Electric percussion instrument with a vibration sensor attached to a vibration transmitting holder

Abstract: A pad member (12) of an electric percussion instrument is supported through a cushion member (16) by a case member (11) for isolating the pad member from noise produced in the case member upon strikes of the pad member, and a vibration sensor (15) is connected with the pad member (12) by means of a holder (13/14) of vibration transmitting substance so as to propagate the vibrations of the pad member to the vibration sensor without any influence of the noise.

Description: FIELD OF THE INVENTION This invention relates to an electric percussion instrument and, more particularly, to an electric percussion instrument equipped with a vibration sensor supported by a retainer of vibration-transmissive substance. DESCRIPTION OF THE RELATED ART A typical example of the electric percussion instrument is disclosed in Japanese Utility Model Publication of Unexamined Application No. 59-39753, and comprises a tubular member with an inner space, heads covering both ends of the tubular member and a cushion member of porous substance such as sponge filling the inner space and a vibration sensor of a piezo-electric element embedded in the cushion member. The vibration sensor is adjusted to a center of the inner space, and the cushion member is expected to isolate the vibration sensor from forced vibrations of the tubular member. In a performance, while a player is beating the head, not only the head but also the tubular member vibrate at respective characteristic frequencies, and the cushion member takes up the forced vibrations of the tubular. As a result, the vibration sensor is expected to detect the vibrations of the head. The vibration sensor produces an electric signal indicative of the vibrations of the head, and a speaker system reproduces the sound from the electric signal. However, the cushion member takes up not only the vibrations of the tubular member but also the vibrations of the head, and the vibrations at a soft beat are too weak to be detected by the vibration sensors. This means that soft beats are liable to be lost in the reproduction of the sounds. GB-A-2 192 087 discloses an electronic drum having a cushioning member located within a case member. The cushioning member elastically supports a cushioning/vibration composite plate retaining a sensor. The cushioning/vibration composite plate consists of an upper cushioning rubber sheet and a lower cushioning rubber sheet and damps the strike force applied. Since the cushioning/vibration composite plate is a composite plate the cushioning layers cannot be adjusted depending upon the magnitude of impacts exerted on the drum head or pad. This means that soft beats are likely to be lost in the reproduction of the sounds. FR-A-2 544 115 discloses an electric percussion instrument avoiding the pick up of noise from the envirement. The electric musical instrument comprises a case member, a pad member, a sensor retained by a retainer and a cushion means. If a player beats the pad member softly at a rather peripheral portion the sound production may be lost easily. FR-A-2 602 607 refers to an acusto-electrophonic musical instrument having a retainer, carrying a sensor and comprising a plurality of stud members fixed to a pad member and a sensor board fixed to said plurality of stud members and supporting said vibration sensor. If a player beats the pad member softly at a rather peripheral portion the sound production may be lost easily. SUMMARY OF THE INVENTION It is therefore an important object of the present invention to provide an electric percussion instrument which faithfully detects vibrations without any influence of forced vibrations of a case member. To accomplish this object an electric percussion instrument is provided comprising the features mentioned in claim 1. BRIEF DESCRIPTION OF THE DRAWINGS The features and advantages of the electric percussion instrument according to the present invention will be more clearly understood from the following description taken in conjunction with the accompanying drawings in which: Fig. 1 is a cross sectional view showing the structure of an electric percussion instrument which does not represent the present invention but is included for the sake of illustration and better under standing. Fig. 2 is a front view showing a pad and a sensor board incorporated in the electric percussion instrument; Fig. 3 is a plan view showing the pad and the sensor board; Fig. 4 is a cross sectional view showing an electric percussion instrument according to the present invention; and Fig. 5 is a bottom view showing a vibration sensor supported by a sensor board incorporated in the electric percussion instrument shown in Fig. 4. Illustrative Example Referring first to Fig. 1 of the drawings, an electric percussion system is comprises a case member 11, a pad member 12, a sensor board 13, a plurality of stud members 14, a piezo-electric element 15 and a cushion member 16. In this instance, the sensor board 13 and the plurality of stud members 14 as a whole constitute a retainer, and the piezo-electric element 15 serves as a vibration sensor. The case member 11 has a bottom portion 11a and a wall portion 11b merged with the bottom portion 11a, and, accordingly, the case member 11 forms a hollow space 11c therein. The pad member 12 is implemented by a pad plate 12a formed of iron and partially covered with rubber. The rubber film 12b protects an upper surface of the pad plate 12a against impacts at beats by a player, and exposes a central area of the back surface of the pad plate 12a. The sensor board 13 is formed of a vibration-transmissive substance selected from the group consisting of iron and acrylonitrile-butadiene-styrene resin, and is fixed to the exposed central area of the back surface of the pad plate 12 by means of the plurality of stud members 14. The plurality of stud members 14 are also formed of the vibration-transmissive substance, i.e, either iron or acrylonitrile-butadiene-styrene resin, and the