US3789723A

US3789723A - Group training system for electronic musical instruments

Info

Publication number: US3789723A
Application number: US00278823A
Authority: US
Inventors: E Okamoto
Original assignee: Nippon Gakki Co Ltd
Current assignee: Nippon Gakki Co Ltd
Priority date: 1971-08-09
Filing date: 1972-08-08
Publication date: 1974-02-05
Anticipated expiration: 1991-02-05

Abstract

A group training system for electronic musical instruments including a teacher station and a plurality of student keyboard instrument stations wherein the teacher station has a plurality of tone generators corresponding to one octave of musical notes. Each tone generator is connected to a first divider chain including a plurality of cascade connected frequency dividers. The outputs of the tone generator and the frequency dividers are selectively supplied through a multithrow switch operable by the teacher to a second divider chain similarly including a plurality of cascade connected frequency dividers. The signals successively frequency-divided by the dividers of the second chain, as well as the input signal thereto, are all fed to each student station to provide a certain range of musical notes. Where the teacher operates the multithrow switch, the frequency of the input signal impressed on the second divider chain varies, resulting in a change in the performance compass of the student stations. The input signals impressed on the second divider chain may be varied for groups of the student stations to enable ensemble performance.

Description

United States Patent 1191 Okamoto Feb.5,1i974 [75] Inventor: Eisaku Okamoto, Hamakita, Japan [73] Assignee: Nippon Gakki Seizo Kabushiki Kaisha, Shizuoka-ken, Japan 22 Filed: Aug. 8, 1972 [21 App]. No.: 278,823

[30] Foreign Application Priority Data Primary Examiner-Lawrence R. Franklin Attorney, Agent, or Firm -Kemon, Palmer & Estabrook [57 I ABSTRACT A group training system for electronic musical instru ments including a teacher station and a plurality 01' student keyboard instrument stations wherein the teacher station has a plurality of tone generators corresponding to one octave of musical notes. Each tone generator is connectedto a first divider chain includ ing a plurality of cascade connected frequency dividers. The outputs of the tone generator and the frequency dividers are selectively supplied through a multithrow switch operable by the teacher to'a second divider chain similarly including a plurality of cascade connected frequency dividers. The signals successively frequency-divided by the dividers of the second chain, as well as the input signal thereto, are all fed to each student station to provide a certain range of musical notes. Where the teacher operates the multithrow switch, the frequency of the input signal impressed on the second divider chain varies, resulting in a change in the performance compass of the student stations. The input signals impressed on the second divider chain may be varied for groups of the student stations to enable ensemble performance.

11 Claims, 7 Drawing Figures Aug. 9, 1971 Japan 46/70440 Mar. 21, 1972 Japan 47/3230] Mar. 21, 1972 Japan 47/32302 [52] US. Cl. 84/470 [51] Int. Cl. G09b 15/00 [58] Field of Search 84/445, 454, 470, 477-482 [5 6] References Cited UNITED STATES PATENTS 3,470,785 10/1969 Shallenberger et a]. 84/470 2,924,776 2/1960 Peterson 84/454 X 3,482,480 12/1969 Decker 84/478 3,501,850 3/1970 Oachterlony 84/478 3,584,530 6/1971 Andersen 84/470 3,674,907 7/1972 Derry 84/445 X FREQUENCY 12 DlVJlgER TEACHER STATION 1 TO OTHER STUDENT STATION g PATENTEUFEB 51974 3.789.723

SHEEI 1 0f 4 TONE GENERATORS H c cg FREQUENCY DIVIDER HIGH TEAcHER MIDD STATION I TO OTHER STUDENT STATION KEY SWITCH STUDENT STATION 2 TONE GEN.

C? F I G. 2

I2 HIGH I4-/ .9 MI' DI \f I [LOVE +2 +2 +2 D TO FIRST GROUP 13-/Z2 A E OF STUDENT STATIONS I c TO SECOND GROUP B A f 20 3 +2 +2 +2 D I g TO THIRD GROUP I4-n I -2 -2 -2 TO n- Th GROUP PATENIEDFEB 5 m4 SHEET 3 0F 4 IFIG.4

