Encapsulated television camera and method and apparatus for fabricating same

A television camera is encapsulated in plastic material providing protection from environmental hazards. The camera, including a camera body, lens and lens cover glued to the lens, is embedded in and chemically bonded to the encapsulate material. A lens opening in the forward end of the encapsulate housing exposes the lens cover. A camera cable and pushrod extend from the rearward end of the housing and are chemically bonded to the encapsulate material. Individual light sources, partially embedded in the encapsulate material, are disposed in respective recesses oriented in an annular pattern about the lens opening. The encapsulation process employs a mold assembly having a base with a raised pedestal on which the lens cover is placed to support the camera. Multiple lamp receivers are disposed in the base in an annular pattern about the pedestal to sealingly receive the forward portions of respective lamps while leaving the remaining rearward portions exposed. At least one additional mold section mates with the base to provide an enclosure having a single opening at its top through which flowable encapsulate material may be poured.

BACKGROUND OF THE INVENTION 
1. Technical Field 
The present invention relates generally to television camera housings. More 
particularly, the present invention relates to television cameras embedded 
or encapsulated in plastic housings, and to methods and apparatus for 
encapsulating a television camera. The invention has particular utility 
for television cameras employed for pipeline inspection, and the preferred 
embodiment described herein is intended for that purpose. However, it is 
to be understood that the present invention has far broader utility, 
namely television cameras employed in security systems, nuclear systems, 
explosive environments, underwater environments and other hostile 
environments wherein the camera is typically subjected to shock, pressure, 
chemical and other environmental hazards. 
2. Discussion of the Prior Art 
Conventional television cameras designed for use in hostile environments 
are typically housed in sealed metal or plastic containers that are 
expensive in both material cost and assembly time. Moreover, although the 
housings for such prior art cameras may be adequate to serve as waterproof 
containers, the housed camera is generally not protected adequately 
against shock, certain chemical environments, etc. In addition, pressure 
sealed television camera housings tend to be too bulky and heavy to permit 
efficient use of the camera for security applications and the like. 
OBJECTS AND SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a television 
camera housing that protects the television camera against damage in 
substantially any hostile environment. 
A further object of the present invention is to provide a television camera 
embedded or encapsulated in a plastic housing that chemically bonds to the 
camera components to protect them against damage from liquids, pressure, 
shock, chemicals and other hazards and yet is sufficiently small to permit 
use of the camera in minimum space environments. 
Another object of the present invention is to provide an inexpensive method 
and apparatus for encapsulating a television camera in a plastic material. 
In accordance with the present invention, a small television camera, 
preferably of the charge-coupled device (CCD) type, is embedded or 
encapsulated in a plastic housing material. The housing has a lens opening 
exposing a transparent protective lens cover secured to the front surface 
of the camera lens by means of adhesive material that prevents water and 
other environmental fluids, as well as flowable encapsulate material 
during molding, from reaching the lens. The electrical cable for the 
camera, and possibly a pushrod for moving the camera and housing, project 
rearwardly from the encapsulate material housing. In a preferred 
embodiment, a plurality of auxiliary recesses are disposed in the housing 
in an annular pattern about the lens opening to receive respective light 
sources for illuminating the camera field of view. Portions of the light 
sources are embedded in and chemically bonded to the encapsulate material 
along with the wiring for the light sources, the wiring extending out from 
the housing via the camera cable. 
In fabricating the housing, a mold base is placed in a fixture. If the 
camera is to have self-contained illumination sources, individual lamps 
are placed in respective female recesses in the mold base and wired as 
required. The camera, with the lens cover glued in place, is pre-focused 
and placed in the mold base with the lens cover facing downward and 
resting on a raised pedestal that ultimately defines the lens opening in 
the housing. The rearward end of the camera is supported in the fixture by 
a hollow cylindrical support rod about which intermediate and top annular 
mold parts are disposed for subsequent deployment. Wires from the light 
sources and camera are appropriately connected and grouped to extend as a 
cable from the rearward end of the camera and then through a central 
aperture in the closed end of the top mold part. The internal and top mold 
parts are then lowered about the camera, and the support rod is forced 
downwardly to the extent necessary to urge the camera lens against the 
pedestal in the mold base in sealing abutment. The plastic encapsulate 
material is prepared and then poured through the annular passage defined 
between the aperture in the top mold part and the cylindrical support rod 
of the fixture. The poured encapsulate material is permitted to cool in 
place before the mold is removed from the fixture for curing, after which 
the molded assembly is removed. 