plurality of stud members 14 and the sensor board 12a well propagate vibrations produced in the pad plate 12a to the piezo-electric element 15. The plurality of stud members 14 are connected between the exposed area of the pad plate 12a and a peripheral area of the sensor board 13 as shown in Fig. 2, and may be fixed to predetermined locations on the sensor board 13 where the nodes of composite vibrations take place. Each of the plurality of stud members 14 is angularly spaced apart from the adjacent stud members by a predetermined angle, and the predetermined angle is 90 degrees in this instance. The piezo-electric element 15 is fixed to a central area of the sensor board 13 as shown in Fig. 3, and is equally spaced from the plurality of stud members 14 in the peripheral area of the sensor board 13. The central area of the sensor board 13 is less affected by the interference between the vibrations propagated through the plurality of stud members 14, and the piezo-electric element 15 can produces an electric signal exactly indicative of the vibrations produced in the pad plate 12a. Further, the electric signal do not vary its level substantially with an identical beating at a different beaten point over the pad member. Because, the difference in the effective length of the propagation path is rather small. Turning back to Fig. 1 of the drawings, the piezo-electric element 15 is connected through wires 17 with a tone generator system 18, and the tone generator system drives a speaker system 19 so as to appropriately produce sounds indicated by the vibrations of the pad plate 12a. The cushion member 16 is shaped in a tubular configuration, and is formed of urethane foam. The cushion member 16 of urethane foam is effective against a noise produced in the case member 11, and isolates the piezo-electric element 15 from the noise. The pad plate 12a, the stud members 14 and the sensor board 13 are fixed in a following manner. First, if the sensor board 13 is formed of acrylonitrile-butadiene-styrene resin, the stud members 14 of acrylonitrile-butadiene-styrene resin are either bolted or bonded to the pad plate 12a, and the sensor board 13 is either bolted or bonded to the stud members 14. On the other hand, the stud members 14 of iron are welded or bolted to the pad plate 12a, and the sensor board 13 of acrylonitrile-butadiene-styrene resin is either bolted or bonded to the stud members 14. If the sensor board 13 is formed of iron, the stud members 14 of acrylonitrile-butadiene-styrene resin are either bonded or bolted to the pad plate 12a as well as to the sensor board 13. The stud members 14 of iron are either welded or bolted to the pad plate as well as the sensor board 12a of iron. In a performance, the player beats the pad member 12, and vibrations are propagated from the beaten point over the pad member 12. The pad member 12 and the case member 11 are isolated from each other by means of the cushion member 16, and the pad member 12 is free from a noise produced in the case member 11, if any. The stud members 14 propagate the vibrations of the pad member 12 to the sensor board 13, and accelerates the sensor board 13. Then, vibrations take place in the sensor board, and the piezo-electric element 15 produces the electric signal from the vibrations. The electric signal is transferred to the tone generator system 18 for electronically synthesizing sound signals, and the sound signals are transferred to the speaker system 19 for producing sounds. Although the vibrations are decayed during the propagation through the stud members 14 and the sensor board 13, the decay is ignoreable rather than the prior art, and the vibrations at a soft beat is large enough to be detectable by the piezo-electric element 15. As a result, any beat is never lost from the sounds produced by the speaker system 19. Moreover, any one of the stud members 14 chatches and transfers the vibrations depending upon the beaten point, and any time delay is never introduced in the propagation. Moreover, the stud members 14 are arranged in such a manner as to allow the sensor board 13 to freely vibrate, and faithfully reproduce the vibrations of the pad plate 12a. Preferred Embodiment Turning to Figs. 4 and 5 of the drawings, an electric percussion instrument embodying the present invention comprises a case member 21, a pad member 22, a sensor board 23, a plurality of damping members 24, a piezo-electric element 25, a cushion member 26 and adhesive sheets 27. In this instance, the sensor board 13 serves as a retainer, and the piezo-electric element 15 serves as a vibration sensor. The case member 21 has a bottom portion 21a and a wall portion 21b merged with the bottom portion 21a, and, accordingly, the case member 21 forms a hollow space 21c therein. The pad member 22 is implemented by a pad plate 22a partially covered with a rubber film 22b. The pad plate 22a is formed of iron, and is 1.0 millimeter in thickness. The rubber film 22b protects an upper surface of the pad plate 22a against strong impacts at beats by a player, and exposes a central area of the back surface of the pad plate 22a. The sensor board 33 is formed of a vibration-transmissive substance selected from the group consisting of iron and acrylonitrile-butadiene-styrene resin. When vibrations of the pad plate 22a are propagated to the sensor board 23, and the sensor board 23 per se well vibrates, and propagates the vibrations to the piezo-electric element 25 without any substantial damping. When the sensor board 33 is formed of acrylonitrile-butadiene-styrene resin, the sensor board 33 is 2.0 millimeters in thickness, and measures 60 millimeters by 60 millimeters. On the other hand, if the sensor board 33 is formed of iron, the thickness is 0.6 millimeter, and the dimensions are equal to that formed of acrylonitrile-butadiene-styrene resin. The damping members 24 are bonded between the exposed area of the pad plate 22a and four corner areas of the sensor board 23 by means of the adhesive sheets 27. The damping members 24 are formed of porous material such as, for example, cellular