US2276884A - Reed structure - Google Patents

Description

March 17,1942. HQSCOTT I REED STRUCTURE Filed Oct. 19, 1939 INVENTOR Patented Mar. 17, 1942 UNITED STATES I PATENT OFFICE REED STRUCTURE Howard Scott, Wilkinsburg, Pa.

Application October 19, 1939, Serial No. 360,192

6 Claims.

The invention relates generally to reeds and more particularly to reeds for accordions.

Musical instruments such as accordions, harmonicas and reed organs, which employ for the production of musical notes a reed disposed for free vibration at its natural frequency when subjected to air pressure differentials, produce overtones and other sounds characteristic of the reed which affect the tone quality of the notes produced.

The object of the invention is to provide for controlling the flow of air through the openings in the reed plate to reduce overtones and extraneous sounds to a minimum to improve the tonal quality of the reed.

Other objects of the invention will, in part, be obvious, and, in part, will appear hereinafter.

The invention accordingly is disclosed in the embodiment thereof shown in the accompanying drawing, and comprises the features of construction, combination of elements and'arrangement of parts which will be exemplified in the construction hereinafter set forth and the scope of the application of which will be indicated in the claims.

For a general understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in conjunction with the accompanying drawing in which:

Figure 1 is a view in perspective of a base plate and reed showing a groove provided in the base plate in accordance with this invention;

Fig. 2 is a perspective view of a portion of a base plate showing in detail the groove applied to the structure of Fig, 1;

Fig. 3 is a view in perspective of a portion of a base plate showing a modifiedv type of groove;

Fig. 4 is a perspective view of a portion of a base plate showing laterally extending grooves;

Fig. 5 is a perspective view of a portion of a base plate having a fiat bottomed groove; and

Fig. 6 is a perspective view of a portion of a base plate showing a groove simulating the surface of a conic section.

Referring now to the drawing, and Fig. l in particular, a reed ID is illustrated disposed on a base plate II in alinement with an opening [2. The reed may be mounted in some suitable manner well known in the art usually by employing rivet l 3. The size of the reed. l0 and the opening l2 will depend on the notes that it is desired to produce.

The base plate and reed illustrated are only half of an accordion reed block. In the construction of an accordion, another base plate and reed would be disposed opposite the one illustrated to provide for the production of the same note upon a reversal of the air pressure and consequently direction of air flow. Details of the complete construction will not be given since this is well known in this art.

It has been found in the playing of an accordion that the air pressure waves generated do not follow a sine function, but have very sharp peaks occasioned by the abrupt cutting off of the air which results from the reed vibrating across the edges of the base plate defining the opening. It is the purpose of this invention to produce air pressure waves which follow more closely the sine function.

The operation of a reed may be described as follows. When the bellows of an accordion is operated and air flows in a direction to force the reed ll! toward the base plate, the reed will vibrate in accordance with its natural period and a note is produced having the same frequency 'as the vibration of the reed for its fundamental component. The note is produced by the puffs of air released. However, in view of the construction of. the reed and plate for a portion of the cycle air flow is cut off completely. The cutting off of the flow of air is very abrupt since it results from the reed moving into alinement with the edges of the base plate. Therefore the sound produced is not a pure sine wave because the flow of air is interrupted abruptly.

In order to reduce the portion of the cycle during which the flow of air is cut off, and also to effect the cutting off of the air less abruptly, a groove is provided in the base plate extending from the surface of the plate toward the opening it. In the embodiments of the invention illustrated the groove extends about half the depth of the base plate. However, it is to be understood that the depth of this groove and the shape of the walls defining the groove may be varied greatly depending on the conditions to be met. By conditions is meant the thickness of the base plate, the characteristics of the reed, and the-tone quality it is desired to obtain.

In the embodiment illustrated in Fig. 2, the walls M of a groove are planes and a cross-section of the groove simulates a V. In the embodiment of Fig. 3, the walls l5 of the groove are curvedand will give a somewhat different characteristic to the reed from that of the embodiment of the groove illustrated in Fig. 2. It will be readily appreciated that by varying the curvature of the walls l5 of the groove, predetermined characteristics may be given to the tone produced by the reed.

When the groove is modified as illustrated in Fig. 3, that is, when the walls of the groove are curved, eddy currents are reduced to a minimum. The curvature can readily be worked out to meet predetermined conditions.

The structure illustrated in Fig. 4 may be made to give the same characteristics as the other grooves and in some instances may be more desirable. The groove of Fig. 5 has the merit of being easy to out. It can be proportioned to give predetermined characteristics to the tone produced by the reed. Experience has revealed that the groove shown in Fig. 6 gives a very excellent tone quality.

It has been found that good results may be obtained when the walls defining the groove are sloped at about to the surface of the base plate. The depth of the groove will vary with the amplitude of the free end of the reed. The maximum depth of the groove should be approximately one half of the maximum amplitude of deflection of the free end of the reed. In the playing of an accordion With grooved plates when producing a small volume of sound the flow of air is never completely shut 01f although it may be when the maximum volume of sound is being produced. In base plates found in accordions now on the market the depth of the groove will vary from about one-thirty-second of an inch to about three-sixteenths of an inch depending on the pitch of the reed.

