Patent GB-941198-A (GB)
Title: An improved collapsible stand for a flexible projection screen
IPC: G03B21/58
Filed: 1961-05-15
Abstract: 941,198. Stands for projection screens. H. RIEDEL. May 15, 1961 [May 14, 1960], No. 17618/61. Heading G2J. A stand for a projection screen capable of being rolled up is characterized by the feature that it comprises a stand tube, which is mounted upon a detachable and collapsible foot, and upon which an upper holding ring and a lower holding ring are mounted, these rings each being equipped with a pair of rocking arms carrying a horizontal batten, the screen being kept taut when in use between these two battens, and at least one of the holding rings being slidably adjustable along the stand tube, and being capable of being held in its adjustable position. As shown (Fig. 1) a screen stand comprises a tube 1, upper rocker arms 6 and 7 pivotally mounted on a ring 2, lower rocker arms 25 and 26 pivotally mounted on a ring 24 and detachable feet members 27 which are releasably held by spring detent means (Fig. 3 - not shown) in slots (Fig. 4 - not shown) in a base 29. Lugs 43 of a drop ring 42 engage the feet members 27 to hold them in position. The screen 17 is attached at top and bottom to battens 34, 37 which are supported on the ends of the rocker arms by means of pins 47 engageable in holes in the battens and pivoted resilient shackles 49 (which may be detachable from the rocker arms). Lugs 35 and 36 on the ring 24 and lugs 8 and 9 and spring detent pins 10 and 11 (Fig. 5 not shown) on the ring 2 are provided to hold the rocker arms in the illustrated positions. To enable the tension in the screen 17 to be adjusted ring 2 is slidably adjusted along the tube 1 by means of a screwthreaded bolt 4 (Fig. 2) having a milled adjusting disc 3 and extending between the ring 2 and a fixed ring 5. The lower part of the stand is arranged in a telescopic manner with a tube 22 which may be clamped to tube 1 in any position by rotation of a ring 23. For convenience of transport, the arms 25, 26 may be folded into the position shown in dotted lines and similarly, after the spring detent pins 10, 11 have been depressed, the arms 6 and 7 may be folded into the positions 6<SP>1</SP>, 7<SP>1</SP>. Further, the feet members 27 may be detached and stowed as shown in Fig. 2 with their lower ends engaging in slots in the ring 24 and their upper ends held by a clamping ring 30. The screen-when rolled up-may be stowed inside the hollow tubes 1 and 22. In a modification (Fig. 7) the arms are held in the operative position by means of the bent over ends of a resilient shackle 50, pivoted at 51 to the ring 2. In a second embodiment (Fig. 8) the upper rocker arm mounting ring 55 is screw threadedly mounted on a tube member 57 which is rotatably mounted on the top of the stand tube 84. The ring 55 is prevented from rotating by means of a tongue 89 sliding in an axial slot therein and secured to a fixed ring 90 so that adjustment of the tension of the screen is now obtained by rotation of the member 51. Further, the upper rocker arms 68 (Fig. 12) which are pivotally mounted in slots 59 in the ring 55 are hollow and carry spring-urged rollers 69 which engage a cam surface 78 of the ring 55 and snap into a recess 63 when the rocker arms are raised to hold them in their operative positions. When both sets of rocker arms are folded down for transport, the upper arms 68 engage over the lower arms 95 (as shown in Fig. 1), a resilient locking band 99 being provided for holding the arms in position. The feet members 101 are stowed for transport as in Fig. 8. A modified shackle 106 for attaching a batten 108 to a rocker arm 104 is shown in Fig. 15. A modified foot arrangement is illustrated in Figs. 17 and 18 (not shown).