US2888851A - Damper mechanism for piano - Google Patents

Description

June 2, 1959 c. w. ANDERSEN 5 DAMPER MECHANISM FOR PIANO Filed June 1, 1954 v 3 Sheets-Sheet l INVENTOR. 34

June 2, 1959 c. w. ANDERSEN DAMPER MECHANISM FOR PIANO 3 Sheets-Sheet 2 Filed June 1, 1954 INVENTOR. wfidflwzwlz "win/#7 June 2, 1959 c. w. ANDERSEN DAMPER MECHANISM FOR PIANO 3 Sheets-Sheet 5 Filed June 1, 1954 United States Patent Patented June 2, 1959 DAMPER MECHANISM FOR PIANO Clifford W. Andersen, De Kalb, 11]., assignor to The Rudolph Wurlitzer Company, North Tonawanda, N.Y., a corporation of Ohio Application June 1, 1954, Serial No. 433,563

Claims. (Cl. 84-217) This invention is concerned generally with the production of music, and more particularly with an electronic piano.

Throughout the history of the piano family, including the pianoforte, the harp, and the clavichord or harpsichord, tensioned springs have been used as sound generators. In the specific case of the pianoforte, commonly referred to simply as a piano, the strings are set into vibration by striking them with a hammer. Pianos and similar stringed instruments are subject to gradual detuning with time due to stretching of the strings, loosening of the string holding devices, corrosion and resulting changes in physical dimensions of the strings, temperature variations of the strings, and in the supporting and associated structures, and many other factors including variations in moisture content of wood members associated with the strings.

The aggregate string tension of a piano is very great, and may run on the order of 18 tons. In order to withstand this terrific force, piano frames commonly are made of cast iron or other strong or massive material. Thus, even the smallest pianos weigh on the order of 500 pounds With grand pianos being likely to weigh over 1,500 pounds. The physical dimensions of conventional pianos are correspondingly large, running from a minimum length of three or four feet in the direction of the strings for small pianos to as much as nine feet for grand pianos.

The large size and weight of conventional pianos precludes their being used as portable instruments in any sense. There is little room in small homes and in student practice rooms for pianos. In addition, the size of a piano requires that it be placed in a large room such as the parlor, thereby making it difiicult for a student to practice at home Without annoying other members of the family. Over and above this, it will be appreciated that pianos often cannot be used above the ground floor in homes due to the difliculty of moving them upstairs, and due to structural weaknesses of many older homes.

Vibratile reeds heretofore have been used as electrostatic tone generators, and I have discovered that when such a reed is properly shaped and dimensioned, the reed can be struck by a hammer, and the electrical oscillations generated thereby can be properly amplified and transduced to produce remarkably realistic piano tones. I have found it possible to construct an electronic piano using vibratile reed sound generators which is made up as a single unit Weighing on the order of 80 to 90 pounds, thus being readily portable, and which is quite small in size, thereby enhancing the portability and allowing my piano readily to be installed in small rooms.

An object of this invention is to provide an improved down-striking piano action of simplified and rugged construction adapted to fit in a small space, and further to provide a back acting damper in cooperation therewith to act on a small part of a tone generator of limited physical size. I

It is an object of this invention to provide suitable mechanism for simultaneously disabling all of the dampers in a portable electronic piano of the foregoing character.

It is another object of this invention to provide a foot pedal control for disabling the dampers of a portable electronic piano of the foregoing character.

A further object of this invention is to provide a portable electronic piano of the foregoing character with a damper mechanism of simple and rugged construction which is economical to manufacture.

Other and further objects and advantages of the present invention will be apparent from the following description when taken in connection with the accompanying drawings wherein:

Fig. l is a perspective view of an electronic piano constructed in accordance with the principles of my invention;

Fig. 2 is a cross-sectional view of the piano taken substantially along the line 22 of Fig. 1;

Fig. 3 is a fragmentary horizontal sectional view taken substantially along the line 3-3 in Fig. 2;

Fig. 4 is a vertical sectional view similar to a portion of Fig. 2 on a greatly enlarged scale;

Fig. 5 is similar to a fragment of Fig. 4 with the parts in a different position;

Fig. 6 is a perspective view of the damper disabling bar;

Fig. 7 is a sectional view taken along the line 7-7 of Fig. 6;

Fig. 8 is a view similar to Fig. 7 with the parts in a different position of operation;

Fig. 9 is a perspective view showing the relation of the foot pedal to the damper disabling mechanism; and

Fig. 10 is a side view of the mechanism shown in Fig. 9 and taken substantially along the line 1010 in Fig. 9.