DIVIDER CHAIN DIVIDER CHAIN DIVIDER CHAIN ?ATENTEBFB sum SHEET l BF 4 FIG.5

CABLES STUDENT STATION TEACHER STATION 2. i

FIG.6

IFIG.7

CABLES STUDENT STATION 2 N w T A T S E H C A E T TO OTHER STUDENT STATIONS GROUP TRAINING SYSTEM FOR ELECTRONIC MUSICAL INSTRUMENTS BACKGROUND OF THE INVENTION ,a group training system for keyboard musical instruments, particularly electonic organs. This system includes as many as 20 to 30 student stations formed of musical instruments as against a single teacher station. The students practice performance on their musical instruments under the teachersinstructions. Though student stations may consist of a type .having'tone generators of its own, there occur considerable difficulties in attaining agreement among the pitches of the same categories of tones obtained from the electronic musical instruments of the teacher and students.

In the group training system for muscial instruments, therefore, tone generators are all provided in the teacher station alone, and tone signals from the tone generators are distributed to the student stations. The

tone signals supplied to the student stations are conducted upon key depression by the students through key switches to the electronic circuits, for example, tone coloring filters and amplifiers of the student stations finally to operate the loudspeakers or headphones. Installation of tone generators only in the teacher station attains complete accord among the pitches of the same categories of tones produced-by all the musical instruments installed in the class room, and moreover prominently simplifies the musical instruments played by the students.

However, more transmission of tone signals from the teacher station to the student stations always gives forth the tones having-the identical pitch when the identical keys of the studentstations are depressed. Where, therefore, there is to be played an ensemble performance by dividing the student stations into same I groups and causing the groups to undertake performances of the high, medium and. low pitches respectively, then the teacher should inform the students of each group of that portion of the keyboard which they are requested to operate.

Musical instruments generally used for group training consist of a small type bearing, for example 49 keys. Such a small musical instrument has a narrow compass of tones and is undesirable for an ensemble performance, imposing limitations on a group training system for musical instruments.

It is accordingly an object of this invention to provide a group training system or musical instruments which enables the teacher freely to vary the compass of the student stations and consequently an ensemble performance to be attained even when the students operate the same part of the keyboards of their musical instruments.

Another object of the invention is to provide a device by which each'student is informed of the compass of tones with which he is making a performance.

SUMMARY OF THE INVENTION A teacher station used in a group training system for electronic musical instruments according to this invention is provided, like an-ordinary electronic musical instrument, with tone generators corresponding to 12 notes included in the high octave.

Each tone generator is connected to a plurality of frequency dividers arranged, for example, in two-stage cascade formation. Outputs from the tone generators and frequency dividers selectively pass through multithrow 'switches to divider chains each consisting of a plurality of cascade connected frequency dividers. All the above-mentioned frequency dividers divide the frequency of input signals by two. Outputs from the frequency dividers included in said divider chains are conducted to the student stations by cables so as to be used as octavelly related tone signals for the same note of the student stations. The aforesaid multithrow switch is changed by the teacher according as he chooses student stations to have a high, medium or low compass. Thus, even when the students operate the identical part of the keyboards of their musical instruments, the resultant tones will have the pitches varied to the high, medium or low level.

Further, according to this invention, there are provided lamps at such spots easily observed by the students that are close to the keys of the keyboards of the student stations corresponding to a referential note, for example, the note C For a 49-key musical instrument, three lamps will fully serve the purpose. Upon operation of the multithrow switch by the teacher, one of the lamps is turned on. For example, where the teacher chooses the high compass, a lamp on the extreme left, that is, the one positioned at the lower pitch side is operated to inform the students that their musical instruments are used for a high compass performance. Conversely where the teacher desires the students to make a low compass performance, then there is lighted a lamp on the extreme right, that is, the one disposed on the higher pitch side. To this. end, the three, lamps of each student station are connected to a power source through four lines and a switch provided in the teacher station which is interlocked with the aforesaid multithrow switch. Or if there is used an electronic circuit of the present invention, it will be possible selectively to turn on any one of the three lamps by connecting the teacher station and student stations using a pair of lines.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a group training system for electronic musical instruments according to an embodiment of this invention;

FIG. 2 is a block diagram of the tone generator and frequency divider arrangement of the teacher station where it is used for an ensemble performance on the student stations;

FIG. 3 is a block diagram of the tone generator and frequency divider arrangement of the teacher station attaining a better ensemble performance than that of FIG. 2;

FIG. 4 is a block diagram of a switching mechanism employed in the system of this invention;

FIG.'5 is aschematic plan view of a student station provided with lamps for indicating the variation of compasses;

3 FIG. 6 represents a connection diagram according to an embodiment of this invention for indicating the variation of student station compass; and

FIG. 7 shows a circuit diagram according to another embodiment of this invention for indicating the variation of student station compass.

