Patent GB-1384783-A (GB)
Title: Orchestral effect producing system for an electronic musical instrument
IPC: G10H1/10
Filed: 1972-04-14
Abstract: 1384783 Electronic musical instruments NIPPON GAKKI SEIZO KK 14 April 1972 [14 April 1971 2 July 1971] 17456/72 Heading G5J An electronic musical instrument includes a plurality of tone generators, which are connected to a reproducer, selectively and possibly simultaneously, in accordance with the keys which have been depressed on a keyboard, so that the each tone so selected passes through one of a plurality of tone colouring filters each one of which filters being connected in the path corresponding to each tone having a predetermined or selected position relative to the remaining tones selected from the tone generators by the depressed keys. In one embodiment as shown in Fig. 1, an upper right-hand keyboard 11 for melody performance, a lower left hand keyboard 12 for chord performance, and a left foot operated pedal keyboard 13 for bass performance, are provided to control tone signals for the tone generators 14 by means of keyers 15, 16 and 18. Tone signals keyed by keyers 15 and 18 are fed into tone colouring filters 19, 20 and the second keyer 16 delivers from the tone generators 14 tone signals corresponding to the simultaneously operated keys of keyboard 12 to a maximum of four notes. Keyer 16 comprises an array of ganged switches, Figs. 2A, 2B or 2C (not shown), each operated by a key on keyboard 12, and such that in each embodiment, conductors 21A, 21B, 21C, 21D are connected in ascending or descending order or otherwise depending on the switch arrangement, to the tone signals from tone generator 14 as selected. Tone colour selector 22 is connected to conductors 21A to 21D and may either comprise of switch selectable means for choice of which tone colour filter 23A-23D to be connected to which output conductor 21A to 21D, Fig. 3A (not shown), or as in Fig. 3B (not shown), where the output conductors are divided into two pairs, 21A-21B and 21C-21D. Between each pair, two potentiometers in reverse parallel to each other, are connected such that the slidable arms are connected each to one of the tone colouring filters, 23A to 23D, the frequency characteristic of which may be altered by a variable impedance (50A)-(50D) (not shown), and the level of which may be altered by variable resistors 24A to 24D. The tone signals from the tone colouring filters 19, 23A-23D, 20, are mixed a potentiometer 25, and a level control 28 is provided to control the volume at the reproducing means 29, 30, by a right foot pedal control 31. In another embodiment Fig. 7, a chord detector 52 and gating means 54A1, 54B1, &c., are provided to produce at the output conductors 21A to 21D of the second keyer 16 tone signals in accordance with notes constituting a chord played on the second keyboard 12. Chord detector 52 consists of diode connected matrices 54A, 54B, 54C, (see Fig. 6, not shown), matrix 54A being provided with outputs generated on detection of the root and fifth notes of a chord, matrix 54B generating a second output on detection of a major or minor third note and matrix 54C generating an output on detection of a minor seventh or major sixth note. These outputs are used, Fig. 7, to gate the relevant tones from the tone generators to the respective tone filters 23A-23D. In a further embodiment (Fig. 8, not shown), the selector means comprises a key controlled variable voltage source for producing voltages to control the frequency of notes generated by individual voltage controlled oscillators (64A-64D) which are in turn coupled to the audio channel through corresponding tone colouring filters (23).