US1840791A

US1840791A - Process for producing an electroconductive sound wave record

Info

Publication number: US1840791A
Application number: US297333A
Authority: US
Inventors: Howard L Page
Original assignee: Individual
Current assignee: Individual
Priority date: 1928-08-03
Filing date: 1928-08-03
Publication date: 1932-01-12
Anticipated expiration: 1949-01-12

Description

H. L. PAGE I1,840,791

PROCESS FOR PRODUGING AN ELECTROCONDUCTIVE SOUND WAVE RECORD Jan. 12, 1932.

Filed Aug. 3, 1928 3 'Sheets-Sheet DUUDnnnnH-n.

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d o n Jan. 12', 1932. H, .PAGE y 1,840,791

PROCESS FOR PRODUCING AN ELECTROCONDUCTIVE SOUND WAVE RECORD Filed Aug. 3, 1928 5 Sheets-Sheet 2 @a vwentoz H. L. PAGE Jari. 12, 1932.

PROCESS FOR PRODUCING AN ELECTHOCONDUCTIVE SOUND WAVE RECORD Filed Aug. f5, 1928 3 Sheets-Sheet 5 gwn/@y 8mm/141601 Patented Jan. 12, 1932 UNITED STATES PATENT `ol-Flca HOWARD L. PAGE, oF CHICAGO, ILLrNoIs rnocnssron PRonUciNG AN Etnc'rnocoNDUcrrvEsoUNn WAVE RECORD Appncauqn med August 3,' 192s. serial no. 297,333.

This invention relates to improvements in sound records either ofthe film or pliable tape type or of' the rigid type similar for example to the phonograph disc record but will be l described herein for purposes ofillustration only with reference to the pliable tape type which may be wound on a reel like aj motion picture film for example. v

It is anV object ofthe invention to provide a. sound record, which may be produced and reproduced either separately o r synchronously, with the production or the reproduction of motion pictures. Further ob'ects of the invention are the production o sound l5 records which are electroconductiveand the reproduction of the sounds recorded on such `arecord- Itis a further object of the invention to 2 vproduce a metallic sound record which is elecproperties are utilized inthe reproduction of sound from such record.

It is another object of the invention to produce an electroconductive sound record from `tions .may easily bemade. With these and other objects in `view the invention consists v for example in a tape or film onwhich sound waves are recorded in a novel manner by a l `special photographic process. The `invention further consists of many Yfeatures and details of construction which will be hereinafter more fully described and finally pointed out in the appended claims and which areillustrated on the accompanying drawings I which form a material part of this disclosure and `in which:

Fig. 1 shows a film'provided with one metroconductive and whichv electroconductivel which aplurality of commercial 'reproduc-f ofV a collodion coated 1ilm` representing the sound 'record made by my invention.

Fig` 5 is a section similar tothat of Fig. 4 illustrating for comparative purposes the distribution of silver particles in a gelatin coated' 55 film on which a sound record has been photographed. y

Fig. ,6 is a diagrammatic plan of a camera -for photographing sound records such ash shown in Fig. 1.

Fig. 7 is a diagrammatic plan of -a camera for simultaneously photographing motion picture images and a sound record on the same film' suchY as shown in Fig. 2. Fig. 8 is a perspective view of an apparatus' suitable for producing duplicates of the f sound records shown. f

-Fig.'9 is a plan view of an original negative gelatin film with two sound wave record lines thereon. Fig-10 is a plan view of apositive master Vfilm printed from the negative shown in Fig.r9 and utilized in the making of the final sound record of this invention. Y

The sound recording cameras shown in '75 lFigs; :6 and 7 are self-explanatory to those familiar with the artand are shown as an apparatus for `producing the original sound negative which is developed in the usual way and becomes'the negative which is fixed in'f hyposulphite .of sodium solution and dried in a `suitable manner. r

Fig. 9 shows a developed negative 401 of a sound wave film. The sound Wave formation appears opaque thereon in the clear gela-755 tin ycoating of the film. From this negative a positive film 40m Fig. 10 is printed by the ordinary contact printing method on the 'usual positive gelatin coated film. This positive sound record allows light to pass through it exactly where the original sound wave photograph was Aand this film is used as a master film for the production of commercial sound record films.

The commercial sound record `films are produced in the apparatus shown in Fig, 8.

Vand when finished these records have the sound Wave lines and the base lines thereon Y in the form or nature of a metallic depositen ,the surface of the-film. The sound record film material does not need to be transparent .for reproduction of sound waves; I have used paper reinforced by cloth with good success. Only films 60 shown in Fig. 7 which have also a motion picture imprinted thereon require transparent film and these only for projection of the picture. y

The process and apparatus for producing metallic sound wave lines from the positive master film is as follows:

In a box-like housing 61, (see Fig. 8) a lamp 62 is mounted in front of a concave reflector 63 which concentrates the light from the lamp 62 onto a lens system 64 and onto the positive master lm 40m which is carried by

suitable reels

65 and 66. The light after passing through positive master film 40m is focussed through a narrow slot 67a by a lens system 67 onto a sensitized surface such as the face of film 70. This film 7() need not be transparent as mentioned before nor is a gelatin coating required.

