US2092892A

US2092892A - Phonographic apparatus

Info

Publication number: US2092892A
Application number: US56884A
Authority: US
Inventors: Frank E Runge
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1935-12-31
Filing date: 1935-12-31
Publication date: 1937-09-14
Anticipated expiration: 1954-09-14

Description

Sept. 14, 1937.

F. E.'RUN'GE 2,092,892 PHONOGRAPHIC APPARATUS Filed Dec. 31, 1935 Patented Sept. 14, 1937 UNITED STATES 2,092,892 PHONOGRAPHIO APPARATUS Frank E. Runge, Oakiyn, N. J assignor to Radio Corporation of America,

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a corporation of Dela- Application December 31, 1935, Serial No. 56,884

'11 Claims.

This invention relates to phonographic apparatus, and more particularly to sound recording and reproducing apparatus of the type employing a photographic disc whereon the sound is recorded in the form of an uninterrupted spiral, the present invention being an improvement upon that disclosed and claimed in the co-pending application of Ellsworth D. Cook, Serial No. 704,605, assigned to the Radio Corporation of America.

In said co-pending application, there is disclosed a phonograph employing a record on which the sound is recorded in the form of an Archimedean spiral track, a stationary light source and associated optical system focusing a fine line of light radially across the record so as to include all the spirals or sound track turns across one radius. On the other side of the record, a stationary photoelectric cell is disposed, the active element of the cell having a' length equal to the length of the radial light line and being in alignment therewith. In order to mask off all the light except that desired at the reproducing point, an opaque mask provided with an Archimedean, transparent spiral is placed adjacent the record so that the spiral record track and the spiral in the mask will have the same geometrical center. Since the rate of radius change of an Archimedean spiral is constant throughout its length, it is possible, by choosing a scanning spiral of proper pitch and rotating it at a suitable speed relative to that of the record, to cause the two spirals to intersect each other along the aforesaid radial light line, whereby only that portion of record spiral which is in alignment with both the scanning spiral and the light line at any instant will serve to affect the light passing to the photoelectric cell at that instant.

While a-system using a scanning mask of the foregoing type works satisfactorily, it leaves open several sources of noise generation which might be serious enough, at times, to interfere with the proper reproduction of sound. In the first place, since successive transverse portions of the entire length of the scanning spiral are made 'use of during the reproduction of a record and since, even despite the exercise of great care in forming the scanning spiral, it is hardly possible to form a spiral having absolutely uniform width throughout its length, it is obvious that variations inits width along its length will result in a modulation of the reproducing beam not intended by the record. Similarly, in the case of a. scanning spiral formed on a photographic disc or plate, if dustvor other foreign matter should accumulate 5 on the transparent scanning spiral, the reproducing beam will be unintentionally modulated. Now, if this modulation takes place at a frequency within the audible range, it is obvious that unrecorded and undesirable noises due entirely to variations in width of or foreign matter upon the scanning spiral will result.

According to another well known form of phonograph of the photographic disc type, the scanning element is in the form of a disc or plate having a small aperture therein and forming a part of an optical housing which is moved radially across the record. Such a system is shown, for example, in the patent to Dirzuweit, No. 865,574. With a system of this sort, however, relatively complicated machinery is necessary to actuate not only the scanning element, but also the optical system, the light source, and the .housing and supporting structure therefor.

Moreover, a system of this sort needs continual resetting and adjustment before it can be used again once a record has been played.

of sound may be obtained without introduction of extraneous sounds along with the intentionally recorded sound.

Another object of my invention is to provide an improved record for photophonographlc apparatus of the type aforesaid, which record will itself serve to direct the sound track scanning means thereacross in a manner suitable. for scanning the sound track.

It is also an object of my invention to provide an improved record as aforesaid in which the possibility of cross-talk, or the simultaneous reproduction of two adjacent lines of the spiral sound track, is entirely eliminated.

A further object of-my invention is to provide an improved record of the type specified which will effectively set into operation, at the completion of playing thereof, suitable mechanism to cause repetition of the record.

Still another object of my invention is to provide an improved optical sound record which will permit simplification of the sound track scanning means.

A further object of my invention is to provide an improved optical sound record wherein accurate focussing' of the recording or reproducing light beam, as the case may be, will be assured.

