Simulated multi-pane glass panel

Information

  • Patent Grant
  • 6240685
  • Patent Number
    6,240,685
  • Date Filed
    Monday, December 13, 1999
    24 years ago
  • Date Issued
    Tuesday, June 5, 2001
    23 years ago
Abstract
A decorative building unit simulating a multi-pane, window or door. The decorative building unit is comprised of a glass support frame and a single glass panel having an outer surface mounted on or in the glass support frame. The glass panel has at least one simulated joint comprising at least two shallow spaced apart parallel grooves formed in the outer surface of the glass panel and a platform formed between the two spaced grooves. The size and spacing of glass support frame simulated muntins and platforms is such that, when mounted together, the simulated muntins and platforms align with each other to simulate a multi-pane beveled glass window or door.
Description




FIELD OF THE INVENTION




The present invention is directed to a decorative building unit of the type used for architectural applications, and, more particularly, to a decorative building unit simulating a multi-pane beveled glass window or door.




BACKGROUND OF THE INVENTION




In recent years, the interior and exterior design of buildings and structures, as well as the furnishings therefor, have employed increasing quantities of decorative glass. For example, it is now commonplace for glass sheets to be used in various types of doors such as shower doors, storm doors, patio doors, entry doors, bi-fold doors, and in decorative windows, mirrors, and other furniture and architectural applications. As the scope of architectural and design tastes expands, the industry has become increasingly receptive to glass sheet products which have unique visual effects. Accordingly, cost effective methods for constructing glass sheet products are being sought.




Kessler (U.S. Pat. No. 3,411,258) discloses a plastic false muntin system for giving a large single glass panel the appearance of a window or door with smaller panels. Special caps attach to the window or door frame and plastic grill pieces snap into place about these caps. Cribben et al. (U.S. Pat. No. 4,437,284) discloses a false muntin assembly for converting a single window pane into one having multiple panels by using muntin bars which snap onto metal clips that are affixed to the window panel. Likewise, Ouellette et al. (U.S. Pat. No. 4,970,840) discloses a window and grill which uses hidden clips to fasten a grill assembly on top of a single large pane of glass. Dazo et al. (U.S. Pat. No. 5,487,245) discloses a window or door construction on which muntins are attached on either side of a unitary piece of glass by way of small, spaced apart holes cut through the glass.




One particularly popular glass sheet design, which does not use a false muntin system, simulates traditional brass camed doors and windows. Grooves are formed in the glass surface in a pattern corresponding to a desired caming pattern and simulated caming is laid into the grooves so that the caming is inset in the glass (see, for example, U.S. Pat. No. 4,488,919 to Butler).




There is also known a convenient and cost-effective means and method for effectively simulating beveled glass panes in a decorative glass sheet to give the appearance of a traditional camed glass window or door. See U.S. Pat. No. 5,840,391 to Eichhorn et al. Eichhorn discloses a method for forming a plurality of grooves in a glass panel, including forming a pair of opposed, parallel, spaced apart grooves, the pair of spaced apart grooves relatively positioned such that the respective peripheral walls are disposed adjacent one another and define a platform extending between the grooves. At least one caming strip is adhered to the platform adjacent, between and along the peripheral edges of the spaced apart grooves.




Eichhorn also discloses that the decorative, simulative effect is enhanced when certain parameters are observed. A first wall width is preferably no greater than 15percent of a second wall width. Preferably, each second wall forms an angle with the outer surface of the glass panel of at least 2 degrees. Each first wall should form an angle with the outer surface of the glass panel of at least 45 degrees. Preferably, each groove has an overall width of from about 5 to 30 millimeters, and more preferably of 10 to 20 millimeters. The depth of each groove should not exceed 30 percent of the thickness of the glass panel. The glass sheet thickness is preferably from about 3 to 6 millimeters.




The disclosure in Eichhorn, U.S. Pat. No. 5,840,391, is hereby incorporated by reference in its entirety. However, Eichhorn is directed to a technique in which caming strips are adhered to a platform formed by adjacent parallel grooves to simulate a camed door or window. The strips must be aligned and affixed by glue or tape. This operation can become tedious.