I have secured excellent results by coating the surface of the film 7 O With other light sensitive materials such as for example a coating of collodion in which iodides or bromides of either or both cadmium or ammonium have been dissolved. While I secure good results with these materials, nevertheless, others which act in a similar way may be employed. The film strip with its prepared surface is held on a storage reel 68 in the lower part of housing 61 and passes from there under roller G9, rotatably mounted in a trough 71. This trough contains a solution of silver nitrate of suitable strength to react with the bromides or iodides carried by the collodion or other vehicle. In practice a nitrate solution of thirty grains of silver nitrate to the ounce of water has been found satisfactory. The film then passes over a roller 7 2 and while still wet receives the developable light impression from lamp 62 which has passed through master film 40m bearing the sound Wave line thereon. Reel 65 and roller 73 are suitably connected by a chain drive causing them to rotate synchronously either at thesame speed or at different speed ratios. If desired, however, the film may first be dried and then a Contact print made from the master film 40m, the exposure of the film while wet, i. e., before drying as above described being merely by way of illustration. Such dry collodion films are more fully described by E. J. Wall in his Photographic Emulsions, 1929, page 112.

A Film 70 after passing over roller 73 then passes under a roller 74 rotatably mounted in trough 75 which contains a solution of ferrous sulphate and acetic acid which develops the image of the sound wave line on the film. I have obtained good results by the use of a developer composed of thirty grains of ferrous sulphate to one ounce of water and twenty minims of acetic acid. The

record film 70 then passes over a roller 7 6 and under roller 78 which latter roller is mounted in trough 77 containing a fixing solution of sodium hyposulphite which dissolves the un` exposed silver particles, whereupon the film 70 passes out of housing 61 over roller 7 9 and under roller 80 to any suitable drying appa.- ratus.

That part of the record film 70 so produced which has been exposed as precipitated and developed thereon metallic silver, thereby producing an electroconductive metallic record of the sound wave on the film as shown in enlarged section in Fig. 4.

This action is covered in greater detail by Meldola in his work The Chemistry of Photography 4th ed., 1913, page 159; also by Abney in his Instruction in Photography 11th ed., 1905, page 32.

Fig. 5 represents a sectional elevation through a celluloid support 82 which carries the usual gelatine emulsion 83 and contains materials sensitive to light held in suspension within the emulsion. When developed with the usual alkaline developer the opaque particles representing the images are distributed or diffused throughout the total thickness of the film as indicated at c1, d2 and cl3. The electrical conductivity of such a record is negligible, the metallic particles being insulated from each other by the gelatine. The use of the acid developer above referred to is, therefore, of great and material advantage in that it enables me to produce an electroconductive sound record as distinguished from a sound record which is not electroconductive, the production of an electroconductive sound record being a desideratum of my invention.

Fig. 4 shows a similar cross section through the same sound record film of Fig. 3 when produced by my method. The support 82 carries a coating of collodion 84 upon the surface of which lies the image of the sound wave c and base lines d-dl as a coating of metallic silver the particles of which are adjacent to each other and s'o close that they form an excellent conductor of electricity, and what is of greatest importance the sound wave and base lines are all on the surface of the coating forming accessible contact surfaces Which are insulated from each other by the collodion coating 84 between them and the support 82 below them.

The metallic deposit on the supporting base may be increased in thickness if desired by redevelopment with a liquid containing a metal in solution which can be precipitated therefrom and deposited upon the metallic image. While a certain percentage of gelatine may be incorporated in the carrier or supporting base and such a film treated with the developers above referred to, the results do not seem to be improved.

The method for reproduction of sound from my metallic sound record is a very simple one as the metal of the record itself is capable of varying the current in an electric circuit.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. The process fork producin an electroconductive sound wave record w ich consists in photographically recordin sound Waves upon a transparent film, pro ucing a negative image of the sound waves by developing said film, printing a positive therefrom, reprinting said record upon a dielectric tape having a coating containing a metallic compound, and precipitating the metal from said compound on to the surface of said tape by photographic development.

Q. The process lfor producing an electroconductive sound Wave record which consists in photographically recording sound Waves upon a transparent film, producin a negative image of the sound Waves by deve oping said film, printing a positive record therefrom and reprinting said record upon a non-conduct-ive tape having a liquid coating containing silver in solution and by depositing the silver vfrom said solution upon the surface of said tape by hotographic development.

Signed at hicago, in the county of Cook and State of Illinois, this 25th day of July,

HOWARD L. PAGE.