United States Patent [19]
`Palmer
`
`US005847868A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,847,868
`Dec. 8, 1998
`
`[54] NIGHT VISION BINOCULARS
`
`94581 11/1983 Germany ............................. .. 359/412
`
`[75] Inventor: Gary L. Palmer, Bellevue, Wash.
`
`[73] Assignee: ITT Corporation, New York, NY.
`
`[21] Appl. No.: 627,149
`[22]
`Filed:
`Apr. 3, 1996
`
`Related U.S. Application Data
`
`[62] Division of Ser. No. 430,194, Apr. 27, 1995, Pat. No.
`5,537,261, which is a division of Ser. No. 108,989, Aug. 18,
`1993, Pat. No. 5,495,364.
`
`[51] Int. Cl.6 ............................ .. G02B 23/00; G02B 7/02
`[52] U.S. Cl. ........................ .. 359/407; 359/409; 359/808;
`359/815
`[58] Field of Search ................................... .. 359/399—432,
`359/513, 503—506, 894—855, 480—482;
`250/214 VT; 396/25—29; 361/752—754,
`517, 519, 535—536
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`9/1970 Akin, Jr. ............................... .. 359/413
`3,531,177
`4,171,480 10/1979 Wulms
`. 250/214 VT
`4,205,894
`6/1980 Filipovich et al. ..
`..... .. 359/412
`4,568,155
`2/1986 Shimizu ............. ..
`359/414
`5,000,556
`3/1991 Katsuma ..
`359/421
`5,426,286
`6/1995 Nair et al. .
`361/752
`5,455,746 10/1995 Sato et al. .
`361/752
`5,495,364
`2/1996 Palmer .................................. .. 359/412
`
`FOREIGN PATENT DOCUMENTS
`
`Primary Examiner—Thong Nguyen
`Attorney, Agent, or Firm—Plevy & Associates
`
`[57]
`
`ABSTRACT
`
`A night vision binocular assembly (10) capable of convert
`ing low light and infrared energy into a visible image. The
`night vision binocular assembly (10) includes at least one
`objective lens assembly (62), image intensi?er tube (64),
`collimator lens assembly (66) and diopter cell assembly (68)
`encased in an easy to assembly waterproof housing (16). The
`objective lens assembly (62), image intensi?er tube (64),
`collimator lens assembly (66) and diopter cell assembly (68)
`are all supported by a common base structure (80) within the
`housing (16). As a result, variations caused by thermal
`expansions and contractions are evenly distributed among
`the various optical elements, thereby preserving a predeter
`mined optical relationship between those elements. Simple
`button controls (28, 30, 31) are used to operate and adjust the
`night vision binocular assembly (10). The button controls
`(28, 30, 31) are disposed on a common circuit board (38). An
`elastomeric structure (36) is disposed between the circuit
`board (38) and the interior of the binocular housing (16). The
`circuit board (38) is af?xed to the interior of the binocular
`housing (16) in a manner that compresses the elastomeric
`structure (36) against the binocular housing (16) to provide
`a water tight seal. The elastomeric structure (36) has switch
`membranes or domed portions which extend through aper
`tures (37) in the housing (16) creating both a ?uid imper
`meable seal with the housing (16) and a means for the tactile
`engagement of the switches on the below lying circuit board
`(38).
`
`540393 5/1993 European Pat. Off. ............. .. 359/630
`
`6 Claims, 8 Drawing Sheets
`
`1
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`FLIR-1007
`FLIR Systems, Inc. vs CANVS Corporation
`Page 1 of 17
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`U.S. Patent
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`Dec. s, 1998
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`Sheet 1 of8
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`5,847,868
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`FLIR-1007 / Page 2 of 17
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`U.S. Patent
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`Dec. s, 1998
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`Sheet 2 of8
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`5,847,868
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`FLIR-1007 / Page 3 of 17
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`U.S. Patent
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`Dec. s, 1998
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`Sheet 4 of8
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`5,847,868
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`FLIR-1007 / Page 5 of 17
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`U.S. Patent
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`Dec. 8, 1998
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`Sheet 5 of8
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`5,847,868
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`FIG. 5
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`U.S. Patent
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`Dec. 8, 1998
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`Sheet 6 of8
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`5,847,868
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`FLIR-1007 / Page 7 of 17
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`U.S. Patent
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`Dec. 8, 1998
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`Sheet 7 0f 8
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`5,847,868
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`F I G . 7
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`U.S. Patent
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`Dec. 8, 1998
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`Sheet 8 of8
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`5,847,868
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`FLIR-1007 / Page 9 of 17
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`1
`NIGHT VISION BINOCULARS
`
`5,847,868
`
`This is a Divisional, of application Ser. No. 08/430,194,
`?led Apr. 27, 1995, now US. Pat. No. 5,537,261, Which is
`a divisional of application Ser. No. 08/108,989, ?led Aug.
