05/510633

12/30/1975

09/30/1974

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U.S. Philips Corporation (New York, NY)

84/675

84/715, 984/338, 84/685

G10H1/20; G10H5/02; G10H1/02

84/1.01,1.03,1.17,1.22-1.24,DIG.11,DIG.22

3743756	METHOD OF PRODUCING TONES OF A PREFERABLY SUBSTANTIALLY EQUAL-TEMPERED SCALE	July 1973	Franssen et al.
3808345	APPARATUS FOR PRODUCING TONES OF A MUSICAL SCALE	April 1974	Franssen
3824325	ELECTRONIC MUSICAL INSTRUMENT CAPABLE OF TRANSPOSING	July 1974	Obayashi et al.
3877337	ELECTRONIC MUSICAL INSTRUMENT CAPABLE OF TRANSPOSITION	April 1975	Obayashi et al.

Hix L. T.

Witkowski, Stanley J.

Trifari, Frank Cohen Simon R. L.

What is claimed is

1. Musical tone generating circuit comprising a single master oscillator, a first plurality of digital dividers connected to said master oscillator, each of said digital dividers providing a single tone output of a musical scale, a switching device means having inputs connected to each of the outputs of the first plurality of dividers and having an output for selectively providing one of said single tones as an output signal, a second plurality of digital dividers connected to the output of said switching device means for providing lower frequency musical output tones, a plurality of signal controlled adders each connected to a different combination of outputs of said second plurality of dividers, and means for selectively applying control signals to said adders, whereby chords are selectively provided, and whereby the key of said chords from each of said adders is selectively transposed by operating said switching device means.

2. Circuit as claimed in claim 1, wherein the adder circuits are in the form of gate circuits.

3. Circuit as claimed in claim 1, wherein the adder circuits of all the types of chords are combined to form a matrix.

4. Circuit as claimed in claim 1, wherein the treble tones are derived from the first tone generator.

5. Circuit arrangement as claimed in claim 1, further comprising a third plurality of digital dividers provided between the master oscillator and the first tone generator, and a second switching device means connected between the third and first plurality of digital dividers for selectively connecting the input of the first tone generator to any one of the outputs of the third plurality of digital dividers.

6. Electronic musical instrument provided with a circuit arrangement as claimed in claim 1.

BRIEF SUMMARY OF THE INVENTION

The invention relates to a circuit arrangement for generating tones of a musical scale for use in electronic musical instruments provided with one master oscillator, the output of which is connected to a generator which has a plurality of outputs. The signals at these outputs form the scale.

Such a circuit is described inter alia in the Netherlands Patent application 6,802,134 corresponding to U.S. Pat. No. 3,743,756 in which the signal of the master oscillator is applied to a series of frequency dividers from which the pulse trains required for building up a desired tone of the scale are derived and are added in a gate circuit to produce the desired tone. The aforementioned application also describes how tuning the master oscillator in steps results in transposition without affecting the ratio between the pitches of the tones of the scale.

According to the invention a second tone generator is provided, the output of which can be connected via a switching device selectively to any of the outputs of the first tone generator.

One of the resulting advantages is that the step function switching of the master oscillator, the frequency of which is to be set for each separate step and obviously can vary differently for each step, is replaced by stepwise switching to one of the outputs of the first tone generator, the frequencies of which are in a fixed relationship to one another so that variation is precluded.

For the purpose of this specification a tone generator is defined as a circuit arrangement in which from a single frequency a plurality of different frequencies may be derived.

In this specification the term "frequency" is to be understood to mean pulse recurrence frequency, i.e., the number of pulses per second.

In another embodiment of a circuit arrangement according to the invention given outputs of the second tone generator, which provide the low-frequency tones with the possible interposition of additional divider stages, are each connected to an output of an adder circuit, at the output of which an associated chord is produced.

This provides the advantage that the number of adder circuits required does not exceed the number of different types of desired chords, that is to say for example one adder circuit for the major-third chord or major chord, one for the minor-third chord or minor chord, one for the dominant seventh chord, one for the diminished seventh chord and possibly one for the augmented triad or another chord. This type of chord formation is used, for example, in accordions and some types of organs. Hitherto for this purpose mechanical linkages operated by keys have been used. Not only are these mechanisms expensive and complex, but also it is difficult to design them so as to avoid noise.

