Touch-responsive Tone Envelope Control Circuit For Electronic Musical Instruments

Abstract

In a keying system for an electronic musical instrument in which an individual keyer is operative by the actuation of a corresponding playing key but a keyed tone signal has a predetermined amplitude irresponsive to a key depression intensity, there is provided in combination with the keyer a corresponding circuit means producing a tone signal of an envelope pattern or abrupt buildup and subsequent decay, a so-called attack signal, in response to the key depression intensity. The touch-responsive attack signal gives forth an effective touch-responsive auditory sensation of the total sound.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a touch-responsive tone envelope control circuit for electronic musical instruments, and more particularly, to a specific tone envelope control circuit which can improve the tone envelope effects in a key-operated electronic musical instruments such as an electronic organ to provide excellent effects of music being played.

SUMMARY OF THE INVENTION

The principal object of the present invention is to provide a touch-responsive tone envelope control circuit for use with an electronic musical instrument which easily permits the instrument incorporating the circuit therein to provide a tone signal having an envelope pattern of abrupt buildup with a subsequent decay, a so-called attack signal, in superposed relation with a keyed tone signal of a predetermined amplitude irresponsive to a key depression intensity.

Another object of the present invention is to provide the touch-responsive tone envelope control circuit which is simple in construction, easy and inexpensive to manufacture, and reliable in operation.

A further object of the present invention is to provide the touch-responsive tone envelope control circuit including a plurality of gate circuits each gating a supplied corresponding tone signal to be keyed in response to the intensity of depression of a corresponding playing key.

A still further object of the present invention is to provide the touch-responsive tone envelope control circuit in which said gate circuit is adapted to gate a tone signal having a footage different from that of a tone signal being applied to the corresponding keyer circuit.

Other object, features and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram showing an embodiment of the present invention by one unit.

FIG. 2 is a circuit diagram showing another embodiment of the present invention by one unit.

FIGS. 3 to 5 are diagrams for explaining the operations and functions of circuits according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, same characters and references indicate same parts hereunder.

Reference will be made to a touch-responsive tone envelope control circuit of the embodiment according to the present invention with reference to FIG. 1, in which a circuit associated with only one key is shown for simplicity of illustration. T.sub.1 designates an input terminal of a keyer circuit S, to which a tone signal generated by a corresponding tone source circuit which is easily available is applied. The keyer circuit S is so arranged to be keyed in association with the depression of a corresponding playing key K arranged on a keyboard of an electronic musical instrument, and to apply its output at a tone signal output terminal T.sub.o. L designates a coil grounded at one end adapted to vary the interlinking fluxes in association with depression of the above-mentioned key K, of which the other end l is connected through a series circuit of a rectifying element D and a resistor R to the gate of a field effect transistor Q (hereunder referred to by FET), while a connection point d between the element D and the resistor R is grounded via a parallel circuit of a capacitor C.sub.1 and a resistor R.sub.1. The output terminal T.sub.o is connected to the drain of the FET Q. The drain electrode is connected through a resistor R.sub.2 to a power source +Vcc. The source of the FET Q is grounded through a series circuit of a resistor R.sub.3 and a variable resistor R.sub.4 in turn, of which the connection point r is connected through resistors R.sub.6 and R.sub.5 to the power source +Vcc and the input terminal T.sub.1, respectively.

The usual keyer circuit S is adapted to be keyed only upon depression of the key K. By means of the resistors R.sub.4 and R.sub.6 the gate to source voltage of the FET Q is determined at a required value. Thus, the FET Q is changed to its nonconducting state when the gate potential of the FET Q is at earth potential or zero potential. Further, the number of the above-mentioned circuit arrangement shown in FIG. 1 which is installed in the console of the instrument corresponds in number to the playing keys, for example, 61.

Now, the operation of the circuit as mentioned above will be described hereunder.

