US3567168A

US3567168A - Overhead projection screen holder

Info

Publication number: US3567168A
Application number: US759109A
Authority: US
Inventors: Ambrose M Jennings
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-09-11
Filing date: 1968-09-11
Publication date: 1971-03-02
Anticipated expiration: 1988-03-02

Abstract

A holder for mounting a projection screen against a wall in such a manner that the top of the screen may be moved outwardly from said wall to incline the screen, said holder consisting of an arm adapted to lie vertically against a wall, a link pivoted at its upper end to said wall above said arm, and at its lower end to the midpoint of said arm, on horizontal axes parallel to the wall, whereby said arm may be inclined outwardly from the wall with its lower end engaging the wall, the upper edge of the screen being attached to the upper end of said arm, and a generally vertical bar attached to the lower end of said arm and extending downwardly therefrom, whereby said arm may be manipulated, the lower edge of said screen being attachable to the lower end of said bar.

Description

United States Patent [72] Inventor Ambrose M.Jennings Box 176, Basehor, Kans. 66007 [21] Appl.No. 759,109 [22] Filed Sept.11, 1968 [45] Patented Mar. 2, 1971 [54] OVERHEAD PROJECTION SCREEN HOLDER 8 Claims, 5 Drawing Figs.

[52] U.S.Cl 248/284, 160/23 [51] 1nt.Cl ..G03b 21/56 [50] Field of Search 248/284, 286, 293, 291, 324, 489, 495, 496; 160/23, 24, 29;

. 35/63 v 56] References Cited UNITED STATES PATENTS 2,229,472 1/1941 Raven l60/24X 2,825,152 3/1958 Baylon 35/63 3,309,049 3/1967 Albee 160/24X FOREIGN PATENTS 676,403 2/1930 France Primary Examiner-Roy D. Frazier Assistant Examiner-J. Franklin Foss Attorney-John A. Hamilton ABSTRACT: A holder for mounting a projection screen against a wall in such a manner that the top of the screen may be moved outwardly from said wall to incline the screen, said holder consisting of an arm adapted to lie vertically against a wall, a link pivoted at its upper end to said wall above said arm, and at its lower end to the midpoint of said arm, on horizontal axes parallel to the wall, whereby said arm may be inclined outwardly from the wall with its lower end engaging the wall, the upper edge of the screen being attached to the upper end of said arm, and a generally vertical bar attached to the lower end of said arm and extending downwardly therefrom, whereby said arm may be manipulated, the lower edge of said screen being attachable to the lower end of said bar.

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()VERHEAD PRQJEQTION SCREEN HOLDER This invention relates to new and useful improvemenm in projection screen holders, and has particular reference to pro jection screens mounted in overhead positions.

In classrooms, it is common practice for an instructor to remain seated at his desk at the front of the classroom, with a slide, movie or other projector on the desk before him and to project pictures or other instructional material rearwardly and upwardly over his head to a screen mounted high on the room wall behind him. This allows him to lecture from the front of the room, and to control and operate the projector at the same time. Projectors suitable for this purpose are commercially available. However, this type of projection is subject to certain difficulties if the screen is suspended vertically against the wall in the usual manner. Since the image is then projected upwardly at an acute angle to the screen surface, the top portion of the screen is farther from the projector than the lower portion of the screen, and the top portion of the projected image is wider than the lower portion of theimage; This type of distortion is commonly known as a keystone effect, and is of course highly objectionable. Also, since the upper and lower portions of the screen are at different distances from'the projector, it is often impossible to keep the entire projected image clear and sharply focused.

Certain types of overhead projection screen holders have been proposed for overcoming the across-the-room and focusing difficulties, by permitting inclining of the screen so as to be generally normal to the axis of the projected beam, but all of these within my knowledge have also-been subject to certain objectionable features, in that they have been relatively complicated and expensive structures, or .that they require the screen to be set at all times well out from the wall so as to be in the way and to constitute an eyesore, or that they are difficult to operate or manipulate by an operator standing on the floor, since the screen is preferably positioned substantially at ceiling level and classroom ceiling are often eleven feet. or more above the floor. Also, screens mounted at this high elevation are not generally desirable for use with ac'ross-the-room projectors, which generally require a lower screen, so that the use of such an across-the-room projector generally requires a separate screen. r

Accordingly, the object of the present invention is the provision of an overhead projection screen holder which eliminates all of the above enumerated objectionable features of previous holders, in that, it not only permits inclination of the screen to eliminate keystoning and focusing difficulties, but also is extremely simple and economical of structure, permits the screen to be stored flat against the wall, or even reeled up in a reel case, when not in use, which is easily operable by an operator standing on the floor, and which permits lowering of the screen to an elevation suitable for use with across-the-room projectors.

