US2262179A - Musical instrument - Google Patents

Description

Nov. 11, 1941. L. HAMMOND 2,262,179

MUSICAL mswmmmm Original Filed July so, 1940 2 sheets-sheet 1 ax" ksflammon d Nov. 11, 1941. HAMMOND MUSICAL INSTRUMENT 2 Sheets-Sheet 2 Original Filed July 30, 1940 Patented Nov. 11, 1941 MUSICAL INSTRUMENT Laurens Hammond, Chicago, Ill.

Original application July 30, 1940, Serial No. 348,414. Divided and this application October 21, 1940, Serial No. 362,017

(Cl. 84l77) 7 Claims.

My invention relates generally to musical instruments, and more particularly to improvements in the construction of cases for electrical musical instruments.

This application is a division of my co-pending application Serial No. 348,414, filed July 30, 1940.

It is an object of my invention to provide an improved case for an electrical musical instrument in which loud speakers are incorporated, and provision is made for improved acoustic output of the speakers.

A further object is to provide an improved case for an electrical musical instrument in which the electrical parts are readily accessible for inspection and servicing.

A further object is to provide an improved case for electrical musical instruments which is of improved construction having good acoustical characteristics, in which the component parts are readily accessible, and which may be economically manufactured.

Other objects will appear from the following description, reference being had to the accompanying drawings in which:

Figure 1 is a perspective view of the instrument;

Figure 2 is a fragmentary sectional view of the instrument taken on vertical planes, one passing through the speaker, and the other behind the control panel;

Figure 3 is a fragmentary right-side elevational view with the case cover as shown in raised position;

Figure 4 is a fragmentary side elevational view showing the generator assembly in vertical position; and

Figures 5 and 6 are fragmentary details showing the electrical connections between the generator assembly and the keyboard assembly.

As best shown in Figs. 1 and 2, the instrument comprises a case consisting of a main supporting frame l0 carried by four legs l2, the bottoms of the legs at each side being joined by rung bars I4. A sound reflecting board I6 is carried by the rungs H, the support I6 also being connected to a power supply enclosure l8 and serving as a support for an expression pedal 28 and various sustaining pedals 22.

A key manual assembly 24 is mounted upon the main supporting frame III, while a control panel 26 is carried by a generator assembly designated generally by the reference character 28. A case cover comprises a pair of side walls 30, 3|, a rear wall 32, and the top 34 which are rigidly secured together and are hinged to the main supporting frame III by a hinge 36.

A music rack 38 is hinged to a front cross member 48 which is secured to the side members and 3|, therebeing an opening 4| between the rear edge of the music rack supporting member 46, and the forward edge of the top 34. A top extension plank 42 is hinged to the forward edge of the top 34, and has hinged thereto a front cover board 44. These parts 38, 42 and 44 are so conformed that when the music rack 38 is swung forwardly to a horizontal position, the boards 42 and 44 may likewise be swung forwardly so that the board 42 will form an extension of the top 34 and cover the music rack, while the front cover 44 will drop into a vertical position in front of the manual 24, thus completely enclosing the space in which the manual 24 and control panel 26 are located.

The instrument disclosed comprises a plurality of vacuum tubes 46 constituting generators and control tubes, as disclosed in my prior Patent No. 2,126,682, these tubes 46 and other electrical elements of the circuit being designated generally the generator assembly 28. As shown in Fig. 2, the tubes are supported upon a frame consisting of angle irons 48and a sheet 50, the tubes being arranged in channels extending from the front to the rear of the instrument, the channels being formed by shielding enclosures consisting of vertical sheets 52 to the upper edges of which are hinged horizontal cover sheets 54. The forward ends of the channels are closed by sheets 56, while the rearward ends thereof are closed by sheets 58. Suitable partitions 66 are provided to form electrostatic shields between adjacent groups of tubes in each of the channels.

The angle irons 48 have their ends secured to side planks 62 and 63 which are secured to the main supporting frame III by studs 64, 65, the lower ends of which are threaded in suitable sockets formed in the sides of the main frame III. A pair of similar angle irons 66, 6'! have their horizontal legs rigidly secured to the main frame l0, and have notches 66 (Fig. 3) formed adjacent their rearward ends to receive the projecting ends of lag screws 18 when the generator assembly is in its normal position, the lag screws being threaded into the side planks 62 and 63. Each of the side planks 62, 63 has a lag screw 12 threaded therein adjacent the rear end thereof. Handhole openings 14, 16 are provided in each of the side planks 62, 63.

