US 3334174 A
Description (OCR text may contain errors)
Aug. 1, 1967 TAKE@ sHlGA ETAL 3,334,174
ELECTRONIC MUSICAL INSTRUMENT n Filed Aug. 21, 1964 5 sheetsheet 1 PAP/OP A27' PR/Ol? IQT M/cA//o O/(AMoro A TTORNE YS Aug. 1, 1967 TAKE@ sl-HGA ETAL 3,334,174
ELECTRONIC MUSICAL INSTRUMENT Filed Aug. 2l, 1964 5 Sheets-Sheet 2 Lm G m if of', .4.;
INVENTOR ELL/ao .SH/@A Saleem/ 4 M/As//ZA w.4 l voeu 5105474 .py I G/M/ ATTORNEYS Allg l 1957 TAKE@ SHIGA ETAL 3,334,174
ELECTRONIC MUSICAL INSTRUMENT Filed Aug. 2l. 1964 5 Sheets-Sheet 5 INVENTORS 721 eo 5,#/64 MCH/o O15/:Mo To A TTORNE 'YS Aug. 1, 1967 Filed Aug. 2l; 1964 5 Sheets-Sheet 4 I NVENTOR 72x50 .5H/GA /l//fc/f/o Ummm-ro .SH/seran: WASH/mwa Aug. l, 1967 TAKE@ SHIGA ETAL ELECTRONI C MUS I CAL INSTRUMENT Filed Aug, 2l. 1964 5 Sheets-Sheet 5 5b uhm) Q Q Q Q Q D Q LQ INVENTOR UnitedStates Patent Office 3,334,174 Patented Aug. 1, 1967 3,334,174 ELECTRONIC MUSICAL INSTRUMENT Takeo Shiga, Michio Okamoto, Shigetaka Washizawa, and Minoru Shibata, Kawasaki-shi, Japan, assignors to Nippon Columbia Kabushikikaisha (NipponColumbia Co., Ltd.), Kawasaki-shi, Japan, a corporation of Japan Filed Aug. 21, 1964, Ser. No. 391,096 Claims priority, applicatiorllpan, Aug. 24, 1963,
This invention relates to electronic musical instruments, more particularly to vibratory pickups for use in such electronic musical instruments.
There have recently been proposed improvements in or relating to electronic musical instruments which electrically produce musical tones similar to those of string instruments such as a piano, guitar and the like and wind instruments such as, for example, a flute and other instruments.
In the electronic musical instrument such, for example, as an electronic piano, many vibratory pickups are provided in response to the number of strings of a usual or an actual piano. These pickups are usually arranged in the following manner. That is, vibratory electrode plates are disposed respectively opposite to fixed electrode plate vibrates by being struck with a hammer. Electric capacitance established between the vibratory electrode plate and the fixed electrode plate is varied with the vibration and voltages of oscillation frequencies due to the vibration are led out which correspond to those of the respective piano strings and then these voltages are applied t-o an amplifier, thus producing musical tones similar to those of the piano strings.
In such an electronic piano, however, the harmonic distribution of the voltages produced by the vibratory pickups is not always similar to that of the usual piano. Furthermore, we found iu our experiments that an output damping characteristic of such vibratory pickups does not always coincide with the damping characteristic of the respective strings of the ordinary piano. Accordingly, we noticed that it would .be difiicult to provide an electronic piano having acoustic characteristics similar to those of vthe vusual piano, unless the aforementioned harmonic characteristic and damping characteristic are taken into account.
Accordingly, one object of this invention is to provide vibratory pickups each having a harmonic distribution which corresponds to that of each vibratory member of an instrument to be attained.
Another object of this invention is to provide vibratory pickups each having a damping characteristic which is extremely similar to that vof each vibratory member of an instrument to be attained.
Still another object of this invention is to provide van electronic piano having vibratory pickups which are capable of picking up acoustic characteristics consisting of a desired harmonic distribution and damping characteristic of respective vibratory members of an instrument to be attained.
A yfurther object of this invention is tol provide an electronic piano provided with vibratory pickups each having both a harmonic distribution and damping characteristic which are similarto vibratory characteristics of each string of a usual piano.
A still further object of this invention is :to provide in a mass-production manner fixed electrode pla-tes of the vibratory pickups for such electronic musical instruments, which plates are so formed as to afford a harmonic distribution and damping characteristic of an ordinary piano.
