EP0215018A1

EP0215018A1 - A pickup arrangement for an electronic percussion instrument

Info

Publication number: EP0215018A1
Application number: EP19860901105
Authority: EP
Inventors: David Simmons
Original assignee: SIMMONS ELECTRONICS Ltd
Current assignee: SIMMONS ELECTRONICS Ltd
Priority date: 1985-02-06
Filing date: 1986-02-06
Publication date: 1987-03-25
Also published as: WO1986004718A1

Abstract

Agencement de capteur pour un instrument électrique à percussion utilisant un boîtier pourvu d'un certain nombre de transducteurs électroniques disposés de manière à produire un signal électrique indiquant non seulement la force avec laquelle on frappe l'instrument, mais également l'endroit où l'instrument est frappé. Le mode préféré de réalisation est un tambour électronique comprenant une membrane de tambour (1) et un bord (6). Des transducteurs (2, 3) sont disposés sur la membrane (1) de manière à fournir une indication de l'endroit où la membrane (1) est frappée, ainsi que de la force avec laquelle la membrane (1) est frappée. Un autre transducteur (4) indique quand le bord (6) est frappé et avec quelle force. Les signaux produits par les transducteurs peuvent être utilisés par des circuits électroniques appropriés pour produire une sonorité électronique comparable à celle d'un tambour acoustique.Sensor arrangement for an electric percussion instrument using a housing provided with a number of electronic transducers arranged so as to produce an electrical signal indicating not only the force with which the instrument is struck, but also where the instrument is struck instrument is struck. The preferred embodiment is an electronic drum comprising a drum membrane (1) and an edge (6). Transducers (2, 3) are arranged on the membrane (1) so as to provide an indication of where the membrane (1) is struck, as well as the force with which the membrane (1) is struck. Another transducer (4) indicates when the edge (6) is struck and with what force. The signals produced by the transducers can be used by appropriate electronic circuits to produce an electronic sound comparable to that of an acoustic drum.

Description

A Pickup Arrangement for an Electronic Percussion Instrument

The present invention relates to a pickup arrangement for an electronic percussion instrument, and more particularly, but not exclusively, to a pickup arrangement for an electronic drum. Pickup arrangements for electronic drums have been previously proposed, such as pickup arrangements which comprise a relatively rigid (usually wooden) substrate which mounts a single electronic transducer element.When the substrate is struck (eg by a drumstick) the resulting shock is transmitted to the transducer element, which produces an electrical signal which varies in accordance with the force by which the substrate has been struck. The resulting electrical signal is fed from the pickup arrangement to suitable electronic circuitry which includes means for processing the signal in order to produce a sound there¬ from (which may be a drum sound) , characteristics of the produced sound may be arranged to be effected by variation in the signal from the pickup arrangement. For example, the electronic circuitry may be arranged to produce a louder sound the harder the substrate is struck.

A problem with such a pickup arrangement is that the only information which can be derived from the produced signal is information on how hard the pickup arrangement has been struck (ie "dynamic" information). Although this signal could possibly be used in associated electronic circuitry to vary several characteristics of the produced sound, the variation of the signal depends only on the force with which the pickup is struck and the signal is not effected by where on the pickup is struck. On the other hand, in a conventional acoustic drum the sound produced by striking the drum varies not only in accordance with how hard the drum is struck but also in accordance with what part of the drum is struck. 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 any¬ where on the playing surface between the centre of the playing surface and its periphery, the sound produced by the drum varying according to where on the playing surface the drum is struck notwithstanding any variation in the force by which 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_..

As stated above, presently known pickups for electronic drums are only able to provide signals from which dynamic information can be derived. The produced signal does not vary depending on where the pickup is struck. An advantage of the present invention is that signals are produced by a pickup arrangement from which not only dynamic information can be derived, but also positioned information ie where the pickup has been struck. The present invention provides a pickup arrangement for an electronic percussion instrument compris¬ ing a housing provided with a plurality of ^"electronic transducers, the transducer being arranged to produce electrical signals when the housing is struck, from which signals information can be derived relating to with what force the housing has been struck and information relat- ing to the position of the strike on the housing.

Preferably the housing comprises a substrate which mounts a plurality of electronic transducers of like-type, signals produced by the electronic transducers being operable on to derive dynamic and positional information therefrom.

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 at least one further electronic transducer. A layer of insulating material is preferably interposed between the rim and the periphery of the substrate.