Obviously such mechanical linkages may be replaced by electronic circuits, however, the latter require either large numbers of contacts, at least three for each chord, or a switch and an adder circuit for each chord, which means that an accordion having 120 bass buttons requires 120 multiple switches or adder circuits. The circuit arrangement according to the invention needs only six multiple switches or six adder circuits in the aforementioned case.

In a further embodiment of a circuit arrangement according to the invention the adder circuit is a gate circuit.

Obviously the adder circuit need not be a gate circuit but may comprise resistors, however, this has the disadvantage that signal losses may occur.

In another embodiment of a circuit arrangement according to the invention the adder circuits for all types of chords are united to form a matrix. This provides a simple structure which may readily be manufactured in integrated circuit form.

Obviously in such an instrument the treble tones must be capable of being separately actuated. For this purpose in a further embodiment of a circuit arrangement according to the invention the outputs of the first tone generator may advantageously be used to produce the treble tones, possibly with the interposition of additional divider stages. In this specification the term "treble" is to be understood to mean the keyboard which normally is played with the righthand. This may have a range of any desired number of octaves.

The interposition of additional divider stages is necessary in a tone generator as described in the above-mentioned U.S. Pat. No. 3,743,756. If a tone generator is used of the type described in Netherlands Patent Specification 7,109,138 corresponding to U.S. Pat. No. 3,808,345 which comprises 12 separate frequency converters, each also consisting of a series of dividers-by-two. To an input of each divider-by-two a tone of the master oscillator is applied. Each divider-by-two has a first output at which a tone is produced which is lower by one simitone than the tone at the input and which is connected to the input of a second frequency converter and so on. The dividers-by-two serve not only to produce the tone at the first output but also, by means of gate circuits, produce the musically suitable octave tones of the tone at the input. Obviously the output may be used directly to produce the treble tones.

In such an instrument transposition naturally is impossible. If the possibility of transposition is to be included, according to another embodiment of a circuit arrangement according to the invention, a third tone generator may be provided between the master oscillator and the first tone generator, a second switching device being interposed between the third and first tone generators which is capable of connecting the input of the first tone generator selectively to any one of the outputs of the third tone generator.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG 1 is a block-schematic diagram of a circuit arrangement for transposing by means of separate octave dividers,

FIG. 2 is a block-schematic diagram of a similar circuit which includes a tone generator consisting of separate frequency converters,

FIG. 3 is a block-schematic diagram of a circuit for forming chords,

FIG. 4 is a schematic diagram of the circuit of FIG. 3 having one contact for each key,

FIG. 5 shows a gate circuit which includes diodes,

FIG. 6 shows a matrix for four types of chords, and

FIG. 7 is a block schematic diagram of a circuit of the kind shown in FIG. 3 provided with a transposition facility.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, a master oscillator O is connected to the input of a tone generator T ₁ which has twelve outputs from which the tones of one octave can be derived. Each of the twelve outputs are connected to a separate contact C ₁ to C ₁₂ , respectively of a switching device S ₁ . A wiper L ₁ of this switch can contact any one of the contacts C ₁ to C ₁₂ . The end of the wiper is connected to the input of a second tone generator T ₂ which consists of a multiple frequency converter FC ₁ delivering twelve tones of one octave at twelve outputs. The twelve outputs of the frequency converter FC ₁ are each connected to an octave divider OD ₁ to OD ₁₂ respectively which each have a plurality of outputs for delivering tones, the pitches of which differ by one octave from one another. If, for example, the tone which is produced at the first output of the first tone generator T ₁ , and which is derived from the contact C ₁ is a C, at the outputs of the octave divider OD ₁ octave tones of this C will be produced. At the outputs of the octave divider OD ₂ tones will be produced which are octave tones of C sharp, and so on. If the wiper L ₁ of the switching device S ₁ is set to the contact C ₂ , at which a tone is produced which has the pitch of C sharp, at the outputs of the octave divider OD ₁ octave tones of C sharp will be produced, at the outputs of the octave divider OD ₂ octave tones of D, and so on. As will be seen, all the outputs of the octave dividers OD ₁ to OD ₁₂ have been transposed by one semitone. Thus by setting the wiper L ₁ to one of the remaining contacts of the switching device S ₁ transposition can at will be performed over the entire octave.

