GB2170639A

GB2170639A - Electronic Percussion Instrument

Info

Publication number: GB2170639A
Application number: GB08502994A
Authority: GB
Inventors: David Simmons
Original assignee: SIMMONS ELECTRONICS Ltd
Current assignee: SIMMONS ELECTRONICS Ltd
Priority date: 1985-02-06
Filing date: 1985-02-06
Publication date: 1986-08-06
Also published as: JPS62501653A; GB8502994D0

Abstract

An electronic percussion instrument comprises a housing 5 provided with a number of electronic transducers 2,3, such as piezoelectric elements, which arrange to provide an electrical signal indicative of not only how hard the instrument is struck, but also indicative of what part of the instrument is struck. The preferred embodiment is an electronic drum comprising a drum pad 1 and a rim 6. Two transducers 2,3 are arranged on the pad so as to provide an indication of where on the pad the drum is struck, as well as how hard the pad is struck, and a further transducer 4 is provided to indicate when and how hard the rim is struck. Signals produced by the transducers can then be utilised by suitable electronic circuitry to produce an electronic sound comparable to that of an acoustic drum. <IMAGE>

Description

SPECIFICATION Electronic percussion instrument The present invention relates generally to an electronic percussion instrument and in particular to an electronic drum.

Electronic percussion instruments have been previously proposed which comprise a relatively rigid (usually wooden) substrate which mounts a single electronic transducer element.

When the housing is struck the resulting shock is transmitted to the transducer element, which produces an electrical signal indicative of the force by which the substrate has been struck. The resulting electrical signal is fed to suitable electronic circuitry which includes means for producing a sound (which may be a drum sound) in accordance with the electrical signal. For example, the electronic circuitry may be arranged to produce a louder sound the harder the substrate is struck.

In a conventional acoustic drum the sound produced depends not only on the force by which the drum is struck but also on what part of the drum is struck e.g. the rim or the skin.

Conventional acoustic drums generally comprise at least one flat playing surface which is surrounded at its periphery by a rim which projects above the playing surface the whole forming a hollow shell. The drum can be struck at a number of positions. It can be struck anywhere on the playing surface between the centre of the playing surface and its periphery, the sound produced by the drum varying according to where the playing surface the drum is struck. Alternatively, the drum can be struck on its rim, in which case a different sound is produced. A further different sound may be obtained by striking both the playing surface and the rim at the same time.

Presently known electronic drums are only able to provide signals indicative of the force by which the drum is struck. An advantage of the present invention is that the electronic instrument also produces signals of a "positional" nature i.e. signals indicative of the position on the instrument of a blow.

Such positional signals can be utilised by associated electronic circuitry to produce a sound which is not only dependent on how hard the instrument is struck, but also on what part of the instrument is struck.

The present invention provides a housing on which are provided a plurality of electronic transducers, said electronic transducers being arranged to produce signals when the instrument is struck which provide an indication of the position on the instrument of the strike.

Preferably said signals produced by said electronic transducers also provide an indication of the force by which the instrument is struck.

Preferably said housing comprises a substrate having two electronic transducers mounted opposite each other towards the periphery of one surface of the substrate. Advantageously the transducers are at equal distances from the centre of the substrate.

Preferably a frame is provided for supporting the substrate, the frame having a rim which surrounds the periphery of the substrate and projects above the surface of the substrate and the frame being provided with a further electronic transducer. A layer of insulating material is preferably interposed between the rim and the periphery of the substrate.

Features and advantages of the present invention will become apparent from the following description of an embodiment thereof by way of example with reference to the accompanying drawings, in which: Figure 1 shows a cross-sectional side view of an embodiment of the present invention as applied in an electronic drum; Figure 2 shows a top plan view of the electronic drum depicted in Fig. 1; and Figure 3 shows in block diagram form a typical example of an electronic circuit which might be used to process the signals produced by the embodiment of the invention depicted in Figs. 1 and 2.

The electronic drum depicted in Figs. 1 and 2 includes a substrate in the form of a hexagonal pad 1 which has mounted on its lower surface two electronic transducers 2 and 3.

The transducers 2 and 3 may, for example, be piezo-electric elements fixed rigidly to the pad. When piezo-electric elements are subjected to shock they deform and produce an electrical signal whose amplitude depends on the amount of deformation to which the piezoelectric element is subjected (i.e. the amplitude of the electrical signal provides an indication of the magnitude of the shock).

The transducers 2 and 3 are arranged diametrically opposite each other towards the periphery of the pad at equal distances from the centre of the pad 1.

When the pad 1 is struck (by a drumstick, for example) the resulting vibration is transmitted to the transducers 2 and 3 which give out respective signals (if they are piezo electric elements) whose amplitudes are indicative of the magnitude of the shock recieved by each respective transducer.

The transducers 2 and 3 on the pad 1 will give out signals of equal amplitude if the pad 1 is struck at a point which is at an equal distance from transducers 2 and 3. However, if the pad 1 is struck at a point which is closer to one transducer than the other the transducer which is closer to the point of strike will give out the signal of greatest amplitude, because it will be subjected to greater shock.

