Electronic Musical Instrument With Key And Pedal-operated Volume Controls

Abstract

An electronic musical instrument comprises a first performance section which produces music signals by manipulation of keys in a keyboard at predetermined levels irresponsive to the forces with which the keys are depressed, a second performance section which produces music signals by manipulation of keys in a keyboard at levels responsive to the forces with which the keys are depressed, and expression control means which varies the signals from the first performance section under operation of the player, means to lead the signals from the second performance section to the output terminal of the expression control means, and an amplifier and a speaker to convert the signals from both sections into audible sound.

Description

BACKGROUND OF THE INVENTION

This invention relates to an electronic musical instrument, and more particularly an electronic musical instrument including a touch-irresponsive performance section and a touch-responsive performance section wherein the tone signal volumes of the two sections are controlled independently.

An electronic musical instrument is generally characterized by producing various tone colors. However, the electronic musical instrument of a keyboard type heretofore proposed can not separately control the volume of a melody and that of an accompaniment, so that it is limited in the ability of rendering a fully expressive musical performance. With the prior art device, there is installed an expression control device acting as a sort of tone volume controller to give forth dynamics in music behind a circuit point to which there are supplied the signals of a melody and accompaniment with their volumes. Accordingly, when the accompaniment has become a small tone through the expression, the maximum volume of the melody is inevitably limited to the small quantity inconveniently.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an electronic musical instrument capable of varying the tone volume over a broad range in response to the force with which the keys are depressed, and also capable of varying the volumes of a melody and accompaniment separately, so as to display a novel performing effect and render a more expressive musical performance than has been possible with the prior art.

An electronic musical instrument of keyboard type according to the present invention is characterized in that it has a plurality of performance sections including a first performance section comprising a switching circuit which switches signals from a tone generator at a uniform output level by the depression of keys, a second performance section which includes a touch-responsive switching circuit that switches signals from the tone generator at an output level in response to the key-depressing force and a nonexpression device that does not vary the amplitude of output signals from the touch-responsive switching circuit, an expression device which controls the amplitude of output signals from the switching circuit thereby getting out two signals from said first and second performance sections with their amplitude of the signals being controlled separately.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a block circuit diagram of an electronic musical instrument according to an embodiment of the present invention;

FIG. 2 is a block circuit diagram of part of an electronic musical instrument according to a further embodiment of the invention;

FIG. 3 presents a form of touch-responsive switching circuit involved in the embodiment of FIG. 1, showing the manner in which said circuit is actuated when the keys are operated; and

FIG. 4 shows a form of touch-irresponsive switching circuit involved in the embodiment of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

There will now be described by reference to the accompanying drawings an electronic musical instrument according to an embodiment of the present invention. Referring to FIG. 1, numeral 1 represents tone generators such as musical scale tone signal oscillators, 2 an upper keyboard, 3 touch-responsive switching circuits for switching signals from the tone generators at output signal levels in response to the magnitude of a force with which the upper keys are depressed, 4 a tone-coloring circuit consisting of, for example, a filter circuit, 5 an expression selector switch, 6 a nonexpression device consisting of a semifixed resistor only for preadjustment of output levels, 7 an expression device involving a variable resistor operated by a pedal, 8 a lower keyboard, 9 switches for switching signals from the tone generators by operation of the keys in the lower keyboard so as to produce a uniform output level independently of the magnitude of a force with which the keys are depressed, 10 a tone-coloring circuit consisting of, for example, a filter circuit, 11 an expression device consisting of a variable resistor actuated by a foot pedal and operated interlockingly with the aforementioned expression device 7, 12 an amplifier circuit and 13 a speaker. Tone generator 1, lower keyboard 8, switching circuit 9 and tone-coloring circuit 10 constitute a lower keyboard section or a first performance section of a touch-irresponsive type. And tone generator 1, upper keyboard 2, touch-responsive switching circuit 3 and tone-coloring circuit 4 constitute an upper keyboard section or a second performance section of a touch-responsive type.

