US2290287A - Motion picture projection apparatus - Google Patents

Description

J. A. LINKS zr'm... xombu PICTURE rnoJsc'rltm APPARATUS July 21, 1942;

Filed Sept. 5, 1939 2 Sheets-Sheet l INVENTORS JUL/4N A. LIN/(.5

JIEOM! P. H5257 BY 1 a 6g 2 ATTORNEYS July 21, 1942. J. A. LINKS ETA L 2,290,287

MOTION PICTURE PROJECTION APPARATUS Filed Sept. 5, 1959 2 Sheets-Sheet 2 INVENTORS JUL/AN 8.1 INKS JEEOIVE P. HEBST flyqfl ATTORNEYS Patented July 21, 1942 UNITED STATES PATENT OFFICE MOTION PICTURE-PROJECTION APPARATUS Julian A. links and Jerome P. Beret, San Francisoo, CaliL, assignors of one-half to Max Jay Hirsch, San mm, Calif. Application September 5, 19:9, No. 293,34:

(:. as-a'i) 6Ciaims.

This invention relates to a moving picture projection apparatus andhas for one of its objects a more compactly arranged moving picture projector and reels therefor than heretofore. Another object of the invention is a complete prolector, reels and screen all arranged compactly in a portable cabinet with the reels disposed adjacent two of the sides of the projector in positions at a lower elevation than heretofore, and I in which they are more nearly within the prolected area of the said sides than in the conventional projectors. Still further objects of the invention are improved means for projecting a larger image on a screen positioned relatively close to the projector, without noticeable distortion, and an improved screen for such image. Other objects and advantages will appear in the specification and drawings.

In the drawings, Fig. 1 is a perspective view of the cabinet containing all the essentials for projection of a relatively large image from either eight or sixteen millimeter film.

Fig. 2 is a horizontal sectional view of the apparatus of Fig. 1 taken just below the top of the cabinet and through the screen and mirror.

Fig. 3 is a horizontal, fragmentary sectional view of a portion of the lower part of the cabinet showing the take-up reel therein in dotted line, and the means for guiding the film thereto and also the means for regulating the speed of the take-up reel.

Fig. 4 is a sectional view of one film guide as seen along line 4-4 of Fig. 3.

Fig. 5 is an enlarged sectional view through the reel mounting shaft for the take-up reel as seen along the line 5-5 of Fig. 3.

Fig. 6 is a sectional view through the improved projection lens of the projector.

In detail, the apparatus as illustrated in the drawings comprises a generally oblong cabinet having a front side I, rear side 2, ends I, 4, and a bottom, section I, which bottom section is relatively shallow, vertically, and carriua bottom I (Fig. 3) with short vertically extending sides and ends in substantially downward continuation of the sides and ends of the main body of the cabinet. The said bottom section is hinged to the lower edge of the rear side 2, as at I (Fig. 1),'for tilting the body of the cabinet at its forward side, upwards, away frmn the lowersection. The main body section carries a bottom portion 8 (Fig. 2) wholly or partially covering the lower section. The bottom section and the main body portion of the cabinet arereleasably secured together by hooks Q at opposite ends of the cabinet, as indicated in Fig. thus permittingthe entire cabinet to be lifted and moved about 'as a unit without danger of the bottom swinging Open.

0n the bottom 1 of themain body section. is a conventional, vertically disposed projector it, the one indicated generally inthe drawing being a projector for home motion pictures, such as for 8 mm. or 18 mm. film. The film drive is conventional, hence is not shown indetail, it being sufilcient to state that the drive pulley indicated at Ii is connected, by conventional drive connections with the motor, for driving the film from the feed reel past the projection lens, indicated at I2.

Heretofore'the feed reel and take-up reel have been mounted one above the other at the forward end of the projector, and since these reels are from five to ten inches in diameter, and larger, considerable space is required to accommodate the reels in this position. Also, in the projectors for 8 mm. film, only relatively small reels can be used, hence only short pictures can be shown, and the reels must be frequently changed. The arrangement of the feed and take-up reels in this invention enables long reels orshortreelstobeusedwith theminimum of space required for the same.