Referring first to Figs. 1 and 2, there will be seen a portable electronic pianoidentified generally by the numeral 20. The piano includes a case 22 of Wooden construction. The case is just slightly longer than the piano keyboard, and the keyboard is of conventional length for any of the numbers of keys conventionally used in pianos, one piano constructed in accordance with the principles of my invention having a 61 note keyboard and being slightly under three feet in length. The depth of the piano approaches two feet, while the height of the case 22 is several inches less than a foot. Thus it will be seen that the piano, independent of any supporting structure, is readily portable.

The case 22 preferably is made of Wood or plywood covered with a scuff resistant material such as plastic or leatherette. The case comprises a bottom 24, a rear wall 26, end walls 28, and a top 30 extending forwardly from the rear wall 26 in parallelism with the bottom wall 24 to a position above the keyboard. At this position a cover 32 is hingedly connected to the top and extends diagonally downwardly to join a front wall 34, the cover 32 having a downturned flange 36 complementary to the front wall 34. The cover 32 opens to the dashed line position shown in Fig. 2 and coacts with a tray 37 to form a music rack when in this position. Jacks 39 (Fig. l) are provided at one end of the shelf for listening to the piano with car phones. A carrying handle 38 is provided on the front, along with locks 40 for holding the cover closed.

The case may be placed upon a desk or a table for support, or, as illustrated in Figs. 1 and 2, wrought iron legs 42 of the type currently popular for modern furniture may temporarily be attached to the under side of the case by any suitable means such as screws.

An amplifier generally indicated at 44 is carried within the case and is electrically connected to tone generators shortly to be described. The output of the amplifier is connected to a loudspeaker 46 of conventional construction carried beneath the top 30 of the case and opening through a perforated or slotted plate or grille 48 secured over an opening 50 in the top 30. The end walls 28 of the case are provided with elongated horizontal slots 52 closed at their inner sides by speaker grille cloth. These slots serve as ports for relieving back pressure on the speaker 46, and also serve as finger grips for lifting the electronic piano. A conventional power cord 54 is connected to the piano by the plug 56 for supplying electric power thereto.

Referring now generally to Figs. 2 and 3, and more particularly to Fig. 4, there will be seen a base or support 58 secured along the bottom 24 of the piano case 22. A plurality of keys 68, comprising both white and black keys for playing the whole notes and half tones, is pivotally mounted along the base or support 58 by means of a fulcrum 62 and the usual balance key pins 64, front key pins 66 being provided for stability in accordance with conventional practice. The inner end of each key is provided with a capstan screw 68. A shelf 70 at the inner end of each key and covered with a felt pad 72 serves as a damper control or release.

A main rail 74 is supported by suitable brackets 76 from the base or support 58 and extends transversely across the inner ends of all of the keys 68. It will be noted that the main rail is provided with a rectangular relieved portion 78 providing clearance for a part of the damper mechanism as hereinafter will be brought out.

A plurality of butt flanges 8G is suitably afiixed to the main rail 74, there being one such butt flange for each key, and being aligned with the keys. A hammer 82 is carried from each butt flange 88, the butt 84 of each hammer being pivotally afiixed to the corresponding butt flange as at 86. The shank 88 of each hammer projects from its butt and carries the hammer head 90 in accordance with conventional practice, the hammer head having a striker 92 of felt or other suitable or resilient material.

A spring rail 94 extends between the brackets 7 6, being mounted thereon by means such as screws 96. Spring carrying blocks 98 extend from the spring rail 94 and carry springs 190, each of which has a reversely bent tip 102 bearing beneath a forwardly projecting portion 104 of the butt 84, said forwardly projecting portion having a slot receiving the spring tip to anchor the same transversely. These springs serve to hold the hammers 82 in raised position with felt pads 106 on the under sides of the butts bearing against the capstan screws 68. A hammer rail 108 extending between raised portions of the brackets 76 is provided on its under face with a felt pad 110 providing a positive limit to upward movement of the hammers.

A generally rectangular, welded iron bracket providing a front or reed mounting rail 112, a rear or pick-up mounting rail 114, and a pair of end pieces 116 extends across the length of the keyboard and is of substantial mass to preclude vibrations. Rubber blocks 118 carried on the base or support 58 support the end pieces 116.

