Patent GB-390503-A (GB)
Title: A method of preparing records from which sounds may be produced and apparatus for use in carrying out the method
IPC: G11B11/00
Filed: 1931-07-30
Abstract: 390,503. Preparing sound and like records ; reproducing sound. FREUND, B., 30, Munchenerstrasse, Sch÷neberg, Berlin. July 30, 1931, No. 21813. Convention date, July 30, 1930. [Classes 40 (ii) and 88 (ii).] A method of preparing records for use in sound production consists in first making an artificial graphical representation of any desired sound wave and then transferring this representation a number of times in succession on to a film by photographic or photo-electric means so as to produce a continuous record of any desired length. The graphical representation may be of variable density or variable area type or may be a combination of both these types. For producing the continuous record, the film 1<1> bearing the graphical representation is wrapped around a rotary drum 25, Fig. 4, which contains a light source so that the representation may be repeated any number of times on to a moving film 1 by means of a lens 26 and slotted shutter 27. The film 1 and drum 25 are driven from the same source of power through the medium of sprockets 29, 30 and pulleys 31, 32 as shown. The number of times the representation is repeated per unit length may be varied by altering the speed ratio between the drum 25 and the film 1, and this alteration will effect an alteration in the pitch of the sound produced when the film 1 is passed through sound-reproducing apparatus. If desired, the speed ratio between the drum 25 and the film 1 may be varied by inserting a variable-speed gear between the film sprocket 30 and the pulley 32 driving the drum 25 as shown in Fig. 5. The variable-speed gear comprises two friction cones 90, 91 and a slidable friction roller 92 which is provided with an indicator 101 co-operating with a scale 100 indicating pitch. A further indicator may be provided for setting the duration of any particular note, and such indicator controls a number of time relayswhich are actuated selectively by moving the indicator to cause recording at the particular pitch to which the indicator 101 has been set to be effective for a definite period, after which the circuits of the recording lamp and driving motor are broken. Instead of employing a light source in the drum 25, reflected light may be used to copy the representation on the drum 25. Reproduction may also be effected by rays outside the visible spectrum. In making the graphical record allowance may be made for the known distortion produced in the reproducing apparatus. Photo-electric copying of the graphical representation may be effected by causing the latter to produce light variations which are converted into electric current variations and these are converted into light variations operating on the photographic film 1. A disc-shaped carrier may be employed for the graphical representation instead of a drum. The Specification as open to inspection under Sect. 91 describes also the following features :- (1) The artificial record may be produced by photographing a member caused to oscillate directly by the sounds ; (2) A record may be formed of a number of similar synthetic representations joined end to end with any desired spacing between them ; (3) The production of a synthetic record by photographically copying a selected part of an ordinary sound record 41 disposed on a picture film 40 on to a film 1<1> with any desired magnification or distortion by means of a lens 42 as shown in Fig. 6 (Cancelled) ; (4) The production of a synthetic record by photo-electric copying from an ordinary sound record 41, Fig. 7 (Cancelled), by means of a light source 51, lens system 52, 53, photo-electric cell 54, amplifier 55, and an optical recording system 56, 57, with the introduction of any desired distortion ; (5) A record 20 on a film 1<1> wrapped around a rotary drum 25 is reproduced by reflected light from a source 74 as shown in Fig. 13 (Cancelled) ; alternatively, the drum 25 may be transparent and the light source is then disposed inside the drum ; (6) A sound record on a film 110, Fig. 16 (Cancelled), is adapted to be reproduced by optical means and in order that the reproduced sounds may be varied in pitch the film is adapted to be driven from a motor 93 through a variable speed gear 90, 91, 92 ; (7) A number of different synthetic sound representations may be formed by means of a rotary cam 150, Fig. 20 (Cancelled), which cooperates with a number of bars 1451 so as to displace the ends of the latter to form the desired curve. The cam is adapted to be rotated to different positions according to the curve desired. Reproduction is effected by a rotary disc 153, fitted with lenses, a -lightsensitive cell 11 and a slotted shutter 154 ; (8) A musical instrument is formed by mounting a series of records 1 on a rotary cylinder 25 as shown in Fig. 17 (Cancelled) and providing each record with optical reproducing means, including a photo-electric cell 120 and switch 121 in a circuit comprising an amplifier 123 and loud-speaker 124 and also a recording device 125. By operation of one or more switches 121, sounds of desired type may be reproduced by the loud-speaker 124 or a desired record may be recorded by the device 125 ; alternatively the records may be provided in grooved or magnetic form on tracks 131 on a disc 130, Fig. 18 (Cancelled) ; (9) Consonants and vowels are recorded on tracks 161 on the surface of a cylinder 160, Fig. 21 (Cancelled) which is adapted to be driven by a motor through variable-speed gear 90, 91, 92. By suitable operation of keys 163, words can be reproduced in a loud-speaker. Certain consonants, which it is stated must be produced impulsively, are recorded on zones 171 on a second cylinder 170 which is driven by a friction gear 174 from the first cylinder 160 under the control of a ratchet wheel 172 and pawl 173. The variable speed gear 90, 91, 92 enables the pitch of the reproduced sounds to be varied. Means may be provided whereby release of -a consonant key, which has been depressed, does not occur until the key corresponding to the following vowel has been depressed. The record tracks of separate vowels and consonants for different languages may be arranged close to each other, and switches are provided for mechanically effecting the setting of the apparatus for a desired language. The impulsively-articulated consonants may be produced by pneumatic means ; (10) The record zones may be provided on a transparent cylinder 180 containing a light source 185 as shown in Fig. 23 (Cancelled), for projecting a narrow beam of light through the cylinder. A diaphragm 187 is provided with a number of openings corresponding to the record zones and any one or more of these openings may be uncovered from a keyboard to allow light-to actuate a light-sensitive cell 190 in a loud-speaker circuit ; (11) Other details, such as means for varying the volume of the reproduced sound, the use of exchangeable record carriers, the use of perforated bands for setting the keyboard instruments, the passage of a film bearing a series of pictures of an object, such as a pair of scissors, through sound-reproducing apparatus, and the combination or superimposition upon each other of a series of sound curves to produce desired effects are also described. This subject-matter does not appear in the Specification as accepted.