It has been found that grooves of this kind do not interfere to any appreciable extent with I the efficiency of a reed as a mechanical engine. The provisions of a groove at the end of the base plate increases the volume of sound at the end of the reed or tongue and the groove causes the sound to approach a sine wave. The sound caused by the escape of air along the edges of the reed is the same as ordinarily produced. The fact that there is no abrupt interruption of the flow of air and the continuing of air flow for a longer portion of the cycle improves the tonal quality of the note produced by the reed and does not reduce overtones to a degree Where the characteristic brilliance of the accordion is interfered with.

When the base plate is grooved as described, the air pressure fluctuations emanating from the groove simulates the air fluctuations of the p ysicists siren.

It has been demonstrated by the use of accordions of the same make and size and the V groove of only one set of the reeds that accordion players will readil appreciate'that one of the accordions is producing purer tones and they consistently select the one with th grooved base plates as the instrument giving the more pleasing effect. The use of grooves is particularly advantageous when applied to the middle pitch range now provided in many accordions having three or more sets of treble reeds, one set of which is one octave above and another set one octave below the middle range. The grooving is also highly effective When employed with any of the reeds including those of the highest and lowest pitch.

When an accordion is provided with grooved base plates, it will use more air at the same pressure but it also gives a greater volume of sound at that pressure. It has been found that at the same sound intensity it does not use appreciably more air and requires less effort to manipulate the bellows.

It will be readily appreciated that full chords have a much more agreeable chest and demonstrations have revealed that the notes produced from an accordion having the grooved base plates approach the piano in tonal quality, Furthermore, staccato playing of the bass notes does not cause pronounced intensity of variation of sustained treble notes as occurs in the same instrument before grooving the base plates which carry the reeds.

Since various changes may be made in the above described construction and arrangement of parts, and different embodiments may be made Without departing from the scope and spirit thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In a reed structure, in combination, a base plate having an opening extending therethrough, the opening being provided for the flow of air, and a reed disposed in alignment with the opening in the base plate, the reed fitting the opening closely enough to control the flow of air through the opening, the base plate having a groove leading from the surface into the opening to cooperate with the reed in controlling the flow of air, the maximum depth of the groove being about one-half of the amplitude of the reed.

2. In a reed structure for accordions, in combination, a base plate having an opening extending therethrough, the opening being provided for the flow of air while the accordion is being played, and a reed disposed in alignment with the opening in the base plate and above the edge of the base plate defining the opening, the reed fitting the opening closely enough to control the flow of air through the opening, the base plate having a groove leading from the surface into the opening to cooperate with the reed in controlling the fiow of air and to prevent an abrupt shutting ofi of the flow of air, the maximum depth of the groove being about one-half of the amplitude of the portion of the reed adjacent the groove.

3. In a reed structure for accordions, in combination, a base plate having an opening extending therethrough, the opening being provided for the flow of air when the accordion is being played, and a reed disposed in alignment with the opening and above the edge of the base plate defining the opening, the reed being of a size to permit it to move into the opening in the base plate as it vibrates and fitting the opening closely enough to control the flow of air, the base plate having a groove leading from the surface into the opening, the groove being provided with curved side walls and having a maximum depth of about one-half of the amplitude of the portion of the reed adjacent the groove, the groove cooperating With the reed to control the time of the shutting off of the flow of air through the opening in the base plate thereby to control the tone of the note produced.

4. In a reed structure for accordions, in combination, a base plate having an opening extending therethrough, the opening being provided for the flow of air when the accordion is being played, and a reed disposed in alignment with the opening and above the edge of the base plate defining the opening, the reed being of a size to permit it to move into the opening of the base plate and fitting the opening closely enough to control the flow of air through the opening, the plate having a groove leading from the upper level in the base plate into the opening to cooperate in controlling the flow of air, the slope of the walls defining the groove being about 45 to the upper surface of the base plate, the groove having a maximum depth of about one-half the amplitude of vibration of the portion of the reed opposite the opening.

5. In a reed structure, in combination, a base plate having an opening extending therethrough, the opening being provided for the flow of air and a reed disposed in alignment with the opening in the base plate, the reed fitting the opening closely enough to control the flow of air, the base plate having a groove provided in the portion thereof opposite the end of the reed, the groove being so shaped that as the vibrating end of the reed moves into the base plate the air flow is gradually cut off and of a maximum depth of about one-half of the amplitude of vibration of the portion of the reed opposite the groove.

6. In a reed structure for accordions, in combination, a base plate having an opening extending therethrough, the opening being provided for the fiow of air when the accordion is being played, a reed substantially rectangular in shape and presenting a plane surface disposed in alignment with the opening and above the edge of the base plate defining the opening, the reed fitting the opening closely enough to control the flow of air therethrough, the base plate having a groove leading from the upper level of the base plate into the opening to cooperate in controlling the flow of air thereby to control the tone of the note produced, the slope of the walls of the groove relative to the surface of the base plate being predetermined to give a desired rate of cutting off of the flow of air, the maximum depth of the groove being about one-half of the amplitude of vibration of the portion of the reed opposite the 20 groove.

HOWARD SCOTT.

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