`18, 1993, now US. Pat. No. 5,495,364.
`
`FIELD OF THE INVENTION
`
`The present invention relates to optical devices that
`enable a vieWer to observe objects at night or during other
`loW-light conditions. More particularly, the present inven
`tion relates to a handheld binocular system that can be
`manufactured at loW cost for sale to the general public.
`
`BACKGROUND OF THE INVENTION
`
`Night vision devices are Widely used in the military to
`provide soldiers, aviators and sailors With the ability to vieW
`objects at night or during other loW light conditions. As a
`result, many night vision devices are currently being manu
`factured according to eXacting military speci?cations and
`designs. Similarly, many such night vision devices are being
`manufactured for speci?c military applications such as part
`of the sights of various Weapons or as part of goggle
`assemblies that attach to an aviator’s or soldier’s helmet. As
`a consequence, many of the night vision devices currently
`being manufactured are neither affordable nor easily adapted
`to non-military uses by the general public.
`Night vision devices typically include an image intensi?er
`tube that converts infrared energy into visible light. Such
`night vision devices typically require sophisticated poWer
`supplies and circuitry to control the operation of the image
`intensi?er tube and sophisticated optical arrangements that
`direct the infrared energy into the image intensi?er tube and
`visible light aWay from the image intensi?er tube. In military
`applications, the various military personnel are trained in
`hoW to use and adjust the night vision devices they are
`issued. HoWever, a night vision device designed for use by
`the general public Would have to provide simple adjustments
`that can be readily operated by a variety of different users in
`a dark environment. Furthermore, a night vision device
`designed for use by the general public Would also require
`various adjustable optical characteristics that Would be easy
`to operate and adjust. Such a consumer oriented night vision
`device Would have Wide ranging application in regard to
`nighttime marine piloting, nighttime security, surveillance,
`hunting, ?shing, backpacking, navigation, underWater
`vision, search and rescue and laW enforcement.
`ITT Corporation, the assignee herein, manufactures many
`night vision devices for various applications. Night vision
`devices for military applications are exempli?ed by US.
`Pat. No. 5,084,780 to Phillips entitled TELESCOPIC
`SIGHT FOR DAY/NIGHT VIEWING and US. Pat. No.
`5,029,963 to Naselli entitled REPLACEMENT DEVICE
`FOR A DRIVER’S VIEWER. ITT Corporation, also has
`designed handheld night vision binoculars devices. Such a
`binocular device is exempli?ed in US. Pat. No. 5,444,568
`Which is a continuation of US. patent application Ser. No.
`07/954,006, entitled CONSUMER NIGHT VISION VIEW
`ING APPARATUS and ?led on Sep. 30, 1992, abandoned.
`In this application, a night vision binocular device is dis
`closed having simpli?ed adjustment controls, interpupillary
`adjustments and diopter cell focus adjustments. Related
`optical components that can be utiliZed in the construction of
`night vision binocular devices are shoWn in US. patent
`application Ser. No. 08/039,755, now US. Pat. No. 5,347,
`397, entitled DIOPTER CELL ASSEMBLY FOR A BIN
`
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`OCULAR VIEWING SYSTEM, and US. Pat. No. 5,117,
`553, entitled COLLIMATOR FOR A BINOCULAR
`VIEWING SYSTEM, both of Which are assigned to the
`assignee herein. These references shoW a diopter cell design
`and a collimator lens assembly for night vision binoculars,
`respectively. The assignee holds many other patents and
`applications related to image intensi?er tubes and related
`devices Which are of interest in regard to the present subject
`matter.
`As has been previously mentioned, an important applica
`tion for publicly available night vision devices is used on
`recreational boats. Boats often run at night utiliZing only
`their running lights for illumination. The use of night vision
`devices by the pilots of boats Will greatly increase visibility,
`resulting in less nighttime collisions and similar accidents.
