GB1592468A

GB1592468A - Apparatus for the wireless transmission of a teaching programme

Info

Publication number: GB1592468A
Application number: GB5196777A
Authority: GB
Original assignee: DEMOLUX VERWALTUNGS GmbH
Current assignee: DEMOLUX VERWALTUNGS GmbH
Priority date: 1976-12-14
Filing date: 1977-12-14
Publication date: 1981-07-08
Also published as: DE2656431A1; JPS53106229A

Description

(54) APPARATUS FOR THE WIRELESS TRANSMISSION OF A TEACHING PROGRAMME (71) We, DEMOLUX VERWALTUNG SGESELLSCHAFT MIT BESCHRÄNKTER HAF TUNG, a Body Corporate of the Federal Republic of Germany of Wiesenstrasse 3-5, 607-Langen, Federal Republic of Germany and the sole personally responsible partner of DEMOLUX GESELLSCHAFT MIT BESC HRÄNKTER HAFTUNG & Co, KOMMAN DITGESELLSCHAFT of Wiesenstrasse 3-5, 607-Langen, Federal Republic of Germany, do hereby declare this invention, for which - e pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to apparatus for the wireless transmission of a teaching programme from a teacher appliance to a plurality of pupil appliances.

Such devices for the transmission of a teaching programme in instruction rooms are known and are distributed under the title of "language laboratory". They require instruction rooms with a large number of special installations. For the teacher there is aranged a separate cubicle, which is frequently separated from the remainder of the instruction room by a glass wall. This necessitates a separation ,of pupil and teacher, which in many cases has proved very disadvantageous educationally, because it isolates the teacher from the pupils. If the pupil appliances are connected via cables to the teacher appliance, appropriate wiring of the entire room is necessary, the consequence of which is that not only quite considerable installation expenditure is necessary, but the tables in the room can no longer be moved to another location. The installation, which is practically permanent in spite of plug and socket connections, prevents the room being used for anything else and complicates such daily essentials as cleaning the room. A further disadvantage is the low flexibility, especially in "multimedia" instructions. The result of this lack of flexibility, or complexity, of the system is that language laboratories (which are very costly in regard to outlay in normal higher schools in which they are installed) are not used because actuating many technical teaching aids, in addition to his teaching activity, is too difficult for the teacher.

Experiments in producing wireless language laboratories in which transmission occurs by means of radio have led to almost insoluble problems. Only a few channels of the frequency spectrum are available for transmission. The installations are subject to approval. Good electrical insulation of the classrooms in which this device is installed is essential because, if two of more classrooms are provided with such installation, it is necessary to provide screening measures, so that signals which are radioed in one classroom do not have a disturbing effect in an adjacent room. Synchronization of the appliances used in a second room to another frequency is not always possible on account of the few commercially available transmission frequencies; where it is accomplished, however, it carries with it the disadvantage that appliances for the one room can no longer be used in the adjacent room, and are therefore incompatible. With varying numbers of pupils in the individual classes, however, such an interchange of appliances from one room to the other would be exceptionally desirable. Appliances with a frequency selector switch are more costly in regard to outlay.

For this reason, language laboratories have been arranged in which the electrical signals are transmitted from the teacher cubicle to the pupil appliance with the aid of fixed wiring. This, however, necessitates high installation expenditure, the electric wiring is expensive and makes shifting of work tables impossible and is also to some extent the cause of further susceptibility of the complicated installation to disturbance.

Common to both systems is the disadvantage that the use of them in a school makes it necessary for classes to wander from their own classroom into the room which is fitted out as the language laboratory. Such wandering results in great commotion in the school, with the result many schools are tempted not to endure this last-mentioned disadvantage, in addition to the disadvan tages already indicated, and therefore decide not to install a language laboratory.

The principal object of the present invention is to produce an apparatus for the wireless transmission of a teaching programme in instruction rooms which is economical in manufacture, but can easily be transported from one instruction room to the other, and whose transmission system is so designed that signals from the wireless transmission cannot penetrate from one room into the next and cause disturbances there.