Other objects, features and -advantages of this invention will be apparent from -the following description `taken in conjunction with the accompanying drawings, in which:
FIGURE 1 is a front view illustrating an example of a pickup for an electronic musical instrument heretofore employed;
FIGURE 2 is its side view;
FIGURE 3 is a harmonic distribution diagram illustrating an output harmonic distribution of a vibratory electrode plate with respect to its vibrating time, which electrode plate constitutes a pickup of an electronic piano employing conventional pickups such as shown in FIG- URES l and 2;
' FIGURE 4 is a harmonic distribution diagram illustrating a harmonic distribution of a string of a usual piano with respect to its vibrating time;
FIGURE 5 is a schematic front view of a pickup of an electronic piano according to this invention;
FIGURE 6 is its side view;
FIGURE 7 is a front view of a fixed electrode plate,
. for explaining a structure of a fixed electrode plate of the pickup shown in FIGURES 5 and 6;
FIGURE 8 is a graph illustrating variations in electric capacitance with respect to the fixed electr-ode plate when a vibratory electr-ode plate vibrates, and for explaining the variations in comparison with a damping curve of an amplitude of the vibratory electrode plate;
FIGURE 9 is a diagram illustrating an envelope waveform of an output voltage produced due to the vibration of the vibratory electrode plate;
FIGURE l0 is a damping characteristic diagram illustrating, in the form of an electric output, variations in an output of a string of the usual piano with respect to its vibrating time;
FIGURE ll is an envelope damping characteristic diagram illustrating variations in a voltage amplitude of a pickup of the electronic piano of this invention with respect to time, similar to FIGURE 10;
FIGURE 12 is a graph illlustrating a damping characteristic of the vibratory electrode plate of this invention and an electric capacitance curve which determines variations in electric capacitance established between the fixed electrode plate and the vibratory electrode plate which are to draw on the fixed electrode plate by combining the damping characteristic and that shown in FIGURE 1l;
FIGURE 13 is yan enlarged front view of the fixed electrode plate shown in FIGURE 7;
FIGURE 14 is an enlarged diagram illustrating a pracl tical pattern of a harmonic distribution;
FIGURE l5 is a diagram illustrating a practical pattern with the harmonic distribution and the damping characteristic distribution added thereto;
FIGURE 16 is a harmonic distribution diagram of a pickup of an improved elec-tronic piano according to this invention; and
instrument, particularly in an electronic piano will hereinbelow be explained with reference to FIGURES 1 and 2. 1 -is a fixed electrode plate of a vibratory pickup attached to a frame 2 of, for example the electronic piano. 3 is a vibratory electrode plate placed opposite to the fixed electrode plate 1 with 'a slight gap g therebetween. The vibratory electrode is struck by a hammer associated with a key of the electronic piano, both being not shown, and performs a damped oscillation as shown by the dotted line to change the gap g, varying electric capacitance established between the both electrodes 1 and 3. Thus, desired electric oscillating output voltages are obtained in accordance with the variations in the capacitance. t1 and tzvare terminals to be connected to the electric oscillator circuit.
In the electronic piano such vibratory pickups have their particular vibrations each corresponding to that of each string of the usual piano, and many vibratory pickups of Isuch character are disposed between the frames 2 and 2 and hammers of the electronic piano are arranged for such pickups.
Considering the harmonic distribution of the conventional electronic piano using such vibratory pickups, the characteristic of a vibratory pickup of bass is as shown in FIGURE 3, in which the abscissa expresses a vibrating time t of the vibratory electrode plate 3 and the ordinate represents the frequency f of a voltage caused by the vibration. In FIGURES 3, 4 and 16 the width W shows a vol-tage at that time, the broken portion shows zero voltage and the amplitude variation shows frequency variations. It is noticed that the frequency distribution gradually decreases with an increase in frequency. On the other hand, the harmonic distribution, converted into electrical output voltage of the vibration of a string of the ordinary piano corresponding to the pickup above mentioned, is as illustrated in FIGURE 4. That is, in FIG- URE 4 the abscissa represents a vibrating time t of a string of bass and the ordinate represents the frequency f produced by the vibration. As is apparent from the ligure, there are contained many harmonics even in a lower frequency zone and these harmonics continue for a considerably long t-ime. In comparison with the harmonic distribution shown in FIGURE 3, that illustrated in FIG- URE 4 includes higher harmonics and their duration of time is longer. It has been found from the above comparison that the characteristics, especially tones of the conventional elec-tronic piano are inevitably diiferent from those of the usual piano for the reason that the higher harmonics in the electronic piano are less than in the ordinary one.