A plurality of vibratile metallic reeds 120 (Figs. 3 and 4) is spaced along the reed supporting rail 112 in alignment with the hammers 82. The rear, butt, or base ends of the reeds are secured to this rail by means such as bolts 122. The reeds vary in size and are provided with lead weights 124 to produce vibrational characteristics in accordance with the tones to be produced. A metallic or other conductive pick-up 126 of comb-like configuration is arranged opposite the reeds 120 and is provided with slots 128 in which the reeds vibrate. The reeds are arranged substantially in a plane with the bottom of the pick-up 126 so that when they vibrate in response to blows by the corresponding hammers, the reeds will vibrate half the time in the slots of the pick-up, and half the time below the pick-up in order to obtain proper musical tones. The pick-up 126 is spaced from the bar or rail 114 by an insulating slab 130. Bolts 132 pass 4 through insulating grommets or bushings 134 in the pickup and slabs and are threaded into the rail 114 to mount the pick-up. A shield 136 of suitable conductive material such as aluminum overlies the pick-up and also extends along the back and ends thereof electrically to shield the pick-up from stray electrical fields.

A plurality of damper lever flanges 138 is mounted along the front of the main rail 74 in alignment with the butt flanges 80 and disposed oppositely thereof. A damper lever 140 is pivotally mounted on each flange 138 as at 142, and a damper lever wire 144 extends from the front end of each damper lever and is bent up at its extremity to carry a damper block 146 having a damper pad 148 of felt or other material adapted to bear against a corresponding reed as shown in Fig. 4. A spring (not shown) encircling the pivot 142 normally biases each damper to hold its pad 148 against the corresponding reed.

At the outer end of each damper lever 140 there is provided an upstanding and bent over hook or spoon 150 overlying the damper control or release 72 on the shelf 70 of the corresponding key 60. Thus, when a key is depressed, the damper control or release 72 engages the corresponding spoon 150 to pivot the damper counterclockwise as viewed in Fig. 4 to remove the damper pad 148 from the corresponding reed. Simultaneously, the capstan screw pushes up against the butt pad 106 to start the corresponding hammer in counterclockwise rotation. When the key reaches its fully depressed position, as determined by a pad 152 (Fig. 2) the hammer has not yet hit the corresponding reed, but continues due to its inertia, the butt leaving the capstan screw, and the hammer head striker hitting the reed and rebounding therefrom to set the reed in vibration. The hammer comes to rest with the butt against the capstan screw and remains in partially depressed position with the damper retracted until the key is released, the butt spring returning the hammer and with it the key to the position shown in Fig. 4.

Means is provided for simultaneously retracting all of the dampers for'forte playing. Such means is illustrated in combination in Figs. 4 and 5, and is illustrated per se in Figs. 6-9. The damper retracting or disabling means comprises a rod 154 of circular cross section extending transversely across the piano. This rod is received in a semi-circular groove or recess 156 extending across the base or support 58, and a graphite impregnated felt strip 158 is received in this groove substantially frictionlessly to journal the rod 154. A bar 160 preferably of circular cross section but smaller than the rod 154 is welded longitudinally along the rod 154. A stop 162 projects from the rod 154 for limiting rotation thereof, and comprises a wire extending diametrically out from the rod as at 164. The wire then is angled back at an acute angle as at 166, from there projecting substantially at right angles to the portion 164 as indicated at 168, and being provided with a right angularly disposed foot in parallelism with the rod 154.

A pair of brackets 172 having arcuate portions 174 are mounted on the base or support 58 generally adjacent the opposite ends of the rod 154 and have their arcuate portions overlying said rod to maintain the same in the groove 156. A washer 176 is secured to one end of the rod 154 by means such as a screw 178, and this washer is received in a transverse arcuate groove or slot 180 for holding the rod 154 against endwise movement. A spring such as a coil spring 182 wound around the rod 154 generally adjacent the opposite end thereof serves to bias the rod in a clockwise direction as viewed in the figures of this drawing, thereby holding the portion or leg 168 and foot 170 of the stop 162 against the base or support 58 as shown in Fig. 7. In this position, as may be seen in Fig. 4, the bar 160 bears lightly against the under side of the tail of each damper lever 140, the pad 148 of each damper impinging against its corresponding reed to damp vibrations thereof. When the rod 154 is rotated a predetermined distance in a counterclockwise direction, the bar 160 cams against the under side of the tails of all of the damper levers, thereby simultaneously retracting all of the damper levers as shown in Fig. 5, the rod and bar further being shown in this position in Figs. 6 and 8. The initial Contact of the bar with the damper levers as shown in Fig. 5 precludes any lost motion and insures that the dampers all will be released simultaneously.

