US1578514A - Photographic means for recording sound - Google Patents

Description

March 30 1926. 1,578,514

R. HART PHOTOGRAPHIC MEANS FOR RECORDING SOUND Filed May 18, 1925 UUUUUUU ll g. .17.

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Patented Mar. 30, 1926.

I z RUSSELL HART, OF LOS ANGELES, CALIFORNIA.

PHOTOGBAPHIG MEANS FOR RECORDING SOUND.

Application filed-May 1a, 1925. Serial No. 31,251.

To all whom it may concern:

Be it known that I, RUSSELL HART, a citi- E zen of the United States, residing at Los Angeles, in the county of Los Angeles and State of California, have invented a new and useful Photographic Means fonRecording Sound, of which a specification is set forth below. I

In this specification, and the accompanying drawing, I shall describe and show a pre ferred form of my invention, and specifical- 1y mention certain of its more important objects. I do not limit myself to the forms disclosed, since Various changes and adaptations may be made therein without departing from the essence of .my lnvention as hereinafter claimed; and objects and advantages, other than those specifically mentioned, are included within its scope.

My invention relates to photographic.

means for recording sound and its principal objects are; first, to provide means for pro- I jecting an exceedingly thin beam of actinic rays upon a movable photo-sensitized film; second, to afford facilities for vibrating the beam telephonically so as to produce a continuous sound record upon the film when the latter is given a uniform motion; and, third, to accomplisli the above by means of apparatus of great simplicity.

My objects are attained in the manner illustrated in the accompanying drawings, in which Figure 1 is a fragmentary plan view of one form of my invention, in which certain parts are shown in section;

Figure 2 is an elevation of the above construction,'shown partly in section and with a portion of the camera box removed;

Figure 3 is an elevation of a short section of film on which a sound record has been recorded in the manner to be described hereafter; and

Figure 4 is an elevation of a satisfactory type of light' source for use in connection with my invention.

Similar reference numerals refer to similar parts throughout the several views.

Myapparatus comprises a suitable base 5 adapted for mounting on a camera in any convenient manner as by a bracket and screw holes 6. Upon an extension of the base is mounted a relatively large sprocket drum 7 with sprockets 8 adapted for engaging a moving picture film There are also a pair bf rollers 10 for guiding the film. These parts are all withina light-proof camera box of which a portion of the wall is shown at 11. Outside of the camera. box is a magnet 12 which may be either a permanent magnet or an electro-magnet, as indicated in Fig. 2.

This magnet has opposed bifurcated poles,

the opposed faces of which are slightly spaced. In the form depicted one pair of the pole branches 13 and 14 are integral with the magnet frame. The other pair of pole.

branches 15 and 16 are adjustable by means of screws 17 so that the gap between their faces may be varied. Inthis manner it is ossible to compensate for the different engths of the magnetic circuits through the pole bifurcations, so that approximately the same magnetic flux may be made to pass between each pair of pole faces. That is to say,

the flux through the gap between poles 13 and 14: may be made to closely approximate the flux through the gap between pole faces 15 and 16. In certain cases it may be advisa ble to make the poles of both pairs of bifurcations adjustable.

A small cylindrical armature 18, intermediately. pivoted at 19, is mounted cen trally in such a manner that its extremities are in the respective magnetic fields of the bifurcated magnet poles. This armature carries a small cylindrical mirror 20 coaxially mounted upon its upper extremity. The purpose of this mirror will be explained presently.

Surrounding the armature in an energizinm coil 21 adapted by means of its termina wires 22 to be connected into a telephonic circuit.

It will be noted that the two pole bifurcations on each side of the armature are of the same polarity. That is, both pole bifurcations on the left are either north or south and on the right are either south or north. When coil 21 is energized one pole of the armature becomes north and the other south and therefore the magnetic attractions of the bifurcated poles cooperate in causing it to swing about its pivot. Changes and reversals of current in coil 21 obviously cause the armature to vibrate in consonance therewith at variable frequency and amplitude corresponding in the characteristics of the telephonic current.

The armature is prevented from contacting with the pole faces by means of resilient material 23 crowded in between the armature and one or both pairs of pole faces- This material also damps the armature movements in a manner that has been found in practice to be highly desirable for sound recording. I have found that sponge rubber is an excellent material to use for this in a bracket 25 and extending through wall 11 of the camera box. This tube is longitudinally slidable so that a secondary image of a primary image thrown upon the mirror, may be focused by means of lenses 26 upon the film in a direction normal to its surface. The set screw 27 maintains the focus when the adjustment is complete.

' For the light source I prefer to employ a lamp of the type shown at 28 having a th1n rectilinear filament 29 and mounted vertically in any convenient manner as by means of base 30. If a lamp of this character is po s1- tioned approximately as shown in 1, its rays 31 will fall upon cylindrical mirror 20 and be reflected in the form of a much attenuated primary image 1n the d1rect1on of lenses 26. The latter may be made to focus a sharp secondary image, which may be further attenuated, upon the film at 32. In this manner the actinic rays falling upon the film are made to take theform of an exceedingly thin beam of light which 1s v1- bratile in the direction of motion of the film. Vibratory movements of the arma ture and mirror therefore may be made to expose a longitudinal strip upon the moving film and if the movement of the film is uniform, and the vibrations are produced tele phonically, the film when developed will show a sound record of the character shown at 33 in Fig- 3.