Reierring to Fig. 2, the feed reel is indicated at it, rotatably mounted for rotation on a horisontalshaltllsupportedontherearside 2 oi the cabinet. The position of this reel is sub stantlally alongside one side of the projector it, so that the bottom of the reel is substantially opposite the base of the projector II when a reel, say of about 15 inches in diameter, is on the shaft.

From said reel it the film II is led around a guide pulley ll supported forwardly of the projector from a bracket II that is carried on said projector. The film passes over the conventional drive pulley ll, then between the lens I! and the light aperture ll and below. drive pulley H to a guide pulley 2| over which pulley the film passed downwardly to engagement with another guide pulley 2|.- From said guide.pulley ii the film passesthroughanopening ninth'ebottom 8.

A roller 23. guide channel strip 24, and roller 2| are secured to partition 21 in the bottom I of the cabinet guide film ll to reel 1!, the rollers 23, II being at the ends of the strip and the strip being given a half turn (Pig. 3) 00 change h direction of the film. lThe'sides "of the channel strip have inturned flanges to. retain the film in the channel and the base of the channel is recessed to prevent contact between the emulsion on the film and strip in the event the emulsion is facing the strip (Fig.4) Brackets 26 support the strip on the partition with the roller 21ladjacent opening 22 and roller 2! adjacent the periphery of conventional take-up reel 2! (in dotted line Figs. 2, 3). This take-up reel 29 is horizontally disposed, and carries a tapered central bearing 2! (Fig.6) adapted to frictionally fit over the tapered upper end 80 of a vertical shaft 2i. Secured at the lower end of said end 32 is a horizontal disk 32 adapted to support the reel 29 against any tendency to wobble.

The shaft 2| is driven by a motor 32 through gearing 24 and the speed of shaft 8| is controlled by a centrifugal governor fl that is in driving connection with the drive shaft II through gearing 2'. Disk 21, connected with the axially movable hub of the governor, is adapted to be engaged by a felt or leather brake 28 supported on one arm SI of a modified ball crank, the other arm ll of which crank is held by a spring ll against a cam 42 secured on a shaft. that rotatably extends through the forward wall of the bottom section I. A knob 44 is secured to the end of shaft 42 that projects outwardly of said section 8, which knob carries a pointer 45 adapted to scan indicia, indicated at 48 in Fig. l, for indicating the desired control for the speed of the take-up reel 28. Upon rotating the knob 44 in one direction, the low side of cam 42 will engage arm ll, thus decreasing the resistance on motor I2, and increasing the speed of reel 29 for driving say 34 frames per second, or by turning the cam so its high side engages arm. 40 the speed may be reduced for driving, say 15 frames per second. By turning the cam to positions where the arm 4| is engaged between the high and low sides, other speedsbetween the fastest and slowest speeds may be procured. In fact any desired speed between high and low can be accurately and positively obtained.

In order to compensate for the difference in the speed of the film on the takeup reel at the hub and adjacent the periphery, the said hub is nicely fitted on the end 2| of shaft Ii to permit slippage between the hub and end 2| when the tendency of the reel is to draw the film from the drive pulley Ii on the projection at a rate of speed faster than that at which said pulley draws the film from the feed reel. The desired speed of driving the reel 2| at the circumference of the film supportingportion 41 of reel 28 (Fig. 5) is substantially equal to the speed at which the pulley, ii feeds the film past the projector. Thereafter, as the film winds on reel 2! to a sufiicient degree, which is only noticeable in the larger diameter reels, the slippage between portion 3| and hub 2! will In order to remove and to replace a reel in the bottom section I, it is only necessary to tilt the main body upwardly, and conventional pivotally stop links 40 (indicated in dotted line in Fig. 1), that connect between the body of the cabinet and the bottom, will support the main body against accidental tilting at too great a degree, and such links will likewise support the cabinet in tilted position against failing, until the links are collapsed in the usual manner.

