US3054319A

US3054319A - Vibrato mechanism

Info

Publication number: US3054319A
Application number: US2144A
Authority: US
Inventors: Thomas B Gibbs
Original assignee: Gibbs Manufacturing and Research Corp
Current assignee: Gibbs Manufacturing and Research Corp
Priority date: 1960-01-13
Filing date: 1960-01-13
Publication date: 1962-09-18
Anticipated expiration: 1979-09-18

Description

Sept. 18, 1962 T. B. GIBBS nldl l' Y .MII l 3,054,319 Patented Sept. 18, 1962 3,054,319 VIBRATO MECHANISM Thomas B. Gibbs, Delavan, Wis., assignor to Gibbs Manufacturing 8: Research Corporation, a corporation of Wisconsin Filed Jan. 13, 1960, Ser. No. 2,144 Claims. (Cl. {i4-1.25)

This invention relates to a vibrato mechanism for a musical or electronic musical instrument.

In certain musical instruments, as in an organ, it is desirable to provide for a vibrato effect in ywhich the frequency of the tones of the instrument are varied in frequency above and below their nominal frequency -by a small percentage and at a low audio rate. `In pipe organs this is accomplished -by varying the pressure of the air used to sound the pipes.

A principal object of the present invention is the provision of an improved vibrato mechanism for an electronic musical instrument, as an electronic organ in which the tone generator or generators incorporate a moving element, the speed of which determines the frequency of the generated tones.

One feature of the invention is the provision of a mechanism including a drive source for the moving element, means including a driven element for transmitting motion from the source to the moving element, and means for advancing and retarding the driven element with respect to the drive means. Another feature is that the driving connection `between the drive source and the driven element includes a rotatable cam, rotation of which advances and retards the driven element with respect to the drive source.

A further lfeature is that a drive disc is driven from the source and a driven disc is associated with the moving element, and means including a cam interconnect the drive and driven discs together with selectively operable gear means for rotating the cam to effect the advancement and retardation of the driven disc and thus the moving element, with respect to the drive disc.

Further features and advantages of the invention will readily be apparent from the following specification and from the drawings, in which:

lFIGURE 1 is a diagrammatic elevation of a tone generator system with a vibrator mechanism embodying the invention;

FIGURE 2 is an elevation of the vibrato mechanism;

FIGURE 3 is a section taken along line 3 3 of FIG- URE 2; and

FIGURE 4 is an enlarged fragmentary section taken generally along line 4-4 of FIGURE 3.

The invention will be described herein as embodied in a musical instrument utilizing a plurality of tone generators, twelve in number, each of which utilize a rotating element in the generation of the tone representing signals. More specifically, the tone generators maybe of the type in which light is directed through openings in a mask plate and is scanned by a rotating disc, the resulting light variations impinging upon photocells in which electrical signals are generated corresponding with the desired musical tones. Further details of the tone generators themselves may be found in the Ziehlke application.

Turning now to the drawings, a tone generator drive system is illustrated in FIGURE 1 in which the twelve tone generators 10, one -for each note of the scale, are mounted on the rear surface of a panel 11. Each of the generators is provided with a pulley disc, numbered 12-23, driven by endless fbelt 25. `It will be noted that each of the pulley discs 12-23 has a diameter different than the others, the diameters being selected to produce the required frequencies for the various notes. The tone generators are driven from a constant speed motor 26 which, through `belt 27 and a driving mechanism 28 drives tone generator pulley disc 23 and thus endless belt 25.

Referring now to *FIGURES 2 and 3, driven generator disc 23 is shown mounted on a shaft-23. A second shaft 29 is journalled in a bearing 3f) carried lby a frame 311 supported from panel 11. A drive disc 34- is mounted at one end of shaft 29, preferably closely adjacent and parallel with driven generator pulley disc 23, and is directly coupled with motor 26 through belt 27. A shaft 35 is rotatably carried in bearing 36 located near the outer periphery of drive disc 34 and has an eccentrically mounted circular cam '37 at one end thereof received in a rectangular opening 38 formed in driven generator pulley disc 23. As best seen in yFIGURE 4, the sides 38a and 38h of rectangular opening 38 fit snugly with the edge surface of cam 37 so that there is no looseness or play between drive disc 34 and driven disc 23.