Accordingly, the present invention consists in an apparatus for the wireless transmission of a teaching programme from a teacher appliance included in the apparatus to a plurality of pupil appliances also included in the apparatus, wherein said teacher appliance includes a housing which contains or supports a transmitter which comprises a plurality of infra-red-emitting diodes which are arranged in order to radiate in at least two different directions, at least one tape-recording playback appliance connected to said transmitter for the transmission thereby of data recorded on said tapes, a microphone socket or microphone, and controls for said microphone, said transmitter and said appliance(s), and where each pupil appliance comprises at least one earpiece constituting a headphone or headphones and accommodating an infra-red radiation recciver, a demodulator, an amplifier and a loudspeaker. Said infra-red radiation receiver may be a receiving diode sensitive to infra-red radiation, said receiving diode also acting as said demodulator.

The transmitting diodes may be arranged in three rows which are so placed relatively to one another as to transmit over as wide an arc as possible. Preferably, said rows are placed so as to form obtuse angles with one another. In a generally preferred embodiment, each of the transmitting diodes transmits over a 90" arc, measured in the vertical direction, from 30 to the horizontal to 600 to the horizontal.

The housing may have a removable cover on the inside of which further infra-red emitting diodes are mounted and which includes suspension means to facilitate hanging the cover on a wall and an electrical cable connection facilitating connection of said further diodes tasaid appliance.

The or each headphone preferably has a frame to which the receiver is attached.

An accumulator and electrical switching elements may be incorporated in the earpiece or in one of the earpieces when there are two of them. Said switching elements may be contact switches.

Said frame preferably comprises portions connection to one another by a hinge and the electrical contact switch is preferably provided adjacent said hinge.

A connection for a pupil tape recording appliance with a control device is provided on each headphone or pair of headphones.

An induction loop for an accumulatorcharging appliance may be incorporated in each headphone or pair of headphones. In such a case, a storage container with compartments for the earpieces is provided for the hcadphone pairs, each compartment for one earpicce of a pair of headphones being equipped with an induction loop which, as a primary winding, radiates the electrical energy for charging the accumulator. Said induction loop is preferably wound onto a magnetic core which extends to the outer edge of one earpiece of the headphone pair.

Alternatively, the induction loop may be wound onto a magnetic core which is fixed to the frame of the pair of headphones, a storage container with permanent magnets being provided, said permanent magnets being wound with primary induction windings, whereby the respective magnets on the pairs of headphones can be applied to the permanent magnets for charging purposes.

The apparatus may comprise a storage container for pupil tape recording appliances which is provided with induction loops, secondary induction loops being provided in the pupil tape recording appliances.

Said storage container for the pupil tape recording appliances will preferably have individual compartments which are arranged on the slant and which each carry an iron core on their respective walls, a primary winding being wound on said iron core, the respective ends of the pupil recording appliances each carrying an iron core with a secondary winding.

There may be located on the teacher appliance an ultrasonic receiver whose electro-acoustic transducer is connected to the input of the electrical control circuit for operating the teacher appliance, a portable control appliance equipped with an ultrasonic transmitter being provided which has the electro-acoustic transducer at the output of its electrical control circuit.

The housing of th teacher appliance preferably consists of a suitcase.

The present invention will now be more particularly described with reference to the accompanying diagrammatic drawings, in which: Figure 1 shows a perspective view of the teacher appliance; Figure 2 shows a view of the teacher appliance from the front; Figure 3 shows a view of the teacher appliance from above; Figure 4 shows a view of the cover of the teacher appliance from above; Figure 5 shows a view of a pupil appliance; Figure 6 shows a section through a stor age and charging cabinet for headphones of the pupil appliance of Figure 5; Figure 7 shows a view of the storage and charging cabinet of Figure 6; Figure 8 shows the view of another pair of headphones of a pupil appliance in the operational position; Figure 9 shows the view of this pupil appliance in the out-of-operation position; Figure 10 shows a view of the charging and storage cabinet for headphones of pupil appliances of Figure 8; Figure 11 shows a view of the teacher control appliance; Figure 12A shows a view of a storage and charging cabinet for pupil tape recording appliances with a control device; and Figure 12B shows a section through Figure 12A.

