Device For Causing A Tremolo Or Like Effect In An Electronic Keyboard Musical Instrument

Abstract

Each of the playing keys of an electronic keyboard musical instrument is supported so as to be capable of moving back and forth besides turning up and down through a predetermined angle in the usual manner. Typically, the back-and-forth motion of each key is detected photoelectrically, by means comprising a light source, a light-sensitive variable resistor, and an apertured shutter movable in step with the back-and-forth motion of the key to regulate the intensity of the light incident upon the light-sensitive variable resistor from the light source. The output from the photoelectric means is utilized, for instance, to regulate the level of the signal delivered from a tone coloring circuit to an amplifier circuit of the electronic musical instrument so that a tremolo effect can be added to the sound emitted from a loudspeaker connected to the amplifier circuit.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to electronic musical instruments, and more specifically to a novel and improved device for adding a tremolo or other effect to the sound produced by an electronic organ or like keyboard instrument through back-and-forth motion of any of the playing keys of the instrument.

It is well known that in an electronic keyboard musical instrument, the desired tones are produced as the performer depresses the keys. Each of these keys is then lowered against the tensile force of a spring, with the result that an actuating lever extending downwardly from each key operates the corresponding switch housed in a switch box below the key. Thereupon an output signal from the tone generator corresponding to the depressed key is introduced into a tone coloring circuit through a path which has been completed by that particular switch. At the tone coloring circuit the output signal from the tone generator is processed so as to represent the timbre or tone color of any desired musical instrument such for example as a flute or violin. The thus-processed signal is further fed through an amplifier circuit and is then emitted as audible sound from a loudspeaker connected to the amplifier circuit.

Conventionally, in order to produce the effect of tremolo, glide or the like, or to regulate the tremolo speed, the performer of an electronic organ or the like has been required to use his feet while he is playing on the keyboard or keyboards of the instrument with both of his hands. However, such simultaneous manipulation of the digital and pedal keys as well as the switches is so difficult, especially to the unskilled performer, that it has presented a serious bar to his gaining true command of the instrument.

SUMMARY OF THE INVENTION

In view of the noted difficulties of the prior art, it is an object of this invention to provide a novel and improved device for causing a tremolo or other effect in an electronic keyboard musical instrument such as an electronic organ, such that the desired effect can be produced simply by moving back and forth any of the playing keys of the instrument.

Another object of the invention is to provide a device of the character referred to, which can be easily incorporated in an electronic organ or like keyboard instrument without any substantial modification of its construction or without substantially increasing its manufacturing costs.

A further object of the invention is to provide an improved electronic keyboard musical instrument which can be played easily even by a relatively unskilled performer.

With these objects in view and the other ancillary objects hereinafter made apparent, the present invention provides the novel combination in an electronic keyboard musical instrument which includes support means for supporting each of the playing keys of the electronic musical instrument in such a manner that the keys are each capable of moving back and forth besides turning up and down through a predetermined angle in the usual manner. The back-and-forth motion of each key is detected to control specific circuit means of the electronic musical instrument such that a desired effect can be added to the sound produced by the instrument.

In more specific aspects of the invention, the back-and-forth motion of each key is detected photoelectrically, and the pulsating output from the photoelectric detecting means is impressed to the gate of a field-effect transistor connected between a tone coloring circuit and an amplifier circuit of the electronic musical instrument. As the level of the output signal from the tone coloring circuit is thus varied in step with the back-and-forth motion of the key, a tremolo effect is added to the sound being emitted from a loudspeaker connected to the amplifier circuit.

The features which are believed to be novel and characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and mode of operation, together with the further objects and advantages thereof, will be best understood from the following description taken in conjunction with the accompanying drawings which illustrate, by way of example only, a preferred embodiment of the invention and in which like reference characters denote like parts throughout the several views.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a side elevational view showing a digitally operable key of an electronic organ or like keyboard instrument and means directly associated therewith by way of a preferred embodiment of the invention;

FIG. 2 is a schematic top plan view of photoelectric means adapted to detect the back-and-forth motion of the key of FIG. 1; and

FIG. 3 is a block diagram explanatory of the electrical configuration of the embodiment of FIGS. 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The device according to this invention is adaptable for any electronic musical instrument having a bank keys to be digitally played upon for sound production. FIG. 1 illustrates one of such playing keys 10 arranged side by side on a support structure or frame 11 of an electronic organ or the like. The rear end of each key 10 is substantially integrally coupled to an arm 12, hereinafter referred to as the key arm, in accordance with the prior art. The key arm 12 is securely coupled to the upper end of a support 13 of resilient material which typically may be provided in the form of a leaf spring or of a strip of elastomer or the like, while the lower end of this resilient support 13 is screwed or otherwise fastened at 14 to the rear end of the frame 11. In this manner each key 10 is permitted to move back and forth besides being capable of turning up and down like the usual keys of keyboard musical instruments.