A unique feature of the described molding apparatus and method is that the 
mold itself supports all of the encapsulated components in proper mutual 
orientation without requiring separate support members. Accordingly, the 
hardened encapsulate material holds all the components in place in the 
final product. 
In addition, the encapsulate material chemically bonds to the periphery of 
the lens cover, the cable, and the pushrod in order to assure a complete 
seal for the internally housed components of the camera.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring specifically to FIG. 1 of the accompanying drawings, a television 
camera assembly 10 includes a solid, generally cylindrical housing 12 of 
encapsulate material filling all of the interior space surrounding the 
camera components. The encapsulate material is any plastic material 
suitable for the purpose, such as urethane, silicone, polystyrene, etc., 
and in the preferred embodiment is Andure 9000 urethane manufactured by 
the Anderson Development Company of Adrin, Michigan. Embedded within the 
encapsulate material 12 is a CCD television camera having a body portion 
11 with a lens 13 secured at its forward end by means of an intermediately 
disposed lens-to-camera adapter 16. By way of example, the camera may be a 
model WAT-902 manufactured by the Watec Company of Kawasaki City, Japan; 
however, various other small television cameras may alternatively be 
employed in accordance with the present invention and as determined by the 
intended end use for the overall assembly. A transparent lens cover 15 is 
secured to the front face of lens 13 by means of glue or other adhesive 
material applied in an annular pattern on the interior surface of the lens 
cover adjacent its outer edge. The glue or adhesive material may, for 
example, be Super Bonder 495 manufactured by Loctite Corporation. Lens 
cover 15 is configured to cover the entire front surface of lens 13 and is 
typically made of transparent scratch-resistant glass or plastic having 
structural, thermal and chemical properties consistent with the 
environment in which the camera assembly is intended to function. The 
front surface of lens cover 15 is exposed to the ambient environment 
through a recessed lens opening 14 at the front end of housing 12. The 
encapsulate housing material 12 is chemically bonded to the peripheral 
edge of the lens cover to assure a proper fluid pressure seal at lens 
opening 14 for the interiorally encapsulated camera components. 
A pushrod 17 is fixedly secured to the rearward end of camera body 11 and 
serves to permit the camera assembly 10 to be pushed or pulled through a 
pipeline, or the like, by forces applied longitudinally of the pushrod. It 
will be appreciated that the pushrod may be eliminated for camera 
assemblies that do not require a means for translating the assembly 
longitudinally when the assembly is in use. An electric cable 19 carries 
electrical wires for the camera assembly to a remote location and extends 
from the rearward end of the camera body 11 alongside the pushrod. Both 
cable 19 and pushrod 17 project rearwardly out from the housing and are 
chemically bonded to the encapsulate material 12 to assure a proper seal 
at their egress locations. 
Multiple small frusto-conical auxiliary recesses 20 are defined in the 
forward end of housing 12 in an annular pattern surrounding and spaced 
from the recessed lens opening 14. Each auxiliary recess 20 tapers 
inwardly and contains a respective light source 21 embodied as a light 
emitting diode (LED), an incandescent lamp, or other suitable illumination 
source. Electrical terminals for the light sources are embedded in the 
encapsulate housing 12 as are the rearward portions of the light sources 
and the electrical wiring 23 between the light source terminals and the 
rearward end of camera body 11. In the preferred embodiment there are ten 
light sources 21 arranged in a ring about lens cover 15. It will be 
appreciated that, for many television camera applications, there may be no 
need for self-contained light sources; in such cases, the camera assembly 
is fabricated without recesses 20, light sources 21 and the associated 
wiring. 
