U.S. patent number 3,659,031 [Application Number 05/070,055] was granted by the patent office on 1972-04-25 for monophonic electronic musical instrument with a variable frequency oscillator employing positive feed back.
This patent grant is currently assigned to Nippon Gakki Seizo Kabushiki Kaisha. Invention is credited to Takeshi Adachi.
United States Patent |
3,659,031 |
Adachi |
April 25, 1972 |
MONOPHONIC ELECTRONIC MUSICAL INSTRUMENT WITH A VARIABLE FREQUENCY
OSCILLATOR EMPLOYING POSITIVE FEED BACK
Abstract
A monophonic musical instrument having a variable frequency
oscillator including an amplifier, a plurality of frequency
determining networks whose input sides are connected to the output
side of the amplifier, a tapped resistor having a plurality of taps
several of which are respectively connected to the output sides of
the frequency determining networks, and a plurality of switching
elements each connected between each of the taps and the input side
of the amplifier thus constituting a positive feed-back loop; a
plurality of key switches; a latching selector having output lines
respectively connected to the switching elements and associated key
switches so that the closure of the key switch makes the
corresponding one of the output lines to deliver a gating signal to
render the corresponding switching element conductive; and circuit
means for providing rising and sustaining characteristics to the
output signal of the oscillator.
Inventors: |
Adachi; Takeshi (Hamamatsu,
JA) |
Assignee: |
Nippon Gakki Seizo Kabushiki
Kaisha (Hamamatsu-shi, Shizuoka-ken, JA)
|
Family
ID: |
13473538 |
Appl.
No.: |
05/070,055 |
Filed: |
September 8, 1970 |
Foreign Application Priority Data
|
|
|
|
|
Oct 10, 1969 [JA] |
|
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44/71889 |
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Current U.S.
Class: |
84/672;
84/DIG.10; 84/702; 984/380; 84/678; 331/179; 984/339 |
Current CPC
Class: |
G10H
5/04 (20130101); G10H 1/22 (20130101); Y10S
84/10 (20130101) |
Current International
Class: |
G10H
5/00 (20060101); G10H 5/04 (20060101); G10H
1/22 (20060101); G10h 001/02 (); G10h 005/00 () |
Field of
Search: |
;84/1.01,1.03,1.11,1.19,DIG.2,DIG.8,DIG.9,DIG.10,DIG.11,DIG.23
;331/179 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Askin; Laramie E.
Assistant Examiner: Witkowski; Stanley J.
Claims
I claim:
1. A monophonic musical instrument which comprises:
a variable frequency oscillator including an amplifier, a plurality
of frequency determining networks whose input sides are connected
to an output side of said amplifier, a resistor having a plurality
of taps a corresponding number of which are respectively connected
to output sides of said frequency determining networks, a plurality
of switching elements each having a control electrode and connected
between each of said taps and an input side of said amplifier thus
constituting a positive feed-back loop, and an output terminal
connected to said output side of said amplifier;
a latching selector including a plurality of key switches, memory
means connected to said key switches and a plurality of output
lines connected to said memory means, each said output line
corresponding to each of said key switches and connected to said
individual control electrode of each said switching elements, and
upon closure of one of said key switches the corresponding one of
said output lines delivering a gating signal to render its
corresponding switching element conductive;
and circuit means connected to said output terminal which is
connected to the output side of the amplifier for providing rising
and sustaining characteristics to an output signal from the
oscillator.
Description
BACKGROUND OF THE INVENTION
This invention relates to a monophonic electronic musical
instrument in which a frequency variation within wide range as well
as required sustaining characteristics and accompanying rising
characteristics of notes can be obtained.
In general, monophonic electronic musical instruments require
usually 32 times the width of (five octaves) a normal range of
frequency variation. But in a CR oscillator utilized in a
conventional monophonic electronic musical instrument the frequency
variation is usually achieved by varying a capacitor C or a
resistance R, with the result that a range of a frequency variation
in one variable element is limited to at most 10 times of width of
a normal range of frequency variation.
For this reason, a conventional monophonic electronic musical
instrument has generally a very narrow frequency range.