A helical tension spring 15 extends between the rear end of the key arm 12 and a substantially Z-shaped member 16 rigidly coupled to the frame 11, so that the key 10 is normally held in its horizontal position as shown in FIG. 1.

A lever 17 has one of its ends coupled to the upper end of the resilient support 13 and the other end fastened to an appropriately apertured shutter 18 shown in FIG. 2. The back-and-forth motion of the key 10 is thus detected through the lever 17 by photoelectric means 19 hereinafter set forth in more detail.

A switch actuating lever 20 extends downwardly from the key 10 into a switch box 21 mounted under the frame 11. Hence, each time the key 10 is depressed, the switch, not shown, within the switch box 21 will be closed in accordance with the prior art to cause an output signal from the corresponding tone generator of the electronic musical instrument to be delivered to a tone coloring circuit via a switching circuit which has been rendered conductive by that particular switch.

At the front end of the frame 11 there is fixedly provided a member 22 to support a stop 23 at its upper end. The stop 23 is somewhat loosely received in a housing of any suitable shape formed on the underside of the key 10, in such a manner that the angle of swing of the key is thereby delimited.

As illustrated in further detail in FIG. 2, the aforementioned photoelectric means 19 mounted on the frame 11 is composed of a light source 24 such for example as a lamp or a photodiode, and a light-sensitive variable resistor 25 such for example as a cadmium-sulphide photoresistor positioned opposite the light source 24 through the apertured shutter 18. The light source 24 is connected to a DC power supply 26, and the light given off by the light source 24 due to the DC power supply 26 is normally cut short by the shutter 18. The aperture 18 formed in this shutter 18 may, for example, be of substantially sectorial shape as is well known to those in the art.

As the key 10 is digitally moved back and forth, as indicated by the double-headed arrow in FIG. 1, the lever 17 coupled to the upper end of the resilient support 13 and fastened to the shutter 18, will cause the shutter 18 correspondingly to move up and down relative to the light source 24 and the light-sensitive variable resistor 25, in such a manner that the intensity of the light incident on the latter from the former is regulated in conformity with the back-and-forth motion of the key 10.

With reference to FIG. 3, the light-sensitive variable resistor 25 can be connected, for example, in the base-biasing circuit of a transistor Tr functioning substantially as an amplifier. One of the terminals, T.sub.1, of the light-sensitive variable resistor 25 is connected to a terminal P which is to be connected to the positive electrode of a DC power supply not shown in the drawings. The other terminal T.sub.2 of the light-sensitive variable resistor 25 is connected to the base of the transistor Tr via a resistance R.sub.1, and the point of connection between the resistance R.sub.1 and the terminal T.sub.2 of the light-sensitive variable resistor 25 is grounded via a resistance R.sub.2.

The collector of the transistor Tr is connected to the aforesaid terminal P, while the emitter of this transistor is, on the one hand, grounded via a resistance R.sub.3 and, on the other hand, connected to the gate of a field-effect transistor 27 via a resistance R.sub.4. The field-effect transistor 27, provided for the purpose of amplitude regulation as hereinafter explained in further detail, has its drain D connected to the output of a tone coloring circuit 28 and its source S connected to an amplifier circuit 29 and thence to a loudspeaker 30.

The keyboard 31 of the electronic musical instrument consists of the bank of digitally operable keys 10 illustrated in detail in FIG. 1. These keys 10 are associated with the respective switching circuits generally designated by the numeral 32, in accordance with the prior art, so that each time any of the keys 10 is digitally depressed, conduction is caused as aforesaid through the corresponding switching circuit to permit a desired output signal from the tone generator circuit 33 to be delivered therethrough to the tone coloring circuit 28.

In the preferred embodiment of this invention, configured substantially as hereinbefore described, each key 10 on the keyboard 31 is turned downwardly on the resilient support 13 against the helical tension spring 15 when digitally depressed in the usual manner, with the result that the switch actuating lever 20 coupled to the depressed key is lowered to close the switch in the switch box 21 thereby causing conduction through the corresponding one of the switching circuits 32 shown in FIG. 3. Thereupon the desired output signal from the tone generator circuit 33 is delivered through the conductive switching circuit to the tone coloring circuit 28, where the signal is processed in the known manner so as to represent the timbre or tone color of any desired musical instrument such for example as a flute or a violin. The output signal from the tone coloring circuit 28 is delivered through the field-effect transistor 27 and the amplifier circuit 29 to the loudspeader 30, where the amplified signal from the amplifier circuit 29 is translated into the desired audible sound.