FIG. 2 shows a circuit arrangement which in broad outline is equavilant to that of FIG. 1 with the difference, however, that the tone generator T ₂ comprises a series arrangement of frequency converters FC ₁ to FC ₁₂ which each at a first output U ₁ to U ₁₁ respectively deliver a tone which is lower by a semitone than the tone which is applied to the input I ₁ to I ₁₂ respectively. The frequency converters FC ₁ to FC ₁₂ may comprise, for example, a series of dividers-by-two which, via gate circuits, produce the tones at the first outputs U ₁ to U ₁₁ respectively, while a further output of the said dividers-by-two provide the musically suitable octave tones of the tones applied to their inputs.

In the circuit arrangement shown in FIG. 3 the signal from the output of the master oscillator O is again applied to the input of a tone generator T ₁ , which at its twelve outputs delivers the tones of an octave. The tones at the twelve outputs of the tone generator T ₁ are each applied to an octave divider OD ₁ ' to OD ₁₂ ' respectively. Tones serving to play the melody can be derived from dividers OD ₁ ' to OD ₁₂ '. For producing the chords, as is effected inter alia at the base side of accordions, each button K of the base side is connected to a double-pole switch S ₃ , S ₄ . For the sake of simplicity, in FIG. 3, the bass fundamental tone buttons have been omitted. In FIG. 3 the buttons in the conventional sequence according to the circle of fifths are shown in the horizontal direction, and the chord symbols generally used in music notation are shown in the vertical direction, M designating the major chord, m the minor chord, 7 the dominant seventh chord and dim the diminished seventh chord. For each tone the inputs of the switches S ₃ are connected in common to one another, and to that output of the tone generator T ₁ which is associated with said tone. The outputs of all the switches S ₃ are connected in common to one another and to the input of the second tone generator T ₂ . The inputs of the switches S ₄ are all connected in common to one another and to a voltage source. For each separate chord the outputs of the switches S ₄ are connected in common and to that first input I ₂₀ to I ₂₃ respectively of a matrix Ma which is associated with the relevant chord. The output signals of the second tone generator T ₂ which are required for producing the types of chords each are applied to an octave divider, an output of which is connected to a second input I ₃₀ to I ₃₆ respectively of the matrix Ma. The desired chords then can be derived from outputs U _M , U _m , U ₇ and U _dim of the matrix Ma. If more than one octave tone of the same pitch is to be sounded by pressing one button, the octave divider outputs associated with these tones are connected via an adder circuit to the inputs I ₃₀ to I ₃₆ of the matrix Ma.

Obviously, the tone generator T ₂ provided with the octave dividers may be replaced by a tone generator provided with twelve frequency converters FC ₁ to FC ₁₂ of the kind described with reference to FIG. 2.

FIG. 4 shows a circuit arrangement similar to that of FIG. 3 in which the double-pole switches S ₃ S ₄ are replaced by single-pole switches S. In this circuit arrangement all the incoming contacts are connected to a voltage source which delivers a voltage required for controlling the matrix used. With respect to the types of chords, the outgoing contacts are connected in common to one another via resistors R ₁ to R ₁₂ for the major chord M and to the major-chord input I ₂₀ of the matrix Ma, for the minor chord they are similarly connected via resistors R ₂₁ to R ₂₂ to the minor-chord input I ₂₁ of the matrix Ma, for the dominant seventh chord they are similarly connected via resistors R ₄₁ to R ₅₂ to the dominant-seventh-chord input I ₂₁ of the matrix Ma, and for the diminished seventh chord via resistors R ₆₁ to R ₇₂ to the input I ₂₃ of the matrix Ma. Diodes may be substituted for the resistors, in which case each input is connected to a voltage source via a resistor in the manner commonly used for gate circuits. On the other hand, the outputs of the switches associated with the chord of the same tone are connected in common each via a resistor R ₈₁ to R ₁₅₂ respectively to the associated output of the tone generator T ₁ via a diode D ₂₁ to D ₃₂ respectiveley. Each junction point of a diode D ₂₁ to D ₃₂ and the output of the respective resistor R ₈₁ to R ₁₅₂ respectively associated with the chord of the relevant tone is connected via a diode D ₄₁ to D ₅₂ respectively, which diodes together form an OR gate having twelve inputs, to the input of the second tone generator T ₂ , while in the usual manner the outputs of the diodes D ₄₁ to D ₅₂ are connected via a resistor R to a voltage source of a polarity and voltage such that when one of the buttons is pressed the tones of the other buttons are not allowed to pass. This provides the advantage that the input contact of the switches S may be a conductive sheet, or an insulating sheet coated with a conductive layer, which extends beneath all the contacts. For the remainder of the circuit arrangement we refer to the description of the circuit arrangement of FIG. 3.

