DE1772626A1 - Switch arrangement for electronic musical instruments - Google Patents

Description

Patent attorney EHpl.-lno.R.BeQtzu.

JÄ " 81-13.617PH 23.3.1970

Switch arrangement for electronic musical instruments

The invention relates to improvements in switch assemblies for electronic musical instruments.

In general, with electronic musical elements, a system is used as a switch arrangement, with the aid of which a number * ■■ ' of signals of different frequencies can be selected in a suitable manner and combined or mixed with one another by actuating keys belonging to a keyboard combined with the switch arrangement to a desired tone. , to create.

In the usual design, such a switch- < arrangement an electronic amplifier element, a manually operated switch, such as a key switch for control. tion of the electronic amplifier element and a circuit that acts as a cold effect for the output signal characteristic prolonged fading effect and therefore. Follow acts as a holding circle or as an envelope forming circle.

■ ■■ · ■■ -. *. ^ v '.;

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Such an arrangement represents, as will be explained in more detail below is explained, represents a type of gate circuit and will therefore be referred to below as a keeper circuit. The basic principle Such a switch arrangement consists in that an output signal is obtained by pressing the buttons, the amplitude of which is not an instantaneous ego, but gradually decreases.

When using such switch arrangements in electronic musical instruments, however, there is a risk that a leak signal will occur at the output terminal when the key switch is open or the instrument at all is not played, resulting in a no longer negligible noise signal. This fact has at The construction of electronic musical instruments led to serious difficulties.

The aim of the invention is therefore to provide a new and insofar indicate improved switch arrangement for electronic musical instruments that on the one hand the suppression of such Lec! csignale to a minimum and on the other hand the use of a miniaturized switch arrangement using ' Transistors and with simultaneous protection of these transistors from damage is possible.

For this purpose, according to the invention, an asymmetrical component, i.e. a component in which, as for example with einwr pn-

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Junction diode, the forward-voltage-current characteristic is asymmetrical to the corresponding reverse "characteristic, coupled to the input branch of an amplifier element, such as a transistor, and thus all of the above-mentioned goals are achieved. The amplifier element and the asymmetrical Component synchronously with the opening or closing of switches, such as key switches, bias voltages are applied and thus a first or a second bias state is created. In the first bias state, the asymmetrical component is biased in reverse direction and the amplifier element in such a way that its gain essentially to zero, on the other hand, the asymmetrical component is biased in the forward direction during the second bias addition i'iid the amplifier element in such a way that its gain assumes a predetermined value voltage and the switches combine a circuit with a time constant that delays the transition from one bias state z, u to the other bias state when switching the switches from the "on" to the ^H eus position by a predeterminable period of time.

Further objects, features and advantages of the invention will become apparent from the following description in conjunction with FIG See drawing; show it:

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•. 4 -

Fig. 1 is a circuit diagram for a conventional switch arrangement

for electronic musical instruments; 2 shows a circuit diagram for a first embodiment a switch arrangement according to the invention for

electronic musical instruments and FIG. 5 shows a circuit diagram for a second embodiment of a switch arrangement according to the invention for electronic musical instruments _{or the like}

1 shows a conventional switch arrangement of the previous type, the reference number 1 being a tone generator, the reference number 2 being a tranaistor, the reference numbers 5 and 6 being a bias voltage, the reference number 7 being a LT3twtäcretand and the reference number θ being an EmitterwJ.dorstr. nd denote Moreover, for producing the above-mentioned Halteeffektcn a circuit Ί vorgecehen, the auo a Wideratrnd 9 ^nd is a Kondenßntor 10th + V ₁ denotes a voltage source for the operation of the transistor 2 and rait + V ₀ denotes a voltage source which supplies the emitter of the transistor 2 with a reverse bias voltage. The reference number J> denotes a key switch that can be closed by pressing the button down. The reference number "11 int denotes a resistor and the reference number Ic denotes an output terminal. In addition, there is usually a resistance between the line, generator 1 and the node, which, however, is not shown in FIG. 1"

When operating, the emitter-base barrier layer 00983 U / 0660 BAD ORIGINAL is first applied

_ 5 * ■

of the transistor 2 _{strongly biased in the reverse direction by the voltage jellyfish + V 2} , the key switch 3 is in its open position

In this way, the transistor 2 remains even if

him an input signal voltage E _{0 from the tone generator 1}

is supplied, non-conductive for this input signal voltage, so that this input signal voltage E is essentially not passed on to the output source 12. However occurs ■ the output terminal 12 has a weak leak signal. This The leakage signal is likely caused by the input

Signal voltage E _a reaches the output terminal 12 via the junction capacitance 14 between the collector and the base of the transistor 2

If the key switch 3 is then closed, the emitter-base blocking layer of the transistor 2 is slightly biased in the forward direction, and the transistor 2 can take over its normal switch function and thus _{forward the input signal voltage E n} to the output terminal 12.