DESCRIPTION OF THE PREFERRRED EMBODIMENTS As illustrated in FIG. 1, a teacher station 1, like an ordinary electronic musical instrument, has 12 tone generators corresponding to l2 notes included in the highest octave, for example, notes C C fi, D7, D E, F7, F 5, G1, CW7, A A and B The reference numeral 11 denotes one of the tone generators which produces tone signals corresponding to note C An output from the tone generator 1 1 is supplied to the input side of a first divider chain consisting of cascade connected

frequency dividers

12 and 13. Outputs from the tone generator 11, and

frequency dividers

12 and 13 are conducted to the three fixed contacts a, b and c respectively of a triple throw switch 14. The frequency dividers 12 and- 13 divide the frequency of input signals by two. Accordingly, there are obtained tone signals corresponding to the notes C C and C on the output sides of the' tone generator 11, and

frequency dividers

12 and 13.

The movable contact of the triple throw switch 14 is connected to the input side of a divider chain 20 consisting of three cascade connected frequency dividers l5, l6 and 17. From the movable contact of the triple throw switch 14 as well as from the output sides of the

frequency dividers

15, 16 and -17, there are drawn out octavelly related outputs A, B, C and D associated with the note C. These outputs and similar four octavelly related outputs associated with the other tone generators are supplied to the student stations 2 by cable. Tone signals from the teacher station 1 are conducted throughthe corresponding key switches to the electronic circuits of the student stations 2, for example, tone coloring filters and amplifiers.

Generation, as shown in FIG. 1, of four octavelly related tone signals for each note by the frequency dividarranged as illustrated in FIG. 4. Namely, each switching means connected to the divider chain 20 consists of two series-connected

double throw switches

40A and 40B controlled by

relays

41A and 41B respectively. One fixed contact of the first switch 40A is connected to the output terminal of the tone generator 11 and the other fixed contact of the switch 40A is connected to the output terminal of the frequency divider 12. The movable contact of the first swtich 40A is connected to one fixed contact of the second switch 40B, the other fixed contact of which is connected to the output terminal of the frequency divider 13, and the movable contact of which is connected to the divider chain 20. Double throw switches associated with other tone generators representing the notes C to B are connected in the same manner. The coils of the

aforesaid ers

15, 16 and. 17 corresponds to the case where the student stations each consist of a 49-key electronic musical instrument.

Where the teacher operates the triple throw switch 14 to connect the movable contact to the fixed contact a, there are obtained four output tone signals A,.B, C and D corresponding to the notes C C C and C, respectively. Namely, the student stations are set to have a relatively high compass as C, to C Where the teacher operates the triple throw switch 14 to connect the movable contact to the fixed contact b, then the student stations make a performance with a relatively medium compass asC to C And where the movable contact is connected to the fixed contact c, then the student stations make a performance with a relatively low compass as C to C The teacher station has 12 triple throw switches 14 to match all the notesC, through 8,. It is preferred for simplification of the teachers operation that the 12 triple throw switches 14 be designed to interlock each other as shown in FIG. 1.

Twelve interlocking triple throw switches, however, will have an extremely complicated construction. Therefore, it is desired that the interlocking switches be

relays

41A and 41B are connected at one end to the movable contact of the triple throw switch 14 through a power source 42, and at the other end to the fixed contacts b and c, respectively, of the triple throw switch 14. Another fixed contact switch a of the triple throw switch 14 remains empty. The condition where the

double throw switches

40A and 40B are in the indicated position denotes that where the

relays

41A and 41B are not energized, namely, where the movable contact of the triple throw switch 14 contacts its empty fixed contact a.- Since, at this time, an output from each tone generator is directly supplied to the corresponding divider chain, the student stations are set to make a high compass performance. Where the movable contact of the triple throw switch 14 is made by the teachers operation to contact the fixed contact b connected to the relay 41A for its energization, then the movable contact of the firstdo'uble' throw switch 40A changes its engagement from one fixed contact to the other. Under this condition, the student stations make a medium compass performance. Where the movable contact of the triple throw switch 14 contacts still another fixed contact c to energize the relay 413, then the movable contact of the second double throw switch 40B changes its engagement from one fixed contact to the other, causing the student stations to play a low compass'performance.