Accordingly, in order to widen the range described above, it was
proposed to switch over a plurality of variable elements to make
them variable, but this resulted in a complex and expensive
structure of the monophonic electronic musical instrument.
Therefore, a continuous variation of the frequency over that wide
range was impossible using an ordinary means. While in case a
multivibrator is utilized to widen the frequency range the
bias-control of the oscillation frequency becomes unstable and is
subject to the influence of the fluctuation of the bias caused by
the variation of a voltage and temperature.
A conventional monophonic musical instrument has another big
drawback in that there cannot be obtained a sustained effect of the
tone. It is because the key switch has a function of starting, and
ending of the oscillation, as well as a function of frequency
determination; therefore the tone signal is generated only while
the key switch is kept closed, and consequently no tone signal is
available after opening the key switch.
SUMMARY OF THE INVENTION
Therefore, an essential object of the invention is to provide a
monophonic electronic musical instrument capable of providing wide
frequency range characteristics as well as sustaining
characteristics to an output signal thereof.
It is another object of the invention to provide a monophonic
electronic musical instrument having a circuit for providing
predetermined sustaining and rising characteristics to an output
signal upon closing of the key switch.
It is a further object of the invention to provide a monophonic
electronic musical instrument the characteristics of which are not
affected by variations of voltage and temperature.
The foregoing objects and other objects as well as the
characteristic features of the invention will become more apparent
from the following detailed description and the appended claims
when read in conjunction with the accompanying drawings, in which
like parts are designated by like reference numerals.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a circuit block diagram showing an example of a
monophonic electronic musical instrument according to the
invention; and
FIG. 2 is a detailed circuit diagram showing the circuit of FIG. 1
more concretely.
DETAILED DESCRIPTION OF THE INVENTION
This invention relates to an improved monophonic electronic musical
instrument.
Referring now FIG. 1, the instrument circuit comprises a plurality
of frequency determining networks 1A, 1B, 1C and 1D composed of
capacitors and resistors, a resistor 2 with a plurality of taps
T.sub.l -T.sub.n , a voltage amplifier 3, field-effect transistors
FET.sub.l - FET.sub.n as switching elements, and a latching
selector 4 adapted for selectively gating one of the transistors at
a time. In the latching selector 4 there are provided a plurality
of key switches S.sub.1 S.sub.n in a preference-connection and a
memory circuit M, said key switches being so arranged that only one
of the key switches is connected between a DC source E and memory
circuit M even when more than two key switches are closed.
In addition, the circuit of FIG. 1 comprises further switches
SW.sub.l - SW.sub.n which cooperate with each of the key switches
S.sub.l - S.sub.n , an envelope shaping circuit 5,
frequency-dividing circuits FF.sub.1 - FF.sub.3 , switching
circuits G.sub.1 - G.sub.4 , a filter circuit 6, and tone switches
TS.sub.1 - TS.sub.4 . A variable frequency oscillator VO is
composed of the voltage amplifier 3, a group of frequency
determining networks 1A - 1D, the resistor 2 with a plurality of
taps and field-effect transistors FET.sub.l - FET.sub.n all
connected in a positive feedback loop. When one of the field-effect
transistors FET.sub.l - FET.sub.n is rendered conductive by the
memory circuit M as described hereinafter, the variable frequency
oscillator VO oscillates. Now, assuming that a field-effect
transistor FET.sub.2 is in the state of conduction, the variable
frequency oscillator VO oscillates at an intermediate frequency
which is determined by each of values of respective resistors
between a tap T.sub.2 and the networks 1A and 1B and is between
tuned frequencies of two frequency determining networks 1A and 1B
which are at the nearest of the tap T.sub.2 . When another
field-effect transistor is in the state of conduction, the variable
frequency oscillates in same manner described above but at a
different frequency.
A signal from the variable frequency oscillator VO is directly
introduced successively through switching circuit G.sub.1 and
frequency-dividing circuits FF.sub.1 .about. FF.sub.3 to switching
circuits G.sub.2 .about. G.sub.4 , whereby the oscillator output
signal and the frequency-divided signals are subjected to envelope
controls according to an envelope signal from the envelope shaping
circuit 5. The envelope controlled signals are supplied to the
filter circuit 6 to be given predetermined tone colors, and finally
taken out through the tone switches TS.sub.1 .about. TS.sub.4 .
