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|United States Patent
, et al.
July 13, 1971
AUTOMATIC TENSIONING BAR FOR PORTABLE PICTURE SCREENS
A vertically extending stretch bar having toggle arrangement therein on the
rear of a hanging projection screen to automatically tension the screen
surface when the screen is in fully extended position and hidden from view
behind the screen case when the screen is rolled up in the case.
Potter; Fred S. (Warsaw, IN), Maxson; Walter (Warsaw, IN) |
Da-Lite Screen Company, Inc.
March 3, 1969|
|Current U.S. Class:
||160/24 ; 160/351|
|Current International Class:
||G03B 21/56 (20060101); G03B 21/58 (20060101); G03b 021/58 ()|
|Field of Search:
U.S. Patent Documents
Bell; J. Karl
1. In a wall or ceiling hang-type portable projection screen a housing, a spring roller mounted in said housing, a screen fabric mounted on and rolled up on said spring roller, a slat
anchored to the free end of said screen fabric, a saddle mounted on said slat, and a bail mounted on the saddle medially of the ends of the slat; in combination with an automatic tensioning and stretch means for the screen fabric when in open position
and positioned on the rear of said housing, said means comprising a pair of tubes pivotally joined together in substantial end-to-end relationship by a link joint, the free end of one of the tubes pivotally secured to the rear of said casing, medially of
the ends thereof, one end of a gooseneck bar anchored to the free end of the other tube, the other end of the bar being provided with a cylindrical groove to loosely and pivotally seat the bail and provide means to anchor a handle thereon, whereby when
said screen fabric is withdrawn from the case the tubes and link will automatically move to a position offset from the vertical axis formed by the tube pivot on the casing and bail slat to lock and tension the screen fabric.
2. The device according to claim 1 wherein the two tubes are folded in substantially parallel spaced relationship behind said housing when the screen fabric is positioned therein in inoperative position, and means on said saddle to retain said
tubes in such position.
3. In a wall or ceiling hang-type portable projection screen having a case, carrying a spring roller for winding the screen fabric thereon, a slat for the free end of the fabric, a saddle mounted on said slat, having a bail positioned thereon
medially of the ends of said saddle; in combination with a tensioning stretch and lock bar, said stretch bar comprising a pair of tubes, a short U-shaped link for pivotally securing said tubes together in substantially end-to-end relationship, means on
said case medially of the ends thereof pivotally securing the free end of one of said tubes to said case, offset means on the free end of said other tube pivotally securing said tube to said bail, a handle on the free end of said last-mentioned means for
withdrawing said fabric from said case and moving said link and tubes in an offset position from the vertical when the fabric is withdrawn from said case, and returning said link and tubes in folded position behind said case when the fabric is rewound in
the case, and hook means on said saddle to retain said tubes in folded position against said case when said fabric is rewound on said spring roller.
4. The device according to claim 3 wherein the means on the free end of said other tube is a rectangular in cross section bar anchored at one end to said other tube, and bent sidewardly and downwardly away from said tube, and terminating at
right angles to said tube, a groove in said bar for pivotally retaining said bail, and the handle secured to the free end of said bar.
5. In a ceiling or wall hang-type projection screen comprising a case, a spring roller secured in said case, a screen fabric wound on said roller, a slat secured to the free end of said screen fabric, a saddle on said slat and a bail secured
medially to said saddle; in combination with concealed stretch, tension and locking device mounted in the rear of said case, comprising a pair of tubes, a U-shaped in cross section, toggle link pivotally securing said tubes together, a center band on
said case positioned medially of the ends of said case and having an offset portion therein, the free end of one of said tubes pivotally secured to said offset portion of said case, a bar having one end secured to the free end of said other tube and
having a 45.degree. bend substantially medially of its ends in a downwardly and sidewardly direction, and beyond said bend said bar is bent at right angles and positioned in horizontal plane terminating beyond said slat, a handle affixed to the end of
the free end of said bar, a cylindrical groove in said bar for the loose reception of said bail to form a pivot.
6. The device of claim 5 wherein the closed portion of said U-shaped link is provided with inwardly extending detents adjacent each end of said link to space said tubes away from said closed wall of said link.
7. The device of claim 6 wherein a clip is anchored to said saddle for supporting said tubes adjacent the rear of said case when in inoperative position.