`The night vision binoculars Will enable boaters to identify
`objects detected on radar, see land marks, read channel
`markers, detect navigational haZards, identify approaching
`vessels and much more. The environment of a recreational
`boat is less than ideal for a sophisticated electro-optical
`device such as a handheld night vision instrument. To
`survive in such an environment, the night vision instrument
`must be capable of Withstanding large temperature changes,
`impacts, and must be hermetically sealed to Withstand the
`high humidity environment and the possibility of being
`dropped into the Water. Furthermore, since most recreational
`boats are small, inexpensive craft, the night vision device
`must provide the same performance as military speci?cation
`night vision devices but at a greatly reduced cost so as to be
`affordable to the average boater.
`It is therefore the object of the present invention to
`provide a night vision device that is easy to hold, easy to
`operate, Water proof and provides the same performance as
`military night vision devices at a greatly reduced cost.
`It is a further object of the present invention to provide
`component parts for the above-mentioned night vision
`device that are easy to manufacture and assemble, thereby
`further reducing the cost of manufacturing the night vision
`device.
`
`SUMMARY OF THE INVENTION
`
`The present invention is a night vision binocular assembly
`capable of converting loW intensity light and infrared energy
`into a visible image. The night vision binocular assembly
`includes at least one objective lens assembly, image inten
`si?er tube, collimator lens assembly and diopter cell assem
`bly encased in an easy to assemble Waterproof housing. The
`objective lens assembly, image intensi?er tube, collimator
`lens assembly and diopter cell assembly are all supported by
`a common optical base or bed structure Within the housing.
`As a result, variations caused by thermal expansions and
`contractions are evenly distributed among the various opti
`cal elements, thereby preserving a predetermined optical
`relationship betWeen those elements.
`Simple button controls are used to operate and adjust the
`night vision binocular assembly. The button controls include
`an on/off sWitch, a brightness sWitch and a focus sWitch, all
`of Which being surface mounting sWitching elements that are
`disposed on a common circuit board Within the binocular
`housing. An elastomeric planar sheet having domed sloped
`integral sWitching actuating projections is disposed betWeen
`the circuit board and the interior of the binocular housing.
`The circuit board is affixed to the interior of the binocular
`housing in a manner that engages the elastomeric structure.
`The elastomeric structure is glued by means of a Waterproof
`epoXy or adhesive to the internal surface of the housing and
`
`FLIR-1007 / Page 10 of 17
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`5,847,868
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`3
`is held and maintained in position by a plurality of locking
`extensions Which align the elastomeric sWitch sheet With the
`circuit board. The domed projections of elastomeric struc
`ture extend through apertures in the binocular housing
`creating both a ?uid impermeable seal With the housing and
`With the domed projections providing a means for the tactile
`engagement of the sWitching elements on the circuit board.
`The present invention night vision binocular assembly is
`manufactured in a manner that promotes both ease of use
`and ease of assembly. The primary optical elements of the
`night vision binoculars all interconnect onto the common
`optical base or bed structure With a minimal number of
`mechanical fasteners. The diopter cell assemblies require no
`mechanical fasteners in their assembly and the binocular
`housing can be assembled to be Water tight Without the use
`of a gasket. As a result, the present invention night vision
`binoculars can be manufactured and assembled in a highly
`reliable and cost ef?cient manner, thereby making the night
`vision binoculars affordable to the general consuming pub
`lic.
`
`BRIEF DESCRIPTION OF THE FIGURES
`
`For a better understanding of the present invention, ref
`erence may be had to the folloWing description of an
`exemplary embodiment thereof, considered in conjunction
`With the accompanying draWings in Which:
`FIG. 1 is a front perspective vieW of one preferred
`embodiment of the present invention night vision binocular
`assembly;
`FIG. 2 is an exploded vieW of the embodiment shoWn in
`FIG. 1 to facilitate consideration and discussion;
`FIG. 3a is a cross-sectional vieW of a section of the
`housing of the present invention binocular assembly, shoWn
`prior to assembly;
`FIG. 3b is a cross-sectional vieW of a section of the
`housing of the present invention binocular assembly, shoWn
`after assembly;
`FIG. 4 is an exploded vieW of the electro-optical subas
`sembly contained Within the present invention binocular
`assembly;
`FIG. 5 is an exploded vieW of a diopter cell subassembly
`contained Within the present invention binocular assembly;
`FIG. 6 is a cross-sectional vieW of the region of the
`present invention binocular assembly containing the diopter
`cell subassembly, vieWed along section line 6—6 as
`expressed in FIG. 1; and
`FIG. 7 is a cross-sectional vieW of the image intensi?er
`tube contained Within the present invention binocular
`assembly, vieWed along section line 7—7 as expressed in
`FIG. 4; and
`FIG. 8 is a block diagram illustrating the electrical opera
`tions of the present invention binocular assembly.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`Referring to FIG. 1, there is shoWn one preferred embodi
`ment of the present invention night vision binoculars 10. As
`Will be explained, the night vision binoculars 10 have a
`single objective lens for receiving infrared and loW intensity
`light and tWo eye piece assemblies 12, 14 for vieWing a
`visible image created from the received light. As Will be later
`explained, the objective lens and the tWo eyepiece or ocular
`assemblies 12, 14 are adjustable to the physical and optical
`needs of the vieWer that is utiliZing the night vision binocu
`lars 10.