It is assumed that the shutter 18 of the photoelectric means 19 is so related with the key 10 that when the key is depressed in the usual manner, the light given off by the light source 24 is permitted to irradiate the light-sensitive variable resistor 25 with an intermediate degree of intensity. Since the base-biasing potential of the transistor Tr is determined in accordance with the intensity of the light incident on the light-sensitive variable resistor 25, there can be caused no substantial fluctuation in the level of the output signal from the tone coloring circuit 28 as it travels through the field-effect transistor 27. Hence, as the keys on the keyboard 31 are successively depressed in the usual manner, the musical sound can be produced from the loudspeaker 30 at a preset volume.

In order to add a tremolo effect to the sound thus emitted from the loudspeaker 30, the desired key 10 may be moved back and forth as indicated by the double-headed arrow in FIG. 1 while being held in its depressed position. This back-and-forth motion of the key 10 together with the key arm 12 is converted into the up-and-down motion of the lever 17, also indicated by the double-headed arrow in FIG. 1, through the resilient support 13 coupled to the key arm 12. The shutter 18, FIG. 2, is thus moved up and down relative to the light source 24 and the light-sensitive variable resistor 25.

If now it is assumed that the intensity of the light incident on the light-sensitive variable resistor 25 increases with the upward motion of the shutter 18, then the resistance of the light-sensitive variable resistor 25 decreases thereby resulting in the increase in the base current and hence in the emitter current of the transistor Tr. As a consequence, a high potential is impressed to the gate of the field-effect transistor 27, so that the level of the output signal from the tone coloring circuit 28 increases to cause the corresponding increase in the volume of the sound produced from the loudspeaker 30 via the amplifier circuit 29.

If, on the other hand, the shutter 18 is moved downwardly, the gate-biasing potential of the field-effect transistor 27 decreases through a procedure which will be apparent from the foregoing description, so that the volume of the sound produced from the loudspeaker 30 also decreases.

Hence, as the key 10 is digitally moved back and forth while being held in its depressed position, the loudspeaker 30 emits the tone in a pulsating or tremulous manner by the repetition of the above described procedure. The performer can thus add the desired tremolo effect to his musical performance by use of his hands only.

Although the present invention has been shown and described hereinbefore in terms of a specific embodiment thereof, it is to be clearly understood that the invention itself is not to be restricted by the exact showing of the drawings and the description thereof. For example, while in the illustrated embodiment of the invention the lever 17 and the photoelectric means 19 are provided for each and every digital key of the electronic musical instrument, it is of course possible to provide a single photoelectric means in common to all the keys of the instrument, so as to be properly actuated upon back-and-forth motion of any of the keys. It is also possible to detect the back-and-forth motion of each key not only photoelectrically as in the illustrated embodiment but piezoelectrically or otherwise.

Furthermore, while the back-and-forth motion of each key is utilized to obtain the tremolo effect by correspondingly regulating the output from the tone coloring circuit in the illustrated embodiment of the invention, the device according to the invention is easily adaptable for controlling other circuits designed to give glide or other effects. It will also be apparent to those skilled in the art that the device of the invention can be associated not only with the digital keys but also with the pedal keys as of an electronic organ to produce a desired effect through the back-and-forth motion of the pedal keys. Therefore, the term "key" as used in the appended claims should be understood to be inclusive of both digital and pedal keys.

All these and other modifications, substitutions or changes are intended in the foregoing disclosure. It is therefore appropriate that the invention be construed broadly and in a manner consistent with the fair meaning or proper scope of the claims which follow.

Claims

What is claimed is:

1. In an electronic keyboard musical instrument, the combination comprising a support of resilient material mounted on the instrument, a plurality of elongated keys each resting on said support and swingable with said support as a fulcrum, said support being resilient enough to permit each of said keys to move back and forth in the lengthwise direction of each said key, a plurality of detecting means coupled to said keys for detecting the back and forth movement of each of said keys, and circuit means coupled to the said detecting means for producing a tremolo sound effect in accordance with the detection of the back and forth movement by said detecting means.

2. The combination as defined in claim 1, wherein said support member is coupled at one end to the rear end of each said keys and at the other end to a stationary part of the electronic musical instrument.

3. The combination as defined in claim 1, wherein each said detecting means comprise a light source a light-sensitive variable resistor positioned opposite said light source and an apertured shutter movably positioned between said light source and said light-sensitive variable resistor, said apertured shutter being coupled to one of said keys to move up and down related to said light source and said light-sensitive variably resistor, to regulate the intensity of the light incident on said light-sensitive variable resistor from said light source in accordance with the back-and-forth motion of each of said keys.

4. The combination as defined in claim 3, including a lever fastened to said apertured shutter adapted to convey the back-and-forth motion of one of said keys to said apertured shutter of one of said detecting means.

5. The combination as defined in claim 3, wherein the output from said detecting means is impressed to the gate of a field-effect transistor connected between a tone coloring circuit and an amplifier circuit of the electronic musical instrument to vary the level of the output from said tone coloring circuit in accordance with the back-and-forth motion of each of said keys, whereby a tremolo effect can be added to the sound emitted from a loudspeaker connected to said amplifier circuit.