' According to the tone generator arrangement shown in FIGS. 1 and 4, operation of thetriple throw switch 14 provided in the teacher station causes all the student stations to make a performance with the same compass, thus presenting difficulties 'in effecting an ensemble performance on the student stations. FIG. 2 indicates the arrangement whereby the student stations can attain an ensemble performance even when the students operate the same part of the keyboard. In a group training system according to the embodiment of FIG. 2, student stations are divided into' a plurality of groups. There are provided divider chains 20-1 to 20-n each arranged like that of FIG. 1 in the same number as the groups of student stations. As in the embodiment of 4 Where the triple throw switches 14-1 to l4-n are in the indicated state, the student stations of the first and second groups are set to makea high compass performance, the third group to play a medium compass performance and the group of the n-th order to produce a low compass performance. Accordingly, the arrangement of FIG. 2 enables the various groups of student stations to play performances with different compasses, that is, an ensemble performance collectively while all the students operate the identical part of the keyboards.

The embodiment of FIG. 3 has an arrangement capable of displaying a better ensemble performance. According to this embodiment, the divider chains -1 to 20-n for the tone generator corresponding to the note C are selectively supplied with tone signals corresponding to the G notes as shown or alternatively E notes displaced or transposed five or three degrees from the C notes so as to have good musical agreements with the C notes. Thus the divider chains 20-1 to 20'-n are selectively supplied with outputs from the frequency dividers 24 and 25 associated with the tone generator 23 of the note G (or E included in the teacher station and outputs from the frequency dividers l2 and 13 associated with the tone generator 11 of the tone C The other tone generators 11 are likewise as sociated with the tone generators 23 whose pitches are five or three degrees displaced from those of the for met. The embodiment of FIG. 3 also includes series connected double throw switches 26 and 27. The first double throw switch 26 is used to choose the pitch of tone signals from the tone generator 11 and the second swtich 27 to choose the note of tone signals from either of the

tone generators

11 and 23, that is, tone signals representing either the C or G notes. Where the double throw switches 26 and 27 are in the indicated state, the divider chain 20-1 is supplied with a note C tone signal from the frequency divider 12, the divider chain 20-2 with a note C tone signal from the frequency divider 13, the divider chain 20-3 with a note G tone signal from the frequency divider 25 and thedivider chain 20-n with the same tone signal as that supplied to the divider chain 20-1. In this case, therefore, the third group of student stations can make a performance whose pitch is displaced or disposed five'degrees from that played by the other groups, through the students of the third group depress the same part of the keyboard as that operated by the students of the other groups. 1

In the case of the aforesaid embodiments, the students have to recognize by their auditory sense the compasses played by themselves, when the teacher varies the compasses played by the students. However, it is difficult for'the students to discriminate thecompasses with which they are making a performance. Accordingly, it will be more desirable if the students can visually judge which of the high, medium and low compasses is adopted for the performance played by. themselves.

To this end, the group training system of this invention includes a plurality of indicators or lamps disposed adjacent to the keyboard of each student station. One of the lamps is turned on in accordance with teachers operation to change the compass of the student stations, thereby assisting the students in distinguishing the compass with which they are making a performance.

6 FIG. 5 is a plan view of an electronic musical instrument constitutinga student station. Where the student station consists of a four-octave or 49-key electronic musical instrument, there are fitted three

lamps

52, 53 and 54 to a bar 51' disposed adjacently to the keyboard 50. These lamps are spaced at an interval correspond ing to one octave. The

keys

55, 56 and 57 facing the lamps denote particular notes, in this case, C notes. The key facing a lighted lamp further represents a reference note C Where the teacher operates to change the compass of the performance on the student stations to a high level, the lamp 52 on the extreme left alone is turned on. Since the key 55 facing the lamp 52 denotes the note C the students can recognize that they are playing a performance with a high compass. In the case of this high compass performance the

keys

56 and 57 correspond to the notes C and C, respectively. Where there is played a performance with a medium compass, the lamp 53 alone is operated. From the fact that the key 56 facing the lamp 53 corresponds to the note C the students are informed that they are playing a performance with a medium compass. In the case of a low compass performance, the lamp 54 on the extreme right alone is lighted, indicating that the student stationsare making a low compass performance. The foregoing description is based on the fact that an output A from the triple throw switch 14 of FIG 1, outputs B and C from the

frequency dividers

15 and 16 respectively are supplied to key switches actuated by the

keys

57, 56 and 55 facing the

aforesaid lamps

54, 53 and 52.