Forwardly of the lens l2 and across the corner of the cabinet at the juncture of end 4 and rear side 2, we posi ion a fiat mirror 52, which mirror is disposed in a vertical plane at a subtsantially 45' angle to the central axis of the lens. In the forward side I of the cabinet is an opening 5|,

and just inside said opening is a fiat, translucent, or frosted screen 82, which screen may be of glass or Celluloid, or the like. This screen 52 is planar sided, but is curved in the direction of its horizontal width, the degree of said curvature being substantially that of the curvature of the field projected by lens i2, indicated in Fig. 2 at X. The area of screen is of course larger than the area of the mirror 52, and is approximately 10 x 12 inches, which is substantially th actual size of the image projected from an 8 mm. film positioned a total of only about 24 inches from the projection lens I2 to said screen by way of the mirror. The size of the main body of the cabinet itself is only about 15" x 24" x 15''. Thus it will be seen that a greatly enlarged image is produced on the screen 62 (which image is viewed from the front of the cabinet), although the actual distance of the film from the projector is appreciably less than is usual for even a smaller image.

The opening it is adapted to be closed by swinging doors 5: hinged at 84 to opposite lateral edges of the opening.

One of the features that enables the large image onscreen 82 within the short distance of the latter from the projector, is the lens assembly 12. This assembly comprises a pair of piano-convex lens 55 each with a bi-convex lens 58 cemented in the usual manner in the concave side of one of the piano-convex lens. The piano-sides of the piano-convex lens face outwardly in the barrel 5'! with one of the convex sides of the bi-convex lens facing toward each other. This type of lens is generally known as a wide angle lens, and provides for an appreciably enlarged image, with inappreciable distortion, which is less as the distance between the lens and the screen is increased. The short distance between the screen and lens, in our cabinet, makes it desirable, however, to curve the screen, as already described.

In order to provide access to the projector and feed reel, in the cabinet, the top of the cabinet is cut away and a hinged lid 58 is provided (Fig. 1), which lid may be swung on hinges S9 to over the remainder of the top 2. Thus all the working parts of the projector, as well as the reel H are accessible to an operator.

The bottom section I also provides ample space at the side of the partition 21 opposite reel 29 for storing extra reels, indicated in dotted line at 80, in Fig. 2.

Where small 8 mm. film is used, the take-up reelis, of course, relatively small as compared with the reels I 3, 28, in which case, the body portion of the cabinet is complete in itself for the take-up reel, in which case, said reel, indicated'at ii is mounted alongside the projector Ill, opposite the side facing the reel l2. The film i 5, upon leaving pulley 2| in this latter instance, is conducted over pulley 62, that is secured to the lower portion of end 2, and from pulley 62 said film is carried upwardly and over pulley 62 secured to the same side 2 near the top and adjacent front wall I. From pulley 62 the film (indicated in dotted line at I 5') is passed over reel SI for winding on the latter. The reel I is driven by a motor N, the said reel being a friction fit on shaft Iii, but capable of slipping relative to said shaft in the event of excess tension on the film.

It is accordingly seen from the foregoing that provision is made in our device for extra large reels as-wellas for the smaller reels, and yet the entire projection equipment, including the screen, is contained within a small cabinet. Also, our arrangement enables the projection on said screen ofa much larger image than heretofore considering the size of the film.

The power for the light-and motors may be supplied through the usual plug ,to the apparatus controlled by suitable switches 61 and a rheostat 68 on the end :8 or in any other desired location, but preferably accessible outside the cabinet.

Having described our invention, we claim:

1. Apparatus of the character described, com prising an elongated, oblong cabinet with vertical lateral sides having therein a substantially vertical, flat, reflector and a substantially vertical, rectangular screen of light transmitting material respectively disposed at opposite sides of said cabinet at one end thereof; a motion picture projector within said cabinet at the opposite end having a projection lens arranged to project rays of light forming a picture generally horizontally directly onto said reflector for reflection from the latter generally horizontally directly onto said screen, said screen and said reflector and said projector being positioned at generally the same horizontal level whereby said screen and said reflector are horizontally oilset relative to said projector to positions entirely removed from heat rising from said projector; a rectangular opening formed in the side wall of said cabinet opposite said reflector substantially the width of said latter wall in direction of its shorter dimension and said screen being substantially the same size as said opening and being secured in the latter; a horizontal reel for receiving motion picture film from said projector after movement of such film past said lens; said reel being positioned below said projector and within the confines of said cabinet.