SUMMARY OF THE INVENTION




The present invention, on the other hand, utilizes a different type of frame which greatly facilitates the manufacture of a simulated beveled French door or window. In this approach, a support frame is provided with frame members (hereinafter referred to as “simulated muntins”) extending between opposed side members and between opposed end members to form a grid. A glass panel is provided with simulated beveled joints. Each simulated beveled joint includes parallel spaced apart shallow grooves formed in the outer surface of the glass panel and a platform formed between the two spaced grooves. The size and spacing of simulated muntins and simulated joints is such that the muntins and platforms align with each other when the glass panel is mounted on or in the glass support frame. When assembled, the assembly looks like a paned window or French door frame with separate beveled glass panes.




In a preferred embodiment, the support frame includes a rectangular support frame having a pair of opposed spaced apart side walls and a pair of opposed spaced apart end walls. Each side and end wall has an L-shaped cross section which forms a recessed region for receiving a single glass panel. A plurality of simulated muntins extend between and are attached to the pair of side walls and a plurality of simulated muntins are attached to the pair of end walls. The simulated muntins may be attached to the support frame by nailing, tacking, gluing, screwing, or any other suitable attachment means. Alternatively, the simulated muntins may be formed as an integral part of the support frame. The support frame, once assembled with the desired number of simulated muntins, is prepared for receiving the glass panel. The glass panel corresponds in size and shape to the recessed region of the glass support frame such that it can be mounted in the recessed region with ease. The glass panel thickness is preferably between about 3 and about 6 millimeters. Alternatively, the support frame may be flat on the rear (without an L-shaped cross-section). In such a case, the glass panel is merely attached to the rear surface of the frame by appropriate hardware.




Desirably, the glass panel will have beveled regions extending between the side edges of the glass panel, beveled regions extending between the end edges of the glass panel, and beveled regions adjacent to the side edges and end edges. These beveled regions simulate joints in a traditional beveled window or door construction. The number and arrangement of beveled regions corresponds directly to the number and arrangement of simulated muntins. Each beveled region, except the beveled regions adjacent to the side and end edges, includes at least two shallow spaced parallel grooves that are formed in the outer surface of the glass panel and a platform between the two spaced grooves. The platform may be either the original outer surface of the glass panel, or if less height is desired, a flat region between the two spaced grooves formed in the outer surface. The beveled regions adjacent to the side and end edges may comprise a single shallow groove. Desirably, the depth of each groove should not exceed 30 percent of the thickness of the glass panel. The total width of each groove is preferably about 10 to about 20 millimeters. Each groove will have two wall surfaces. A first wall extends from a first peripheral edge to a groove apex bottom and a second wall extends from the apex bottom to a second peripheral edge. The second wall has a width greater than the width of the first wall. Preferably, each second wall forms an angle with the outer surface of the glass panel of at least 2 degrees. Each first wall should form an angle with the outer surface of at least 45 degrees.




The size and spacing of the support frame simulated muntins and the platforms is such that the simulated muntins and the platforms align with each other when the glass panel is mounted in the recessed region of the support frame. Latches, clips, or other suitable fasteners or holders secure the glass panel in the recessed region. While it is not necessary that the support frame be in contact with the glass sheet, there is a need to limit the distance between the simulated muntins and the glass sheet as much as possible, so that a user will be unable to observe that the window or door is not a true multi-pane construction. In this manner, the assembled building unit simulates a multi-pane beveled glass window or door. Depending upon the specific application, it may be desirable to place a spacer material between the platforms and simulated muntins to prevent vibration and noise. Again, the spacer material should be invisible to the user such that the appearance of a true beveled multi-pane window or door is maintained.




Another aspect of the present invention includes a support frame provided with simulated muntins extending between opposed side members and between opposed end members, a first glass panel provided with simulated joints having an outer surface mounted in the support frame, a second glass panel provided with simulated joints having an outer surface mounted in the support frame with an inner surface mounted adjacent to the inner surface of the first glass panel, and an inner grid formed of simulated muntins which fits adjacent to the second glass panel and is a mirror image of the simulated muntins adjacent to the first glass panel.




