JPS5934949Y2 - Opening/closing circuit of electronic musical instruments - Google Patents

Description

[Detailed description of the invention] This invention relates to the opening/closing circuit of an electronic musical instrument, and more specifically, the invention applies a musical tone signal and a key press envelope signal to the base side of each opening/closing transistor provided corresponding to each of a plurality of tones. The present invention relates to a switching circuit suitable for integration, which greatly simplifies the circuit configuration by supplying these transistors in a mixed form and commonly connecting the emitters and collectors of these transistors.

Conventionally, a circuit as shown in FIG. 1 has been proposed as an opening/closing circuit for an electronic musical instrument.

In the same figure, 10 is a sustain opening/closing unit provided in response to the C note, and 20 is a sustain opening/closing unit provided in response to the C note, and the configurations of both units are representatively shown with respect to the unit 10. They have similar configurations.

Although the drawing only shows two sustain opening/closing units 10.20, normally this type of unit is provided for half an octave (six notes), and their outputs are combined (mixed) and sent to the next stage. It is designed to supply the tone circuit.

By the way, the opening/closing unit 10 includes an opening/closing function section 14 and an envelope generation circuit 16.

The opening/closing function section 14 is provided with an opening/closing transistor Q through which a musical tone signal Ei□ corresponding to the C note is input manually from the input terminal 12 to the base side, and an envelope signal generation circuit 16 is provided on the emitter side of this transistor. When the key switch KSI for C note is turned on and off, a key press envelope signal is supplied from the collector side, and an opening/closing musical tone signal is output from the collector side to the output line 17 via the DC blocking capacitor C2. .

Note that an operating voltage V1 is applied to the power supply terminal 13, R1, R2, and R5 are bias resistances, and R3 is a load resistance.

Further, in the envelope signal generation circuit 16, a resistor R
The potential at the point X, which is connected to the emitter of the transistor Q via 5, changes as follows in response to the on/off operation of the key switch KSI.

That is, when the key switch KS1 is off, the capacitor C1 is charged by the bias voltage (2) of the bias terminal 15 via the resistor R6, so the X potential is approximately equal to (2).

Next, when the key switch KS1 is pressed, the charging voltage of the capacitor C1 is discharged through the resistor R4, so the X potential decreases toward the ground potential with the time constant of C1 and R4, and the key switch KSI is turned on. During this time, it is maintained at approximately ground potential.

Further, when the key switch KSI is released and turned off, the capacitor C1 is charged again with the voltage 2 through the resistor R6, and the X potential increases toward 2 with the time constant of C1 and R6.

(This rising period corresponds to the sustain period during which the sound continues).

The above-described changes in the X potential accompanying key press operations form a key press envelope signal.

The emitter potential of the opening/closing transistor Q changes according to the change in the voltage level of the key press envelope signal, so by appropriately determining the operating conditions of the transistor Q, when a key is pressed, the transistor Q changes according to the change in the voltage level of the key press envelope signal. can be turned on and off at the frequency of E,1.
An opening/closing musical tone signal whose amplitude is modulated by the key press envelope signal can be taken out to the output line 17.

The same operation as described above is also performed in the sustain opening/closing unit 20, and when the musical tone signal Ej2 corresponding to the C note is applied to the input terminal 22, the key switch KS2 corresponding to the C note is turned on/off. When operated, output line 2
7, an opening/closing musical tone signal is obtained in which the musical tone signal E is amplitude-modulated by the key depression envelope signal of the key switch KS2.

Both output lines 17 and 27 are connected to the output terminal 18 via the tone tab switch TS, so both lines 1
The opening/closing musical sound signal obtained in Otsu 27 is sent to the key switches KSI and K.
Mixed output signal E only when S2 are both on and switch TS is pressed.

The signal is then supplied to the next stage timbre circuit.

The conventional switching circuit described above with reference to FIG. 1 has the following problems.