Referring to Figures 1 to 4, a teacher appliance is accommodated in a housing 1 in the top surface 2 of which there are two tape recording appliances 3 and two banks of operating keys or push switches 4 and 5.

The top surface 2 also carries three rows of infra-red transmitters 6, which rows are positioned at obtuse angles to each other. A collapsible or angularly adjustable microphone 7 and an ultrasonic receiver 8 are also mounted on said top surface 2.

The housing 1 can be closed by a cover 9 (Figure 4) which has a slot 10 therein adapted to coact with a suspension device (not illustrated) for hanging it on a wall. On the inside of the cover are fixed further infra-red emitters 6 which are arranged in rows and which are adapted to be connected to the teacher appliance in the housing 1 by a cable connection 11 whose plug 12 can be inserted into a socket 13 in said housing.

Figure 5 represents a pupil appliance which comprises a pair of headphones 14, which are connected together by a frame 15 which carries a microphone 16 and an infra-red receiving diode 17. The frame 15 is so constructed as to position the infra-red diode 17 obliquely in front of the pupil's chin in order to prevent it from becoming covered by hair. On the inside surface of one earpiece 14 is accommodated a contact switch 18 which, in use of the appliance, becomes pressed by the ear or the head of the pupil into a closed position thereof in which it connects the electric current consumers of the pupil appliance to an accumulator which is incorporated in one earpiece of the pair of headphones. As soon as the pupil puts down the pair of headphones, a flexible contact of this contact switch 18 is raised from the other contact and the circuit in which the accumulator has been connected is broken. These so-called electric current consumers are the infra-red receiving diode 17, a demodulator, an amplifier and a loudspeaker in each headphone.

Transmission from the teacher to the pupil appliances takes place completely via infrared rays.

In order to be able to charge up the appliances without the use of wiring and to hold them in readiness for operation, it is advantageous if each pupil appliance is provided with an induction loop 19 (Figure 6) which is accommodated in one earpiece 14 of the headphones. If the pupil appliance is placed in a storage and charging cabinet 20 (Figure 7) after termination of the teaching session, said cabinet having separate compartments 21 and 22 for the two earpieces of each pair of headphones, the charging of the accumulator which is incorporated in the pair of headphones will take place via an induction loop 23 as a primary winding and the induction loop 19 as a secondary winding, to which is connected a rectifier of a charging appliance to whose output the accumulator which is incorporated in the pair of headphones is connected. As inductional transmission from the induction loop 23 to the induction loop 19 frequently would not function sufficiently well at 50 Hertz standard frequency, a higher frequency is brought into use in these cases; for this reason, the cabinet 20 has a generator for producing the charging frequency, which generator is fed by the standard frequency.

Figures 8 and 9 show two views of another pair of headphones having a head frame 24 and a microphone holder 25 for the microphone 16, besides the two earpieces 14. The frame 24 incorporates hinges or joints 26. In the out-of-operation positions thereof shown in Figure 9, the two earpieces 14 can lie relatively closely together by virtue of said hinges, so that this part of headphones occupies exceptionally little space. The hinges 26 have a limited swivelling range; they can only be swivelled to such an extent that the resultant spacing of the earpieces 14 is always smaller than the diameter of any pupil's head. However, the frame 24 has so much elasticity or flexibility that the headphones set can easily be applied to any pupil's head and the earpieces 14 will be pressed tightly against the pupil's ears. A contact switch 27 is located on one of the hinges 26 and will be in the operating position thereof as soon as the pair of headphones is put on the pupil's head. On the other hand, in the out-ofoperation positions of said earpieces 14, this contact switch 27 is in the out-of-operation position thereof and the circuit in which the accumulator is connected is broken.