Attached to the rearmost angle 48 of the generator assembly is a strip 18 of insulating material to which a plurality of soldering lugs 80 are attached. A similar strip 82 of insulating material is secured to a transverse board 84 which is rigid with the main supporting frame Hi, this strip 82 having a plurality of soldering lugs 88 riveted thereto. The lugs 86 are each provided with an eye portion 81 to receive the end of a coil spring 88, the other end of each of the coil springs being anchored in a hooked portion 8| of one of the lugs 80. Conductors 98 are soldered respectively to the lugs 88, and have their other ends secured to electrical elements of the generator system 28. Lugs 88 similarly have conductor 82 solder-ed thereto, which lead to electrical elements forming parts of the keying circuits of the manual 24.

When it is desired to obtain access to the underside of the generator assembly 28 the studs 64, 85 are removed, and by grasping first the right-side plank 82, the assembly is raised sufliciently to remove the lag screw 18 from its slot 68, and the assembly is swung forwardly slightly to bring the lag screw to rest in a recess 84 formed in the upper edge of the angle 88. The other side plank B3 is then similarly raised and shifted to bring its lag screw into a corresponding recess 84 in its angle 81. Thus, when slightly elevated, the generator assembly may be slid forwardly to the position in which it is shown in dotted lines in Fig. 3, the angles 86 and 81 forming guides, while the lag screws 18 rest upon the upper edges of these angle irons.

The forward sliding movement of the generator assembly is limited by the engagement of lag screws 12 with the rearward ends of the angle irons 86, 81. When the generator assembly is in this position the rearward lower corners of the side planks B2 and 53 will be in alignment with the rearward edges of notches 86 formed in the main supporting frame, so that the generator assembly may have its forward end raised and swung to a vertical position. The engagement of the lower rear corners of the side planks 62 and 63 in the notches 85 prevents the generator assembly from sliding rearwardly as its forward end is being swung upwardly. The generator assembly is swung upwardly to the posi-, tion in which it is shown in Fig. 4, in which position it is stable, and the underside of the generator assembly is available for inspection and servicing.

It will be noted, by reference particularly to Figs. 3 and 4, that as the generator assembly is moved from its normal position to its vertical position, the springs 88 are stretched and swung about, but nevertheless maintain the electrical connection between their respective lugs 80 and 88, so that even when the generator assembly is in its vertical position, all of the electrical connections are maintained and the instrument is in operative condition. Thus, testing and servicing of the instrument is greatly facilitated.

To return to the generator assembly 28 to its normal position, it is swung forwardly and downwardly from the position shown in Fig. 4 to the dotted line position of Fig. 3, in which position it is arrested and located by the engagement of its lag screws 18 with the upper edges of the angle irons 66 and B1. The generator assembly may then be pushed rearwardly until the lag screws 18 drop into the recesses 94, whereupon the lag screws 18 may be dropped into their eating notches 88. This latter operation may be performed first at one side and then at the other.

Although the generator assembly may have an aggregate weight in excess of one hundred pounds, the mounting, as described above, makes it possible for one person to swing it quite easily to the position shown in Fig. 4, and to return it to normal position. Such movement of the generator assembly is possible without disturbing any of the electrical connections between the generator assembly and the manual assembly, because of the provision of the resilient spring I connections 88 between the two assemblies.

When it is desired to remove the generator assembly from the instrument, the springs 88 may be unhooked from their lugs 88, thus very quickly and easily severing the electrical connections between the generator assembly and the manual assembly. The operation of unhooking the springs from their lugs and rehooking them when the generator is to be replaced is very simple, and avoids the necessity of breaking and remaking soldered connections, which would otherwise be necessary. It will be understood that the springs 88 are at all times under sufilcient tension to maintain good electrical contact with their supporting lugs.

In the instrument disclosed there are provided two loud speakers 96, 81 which are mounted upon sloping panels 98, the angle of the panel-s 88 being such that the acoustic beam of the loud speaker will strike the board [6, and the latter will thus reflect a large proportion of the sound energy upwardly and outwardly into the room. If the reflecting board I8 were not provided and the instrument were placed upon a rug 0: carpet, the absorption of sound by the latter would be so great, especially of the higher frequency sounds, that the music would be impaired.