On the basis of our study described above, the present invention is to provide an electronic piano having harmonic distribution characteristics which are as similar to those of a usual piano as possible.
FIGURE 5 illustrates a front view of a vibratory pickup of the electronic musical instrument of this invention and FIGURE 6 shows its side view. FIGURE 7 illustrates a front view of a iixed electrode plate shown in FIGURE 5. Parts corresponding to those in FIGURES l and 2 are marked with the same numeral references. In the illustrated example an insulating plate 4 is used, `as a fixed electrode plate, on the surface of which is provided an electrode sur-face, namely a conductive portion 6 having a pattern 5 in accordance with the component rate of harmonies such as described later. Opposite to the fixed electrode plate, the end of a vibratory electrode plate 3 is placed and vibrated. In order to form the electrode .surface 6 on the surface of the insulating plate 4, it is possible to apply an etching method normally used for making printed-'wiring boards. According to this method, a plurality of similar electrode plates can be mass-produced. It has also been found that the damping characteristic when the lfundamental frequency and its harmonics are produced must be as similar to that of the corresponding string of the usual piano as possible in order that the electronic piano may produce tones similar to those of y the usual piano. FIGURE 8 illustrates a relationship between a damping envelope curve of the amplitude of the vibratory electrode plate with respect to time t and variations in the electric capacitance in a vibratory pickup of such an electronic piano as described above. That is, the damping envelope of the vibratory electrode plate is as shown by the curve a and the variation in the electric capacitance Co is as shown by the curve b. In the case where such a vibratory pickup as described above is employed, the variation in the voltage amplitude, namely the output voltage envelope of the vibratory pickup is as shown l by the curve c in FIGURE 9, .the abscissa expressing time t and the ordinate output voltage v. Comparing the damping` envelope a and the envelope c of the output voltage p in FIGURE 8, the envelope c is gentler than that of a.
On the other hand, the damping characteristic of the string of a usual piano corresponding to the aforesaid vibratory pickup is as illustrated in FIGURE l0, the absc-issa representing time t and the ordinate voltage v that tone has been converted into electrical output. That is, the curve d shows variations in the output Voltage v, namely the damping characteristics of the ordinary piano. The envelope c representative of the vibratory pickup of the electronic piano such as shown in FIGURE 9, is greatly diierent from the envelope d showing .the damping characteristic of the usual piano. As is apparent from the two figures, the envelope d of the usual piano shows that the output abruptly decreases with the lapse of time, while the envelope c of the electronic piano shows that the output varies only very slowly. This is `one of the reasons that the tones of the electronic piano diifer from those of the ordinary piano. In the present invention it is very important to make the envelope c as similar to the envelope d of the usual piano shown in FIGURE 10 as possible.
FIGURE 11 illustrates an envelope curve e plotted after the damping characteristic d of the usual piano shown in FIGURE l0. It is, of course, desirable that a vibratory pickup of the electronic piano corresponding to a certain string of the ordinary piano presents such a damping characteristic e as shown in FIGURE 1l which is similar to that in FIGURE 10. Since the damping characteristic of the vibratory electrode plate 3 of the vibratory pickup can be shown by the damping curve envelope a: as explained in FIGURE 8, the electric capacitance established by the conductive portion 6 and the vibratory electrode plate 3 is desired to be varied with the vibration of the vibratory electrode plate 3 in such a manner that the vibratory pickup may have the amplitude damping characteristic e such as shown in FIGURE l1 in accordance with the damping curve envelope a. From the curves a and e respectively in FIGURES 12 and 11, variations in the electric capacitance established by the vibration of the vibratory electrode plate can be drawn in the form of the curve h in FIGURE 12. That is, the area surrounded by the curve h, the abscissa and the ordinate can be so selected as to attain the object described above. In other words, by determining the area of the conductive portion 6 in accordance with the aforementioned area, a vibratory pickup can be obtained which has damping characteristic similar to that d of the corresponding string of the usual piano. Accordingly, it is possible to make an electronic piano which is provided with vibratory pickup each having damping characteristic similar to that of the corresponding string of usual piano as described above.-