Between the two joints 26 there is an induction loop 28, which in this embodiment is wound onto a magnet core. A storage and charging cabinet 29 (Figure 10) has on the inside of it a ledge 30 with several magnet cores 31, each of which is wound with an induction loop. In order to charge the accumulator in one of the earpieces 14 in each of the pairs of headphones. the magnet core of the induction loop 28 is mounted on a magnet core 31 or suspended on the latter from below by means of magnetic forces and, as a result, there is produced a transformer with an iron core whose primary winding is situated on the magnet 31, whilst the secondary winding 28 is situated on the headphone frame. The core of the winding can be very narrow if the winding is correspondingly narrowly wound. With this device, it is possible to charge by means of 50 Hertz standard frequency, without any problems.

Figure 11 shows a view of a teacher control appliance which incorporates an ultrasonic transmitter 32 and a keyboard 5 similar to that which is available for the teacher on the appliance of Figure 1.

Another microphone 33 is also provided on this appliance. The teacher can control the teacher appliance of Figure 1 with the appliance illustrated in Figure 11 by means of the keyboard 5, whilst he walks between the rows of seats of his pupils.

There exists the possibility of connecting to each pupil appliance, by means of a cable connection, a tape recording appliance and control appliance, preferably a cassette recorder 34. Here, the same inductional charging facility is provided for each appliance; if it is placed in a storage and charging cabinet 35, in which the appliances are on a slant, so that they touch the rear walls with their respective front faces, an iron core 36 with a primary induction coil 37 is brought in contact with an iron core 38 with a secondary induction coil 39. The two cores 36 and 38 act magnetically like a single core, and a transformer with the windings 37 and 39 is formed.

A transmission system which accomplishes transmission of the teaching programme from the teaching appliance to the pupil appliances with infra-red rays has the advantage that insulation measures or screening measures between two classrooms which are separated by a wall do not have to be undertaken, and also no disturbing signals can penetrate outside through windows.

For there is so much free infra-red radiation in the free atmosphere that signals from the instruction room cannot pass through the free atmosphere into another instruction room. Thereby, not only the teacher appliance but also the pupil appliances can be so compactly and lightly designed, that all the appliances are portable. This brings the quite considerable advantage that this transmission system can be installed in any classroom as the desire arises, because the appliances can be carried without difficulty into any classroom and immediately established in the latter, and because there is no risk of signal transmissions from one room to the other. Choosing infra-red radiation as the transmission medium brings. the further advantage that the teacher can be provided with a small and radily transporfable control appliance with an ultrasonic transmitter, so as to be able to carry out control operations by means of an ultrasonic receiver fixed to the teacher appliance when the teacher is standing among his pupils and far away from the teacher appliance. Such a control appliance with an ultrasonic transmitter can easily be manufactured pocketsize.

Since the teacher appliance according to the present invention is no larger than a normal portable case and can even be constructed so as to fit in a smaller portable case, the pocket control appliance of the teacher provides the possibility of remote control, that is to say, when the teacher walks between the rows of seats of his pupils and watches his pupils' work during instruction. He can then carry out control operations on the teacher appliance from the middle of the rows of pupils. As a result, the entire installation is exceptionally readily movable and can easily be carried from one classroom to the other, even by female teachers, and deposited after lessons in special store-rooms to which the pupils have no access.

The choice of infra-red radiation for the wireless transmission of a teaching programme in instruction rooms and also the choice of ultrasonic radiation for the remote control of the teacher appliance by a pocket control appliance handled by the teacher avoids all the many disadvantages which have arisen with the transmission of a teaching programme via cable connections or via wireless radio transmission lines. The high expenditure on frequency stabilization, modulation and demodulation, screening measures and high electronic expenditure are unnecessary. Similarly, disturbance transmissions to adjacent rooms do not occur. The teacher is no longer isolated by a teacher cubicle, the teacher appliance is portable, can be accommodated in a trunk and can easily be carried from classroom to classroom. Installations with several tape recording appliances, as are required if, for example, it is desired to have classwork written in several groups, are immediately possible with relatively little expense.

It is useful if the teacher appliance is accommodated in a container whose top surface in which the operating elements, a tape recording appliance, a microphone bush (socket) a microphone, and also recording instruments which may be available are accommodated, carries the transmitting diodes. By this means, it is possible to con ceive the teacher appliance in the form of a trunk which can easily be carried from one classroom to any other classroom.