In summary, these objects are accomplished by a screen holder consisting of an arm which is normally verticaland lies flat against the wall with-its upper end substantially 'at the ceiling level, the screen case extending horizontally and being affixed to the upper end of saidarm so that the screen may be extended downwardly therefroma link pivoted at its upper end to the ceiling or wall and at its lower end to the midpoint of said arm,'whereby the upper end of said arm maybe moved outwardly from the wall by pushing upwardly on the lower end thereof, and a pusher-bar adapted to be attached to the lower end of said arm and to lie vertically against the wall, whereby said arm may be manipulated, the lower edge of said screen being attachable to the lower end of said pusher bar. When detached from the arm, the pusher bar may be; utilized as a grapple to reach and extend the screen from its case. The arm may be concealed by a decorative plaque secured thereto when the screen is not in use. Also, the arm may be reversed by pivoting it on said link to bring the screen case to the lower end thereof, so that the screen may be extended for use at a lower elevation for use with across-the-room projectors.

With these objects in view as well as other objects which will appear in the course of the specification, reference will be had to the accompanying drawing, wherein:

FIG. I. is a front elevational view. partially broken away, of an overhead projection screen holder embodying the present invention, operatively mounted on a classroom wall, with a screen case mounted on the holder, but with the screen retracted into said case;

FIG. 2 is a fragmentary sectional view taken on line II--II of F 1G. 1, with parts left in elevation;

FIG. 3 is a view similar to FIG. 2, but with the screen extended and inclined for use with an overhead projector;

FIG. 4. is a view similar to. FIG. 2 but with the screen positioned for use with an across-the-room projector; and

FIG. 5 is a reduced sectional view taken on line V-V of FIG. 1, showing the relationship of the screen to an overhead projector.

1 Like reference numerals apply to similar parts throughout the several views, and referring principally to FIG. 5, the numeral 2 applies to a projector resting on the instructor's desk 4 at the front of a classroom having a front wall 6, ceiling 3 and floor 10, said projector being operable to project an image of instructional material to a projection screen 12 disposed high on wall 6. Thus the instructor may sit at his chair 14 before the desk, facing his class, and simultaneously operate the projector, deliver his lecture, and refer by pointer or the like to details of the projected image. The screen 12, as shown, is pliable and is wound on a spring reel mounted in a rigid cylindrical case l6, so that it maybe extended downwardly from said case by pulling downwardly thereon in the manner of an ordi narywindow shade. The spring reel is also ordinarily provided with a ratchet mechanism for. retaining the screen releasably at any desired degree of extension from the case. This structure is common and well known in the art, and is therefore not shown. The screen is provided along its lower edge with a stiffening bar 15 provided at its midpoint with a pull loop 17 which may be grasped to extend the screen manually.

The screen holder forming the subject matter of the present invention'includes an arm 18 adapted normally to lie vertically against wall 6, with its upper end closely adjacent ceiling 8. As shown, said arm consists of a pair of parallel side rails 20 rigidly joined intermediate their ends by a block 22. Adjacent the lower end of the arm, a rod 24 extends transversely between and is affixed at its ends in side rails 20. Screen case 16 is affixed to the upper end of arm 18, at the side thereof away from wall 6, as by screws 26. Said screen case is disposed horizontally and parallel to wall 6.

- Arm 18 is supported by a link 28 of inverted U-form. The arms 30 of said link are engaged pivotally. in side rails 20 of arm 18, at the midpoint of said arm, on a horizontal transverse axis, these pivotal connections being indicated at 32, and the base portion 34 of said link, which is parallel to the axis of pivots 32, is engaged pivotally in a pair of hooks 36 fixed in a bar 38;, said bar being affixed towall 6, at its juncture with ceiling 8, as by screws 40. When'the screen 12 is retracted within its case 16, as shown in FIGS. 1 and 2, arm 18 of course extends well below case 16 and would be unsightly when the screen is not in use, if means were not provided to conceal it. For this purpose, there is provided a planar plaque 42 affixed to the forward side of arm 18. Horizontally, this plaque may be of any desired width, while vertically it extends from a point just below screen case 16 to a point just above crossrod 24$ of the arm. Said plaque may carry a picture or other decorative matter on its outer surface. i

The screen holder also includes an elongated pusher bar or lever 44 adapted to be positioned between side rails 20 of arm 13, parallel therewith, and to extend beneath the lower end of said arm as shown in FIG. 1. Said pusher bar is provided intermediate its ends with a forwardly opening notch 46 adapted to be engaged over crossrod 24 of arm 18, and carries at its upper end of roller 48 rotatable on a horizontal transverse axis and adapted to move in rolling contact with room wall 6. At its lower end, bar 44 has a hook 50 affixed thereto.