When any one key K arranged in the electronic musical instrument is depressed by the player, the normal keyer circuit S is operative presenting a predetermined internal impedance to transmit a tone signal applied at the input terminal T.sub.1 to the output terminal T.sub.0 as a normal keyed tone signal B.sub.s (as shown in FIG. 5) having a predetermined level irresponsive to the key depression intensity. At this time, a magnetic member (magnetized) attached to the key moves close to or away from a fixed coil L, thereby resulting in a damped alternating current voltage approximately proportional to the intensity or speed of depression of a playing key due to a variation in interlinking fluxes established round the coil, the waveform of which is shown in FIG. 3. Theoretically this voltage should be a DC impulse, but actually it becomes of the above-shown waveform due to mechanical bouncing of the key and the associated elements. The induced alternating current voltage is positively rectified by the element D and then the resulting positive DC impulse voltage is applied to the parallel circuit of the capacitor C.sub.1 and the resistor R.sub.1 one end thereof being grounded. At the parallel circuit the waveform of the DC impulse voltage is translated into an approximate sawtooth pulse signal having a magnitude according to the key depression intensity as shown in FIG. 4 and the resulting pulse signal is applied to the gate of the FET Q and as a result, the FET Q is made in its conducting state for a short period of time for example, 0.1 to 0.5 second immediately after the key depression, so that the input tone signal having been applied to the source of the FET Q may be derived as a tone signal having an envelope of an abrupt buildup and a subsequent decay or an attack signal immediately after the key depression. Thus, at the output terminal T.sub.o may be derived an output tone signal in which the attack sound signal A.sub.s in response to the key depression intensity is partially superposed on the normal keyed tone signal B.sub.s of a predetermined amplitude irresponsive to the key depression intensity as shown in FIG. 5. In other words, the normal keyed tone signal additively providing the attack sound signal A.sub.s may be derived at the output terminal T.sub.o.

Now, the amplitude characteristics of the attack sound signal A.sub.s may be varied in accordance with the magnitude of a key depression speed as shown by several dotted curves in FIG. 5 in the various manners. The variation in the amplitude of the attack sound signal substantially provides the same auditory effect as the amplitude of a tone output of the instrument is wholly varied to the audience of music being played. Thus, at the output terminal T.sub.o an output tone signal having an amplitude substantially corresponding to the key depression intensity or speed may be derived. However, when the key K is depressed quite slowly, the coil L does not induce any electromotive force or voltage, so that the FET Q is kept in its nonconducting state and of course, no attack sound signal A.sub.s is produced.

If the playing key is kept depressed, no further voltage is induced in the coil L. Accordingly, the gate potential of the FET Q becomes at ground potential after a required short period of time from the key depression and hence, the FET Q is rendered to be in its nonconducting state. Then, at the output terminal T.sub.o there can be continuously derived only the normal keyed tone signal B.sub.s of a predetermined amplitude, which is shown by a flat curve in FIG. 5, from the keyer circuit S being keyed by retaining the key depression, still release of the depressed key as shown in FIG. 5.

Upon release of the key being depressed, the key is made restored by its self-return action and simultaneously, the keyer circuit S is made open to be in its nonconducting state, so that no output signal is developed at the terminal T.sub.o.

As described above, in the circuit arrangement, not only the amplitude characteristic of an output tone signal of the instrument can be relatively varied substantially only by varying the amplitude of an attack signal in accordance with the key depression intensity, but also the buildup amplitude of the tone signal can be made more distinct to permit more advantageous playing of the instrument and to easily provide a so-called touch-responsive effect resembling that of a piano.

Now, in the circuit arrangement, a conventional tone color circuit J may be inserted between the drain of the FET Q and the output terminal T.sub.o as shown by a dotted line block in FIG. 1. For example, if the tone color circuit is adapted to emphasize the high harmonics of the tone signal its buildup amplitude characteristic or the starting of the gated tone signal becomes more distinct and as a whole the tone color of the output signal can be varied with the decay of the attack sound, thus providing interesting effects of music being played.

As a substitution of the coil L, magnetosensitive elements or pressure-sensitive electric elements may be used. Further, the FET used here may be substituted by other switching element such as a transistor of other types, diodes or vacuum tube etc.

Referring to FIG. 2, there is shown another embodiment of the present invention. However, the arrangement is the same as that of FIG. 1 except that the connection point r is connected via the resistor R.sub.5 to another input terminal T.sub.2 to which another tone signal having a different footage number is applied from a different tone source circuit which is available and is not shown here, in place of the terminal T.sub.1. In this case it will be understood that the instrument using the circuit provides a normal keyed tone signal having an attack sound signal A.sub.s of which the amplitude is varied in accordance with the intensity of depression of a corresponding playing key and of which the footage number (e.g., 4') is different from that of a tone signal (e.g., 8') applied to the keyer circuit. Further, to the terminals T.sub.1 and T.sub.2 tone signals having a same footage number and different tone colors (or waveforms) may also be applied. The operation and function and effect of the circuit according to the second embodiment should be understood in the same manner as in the first embodiment and therefore, the details thereof have been omitted.