It is advantageous if the transmitting diodes are located in three rows because the teacher appliance will generally be set up on the teacher's table, as the teacher can operate the operating elements and also the tape recording appliance most advantageously at this point, and the transmitting diodes will radiate towards the pupils.

As already stated, for special circumstances, it may be advantageous for the housing to have a cover on whose inside further transmitting diodes, and on whose outside a device facilitating wall suspension, are provided. Frequently, particularly in universities, there are angularly constructed instruction rooms, e.g. lecture-rooms, in which stand pedestals in which walls engage from the sides, where it may be advantageous to provide further transmitting diodes on the top surface of the teacher appliance in addition to the transmitting diodes. These are then located on the inside of the housing cover which is suspended on the wall of the lecture-room at any point from which its diodes will be able to radiate infra-red radiator to points of the lecture-room which would otherwise be poorly served.

A connection for a tape recording appliance and a control device, e.g. in the form of a connecting socket, are advantageously provided on the headphones. By this means it is made possible for the pupil to record words spoken by him and to listen in again to the recorded words. Here there arise many possibilities of superimposition of the words spoken by the pupil with the words emitted by the teacher appliance or spoken by the teacher.

The advantages of any wireless transmission are the use of the appliance independently or regardless of its location and its troublefree use. However, the utilization the possibilities of a wireless transmission is limited by the energy sources which are available for an appliance. It is clear that only very small accumulators or batteries can be accommodated in the pair of headphones of a pupil appliance because the size of each earpiece is limited. Small batteries or accumulators necessitate in the case of batteries frequent replacement, and in the case of accumulators frequent charging. In the case of known appliances, the accumulators are made dismantlable for this purpose and are charged at a special charging station. As can be understood from the above description of Figures 6 to 10, our proposals avoid these disadvantages and provide a possibility of frequently repeated wireless recharging of the accumulators which are accommodated in the headphone of the pupil appliance. There is in fact also a possibility of charging via a connecting socket on the tape recording appliance. The storage or charging cabinet advantageously remains standing in one place with the result that the connecting cable to the mains supply can remain connected up, independently of whether the headphones are taken out to be used or are placed in the container for storage and charging.

Although the preceding description mentions pairs of earphones and although, in the majority of cases, it will be desirable to use pairs of headphones, it is to be understood that the present invention contemplates the use of the type of earphone which is carried by or otherwise mounted for use with one ear; this type of single earphone is wellknown for example in the field of playback machines used in offices by so-called audiotypists.

WHAT WE CLAIM IS: 1. Apparatus for the wireless transmission of a teaching programme from a teacher appliance included in the apparatus to a plurality of pupil appliances also included in the apparatus, wherein said teacher appliance includes a housing which contains or supports a transmitter which comprises a plurality of infra-red-emitting diodes which are arranged in order to radiate in at least two different directions, at least one tape-recording playback appliance connected to said transmitter for the transmission thereby of the data recorded on said tapes, a microphone socket or microphone, and controls for said microphone said transmitter and said appliance(s), and where each pupil appliance comprises at least one earpiece constituting a headphone or headphones and accommodating an infra-red radiation receiver, a demodulator, an amplifier and a loudspeaker.

2. Apparatus as claimed in Claim 1, wherein said infra-red radiation receiver is a receving diode sensitive to infra-red radiation, said receiving diode also acting as said demodulator.

3. Apparatus as claimed in Claim 1 or Claim 2, wherein the transmitting diodes are arranged in three rows which are so placed relatively to one another as to transmit over as wide an arc as possible.

4. Apparatus as claimed in Claim 3, wherein said rows are placed so as to form obtuse angles with one another.

5. Apparatus as claimed in Claim 4, wherein each of the transmitting diodes transmits over a 90" arc, measured in the vertical direction, from 30 to the horizontal to 600 to the horizontal.