`
`4
`The optics and electronics of the night vision binoculars
`10 are encased in a Waterproof housing 16. The housing 16
`itself includes a upper half or section 18 and a loWer half or
`section 20 that are joined together to create a ?uid imper
`meable seal along a common joint 21 de?ned by the periph
`eral edges of sections 18 and 20 When the sections are
`coupled together. The housing 16 is preferably made of a
`material that is highly impact resistant, corrosion resistant
`and is light Weight. In a preferred embodiment, the housing
`16 is made of a thermoplastic material such as XENOY®
`PC/PBT resin alloy. HoWever similar thermoplastic materi
`als such as the XENOY® 2000 & 5000 Series thermoplastic
`alloys can also be used. These generally are polyester bond
`urethanes. These thermoplastics are supplied by the General
`Electric Company via the GE Plastics Division. Such mate
`rials are light Weight and provide the needed corrosion
`resistance and impact resistance. Furthermore, such materi
`als can be manufactured in a variety of bright colors. It is
`desirable to produce the night vision binoculars 10 With a
`brightly colored housing to facilitate the location of the
`binoculars should they be misplaced or accidentally dropped
`into a body of Water such as a lake or the ocean. The Water
`tight housing 16 of the night vision binoculars 10 is siZed to
`make the night vision binoculars 10 buoyant. Furthermore,
`the components of the night vision binoculars 10 are so
`distributed Within the housing 16 so that the night vision
`binoculars 10 Will ?oat in the upright position shoWn in FIG.
`1 or in the upside doWn position. This exposes the maximum
`surface area of housing 16 Which ?oats above the Water and
`thereby making the binoculars 10 more easy to spot in the
`Water.
`Since the Water tight housing 16 is preferably a thermo
`plastic material, the housing 16 is relatively rigid. To
`enhance the impact resistance of the night vision binoculars
`10, elastomeric material in the form of eyeshades 22, 24 are
`placed around each of the eyepiece assemblies 12, 14.
`Similarly, a elastomeric bumper 26 is disposed around the
`objective lens of the night vision binoculars 10. The elas
`tomeric material at these positions helps absorb the energy
`of an impact should the binoculars 10 be dropped. By
`placing the elastomeric material around the region of the
`eyepiece assemblies 12, 14 and the objective lens, it is less
`likely that the force of impact Will be transferred to these
`optical elements With enough energy to damage these ele
`ments. Furthermore, the elastomeric eyeshades 22,24 sur
`rounding each of the eyepiece assemblies 12, 14 shade a
`persons eyes from secondary light and provide comfort
`When vieWing through the night vision binoculars 10.
`Some of the electronic components contained Within the
`night vision binoculars 10 are controlled by actuatible
`elastomeric sWitch projections employed as actual buttons
`that extend through associated apertures in the upper half 18
`of the housing 16. The control buttons include an on/off
`button 28 for controlling the activation and deactivation of
`the binoculars 10, a focus button 30 for controlling the focus
`conjugate of the objective lens and a set of tWo brightness
`buttons 31 for controlling the brightness of the vieWed
`image.
`As Will be later explained, the night vision binoculars 10
`are manufactured With one set poWer of magni?cation. The
`night vision binoculars 10 may also be joined With a
`supplemental magni?cation lens 32 to increase the poWer of
`magni?cation. For instance, the night vision binoculars 10
`may come With an initial poWer of magni?cation of 3x,
`hoWever When the supplemental magni?cation lens 32 is
`added, the poWer of magni?cation may be increased to 8x.