A planetary gear 40 is mounted on the end of shaft 35 `opposite cam 37 and meshes with sun gear 41 which is journalled on an extension of shaft 29. A pair of brake arms 42 and y43 are pivotally mounted on pin 44 extending outwardly from frame 31, and have

braking surfaces

45 and 46, respectively, which conform with the surface 41a of the hub of sun gear 41. A solenoid 47 is mounted on brake arm 42 and has an armature 47a connected -by a link 48 with brake arm 43. Solenoid 47 may be energized from any suitable source (not shown).

With

brake arms

45 and 46 released, as shown in FIG- URE 2, gears 40 and 41 rotate together as a single unit, shaft 35 is stationary relative to drive disc 34 and driven disc 23 rotates at the same rate as drive disc 34. When solenoid 37 is actuated,

brake shoes

45 and 46 engage surface 41a of the hub of sun gear 41, causing it to remain stationary while shaft 29 rotates within it. Planetary gear 40 rolls along the outside of sun gear 41, rotating shaft 35 as drive disc 34 turns. The rotation of shaft 35 turns cam 37 in the opening 38 of driven disc 23 advancing and retarding the driven disc relative to drive disc 34. The advancement and retardation of driven disc 23 relative to the constant speed of drive disc 34 is imparted to endless member 25 and through it to each of the tone generators 10 varying the frequency of the generated tones above and below their nominal frequencies. The rate of advancement and retardation of driven disc 23 is determined *by the tooth ratios of gears 40 and 41 and the rate of rotation of drive disc 34, and may be selected to provide the desired low audio rate of vibrato variations.

While I have shown and described certain embodiments of my invention, it is to `be understood that it iS capable of many modifications. Changes therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claims.

I claim:

1. In an electronic musical instrument having a tone generator with a moving element the speed of which determines the frequency of the generated tone, a vibrato mechanism, comprising: a drive source for said moving element; and means providing a driving connection between said source and said driven element, said means including a cam driving connection, rotation of said cam advancing and retarding a driven element with respect to said drive source. i

2. In an electronic musical instrument having a ton@ generator with a moving element the speed of which determines the frequency of the generated tone, a vibrato mechanism, comprising: a drive source for said moving element; means providing a driving connection between said source and said driven element, said means including a cam driving connection, rotation of said cam advancing and retarding a driven element with respect to said drive source; and selectively operable gear meanS for driving said cam.

3. In an electronic musical instrument having a tone generator with a moving element the speed of which determines the frequency of the generated tone, a vibrato mechanism, comprising: a drive source for said moving element; a drive disc rotated by said drive source; a driven disc operably associated with said moving element; means including a cam connecting said drive and driven discs; and gear means for rotating said cam to advance and retard said driven disc with respect to said drive disc.

4. In an electronic musical instrument having a tone generator with a moving element the Speed of which determines the frequency of the generated tone, a vibrato mechanism, comprising: a drive source for said moving element; a drive disc rotated by said drive source; a driven disc operably associated with said moving element; a shaft journalled in said drive disc; a cam on one end of said shaft and received in a slot formed in said driven disc; a planetary gear at the end of said shaft; a sun gear mounted for rotation coaXially with said drive disc; and means for restraining rotation of said sun gear, said cam being rotated by said planetary gear and advancing and retarding said driven disc with respect to said drive disc.

5. In an electronic musical instrument having a plurality of tone generators with respective driven pulley discs the speeds of which determine the frequencies of the generated tones and having an endless belt for frictionally driving the discs, a vibrato `mechanism comprising: a drive means, a drive pulley disc rotated by said drive means and positioned adjacent to and coaxial with one of the driven pulley discs; means including a cam connecting said drive disc and said one driven pulley disc; a sun gear rotatable with the drive pulley disc; a planetary gear meshed yWith said sun `gear and connected to said cam; and means for restraining said sun gear causing rotation of said cam with respect to said drive pulley disc, advancing and retarding the one driven pulley `disc With respect thereto.

References Cited in the file of this patent UNITED STATES PATENTS 2,746,334 Williams May 22, 1956 FOREIGN PATENTS 656,792 Great Britain Sept. 5, 1951