US 3674907 A
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United States Patent [1 1 3,674,907 Derry 1 July 4, 1972 s41 KEYBOARD TRANSPOSITION 0F 3,030,848 4/1962 Wick ..s4 44s ELECTRICAL MUSICAL E L H M rlmary xammer ew|s yers INSTRUMENTS Assistant Examiner-U. Weldon  Inventor: Wendell A. Derry, 419 High Street, Ran- Attorney-Martin M. Santa dolph, Mass. 02368 21 App1.No.: 199,474  ABSTRACT The keyboard of musical instruments, such as electronic organs, is connected through frequency divider circuits to basic  US. Cl. ..84/ 1.01, 84/DlG. 7, 8% tone generators such that corresponding y of adjacent 51 I t Cl Gloh 1/00 taves produce notes which are separated by an octave and add 07 l 08 jacent keys produce the tonal scale. This invention discloses I l o i electronic switching which allows all keys to be moved up or down the tonal scale in unison by connecting different tone generators to the frequency divider networks according to the  References Clted key in which the music is to be provided while the music may UNITED STATES PATENTS pe plzttied on the keyboard from sheet music written in a diferen e 2,618,753 11/1952 Mierlo ..84/D1G, 23 y 3,023,659 3/1962 Bode 7 Claims, 2 Drawing Figures 5 1 eeeqweegmwwm c FGAB I with 1' 6 Du". a ||||1|1| llllllll lllllll flllll-lll [Hunt 25': loo Na i IHHI ||||l ||r|||r ||||n .uinrr n jL n V F 2'! F I! u w G d" i A A 'o" F. H F 3A H5 rllltllll ILLllLl Llllllll Illlllll I lglllllllll ,lll [I'l I l7 l3 I7 80 PL,
zrr- I- PA'TENTEDJUL 4 m2 SHEET 2 BF 2 KEYBOARD TRANSPOSITION OF ELECTRICAL MUSICAL INSTRUMENTS BACKGROUND OF THE INVENTION This invention relates to electronic musical instruments and more particularly to apparatus for use with keyboard instruments such as electronic organs which enables the player of the instrument to transpose music to different key signatures without necessitating an involved mental process for each note so that each digital (key), actuated in normal manner, may produce a musical sound from a tone generator that is selectively displaced a desired and similar amount from the note indicated by the musical score, for example. Musical compositions are usually written in a particular key signature but as it is often desired to play the instrument in conjunction with other instruments or to accompany people in singing, for example, the key indicated on the score may not be suitable in particular instances and therefore a transposition either to a higher key signature or to a lower key signature is necessary. While transposition from one octave to the next, either higher or lower, is comparatively easy, such octave transpositions are of too large a magnitude in most if not all cases and it is necessary to operate digitals (including adjustment for sharp and flats) that are displaced a uniform amount from the digitals indicated on the score. This is often and arduous task for even the professional to perform easily and accurately and often is impossible for the amateur to play so that the expected and desired satisfaction is obtained from the performance.
Accordingly, it is an object of this invention to provide a simple, inexpensive apparatus capable of easily and quickly producing key transposition so that music scored in any key can be played in that key while providing sound in any other key.
Two examples of prior art patents which have produced key transposition on electronic organs are those to Harald Bode, U.S. Pat. No. 3,023,659 and to Martin Wick, US. Pat. No. 3,030,848. The Wick patent describes a transposing switch which has a switch contact between every digital and the frequency generating circuits. Movement of the switch through one switch position effects a connection of a given frequency generating circuit to the next adjacent digital. Wicks switch allows these connections to be made with rotational or translational movement of connecting wires which ultimately could break the connection through flexure fatigue. The switch arrangement of Wicks involves considerable expense in wiring costs which increases to a considerable extent the cost of an organ so equipped.