polyethylene, and each measures 20 millimeters by 20 millimeters. In this instance, the thickness of the damping members 24 is 1.2 millimeters. The damping members 24 thus inserted between the pad plate 22a and the sensor board 23 appropriately damp the vibrations of the pad plate 22a, and causes the vibrations of the sensor board 23 to be fallen into the detectable range of the piezo-electric element 25. For this reason, the damping members 24 are changed to appropriate dimensions depending upon the expected range of impacts, and the thickness of the damping members 24 ranges from 1.0 millimeter to 10 millimeters. If an electric percussion instrument according to the present invention is of a kicked pad, the damping members 24 are changed to be 10 millimeters in thickness, and measure 60 millimeters by 10 millimeters, by way of example. Moreover, the damping members 24 regulates the propagation of the vibrations. When a player beats the pad member 22 at an arbitrary point, the vibrations are diffused from the impact point toward the damping members 24, and a time lug tends to be introduced between an arrival time at one of the damping members 24 and an arrival time at another damping member 24. In general, the time lugs introduce phase differences between the vibrations propagated to the sensor board 23, and undesirably modify the composite vibrations produced in the sensor board 23. However, the damping members 24 take up the time lugs, and faithfully produce the vibrations in the sensor board 23. The piezo-electric element 25 is fixed to a central area of the sensor board 23, and is equally spaced from the plurality of damping members 24 at the corner areas of the sensor board 23. The central area of the sensor board 23 is less affected by the interference between the vibrations propagated through the plurality of damping members 24, and the piezo-electric element 25 can produce an electric signal exactly indicative of the vibrations produced in the pad plate 22a. Though not shown in the drawings, the piezo-electric element 25 is connected through wires 28 with a tone generator system as similar to the one described with respect to Fig. 1, and the tone generator system drives a speaker system so as to produce sounds indicated by the vibrations of the pad plate 12a. The cushion member 26 is shaped in a tubular configuration, and is formed of urethane foam. The cushion member 26 of urethane foam is effective against a noise produced in the case member 21, and isolates the piezo-electric element 25 from the noise. The electric percussion instrument according to the present invention achieves not only the goals of the first embodiment but also appropriately regulates the vibrations of the sensor board to the detectable range of the piezo-electric element 25 by means of the damping members 24. Although particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the scope of the present invention as defined by the appended claims. For example, the vibration sensor may be implemented by any displacement-to-electric signal converter such as, for example, a semiconductor acceleration sensor with a Wheatstone bridge circuit, and the electric percussion instrument according to the present invention may be connected with an amplifier system.

Claims: An electric percussion instrument comprising: a case member (11; 21) vibratory when a force is exerted; a pad member (12; 22) for producing vibrations when a player beats on the electric percussion instrument; a vibration sensor (15; 25) operative to detect vibrations for producing an electric signal indicative of said vibrations; a cushion means (16; 26) provided between said case member (11; 21) and said pad member (12; 22) for isolating said vibration sensor from a noise produced in said case member; a retainer (13/14; 23) supporting said vibration sensor and formed of vibration transmissive substance for propagating said vibrations from said pad member to said vibration sensor; and a damping means (24) connected between said pad member (22) and said retainer (23) for regulating said vibrations of said retainer to a detectable range of said vibration sensor, characterized in that the dimensions of said damping means (24) are changeable depending upon the expected magnitude of impacts exerted on said pad member. The electric percussion instrument as set forth in claim 1, in which said damping means (24) is implemented by a plurality of damping members of a porous material, and said retainer (23) is implemented by a sensor board of the vibration-transmissive substance selected from the group consisting of iron and acrylonitrile-butadiene-styrene resin. The electric percussion instrument as set forth in claim 1, in which said retainer (13/14) comprises a plurality of stud members (14) fixed to said pad member, and a sensor board (13) fixed to said plurality of stud members and supporting said vibration sensor. The electric percussion instrument as set forth in claim 3, in which said plurality of stud members (14) are formed of the vibration-transmissive substance selected from the group consisting of iron and acrylonitrile-butadiene-styrene resin, and said sensor board (13) is formed of the vibration-transmissive substance selected from the group consisting of iron and acrylonitrile-butadiene-styrene resin. The electric percussion instrument as set forth in claim 3, in which said plurality of stud members (14) are angularly spaced apart from each other by a predetermined angle in a peripheral area of said sensor board (13), and said vibration sensor (15) is fixed to a central area of said sensor board (13) radially spaced apart from said plurality of stud members by a predetermined distance.

Inventors: HARADA MINORU, KUROKAWA SYUZO, NOGUCHI YOSHITAKA, HARADA, MINORU, KUROKAWA, SYUZO, NOGUCHI, YOSHITAKA, HARADA, MINORU, C/O YAMAHA CORPORATION, KUROKAWA, SYUZO, C/O YAMAHA CORPORATION, NOGUCHI, YOSHITAKA, C/O YAMAHA CORPORATION
Applicants: YAMAHA CORP, YAMAHA CORPORATION
Application year: 1993
Main classification: G10H3
IPC codes: G10H1, G10H3, G10D13