Advantageously the signal given out by the frame transducer when the frame is struck can be utilised by associated electronic circuitry to effect the character¬ istics of a further sound produced by the electronic circuitry, the further sound being unrelated to the sound produced by striking the substrate. If both the substrate and frame are struck at the same time so that transducers on the substrate and frame give out signals at the same time, these signals may be utilised to effect the production of yet a further unrelated electronic sound. I this way similar effects can be produced as those given by a conventional acoustic drum, as discussed above.

In a conventional acoustic drum, when the drum surface is struck there is a large movement of the drum skin. This "feel" effect of an acoustic drum is not re¬ produced in prior art pickup arrangements for electronic drums.

Also, in the case of the present invention, where the pickup arrangement is provided with a frame for support- ing the substrate there is a possibility that when the substrate is struck some of the shock of the strike may also be transmitted to the frame, effecting the frame transducer. Whilst this "cross-talk" effect may be desirable in some cases in order to effect the production of certain sound effects by associated electronic circuitry, in other cases it may not be so desirable.

The present invention therefore also envisages, where the pickup arrangement includes a substrate supported by a frame, mounting the substrate resiliently with respect to the frame.

Mounting the substrate in such a manner has the effect of reducing cross-talk between transducers on the frame and transducers on the substrate, as well as giving a realistic "feel" to the pickup arrangement when it is struck.

Features and advantages of the present invention will become apparent from the following descriptions of embodiments thereof with reference to the accompanying drawings, in which: Figure 1 shows a cross-sectional side view of a first embodiment of a pickup arrangement in accordance with the present invention;

Figure 2 shows a top plan view of the pickup arrangement of Figure 1; Figure 3 shows a cross-sectional side view of a further embodiment of a pickup arrangement in accordance with the present invention;

Figure 4 shows a top plan view of the pickup arrangement of Figure 3_? showing in outline a transducer arrangement of the pickup;

Figure 5 shows an exploded plan view of the transducer arrangement of the embodiment of Figures 3 and ;

Figure 6 shows a cross-sectional side view of a further embodiment of the present invention, illustrating a different support structure for the substrate;

Figure 7 shows a cross-sectional side view of yet a further embodiment of the present invention, illustrating yet another support structure for the substrate, and

Figure 8 shows a schematic block diagram of a typical electronic circuitry arrangement which may be used to produce electronic sounds in accordance with the signals produced by the embodiment of Figures 1 and 2. A first embodiment of the present invention will now be described with reference to Figures 1 and 2. The pickup arrangement depicted in Figures 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 piezo-electric element is subjected (ie the amplitude of the electrical signal provides an indication of the magnitude of the shock).

The transducers 2 and 3 are arranged diametric¬ ally 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 received by each respective transducer.

The transducers 2 and 3 on the pa.d 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 signals given out by transducers 2 and 3 are therefore effected not only by how hard the pad 1 is struck, but also depend on the position of the strike on the pad 1. Processing electronics associated with the pickup arrangement can therefore utilise the signals given out by transducers 2 and 3 to provide not only inform- ation on how hard the pad 1 has been struck ("dynamic" information) but also the position of the strike on the pad 1 ("positional" information). This information can then be utilised to vary the sound produced by the associated electronics, so that the sound produced depends on the position on the drum of the strike as well as on the force by which the drum is struck.

For example, in order to obtain the positional information from the signals produced by transducers 2 and 3 the associated electronic circuitry may be arranged to subtract the peak amplitude value of the signal produced by one transducer from the peak amplitude value of the signal produced by the other transducer. The resultant signal would be directly related to where the pad had been struck between the two transducers 1 and 2 e if the subtraction result is zero the pad 1 has been struck at a point equidistant from both transducers. If the result is greater than zero the pad 1 has been struck nearer one transducer than the other. The resultant signal could then be used to effect the sound produced by associated electronic circuitry, in sound production which depends on the position of the strike on the pad 1. For example, the positional information derived from the signals produced by the two transducers can be used to vary such characteristics of the sound produced by associated electronic circuitry as, for example, pitch, timbre, and harmonic contents. If desired the variation in sound in accordance with position of strike which is characteristic of an acoustic drum could be reproduced ie the further the pickup is struck from the centre towards one transducer the more of a sound akin to the sound produced by striking the periphery of the surface of an acoustic drum could be reproduced.