The processing electronics which would be associated with such an electronic drum can therefore use the signals given out by the transducers 2 and 3 to determine where on the pad 1 the drumstick hit. For example, the peak amplitude value of the signal from one transducer could be subtracted from the peak amplitude value of the signal from the other transducer. The resulting signal value would indicate where, between the periphery and the centre of the pad, the pad 1 had been struck.

This "positional" signal can be used to vary such characteristics of the sound produced by the associated electronics as, for example, pitch, timbre, and harmonic content. If desired, the variation in sound characteritic of an acoustic drum can be reproduced.

It should be noted that the amplitude of the signals produced by the respective transducers will depend not only on where the pad 1 is struck but also on how hard the pad is struck.

For example, if the pad is struck hard nearer to transducer 2 than transducer 3 the peak amplitudes of the signals will maintain the same difference relative to each other (the same "positional" information) but the actual peak amplitudes of the signals will be greater than if the pad 1 had only been struck softly in the same spot.

Electronics associated with the drum may, for example, add the two signals produced by the transducers in order to obtain a signal indicative of how hard the pad 1 has been struck. The resulting signal can then be used to vary the sound output by the associated electronics, as in the case with presently known electronic drums. For example, the volume of the sound output could be increased the harder the pad is struck.

The pad 1 is preferably of a material which provides controlled damping of the vibrations occurring when the pad is struck. If the pad 1 is of very rigid material the strength of the shock reaching either transducer 2 or 3 is liable to be similar no matter where the pad 1 is struck. The signals output by the transducers 2 and 3 in this case would be virtually the same and it would therefore be very difficult to extract any positional information from them. It is therefore preferable that the pad is of a material which can provide controlled damping of vibrations, for example an air blown plastics material, such as expanded polypropylene so that any shock is damped in a controlled manner as it travels through the pad.In this case, if the pad 1 is struck over the transducer 2 the magnitude of shock reaching transducer 3 will be significantly less than the magnitude of shock reaching transducer 2.

With reference again to Figs. 1 and 2 the pad 1 is shown supported by a frame 5. The frame 5 has a rim 6 which surrounds the periphery of the pad 1 and projects above the top surface thereof but is insulated therefrom.

Webbing 7 depends from the rim 6 and mounts, in a position generally in line with the centre of the pad 1, a further electronic transducer 4. This electronic transducer 4 may also be a piezo-electric element.

When any part of the frame 5, for example the rim 6, is struck the resulting vibration is transmitted to the transducer 4 via the webbing 7 due to the fact that the frame 5 is of a rigid non-brittle material such as, for example, acetyle resin (Delwyn 100), so that the magnitude of the shock transmitted to the transducer 4 does not greatly depend on what part of the frame 5 is stuck. The transducer 4 will therefore produce a signal which is indicative of how hard the frame 5 is struck. If the transducer 4 is a piezo-electric element the peak value of the amplitude of the signal will be greater the harder the frame 5 is struck.

The signal produced by the transducer may be used to effect the production of a further sound synthesized in electronic circuitry associated with the drum. For example, when the rim 6 of the frame 5 is struck associated electronic circuitry could be arranged to produce a sound which is similar to the sound produced when the rim of an acoustic drum is struck.

The amplitude of the signal produced by the transducer 4 could be arranged to vary a characteristic of the sound, such as the volume of the sound, for example.

It should be noted that the frame 5 is provided with projections 9 which are spaced at intervals around its inner surface. The pad 1 is supported by these projections thus ensuring minimum contact between the frame 5 and the pad 1.

Referring again to Fig. 1, a layer of insulating material 8, is interposed between the rim 6 and the periphery of the pad 1, and may also cover the top surface of the pad 1. The material 8 is preferably of rubber and acts as an insulator and tends to prevent any shock resulting from a blow to the rim 6 from significantly effecting the transducers 2 and 3 on the pad 1. Although a smali amount of shock may be transmitted to the transducers 2 and 3, the magnitude of the shock will not be great. Of course, the insulator 8 will also tend to insulate the frame 5 from any shock resulting from strikes on the pad 1.

In order to cause transducers 2, 3 and 4 to produce any significant signal at the same time when the insulator 8 is provided it will be necessary to strike both the frame 5 and pad 1 at the same time. Any associated electronics may, for example, when all three transducers output a signal at the same time, be arranged to produce a sound similar to that produced by striking simultaneously the rim and playing surface of an acoustic drum.

An example of typical electronic circuit which may be used to process the signals output by transducers 2, 3 and 4 will now be described with reference to Fig. 3.

Electronic sounds are typically produced by digitally sampling an acoustic sound and storing in a memory the resulting digital samples (it should be noted that the it is also possible to utilise analogue techniques, ie voltage controlled oscillators/filters and amplifiers to synthesise the sound. These digital samples can be read out of the memory at a suitable rate, by employing a counter, for example, and be converted into analogue form to produce an analogue signal corresponding to the original acoustic signal by means of suitable analogue processing techniques. This analogue signal can then be applied to a suitable audio circuit in order that a sound similar to the original acoustic sound can be produced. Various characteristics of the synthesized sound can be electronically adjusted prior to audio output.For example, the rate at which the digital samples are read out of the memory can be adjusted by adjusting the counting rate, or the volume of the sound output can be altered, or perhaps an adjustable filter could be included within the electronic circuitry to cut out various frequencies of the sound. It is possibly, therefore, to vary the characteristics of the final sound output by the electronic signal in accordance with one or more control signals input to the electronic circuitry.