The Bode patent discloses apparatus for transposing digitals by using twice the number of oscillator circuits than are found in the conventional electronic organ and connecting a contiguous group of these circuits, constituting an octave, through a complex switching circuit to the appropriate frequency dividers which in turn are connected to the digitals. It is apparent from the wiring diagram of the Bode patent that the complexity of the individual switches and the multitudinous connections to be made to these switches with wires to the oscillator circuits and the frequency dividers would make such a device for the digital transposition extremely expensive in relation to the cost of the electronic organ thereby greatly restricting its utility.
It is therefore a more specific object of this invention to provide a transposition apparatus which is an improvement over the device of Bode in the respect that only one simple switch with a relatively few wires connected thereto can accomplish the same result as that of Bode at much less expense.
Other objects and functions of this invention will be apparent upon consideration of the following detailed description of the invention in conjunction with the figures, wherein:
FIG. 1 is a schematic diagram of the transposition circuit.
FIG. 2 is a circuit diagram showing the switching network used in the circuit of FIG. 1.
2 SUMMARY or THE INVENTION Basic tone generators are provided in excess of the 12 normally found in an electronic organ. Electronic switching networks connect difierent groups of 12 tone generators to the frequency dividing networks of the organ. The particular group of 12 tone generators which is connected depends upon whether the switching network to which it is connected is energized by the voltage from a selector switch. A selected key of the keyboard will produce a note which depends upon the selector switch position. Thus, transposition is obtained over the entire keyboard by simply selecting a switch location of a rotary or push button switch.
FIG. 1 is an embodiment of the invention which provides transposition over a full octave if desired. Twenty-three basic tone generators 50, or oscillator circuits, C, C A, are shown in ascending order of the musical scale of notes over a consecutive two octave range less one note 8,. B, is one octave higher in frequency than the note B. By energizing one of the diode switching networks by selector switch 200 each generator of a group of 12 consecutive tone generators 50 may be connected to each of the twelve frequency divider networks 30, respectively, as in a conventional electronic organ. Each frequency divider network 30 is comprised of serially connected dividers 31, 32, 33 each of which produce at its output a fundamental frequency half that of its input fundamental frequency. Each frequency divider 31, 32, 33 has shown at its output a switch S31, S32, S33 respectively, which corresponds to the switch actuated by a particular key of the keyboard, each key being an octave apart. As an example, switch S30 may be considered to be the switch actuated by the highest C" key on the keyboard, switch 531 is actuated by the next lower C key, etc. When circuit 100 is energized, switch S30 is connected to the C oscillator 50' and the keys of the keyboard will all produce the notes normally associated with each key. Thus, switch S31 would correspond to the C in the next lower octave and would produce a note an octave lower than that produced by switch S30, and so on.
In a corresponding manner switch S30" would produce a note generated by generator C and so on. The switches S30, S30", S31 etc., are connected as in the conventional electronic organ to electronic circuitry for tone filtering and amplification before being applied to a loudspeaker.
As an example of the detailed operation of the circuit of FIG. 1 consider the situation where switch 200 movable contact arm 26 is at switch contact 29. A source of dc. voltage 35 is applied through contact 29 to the energization terminal 25 of diode switching network 100. In a manner to be explained subsequently, energization of terminal 25' causes a low impedance electrical connection between terminals 1 and 13, terminals 2 and 14, and terminals 12 and 24. Terminals l, 2, 12 of network 100 are connected to tone generators C, C B, respectively. Terminals l3, l4, 24 of network 100 are connected to corresponding by numbered terminals of frequency dividers 30, 30", 30" respectively, as indicated on FIG. 1. Therefore, when terminal 25 is energized, tone generator C is electrically connected to input terminal l3 of divider network 30', tone generator C is connected to input terminal 14 of network 30", and lastly tone generator B is connected to input terminal 24 of divider network 30. Thus when switching network 100' is energized, switch S30, assumed to be actuated by the "C" key of the highest octave of the keyboard, will produce a C note as in the conventional electronic organ.