There will now be described the operation of an electronic musical instrument having the aforementioned arrangement. First in the touch-irresponsive performance section, when a given key involved in the lower keyboard 8 is depressed there is obtained from the output of the touch-irresponsive switching circuit 9 a tone signal having a uniform output level regardless of the magnitude of a force with which the key is depressed. The output signal is then formed by the tone-coloring circuit 10 into a signal having a predetermined tone color. The tone-colored signal is supplied to the expression device 11 for an intensity control to be a musical signal having dynamics and then conducted to the amplifier circuit 12. Next in the touch-responsvie performance section, when a given key involved in the upper keyboard 2 is depressed there is generated from the touch-responsive switching circuit 3 a tone signal having an output level in response to the magnitude of a force with which the key is depressed. The output signal from the switching circuit 3 is then formed by the tone-coloring circuit 4 into a signal having a predetermined tone color. The tone-colored signal is supplied through the expression selector switch 5 to either of the nonexpression device 6 and the expression device 7 to be a musical signal of this second performance section and then conducted to the amplifier circuit 12. Thus, the signals of musical tones from the first and the second sections are conducted to the amplifier circuit 12 to be jointly amplified and sounded through the speaker 13.

When the expression selector switch 5 is actuated toward the nonexpression device 6 there is not afforded an expression control to a signal of a musical tone from the upper key board section but only to that from the lower keyboard section. Since, however, the volume of a tone signal of the upper keyboard section can be varied by the magnitude of a force with which the keys in the upper keyboard 2 are depressed, the tone volume of the signal is varied in musical expression (dynamics) by the operation of the keys. In this case, the volume of the lower keyboard section signal is controlled by the expression device 11 during the musical performance, and the volume of the upper keyboard section signal is controlled by the keys in the keyboard 2 during the musical performance. Accordingly, the tones of the lower and the upper keyboard sections can be separately varied in volume. For example, where the upper keyboard section produces a melody and the lower keyboard section an accompaniment, the volume of the melody is varied in response to finger forces with which the upper keys are depressed and the volume of the accompaniment is varied by the expression device operated by a foot pedal or the like. Therefore the electronic musical instrument of the present invention eliminates inconvenience encountered with the prior art instrument.

When the melody and the accompaniment are to be controlled simultaneously to the same degree of volume, it is only required to actuate the expression selector switch 5 toward expression device 7. In this case, the tones from the upper keyboard section are controlled in musical expression by the expression device 7 to the same degree as those from the lower keyboard section, in addition to the volume control in response to the key-depressing forces.

While the aforementioned embodiment shown in FIG. 1 involves expression devices 7 and 11 for the tone signals of the upper and the lower keyboard sections respectively, there may be provided a common expression device 14 as shown in FIG. 2 for the both section signals, wherein either of the devices 6 and 14 is selected by operation of an expression selector switch 15 for signals to the upper keyboard section. This will also display the same effect as mentioned before.

FIG. 3 shows the relationship of the operation of the key and the touch-responsive switching circuit as used in the upper keyboard section in the aforementioned embodiment. A magnet is attached to each key in the upper keyboard, preferably on the lower surface of the key, and a coil 17 is disposed in an associated position with each key. One end of the coil 17 is grounded and the other end is connected through a condenser 24 to the base of an NPN-type transistor 25. The base is grounded through a resistor 26 and connected through a resistor 27 to a DC source. The emitter of the transistor 25 is grounded through a resistor 28, and the collector thereof is connected through a resistor 29 to the DC source and the base of an NPN-type transistor 30. The collector of the transistor 30 is directly connected to the DC source and the emitter thereof is grounded through a resistor 31 and also connected to the gate electrode of a field effect transistor 33 through a rectifier 32 of a diode or the like. The gate electrode of the field effect transistor 33 is grounded through a condenser 34 and also through a resistor 35 and a normally closed contact 23 of a key switch which are connected in series. The source electrode of the field effect transistor 33 is connected to a corresponding tone generator 37 among the tone generator group 1 as shown in FIG. 1 through a condenser 36 and a key switch 41, and grounded through a resistor 38. The drain electrode of the transistor 33 is grounded through a resistor 39 and connected through a condenser 40 to the following stage, for example, an amplifier.

With an electronic musical instrument arranged as described above, while a key of the upper keyboard 2 remains in a rest position, the magnetic flux of the coil 17 does not vary and the normally closed contact 23 is kept closed. When the key of the upper keyboard 2 is depressed the magnet 18 is brought down to approach the coil 17 at a certain speed and faces it at a predetermined position. When the magnet 18 is drawn near at certain speed, the magnetic flux in the core 19 of the coil 17 is varied with the resultant occurrence of an electromotive force. This electromotive force effects the current which is rectified by the rectifier 32, and charges the condenser 34 and conducted to the field effect transistor which constitute a keyer to switch the tone signal from the tone generator 37. When the key in the keyboard 2 is forcefully depressed, the magnet 18 is drawn near a position to face the coil 17 at a high speed, inducing a great electromotive force in the coil 17. Accordingly, the tone signal from the tone generator 37 is conducted to the succeeding stage in a large amplitude. Conversely, where the key in the keyboard 2 is lightly depressed, the magnet 18 is brought near the coil 17 at slow speed, resulting in a low electromotive force. Thus the tone signal from the tone generator 37 is forwarded to the following stage in a small amplitude.