The latching selector 4 for selectively gating the transistors
performs electrically a function of a lock-and-release push button
switch. When, among the switches S.sub.l - S.sub.n which are
selectively connected to a DC source E, for example the switch
S.sub.2 is switched on, the DC source E is connected only through
the switch S.sub.2 to the memory circuit M even if anyone of the
switches S.sub.3-S.sub.n which are located behind the switch
S.sub.2 is switched on simultaneously. Thus, the memory circuit M
supplies an output gating signal to only the output line TO.sub.2
corresponding to the switch S.sub.2 , thereby rendering the
field-effect transistor FET.sub.2 conductive. After the switch
S.sub.2 has been switched off, the memory circuit M continues to
deliver the gating signal at the output line TO.sub.2 for gating
the field-effect transistor FET.sub.2 so long as another one of the
switches is not subsequently switched on. Therefore, the variable
frequency oscillator VO, as described before, oscillates at the
frequency determined by the tap T.sub.2 .
In FIG. 2, there is shown a detailed circuit diagram which
illustrates a part of FIG. 1. Hereinafter, mainly the operation of
the memory circuit 4 will be described in detail. The memory
circuit M is composed of a plurality of flip-flop circuits, and all
transistors 10 of each of said flip-flop circuits are switched on
to their conductive states in the original state of FIG. 2, i.e.,
before no switches are actuated after the electric power in the
memory circuit is first connected, because both potentials of
collectors 13 of transistors 10 and the potentials of collectors 23
of transistors 20 have increased similarly through a load resistor
14 or 24, but the potentials of bases 22 of the transistors 20 have
not increased so much as the potentials of bases 12 of the
transistors 10 due to the existence of grounded resistor 26. In
such a state, when the switch S.sub.2 is closed, the transistor 10
of the flip-flop circuit corresponding to the switch S.sub.2 is
turned off, while the transistor 20 corresponding to the switch
S.sub.2 is turned on. Now, since the collector potential of the
transistor 10 is kept at a positive potential, it renders the
field-effect transistor FET.sub.2 conductive. This state is kept
unchanged even after the switch S.sub.2 is released back. And next,
when another one of the switches, for example, S.sub.n-1 is closed,
the transistor 10 of the flip-flop circuit corresponding to the
switch S.sub.n-1 is turned off, while the transistor 20 of that
corresponding to the switch S.sub.n-1 is turned on. However, in a
moment of the turning on of the transistor 20, a current flowing
through the coil L immediately increases and a potential of an
emitter common line l suddenly increases by action of an inductance
of the coil L against the rapid current variation. Consequently,
the transistor 20 corresponding to switch S.sub.2 which has been
on, is now off. The sudden increase of the potential of the emitter
common line 1 does not, of course, affect at this moment the now
turned-on transistor 20 of the flip-flop circuit corresponding to
the switch S.sub.n-1 , as the transistor 10 thereof is now kept
stably off by the closing of the switch S.sub.n-1 . The operation
of such a memory circuit M may be more clearly understood from the
description in the U.S. Pat. No. 3,488,515 to Hiyoshi.
In FIG. 1 and FIG. 2, switches SW.sub.1 - SW.sub.n cooperating with
key switches S.sub.1 - S.sub.n are provided for supplying signals
derived from switching on and off the key switches to an envelope
shaping circuit 5. When any one of the switches SW.sub.1 - SW.sub.n
is switched on or off, the envelope shaping circuit 5 produces an
envelope signal having, for example, a rising time 10 miliseconds
and sustaining(decaying) time 1 - 2 seconds, thereby to perform an
envelope control in each of the switching circuit G.sub.1 -
G.sub.4.
Further, although in the embodiment described above there is
provided a variable frequency oscillator VO which has four
frequency determining networks, it is within the scope of the
invention to change the number of the frequency determining
networks as well as the field-effect transistor, and the switching
circuits can be increased or decreased as necessary.
* * * * *