The damper releasing or disabling rod 154 is operated by a foot pedal 184 shown in Figs. 1 and 9. This foot pedal is arranged to reciprocate the inner or control member 186 of a push-pull control 188 of the Bowden type having also a sheath 190. The upper end of the control member 186 is afiixed to the end of a lever arm 192. This lever arm is fixed on a rod or shaft .194 which is journaled in a block 196 detachably connected to the right end 28 of the cabinet as may be seen in Fig. 10 by any releasable means such as screws or cowl fasteners, snap fasteners, or any other suitable or known fastening means. The end of the sheath 190 is connected to the block by a suitable attachment 197 of any suitable or known construction. The rod or shaft 194 is aligned with an opening 198 in the end wall 28 and is provided at its inner end with a cylindrical sleeve 200 having diametrically opposed slots 202 therein. The end of the rod 154 is aligned with the opening 198 and is provided with a cross pin 204 which is received in the slots 202, the rod fitting into the sleeve 200 when the block 196 is installed against the end wall 28. The base or support 58 is relieved at 206 in the vicinity of the end of the rod 154 to provide clearance for the cross pin 204 and for the sleeve 200.

When it is desired to play forte, it is only necessary for the pianist to depress the pedal 184, whereby to raise the lever 192 and thus to rotate the rod 154 and camming bar 160 as previously disclosed. The welding of the bar and rod together produces a rigid structure which is unlikely to bend or deflect. Furthermore, the rod 154 preferably is journaled along substantially its entire length, and consequently there can be no deflection. Thus, all of the dampers are controlled simultaneously by the foot pedal 184.

It will be appreciated that the wire construction of the damper release stop 162 is somewhat resilient, so that with the dampers on or in damping position as in Fig. 4, the bar 160 will bear resiliently against the damper levers 140, thereby precluding the possibility of any lost motion in moving the dampers to oil or released position. The removability of the foot pedal control is in line with the portability of the piano, and it will be appreciated that if it is desired to do so, the foot pedal and connecting control member can be carried on top of the keyboard beneath the cover 32.

The down-striking piano action herein disclosed is materially simplified over those conventionally used in the piano art, while the back acting dampers allow the hammers and dampers to act on the reeds at substantially the same location. This is highly desirable inasmuch as none of the reeds are very large, and the higher note reeds are quite small. Accordingly, the spacing of hammers and dampers commonly used in the piano art is out of the question.

The specific embodiment of the invention herein shown and described is for illustrative purposes only. Various changes in structure will no doubt occur to those skilled in the art, and are to be understood as forming a part of this invention insofar as they fall within the spirit and scope of the appended claims.

I claim:

1. I11 an electronic piano comprising a plurality of vibratile tone generators, having a plurality of impulse means for respectively striking said tone generators On one side thereof to cause said tone generators to vibrate, a plurality of keys for selectively operating said impulse means, and a plurality of pivotally mounted dampers respectively engageable with said tone generators on the opposite side thereof for individually damping said vibratile tone generators; means for momentarily pivoting each damper to render it ineffective as a corresponding key is depressed and means for simultaneously retracting all of said dampers, said retracting means including rotary cylindrical rod means spanning all of said dampers, spaced therefrom, and supported along its length for pivotal movement about its longitudinal axis, a radial projection comprising a cylindrical bar of greater diameter than the space between said rod means and said dampers, extending longitudinally along said rod means substantially from end to end thereof for eccentric pivoting, said rod means and said bar being secured together in radially abutting relation, means connected to said rod for pivoting said rod means to pivot said bar eccentrically whereby to force said bar against all of said dampers for simultaneously rendering all of said dampers ineffective, the support of said rod means along its length precluding deflection of said bar, and stop means projecting laterally of said rod means and engageable with a fixed part of said piano for determining the rest position of said damper retracting means.

2. The combination set forth in claim 1, wherein the rod means and bar are welded together.

3. The combination set forth in claim 1, wherein the rod means is mounted throughout its length in a recess in a fixed part of the piano.

4. The combination as set forth in claim 1, wherein the stop means comprises a wire projecting radially outwardly from said rod means, and then transversely at an angle to the radially outwardly projecting portion and being provided with an integral foot substantially parallel to said rotary rod means, said wire being resilient and providing a resilient stop.

5. The combination as set forth in claim 1, and further including a washer secured on one end of said rod means by a single screw, said washer projecting radially beyond said rod means and being received in a slot in a fixed part of the piano for axially positioning said rod means.

References Cited in the file of this patent UNITED STATES PATENTS 43,245 Vergnes June 21, 1864 447,319 Hammerle Mar. 3, 1891 670,150 Ellis Mar. 19, 1901 2,275,252 De Muth Mar. 3, 1942 2,377,582 Shill June 5, 1945 2,404,429 Brittain July 23, 1946 2,456,321 Rhodes Dec. 14, 1948 2,601,185 Bergh June 17, 1952 FOREIGN PATENTS 4,918 France May 12, 1826 4,119 France Nov. 9, 1834 7,130 France June 22, 1840

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