To derive the dynamic information from the signals produced by transducers 1 and 2 the signals can be added. The result of the addition will indicate how hard the pad has been hit (the greater the sum the harder the pad has been hit).

The dynamic information can also be used to vary the characteristics of sound output by electronics associated with the drum. For example, the volume of the sound output could be increased the harder the pad is struck.

It will be noted that if the pad 1 is struck at a point A inbetween transducers 2 and 3, similar positional information will be derivable to that derivable when the drum is struck at point B ie although point B is at the periphery of the pad 1 the positional information derivable from a strike thereon will be the same as that derivable from a strike in the centre of the pad 1. In order to reduce the likelyhood of this phenomenon causing any disadvantages as far as the production of realistic sould effects is concerned the pickup may be orientated in a particular manner with res¬ pect to the drummer when the drum kit is set up. For example, a particular drummer may have a tendency to hit a particular part of an acoustic drum when he desires a particular sound effect. For example, when the drummer wished to strike the periphery of the drum surface to gain the particular sound given out by striking there, he may tend to strike the periphery at a point left or right of the centre of the drum with respect to an axis passing across the drumm parallel with the eye-line of the drummer, rather than striking the periphery above or below this axis. By setting up the pickup of figures 1 and 2 with respect to the drummer such that his eye line is parallel with the line x-x connecting transducers 2 and 3 , he will tend to strike the periphery of the pad 1 at a position proximate to one or other of the transducers rather than at a position near point A.

The production of realistic sound effects may thus be assured by taking care to orientate the pickup correctly with respect to the drummer.

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 (ie absorbed) 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 Figures .1 and 2 the pad 1 is shown supported by a frame 5 - The fram 5 has a rim ό 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 fram 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 struck. The transducer 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. Variation in the signal produced by the transducer 4 (eg variation in the amplitude of the signal) 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 Figure 1, a layer of insulat¬ ing 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 small 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 all of transducers 2,3 and 4 to produce signals, frame 5 and pad 1 can be struck simultaneously

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.

For example, circuitry could be arranged to detect when all the transducers produce a signal at the same time and be arranged to- produce a particular sound when this occurs. The sound could "be varied in accordance with, for example, the strengths or relative strengths of the signals produced.

At least one F.S.R. is utilised in the transducer arrangement 30, which is arranged to produce signals from which can be derived both positional and dynamic information.

Figure 4 shows, in ghost outline, the position of the arrangement 30 with respect to the periphery of the pad 1. The insulating layer 8 is provided over the surface of the pad 1 and transducer arrangement 30 , in a similar manner to the first embodiment.

The transducer arrangment 30 can best be described with reference to Figure 5 _> which shows the arrangement 30 in exploded form, and also illustrates the circuit connections which would be made thereto in operation. In the embodiment illustrated the transducer arrangement 30 comprises a "sandwhich" arrangement consisting of, from the bottom upwards, a plastic layer 31 on which is printed a conductive layer (not shown, as it is hidden under a force sensing resistive layer 32), a force sensing resistor layer 3 printed over- the conductive layer 31 • a resistive sheet layer which in the pickup arrangement is over the force sensing resistive layer 32 in contact therewith, but is shown separately in Figure 5 for the sake of convenience, and a further plastic layer 34« The resistive sheet 33 has a resistive gradient across the diameter thereof, as represented by^¬ line 35 -

In operation, circuit connections would be made to the transducer arrangement 30 as illustrated in Figure 5»

The signal from which dynamic information is derivable (the "dynamic signal") is taken from point 36 between resistor 37 and the conductive layer. The resistor 37 is connected in operation to a voltage source V. When the pad 1 of the pickup arrangement is struck, the resistance of the F.S.R. 3 immediately drops to its working range, and the resistance value within the working range depends on the force by which the pad 1 is struck. The signal voltage at point 36 will thus vary in accordance with how hard the pad 1 is struck, as this effects the value of the resistance of the F.S.R. 32. A dynamic signal is thus produced at point 36.