The preceding and further objects of the present invention will be appreciated by those of ordinary skill in the art from a reading of the figures and the detailed description of the preferred embodiment which follow, such description being merely illustrative of the present invention.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a front plan view of a decorative building unit simulating a multi-pane window according to the present invention;





FIG. 2

is a schematic, fragmentary cross sectional view of the decorative building unit taken along the line


2





2


of

FIG. 1

;





FIG. 3

is a schematic, fragmentary, cross sectional view of the decorative building unit taken along the line


3





3


of

FIG. 1

;





FIG. 4

is a schematic, fragmentary, cross sectional view of the decorative building unit illustrating the use of two glass panels;





FIG. 5

is a front plan view of a grid mounted on a decorative building unit adjacent a second glass panel;





FIG. 6

is a front plan view of a decorative building unit illustrating an alternative decorative design simulating a multi-pane window according to the present invention.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT




As seen in

FIG. 1

, the preferred embodiment of the present invention provides a decorative building unit


10


which includes a support frame


12


and a glass panel


22


. The support frame


12


is rectangular and is formed by a pair of opposed, spaced apart L-shaped side walls


14


and a pair of opposed, spaced apart L-shaped end walls


16


. Referring to

FIGS. 1 through 3

, L-shaped side walls


14


and end walls


16


form a recessed region


20


for receiving the glass panel


22


. Simulated muntins


18


extend between and are suitably attached to the side walls


14


and simulated muntins


19


extend between and are suitably attached to the end walls


16


. When the side walls


14


, end walls


16


, and simulated muntins


18


and


19


are attached together, the glass support frame


12


is completely assembled and ready to receive a glass panel


22


in recessed region


20


.




The frame may be wooden or metal, and the simulated muntins may be wooden, metal or plastic. The simulated muntins are preferably pre-assembled as a grid and attached to the frame. The simulated muntins may be attached to the frame by nailing, gluing, tacking, screwing, or any other suitable attachment means.




Referring again to

FIG. 1

, glass panel


22


has a pair of spaced apart side edges


24


and a pair of spaced apart end edges


26


. The glass panel


22


has a shape that corresponds to the shape of the recessed region


20


. As seen in

FIGS. 2 and 3

, in order to simulate a multi-pane glass window or door, glass panel


22


further includes beveled regions extending between the side edges


24


and end edges


26


. These beveled regions may comprise a single shallow groove


28


, particularly where adjacent a top or end. Alternatively, and preferably for the central area, the beveled regions comprise two shallow, spaced apart grooves


29


. Each groove


28


,


29


includes a first wall


28


A,


29


A extending from a first peripheral edge


22


A of glass panel


22


to a groove bottom apex


28


B,


29


B, and a second wall


28


C,


29


C extending from groove bottom apex


28


B


29


B to a second peripheral edge


22


B. As previously stated, the grooves are shallow with the long wall


28


C,


29


C being formed at an angle of at least 2° (and preferably from about 6 to 10°) with the surface of the glass, and the short wall


28


A,


29


A being formed at an angle of 45 to 68° with the surface. Greater angles for the short wall would be preferable, but the glass tends to chip if too great an angle is attempted with conventional grinding wheels. Also, the depth of grooves


28


,


29


should not exceed 30% of the thickness of the glass. The parallel grooves


29


define at least one platform


30


therebetween. The single shallow grooves


28


define a platform


31


between the grooves


28


and the end and side edges


24


,


26


of glass panel


22


. Once the selected number of beveled regions


28


,


29


have been formed in glass panel


22


, glass panel


22


is ready to be received in glass support frame


12


.




As seen in

FIGS. 2 and 3

, the size and spacing of end and side walls


14


,


16


, simulated muntins


18


,


19


, grooves


28


,


29


, and platforms


30


is designed such that when glass panel


22


is placed in recessed region


20


of glass support frame


12


, the simulated muntins


18


and


19


and platforms


30


will align with each other to simulate a multi-paned beveled window or door. That is, the size and shape of the platforms


30


defined by the beveled regions


28


,


29


substantially matches the size and shape of the simulated muntins


18


and


19


.




As seen in

FIG. 3

, securing hardware


32


is located around the rear peripheral edges of side walls


14


and end walls


16


to hold glass panel


22


securely in place. Any suitable securing means


32


well known in the art may be used for holding glass panel


22


in place. Depending up the specific application envisioned for the decorative building unit, it may be desirable to place spacer members


34


between glass panel


22


, end and side walls


14


,


16


, and simulated muntins


18


,


19


to eliminate any potential rattle due to small movements between the glass panel


22


and the glass support frame


12


. Any desirable and suitable spacer member material such as rubber or foam may be used. The spacer material may be held in place by being adhered either to the frame or to the glass panel. In either case, the spacer member should be sized and shaped so as to be invisible to the user.