`The supplemental magni?cation lens 32 shoWn has a
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`threaded end 34 that engages the night vision binoculars 10.
`Such interconnections systems are Well knoWn for joining
`telephoto lenses to cameras and any such knoWn intercon
`nection system may be employed. Similarly, interference ?t
`connections or other such mechanical interconnection sys
`tems may also be employed.
`Referring to FIG. 2, in conjunction With FIG. 1, it can be
`seen that domed projections creating the on/off sWitch 28,
`focus button 30 and brightness control buttons 31 are all
`unistructurally formed from a single molded piece of elas
`tomeric material. The elastomeric structure 36 is Water
`impermeable and the various domed projections are formed
`in the elastomeric structure 36 so that they pass through
`associated button apertures 37 in the upper half 18 of the
`housing 16. Some identifying indicia may be molded onto
`the buttons to help a person easily identify the function of
`the button. A circuit board 38 is disposed against the
`elastomeric structure 36 Within the housing 16. Membrane
`sWitches, such as keyboard type sWitches 40, or other
`pressure sensitive sWitches are disposed on the circuit board
`38 directly beloW the on/off button 28, focus button 30 and
`brightness control buttons 31. As a result, as the on/off
`button 28, focus button 30 or brightness control buttons 31
`are depressed, the membrane of the sWitch is actuated thus
`closing or opening the sWitch. These sWitches are bipolar as
`normally open or normally closed and When activated oper
`ate in the opposite state (ON or OFF) thus, a corresponding
`signal is generated Within the circuitry of the circuit board 38
`by the beloW lying pressure sWitch 40.
`Connecting apertures 41, 42 are disposed in the elasto
`meric structure 36 and the circuit board 38, respectively. In
`one embodiment, locking pegs or extensions 44 extend
`doWnWardly from the upper half 18 of the housing 16. The
`elastomeric sheet or structure 36 With the extending elasto
`meric domed buttons 28, 30 and 31 is placed over the
`plurality of pegs or locking extensions 44 via the apertures
`41 so that it is precisely located due to the plurality of spaced
`pegs and apertures. The elastomeric structure 36 is glued
`securely in place to the housing by means of a Waterproof
`adhesive such as methyl acrylate or a similar viscous Water
`proof epoxy. As a result, the elastomeric structure 36 is
`joined to the housing section 18 and provides a Water tight
`seal. The locking extensions 44 pass through the connecting
`apertures 41, 42 in the elastomeric structure 36 and the
`circuit board 38, Wherein the locking extensions 44 are heat
`sealed or otherWise formed to secure and locate the circuit
`board 38 in proper position With respect to the elastomeric
`structure. As a result, the elastomeric structure 36 is retained
`betWeen the circuit board 38 and the upper half 18 of the
`housing 10 assisting in the invention of a Water impermeable
`seal With the housing 16. The resultant compression of the
`elastomeric structure 36 helps the elastomeric structure 36 to
`further act as a gasket and create a seal around each of the
`button apertures 37. Consequently, should the night vision
`binoculars 10 be submerged in Water, the Water cannot enter
`the housing 16 through the button apertures 37 in the
`housing 16. It Will be understood that the use of a plurality
`of locking extensions 44 is merely exemplary and the circuit
`board 38 uses may be joined to the housing 16 using other
`schemes. In any event, the above techniques is extremely
`effective and inexpensive as the elastomeric structure When
`glued in position and located by the locking extensions
`automatically is aligned With the membrane sWitches 40 on
`the board 38 and forms a Waterproof cover and seal for both
`the board and the housing.