SUMMARY OF THE INVENTION
The provision of a stretch bar incorporated as a permanent part of a hanging-type projection picture screen wherein when the screen fabric is fully wound on its spring roller, i.e., in nonoperative position, the stretch bar will be substantially
hidden from view behind the screen casing and when the screen fabric is in operative position, i.e., fully extended, the stretch bar will be out of sight behind the screen, and will automatically tension the screen fabric, and lock the fabric in extended
position, and will prevent the fabric from being pulled off the spring roller. The provision of a stretch bar in which both distal ends are pivotally secured, one end to the case, medially of its ends, and the other end to the saddle and medially
thereof. The provision of a stretch bar wherein the same is in two pieces with the end loosely held together by a short link or toggle to hold the screen fabric in fully stretched position under tension and in locked position, and handle means to
withdraw the fabric from inoperative position to operative and vice versa, and simultaneously operate the stretch bar to lock and unlock the toggle.
FIG. 1 is a rear elevation of a portable screen in inoperative position and showing our new
FIG. 2 is a rear elevation of the screen in fully extended and locked position.
FIG. 3 is a rear elevation showing the screen fabric partially rolled up in the case.
FIG. 4 is an enlarged perspective view of one end of the casing with parts broken away.
FIG. 5 is a perspective view of the link or toggle joint with parts broken away.
FIG. 6 is a perspective view of the handle shown secured to the screen when the screen fabric is fully extended with parts shown in phantom.
FIG. 7 is an enlarged elevational view of the stretch bar in fully extended position and with the toggle in over the center position, and with parts broken away.
FIG. 8 is a cross-sectional view taken on the line 8-8 of FIG. 7.
FIG. 9 is a cross-sectional view taken on the lines 9-9 of FIG. 7.
FIG. 10 is a cross-sectional view taken on the line 10-10 of FIG. 8.
FIG. 11 is a cross-sectional view taken on the line 11-11 of FIG. 1.
FIG. 12 is an end view taken on the line 12-12 of FIG. 2.
The screen casing 12 is the usual and customary one such as shown in U.S. Pat. No. 2591685 issued Apr. 8, 1952, to DuMais, having a spring roller on which the screen fabric 14
is wound. The free end of the fabric is anchored to a slat 16 and a spring steel tensioning saddle 18 is anchored adjacent each end to the slat 16. Medial of the ends of the saddle 18 is the usual bail 20. A hanging bracket 21 is secured to each
closure cap 13. All the above is generally found in wall or ceiling hang-type screens on the market today.
The present invention is directed to the toggle-type bar to tension the screen fabric and lock the spring roller from further rotation, and the components associated therewith.
The stretch bar comprises upper and lower tubes 22 and 24. The upper end of tube 22 is enveloped in a short tube 26 (See FIG. 8) and both are pivotally and loosely anchored by means of a bolt 28 to the usual center band 30 which is provided with
an offset portion 32 to accommodate the head 34 of bolt 28 which is welded to the center band.
The lower end of tube 24 is provided with an offset or goose neck bar 36, rectangular in cross section, the upper end being telescoped interiorly of the lower portion of the tube 24 and riveted thereto in fixed position. The bar 36, a shown in
FIG. 7, extends downwardly from tube 24 and sidewardly at about 45.degree. to the axis of the tube 24. The distal end portion 36' lies in a plane normal to the axis of tube 24 and is twisted about 90.degree. to a diamond-like shape (See FIG. 6).
A handle 38 is anchored to the distal end 36' of the bar 36 as clearly shown in FIGS. 6 and 9. In FIG. 6 it is to be noted that the upper surface of the handle is broad and flat for ease in operating the stretch bar. At 40 the surface of the
handle is imprinted with the words "press to lock" an at 42 the words "press to release," the purpose of which will hereinafter be described.
It is to be especially noted that the handle 38 is provided with an integrally formed, rectangular in cross section, sleeve 44 of a size and shape to receive the free end of the bar 36'. The bar is inserted into the sleeve until it reaches the
boss 46, and is held therein by a screw 48 which is anchored in an appropriate threaded aperture 50 in the bar portion 36'. Thus the handle 38 rotates 90.degree. from the closed position of the screen (See FIG. 1) to the fully opened position of FIG.
The bar 36 is provided with a cylindrical groove 37 into which the bail 20 is loosely seated to provide a pivot.