FIGURE 13 is an enlarged diagram of FIGURE 7. The pattern 5 is greatly related to the component rate of harmonics and its practical pattern is as illustrated in FIGURE 14. If the crests P1, P2 and the troughsV Q1, Q2 are continuous in FIGURE 13, a pattern is considered such that the crest P and the trough Q are linked with a straight line as shown by the dotted line. In this case, however, higher harmonics can be included by affording some curvature between P and Q as shown by the solid line. The ditference between the adjacent crest P and trough Q, namely the height L is related to the le'vel of the harmonics. The vibratory electrode plate 3 stands still on the X--X axis and when struck by a hammer it vibrates right and left with respect to the axis X-X and opposite to the conductive portion 6 having the pattern. D shows a range of the vibration of the vibratory electrode plate 3. The vibratory electrode plate 3 starts to vibrate with a maximum amplitude and gradually damps and finally comes to a standstill on the predeterminel X-X axis. However, since the Vamplitude of the vibratory electrode plate 3 varies due to the damped vibration, the position of the electrode plate 3 to the pattern formed on the conductive portion 6 differs in response to amplitude variationsl The component rate of a desired nth harmonics varies with the amplitude. That 5 is, the vibratory electrode plate 3 vibrates right and left from the axis X-X with its peculiar frequency but the amplitude damps and accordingly the component rate of -a desired nth harmonics varies with time in response to the damping. In accordance with the present invention the contour of the conductive portion 6 is selected in such a manner that the fundamental frequency and its harmonics caused due to the vibration of the vibratory electrode plate 3 may be similar to the harmonic distribution of the usual piano such as shown in FIGURE 4. That is, the crest P and trough Q are formed so as to be as similar to the harmonic distribution of the corresponding string of the usual piano as possible. The pattern 5 is not always required to be continuous, for example it can be discontinued by a space d at the trough Q. Since the difference in height, namely L between the crest and trough isrelated to the level of the harmonics, the height L is selected so that the level of the harmonics caused by the vibratory electrode plate may be as similar to that of the usual piano as possible.
In the present invention the pattern on the conductive portion 6 is formed along the curve h in FIGURE 12 as illustrated in FIGURE 7 or 15. When the vibratory electrode plate 3 vibrates opposite to such a conductive portion 6 the amplitude damping of its output is suzstantially equal to that shown in FIGURE 11 and accordingly this output damps in response to the curve d of FIGURE 1() illustrating the output damping characteristic of the ordinary piano, and further the desired harmonic distribution is caused as .described in the foregoing. Therefore, it will easily be seen that the vibratory pickup of this invention is similar to that of the ordinary piano in the harmonic component rate as Well as the damping characteristic. FIGURE 16 illustrates an example of the harmonic distribution characteristic of the vibratory -pickup made as described above according to this invention, in which the abscissa expresses time t and the ordinate frequency f. Comparing the harmonic distribution shown in FIGURE 16 with that in FIGURE 4, the harmonic component rate is very similar to that of the ordinary -piano and the damping characteristic is substantially equal to that shown in FIGURE 10, as is apparent from the foregoing.
Furthermore, at least one portion of the contour of the envelope on the conductive portion v6 shown in FIG- URE 7 is formed along the curve h illustrated in FIG- URE 12. It must also be noted that the aforementioned pattern 5 is formed along this curve.
In the foregoing only one vibratoryv pickup of the electronic piano of this invention has been described, but other pickups are also formed in the same manner, That is, the pickups are respectively provided with the harmonic distribution characteristic and damping characteristic which are similar to those of their respectively corresponding strings of the usual piano. Accordingly the electronic piano having such respective vibratory pickup has in its overall characteristics the damping characteristic and frequency distribution characteristic which resemble those of the usual piano and such electronic piano produces tones which are similar to those of the ordinary piano. By suitably changing the envelope e and the pattern 5 on the conductive portion, the vibratory pickups are provided with any desired harmonic characteristic and damping characteristic, and hence it will easily be seen that a unique electronic piano or other electronic musical instruments which are different even from a usual piano can be obtained.
In the foregoing example a specific vibratory pickup has been described such that a pattern -is formed on the conductive portion of the fixed electrode plate 1 placed opposite to the vibratory electrode plate 3. Instead of this pattern, a lamination composed of a plurality of conductive plates 8, which correspond in width to the crest portion P and are insulated each other by insulating plates 9, is connected to a same current collector,
namely a conductive member 10 as illustrated in FIG- URE 17, by which the pickup can also operate in the same manner as in the foregoing example. Where there is no need of forming the crest portion P .and the trough portion Q,it is possible to assemble the fixed electrode plate 1 by laminating a plurality of the conductive plates 8 of the same width being insulated from each other.