Depending upon the desired application, such as an entry door, it may be desirable to install a second glass panel


40


such that the assembled building unit simulates a multi-pane beveled door when viewed from either the outside or inside. As seen in

FIG. 4

, a second glass panel


40


is mounted in glass support frame


12


such that it is laterally spaced apart from glass panel


22


. A suitable spacer member


44


such as rubber, foam, wood, or plastic may be used to separate glass panels


22


and


40


and to eliminate potential rattle between glass panels


22


and


40


. The spacer member


44


should be sized and shaped so as to be invisible to the user and such that glass panels


22


,


40


simulate a single glass panel beveled on both sides. Grooves


52


,


54


and platforms


56


formed in glass panel


40


are identical grooves


28


,


29


and platforms


30


formed in glass panel


22


such that the two glass panels


22


,


40


mirror each other. As seen in

FIGS. 4 and 5

, a grid assembly having simulated muntins


46


,


48


is positioned adjacent glass panel


40


to assist in holding glass panel


40


in support frame


12


. Simulated muntins


46


,


48


and platforms


56


align with each other to simulate a multi-pane beveled window or door when viewed from the second glass panel


40


side. Again, any suitable securing means


32


may be used to hold both panels


22


,


40


and grid


50


in place in support frame


12


.




The shape of simulated muntins


18


,


19


,


46


, and


48


need not be limited to straight, parallel sections. Other designs may also be used in which beveled regions


20


are formed in glass panel


22


to enhance the architectural and aesthetic features of the building unit. One such building unit


60


is shown in

FIG. 6. A

glass support frame


61


includes a peripheral support frame. Straight simulated muntins


62


,


64


extend between and are attached to the side walls


68


and end walls


66


. An oval frame member


70


is attached to simulated muntins


62


,


64


. Beveled regions


72


,


74


, and


76


are formed in glass panel


78


. Glass panel


78


is then mounted in glass support frame


61


.




As will be apparent, the present invention provides a convenient and cost-effective way in which to provide a building unit that simulates a much more expensive multi-pane beveled window or door. Since the glass support frame and beveled glass panel may be made separately and subsequently assembled together, the present invention permits the manufacture of components to be performed at different locations and by different suppliers. Further, the design permits a simple, quick final assembly of components, without the need for using adhesives or other bonding materials which often require significant curing times.




Certain modifications and improvements will occur to those skilled in the art upon reading the foregoing description. It should be understood that all such modifications and improvements have been omitted for the sake of conciseness and readability, but are properly within the scope of the following claims.