That is, first, base bias resistors R1 and R2, collector load resistor R3, and DC blocking capacitor C2 must be provided for each switching transistor.
The configuration is complicated and it is difficult to realize as an integrated circuit.Secondly, if the key switch KSI is pressed even when the tab switch TS is not pressed, the transistor Q will open and close, which is not rational. .

The purpose of this invention is to solve the problems of the prior art described above, and to provide a switching circuit for an electronic musical instrument that has a simple and rational connection structure and is suitable for implementation as an integrated circuit.

The main feature of this invention is that musical tone signal No. 7 and key press envelope signal are supplied in a mixed form to the base side of each opening/closing I transistor provided corresponding to each of the plural tones, and each transistor The point is that the emitters and the collectors of the two are commonly connected.

According to this feature, since the emitter bias means including the tone tab switch and the collector load means can be provided in common for several transistors, the configuration is greatly simplified, and the switching function section including the switching transistor can be easily integrated.

Furthermore, by setting appropriate emitter bias conditions for the switching transistors using emitter bias means including a tone tab switch, it is easy to configure the operation of the tone tab switch to control the operation or non-operation of each transistor. In this way, it is possible to prevent the corresponding opening/closing transistor from starting the opening/closing operation simply by pressing the key switch, resulting in a rational circuit configuration.

Hereinafter, preferred embodiments of this invention will be described with reference to the accompanying drawings.

FIG. 2 shows an example of an opening/closing circuit for an electronic musical instrument according to an embodiment of the present invention, and 30 and 40 do not show sustain opening/closing units provided for the C note and C note, respectively.

The internal configurations of units 1-30 and 40 are almost similar as shown representatively with respect to unit 30, and only one unit 30 will be described in detail below.

The sustain opening/closing unit 1-30 includes an opening/closing function section 34 and an envelope signal generation circuit 36.

The opening/closing function section 34 includes mixing resistors RIO and R1 at the base.
1 is connected to the opening/closing transistor Q11, and a musical tone signal E1□1 corresponding to the C tone is supplied to the base side of the transistor Q11 from the input terminal 32 via the resistor RIO. Key switch KS1 corresponding to
A key depression envelope signal is supplied from the envelope signal generation circuit 36 via the resistor R11 in response to the key depression operation No. 1.

In this case, the mixing ratio of the signals supplied to the base of the transistor Q11 is appropriately determined by the ratio of the resistors RIO and R11, but normally the signal E1□1 is determined by the threshold voltage level of the transistor Qll when the key switch KS11 is turned on. is chosen so that the amplitude of is not limited.

The envelope signal generation circuit 36 has a resistor R11 and a voltage V.
11, the discharging time constant determining resistor R13 connected between the bias terminal 35 of the resistor R13, the charging/discharging capacitor C10 connected in parallel to this resistor R13, the connection point X1 between the resistors R11 and Rl3, and the key switch KS11. and a charging time constant determining resistor R12 connected to the key switch KS1.
1 generates a key depression envelope signal as shown in FIG. 3 in response to ON/OFF operation.

The key press envelope signal is connected to the connection point X1 as shown in Figure 3.
In FIG. 3, the movable contact of the key switch KS11 is grounded and the bias voltage V11 is applied to the bias terminal 35 by approximately -1.
It shows the change in voltage (X1) when 2V is applied.

Before the switch KS11 is turned on, the capacitor C10 is in a discharged state and the potential at the point X1 is maintained at about -12V.

When the switch KS11 is pressed, the capacitor C10 is charged via the resistor R12, so the potential at the X1 point increases toward OV with a time constant of CIO·R12.

Next, when the switch KSII is released and turned off, the capacitor C10 is discharged via the resistor R13, and the potential at the X1 point drops toward -12V with a time constant of C10.R13.

This period of descent corresponds to the sustain period during which the sound continues.

The key press envelope signal formed by this potential change at point X1 is on the base side of transistor Q11,
For example, it is mixed with a musical tone signal E, 11 consisting of a rectangular wave pulse train swinging from OV to -9V.