In the switch arrangement described above, the transistor 2 is switched in a switched manner by opening or Closing the key switch 3 non-conductive or conductive and is able to with respect to the output signal of the tone generator 1 in to act as a switch gate in the manner described above

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in an electronic musical instrument which is _a B. an electronic organ comprising such a plurality of keys, the severe disadvantage that an audio signal of dom Tongeneratnr 1 is a high probability audible even if none of the keys is depressed since the geschlosssn open- -Ratio (i.e. the ratio ^s _e i _n / ^s " _U3 between the voltage level u S, .. of the output signal that occurs at the output terminal 12 when the key switch j5 is closed, to the voltage level S"., "Of the leakage signal when the key switch is open 3 ^ m of the output terminal 12) is au goring .

In addition , a signal voltage E_ is constantly supplied to the node 13 from the tone generator 1, and the emitter breakdown voltage of the transistor 2 is not very high. As a result , the emitter junction of the transistor 2 has a high tendency to breakdown,

With the invention, these disadvantages of the conventional switch arrangement are now to be eliminated. In one embodiment of the invention, an asymmetrical component, such as a diode, is inserted into the base branch of the transistor, and means are also provided which, in synchronism with the open or closed state of a switch, such as a key switch, bias the diode into Feed backwards or forwards. In this way, when the key switch is in its open state , the diode presents a high impedance , creating a

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the signal fed to the base of the transistor is considerably weakened will. Such a signal weakening then leads to an increase in the open / closed ratio and to lessen the difficulties associated with Emitter barrier "perforated»

In FIG. 2, such a first embodiment is required Invention illustrates, viobsi oils reference number plan o inen Tone generator that generates a square-wave output signal,

The decimal number 32 denotes a pn junction diode connected to the tone generator 21, the reference number 22 denotes an npn transictor, the base of which is the output signal of the tone generator 2 via the diode 32, and the reference number 27 denotes a leakage resistance, one end of which has a positive one Voltage source + V, and the other EmO of which is connected on the one hand to the collector of transistor 22 and on the other hand to ri.ner output terminals 32. The Besugo number 2h denotes a circuit for generating a HUl !! curve, which only consists of a resistor 28 and a capacitor 29 and is connected to the emitter of the transistor 22 via an emitter resistor 31. The reference number 2p denotes a key switch connected to the emitter of the transistor 22 via resistors 50 and 31 for controlling the bias conditions for the transistor 22 and for the diode 32. The reference numbers 25 and 26 denote bias resistors fUi * the transistor 22, and with + V ₁ ^ is a voltage source for the operation of the circuit 24 iAir envelope curve formation and for biasing the diode

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in the reverse direction via the resistor 25 and another Resistor 28 denotes when the key switch 23 is open.

Next, the mode of operation of the switch arrangement or the holding circuit described above is entered into. Initially, the diode. "52 with the key switch 25 open via the V / i resistors 25 and 28 from the voltage source + V ^, the positive potential of which is greater than the peak value The capacitor 29 is also charged to approximately the voltage + V ^, and likewise the potential at the node 35 is essentially equal to + V ^. The potential + V, is equal to the potential + Vjj or less selected. This means that the transistor lot 22 biased DAFL it operates in Reststromgebiot or at low power in the vicinity thereof, and therefore, its gain is substantially zero. at the connected to the base of the transistor 22 the node 3 ¹ * A signal arrives which is attenuated by the high impedance of the diode 32, which is biased in the reverse / hardness direction, since the impedance between the node point 34 and the earth potential or reference potential is less than the reverse impedance of diode J2. In this way, the attenuated signal cannot cause the emitter junction of the transit gate 22 to break down, and therefore, unlike in the conventional circuit, its transmission to the output terminal 33 is essentially prevented.

If the key switch 23 is then closed, so

the potential at node 35 becomes within a short range

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Duration, which depends on the product of the capacitance of the capacitor 29 and the value of the resistor 30, since the fourth of resistor 30 is very small compared to the value dee resistance 28, equal to the earth potential “At this moment the diode 32 is forward biased, and the operating point of the transistor 22 comes into its active range, so that the transistor 22 with a predetermined gain begins to work as an amplifier and the output signal of the tone generator 21 reaches the output terminal 33. Since the diode 32 is forward biased as mentioned above, it is not involved in any such signal transmission Way against.