The backs of the speakers are in free communication with the space within the cover of the case, and an exit for the sound waves generated by the back of the speaker diaphragm is provided by the opening ll. The generator assembly 28 does not completely fill the space within the cover, and there are numerous paths for the travel of sound through and around this assembly. This forms an excellent acoustic arrangement, since a player sitting at the manual will hear the sound produced as if it were emanating from the case itself, in the same manner that the sound from grand piano strings is in part transmitted directly from the strings and in part transmitted through the sounding board. The case itself thus provides a relatively large baille for the speakers, and also provides an acoustic reflecting surface to assure good production of the music even though the acoustic properties of the room in which it is being played are not as favorable as might be desired.

While I have shown and described a particular embodiment of my invention, it will be apparent to those skilled in the art that numerous variations and modifications may be made without departing from the underlying principles of the invention. I therefore desire, by the following claims, to include within the scope of my invention, all such variations and modifications by which substantially the results of my invention may be obtained through the use of substantially the same or similar means.

I claim:

1. In an electrical musical instrument having a manual and in which the acoustic output is produced by loud speakers, a case providing an enclosure for some of the electrical portions of the instrument, said case having an opening above the manual and having a pair of openings in its bottom, a pair of loud speakers having their diaphragms respectively closing said pair of openings in the bottom of said case, said speakers having the axes of their diaphragms directed downwardly and divergingly, and a part of said case forming relatively large hard acoustic reflecting surfaces intersecting the axes of said speaker diaphragms respectively at an angle thereto.

2. In an electrical musical instrument having a manual and in which th acoustic output is produced by loud speakers, a case providing an enclosure for some of the electrical portions of the instrument, said case having an opening above the manual and having a pair of openings in its bottom, and a pair of loud speakers having their diaphragms respectively closing said pair of openings and directed outwardly from the bottom of said case, the backs of said speaker diaphragms being acoustically in communication with said opening above the manual.

3. In an electrical musical instrument having a manual and in which the acoustic output is produced by a loud speaker, a case providing an enclosure for some of the electrical portions of the instrument, said electrical portions filling a part only of the space within said case, said case having an opening above the manual and having an opening near its bottom, and a loud speaker having its diaphragm closing said opening near the bottom of said case and directed outwardly from said case, said speaker having the back of its diaphragm open to the space within said case, 2

whereby sound radiated from. the back of the speaker diaphragm will be transmitted through the space within the case around said electrical portions of the instrument and through said opening above the manual.

4. In a case for an electrical musical instrument having a manual for controlling the acoustic output of the instrument, an electroacoustic translating means provided with a sound generator having directional characteristics, the axis of the acoustic output of said sound generator being directed downwardly and outwardly with respect to the central portion of the case, and means forming a part of said case and providing an acoustic reflecting surface intersecting the axis of the acoustic output of said generator at an angle thereto, whereby the sound produced will be reflected outwardly and upwardly from said surface.

5. In an electrical musical instrument having a manual and in which the acoustic output is produced by loud speakers, a case providing an enclosure for some of the electrical portions of the instrument, said case having an opening above the manual and having a pair of openings in its bottom, a pair of loud speakers having their diaphragms closing said openings in the bottom of said case, said speakers having the axes of their diaphragms directed downwardly, and a part of said case forming relatively large hard acoustic reflecting surfaces intersecting the axes of said speaker diaphragms respectively at an angle thereto to reflect the sound produced by said speaker diaphragms upwardly and outwardly from said case.

6. In an electrical musical instrument having a manual and in which the acoustic output is produced by loud speakers, a case providing an enclosure for some of the electrical portions of the instrument, said case having an opening above the manual and having a pair of openings in its bottom, a pair of loud speakers having their diaphragms respectively closing said pair of openings and directed downwardly from the bottom of said case, th backs of said speaker diaphragms being acoustically in communication with said opening above the manual, and sound reflecting means forming parts of said case and positioned to reflect the sound produced by the front surfaces of said speaker diaphragm upwardly and outwardly.

7. In an electrical musical instrument having a manual and in which the acoustic output is produced by a loud speaker, a case providing an enclosure for som of the electrical portions of the instrument, said electrical portions filling a part only of the space within said case, said case having an opening adjacent the manual and having an opening near its bottom, a loud speaker having its diaphragm closing said opening near the bottom of said case and facing downwardly, said speaker having the back of its diaphragm open to the space within said case, whereby sound radiated from the back of the speaker diaphragm will be transmitted through the space within the case around said electrical portions of the instrument and through said opening adJacent said manual, and means forming part of said case providing a relatively hard sound reflecting surface to reflect upwardly the sound emitted from the front of said speaker diaphragm.

LAURENS HAMMOND.

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