JPS5815986Y2 - Opening/closing control signal generator for electronic musical instruments - Google Patents

Description

[Detailed description of the invention] This invention relates to the improvement of the opening/closing control signal generator in electronic musical instruments.1 Particularly, the opening/closing control signal in which the attack time in the key press envelope expressed by the opening/closing control signal is arbitrarily switched from 5 to 5. Regarding the generator.

Conventionally, when a specific one of a large number of key switches is operated, an opening/closing control signal expressing a desired key press envelope is generated, and a sound source signal of a note name corresponding to the operated key switch is generated. An electronic musical instrument has already been proposed in which the opening/closing control signal is amplitude-modulated with the opening/closing control signal to open and close the opening/closing control signal to lead to the subsequent sound generation system.

In this type of electronic musical instrument, the circuit for generating the opening/closing control signal normally utilizes the charging/discharging phenomenon of a capacitor, and forms a key press envelope that corresponds to the charge/discharge curve. In order to change the attack time in the key envelope, it is necessary to change the charging time constant determined by the capacitance value of one capacitor and the resistance value of the resistor connected to this capacitor.

When changing the charging time constant in this way, it is conceivable to change the composite capacitance value and/or composite resistance value by switching and connecting several capacitors and/or resistors with appropriate changeover switches. In this method, the changeover switch is directly connected to the charging path of the capacitor, which is the path of the key-on signal, so noise is added to the key press envelope, which often causes waveform distortion. 1. It lacks stability and reliability. It has the following drawbacks.

The purpose of this invention is to eliminate this kind of drawback and provide a new opening/closing control signal generator that can generate a key depression envelope with a variable one attack time and little waveform distortion with a simple circuit configuration.

The feature of this device is that the key state signal is received on the base side via the first charging time constant determining resistor, and the emitter side of the transistor is charged and discharged via the second charging time constant determining resistor. The charging time constant is made variable by connecting a capacitor for the charge and controlling the operation and non-operation of the transistor using an attack time changeover switch connected to the collector of the transistor, thereby making the attack time in the key press envelope variable. .

According to this feature, since the first and second charging time constant determining resistors connected to the charging path of the capacitor are indirectly switched via the transistor, which is an electronic switch, it is possible to A key press envelope with variable attack time can be formed without waveform distortion.

Embodiments of this invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the opening/closing function section of an electronic musical instrument equipped with an opening/closing control signal generator according to an embodiment of this invention, where 11, 21; . . . Vessel, 12, 22. . . . indicates a diode type switching circuit which is known per se, and 30 indicates a sustain control circuit.

Each opening/closing control signal generator 11, 21;... is provided corresponding to each key switch Ksw1, KSW2;..., and is a key for instructing the operating state (on/off) of each key switch. Status signal KS1. KS2. An opening/closing control signal KC1, which expresses a desired key press envelope according to .
KC2, . . . are generated respectively.

Each opening/closing control signal generator 11, 21;...
・A common attack time changeover switch AT is provided.

In addition, each opening/closing control signal generator 11.21 is used to switch and control the sustain time in each key press envelope;
. . . are commonly connected to a sustain control circuit 30 including a sustain switch ST.

Furthermore, each switching circuit 12, 22;... is provided corresponding to each switching control signal generator 11, 21;... The sound source signal S1. S2. ...
The opening/closing control signals KC1, KC2, . and is sent to the subsequent sound generation system in the form of a mixed opening/closing output KO.

Next, details of the configuration and operation of the opening/closing control signal generator according to this invention will be explained regarding the opening/closing control signal generator 11.

The opening/closing control signal generator 11 is provided with two charge/discharge control transistors Qt and Q2.

The base of the transistor Q1 is connected to the first charging time constant determining resistor r1 and the key switch K when the key switch KSW1 is turned on.
SW, and is grounded through the key switch KSW.
A key state signal KSφ indicating the on/off state of 1 is applied to the base of the transistor Q1 via the resistor r1.

Further, the emitter of the transistor Q1 is connected to a charging/discharging capacitor C□ via a second charging time constant determining resistor r2, and the collector of the transistor Q1 is connected to the switch AT and a diode when the attack time changeover switch AT is turned on. It is grounded via D11.

The diodes D1□, D21; . . . are backflow insect prevention diodes that eliminate the mutual influence between the opening/closing control signal generators when the attack time changeover switch AT is off.

A discharge time constant determining resistor R1 is connected in parallel to the capacitor C1, and a potential of -V is applied to the emitter of the transistor Q1 via a parallel path of the capacitor C1 and the resistor R1 and the resistor r2.

The collector of the transistor Q2 is connected to the connection point X between the parallel path of the capacitor C1 and the resistor R1 and the resistor r2,
A potential of -V is applied to the emitter of this transistor Q2 via a discharge time constant determining resistor R2.

A diode Dl is also connected to the terminal of the transistor Q2.
A key status signal KSφ; is provided via the key status signal KSφ;

The base of the transistor Q2 is connected to the sustain control circuit 30.
The transistor Q3 is driven by the output of the output transistor Q3, and the sustain switch (usually consisting of a normally closed foot switch driven by a sustain pedal) ST is closed to the a side. When the switch ST is open to the b side, it is driven to be in the on state through the diode D2, and receives a bias potential from the variable resistor VR to be in the off state.

Therefore, the emitter potential of the transistor Q3 becomes the ground potential or approximately -Ve as the movable contact of the sustain switch ST comes into contact with the fixed contact a or b, respectively.

