening 4 by a rubber seal, or washer, 5 forced into contact with
the window by a crimp ring 6 acted upon by a lip 7. The lip 7 is
formed by crimping or spinning an extension of the fuze casing over
the crimp ring 6 with sufficient pressure to force the crimp ring
into contact with the rubber seal 5 and in turn force the rubber
seal against the window 2.
A plastic film 8, preferably formed of Mylar, is inserted between
the crimp ring 6 and the rubber seal 5 to form a continuous surface
covering the window opening. The film is formed so as to protrude
between the surfaces of the crimp ring and the inside of the crimp
lip on the front of the casing, but not to extend above the crimp
ring 6. After crimping, air trapped between the window and the
thermal insulating film forms the film into a convex surface, i.e.,
the film bulges outwardly from the window, to enhance the thermal
insulation properties thereof. Melted wax 9 is then poured over the
film surface so as to completely cover the surface thereof. The wax
coating must solidify in contact with the crimp ring so as to be
held thereby and not be capable of working loose. The wax to be
used should be of a homogeneous mixture so as to form a consistent
coating throughout the film surface to assure the proper melting of
the coating during flight.
Obviously many modifications and variation of the present invention
are possible in the 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.
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