2. A device of the character described, comprising, a cabinet having lateral side walls, a

motion picture projector in said cabinet havinga projection lens arranged to project rays of light generally laterally across the interior of said cabinet and formed to project said rays substantially divergently therefrom, one of said lateral side walls being formed with an opening therein, and a generally rectangular, substantially vertical screen positioned in said opening, a flat light reflector positioned within said cabinet to receive said rays directly from said lens and to directly reflect said rays onto the side of said screen facing into said cabinet, said screen bein a sheet light transmitting material curved horizontally with the said side thereof facing into said cabinet being the concave side of said screen and the curvature of said screen correspondingto the curvature of the field of said lens whereby the horizontal distortion of the picture resulting from the divergence of said rays, and observable only on the opposite convex side of said screen outside said cabinet by an observer outside said cabinet will be materially rectified, the relation between said lens, reflector and screen and the refractive characteristics and form of lens being such that the horizontal dimension of the image received on said screen is equal to substantially one-half of the total length of travel of the rays from said lens to said screen.

3. A device of the character described, comprising, a cabinet having lateral side walls, a motion picture projector adjacent one of said lateral sides and having a projection lens arranged 'to project rays of light generally horizontally across the interior of said cabinet, said lens being a wide-angle lens whereby the opposite outside rays, relative to the central axis of said lens, are projected from said lens at a relatively wide angle, one of said lateral side walls being formed with an opening therein, and a substantially rectangular, substantially vertical screen positioned in said opening, a light re, fiector positioned within said cabinet adjacent the side wall opposite the said one of said lateral sides to reflect said rays transversely across the interior of said cabinet and onto the side of said screen facing into said cabinet, said screen being a sheet of light transmitting sheet material curved horizontally with its concave side being said side facing into said cabinet, the degree of said curvature of said screen being such that the rays of light in a medial plane horizontally dividing the field of rays projected from said lens and reflected by said reflector will be of substantially equal length from said lens to said screen thereby rectifying the distortion of the picture on said screen when the latter is observed from outside said cabinet in viewing the convex side of said screen, and also materially equalizing the brilliancy of said picture at all points thereof.

4. In motion picture apparatus of the character described including a cabinet enclosing a motion picture projector having a projecting lens, a strip of motion picture film movable pasteach lens, a screen positioned to receive rays of light projected by said lens, a reel positioned to receive the said film in the form of a coil upon movement of said fllm through the projector and past said lens, and means for so moving said film and for revolving said reel; a film guide extending from said reel for guiding" film thereto, said guide comprising a channel strip slidably supporting said strip of film between the sides of said channel for longitudinal movement longitudinally of said channel, the bottom of said channel :being longitudinally recessed a width to clear the portion of said strip of film between the opposite longitudinally extending margins thereof while slidably supporting said margins at opposite sides of the recess in said bottom, whereby the portion of the film carrying the image to be projected by said lens will be free from engagement with said channel strip during sliding movement along said strip, and the sides of said channel strip having flanges secured thereto, said flanges extending toward each other and over only the opposite longitudinally extending margins of said strip of film.

5. In a construction as defined in claim 2, said reel being positioned horizontally below said projector and lens, and rollers rotatably supported on opposite ends of said channel strip for supporting said fllrn upon its entering and leaving the latter, said channel strip being curved longitudinally with one of its end portions extending upwardly toward said lens and with its opposite end portion substantially horizontal and planar with said reel whereby the said strip of film carried thereby will be curved corresponding with the curve of said channel strip during its longitudinal movement along said strip, and means supporting said channel strip stationary relative to said projector and said reel.

6. A device of the character described comprising, a cabinet enclosing a motion picture projector having a wide-angle projection lens with respect to ordinary motion picture projection lens and one reflector, a horizontally curved screen oi light transmitting sheet material securedinanopeninginoneoithelateralwalls of said cabinet positioned with its concave side facing into said cabinet and its convex side racinz outwardly: said reflector being the only reflector in said cabinet, and said projection lens, reflector and screen being podtioned relative to each other for projection of the image from said projector directly onto said reflector and for reflection oi the said image directly from said reflector onto said screen with the said image so projected and reflected substantially cover- 5 ing said screen.

JULIANLLINKB. JEROME P. HERST.

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