FIG. 6 illustrates a circuit for selectively turning on any oneof the three

lamps

52, 53 and 54. The teacher station 1 further includes another triple throw switch 60 for lamp indication interlocking the aforesaid triple throw switch 14 anda power source 61. The three fixed contacts of the lamp indication triple throw switch 60 are connected by cable to one end of the

lamps

52, 53

1 and 54 and the movable contact of the swtich 60 is connected similarly by cable to the other ends of the lamps through the power source-61 The lamp indication circuit of FIG. 6 requires the same number of cables as the lamps for each student station 2. Where, therefore, there are provided many student stations, the work of connecting the cables will be accompanied with great difficulties.

FIG. 7 shows a lamp indication circuit free from the drawbacks of the circuit of FIG. 6. According to the embodiment of FIG. 7, there is connected in parallel with a power source 62 of the teacher station 1 a triple throw switch 60 for lamp indication interlocking the aforesaid triple throw switch 14. The fixed contact a of the lamp indication switch 60 is connected to the positive terminal of the power source 62 and the fixed terminal c is connected to the negative terminal thereof,

namely, to the ground, whereas the fixed contact b of the switch 60 remains idle. The positive terminal of the power source 62 and the movable contact of the'lamp indication switch 60 are connected. by cable to the student stations 2. t

In the student stations, there are connected in series between the power source positive terminal line 63 and ground the collector-emitter circuit of an NPN transistor Tr, and that of a PNP transistor Tr with the emitters connected with each other, the bases of which are connected to the movable contact line 64 of the lamp indication switch 60.

To the emitters of the transistors Trl and'Tr2 is connected a first control means 65 including PNP transistors Tr and Tr,,. The base of the transistor Tr is connected to the emitter of the transistor Tr and the base of the transistor Tr., to the collector of the transistor Tr The collector-emitter circuits of the transistors Tr' and Tr, are connected between the positive terminal line 63 and ground. To the collector circuit of the transistor Tr is connected a first indicator or lamp 52.

The collector-emitter circuits of a PNP transistor Tr and an NPN transistor Tr constituting a second control means 66 are connected inseries between the positive terminal line 63 and ground. A second indicator or lamp 53 is connected between the collectors of the transistors Tr, and Tr,,. The bases of both transistors Tr and Tn, are connected to the emitter of the transistor Tr The collector-emitter circuits of NPN transistors Tr, and Tr constituting a third control means 67 are connected between the positive terminal line 63 and ground. The base of the transistor Tr, is connected to the emitter of the transistor Tr and the base of the transistor Tr to the collector of the transistor Tr,. A third indicator or lamp 54 is connected to the collector of the transistor Tr Where, in the circuit of FIG. 7, the movable contact of the lamp indication switch 60 is connected, as shown, to the fixed contact a, the transistor Tr, is turned on and the transistor Tr, is turned off. Under this condition, the transistor Tr, included inthe first control means 65 is rendered nonconductive and the transistor Tr, included therein is rendered conductive. The'transistors Tr, and Tr of the second control means 66 are turned off andon respectively. The transistors Tr, and Tr, of the third control means 67 are turned on and off respectively. in this case, therefore, the first lamp 52 alone is obviously lighted.

Where the movable contact of the lamp indication switch 60 is connected to an idle fixed contact b, then the transistors T r,, Tr Tr and Tr, are rendered nonconductive and the transistors Tr Tr Tr and Tr, are rendered conductive. In this case, the second lamp 53 alone is lighted.