`As can be seen from FIG. 2, the upper half 18 and the
`loWer half 20 of the binocular housing 16 join together along
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`a complex peripheral path Which path is de?ned by the
`peripheral edge of the corresponding openings of the upper
`and loWer housing halves 18 and 20. HoWever, it is neces
`sary to join the upper half 18 and the loWer half 20 of the
`housing 16 together to create a ?uid impermeable seal along
`the common joint 21 (FIG. 1). Such a seal may be accom
`plished through the use of a suitably shaped gasket placed
`betWeen upper half 18 and the loWer half 20 of the housing
`16. HoWever, due to the complex shape of the peripheral
`edges, a gasket that Would operate to join and seal the edges
`Would be expensive to manufacture and highly labor inten
`sive to install. Thus, in order to avoid the use of a gasket the
`peripheral edge of the upper housing section 18 is formed
`With a depending peripheral projection (46 of FIG. 3A)
`While the corresponding edge of the loWer housing section
`20 is provided With a corresponding peripheral groove (50 of
`FIG. 3A). The projection and groove are specially shaped to
`enable an inner seal formation as Will be further explained
`When referring to FIGS. 3A and 3B. In this manner, When the
`top housing section 18 is placed in congruency With the
`bottom housing section 20 the projection engages the groove
`to enable insertion of the top half housing section 18 into the
`loWer half. As Will be explained, both the projection 46 and
`groove 50 are specially shaped to contain a suitable adhesive
`enabling an inner peripheral housing seal to be formed to
`thus provide a Waterproof seal for the housing 10 betWeen
`the upper and loWer halves Without the need for a gasket.
`Referring to FIG. 3a, there is shoWn a section of the upper
`half 18 of the housing 16 just prior to its being inserted into
`the corresponding groove of the bottom half 20 of the
`housing 16. The upper section 18 of the housing 16 has a
`projection 46 extending doWnWardly therefrom. The bottom
`surfaces 48, 49 on either side of the projection 46 lay in tWo
`different planes, With the bottom surface 48 proximate the
`exterior of the housing being higher than the bottom surface
`49 proximate the interior of the housing. The loWer section
`20 of the housing 16 has a shaped groove or receptacle 50
`formed along the edge that faces the upper section 18 of the
`housing 16. The top surfaces 51, 52 on either side of the
`receptacle 50 also lay in tWo different planes With the top
`surface 51 proximate the exterior of the housing being
`higher than the top surface 52 proximate the interior of the
`housing. For a purpose Which Will later be explained, the
`receptacle 50 on the loWer section 20 of the housing 16 is
`siZed to be signi?cantly larger than the projection 46 extend
`ing from the upper section 18 of the housing 16.
`Prior to the upper section 18 of the housing 16 being
`joined to the loWer section 20, an adhesive 54 is applied
`Within the groove 50 of the loWer section 20. The adhesive
`54 is material that bonds to the thermoplastic material of the
`housing 16 and cures to become Water impermeable. A
`suitable and preferable adhesive contains methyl acrylate as
`a component Which can be applied and employed similar to
`an epoxy using an activator Which is mixed With the adhe
`sive material. Such materials are available from ITW adhe
`sive systems, of 30 Endicatt Street, Danvers, Mass. 01923.
`There are other adhesives Which Will operate as Well. The
`adhesive has to be relatively viscous and hence not pour but
`act as an epoxy as being thick so it can be extruded to form
`the seal. Referring to FIG. 3b, it can be seen that as the upper
`section 18 of the housing 16 is joined to the loWer section 20,
`a larger gap 55 is created proximate the interior of the
`housing than is created proximate the exterior of housing. As
`a result, the adhesive 54 present betWeen the upper section
`18 and the loWer section 20 is directed toWard the inside of
`the housing structure. Excess adhesive that is extruded from
`the joint creates a bead 56 on the inside of the housing. The
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`5,847,868
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`bead 56, created by the surface tension of the adhesive 54,
`covers the entire joint along the inside of the housing 16.
`Notches 57, 58 are disposed on the upper section 18 and the
`loWer section 20 of the housing 16 at points proximate the
`exterior of the housing 16. As the upper and loWer sections
`18, 20 are joined, a semi-rectangular relief 59 is formed on
`the exterior of the housing 16 that runs along the joint
`betWeen the upper and loWer sections 18, 20. Excess adhe
`sive 54 that is extruded from the joint ?lls the back of the
`semi-rectangular relief 59 thereby providing a clean assem
`bly Without a highly visible line of adhesive. The presence
`of the adhesive 54 betWeen the upper and loWer section 18,
`20, in the semi-rectangular relief 59 and along the bead 56
`inside the housing 16, creates a barrier that hermetically
`seals the interior of the housing 16. Once the adhesive 54
`cures, a ?uid impermeable seal is created betWeen the upper
`and loWer sections 18, 20 of the housing 16 Without the use
`of a gasket. As a result, the upper and loWer sections 18, 20
`of the housing 16 can be joined in a cost effective and labor
`ef?cient manner.