The method and apparatus for fabricating an encapsulated camera according 
to the present invention is illustrated in FIGS. 2 through 5 to which 
specific reference is now made. A mold assembly includes a base 30, an 
intermediate section 31 and a top section 32. The mold assembly may 
alternatively utilize only two sections (or, for that matter, more than 
three sections) as required by the ultimate camera assembly configuration. 
The mold sections may be made of any suitable plastic or metal material 
consistent with the encapsulate material to be poured and hardened 
therein. Mold base 30 is generally cup-shaped and has a centrally disposed 
raised circular pedestal 40 defined in its interior bottom surface. The 
pedestal is configured to form the lens opening 14 of the camera housing 
12. Specifically, the diameter of pedestal 40 at its top is slightly 
smaller than the diameter of lens cover 15. The sidewall of the pedestal 
is tapered slightly to provide an overall solid frusto-conical 
configuration to facilitate removal of the molded camera assembly from 
mold base 30 after the encapsulate material has been cured. From the base 
of pedestal 40, the interior surface of the bottom wall of the base 
extends radially outward a short distance before becoming upwardly arcuate 
to merge with the upstanding peripheral wall 44 of the base. In this 
curved or arcuate region there is provided a plurality of upstanding lamp 
receivers 42 of hollow frusto-conical configuration, open at their upper 
ends. The interior of each lamp receiver 42 is configured to engage a 
respective lamp 21. In this regard, the sidewall of lamp receiver 42 is 
preferably thin and flexible enough, at least at its upper end, to 
resiliently engage each lamp 42 and thereby provide a sufficient seal to 
prevent flowable encapsulate material from entering the receiver. The 
thickness of this sidewall increases gradually toward the bottom of the 
receiver to provide the frustoconical configuration for recess 20 in the 
final camera assembly. Lamp receivers 42 are equally spaced from pedestal 
40 to define an annular pattern of receivers about the pedestal. Likewise, 
lamp receivers 42 are disposed at equal angular intervals, and ten 
receivers are provided in the disclosed embodiment. It will be appreciated 
that the number, orientation and shape of lamp receivers 42 depend on the 
requirements for the self-contained illumination source in any given 
camera assembly. 
The upraised interior wall 44 of mold base 30 flares slightly outward at an 
angle on the order of two degrees to facilitate removal of the final 
molded product from the mold base. The upward-facing annular edge 46 of 
mold base 30 is provided with a plurality of recesses 48 spaced and 
configured to receive corresponding protrusions 49 from the 
downward-facing annular edge 50 of intermediate mold section 31, thereby 
assuring proper registry between intermediate section 31 and base 30 when 
the mold is assembled. Intermediate mold section 31 is generally annular 
with an interior wall 52 contoured to provide a continuation of the flared 
interior wall 44 of mold base 30, thereby assuring easy removal of the 
final molded product from mold section 31. 
The upward-facing annular edge 54 of intermediate mold section 31 is 
provided with a plurality of spaced recesses 55 configured and positioned 
to receive corresponding projections 57 from downward-facing annular edge 
58 of the top mold section 32, thereby assuring that the mold sections 31 
and 32 are in proper registration when the mold is assembled. 
Top mold section 32 has an inverted cup-like configuration, open at its 
bottom, with a central aperture 60 defined through its top wall. The 
interior wall surface 62 of top mold section 32 has a diameter at its 
lower end substantially equal to the diameter of the interior wall 52 of 
intermediate mold section 31 at its upper end. However, the internal 
diameter of top section 32 tapers or reduces gradually, at an angle of 
approximately three degrees, to facilitate separation of top mold section 
32 from the final molded product. At the upper end of top mold section 32, 
the interior wall 62 becomes arcuate to provide a rounded end for the 
final molded product. Aperture 60 has a diameter somewhat larger than the 
diameter of pushrod 17 so as to accommodate cable 19 passing therethrough 
and to provide an annular opening about the pushrod through which flowable 
encapsulate material can be poured into the assembled mold. 