Where the movable contact of the lamp indication switch 60 contacts the fixed contact c, then the transistors Tr Tr Tr and Tr, are turned off and the transistors Tr Tr Tr, and Tr are turned on, thus operating the third lamp 54 alone. As apparent from the foregoing description, combinations of the different conductivity type transistors constituting the first to third control means enable any one of the three lamps to be selectively lighted. v

What is claimed is:

1. In a group training system for musical instruments including a single teacher station and a plurality of student stations formed of keyboard musical instruments comprising:

each of said student stations having a multi-octave keyboard with a key swtich for each key of said keyboard, and said teacher station comprising: a plurality of tone generators providing the tones of one octave of the chromatic scale; each of said tone generators having an output terminal connected to a first chain of cascaded frequency dividers, each of said frequency dividers having an output terminal;

8 swtiching means having a plurality of inputs connected, respectively, to each of said output terminals and having an output connected to a second chain of frequency dividers, said switching means operative to selectively connect one of said inputs to said output; 1 said second chain of frequency dividers comprising a plurality of cascaded frequency dividers whose outputs are connected to said key switches on said student keyboard corresponding to respective octaves of the tone of said each tone generator.

2. The group training system according to claim 1 wherein said frequency dividers constituting the first and second divider chains divide the frequency of input signals by two.

3. The group training system according to claim 1 wherein each of said student stations includes a plurality of indicators positioned adjacent to the. keyboard and a plurality of control means each provided with a control terminal and connected in series to said indicators across a power source; and said teacher station includes a second switching means interlocking said switching means between said first and second divider chains and having a movable contact and the same number of fixed contacts as said plural control means, said fixed contacts being so connected as to have different potentials and said movable contact being connected to the control terminal of each of said plural control means, thereby impressing a control potential on the control terminals of all said plural control means according to the condition of said switching means so as to give'and indication to-theindicators.

4. The group training system according to claim 1 wherein said teacher station further includes a plurality of second tone generators bearing a particular musical relationship with said first tone generators; and a third divider chain corresponding to one of said second tone generators and including a plurality of cascade connected frequency dividers and connected to said one of said second tone generators, the output "terminal of at least one frequency divider included in said third divider chain being connected to at least one of the inputs of the switching means.

5. The group training system according to claim 1 wherein each of said student stations includes a pluralityof indicators disposed adjacent to the keyboard; and

said teacher station includes a second switching means interlocking the switching means between said first-and second divider chains and selectively giving an indication to said indicators.

6. The group training system according to claim 5 wherein said second switching means is provided with a plurality of fixed contacts each connected to each of the indicators, and with a movable contact connected to the indicators through a power source.

7. The group training system according to claim 5 wherein said indicators are so disposed as to facethe keys on the keyboard corresponding to predetermined notes.

8. The group training system according to claim 5 wherein said student stations each include first, second and third indicators and first, second and third control means; and wherein said first control means includes first and second transistors of a first conductivity type which are so connected that while said first transistor is rendered conductive, said second transistor is rendered nonconductive by base bias voltages, the base of said first transistor being connected to said movable contact of said second switching means and the collector-emitter circuit of said second transistor being connected to said first indicator, said second control means includes third and fourth transistors of a second conductivity type different from said first conductivity type, said third and fourth transistors being so connected that while said third transistor is rendered conductive, said fourth transistor is rendered nonconductive by base bias voltages, the base of said third transistor being connected to said movable contact of said second switching means and the collector-emitter circuit of said fourth transistor being connected to said second indicator, and said third control means includes a fifth transistor of said first conductivity type and a sixth transistor of said second conductivity type, said fifth and sixth transistors having their collector-emitter circuits connected in series in the forward direction, the bases of fifth and sixth transistors being connected to said movable contact of said second switching'means and said third indicator being connected between the collector-emitter circuits of said fifth and sixth transistors.

9. The group training system according to claim 8 wherein said first conductivity type is an NPN type and said second conductivity type is a PNP type.

10. The group training system according to claim 8 which further comprises a seventh transistor of said first conductivity type and an eighth transistor of said second conductivity type, said seventh and eighth transistors having their collector-emitter circuits connected in series in the forward direction, said movable contact of said second switching means being connected to the bases of said seventh and eighth transistors, and electrodes of said seventh and eighth transistors connected to each other being connected to the bases of said first, third, fourth and fifth transistors included in said first, second and third control means.

11. In a group training system for musical instruments including a single teacher station and a plurality of groups of student stations formed of keyboard musical instruments comprising:

each of said student stations having a multi-octave keyboard with a key switch for each key of said keyboard, and

said teacher station comprising:

a plurality of tone generators providing the tones of one octave of the chromatic scale;

each of said tone generators having an output terminal connected to a first chain of cascaded frequency dividers, each of said frequency dividers having an output terminal;

a plurality of swtiching means, each of said switching means having a plurality of inputs connected, respectively, to each of said output terminals and having an-output connected to a second chain of frequency dividers, said switching means operative to selectively connect one of said inputs to said out P said second chain of frequency dividers comprising a plurality of cascaded frequency dividers whose outputs are connected to each respective group of said student stations to said key switches on said keyboard corresponding to respective octaves of the tone of said each tone generator.