- It is also an object of my in'vention to provide apparatus and records of the type specified which will be simple in construction and highly efficient in use. y

In accordance with my invention, I form on one surface of a transparent disc a spiral photographic record of sound or other desired pulsations, and on the opposite side thereof, I form 9,

the record may be repeated. If desired, the sec ond side of the disc (that is, the side on'which the guide groove'is provided) may be provided with a spiral, transversely-curved ridge or lenticulation adapted to act as a lens for properly focussing the light beam onto the emulsion side of the disc.

The novel features that I' consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with additional objects and advantages thereof, will best be understood from the following description, when read in connection with the accompanying drawing, in which Figure 1-is a perspective view of a reproducing system employing one form of record in accordance with my invention,

Figure 2 is a sectional view taken substantially on the line 2-2 of Figure 1,

Figure 3 is a fragmentary sectional view showing a modified form of record formed in accordance with my invention, and

Figure 4 is a view, partly in elevation and partly in section, showing a modified form' of optical housing which may be employed in connection with this invention.

Referring more specifically to the drawing, wherein similar reference characters designate corresponding parts throughout, I have shown a motor I the spindle 3 of which carries and drives a record disc 5 formed of transparent material, such as glass, and the lower surface of which may be provided with a photographic emulsion. In the specific illustration, the record disc is one which has been exposed to light fluctuations representative of sounds, for example, and subsequently developed to form an opaque spiral sound track I thereon. If desired, a plurality of rollers 6, either idling or driven at the proper speed, may also be provided to further support the disc 5 and the mechanism presently to be described,

while driving connection between the record disc 5 and the spindle 3 may be obtained in any suitable manner, as by tightly clamping the disc 5 between a collar 8 fixed to the spindle 3 and a member ,ID threaded on the upper end of the spindle.

The upper surface of the disc 5 is provided with a spiral groove 9 which is longer than and extends beyond the extremities of the sound track 1 and serves to guide a sound track scanning member H inwardly over the record as it is rotated, whereby to scan the sound track I. The guide groove 9 has a few turns 9a of fine pitch adjacent the periphery of the record disc, thereafter passes between the turns of the sound track I and has the same pitch as the sound track of Figure 1.

throughout the length thereof, and finally terminates in a closed, circular groove l3, preferably eccentric to the disc 5. A stylus or pin 15 on the scanning member ll coacts with the groove 9 to move the scanning member H inwardly, the groove turns 9a insuring proper engagement of the stylus l5 with the groove 9 in advance of the sound track 1, and the terminal groove l0 being effective to initiate, in well known manner, through an arm I! which carries the "scanning member ll, suitable mechanism for either automatically stopping rotation of the disc 5 at the end of reproduction of the record, or for resetting the stylus [5 in the groove turns 9a to repeat the record.

Light from a suitable source within the casing of the'scanning member ii is focussed at I9 on the track by a suitable optical system also within the scanning member casing and having its optical axis coinciding substantially with the center line of the track 1. After passing through the disc 5 and being modulated by the sound track I, the light strikes a stationary photoelectric cell 2| under the disc 5 which is connected to a suitable amplifier (not shown), the active element of the cell 2| extending substantially radially across the disc 5, or in line with the path of movement of the'scanning member ll over the record.

In Figure 3, I have shown a modified form of record wherein a spiral ridge or lenticulation 23 adapted to serve as a lens is formed on the surface of the disc 5 opposite the emulsion surface. The lenticular lens spiral 23 is superposed over and has the same pitch as the sound track spiral l and is provided with a suitable curvature to either focus the light on the track I by itself or to cooperate with the optical system in the scanning member casing for this purpose. Preferably, the longitudinal edges 25 of adjacent turns of the ridge,23 substantially touch each other whereby to provide a spiral stylus guiding groove 21 therebetween corresponding to the groove 9 From the foregoing description, it will be apparent that I have provided a novel record and improved photophonographic apparatus that has a number of advantages over that shown in the above-identified co-pending application of Ellsworth D. Cook, the chief of which is that the record disc does not have to be positioned accurately with respect to the scanning member. The record disc may commence rotation from any position of \rest and the sound track accurately reproduced right from the beginning by placing the guiding stylus l5 in any one of the groove turns So. Many other advantages will, no doubt, also be apparent. Also, many changes in and modifications of the invention herein described will undoubtedly suggest themselves to those skilled in the art. For example, the guide groove 9 of Figure 1 may be formed on the same surface as the sound track I, or the groove 9 and the lenticular lens 23 of Figure 3 may be formed on the lower surface of the record and the sound track on the upper surface, with a corresponding transposition of the scanning member H and the photoelectric cell 2i. However, I prefer the arrangement shown in the accompanying drawing for the reason that this prevents accumulation of dust and other foreign matter on the emulsion surface of the disc 5, and the further reason that the emulsion surface is protected against injury by the stylus [5, as by accidental placement thereon. Also, if desired, a photoelectric cell which is movable with the scanning member ll may be provided instead of being fixed, somewhat after the manner of that shown in the patent to Prescott and Kolster, No. 1,766,046. Furthermore, the stylus l5 may be made vertically adjustable in the conventional manner within a socket 29 in the housing of the scanning member II and locked 'in adjusted position by means-of a set screw 3|, as shown in Figure'4, for permiting focussing of the optical system of the scanning member I]. I desire, therefore, that my invention shall not be limited except insofar as is necessitated by the prior art and by the spirit of the appended claims.

