US2476521A

US2476521A - Screen for picture projections

Info

Publication number: US2476521A
Application number: US775403A
Authority: US
Inventors: Waller Fred
Original assignee: VITARAMA CORP
Current assignee: VITARAMA CORP
Priority date: 1947-09-22
Filing date: 1947-09-22
Publication date: 1949-07-19
Anticipated expiration: 1966-07-19

Description

F. WALLER SCREEN FOR PICTURE PROJECTIONS July 19, 1949.

2 Sheets-Sheet 1 Filed Sept. 22, 1947 lNVENTOR Jul 19, 1949. WALLER 2,476,521

SCREEN FOR PICTURE PROJECTIONS Filed Sept. 22, 1947 2 Sheets-Sheet 2 INVENTOR 4% i? VZATTORNEY Patented July 19, 1949 UNITED STATES PATENT OFFICE 2,476,521 SCREEN FOR PICTURE PROJECTIONS Fred Waller, Huntington, NL- Y., assignor to The Vitarama Corporation, Huntington Station; N.- Y., a: corporation of New York Application September 22, 1947, Serial No. name Claims.

This invention relates to screens for picture projection. More particularly the invention relates to curved screens in which there is a tendency of light projected against one area of the screen to be diffused, scattered or reflected in such manner as to impinge upon other areas of the screen thereby degrading and reducing the contrast of the images in such other areas.

It is an object of the invention to provide a curved screen in which the degrading effect of such diffused, scattered oi' reflected light is minimized.

It is a further object of the invention to provide a construction which may be built at relatively low cost and which may be easily assembled and disassembled when required.

Other objects and advantages of the invention will appear hereinafter.

A preferred embodiment of the invention selected for purposes of illustration is shown in the accompanying drawings, in which,

Figure 1 is a top plan view of the screen, showing a foundation member with a few of the screen elements mounted thereon.

Figure 2 is an enlarged detail view showing the manner of mounting the screen elements on the foundation members. v

Figure 3 is a plan view on a portion of a screen element illustrating the crimping of the same.

Figure 4 is a section on the line 4-4 of Figure 3.

The principles involved in the invention hereinafter described may be applied to a wide variety or single curved surfaces, i. e. surfaces generated by moving a straight line along a curved path such as a circle, a parabola, a hyperbola or an ellipse while held at right angles thereto, to generate a cylindrical surface, a parabolic surface, a hyperbolic surface or an elliptical surface. Furthermore, I include within the term single curved surfaces those generated by moving a straight line along and at right angles to a curved path which may include straight sections, to generate a surface in which the overall effect is that of a single curved surface. In the embodiment shown, I have illustrated the invention as embodied in a cylindrical screen as typical of the single curved surfaces to which it is applicable.

Thus, referring to the drawings, the screen comprises upper and lower foundation members I and 2, preferably channel shaped as shown, which said members may be supported and spaced by any suitable arrangement of structural supporting members (not shown). The foundation members are curved circularly, as shown in Figure 1, to support the cyIindrical projection surface and extend through any desired are. They are supported in parallel relationship spaced to provide whatever vertical screen expanse is desired. In applying the" invention to other single curved surfaces, the curvature of the foundation members would be altered to conform to the curve selected.

The projection surface, i. e. the surface against which the projected image impinges, is made up of a series of screenelements 3 consisting of spaced strips extending from one of the foundation members to the other. The said strips are anchored to the upper and lower foundation members by suitable brackets 4' and 5, which said brackets may be secured to the foundation members by suitable bolts.

It is desirable that the screen elements be easily and quickly attachable to or removable from the foundation meriibers soas to permit the screen to be quickly assembled and disassembled. It is also desirable that the screen elements be maintained under tension while attached to the foundation members. For these purposes the upper brackets 4 are provided with studs 6 adapted to receive theslots I in the upper ends of the strips and the lower brackets and the lower ends of the strips are provided with

apertures

8 and 9, respectively, to receive the ends of the springs I U which subject the strips to tension.

