US1810527A - Sound shutter - Google Patents

Description

June 16, 1931. F. H. OWENS 1,810,527

sUND SHUTTER FiledFeb. 3. 1927 2 Sheets-Sheet l a5 o cui /7 o s c:

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2 Sheets-Sheet 2 F. H. OWENS souND sHuTTER Filed Feb. 3,

lJune 16, 1931.

INVENTOR FREEMAN H. OWENS.

Patented June. 16, 1931 UNITED STATES PATENT OFFICE SOUND SHUTTEB Application "led February 3, 1927. Serial No. 135,682.

My invention relates to the recording and reproduction of sound photographically and comprises means for closing the slit through which the light passes in such recording or reproducing processes, either automatically or through the control of the operator.

It will be understood that in the reproduction of a sound record which has been photographed on film, the film is moved at a constant speed past a narrow slit over which the vsound record passes. A light of constant intensit is placed so that its rays pass through this s it and through the sound record as it moves past the slit. As this sound record varies in density at the point of passing the slit, rthe light rays from the lamp-passing through the sound record likewisewary in intensity, exactly as the soundrecord varies. This varying light acts upon a photo electric cell which sets up electric impulses in ac- .cordance with such light variations, which impulses after amplification in any Well known manner are passed to a loud speaker or other sound reproducing instrument where the sounds photographed on the film are rendered distinct and audible.

Naturally the amplification required to render the electric impulses given off by the photo electric cell strong enough to operate the loud speaker is very great. Consequently, all electric impulses set up by the photo electric cell, whether due to the light variations caused by the sound record or to the imperfections in the film, are greatly amplified andare audible through the loud speaker. l In fact, the film itself varies in color and light transmitting properties to such an extent that when no sound record is passing l the slit, a loud hissing or frying noise is audible through the loud speaker. O course, when a sound record is passing the slit, the sound itself reproduced in the loud speaker being of much greater volume overcomes thehissing noise produced by the film itself and the latter is therefore not noticeable. There are times, however, when there is an interruption of the sound record for one purpose or another and during these interruptions the hissing noise through the loud speaker is decidedly noticeable obiectionable.

In addition to this, there are of a necessity a number of splices in the sound film and at the points of splicing there is always a transparent line caused from scraping the film, as

well asconsiderable variation in the density of the film itself, which, as it asses the slit, causes a marked variation in t e light which reaches the photo electric cell, and in the case of the transparent line, which allows a flash of light to pass through to the photo electric cell, creates a loud booming noise in the loud speaker caused by the amplification of the electric impulses thus set up by the photo electric cell.

It is highly desirable therefore that some means be provided for eliminating this hissing noise caused by the film between sound records and the noise produced by the splices of the film. The accomplishment of these purposes forms some of the objects of my invention.

Also, it should be explained briefly, there are occasions durin the recording of sound photographically w en it is desirable to close the optical slit to the passage of light to the film. As is well known in the art, the recording of sound on sensitized film involves the changing of the sound waves to electric impulses, and imposing said impulses on the electric current which supplies the recording lamp. This recording lamp is so made as to be very sensitive to variations in current and therefore the intensity of the light from said lamp varies exactly in accordance with said electric impulses. This light of varying intensity is then passed through an optical slit past which, on the side opposite they lamp, a photographic film is moved at a constant speed. There is thus photographed on the sensitized film a sound record varying in density exactly in accordance with the sound I waves. My invention therefore includes among its objects the provision of means for shutting off the passage of 'the light to the film during such-'recording operation.

More specifically, I have provided a shutter device adapted to either cu-t o .the modulated light passing to the photo-electric cell or cut ofl the in a re roducing operation m 1n a recordactinic ight passing to the in operation.

This shutter may be automatically controlled by the film itself or it may be under the control of the operator under certain circumstances.

This device is particularly useful .iuring the recordin of sound for a motion picture, the picture lm of which has already been made. In such recording process, the picture film is projected to the screen and the sound, for instance music, is recorded simultaneous- 1 and synchronously with the rojection of the picture, said sound record ingphotoaphed on a separate strip of sensitized lm. After the sound has been recorded, it is necessary that the sound film and the picture film be matched foot for foot and frame for frame for printing together on a single film for reproduction. In order to assist'the editor in matching the sound film and the picture film, I provide means including my improved shutter for controlling the sound record in connection with the picture film. The details of this controlling device will be described later.

I also provide means whereby the shutter is controlled either by the icture film during the recording of the soun record, or by the opexator or other independent party, as desire Referring now to the drawings wherein like reference numerals indicate like parts:

Figure 1 is a front view illustrating the operation of my shutter during the reproduction of a sound film.

Figure 2 is a side view thereof.