The mold assembly is employed in conjunction with a fixture 70 having a 
bottom or platform 71, an upstanding rear wall 72 and a top wall 73 
extending parallel to the platform 71 and spaced therefrom by a distance 
corresponding to the height of the rear wall 72. That height exceeds the 
height of the assembled mold section 30, 31 and 32 by an amount sufficient 
to permit the steps described below to be performed. Top wall 73 has an 
aperture defined therethrough in alignment with the substantial center of 
platform 71. A hollow fixture rod 74 retained in the top wall aperture and 
is engaged by a tensioning nut 75 to permit selective longitudinal 
displacement of the rod. The fixture of is configured at its lower end to 
frictionally (or otherwise) engage the pushrod 17 or other suitable 
projection from the camera body to thereby hold the camera in place in the 
mold assembly. Annularly abutting shoulders of the pushrod and fixture rod 
(see FIG. 5) permit the fixture rod to apply downwardly directed forces to 
the camera unit, as necessary. 
The procedure for fabricating the encapsulated camera assembly begins with 
placement of mold base 30 on platform 71 of fixture 70. If the camera is 
to be provided with self-contained illumination, lamps 21 are inserted in 
respective lamp recesses 42 as best illustrated in FIG. 3. Lamps 21 may be 
individually inserted into respective receivers 42 and then electrically 
interconnected by appropriate wiring, as shown. Alternatively, the lamps 
may be pre-mounted and pre-wired on an annular circuit board and then 
inserted into the receivers 42 as a unit. The central opening in such a 
circuit board would necessarily be large enough to accommodate the camera 
body 11 therein. In either case, once the lamps are inserted and wired, 
the camera assembly may be positioned in mold base 30. Prior to this, the 
camera is tested and pre-focused as desired. In addition, lens cover 15 is 
secured over lens 13 in the manner described above and, if necessary, tape 
may be placed over the exposed lens cover surface to prevent encapsulate 
material from adhering thereto should any such material migrate between 
the lens cover and pedestal 40 during the molding process. The camera, 
including camera body 11, adapter 16, lens 13 and lens cover 15, is then 
secured to fixture rod 74 at pushrod 17. This may be done with the 
intermediate mold section 31 and top mold section 32 already disposed 
about the camera body 11; alternatively, mold sections 31 and 32 may be 
supported on the fixture about rod 74 prior to insertion of the camera, 
body into the fixture. By lowering fixture rod 74, the camera can be 
positioned in mold base 30 with lens cover 15 positioned on pedestal 40. 
Wiring for lamps 21, if they are present, is threaded through the mold 
sections to the rearward end of the camera body 11. Electrical cable 19 is 
brought out through aperture 60 in the top mold section along- side 
pushrod 17. Once the camera is properly positioned, the mold sections 31 
and 32 can be lowered to enclose the camera unit. 
The urethane or other encapsulate material is then prepared for pouring. As 
illustrated in FIG. 6, the urethane is heated to render it flowable, 
typically to a temperature of approximately 220.degree. F. The flowable 
urethane is then placed in a vacuum chamber where it is outgassed to 
remove any air bubbles. An appropriate catalyst or curative is then heated 
to approximately 140.degree. F. and mixed with the flowable urethane. The 
mixture can then be poured through aperture 60 at the top of the mold 
assembly to fill the entire mold cavity surrounding the camera components. 
Once the poured encapsulate has cooled, the mold assembly is placed in an 
oven and cured at a temperature of approximately 220.degree. F. for 
approximately sixteen hours to increase the speed of polymer crosslinking. 
Thereafter, the mold parts may be removed from the final assembled camera 
unit. 
As an alternative to pouring the encapsulate mixture through aperture 60, 
the mixture may be injected under pressure with a syringe, or the like, 
through a suitably provided injection port communicating with the lower 
part of the mold interior through mold base 30. This injection technique 
is less likely to entrap air bubbles in the encapsulate material. In 
addition, pressure molding and injection molding techniques are possible 
alternatives to the method described. 