Sustain opening/closing unit 40 is constructed and operates in the same manner as described above with respect to unit 30.

Roughly speaking, the musical tone signal E112 corresponding to the note C is input from the input terminal 42 via the mixing resistor (corresponding to RIO) to the base of the switching transistor (corresponding to Qll), while the movable contact is grounded. The key press envelope signal generated from the envelope signal generation circuit (corresponding to 36) in response to the on/off operation of the key switch K S 12 corresponding to the C note is transmitted to Ql via the mixing resistor (corresponding to R11).
It is manually applied to the base of the switching transistor corresponding to l.

On the other hand, the emitter lines 33.43 of the switching transistors of each unit 30.40 are commonly connected, and an operation/non-operation control signal is applied to the common emitter line CE from a common bias circuit including the tone tab switch TS11. It looks like this.

The tone tab switch TS11 is connected between the bias terminal 48 and the common emitter line CE, and the bias resistor R15 is connected between the common emitter line CE and the ground point.

The bias voltage V12 of the bias terminal 48 is set to about -
4, 5■, when the switch TS11 is off, the emitter line 33.43 has a transistor for opening/closing in an inoperable state (even if the key switch KS11°/KS12 is pressed, the transistor does not switch to the signal E, 1...E, 12). When a bias voltage, that is, a non-operation control signal is applied to the switch TSII so that it takes on or off depending on the state (independently), and the switch TSII is on, the emitter line 33, 43 has the same transistor in the operating state (the key switch KSII, When KS12 is pressed, a bias voltage, that is, an operation control signal, is applied so that the transistor turns on and off according to the signal E1□1.E, ]2.

Furthermore, the collector lines 37 and 47 of the switching transistors in each sustain switching unit are also commonly connected.
A common load resistor R14 is connected between the common collector line CC and the ground point, and a common output terminal 38 is further connected to the common collector line CC.

Here, to explain the overall operation of the circuit in FIG. 2, first, if the tone tab switch TS11 is in the off state, each switching transistor of each unit 30, 40 is in an inactive state, so the output terminal 38, no musical tone signal is obtained.

Next, when the tab switch TS11 is pressed to turn it on, each opening/closing I transistor enters the operating state, and when any key switch is pressed, the transistor is turned on and off at the frequency of the human-powered musical tone signal.

Therefore, the key switch KS11. A musical tone signal (E, 1□ or E,
An opening/closing musical tone signal Eo1 obtained by amplitude-modulating I2) with a key press envelope signal is obtained at the output terminal 38.

When both key switches KSII and KS12 are pressed, the output musical tone signal E is a mixture of the opening and closing musical tone signals of the collector lines 37 and 47.

11 is obtained. Output musical tone signal E. 11 is appropriately supplied to the next stage tone color circuit.

As described above, in the switching circuit according to this invention, the collector load resistor R14 can be commonly connected to a plurality of switching transistors, and the emitter bias circuit can also be provided in common to those transistors. It can be seen that the circuit configuration is extremely simplified and can be easily realized as an integrated circuit by using a common collector, for example.

Furthermore, when the tone tab switch TSII is in the OFF state (that is, in the illustrated example, there is no need to generate the C note and C1 note), each opening/closing I/transistor will not open/close, no matter how hard you press the key switch. This reduces wasteful power consumption and enables rational circuit operation.

Figure 4 shows an example of a specific switching circuit constructed by applying the circuit in Figure 2. Just looking at the circuit diagram, the circuit configuration is simple despite the large number of transistors, making it suitable for integration. It can be seen that it is.

In FIG. 4, the same reference numerals as in FIG. 2 indicate the same or corresponding parts.

The characteristic of the circuit shown in FIG. 4 is that the musical tone signal E,1 corresponding to the D note is
3 is provided with a circuit that performs sustain opening/closing processing to generate an opening/closing musical sound signal E corresponding to a flute sound.