Figure 3 is a diagrammatic view illustrating the use of my shutter during the recording of a sound record and illustrating the method of control by either the picture film in connection with which the sound is being recorded, or by independent operation.

Figure 4 is a detail view of my shutter deviole.

' 'gpx-e 5 is a detail view of portions of a lengt of film` formed for use with my shut` ter device.

Figure 6 is a. View partly in section and partly diagrammatic illustrating-the use of my shutter in connection with the reproduction of sound hoto aphically recorded.

I will first escri e my invention in connection with the reproduction of sound.

The reference numeral l indicates a support to which is secured as by the screws 2 a slideway 3 provided with grooves 4 for slidably receiving a member 5. This member 5 is hollowed as at 6 and yin alignment with the hollow portion 6 and on the opposite side of the support 1, preferably secured thereto by the same screws 2, is a tubular member 6-a adapted to receive a lamp 6b of constant intensity.' Also mounted in the tubular member 6a are suitable condenser lenses 6c through which the light from the lamp 6b passes and is focused to the opposite end of the hollow member 5 for a purpose to be described.

The member 5 is provided in its front face with an opening 7' around which is mounted a ring 8 projecting slightly beyond the face of the member 5. Mounted on the ring 8 for slight rotatable adjustment thereon is a slit holder 9 which may be secured in adjusted position to the member 5 by the screws 10. A slit member 11 preferably comprising a small prism, is' suitably secured in the slit holder 9 at a point in alignment with the opening 7, whereby the light may pass therethrough. This slit member 11 is so positioned that one apex thereof lies flush with the front face of the slit holder 9 and it is through this narrow apex of the slit member that the light passes. The film 12 is moved in any suitable manner over-,"'the face of the slit holder 9 and in engagement with the slit member 11. Film 12 carries a sound record 12a which moves past the slit member 11 thus controlling the intensity of the light passing through the film to the photo-electric cell C.

As this varying light is received by the photo-electric cell C, feeble electric impulses are set up therein corresponding to the variations in light intensity. These impulses are imposed upon an electric current supplied by the batter B and controlled by the potentiometer l'27 This modulated current is then amplified to the desired or practical degree by the vacuum tubes V, deriving their electric current from the filament battery F and the plate battery P. Three stages of amplifcation are shown, but it will be understood that more or less may be used if desired. Furthermore, it should be stated that the circuits or hook-up herein shown and described is illustrative only and in no sense limitative.

The amplified impulses are now passed to the loud speaker S where they are converted into sound waves and rendered audible.

As shown clearly in Figures 2 and 4, the member 5 is recessed as at 13 adjacent the slit holder 9 to provide a passage for the shutter 14 which may be pivotcd to one of the screws 10 and one end 14a of which lies adjacent the slit member 11 between said slit member and the light source within the member 5. The opposite end 15 of the shutter 14 provided With a roller 16 engaging with the edge of the film 12 and riding thereon. The parts are so arranged that when the roller 16 is carrier upon the edge of the film 12, the shutter 14 will be raised above the slit member 11 thereby permitting the light to pass through the film. The film 12 however is notched at predetermined intervals along its edge as at 17 whereby when one of these notches reaches the roller 16, the Weight of the shutter will cause the roller to drop into such notch, thereby permitting the end 14a of the shutter to drop down and cover the slit member 11 thus preventing the passage of light therethrough. Obviously, the notches 17 may be of any desired length, that is, in order to cause the shutter to prevent the light reaching the photo-electric cell C at all times when there is no sound record'to be reproduced, or the notches may be very short and just sufficientto permit the dropping of the shutter lfito cover the slit for an instant such as for example during the passage of a splice 18 past the slitI 11.

It will thus be seen that I have provided means for automatically controllin the passage of light through the film to t 1e photo-r electric cell during the reproducing vof a sound film, such control being effected by the film itself, thus doing away with the hissing or boomin noise produced in the loud speaker during the time when no sound record is being produced and during the passage of the splices past the slit.

In Figure 3, I have illustrated the use of my invention for sound recordin and wherein the reference numeral 19 re ers to a support corresponding to that numbered 1 in the foregoing modification. Mounted on this support 19 in a manner similar to that above described is a slit member 20`through which the recording light is adapted to pass to the film 21 which moves over the slit 20. Pivoted, as at 22 on the support 19 is the shutter 23, one end of which lies adjacent the slit 20 and the opposite end of which is secured by link 24 to an armature 25 normally pulled away from the electro-magnet 26 by means of the spring 27.