Claims

1. In a group training system for musical instruments including a single teacher station and a plurality of student stations formed of keyboard musical instruments comprising: each of said student stations having a multi-octave keyboard with a key swtich for each key of said keyboard, and said teacher station comprising: a plurality of tone generators providing the tones of one octave of the chromatic scale; each of said tone generators having an output terminal connected to a first chain of cascaded frequency dividers, each of said frequency dividers having an output terminal; swtiching means having a plurality of inputs connected, respectively, to each of said output terminals and having an output connected to a second chain of frequency dividers, said switching means operative to selectively connect one of said inputs to said output; said second chain of frequency dividers comprising a plurality of cascaded frequency dividers whose outputs are connected to said key switches on said student keyboard corresponding to respective octaves of the tone of said each tone generator.

3. The group training system according to claim 1 wherein each of said student stations includes a plurality of indicators positioned adjacent to the keyboard and a plurality of control means each provided with a control terminal and connected in series to said indicators across a power source; and said teacher station includes a second switching means interlocking said switching means between said first and second divider chains and having a movable contact and the same number of fixed contacts as said plural control means, said fixed contacts being so connected as to have different potentials and said movable contact being connected to the control terminal of each of said plural control means, thereby impressing a controL potential on the control terminals of all said plural control means according to the condition of said switching means so as to give and indication to the indicators.

4. The group training system according to claim 1 wherein said teacher station further includes a plurality of second tone generators bearing a particular musical relationship with said first tone generators; and a third divider chain corresponding to one of said second tone generators and including a plurality of cascade connected frequency dividers and connected to said one of said second tone generators, the output terminal of at least one frequency divider included in said third divider chain being connected to at least one of the inputs of the switching means.

5. The group training system according to claim 1 wherein each of said student stations includes a plurality of indicators disposed adjacent to the keyboard; and said teacher station includes a second switching means interlocking the switching means between said first and second divider chains and selectively giving an indication to said indicators.

7. The group training system according to claim 5 wherein said indicators are so disposed as to face the keys on the keyboard corresponding to predetermined notes.

8. The group training system according to claim 5 wherein said student stations each include first, second and third indicators and first, second and third control means; and wherein said first control means includes first and second transistors of a first conductivity type which are so connected that while said first transistor is rendered conductive, said second transistor is rendered nonconductive by base bias voltages, the base of said first transistor being connected to said movable contact of said second switching means and the collector-emitter circuit of said second transistor being connected to said first indicator, said second control means includes third and fourth transistors of a second conductivity type different from said first conductivity type, said third and fourth transistors being so connected that while said third transistor is rendered conductive, said fourth transistor is rendered nonconductive by base bias voltages, the base of said third transistor being connected to said movable contact of said second switching means and the collector-emitter circuit of said fourth transistor being connected to said second indicator, and said third control means includes a fifth transistor of said first conductivity type and a sixth transistor of said second conductivity type, said fifth and sixth transistors having their collector-emitter circuits connected in series in the forward direction, the bases of fifth and sixth transistors being connected to said movable contact of said second switching means and said third indicator being connected between the collector-emitter circuits of said fifth and sixth transistors.

11. In a group training system for musical insTruments including a single teacher station and a plurality of groups of student stations formed of keyboard musical instruments comprising: each of said student stations having a multi-octave keyboard with a key switch for each key of said keyboard, and said teacher station comprising: a plurality of tone generators providing the tones of one octave of the chromatic scale; each of said tone generators having an output terminal connected to a first chain of cascaded frequency dividers, each of said frequency dividers having an output terminal; a plurality of swtiching means, each of said switching means having a plurality of inputs connected, respectively, to each of said output terminals and having an output connected to a second chain of frequency dividers, said switching means operative to selectively connect one of said inputs to said output; said second chain of frequency dividers comprising a plurality of cascaded frequency dividers whose outputs are connected to each respective group of said student stations to said key switches on said keyboard corresponding to respective octaves of the tone of said each tone generator.