I claim as my invention:

1. In photophonographic apparatus, the combination of a rotatable record having a spiral sound track on one surface thereof and a spiral ridge on the opposite surface thereof, said ridge having the same pitch as said sound track and being superposed thereover, the longitudinal edges of adjacent turns of said ridge subtantially touching each other whereby to provide a spiral guide groove between said ridge turns, a record scanning member associated with said record, and means associated with said scanning member and adapted to cooperate with said guide groove for causing said scanning member to be fed across said record as the record is rotated.

2. In phonophotographic apparatus, the combination of a rotatable transparent record having an opaque sound track on one surface thereof and a spiral ridge constituting a lens on the opposite surface thereof, said ridge having the same pitch as said sound track and being superposed thereover, the longitudinal edges of ad-. jacent turns of said ridge substantially touching each other whereby to provide a spiral guide groove between the ridge turns, a record scanning member associated with said record, said scanning member and said ridge lens cooperating to focus a light beam onto said sound track, and means associated with said scanning member and adapted to cooperate with said guide groove for causing said scanning member to be fed across said record as the record is rotated.

3. A sound record comprising a disc, a spiral record of sound on one surface thereof, and a spiral stylus guiding groove on the opposite surface thereof, said spiral groove having several turns of fine pitch adjacent the periphery of the disc, thereafter continuing between the turns of said sound spiral, and finally terminating in a closed circular groove.

4. A sound record comprising a disc, a spiral record of sound on one surface thereof, and a spiral stylus guiding groove on the opposite surface thereof, said spiral groove having several turns of flne pitch adjacent the periphery of the disc, thereafter continuing between the turns of said sound spiral, and finally terminating in a closed circular groove eccentric to said disc.

5. A phonograph record comprising a transparent disc, an emulsion layer on one surface of said disc adapted to have a signal representing track formed thereon, and a guiding groove on the opposite surface thereof for guiding an element'having cooperative relation with said track.

6. A sound record comprising a transparent disc, an opaque spiral sound track on one surface thereof, and spiral stylus guiding means on the opposite surface thereof, said stylus guiding means having its turns lying between the turns of said sound track.

7. A sound record comprising a transparent disc, an opaque spiral sound track on one surface thereof, a spiral stylus guiding groove on the opposite surface thereof, said spiral groove. extending beyond the ends of said sound track and being of the same pitch as said sound track throughout the length of the latter.

8. A sound record comprising a transparent disc, an opaque spiral sound track on one surface thereof, a spiral stylus guiding groove on the opposite surface thereof, said spiral groove extending beyond the ends of said sound track and being of the same pitch as said sound track throughout the length of the latter but having a plurality of turns adjacent the periphery of the disc of finer pitch than saidsound track and terminating in a closed circular groove adjacent the center of said disc.

9. A sound record comprising a transparent member having an opaque sound track on one surface thereof, and a lenticular portion on the opposite surface thereof adapted to act as a lens for focusing a light beam onto said sound track.

10. A sound record comprising atransparent member having an opaque sound track on one surface thereof, and a, lenticular portion on the opposite surface thereof in alignment with said sound track, said lenticular portion being adapted to act as a lens for focusing a light beam onto said sound track.

11. A sound record comprising a transparent disc having an opaque, spiral sound track on one surface thereof, and a spiral lenticulation on the opposite surface thereof of the same pitch as and in alignment with said sound track, said lenticulation being adapted to serve as a lens for focusing a. light beam onto said sound track and having the longitudinal edges of adJacent turns thereof substantially touching each other whereby to provide a. spiral guide groove therebetween.

FRANK E. R'UNGE.