The signal from which positional information is derivable (the "positional signal") is taken from point

38 on the perimeter of the resistive sheet layer 33• The resistance in the "circuit between earth and the point at which the pad 1 is struck will vary depending where the pad 1 as struck, as the circuit is connected to earth at point 39 at the periphery of resistive sheet layer 33, and the resistive sheet layer 33 has a resistive gradient 35 across its diameter. The signal value taken from 38 therefore will therefore vary depending where on the pad 1 the pad 1 is struck, to give a positional signal. For example if the pad 1 is struck adjacent point 39 the positional signal will be zero, as point 39 is tied to earth. If the pad 1 is struck at a point adjacent 38 on the other hand, the posit onal signal will be at its maximum value, as the maximum resistance of the sheet layer 33 exists between point 38 and earth. Any strike along the line connecting points 38 and 39 will produce positional information which varies in accordance with the position of strike along the line.

It will be noted that this embodiment performs in a similar manner with respect to positional information as the embodiment of Figures 1 and 2, in that a strike at point C will produce the same positional information as a strike at point D (of strikes at points A and B in the first embodiment). The production of realistic sound effects may be assured in a similar manner to the first embodiment by orientating the pickup arrangement suitably with respect to the drummer.

It will also be noted that the variable resist¬ ance according to position of strike forms part of the same circuit from which the dynamic signal is taken. In order to ensure that the variation in resistance across the resistive layer 33 does not induly effect the dynamic signal, and vice versa with respect to the value of resistance of the F.S.R. and the positional signal, values of resistance are advantageously chosen such that the resistnace of the force sensitive resistor layer 3 in its working range is much greater than the resistance of the sheet 33 across its diameter. Typical resistor values would be resistor 37 10KΛ, F.S.R. 32 (working range) 50 Kιt , and resistive sheet (across the whole diameter) 4 KΛ Any error remaining can, at any rate, be removed by suitable processing electronics (which is known to those skilled in the art) which would operate on the "raw" positional and dynamic signals to produce derived positional and dynamic information. it should be noted that it- is it wished to increase the value of the F.S.R. it is possible to use two F.S.R. 's "back to back" in the arrangement .

Dynamic and positional information derived from this embodiment of the pickup in accordance with the present invention can be used by vary the characteristics of sound produced electronically, as for the 'first embodiment. it will also be noted that this embodiment is also provided with a frame member 5 which has a transducer

4-

In both the embodiments described above the pad 1 has been shown being .supported by projections 9 extend¬ ing from the frame 5- This arrangement is satisfactory for most application, but does not tend to reproduce the large movement of an acoustic drum skin (ie the "feel"). Also, particularly in the case of the first embodiment it is possible that too much "cross-talk" may occur between transducers on the frame and transducers on the pad ie when the pad is struck there may also be some shock transmitted via the pad 1 and frame 5 to the frame transducer 4> Although in some applications such cross¬ talk may be derivaole eg in order that sound effects relat¬ ing to the cross-talk may be produced, a great deal of cross-talk may be undesirable.

The following description, relating to Figures 6 and 7 of the drawings, describes embodiments of the present invention relating to a pickup arrangement (in particular relating to the first embodiment described, although they may be used with the second embodiment) showing different structures for supporting the pad 1. These arrangements have the advantage that they, result in a reduction of cross-talk between the transducers on the pad and transducers on the frame, as well as provid- ing the "feel" typical of the large movement of the drum surface occuring when a conventional drum is struck .

The same reference numerals are used for the following embodiment for elements which have been described in relation to the previous embodiments. The figures show a pickup arrngement for an electronic percussion instrument comprising a frame member 5 and a pad 1. Electronic transducers 2,3,4 are mounted on the pad 1 and frame member 5 respectively. The upper surface of the pad 1 is covered by a layer of insulating material 8. The pad 1 is resiliently mounted with respect to the frame member 5«

In the -embodiment of Figure 6 the pad 1 is resiliently supported oγ being secured to the underside of the layer of insulating material 8. In the preferred embodiment the pad is of hexagonal shape in plan as is the shape of the resilient insulating material 8. However, the pad 1 is of lesser area in plan than the area of the material 8 to leave a peripheral margin around the pad 1. In order to maintain the shape of the insulating material 8 about the pad 1 and in the frame, a peripheral frame la is provided in a shaped recess formed in the peripheral margin of the material 8. As before the frame member 5 is provided with projections 9 which support combination of pad 1 and insulating material 8. The pad 1 and frame la are separated by a gap 50 . therefore, the only contact the pad 1 has with the frame member 5 is via the insulating material 8. Any cross-talk between transducers 2 and is therefore reduced with respect to the case where pad-1 and peripheral ring la are continuous. The insulating material 8 is preferably rubber. In Figure 7 the pad 1 and peripheral ring la are shown mounted on a cushion of resilient material 1 _> such as low density foam. The only contact between transducers 2, 3 and transducer 4 is via the insulating material 5 or via the cushion 51_? resulting in reduced cross-talk. It should be noted that in this embodiment the gap 5 is not particularly necessary in order that cross-talk be reduced. The pad 1 could be extended as is the case with the previous embodiments ie the frame la could be omitted.