Fig. 3 shows digital memories 11 and 12 which may be arranged to contain digital samples of a corresponding acoustic sound.

The analogue signals from transducers 2 and 3 are converted into digital form by analogue to digital converter 13. For example, the peak amplitude values of signals produced by piezoelectric elements could be converted into digital values.

The resulting digital values are applied to arithmetic unit 14, which can be arranged to perform a number of operations on the digital values. The digital values can be substrated to produce a digital value 15 indicative of the position on the pad 1 of the strike. It could also add the signals to produce a digital value 16 indicative of how hard the pad 1 has been struck. These two digital values can be used as control signals to control various characteristics of the electronic sound which is to be produced.

A further signal 17 can be produced by the arithmetic unit 14 when it has finished operating on the signals from the transducers 2 and 3. This signal 17 is applied to a start/stop circuit 18, causing the start/stop circuit 18 to start a counter 19. The counter 19 is arranged to read out the digital samples from the digital memory 11 at a rate determined by a clock, such as a voltage controlled oscillator 20. The samples read out from the digital memory can be reconverted into analogue form by digital to analogue convertor 21, the resulting analogue samples being applied to analogue processing circuit 22 which typically consists of voltage controlled filters and amplifiers in order to reconstruct and enhance a waveform corresponding to the original sound waveform. This sound waveform can then be applied to suitable audio circuitry 23 in order to produce a sound output.

The digital values 15 (positional) and 16 (magnitude) can be used to vary the characteristics of the sound. For example, the digital value 15 could be applied to the VCO 20 in order to vary the counting rate, thus effecting the rate at which the digital sound samples are read from the memory 11. The digital value 16 could be reconverted into analogue form by D/A converter 21, and applied to the analogue processing circuit 22 to effect the volume and harmonic content of the final sound output.

The signal from transducer 4 could be applied to a similar circuit, including a start/stop circuit 24, counter 25, voltage controlled oscillator 26 and digital memory 12, which may store digital samples of a different acoustic sound. No arithmetic unit would be necessary as only one signal is produced by one transducer 4.

The read out from the digital memory 12 can be converted into analogue form by D/A convertor 21, and applied to analogue processing circuit 22. A resulting output sound can then be obtained from audio circuitry 23.

The signal from transducer 4 can be used to start the start/stop circuit 24. It may also be applied directly to the analogue processing circuit 22 in order to effect the output volume of the sound.

It will be appreciated that the electronic circuit described is not the only possible arrangement which could be utilised to process the signals produced by the present invention.

The output signals produced by the instrument of the present invention can be used to control the characteristic of electrically produced sound in any number of ways. For example, the signals from transducers 2 and 3 could be applied to a microprocessor which could determine the position of the strike on the acoustic instrument and choose a different digital memory for each position, from a number of different digital memories storing a number of different sounds.

The signals produced by the present invention can be used to control any number of sound characteristics of an electronically produced sound.

Although the present invention has been specifically described in terms of an electronic drum it will be appreciated that the invention could be utilised in any electronic percussion instrument in which output signals of a positional nature would be advantageous.

It will also be appreciated that more than two electronic transducers may be arranged at various positions on a single housing.

Claims

1. An electronic percussion instrument comprising a housing which is provided with a pluraiity of electronic transducers arranged to produce signals when the instrument is struck which are indicative of the position on the instrument of the strike.

2. An electronic percussion instrument in accordance with claim 1, wherein said housing comprises a substrate provided with two electronic transducers mounted opposite each other towards the periphery of the substrate.

3. An electronic percussion instrument in accordance with claim 2, wherein said substrate is of material which provides controlled damping to any vibrations to which the substrate is subjected.

4. An electronic percussion instrument in accordance with claim 3, wherein said material is expanded polypropylene.

5. An electronic percussion instrument in accordance with any one of the preceding claims, wherein said housing further comprises a frame member which forms a ring around the periphery of a planar substrate and projects above the surface thereof.

6. An electronic percussion instrument according to claim 6, wherein the frame member is provided with a transducer.

7. An electronic percussion instrument in accordance with claim 5 or 6, wherein a number of spaced projections are provided on the internal surface of the rim, whereby to provide support for the substrate.

8. An electronic percussion instrument in accordance with claim 5, 6 or 7, wherein said frame member is of a relatively rigid material.

9. An electronic percussion instrument in accordance with any of claims 5 to 8, wherein a layer of insulating material is interposed between points of contact of the frame member and the substrate, whereby to reduce the transmission of vibrations between the substrate and the frame member.

10. An electronic percussion instrument in accordance with claim 11, wherein said insulating material is rubber and constitutes a playing surface over the substrate.