FIG. 5 shows a method of forming the various chords by means of gate circuits. In FIG. 5a the output from the octave divider OD ₁ shown in FIGS. 3 and 4, that from the octave divider OD ₅ , which produces a tone which is the major third of the tone at the output of the octave divider OD ₁ , and the output from the octave divider OD ₈ , which produces a tone which is the fifth of the tone at the output of the octave OD ₁ , are applied through diodes D ₁ , D ₂ and D ₃ respectively to an output M at which the major chord is available. Similarly, in FIG. 5b to produce the minor chord the root, the minor third and the fifth, which are derived from the octave dividers OD ₁ , OD ₄ and OD ₈ , are applied to the diodes D ₄ , D ₅ and D ₆ respectively, the minor chord being available at the output m (FIG. 5b).

FIG. 5c shows how the dominant seventh chord is formed by deriving from the octave dividers OD ₁ , OD ₅ , OD ₈ and O ₁₁ the root, the major third, the fifth and the seventh respectively and applying them to the diodes D ₇ , D ₈ , D ₉ and D ₁₀ respectively, the dominant sevent chord being available at the output 7 of the gate circuit.

FIG. 5d shows the root, the minor third, the diminished fifth and the sixth being taken from the octave dividers OD ₁ , OD ₄ , OD ₇ and OD ₁₀ respectively and being applied via the diodes D ₁₁ to D ₁₄ respectively to be combined to form the diminished seventh chord at the output dim. In the above gate circuits the resistors R ₁ to R ₄ respectively ensure that the diodes D ₁ to D ₁₄ become selectively conductive and hence the gates are opened when a negative voltage is applied to the inputs of the resistors from the voltage source to which all the incoming contacts of the switch S ₄ of FIG. 3 are connected. For the circuit arrangement of FIG. 4 the said resistors are replaced by the resistors R ₁ to R ₁₂ , R ₂₁ to R ₃₂ , R ₄₁ to R ₅₂ and R ₆₁ to R ₇₂ , respectively.

FIG. 6 shows a matrix for four types of chords which comprise diodes. Inputs 1 to 7 are connected to the octave dividers OD ₁ , OD ₄ , OD ₅ , OD ₇ , OD ₈ , OD ₁₀ and OD ₁₁ respectively required to form the major, minor, dominant seventh and diminished seventh chords. The tone applied to the input 1 is the root G, that applied to the input 2 the minor third thereof, that applied to the input 3 the major third, that applied to the input 4 the lowered fifth, that applied to the input 5 the fifth, that applied to the input 6 the sixth and that applied to the input 7 the seventh of the root. If now a negative voltage is applied to the resistor R ₁ , the diodes D ₁ , D ₂ and D ₃ will become conductive and the tones associated with the inputs 1, 3 and 5, that is to say the root, the major third and the fifth, will be applied to the output M so that at the output M the major - third chord is produced. If a negative voltage is applied to the resistor R ₂ , the diodes D ₄ , D ₅ and D ₆ will become conductive so that the root, the minor third and the fifth appear at the output m, which together form the minor chord. If a negative voltage is applied to the resistor R ₃ , the diodes D ₇ , D ₈ , D ₉ and D ₁₀ become conductive, so that the root, the major third, the fifth and the seventh are applied to the output 7, which together form the dominant-seventh chord. Similarly, if a negative voltage is applied to the resistor R ₄ so that the diodes D ₁₁ , D ₁₂ , D ₁₃ and D ₁₄ become conductive, the root, the minor third, the diminished fifth and the sixth, which together form a diminished-seventh chord, appear at the output dim.

FIG. 7 shows a possible method of incorporating a transposition facility in a circuit arrangement as shown in FIG. 3 and FIG. 4 also. For this purpose there is interposed between the master oscillator O and the first generator T1 a third tone generator T ₃ , a second switching device S ₂ being interposed between the third tone generator T ₃ and the first tone generator T ₁ . A wiper L ₂ of the switch S ₂ at one end can be connected to any one of contacts C ₁ to C ₁₂ , the other end being connected to the input of the first tone generator T ₁ . The remainder of the circuit arrangement is similar to that shown in FIG. 3 or 4.