The two tubes 22-24 are loosely held together by a toggle or link 52, of U-shape cross section (See FIG. 10), which embraces the ends of the tubes as clearly shown in FIGS. 5, 7 and 8. A headed pin 54 extends loosely thru the sidewalls 56 and 58
of the toggle 52 and thru appropriate aligned apertures 22' in the upper end 66 of the lower tube 24 to form a loose pivot. The upper end of toggle 52 as viewed in FIGS. 7 and 8 is provided with spaced apertures 59 in wall 56 and complimentary apertures
60 in wall 58.
The lower end 64 of tube 22 (as viewed in FIG. 8) is pivotally secured to the link 52 by headed pin 54' extending thru appropriate apertures 60 in link 52 and offset apertures 24' adjacent end of tube 22. Each pin 54, 54' is retained in position
by a speed nut 62. The numerous apertures in the walls 56--58 are of course for adjustment purposes of the arms 22, 24 to compensate for production variations to increase or decrease the tension on the fabric that might be desired. Also, there may be
variations in fabric length with time and usage.
Once the adjustment is made the tubes 22, 24 and link 52 will extend to a fixed length each time they are extended.
It is to be especially noted that the apertures 22' and 24' adjacent the ends of tubes 22 and 24 respectively, are positioned closer to one end wall then the other, while the apertures 59--60 in the sidewalls 56--58 are positioned substantially
medially of the sidewalls 68 and 68' whereby the ends 64 and 66 of tubes 22--24 will readily clear the inner surface of wall 68 when the tubes are moved from the position shown in FIG. 1 to that shown in FIG. 2.
As shown in FIG. 2 the toggle or link 52 and the tubes 22-24 extend downwardly from the pivot 28 and offset from the vertical axis extending between pivot points 28 and 20. This is the result of the goose neck formation in bar 36.
In operation the screen casing is hung on a wall by any suitable means using the figure "8" shaped clip 70, or anchored to the ceiling by the clip 70 and chain 72. If the handle 38 is above reach the pull cord 74 may be employed.
By pulling downwardly on cord 74 or by the handle 38 the screen fabric 14 will be unwound from its roller. Further downward pull will position the screen fabric 14 and tubes 22--24 and toggle 52 in the position shown in FIG. 3. Further downward
pressure is exerted on the handle at 40 until the tubes 22--24 and toggle joint 52 are offset from the vertical axis connecting the pivot points formed by bolt 28 and bail 20. This will now limit the downward pull of the screen fabric and forever
prevent tearing the fabric 14 from its spring roller. Further the fabric is both properly tensioned and the spring roller locked in viewing position thus preventing further rotation of the spring roller when the fabric is unrolled the desired length.
Former tensioning devices for the screen fabric failed to provide means for preventing either over or under tensioning or the screen fabric. This had been solved by this invention for the first time.
To raise the screen, slight pressure is exerted on the handle at 42. This will cause the toggle joint 52, as well as tubes 22 and 24, to move to the right (as shown in FIG. 3) in one motion from that shown in FIGS. 2 and 7 and the spring roller
will then take over and the entire fabric 14 will be rewound on the spring roller and move the tubes from the position shown in FIG. 3 and finally to that shown in FIG. 1.
In order to hold the tubes 22--24 in place behind the screen casing 12, a C-shaped clip 76 is secured to the saddle to automatically engage tube 24 just prior to the complete rewinding of the fabric 14 on its spring roller. Without this clip 76
the weight of the tubes 22-24 and link 52 would cause appreciable sideward thrust on the saddle 18, tending to make the fabric 14 roll up crookedly on its spring roller. Thus the clip 76 supports and retains the tubes 22--24 adjacent to the rear of the
case 12 when the screen is not in use (See FIG. 1).
Also the wall 68 of the U-shape link 58 is provided with detents 68, 80 extending inwardly into the interior of the inside surface thereof to space the tubes 22, 24 respectively away from the inner face of wall 68, and retain the tubes 22, 24 and
link 52 in a straight line when the screen fabric is fully extended. Also upon closing the screen the over center apertures 22' and 24' and pins 54, 54' through apertures 59 and the detents 78 and 80 prevent the angle between the link 52 and the tube 24
from closing very little less than 90.degree. during roll up of the fabric 14 (See FIG. 3).
Thus the present invention will allow the screen fabric to be withdrawn, stretched and locked in one continuous movement. The fabric 14 cannot be under or over stretched as is possible with screens on the market.
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