Preferably the strips are additionally maintained in alignment at one or more points between the upper and lower foundation members, as by means of an angle bracket II having slots I2 formed therein to receive the edge of the strip and hold its against twisting. The slots, of course, are cut to lie parallel to the front faces of the

brackets

4 and 5, so that the front surface of each strip is a plane surface. The brackets Il may be secured to the supporting structure in any desired manner.

The screen elements are preferably formed from relatively thin sheet metal, and it has been found that in the process of cutting the strips from a sheet, it is virtually impossible to avoid a certain amount of distortion of the strips, with the result that even with the use of the brackets I I and tensioning springs I0 there is a tendency for portions of the strips to twist out of the desired plane. I have discovered that this may be easily corrected by crimping the strip wherever this tendency is observed. Thus, as illustrated in Figures 3 and 4, I introduce a V-shaped crimp l3 extending transversely across the strip, the depth of the crimp being greatest at one edge of the strip and tapering oif toward the other edge. This has the efiect of shortening one edge of the strip, and by applying such crimps wherever distortion occurs, and by adjusting the depth of the crimp in accordance with the degree of distortion observed, the strip may be quickly straightened. One or two crimps are usually sufficient to correct the distortion.

The

brackets

4 and 5 are spaced along the foundation members in such manner that when the screen is viewed from the point at which the pictures are projected, which point preferably coincides with or lies behind the center of curvature of the screen, one vertical edge of each screen element overlaps the opposite edge of the next adjacent element, so that the projected image falls entirely on the surfaces of the screen elements.

Furthermore the

brackets

4 and 5 are so adjusted on the foundation members that the planes of the screen elements all intersect at the center of the screen surface as indicated by the construction lines X of Figure 1. With this arrangement the principle reflection from each screen element is in the direction of the audience and away from all of the other screen elements, so that the reflected light as well as diffused or scattered light emanating therefrom are least likely to be directed toward any other screen element. Moreover, with this arrangement, such diffused or scattered light as may be directed toward any other portion of the screen is least likely to find a screen element surface on which it may impinge.

It will be understood that the invention may be variously modified and embodied within the scope of the subjoined claims.

I claim as my invention:

1. A picture projection screen comprising spaced, curved foundation members and a series of screen elements extending between said foundation members, said screen elements comprising strips having substantially plane surfaces arranged in overlapping relationship and together constituting a single curved projection surface, each of said strips being anchored to said foundation members by means including a spring which subjects the strip to tension.

2. A picture projection screen comprising spaced, curved foundation members and a series of screen elements extending between said foundation members, said screen elements comprising strips having substantially plane surfaces arranged in overlapping relationship and together constituting a single curved projection surface,

and a bracket member having slots engaging the edges of said strips at points between said foundation members and holding said strips to prevent twisting of said strips.

3. A picture projection screen comprising spaced, curved foundation members and a series of screen elements extending between said foundation members, said screen elements comprising sheet metal strips, said strips being straightened by transverse V-shaped crlmps so that when extended between said foundation members their surfaces are substantially plane surfaces, said surfaces being arranged in overlapping relationship and together constituting a single curved projection surface.

. 4. A picture projection screen comprising spaced, curved foundation members and a series of screen elements extending between said foundation members, said screen elements comprising sheet metal strips, said strips being straightened by transverse V-shaped crimps so that when extended between said foundation members their surfaces are substantially plane surfaces, said surfaces being arranged in overlapping relationship and together constituting a projection surface, each of said strips being anchored to said foundation members by means including a spring which subjects the strip to tension.

5. A picture projection screen comprising spaced, curved foundation members and a series of screen elements extending between said foundation members, said screen elements comprising sheet metal strips, said strips 'being straightened by transverse V-shaped crimps so that when extended between said foundation members their surfaces are substantially plane surfaces, said surfaces being arranged in overlapping relationship and together constituting a projection surface, the planes of said surfaces intersecting at the center of said projection surface.

FRED WALLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,273,074 Waller Feb. 17, 1942 FOREIGN PATENTS Number Country Date 479,913 Great Britain Feb. 14, 1938