US2014537A - Sound reproducing device - Google Patents

Description

Sept. 17, 1935. M. H. PAGE 2,014,537

SOUND REPRODUCING DEVICE Filed Oct. 22, 1934 I N VEN TOR.

j ATTORNEY.

Patented Sept. 17, 1935 PATENT OFFICE 2,014,537 SOUND REPRODUCING DEVICE Milton H. Page, Chicago, 111., assignor to Trutone Audifilm Corporation, Chicago, 111., a corporation of Illinois V Application October 22, 1934,Serial No. 749,405

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My present invention relates to improvements in sound reproducing devices and constitutes changes in and refinements of the mechanism forming the subject-matter of United States Letters Patent No. 1,880,980, issued to me October 1, 1932.

A photo-electric cell is a device, the electrical conductivity of which changes with the change of the intensity of light to which it is subjected.

This characteristic of a photo-electric cell has been utilized in making sound records and reproducing sound from such records by modifying the intensity of a beam of light with means moved, or the movement of which is controlled, by the sound which it is desired to record and to reproduce.

In the patent heretofore referred to I have illustrated a fixed drum or cylinder, open at one end, on which drum, or about which drum, ro-

tates a pair of spaced cylinders upon which moving elements the film is carried over the space between the elements and in front of an aperture through the fixed cylinder. Light is transmitted to and through the aperture while the film is passing for the purpose of making the record and for reproducing the sound.

Roughly speaking, the range of vibration for audible sound varies from sixty to ten thousand per second so that it will be seen that the record should be made and reproduction accomplished within the highest degree of precision.

There are two features in the mechanism described in the aforementioned patent which tend somewhat to impair the precision of both the recording and the reproduction. First, the moving cylinders, no matter how precise their bearings are made, nevertheless retain some degree of play which is liable to, and does, amplify and also lessen the amplitude of some of the recorded vibrations. The second place where the mechanism described in the aforementioned patent may injuriously effect both the recording and the reproducing is that it carries the film across the recording and reproducing aperture in an are which disposes different portions of the film at different distances from both the source of illumination and the light sensitive element or photo-electric cell. The intensity of 50 light varies with the square of the distance of transmission so that it will be seen that this arc in which the film is disposed introduces possibilities of distortion both in recording and reproduction. A critical observer will note some 55 degree of roughness in reproduced sound, especially articulate sound, which is attributable in part at least to the causes above mentioned.

The object of my present invention is to eliminate the above distorting elements both with regard to the vibration of the film and the dis- 5 posal thereof in an arc at the time of recording and reproduction.

I have attained the foregoing objects by means of the mechanism illustrated in the accompanying drawing, in which- 10 Fig. l is a diagrammatic side elevation of the film handling and moving mechanism during recording and reproduction.

Fig. 2 is a front elevation, partially in section, of the drum and moving elements carried there- 15 by and the table for supporting the film during recording and reproduction.

Fig. 3 is a view similar to Fig. 2 of a modified form of construction; and

Fig. 4 is a fragmental section of another form 20 of assembly of drum and moving film carrier H elements.

Similar reference characters refer to similar parts throughout the respective views.

The mechanism employed for supporting film 5 during recording and reproduction consists of a drum 5, one end whereof is open and the other end 6 whereof is closed. To the closed end B, preferably centrally thereof, is fixedly secured a rod '5 which, in its turn, is secured to some convenient 30 secure support. Mounted to freely rotate about the drum 5 are a pair of spaced rings or annuli 8 and 9. In the forms-of construction shown in Figs. 2 and t the interior faces of the rings or annuli 8 and 9 are provided with ball races I El 35 and l l. One of the annuli is provided with a film guiding flange 12,

In the form of construction shown in Fig. 2 ball races are provided in the fixed cylinder 5 by reducing and threading the ends of the cylin- 0 der 5 and providing interiorly threaded rings I3 and i l. The inner edges of the rings 13 and M are cupped to provide segments of the ball races while the adjacent edges of the cylinder 5 are also likewise cut so that by an adjustment of 45 the rings l3 and it the ball bearings may be adjusted to carry the members 8 and 9 with a high degree of nicety.