When the screen is not in use, the parts have the position shown in FIGS. 1 and 2, except that at this time pusher bar 44 is normally detached from rod 24 and laid aside. If it were not, it would extend downwardly overthe blackboard of the classroom, said blackboard being indicated at 52, which would of course be objectionable. To position the screen for use, the operator first takes pusher bar 44, reversed so that hook 50 thereof is uppermost, and reaches upwardly to engage said hook in pull loop 17 of the screen, then pulls downwardly to extend screen 12 from its case 16. The length of the pusher bar is such that this operation may be performed easily by a person of ordinary height, even if screen case 16 is perhaps eleven feet above the floor. The operator then reverses the pusher bar so that roller 48 thereof is uppermost, and engages notch 46 thereof over crossrod 24 of arm 18, as shown.

The operator then pulls the lower end of pusher bar 44 slightly outwardly from wall 6, whereby said bar acts as a lever to move the lower end of arm 18 away from the wall and to press roller 48 against wall 6, and pushes upwardly on said pusher bar. This causes the upper end of arm 18, which is supported by link 28, to move outwardly from wall 6 as'shown'in FIG. 3. Outward initial movement, rather than movement toward and against wall 6, is assured by the weight of screen case 16 at the outer side of said am. The higher pusher bar 44 is raised, the more nearly arm 18 approaches a horizontal position. During this movement, the lower end of arm 18 is held out of engagement with wall 6 by the pusher bar, which is in turn supported against wall 6 by roller 48. Thus arm 18 does not slide frictionally on the wall, and scratching or marring of the wall which otherwise would occur is prevented. Also, it will be seen that while arm 18 is thus turned in a counterclockwise direction on link pivots 32 at this time, as viewed in FIG. 3, and that screen case 16 is thus lowered with respect to said pivots, nevertheless pivots 32 aresimultaneously elevated with respect to link pivot 34 bythe angular movement of the link. Thus screen case 16 remains at a generally uniform elevation regardless of the angle of arm 18. This is a distinct advantage over certain other screen holders, which permit adjustment of the screen angle only by bodily raising and lowering of the entire screen.

When arm 18 has been moved to the desiredangle, the lower end of pusher bar 44 is moved toward wall 6 to allow the lower end of arm 18 to engage wall 6 at the point 54 indicated in FIG. 3. The friction of this engagement, plus the counterclockwise (as viewed in FIG. 3) torque exerted on said arm by the weight of the screen and screen case, is ample to prevent slippage of the armagainst the wall, at all times after the arm has reached a certain minimum inclination relative to the wall, so that the arm remains fixed in the adjusted position. The depth of notch 46 of bar 44 must of course be sufficient to allow contact of arm 18 with wall 6 without obstruction by bar 44.

The pull loop 17 of the screen is then engaged on hook 50 at the lower end of pusher bar 44, and the screen is ready for use, supported at the proper angle for use with projector 2. If the screen is slack at this time, due to inaccurate original extension thereof from its case 16, it may be tightened by a slight pull on its lower edge to release the ratchet mechanism of the spring reel in case 16, whereupon the screen is tightened and held taut by the reel. Alternatively, screen pull loop 17 can be attached to hook 50 before arm 18 is tilted at all, so that pusher bar 44 is raised with the screen already attached thereto. Also, the angle of the screen can be adjusted at any time during use, by raising or lowering pusher bar 44.

As shown in FIG. 4, the present holder also permits lowering of the screen on wall 6, as may be desirable for use with across-the-room projectors. For this purpose, arm 18 is pivoted 180 on link pivots 32, so that crossrod 24 thereof is adjacent link pivot 34, and screen case 16 is at the lower end of the arm, against wall 6. Pusher bar 44 is not utilized in this case. Screen 12, when extended from its case 16, then depends vertically from the case, flush against wall 6, but with its operative surface still facing outwardly toward the room, as seen in FIG. 4.

While I have shown and described a specific embodiment of my invention, it will be readily apparent that many minor changes of structure and operation could be made without departing from the spirit of the invention as defined by the scope of the appended claims.

lclaim:

1. An overhead projection screen holder comprising:

a. an arm adapted normally to lie vertically against a room wall;

b. means for attaching the upper edge of a projection screen to the upper end of said arm, at the side thereof outward from said wall;

c. a normally vertical link pivoted at its lower end to said arm on a horizontal transverse axis intermediate the ends of the latter;

d. means for pivotally connecting the upper end of said link to said wall on a fixed horizontal transverse axis adjacent the upper end of said arm; and

e. means carried at the lower end of said arm for engaging the lower edge of said screen, .whereby as the lower end of said arm is raised upwardly along said wall, the upper end of said arm is moved outwardly from said wall and said screen is inclined outwardly and downwardly from said wall, the lower end of said arm being urged against said wall by the weight of said screen and being prevented from moving relative to said wall by its frictional engagement therewith.