1□ and the square wave musical tone signal E, 1□E
, 12. Waveform conversion circuits 61, 62, and 63 that generate sawtooth wave sound signals by integrating E and 13, respectively.
are provided respectively, and a circuit for sustaining and opening/closing the respective outputs is provided to generate an opening/closing musical tone signal E corresponding to a string sound.

The opening/closing musical tone signal E is the point at which L2 is obtained.

In the circuit for obtaining 1□, 32, 42.52 are input terminals for square wave musical tone signals corresponding to C note, C note, and D note, respectively, and RIO, R20R30 are input terminals 32. 42.52 and switching transistor Qll, Q
12. These are mixing resistors inserted between each base of Q13.

Further, 3545 and 55 are bias terminals to which a bias voltage 11 is applied, and each terminal receives an envelope signal via a C note key switch KSII, a note key switch KS12, and a D note key switch KS13. Generating circuits 36, 46, 56 are connected.

The key press envelope outputs of each envelope signal generation circuit 36, 46, and 56 are connected to mixing resistors R11, R21, and
Transistors Qll, Q12 . Q1
Guided by 3 emitters, flute tab switch TS11
When is closed, the corresponding musical tone force E,..., E,
]2. E and 13 are opened and closed in a mixed manner, respectively,
As a result, the sustain opening/closing output E corresponding to the flute 1 sound is output to the output terminal 38.

1□ can be obtained. On the other hand, the opening/closing musical tone signal E corresponds to the string tone.

] 2, musical tone human power E, 11.
E, 12°E, 13 are respectively waveform conversion circuits 61.6
2.63 to the switching transistor Q14. through the mixing resistors R40, R50, R60. Q15. Q16 and the envelope signal generating circuit 36.
The key press envelope signals of 46 and 56 are sent to the I transistor Q14 through mixing resistors R41, R51, and R61, respectively. Q15. When the string tab switch TS12 is closed, the sustain opening/closing operation similar to that described above is performed to output E to the output terminal 48.

It is designed to take out 12. Furthermore, key switch K
S12. Each movable contact of KS13 is grounded,
R24 is a common collector load resistance, R25 is a common emitter bias resistance, and the bias voltage value is V1□.

■1□ may be similar to that described with respect to FIG.

Although this invention has been described above in detail with reference to specific embodiments, it will be obvious that various improvements and changes may be made without being restricted to the above-mentioned examples when implementing this invention.

For example, the conductivity type of the switching transistor is as shown in the figure (
The envelope signal generating circuit may be of the opposite type (NPN type), and other types of envelope signal generating circuits may be used.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an example of a conventional switching circuit, and FIG. 2 is a circuit diagram showing an embodiment of the switching circuit of this invention.
Figure 3 is a waveform diagram showing an example of an envelope signal;
2 is a circuit diagram showing an example of application of the circuit of FIG. 2. FIG. Explanation of symbols, Qll...Switching transistor,
R10, R11... Mixing resistance, Tsll...
...Tone tab switch, E, 1□...Musical tone signal, R81F song/key switch, 36...Envelope signal generation circuit.

Claims (1)

[Claims for Utility Model Registration] (a) A first musical tone signal corresponding to a musical tone of a certain pitch and a first musical tone signal generated in response to an on/off operation of a first key switch for opening and closing the first musical tone signal. (b) a first opening/closing transistor which is supplied to the bass side in a mixed form with a second key depression envelope signal; and (b) a second musical tone signal corresponding to a musical tone of another pitch and this second A second opening/closing transistor is supplied to the base side in a mixed form with a second key press envelope signal generated in response to an on/off operation of a second key switch for opening/closing a musical tone signal. The emitters of the first and second switching transistors are commonly connected to each other, and an operation/non-operation signal generated in accordance with the on/off operation of the switch is applied to the common connection point. 1. A switching circuit for an electronic musical instrument, characterized in that the collectors of the first and second switching transistors are commonly connected to each other, and a switching musical tone signal is extracted from the common connection point.