For some applications it may be possible to eliminate the lens cover, 
particularly where the camera assembly is not intended for use in an 
environment that will adversely affect the exposed lens 13. Under such 
circumstances, tape or the like, would be placed over the lens 13 which 
would be positioned directly on pedestal 40 during the molding process. 
Cable 19 carries supply voltages, ground lines and the video signal line to 
permit remote viewing of the image received by the television camera. 
Typically, the various connections for the cable are made at the rear of 
the camera body, although for some applications, depending upon the camera 
type, it is conceivable that cable 19 may extend from a different location 
of the housing. Under any circumstances, the encapsulate material 
chemically bonds to the cable exterior within the housing. 
The encapsulated camera as described herein provides a rugged assembly 
wherein the camera components are effectively sealed against hostile 
ambient conditions, whether those conditions be water, pressure, dust, 
shock or chemical in nature. The camera components are suspended in the 
encapsulate material, and the mold serves to support all elements in 
proper position relative to one another without requiring separate support 
members that must remain within the camera housing or be removed so that a 
hole remains in the housing that must be separately filled with a plug, or 
the like. The encapsulate material chemically bonds to the internal 
components and fills all voids within the housing, whereby the internal 
camera components are entirely surrounded by a solid mass of encapsulate 
material. 
The present invention is not limited by the size or shape of the final 
camera assembly, although the invention has particular utilization for a 
small camera, particularly a CCD-type camera. For the preferred embodiment 
described above, the following dimensions are presented by way of example 
only: length of assembly between front and rear of housing 12, 4 inches; 
diameter of housing 12 at its widest point (i.e., intermediate the tapered 
sections), 1.875 inches; radius of curvature of housing 12 at rearward 
end, 0.75 inches; diameter of lens opening 14 in housing, 0.68 inches; 
longitudinal distance between front end of housing and point of maximum 
housing diameter, 2.160 inches; taper angle for auxiliary recesses 42, 
30.degree.; tilt of major axis of frusto-conical auxiliary recesses 42 
relative to longitudinal axis of housing, 9.degree.; spacing between axes 
of diametrically opposed auxiliary recesses 20, 1.354 inches; depth of 
auxiliary recesses 20 (on axis), 0.27 inches; depth of lens opening 14 in 
housing 12, 0.062 inches. 
There are numerous advantages to the encapsulate housing of the present 
invention. Among these advantages is that the cost of the housing is 
relatively low since the inexpensive urethane or other encapsulate 
material replaces a number of machined stainless steel pieces 
conventionally employed for sealed camera housings. The urethane elastomer 
serves as a shock material to protect the interior components from damage. 
In addition, the urethane is highly resistive to abrasion and holds up to 
the rigors of most applications in hostile environments much better than 
metal enclosures. 
For cameras employed in security applications, the protection afforded by 
the encapsulate material renders the camera substantially vandal-proof. 
For such applications, the electrical cable may be encased in a stainless 
steel tube of the type employed for pay telephones to thereby render it 
virtually impossible for someone to sever the electrical connections to 
the camera. 
The present invention also permits fabrication of a buoyant camera capable 
of floating, if desired. This would render it possible to float the camera 
in a controlled water flow to a downstream location (e.g., in a pipeline), 
terminate the flow, and pull the camera back while performing inspection. 
A buoyant camera can be fabricated by using RIM, or resin injection 
molding, for the encapsulated housing. The RIM process provides a solid 
film on the outside surface and a foam material interior, thereby 
permitting an increase in the buoyancy of the final product so as to 
permit it to float. 
From the foregoing description it will be appreciated that the invention 
makes available a novel camera assembly, a method for fabricating that 
camera assembly and apparatus for performing that method, wherein a rugged 
camera is the resulting end product and is capable of withstanding 
substantially any hazard in a hostile environment. 
Having described preferred embodiments of a new encapsulated television 
camera and method and apparatus for fabricating the camera, it is believed 
that other modifications, variations and changes will be suggested to 
those skilled in the art in view of the teachings set forth herein. It is 
therefore to be understood that all such variations, modifications and 
changes likely fall within the scope of the present invention as defined 
by the appended claims.