2. An overhead projection screen holder as recited in claim I wherein said link is pivoted to said arm substantially at the midpoint of the latter, and wherein said arm is substantially twice the length of said link, whereby the upper end of said arm remains at a generally uniform elevation relative to said wall regardless of the degree to which said arm may be inclined.

3. An overhead projection screen holder as recited in claim 1 with the addition of means for moving the lower end of said arm vertically on said wall, said means comprising:

a. an elongated lever adapted to lie vertically against said wall and being pivoted intermediate its ends, on a horizontal transverse axis, to the lower end portion of said arm; and

b. a roller carried at the upper end of said lever for rotation on a horizontal transverse axis and adapted to engage said wall, whereby movement of the lower end of said lever outwardly from said wall will force the lower end of said arm away from said wall to be supported relative to said wall only through said lever and said roller.

4. An overhead projection screen holder as recited in claim 3 wherein the lower end of said arm extends downwardly beyond its pivotal connection to said lever to a sufficient degree to project beyond said lever toward said wall when said arm is inclined, so as to be engageable with said wall without interference by said lever.

5. An overhead projection screen holder as recited in claim 3 wherein said lever is detachably pivoted to said arm to be easily separated therefrom.

6. An overhead projection screen holder as recited in claim 4 wherein said arm is. provided adjacent its lower end with a horizontally and transversely extending crossrod engageable in a notch formed in said lever and opening outwardly from said wall, whereby said lever is detachably pivoted to said arm.

7. An overhead projection screen holder as recited in claim 3 having means at the lower end of said lever for releasably engaging the lower edge of said screen.

8. An overhead projection screen holder as recited in claim .6 for use in connection with a pliable projection screen normally reeled in a case carried at the upper end of said arm and extendable downwardly from said c se, and wherein said lever is provided at its lower end with a hook to which the lower edge of said screen is attachable when extended, said lever being reversible when detached from said arm for use with said hook uppermost as a tool to reach and extend said screen from said case.

Claims

1. An overhead projection screen holder comprising: a. an arm adapted normally to lie vertically against a room wall; b. means for attaching the upper edge of a projection screen to the upper end of said arm, at the side thereof outward from said wall; c. a normally vertical link pivoted at its lower end to said arm on a horizontal transverse axis intermediate the ends of the latter; d. means for pivotally connecting the upper end of said link to said wall on a fixed horizontal transverse axis adjacent the upper end of said arm; and e. means carried at the lower end of said arm for engaging the lower edge of said screen, whereby as the lower end of said arm is raised upwardly along said wall, the upper end of said arm is moved outwardly from said wall and said screen is inclined outwardly and downwardly from said wall, the lower end of said arm being urged against said wall by the weight of said screen and being prevented from moving relative to said wall by its frictional engagement therewith.

2. An overhead projection screen holder as recited in claim 1 wherein said link is pivoted to said arm substantially at the midpoint of the latter, and wherein said arm is substantially twice the length of said link, whereby the upper end of said arm remains at a generally uniform elevation relative to said wall regardless of the degree to which said arm may be inclined.

3. An overhead projectIon screen holder as recited in claim 1 with the addition of means for moving the lower end of said arm vertically on said wall, said means comprising: a. an elongated lever adapted to lie vertically against said wall and being pivoted intermediate its ends, on a horizontal transverse axis, to the lower end portion of said arm; and b. a roller carried at the upper end of said lever for rotation on a horizontal transverse axis and adapted to engage said wall, whereby movement of the lower end of said lever outwardly from said wall will force the lower end of said arm away from said wall to be supported relative to said wall only through said lever and said roller.

6. An overhead projection screen holder as recited in claim 4 wherein said arm is provided adjacent its lower end with a horizontally and transversely extending crossrod engageable in a notch formed in said lever and opening outwardly from said wall, whereby said lever is detachably pivoted to said arm.

8. An overhead projection screen holder as recited in claim 6 for use in connection with a pliable projection screen normally reeled in a case carried at the upper end of said arm and extendable downwardly from said case, and wherein said lever is provided at its lower end with a hook to which the lower edge of said screen is attachable when extended, said lever being reversible when detached from said arm for use with said hook uppermost as a tool to reach and extend said screen from said case.