Claims

I claim:

1. A touch-responsive keying system for an electronic musical instrument having a plurality of keys and a tone generator, said system comprising:

a like plurality of voltage generating means, each being responsive to the intensity of depression of a corresponding one of said plurality of keys for generating a voltage also responsive to the intensity of depression of said corresponding key,

a like plurality of keyer circuit means connected to said tone generator, each keyer circuit means being capable of producing a keyed tone signal having a predetermined amplitude irresponsive to the depression intensity of a corresponding playing key, and

a like plurality of gate circuit means, each being connected to a respectively corresponding voltage generating means, to said tone generator and to a respectively corresponding keyer circuit means, each of said gate circuit means being responsive to the level of said generated voltage from the respectively corresponding one of said voltage generating means for developing a tone signal having an envelope pattern of abrupt buildup and subsequent decay and which key depression intensity responsive tone signal output is connected to combine with the predetermined amplitude output of the respectively corresponding keyer circuit for the each of said plurality of keys.

2. A touch-responsive keying system according to claim 1, in which the input of each of the gate circuit means is connected to the input of the respectively corresponding keyer circuit.

3. A touch-responsive keying system according to claim 1, in which the input of each of the gate circuit means is connected to a tone source generating a tone signal having a waveform different from that connected to the input of the respectively corresponding keyer circuit means.

4. A touch-responsive keying system according to claim 1, in which each of said gate circuit means includes an active element having a control electrode and first and second electrodes, said control electrode being connected to an output terminal of the respectively corresponding voltage generating means, said first electrode being connected to a tone source which is also connected to the input of the respectively corresponding keyer circuit means and said second electrode being connected to the output of said keyer circuit means.

5. A touch-responsive keying system according to claim 4, in which said active element is a field-effect transistor.

6. A touch-responsive keying system according to claim 1, in which each of said voltage generating means includes a coil adapted to generate a damped AC voltage responsive to the actuation speed of a respectively corresponding playing key, a unidirectional conducting element for rectifying the AC voltage, and a circuit for translating the rectified voltage into a pulse signal of an approximate sawtooth waveform.

7. A touch-responsive keying system as in claim 1 in which each of said gate circuit means includes an active element having a control electrode and first and second electrodes, said control electrode being connected to an output terminal of the respectively corresponding voltage generating means, said first electrode being connected to a first tone source having a first footage, the input of the respectively corresponding keyer circuit means being connected to a second tone source having a second footage, and said second electrode being connected to the output of said keyer circuit means.

8. In an electronic musical instrument having playing keys and tone sources, a touch-responsive keying system for each of said playing keys, said system comprising:

an input terminal connected to a predetermined one of said tone sources.

an output terminal,

a keyer circuit means connected to said input terminal and said output terminal for keying a tone signal from said tone source to said output terminal with a predetermined amplitude irresponsive to the depression intensity of said key;

voltage generating means for generating a voltage responsive to the depression intensity of said key; and

a gate circuit means connected to said voltage generating means, to at least one of said tone sources and to said output terminal for developing a tone signal having an envelope pattern of an abrupt buildup and a subsequent decay with an amplitude determined by said voltage.

9. A touch-responsive keying system according to claim 8 in which said gate circuit means has a tone signal input connected to said input terminal for receiving a tone signal from said predetermined tone source in common with the input of said keyer circuit means.

10. A touch-responsive keying system according to claim 9 in which said gate circuit includes a field-effect transistor having a gate electrode, a source electrode and a drain electrode, said gate electrode being connected to said voltage generating means, said source electrode being connected to said input terminal and said drain electrode being connected to said output terminal.

11. A touch-responsive keying system according to claim 9 in which there is further provided a tone color circuit for emphasizing high harmonics of the tone signal, said tone color circuit being connected between said gate circuit means and said output terminal.

12. A touch-responsive keying system according to claim 8 in which there is further provided a second input terminal connected to a tone signal input of said gate circuit means which second input terminal is connected to a different one of said tone sources.

13. A touch-responsive keying system according to claim 12 in which there is further provided a tone color circuit for emphasizing high harmonics of the tone signal, said tone color circuit being connected between said gate circuit means and said output terminal.

14. A touch-responsive keying system according to claim 12 in which said gate circuit means includes a field-effect transistor having a gate electrode, a source electrode and a drain electrode, said gate electrode being connected to said voltage generating means, said source electrode being connected to said second input terminal and said drain electrode being connected to said output terminal.

15. A touch-responsive keying system according to claim 8 in which said voltage generating means includes a coil adapted to generate a damped AC voltage responsive to the depression speed of said key, a unidirectional conducting element for rectifying said AC voltage, and a circuit for translating the rectified voltage into a pulse signal of an approximate sawtooth waveform.