Claims
  • 1. A decorative building unit simulating a multi-pane beveled glass window or door, comprising:a) a glass support frame comprising: a peripheral support frame having a pair of opposed spaced apart side walls and a pair of opposed spaced apart end walls, each side and end wall having an L-shaped cross-section; at least one simulated muntin extending between and attached to said pair of side walls and at least one simulated muntin extending between and attached to said pair of end walls; said L-shaped side and end walls forming a recessed region for receiving a glass panel; b) a first glass panel having an outer surface mounted in said recessed region, said first glass panel having a pair of spaced apart side edges and a pair of spaced apart end edges and corresponding in size and shape to said recessed region of said frame; at least one simulated joint formed in said outer surface and extending between said side edges of said first glass panel, and at least one simulated joint formed in said outer surface and extending between said end edges of said first glass panel; each of said simulated joints comprising: i) at least two shallow spaced apart parallel grooves formed in said outer surface; ii) a platform defined between said two spaced grooves; beveled regions formed in said outer surface of said first glass panel extending along each said side edge and each said end edge; each said beveled region comprising: i) a single shallow groove formed in said outer surface; ii) a platform defined between said groove and said edge of said glass panel; c) wherein the size and spacing of said simulated muntins and said grooves and platforms of said simulated joints are such that, when said first glass panel is received in said recessed region, said simulated muntins align with said platforms of said simulated joints to simulate the appearance of a multi-pane beveled glass window or door; and d) a means for securing said first glass panel in said frame.
  • 2. The decorative building unit of claim 1 wherein each of said grooves formed in said outer surface of said glass panel includes a first wall extending from a first peripheral edge to a groove bottom apex and a second wall extending from said apex to a second peripheral edge, said second wall having a width greater than a width of said first wall.
  • 3. The decorative building unit of claim 2 wherein said groove first wall width is no greater than about 15 percent of said second wall width.
  • 4. The decorative building unit of claim 2 wherein each said groove second wall forms an angle with said outer surface of said glass panel of at least 2degrees.
  • 5. The decorative building unit of claim 2 wherein each said groove first wall forms an angle with said outer surface of said glass panel of at least 45 degrees.
  • 6. The decorative building unit of claim 1 wherein each said glass panel groove has an overall width of from about 5 to about 30 millimeters.
  • 7. The decorative building unit of claim 6 wherein each said glass panel groove has an overall width of from about 10 to about 20 millimeters.
  • 8. The decorative building unit of claim 1 wherein said glass panel has a thickness of from about 3 to about 6 millimeters.
  • 9. The decorative building unit of claim 8 wherein the depth of each said glass panel groove does not exceed 30 percent of the thickness of said glass panel.
  • 10. The decorative building unit of claim 1 wherein at least one spacer member is disposed between said glass support frame and said glass panel.
  • 11. The decorative building unit of claim 3 further including a second glass panel unit, comprising:a) a second glass panel having an outer surface mounted in said frame recessed region and laterally spaced apart from said first glass panel, said second glass panel having a pair of spaced apart side edges and a pair of spaced apart end edges and corresponding in size and shape to said recessed region of said frame; at least one simulated joint formed in said second glass panel outer surface and extending between said side edges of said second glass panel and at least one simulated joint formed in said second glass panel outer surface and extending between said end edges of said second glass panel, said simulated joints corresponding in size, shape, and position to said simulated joints of said first glass panel; each of said simulated joints comprising: i) at least two shallow spaced apart parallel grooves formed in said outer surface; ii) a platform defined between said two spaced grooves; beveled regions formed in said outer surface of said second glass panel extending along each said side edge and each said end edge; each said beveled region comprising: i) a single shallow groove formed in said outer surface; ii) a platform defined between said groove and each said side and end edge of said glass panel; b) a grid comprising: i) a pair of opposed spaced apart side walls and a pair of opposed spaced apart end walls; ii) at least one simulated muntin extending between and attached to said pair of side walls and at least one simulated muntin extending between and attached to said pair of end walls; wherein said grid corresponds in size and shape to said recessed region of said frame; c) wherein the size and spacing of said muntins and said grooves and platforms is such that, when said second glass panel is received in said recessed region, said simulated muntins of said grid align with said platforms; and d) a means for securing said second glass panel and said grid in said frame.
  • 12. The decorative building unit of claim 11 wherein each said groove second wall forms an angle with said outer surface of said glass panel of at least 2 degrees.
  • 13. The decorative building unit of claim 11 wherein each said groove first wall forms an angle with said outer surface of said glass panel of at least 45 degrees.