`Returning to FIG. 2, primary electro-optical subassembly
`60 is shoWn and to be positioned Within the internal holloW
`of the housing beloW the circuit board 38. The electro
`optical subassembly 60 includes an objective lens assembly
`62 for receiving and focusing infrared energy, an image
`intensi?er tube 64 for converting the infrared energy from
`the objective lens 62 into a visible image, a collimator lens
`assembly 66 for collimating the visible image, a beam
`splitter 67 for dividing the collimated image and tWo diopter
`or ocular cell assemblies 68, 70 through Which the divided
`image is vieWed With binocular vision. Each housing half
`section 18 and 20 have partial apertures Which form full
`WindoW apertures as 74 and 72 When the housings sections
`or halves are secured or joined together. Accordingly, Win
`doW apertures 72, 74 are formed in the housing 16. The
`aperture 72 aligns With the objective lens assembly 62
`alloWing infrared energy to pass into the housing 16 and
`impinge upon the objective lens assembly 62. A protective
`WindoW 75 is positioned Within the aperture 72 through
`Which the infrared energy passes. The WindoW 75 is secured
`to the housing 16 With a ?uid impermeable seal or adhesive
`thereby preventing the ?oW of Water into the housing 16
`through the aperture 72. In a similar arrangement, tWo
`vieWing apertures 74 align With the diopter cell assemblies
`68, 70 to provide the ocular vieWing paths. Protective
`WindoWs 76 are positioned Within the vieW apertures 74. The
`protective WindoWs 76 are joined to the housing 16 With a
`?uid impermeable seal, (using the above described
`adhesive), thereby isolating the environment contained
`Within the housing 16. A light sensor 65 is disposed Within
`the housing 16. The light sensor 65 senses light through an
`aperture 69 in the housing 16. The complete aperture 69 is
`formed When housing sections 18 and 20 are joined together.
`The aperture 69 is aligned along an axis parallel to the
`longitudinal axis or optical axis of the objective lens assem
`bly 62. As such, the light sensor 65 operates detect the
`intensity of radiant energy that is impinging upon the
`objective lens assembly 62. This enables one to operate
`circuitry to block or deactivate the image intensi?er tube 64
`for excessive light levels Which could damage the screen of
`the tube. See for example, US. Pat. No. 5,146,077 entitled
`“GATED VOLTAGE APPARATUS FOR HIGH LIGHT
`RESOLUTION AND BRIGHT SOURCE PROTECTION
`OF IMAGE INTENSIFIER TUBE by Casert et al., issued on
`Sep. 8, 1992 and assigned to the assignee herein. That patent
`describes protection circuits as Well as describing GEN II
`and GEN III image intensi?ers. A protective WindoW 63
`
`15
`
`25
`
`35
`
`45
`
`55
`
`65
`
`8
`covers the aperture 69 in a ?uid impermeable manner,
`thereby protecting the light sensor 65 and the interior of the
`housing 16 from moisture and other contaminants.
`Referring to FIG. 4 in conjunction With FIG. 2, it can be
`seen that the objective lens assembly 62, image intensi?er
`tube 64, collimator lens assembly 66 and diopter cell assem
`blies 68, 70 all are supported by a common optical base or
`support structure 80. The common optical base 80 is “T”
`shaped having the top arm of the “T” of a planar con?gu
`ration With a right and left slots 98 and 99 positioned on
`either side of the central arm of the “T”. The central arm is
`of a semi-cylindrical shape extending from the top arm and
`for accommodating the objective lens, the image intensi?er
`and so on. Because of the common base con?gurations
`thermal expansion or contraction caused by a change in
`temperature Will cause the objective lens assembly 62,
`image intensi?er tube 64, collimator lens assembly 66 and
`diopter cell assemblies 68, 70 to be integrally effected thus
`maintaining the exact alignment for all such changes. As a
`result, the distances betWeen the optical components
`remains generally constant, eliminating distortions that
`could be caused by uneven thermal expansions and contrac
`tions. In the preferred embodiment the casings surrounding
`the lenses in the objective lens assembly 62, collimator lens
`assembly 66 and diopter cell assemblies 68, 70 have the
`same general coef?cient of thermal expansion as does the
`base structure 80 so as to promote a uniform response to any
`change in temperature and maintain the preset relationships
`betWeen the various optical components. Asuitable material
`for the common optical bed or base 80 is a poly carbonate
`plastic.
`In the shoWn embodiment, the beam splitter 67 is coupled
`to the collimator lens assembly 66 and is attached to the
`optical bas