Next, the key switch 23 is back in its transferred to the open state. At this point in time, the potential at the node 35 does not arise immediately its initial value of essentially + V ^ back «Rather takes this potential at the node 35 only gradually and in accordance with the charging characteristics of the capacitor 29, which essentially depend on the product HC, to be addressed as a time constant, of the value R of the resistor 28 and the Capacitance C of the capacitor ;; 29 depends. As soon as the potential at the node 35 finally the value + Vj. reached again, both the diode 32 and the transistor 22 are located back to their original pre-tensioned state, and thus the output signal of the tone generator 21 is prevented from being passed on to the output terminal 33.

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Therefore, the transistor 22 does not immediately return to its original bias state when the key switch 23 is opened. This means that the pre-opening state for the transistor 22 when the key switch 23 is opened gradually changes from the state that is imposed on it when the switch 23 is closed, via a predeterminable transition state to the permanent state when the switch 23 is open, so that at the output terminal 33 even when the switch 23 is open, an output signal is still present for a predeterminable period of time. The amplitude of the output signal maintained in this way decreases essentially exponentially and in accordance with the transition behavior of the upstream timing element for the envelope curve formation, so that what is known as an envelope curve forms in the output signal. Such an envelope curve in the signal is of great importance for every electronic musical instrument The generation of a natural sound and the generation of a solo envelope curve for the signal is precisely the reason why, as mentioned above, a combination of a key switch with an electronic amplifier element and a circuit for the envelope curve formation is used instead of a key switch alone.

. The cause of the increase in the open / closed ratio can be stated as follows: The capacitance between the electrodes of the diode 32 and the impedance between the node 35 and the grounding point are a type of high-pass filter

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equivalent, so that the lower harmonics correspond Components in the right clrifron output signal of the tone generator are filtered away while the higher harmonics pass through this filter. Those let through in this way higher harmonic components of the tone generator signal are then in a further Hoctfipaßfiltor ous the Collector junction capacitance of the transistor 22 and the impedance between the output demnio 33 and the grounding point filtered again before they reach output terminal 33 » In this way, the output cleric 33 only appears a small component of the output signal de3 Tongenerntorn 21 consisting of extremely high harmonics However, the signal that is present in high constituent parts has itself then, if it is boosted in the subsequent shift stage, none sufficient power to operate a loudspeaker. aside from that is the human ear even when loudspeakers come through such a signal should be set in motion for these higher harmonic components of the original tom; Jgnole3 does not sensitive.

As mentioned above, there are essentially no lower harmonic or audio-frequency components of the signal at the node ~ jh , and even these very weak audio-frequency components are further attenuated as they pass through the collector · boundary layer capacitance. As a result, the tension level S _atie des nn is the starting ski emme

aUo

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Locksignales very low "occurs and the open-close Verhältnls (S _oin / 3 _u) increases ₀ This is one of the objects of the invention reached

If you put the treated in Oer preceding EeSchreibung AusfUhrunßcform the invention corresponding to Fig. 2 of the drawing is based, it shows en itself "that a satisfactory operation of such an arrangement 1st possible when orsichtlichen the individual components and voltages in the following from the table Λ V / else dimensioned <.

Tabel

Scheltel value of the rectangular output signal of the tone generator diode 32
Transistor 22

Voltage source + V, voltage source + V ₂ . Resistor 25 Resistor 26 Resistor 27 Resistor 28 Resistor 30 Resistor 31 Capacitor Z $

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10 V 183.473 npn ~ Siliziura transistor 230 * 58 12 V 10 V 2Ok-O.

80 k Jl.

400 JL 50 k-tsp 6? Jl 3.2 k Jl 50 /

BATH ORIGINAL

In a circuit according to FIG. 2 with those in the above Table 1 compiled parameters is the open ge « closed ratio at a signal frequency of 1 kHz in a range from 80 to 90 dB. Here is the signal level with reference to the peak-to-peak value of the signal voltage eaten. From this measurement, the advantageous effect of the circuit according to FIG. 2 compared to the circuit can be seen at the same time according to Fig. 1, since in this circuit at best an open "Goschlock ratio" of about 50 dB can be achieved.

The second embodiment of a switch arrangement according to the invention illustrated in FIG. 3 differs from the embodiment illustrated in FIG. 2 in that an electronic switch implemented in a collector circuit is used.