  • 14. A decorative building unit simulating a multi-pane beveled glass window or door, comprising:a) a glass support frame comprising: a peripheral support frame having a pair of opposed spaced apart side walls and a pair of opposed spaced apart end walls; at least one simulated muntin extending between and attached to said pair of side walls and at least one simulated muntin extending between and attached to said pair of end walls; b) a single glass panel having an outer surface mounted on said frame, said glass panel having a pair of spaced apart side edges and a pair of spaced apart end edges; at least one simulated joint extending between said side edges and at least one simulated joint extending between said en d edges; each of said simulated joints comprising: i) at least two shallow spaced parallel grooves formed in said outer surface; ii) a platform defined between said two spaced grooves; beveled regions formed in said outer surface of said first glass panel extending along each said side edge and each said end edge; each said beveled region comprising: i) a single shallow groove formed in said outer surface; ii) a platform defined between said groove and said edge of said glass panel; c) wherein the size and spacing of said simulated muntins and said grooves and platforms of said simulated joints are such that, when said glass panel is mounted against said glass support frame, said simulated muntins and said platforms of said simulated joints align with each other to simulate said multi-pane beveled glass window or door; and d) a means for securing said glass panel on said frame.
  • 15. The decorative building unit of claim 14 wherein each side and end wall of said peripheral support frame have an L-shaped cross section.
  • 16. The decorative building unit of claim 15 wherein said L-shaped side and end walls form a recessed region for receiving a glass panel.
  • 17. The decorative building unit of claim 16 wherein said glass panel has an outer surface mounted in said frame recessed region.
  • 18. The decorative building unit of claim 14 wherein each of said grooves formed in said outer surface of said glass panel includes a first wall extending from a first peripheral edge to a groove bottom apex and a second wall extending from said apex to a second peripheral edge, said second wall having a width greater than a width of said first wall.
  • 19. The decorative building unit of claim 18 wherein said groove first wall width is no greater than 15 percent of said second wall width.
  • 20. The decorative building unit of claim 18 wherein each said groove second wall forms an angle with said outer surface of said glass panel of at least 2degrees.
  • 21. The decorative building unit of claim 18 wherein each said groove first wall forms an angle with said outer surface of said glass panel of at least 45degrees.
  • 22. The decorative building unit of claim 14 wherein each said glass panel groove has an overall width of from about 5 to about 30 millimeters.
  • 23. The decorative building unit of claim 22 wherein each said glass panel groove has an overall width of from about 10 to about 20 millimeters.
  • 24. The decorative building unit of claim 14 wherein said glass panel has a thickness of from about 3 to about 6 millimeters.
  • 25. The decorative building unit of claim 24 wherein the depth of said glass panel grooves does not exceed 30 percent of the thickness of said glass panel.
  • 26. The decorative building unit of claim 14 wherein at least one spacer member is disposed between said glass support frame and said glass panel.
  • 27. A decorative building unit simulating a multi-pane window or door, comprising:a) a glass support frame comprising: a peripheral support frame having a pair of opposed, spaced apart side walls and a pair of opposed, spaced apart end walls; at least one simulated muntin extending between and attached to said pair of side walls and at least one simulated muntin extending between and attached to said pair of end walls; b) a single glass panel having an outer surface mounted on said frame, said glass panel having a pair of spaced apart side edges and a pair of spaced apart end edges; at least one simulated joint comprising i) at least two shallow spaced apart grooves formed in said outer surface; ii) a platform defined between said two spaced grooves c) wherein the size and spacing of said simulated muntins and said grooves and platforms of said simulated joints are such that, when said glass panel is secured against said glass support frame, said simulated muntins and said platforms of said simulated joints align with each other to simulate said multi-pane beveled glass window or door; and d) a means for securing said glass panel on said frame.
  • 28. The decorative building unit of claim 27 wherein side walls and said end walls have an L-shaped cross section.
  • 29. The decorative building unit of claim 28 wherein said L-shaped side walls and end walls form a recessed region and said glass panel is received in said recessed region.
  • 30. The decorative building unit of claim 27 wherein each of said grooves formed in said outer surface of said glass panel includes a first wall extending from a first peripheral edge to a groove bottom apex and a second wall extending from said apex to a second peripheral edge, said second wall having a width greater than a width of said first wall.
  • 31. The decorative building unit of claim 30 wherein said groove first wall width is no greater than 15 percent of said second wall width.
  • 32. The decorative building unit of claim 30 wherein each said groove second wall forms an angle with said outer surface of said glass panel of at least 2 degrees.
  • 33. The decorative building unit of claim 30 wherein each said groove first wall forms an angle with said outer surface of said glass panel of at least 45 degrees.
  • 34. The decorative building unit of claim 27 wherein each said glass panel groove has an overall width of from about 5 to about 30 millimeters.
  • 35. The decorative building unit of claim 34 wherein each said glass panel groove has an overall width of from about 10 to about 20 millimeters.
  • 36. The decorative building unit of claim 27 wherein said glass panel has a thickness of from about 3 to about 6 millimeters.
  • 37. The decorative building unit of claim 36 wherein the depth of said glass panel grooves does not exceed 30 percent of the thickness of said glass panel.
  • 38. The decorative building unit of claim 27 wherein at least one spacer member is disposed between said glass support frame and said glass panel.
US Referenced Citations (14)
Number Name Date Kind
3411258 Kessler Nov 1968
4145858 Dovman Mar 1979
4437284 Cribben et al. Mar 1984
4488919 Butler Dec 1984
4813990 Thorn Mar 1989
4970840 Ouellette et al. Nov 1990
5018330 Lewkowitz May 1991
5086596 Schlyper Feb 1992
5487245 Dazo et al. Jan 1996
5555654 Hermann Sep 1996
5840391 Eichhorn et al. Nov 1998
5853835 Leniton Dec 1998
5853852 Eichhorn Dec 1998
5983593 Carbary Nov 1999