The electric circuit of the magnet 26 includes the battery 28, a switch 29, a stationary contact 30 and a movable contact 31. The movable contact 31 is carried by one end of a lever 32 having a coil spring 33 acting thereon to normally pull the contact 31 into engagement with the contact 30 thereby closing t e circuit to the electro-magnet 26. The op osite end 34 of the lever 32 carries a rol cr 35 adapted to ride on the edge of a picture film 36 thereby normally holding the contact 31 out of engagement with the stationary contact 30. The picture film 36 may be notched along its edge at predetermined points as at 37 whereby the roller 35 vupon dropping into one of said notches permits the closing of the contacts 3() and 31 and consequently the circuit of the 'electro-magnets 26 resulting in attracting the armature 25 to the magnet thus exerting a pull on the shutter 23 causing the same to move over and close the slit 20 thereby preventing the passage of light through said slit to the film 21.

Also included in the circuit of the electromagnet 26 is a manually operable key 38 which may be operated to control the shutter independently of the film 37. If desired, the switch 29 may be opened thereb elimi nating the use of the contacts 30 an 31 and the key 38 may then be use-d for controlling the 'shutter 23. Or if desired, the key 38 may be used to supplement the operation of the shutter by the automatic means provided on the film 36. 1

From this construction, it will be understood thatduring the recording of sound on the film 21, which sound is appropriate tothe picture film 36 in connection with which the sound record is being made, such recording is controlled either automatically by the picture film or manually bythe operator as desired. Theuse of the notches 37 in the picture film is helpful to the editor who subsequentlv matches the sound film and the picture lm for* printing together, as before ex lained. I

y the term optical slit, I refer to any type of slit, for t-he passage of light. The prism type herein shown anddescribed is intended as illustrative only.

Many changes in details of construction and operation will be apparent to those skilled in the art without departing from 'the sco of my inventlon. I do not limit mysel therefore, to the exact form shown other than by the appended claims.

1. In combination, a source of light, a film strip having a sound record thereon in the path of said light for varying the intensit of saidlight passing from said film in accort ance with the sound record, an optical slit through which said light passes to said film, a splice connecting oner film strip to a continuing film strip, one of said film strips being notched in advance of said splice, and shutter means operative by said notched film' strip for interrupting the passage of said light to said film when said splice passes said optical slit. i

2. In combination, a source of light, a film strip having ay sound record in the pathof said light, splices formed in said film strip, said film strip having notches in one of its edges adjacent each of said splices, an optical slit through which said light passes to said film, and shutter means for interrupting the passage of said light to said film, the operation of said shutter being controlled by the notches in the edge of said film as said splices approach said optical slit.

3'." In combination, a source of light, a film strip vhaving a sound record in the path of said light, said-"film strip having notches in one of its edges, a photo-electric cell for receiving the light passing through said film,y an optical slit between' said light and said film, and a shutter for interrupting the passage of light from the portions'of said film which are adjacent to said notches to said photo-electric cell.

4. In combination, a source of light, a film strip having a sound record in the path of l said light, said film strip having notches in one of its edges, a photo-electric cell for re- 5 ceiving the modulated light passing through said soundrecord, and a shutter for interrupting the passage of light from the portions of said film which are adjacent to said notches to said photo-electric cell.

5. In combination, a source of light, a film strip having a sound record in the path of said light, splices formed in said film, said film strip having notches in one of its edges in advance of each of said splices, an optical slit through which said light passes to said film, and a shutter between said light and said olptical slit, and electrical means operated by t e said notches for actuating the said shutter for interrupting the passage of light therethrough when said splices approach said optical slit.

6. In combination, a light, a film strip having a sound record in the path of said light, a splice connecting portions of said film, an

optical slit through which said light passes to said film, a shutter normally held out of the path of said light, and means on said film o posite said sound record for movin said shutter to interrupt the passage of said light to said film whensaidsplice approaches said slit. l

7. In combination, a light, a film strip having a sound record in the ath of said light,

a splice formed in said fi m, an optical slit through which said light asses to said film,

a pivoted shutter normalFy held out of the path of said light by an edge of said film, and

a notch on said film edge in advance of said splice whereby said shutter is operated to interrupt the passage of light to said filmduring the time interval that said splice is passing said slit.

8. In combination, a light, a movable film strip and a slit through which said light passes, a splice in said film strip, a sou-nd record on said film strip for modulating the light passing therethrough, a photo-electric. cell for receiving said modulated light, a

y shutter for automatically interruptin the passage of said modulated light to said potoelectric cell, and means for operating said shutter during the passage of said splice past said slit.

9. In combination, a light, an optical slit in the path of said light, a film strip having a sound record thereon through Which said light passes from said slit, a splice in said film, a shutter for interrupting the passage of light through said film, and means on e0 said film adjacent said splice for operating said shutter to interrupt said light during the movement of said splice past said slit.

FREEMAN H. OWENS.

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