The pickup arrangements in accordance with these embodiments has the further advantage that a real¬ istic "feel" is provided by mounting the pad resiliently with respect to the frames ie when the pad is mounted resiliently the whole of the pad is allowed to move when it is struck. The movement of the pad mimics the large movement of an acoustic drum skin.

It will be appreciated that the present invention is concerned only with a pickup arrangement for an electronic percussion instrument, and is not concerned with any of the electronic processing equipment which would be associated with the pickup arrangement when it is desired to operate the pickup so as to produce electronic sound. The pickup arrangement of the present invention is arranged to produce signals from which positional and dynamic information can be derived. it is within the knowledge of the person skilled in the art to design suitable electronic circuitry to utilise these signals to vary the character- istics of an electronically produced sound.

However, for the sake of completion, the follow- ing is a very generalised description of an example of electronic circuitry which could be used in conjunction with signals produced by the pickup arrangements of Figures 1 and 2, with reference to Figure 8. It will be appreciated that Figure 8 is only a schematic block diagram and that a person skilled in the art would be able to choose suitable components to form the circuit illustrated generally in Figure 8. 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 amplifies to synthesise the sound). These digital samples can be read out of the memory at a suitable rage by employing a counter, for example, and be convert¬ ed 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 ouput 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. Figure 8 whows digital memories 11 and 12 which may be arranged to contain digital samples of a correspond ing acoustic sound. the analogue signals from transducers 2 and 3 of the first embodiment are converted into digital form by analogue to digital convertor 13. For example, the peak amplitude values of signals produced by piezo-electric 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 subtracted 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 lό 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 αut 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 ouput.

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 VCC 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 convertor 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 pickup 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 the various transducers employed 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 in the embodiment of Figures 1 and 2 more than two electronic transducers may be arranged at various positions on the pad 1. For example, 3 transducers may be arranged at the respective comers of an equilateral triangle, each transducer being equidistant from the centre of the pad 1 It should be noted that the shape of the pad 1 need not be hexagonal as described but could be any other convenient shape.

Claims

C aims

A pickup arrangement for an electronic percussion instrument comprising a housing provided with a plurality of electronic transducers, the transducers being arranged to produce electrical signals when the housing is struck, from which signals information can be derived relating to the force with which the housing has been struck and information relating to the position of the strike on the housing. 0

2. A pickup arrangement in accordance with claim 1, wherein said plurality of electronic transducers are all transducers of the same particular type.

5 3» A pickup arrangement in accordance with claims 1 or 2 wherein said housing comprises a substrate provided with a plurality of electronic transducers arranged towards the periphery substrate equidistant from the centre of the substrate. 0

4> A pickup arrangement in accordance with any claim 3 wherein there are two transducers arranged opposite to each other.

5 5• A pickup arrangement in accordance with any preceding claim wherein said substrate is of material which provides controlled damping to any vibrations to which the substrate is subjected.

C 6. A pickup arrangement in accordance with claim 5, wherein Setid material is expanded polypropylene.

7« A pickup arrangement in accordance with claim

1 or 2, wherein said electronic transducers include at 5 least one force sensitive resistor mounted in contact with a resistive sheet layer.

0ΛK3H^AL δ. A pickup arrangement 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.

9. A pickup arrangement according to claim 8, wherein the frame member is provided with a transducer.

_j0 10. A pickup arrangement in accordance with claims 8 or , wherein said frame member is of a relatively rigid material.

11. A pickup arrangement in accordance with any 15 of claims 8 to 10, 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.

' 20 .

12. A pickup arrangement in accordance with claim 11, wherein said insulating material is rubber and constitutes a playing surface over the substrate.

25 13_* A pickup arrangement in acco.- ance with any of claims 8 to 12, wherein a number of spaced projections are provided on the internal surface of the rim, whereby to provide support for the substrate.

30

14• A pickup arrangement in accordance with any of claims 8 to 12, wherein the substrate is resiliently mounted with respect to the frame.