The foregoing has been made in connection with an example in which the vibratory electrode plate 3 has a simple surface and the conductive portion such as described above is used as the fixed electrode plate. However, it is possible that an electrode plate 6 having a conductive portion such as illustrated in FIGURE 7 is employed .as a vibratory electrode plate while the fixed electrode plate of simple shape is used. Otherwise, it is also possible to use such a pickup which is composed of a fixed electrode plate and a vibratory electrode plate having complicated conductive portions similar to the conductive portion 6 described above.
In FIGURE 17, the conductive plates 8 are respectively insulated by the insulating layers 9 but they are electrically connected to the common current collector 10. In such a case the conductive plates 8 have a straight or curved face 11, but where the conductive plates 8 are projected alternately in the form of teeth the insulating layers 9 are unnecessary.
When the vibratory electrode plate 3 vibrates to the right and left, opposite to the conductive face 6 of the fixed electrode plate 1 which lies on the surface of the paper, the fixed end of the vibratory electrode plate being its center of vibration, as shown in FIGURE 7, the gap g between the vibratory electrode plate and electrode portion 6 varies in response to the amplitude variation of the vibration from the center axis X--X and the variations of fthe electric capacitance C0 cannot be uniform at every part. To compensate this, the conductive portion 6 is curved to be positioned on a circular arc about the fixed point of the vibratory electrode plate 3. Thus, the variations of the electric capacitance can be made uniform at the respective parts. Where the compensation such as the aforementioned one is carried out on the pattern, the conductive portion of the pattern can be changed in parallel to the X-X axis so as to compensate the abovementioned unequal portions at the respective parts except the center of the vibratory electrode plate.
It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concept of this invention.
What is claimed is:
1. An electronic musical instrument comprising:
a plurality -of vibratory pickups each lhaving a vibratory electrode lplate and a fixed electrode plate spaced opposite thereto, said fixed electrode -plate having formed thereon a first contour and a second contour cooperable with said first contour so as to give a specific effect to the sound generated from said electronic musical instrument.
2. An electrode musical instrument according to claim 1 wherein said second contour corresponds to a damping characteristic of the musical instrument.
3. An electronic musical instrument according to claim 1 wherein the confronting face of said fixed electrode plate is concave in such a manner as to form a uniform gap between said fixed electrode plate and the free end of said vibratory electr-ode.
4. An electronic musical instrument comprising:
vibratory pickups each having a vibratory electrode plate and a fixed electrode plate spaced opposite Ithereto, said fixed electrode plate having a conductive pattern formed on an insulating plate attached to said fixed electrode plate, said conductive pattern having crest and trough portions and a curve of a suitable curvature formed between said crest and trough portions in such a manner as to obtain a voltage containing harmonics similar to the harmonic rate of the corresponding vibratory member of a musical instrument to be obtained.
5. An electronic musical instrument according to claim 4 wherein s-aid crest and trough Iportions are formed along said curve.
6. An electronic musical instrument according to claim 4 wherein said conductive portion consist of a plurality of conductive plates electrically insulated from one another by insulated layers, said plurality of conductive plates being electrically connected together.
7. An apparatus for electronically producing sound having the same tone qualities as Ia musical instrument, comprising:
vibratory pickup means including:
a vibratory electrode, a fixed electrode mounted in close proximity with said vibratory electrode, the improvement therein comprising means including a plurality of contours formed on said pickup means to electronically produce sound 8. An apparatus for electronically producing sound having the same tone quality as a musical instrument, comprising:
vibratory pickup means including, a vibratory electrode having a stationary end `and a movable free end;
a fixed electrode mounted in close proximity to the free end of said vibratory electrode; the improvement therein comprising, rst and second contours formed on said fixed electrode, whereby, said iirst and second contours cooperate to electrically produce sound having the same tone quality as a musical instrument.
References Cited UNITED STATES PATENTS 15 2,532,038 11/1950 Sebouh 84--1.14X
lhaving the same tone qualities as the musical in- 2 strument.
1/1952 Langloys 84-1.15 X 10/1953 Miessner 84-1.14
UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION 3,334, 174 Dated August l, 1967 Patent No.
) Takeo Shiga et al Inventor(s It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Col. 8, after line 16, insert 3,038, 363 6/62 Miessner 84-1. 14
Signed and sealed this 10th day of August 1971.
EDWARD M.FLETCHER,JR. Attestng Officer WILLIAM E. SCHUYLER, JR. Commissioner' of Patents FORM IDO-1050 (1o-69) uscoMM-oc Goan-peo U.5. GOVERNMENT PRINTING OFFICE: N69 D-BiG-JM