There will now be described of more details of the circuit of FIG. 3. The electromotive force induced in the coil 17 is amplified by the transistor 25 and then the amplified voltage is taken out of the emitter of the emitter follower transistor 30 and supplied to the gate electrode of the field effect transistor 33, which controls the conduction rate of the tone signal from the tone generator 37. Namely, where there is generated a great electromotive force in the coil 17, the gate electrode is also supplied with a high voltage, producing a large tone signal as an output signal from the keyer (switching circuit 3). When the electromotive force is weak, the gate electrode is supplied with a low voltage, giving forth a small tone signal and accordingly the tone signal of the output becomes small.

Therefore, the volume of the tone signal produced varies in response to the key-depressing force, obtaining large varieties of performance (or the so-called touch-responsive control effect) as is realized on the piano.

FIG. 4 shows a switching circuit 9 according to an embodiment of the present invention. When the key switch 42 is turned on there is formed the emitter circuit of the transistor 43, conducting tone signals from an input terminal 45 to an output terminal 44. When the key switch is turned off, the voltage across the base and emitter of the transistor 43 is inversely biased by source +B.sub.2, producing no output signals from the terminal 44.

As mentioned above, the foregoing embodiment relates to the case where the instrument comprises two performance sections of the upper and the lower keyboard sections, and the upper keyboard section is of a touch-responsive type and the lower the touch-irresponsive type. However, the present invention is also applicable where the performance sections are the left half and the right half of a single keyboard divided into the bass and the treble regions, or where there is provided a pedal keyboard in addition to manual ones. Further, it will be apparent that any of the keyboards may be of a touch-responsive type.

The electronic musical instrument of the present invention can vary the volume of tones over a broad range in response to the force with which the keys are depressed and separately control the amplitude (or the tone volume) of a plurality of signals of musical tones (for example, in combinations of an accompaniment and melody), and is of great use in that it prominently elevates the expression ability of performance and displays a novel performing effect.

Claims

What is claimed is:

1. An electronic musical instrument comprising:

a. tone generators;

b. a first performance section including a first keyboard with keys, switching circuits with input and output sides associated with the respective keys in said first keyboard coupled on the input side to said tone generators and gating tone signals from said tone generators, and a first tone coloring circuit connected to output sides of said switching circuits, said switching circuits and first tone coloring circuit defining the output side of said section;

c. a second performance section including a second keyboard with keys, touch-responsive switching circuits with input and output sides associated with respective keys in said second keyboard coupled on the input side to said tone generators and gating tone signals from said tone generators with output levels responsive to depressing forces on the keys of said second keyboard, and a second tone coloring circuit connected to the output sides of said touch-responsive switching circuits, said touch-responsive switching circuits and said second tone coloring circuit defining the output side of said section;

d. an expression device connected to the output side of said first performance section and controlling levels of signals therefrom, said expression device having also an output side;

e. circuit means connected to said second performance section switching circuits and leading signals from said second performance section to said output side of said expression device;

f. an amplifier connected to the output side of said expression device; and,

g. a speaker to convert signals from said amplifier to sounds.

2. An electronic musical instrument according to claim 1, wherein said circuit means comprises a constant level nonexpression device connected between the output side of said second performance section and the output side of said expression device.

3. An electronic musical instrument according to claim 1 wherein said expression device is a first expression device, and includes an output side, said circuit means comprises a constant level nonexpression device, a second expression device, the output sides of said nonexpression device and said second expression device being connected to the output side of said first expression device, and an expression selector switch connected to both said nonexpression device and said second expression device selectively connecting the output side of said second performance section to either said nonexpression device, or said second expression device.

4. An electronic musical instrument according to claim 3, including a foot pedal so adapted and disposed that said first expression device and said second expression device are interlockingly operated by said same foot pedal.

5. An electronic musical instrument according to claim 1, wherein said circuit means comprises a constant level nonexpression device with an output side which is connected to the output side of said first mentioned expression device, and an expression selector switch selectively connecting the output side of said second performance section to either said nonexpression device, or the input side of said first expression device.