An opening/closing control signal KC1 as shown in FIG. 2 expressing a key press envelope corresponding to the charge/discharge curve of the capacitor C1 is taken out from the connection point X.

Here, a specific operation for obtaining this opening/closing control signal KC1 will be explained.

Now, the movable contact of the attack time changeover switch AT is in contact with the fixed contact, and the collector of the transistor Q1 is maintained at the ground potential, and the sustain switch ST is
The movable contact of is in contact with the fixed contact a, and the transistor Q
It is assumed that the base of 2 is maintained at approximately ground potential.

In this state, when the key switch KSW1 is off, the transistor Q2 is on, and the capacitor C1 is fully discharged through the parallel circuits B and C of the resistors R1 and R2.

Then, when the key switch KSWt is turned on (key pressed), the key state signal KSd' - the ground potential level is taken, so the transistor Ql is turned on, and the emitter of the transistor Q2 is connected to the key switch KSW1$ and the diode 'D1.
Since the ground potential is applied through the transistor Q2
is in the off state.

Therefore, capacitor C0 is connected to transistor Q1 and resistor r
It is charged with a time constant of r2·C1 in the thread path of A1 via A2.

The potential change at the connection point X at the start of charging corresponds to the rising envelope of the opening/closing control signal KC1 at the time of attack, as shown in FIG.

Next, when the key switch KSWI is turned off (key released), the key state signal KSI takes a floating level, so the transistor Ql is turned off and the transistor Q
2 turns on.

Therefore, the charge in the capacitor CI is discharged through the B and C threads.

The discharge curve at this time is a relatively negative and fast attenuation (falling) envelope NS in the opening/closing control signal KC1 shown in FIG.
It is expressed as

Due to the charging and discharging action of the capacitor C1 as described above, an opening/closing control signal KC1 having a key depression envelope as shown by the solid line in FIG. 2 as a whole is obtained at the connection point X.

Next, when the movable contact of the attack time changeover switch AT is brought into contact with the fixed contact a, the collector of the transistor Q1 becomes floating, so the transistor Ql does not function as a transistor, and the P between its base and emitter is
The N junction simply acts as an equivalent diode.

Therefore, when the key state signal KS1 assumes the ground potential level in response to the ON operation of the key switch KSW1, the resistor r1-
) PN junction between base and emitter of transistor - resistance r2
The capacitor C1 will be charged by the thread path of A2 through the .

The charging time constant at this time is expressed as (r1+r2)·C1, so if the charging curve corresponding to this is expressed in the opening/closing control signal KC1 in FIG. 2, it corresponds to the gentle attack envelope shown by the broken line.

In this manner, by operating the attack time changeover switch AT, the attack time in the key press envelope of the opening/closing control signal KC1 can be arbitrarily changed.

In addition, when the movable contact of the sustain switch ST is brought into contact with the fixed contact side (when the sustain pedal is pressed)
, transistor Q2 has a base potential of approximately -Vs.
Therefore, it works as a variable resistor with a resistance value corresponding to -VS.

Therefore, capacitor C1 will discharge with a relatively large time constant controlled by -Vs.

The discharge curve in this case is a relatively gradual attenuation (rise) envelope S in the opening/closing control signal KC1 shown in FIG.
It is expressed as S.

As explained in detail above, this invention can change the charging time constant with a very simple configuration by cleverly using one transistor as both a transistor and a diode.
As a result, it is possible to arbitrarily change the attack time, which is useful for enriching the performance expression of electronic musical instruments.

In particular, the circuit according to this invention has the additional advantage of not disposing an attack time changeover switch in the direct path of the key state signal, and that it can stably supply a variable attack time key press envelope with little waveform distortion.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the opening/closing function part of a photoelectronic musical instrument using an opening/closing control signal generator according to an embodiment of the invention;
FIG. 1 is a waveform diagram showing an example of a switching control signal generated by the switching control signal generator of FIG. 10.20...Opening/closing control signal generator, 12.2
2...Opening/closing circuit, 30...Sustain control circuit, Ql, Q2...Charging/discharging control transistor, rl. r2...°...Resistance for determining charging time constant, R1, R2...
...Discharge time constant determining resistor, C1...Charging/discharging capacitor, AT...Attack time selection switch.

Claims (1)

[Scope of utility model registration request] Generates an opening/closing control signal that expresses a desired key press envelope in response to the operation of a specific one of a large number of key switches, and also generates a sound source signal of a note name corresponding to the operated key switch. The electronic musical instrument is configured to open and close in an amplitude-modulated manner using the opening/closing control signal to lead to a subsequent sound generation system, and includes one charging/discharging control transistor, and first and second transistors connected to the base and emitter of this transistor, respectively. a charging time constant determining resistor; an attack time selector switch connected to the collector of the transistor for operating/inactivating the transistor; and a charging/discharging capacitor connected to the emitter of the transistor via the second resistor. , and a circuit that provides a discharge path to the capacitor when the key is released, and supplies a key state signal corresponding to the operation of the key switch to the base of the transistor via the first resistor, and a circuit that provides a discharge path to the capacitor when the key is released. The opening/closing control signal is generated by controlling charging and discharging of the capacitor in accordance with the charge/discharge curve so as to have a key press envelope corresponding to the charge/discharge curve, and the attack time in the key press envelope is controlled by the attack time changeover switch. An opening/closing control signal generator characterized in that switching is possible by controlling operation/non-operation of the signal generator.