In Fig. 5 "the collector of a tranintor 42 is grounded via a load resistor 47 and a tone generator 41 is connected as a signal source between ground and a diode 52 connected to the base of the transistor 42 at a node 54. With the emitter of the transistor 42 is connected an emitter resistor 51 is connected to a circuit 44 which forms an envelope curve and consists of a resistor 48 and a capacitor 49. A resistor 50 is inserted between a node 55 and an output terminal of a key switch 43, the other output terminal of which is connected to a potential source -V ₅

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At nodes 5 ^ and 55 there is a bias voltage resistance. The transmission of the output signal from the tone generator 41 to an output terminal 53 is controlled by the key switch h'ß . Such a switch arrangement not only allows the desired holding effect to be produced, but also results in a satisfactory open-gas closure ratio and can substantially reduce the risk of an emitter-protective layer breakdown.

In a practically executed example TUr one Circuit according to Flg. 3 a satisfactory work orphan could be achieved with the parameters compiled in Table 2 below.

Table 2

Peak value of the rectangular output signal from the tone generator 41 Diode 52 Transistor 42

Resistor 45 Resistor 47 Resistor 48 Resistor 50 Capacitor 49 voltage source -V, -

IO V 1S1473 npn silicon transistor 2SCI58 5 kO-200 Jl 40 kJX 50 SL 50 a 12 V

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The exemplary embodiments described above for according to the invention Holder arrangements contain bipolar as amplifier elements Transistors, namely npn transistors, and as unbalanced Bauelercenta diodes with a single ρα transition, however Ii. {gt os obvious to the skilled person that one can instead also unipolar transistors, such as surface field " el'fekt transistors or diodes with a large number of in series pn junctions connected to one another or a transistor or any other link in which senior ' and non-conductive areas follow one another, can also use a tone generator in the examples All signal sources are supplied with a rectangular output signal and shown, However, a signal source with a sinusoidal output signal can easily be used instead Find use, There are also other variations of the examples described possible without departing from the scope of the invention to leave.

Claims (8)

Patent Attorney Dlpl.-Ιηα. Π. Beetl U. Olpl.-tnr. ι ^ mpredlt 81-13.617P-DfH (6) 03/23/1970 New claims 1 to θ 1. Switch arrangement for transmitting one to the input of a Amplifier stage supplied via a Qleiohriohterelement Signals to the output of the amplifier stage alt help one the so-holder controlling the amplifier stage, thereby. marked that the Sohalter the rectifier element by electrical means in the catfish controls that it alternates with conductive amplifier stage a bias in the forward direction and, when the amplifier is blocked, a bias in the reverse direction. 2. Switch arrangement according to claim 1, characterized by « that the switch consists of an actual switching element and a delay element that keeps the amplifier stage in the conductive state for a predeterminable period of time after the switching element has been opened, but keeps its output signal gradually falls off. 3. Switch arrangement according to claim 1 or 2, characterized in that the amplifier stage contains a transistor. 00983W0660 BATH ORIGINAL 4. switch arrangement naoh one of claims 1 to j5, daduroh characterized that the CUeichrichterelement a A semiconductor device which contains at least one barrier layer having a cross-flow effect. 5. Switch arrangement according to claim 3 »characterized in that dad the rectifier element is a semiconductor diode with a p-n junction is so connected to the base of the transistor is that the forward direction of the p-n junction is the same as that of the p-n junction between emitters and base of the transistor. 6. holder arrangement according to claim 2, characterized in that that the amplifier stage contains a transistor, that the Oleichriohtereleiaent has a p-n junction and so on the base of the transistor is connected so that the forward direction of the p-n junction is the same as that of the p-n junction between the emitter and base of the transistor that the switch between the emitter of the transistor and the a common reference potential is that the delay element a resistor located between the emitter of the transistor and a supply voltage source and a resistor between de »emitter of the transistor and the common reference potential containing capacitor and that between the The base and the emitter of the transistor have a resistor 009834/0660 is «which adds the p-n junction of the rectifier element with the switch closed in the forward direction and with the switch open in the reverse direction. 7. Switch arrangement according to claim 2, characterized in that that the amplifier stage contains a transistor and a resistor lying between the collector of the transistor and a common reference potential, that the rectifier element has a p-n junction and so to the base of the Transistor is connected that the forward direction of the p-n junction is the same as that of the ß-n junction between the emitter and base of the transistor that the switch between the emitter of the transistor and a supply voltage source is that the delay element between the Emitter of the transistor and a common reference potential lying resistor and a capacitor lying between the emitter of the transistor and the supply voltage source contains and that a resistor is inserted between the base and the emitter of the transistor, the p-n junction of the rectifier element in the forward direction with the switch closed and in the reverse direction with the switch open pretensioned. 8. Switch arrangement according to one of claims 2, 6 and 7, characterized in that the switching element is mechanically connected to one of the keys of an electrical musical instrument. ^009834/0660 BADORiGlNAt