The sound record comprises a series of variably spaced parallel lines of var1able density. The spaces between the lines are also slightly exposed and of variable density. 'For reproduction of the recorded sound the filmis made to pass at a uniform s eed, corresponding to the recording spec in front of a suitable photo-electric cell and a tenuous beam of light is caused to pass through the record and impinge upon the cell. There are various known means for reproduction in this manner and the reproduction is not a part of the present invention and not claimed herein.

The film is preferably driven at a uniform velocityby means of the sprocket drum 7 and the latter is relatively largeand fairly heavy so that its inertia may exert an appreciable effect in maintaining a uniform motion of the film during the recording. This arrangement is far better than running the film through an exposure gate for the reason that it completely eliminates chattering or vibration of the film by reason of its being pulled through such gate. Vibrations of this character of course produce stray noises and injure the quality of the sound record. Moreover the large sprocket drum 7 accurately positions the film during the recording process. 1

Having thus fully described my invention in a manner that will be clear to those familiar with the art concerned, I claim: v

v 1. Photographic sound recording means comprising; a uniformly moveable photo- 'sensitized film; a light source; and a cylindrical mirror, vibratile to sound, whereby an attenuated image of said source may be thrown upon said film transversely to its direction of motion.

2. Photographic sound recording means comprising; a uniformly movable photosensitized film; a rectilinear light source; a cylindrical mirror, vibratile to sound, adapted to reflect an attenuated image of said source; and a lens intermediate said mirror and said film, whereby an attenuated secondary image of the first said image may be projected upon said film transversely to its direction of motion.

3. Photographic sound recording means com rising; a uniformly movable photosensltized film; an illuminable rectilinear filament of great tenuity; a cylindrical mirror, vibratile to sound, adapted to reflect an attenuated image of said filament; and a lens intermediate said mirror and said film, whereby an attenuated secondary image of the first said image may be focused upon said film transversely to its direction of motion.

4. Photographic sound recording apparatus comprising; a uniformly movable photo-sensitized film; an illuminable recti linear filament; a cylindrical mirror, vibratile to sound in a plane parallel to the film, adapted to reflect an attenuated image of said filament; a lens intermediate said mirror and said film, whereby an attenuated secondary image of the first said image may be focused 'upon said film transversely to its direction of motion; and telephonic means for vibrating said mirror.

5. Photographic sound recording apparabe focused upon said film transversely to its direction of motion; and means for energizing saidcoil by a telephonic current.

6. Photographic sound recording apparatus comprising; a uniformly movable photo-sensitized film; an illuminable rectilinear filament; an intermediately pivoted armature having its extremities in constant magnetic fields of the same flux direction, and adapted to vibrate in a plane parallel to the film; a coil surrounding said armature adapted for variably magnetizing it; a cylindrical mirror mounted upon an extremity of the armature co-axial therewith,

' and adapted to reflect an attentuated image of said filament; a lens intermediate said mirror and said film, whereby an attenuated secondary image of the first-said image may be focused upon said film transversely to its direction of motion; and means for energizing said coil by a telephonic current.

7 Photographic sound recording apparatus comprising; a uniformly' movable photo-sensitized film; an illuminable rectilinear filament; means for producing a pair of contant magnetic fields, parallel to each other and of the same flux direction; .an intermediately pivoted armature having its respective extremities in said fields, and adapted to vibrate in a plane parallel to the film; a coil surrounding said armature adapted for variably magnetizing it; a cylindrical mirror mounted upon an extremity of the armature co-axial therewith, and adapted to reflect an attenuated image of said filament; a lens intermediate said mirror and said film, whereby an attentuated secondary image of the first said image may be focused upon said. film transversely to its direction of motion; and means for energizing said coil by a telephonic current.

8. Photographic sound recording apparatus comprising; a uniformly movable photo-sensitized film;van illuminable rectilinear filament; a magnet having opposed bifurcated poles with gaps between the respective. opposed pole faces; an interme-h .and means for energizing said diately pivoted armature having its respective extremities in said gaps, and adapted to vibrate in a plane parallel to the film; a coil surroundingsaid armature adapted for variably magnetizing it; a cylindrical mirror mounted upon an extremity of the armature co-axial therewith, adapted to reflect an attentuated image .of said filament; a lens intermediate said mirror and said film, whereby an attentuated secondary image of the first said image may be focused upon said film transversely to its direction of motion;

coil by a telephonic current.

9. The construction set forth in claim 8 in combination with means for varying the width of the gap between opposed pairs of the magnetic pole faces.

10. The construction set forth in claim 8 in combination with; means for varying the width of the gap between opposed pair of the magnetic pole faces; and resilient packing between the armature and pole faces whereby the armature is prevented from contacting with the polefaces and its vibratory movements are damped.

11. Photographic sound recording apparatus comprising; a rotatable sprocket drum; a uniformly movable photo-sensitized film bent around said drum and engaging said sprockets; a light source; and a cylindrical mirror, vibratile to sound, whereby an attenuated image of saidsource may be thrown upon the portion ofthe film engaging the drum, transversely to its direction of mot-1on..

12. Photographic sound recording appa .source; and a cylindrical mirror, vibratile to sound, whereby an attenuated image of said source may be thrown normally upon the. portion of the film engaging the drum, transversely to its direction of motion.

' RUSSELL HART.

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