In the construction shown in Fig. 4 I have entirely threaded the outer surface of the fixed cylinder 5 and formed the ball races by means of two pairs of rings i5 and i6 and ii and I8, the adjacent edges of which pairs of rings are provided with segments of ball tracks. This structure not only permits of the adjustment of the bearings with respect to the members 8 and 9, but also permits the relative spacing of the members 8 and 9. In the space between the members 8 and 9 a lateral aperture I9 is provided in the cylinder 5 through which light passes from a light source (not shown) in a casing 20 to the interior of the fixed cylinder 5 to a point 2| where the light responsive element, such as a photo-electric cell, may be mounted. The film 22 passes from a roll thereof (not shown) over a guide roller 23, over the rings 8 and 9 past the opening l9, and is led from the rings 8 and 9 to a guide roller 24 from whence it passes to a sprocket roller 25 driven by a suitable mechanism. A pressure roller 26 is employed to maintain proper relation between the film and the sprocket roller 25.

In the slightly modified construction shown in Fig. 3 the ring 8 is modified to a cylinder 8a with an end wall 812, the center whereof is suitably journaled as at on the rod 1. In this form of construction shown in Fig. 3 the outer supporting member 9a is fixedly secured to the cylinder 5 by a lock washer 9b. The structure as thus far illustrated and described was fully illustrated and described in the before mentioned patent.

In order to fiaten out the portion of the film which travels by the opening l9 and to deaden or kill any movement, except that of longitudinal progression, therein I have fixed to the fixed cylinder 5 a block or table 21 which is perforated and located so that the perforation therein registers with the aperture IS. The block 2! has its outer surface disposed in a single plane slightly further from the center of the cylinder 5 than a tangent thereto at the axis of said opening l9. The edges of the block may be beveled, as at 21a, to permit the film to more readily mount upon and leave the block 21. The block 21 is mounted upon the fixed cylinder 5 by means of a machine screw 28 passing through a perforated extension 29 carried by the block 21, which screw co-operates with a bored and tapped orifice provided in the fixed cylinder 5.

As the film is pulled by the rotation of the sprocket roller 25 around the fixed drum 5 upon the rotatable members 8 and 9 which move with the film, it passes out of the path determined by the members 8 and 9 up over the block 21 and is carried by the opening I 9 in a plane. The contact of the film with the block 27 deadens and. kills all motion except a longitudinal progression of the film as it passes the opening I 9.

light aperture and a block perforated to register with said aperture fixedly secured to said cylinder and extended to provide a plane surface parallel with and beyond a tangent to the film track determined by the movable film supporting means.

2. Mechanism for handling film during the recording of sound thereon comprising a cylindrical stationary member, means co-operating with said cylindrical member and moving with the film for supporting said film in its movement about a portion of said cylinder and a block fixedly secured to said cylinder and extended to provide a plane surface parallel with and beyond a tangent to the film track determined by the movable film supporting means.

3. Mechanism for handling film during the reproduction of sound from a record upon said film comprising a cylindrical stationary member having an aperture therein for the passage of light, means co-operating with said cylinder and moving with said film for supporting said film in its movement about a portion of said cylinder and in front of said aperture and a block perforated to register with said aperture fixedly secured to said cylinder and extended to provide a. plane surface parallel with and beyond a tangent to the film track determined by the movable film supporting means.

4. Mechanism for handling film during the recording and reproduction of sound comprising a cylindrical stationary member having an aperture therein for the passage of light, means for supporting said film in its movement about a portion of said cylinder consisting of a pair of annuli mounted in spaced relation with each other for free rotation about said cylinder and a block perforated to register with the aperture in said fixed cylinder and fixedly secured thereto and extended to provide a plane surface between 5 said annuli parallel with and beyond a tangent to the film track determined by said annuli.

MILTON H. PAGE.

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