If it is desired to transpose by one-half note higher the frequency produced by the C" key of the keyboard, switch arm 26 is moved to contact 28 which will cause source 35 to energize diode switching network 100" instead of network 100. Energization of network 100" causes its inputs from signal generators C D, C to be connected to the divider networks at their input tenninals 13, 14, 24, respectively. The C generator has a frequency one octave higher than the C generator. Thus switch $30 will, when closed by depressing the C key, produce a C note in the output loudspeaker, not shown. Also switch S30", closed by the C it key will produce a D note, switch 830" closed by the D" key will produce the C note, and so on. Thus, all keys on the keyboard will produce a frequency one-half note higher when selector switch 200 arm 26 is in position 28 than when it was in position 29.
This transposition process continues for all switch arm 26 positions up to and including the last contact 27 which causes switching network 100" to be energized. At this switch position the notes produced by the keyboard are transposed by the maximum amount, namely eleven half notes, so that the key which normally produces a C note on the conventional organ produces a 8 note in the same octave whereas the key which normally produces a B note will produce an A note.
The diode switching network 100 is shown in detail in FIG. 2. Terminal 25, to which a negative d.c. voltage 35 is applied when the network is energized, is connected to ground through resistor 42, diodes 40, 43 and resistors 41, 44. For the diode polarity shown in FIG. 2, the voltage 35 at terminal 25 should be negative with respect to ground to cause diodes 40, 43 to conduct. Each pair of conducting diodes 40, 43 provide a low impedance connection between terminal 1 and 13, 2 and 14, etc.
Since terminal 25 is common to all the signal paths within the switching network 100, it is necessary that the impedance to ground at terminal 25 be small in order to avoid cross coupling of signal paths. This low impedance may be obtained by a filter capacitor 34 connected across the d.c. source 35.
While the principles of the invention have been described above in connection with specific apparatus and applications, it is to be understood that this description is made only by way of example and not as a limitation on the scope of the invention.
What is claimed is:
1. Apparatus for transposing notes of a keyboard musical instrument comprising,
a plurality of basic tone generators arranged in sequence in the tonal scale,
said plurality of tone generators being greater than a selected number N,
a number of electronic switching networks, said number of networks being equal to the number of tone generators in excess of the selected number N,
each switching network having input and output terminals equal in number to said selected number N, each input terminal being connected to a different output terminal through an electronic switching means,
each input terminal of a switching network being connected to a different tone generator in a group of sequential tone generators,
a plurality of frequency divider networks equal in number to said outputs of a said switching network,
corresponding output terminals of each switching network being connected to a different divider network,
a source of electrical energy,
a selector switch whose input is connected to said source of energy,
said selector switch having a plurality of output terminals equal in number to the number of switching networks, only one temiinal being selectively energized by a selected switch position,
each switching network having an energizing terminal connected to a difierent output terminal of said selector switch, each said electronic switching means forms a low impedance connection between each input temlinal and the corresponding output temiinal when the energizing terminal of the network is energized by said source of energy and a high impedance when not energized,
whereby the selection of a switch position causes a specific cup of the selected number of basic tone generators to e connected to the frequency dividing networks through an energized switching network.
2. The apparatus of claim 1 wherein said switching network comprises,
a plurality of the said electronic switching means, each switching means connected between an input and a corresponding output of the network,
each switching means having a control terminal connected to the input terminal of the switching network.
3. The apparatus of claim 2 comprising in addition an electrical impedance inserted between each switching means control temtinal and the input terminal of the switching network.
4. The apparatus of claim 3 wherein said switching means comprises,
two serially connected diodes having their point of connection at the control terminal of the switching means,
the other ends of said diodes each being connected to ground by a resistor and each being the input and output tenninal of said switching network.
5. The apparatus of claim 3 comprising in addition a low electrical impedance connected between said selector switch input and ground.
6. The apparatus of claim wherein,
said selected number N is 12, corresponding to the number of notes in an octave.
7. The apparatus of claim 6 wherein,
said number of electronic switching networks is l 1, thereby allowing key transposition over an entire octave.