6. Apparatus as claimed in any one of the preceding Claims, wherein the housing has a removable cover on the inside of which further infra-red emitting diodes are mounted and which includes suspension means to facilitate hanging the cover on a

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. trunk which can easily be carried from one classroom to any other classroom. It is advantageous if the transmitting diodes are located in three rows because the teacher appliance will generally be set up on the teacher's table, as the teacher can operate the operating elements and also the tape recording appliance most advantageously at this point, and the transmitting diodes will radiate towards the pupils. As already stated, for special circumstances, it may be advantageous for the housing to have a cover on whose inside further transmitting diodes, and on whose outside a device facilitating wall suspension, are provided. Frequently, particularly in universities, there are angularly constructed instruction rooms, e.g. lecture-rooms, in which stand pedestals in which walls engage from the sides, where it may be advantageous to provide further transmitting diodes on the top surface of the teacher appliance in addition to the transmitting diodes. These are then located on the inside of the housing cover which is suspended on the wall of the lecture-room at any point from which its diodes will be able to radiate infra-red radiator to points of the lecture-room which would otherwise be poorly served. A connection for a tape recording appliance and a control device, e.g. in the form of a connecting socket, are advantageously provided on the headphones. By this means it is made possible for the pupil to record words spoken by him and to listen in again to the recorded words. Here there arise many possibilities of superimposition of the words spoken by the pupil with the words emitted by the teacher appliance or spoken by the teacher. The advantages of any wireless transmission are the use of the appliance independently or regardless of its location and its troublefree use. However, the utilization the possibilities of a wireless transmission is limited by the energy sources which are available for an appliance. It is clear that only very small accumulators or batteries can be accommodated in the pair of headphones of a pupil appliance because the size of each earpiece is limited. Small batteries or accumulators necessitate in the case of batteries frequent replacement, and in the case of accumulators frequent charging. In the case of known appliances, the accumulators are made dismantlable for this purpose and are charged at a special charging station. As can be understood from the above description of Figures 6 to 10, our proposals avoid these disadvantages and provide a possibility of frequently repeated wireless recharging of the accumulators which are accommodated in the headphone of the pupil appliance. There is in fact also a possibility of charging via a connecting socket on the tape recording appliance. The storage or charging cabinet advantageously remains standing in one place with the result that the connecting cable to the mains supply can remain connected up, independently of whether the headphones are taken out to be used or are placed in the container for storage and charging. Although the preceding description mentions pairs of earphones and although, in the majority of cases, it will be desirable to use pairs of headphones, it is to be understood that the present invention contemplates the use of the type of earphone which is carried by or otherwise mounted for use with one ear; this type of single earphone is wellknown for example in the field of playback machines used in offices by so-called audiotypists. WHAT WE CLAIM IS:

1. Apparatus for the wireless transmission of a teaching programme from a teacher appliance included in the apparatus to a plurality of pupil appliances also included in the apparatus, wherein said teacher appliance includes a housing which contains or supports a transmitter which comprises a plurality of infra-red-emitting diodes which are arranged in order to radiate in at least two different directions, at least one tape-recording playback appliance connected to said transmitter for the transmission thereby of the data recorded on said tapes, a microphone socket or microphone, and controls for said microphone said transmitter and said appliance(s), and where each pupil appliance comprises at least one earpiece constituting a headphone or headphones and accommodating an infra-red radiation receiver, a demodulator, an amplifier and a loudspeaker.

wall and an electrical cable connection facilitating connection of said further diodes to said appliance.

7. Apparatus as claimed in any one of the preceding Claims, wherein the or each headphone has a frame to which the receiver is attached.

8. Apparatus as claimed in any one of the preceding Claims, wherein an accumulator and electrical switching elements are incorporated in the earpiece or in one of the earpieces when there are two of them.

9. Apparatus as claimed in Claim 8, wherein said switching elements are contact switches.

10. Apparatus as claimed in Claim 9 when Claim 8 has been appended to Claim 7, wherein said frame comprises portions connected to one another by a hinge and wherein the electrical contact switch is provided adjacent said hinge.

11. Apparatus as claimed in any one of the preceding Claims, wherein a connection for a pupil tape recording appliance with a control device is provided on each headphone or pair of headphones.

12. Apparatus as claimed in Claim 8, wherein an induction loop for an accumulator-charging appliance is incorporated in each headphone or pair of headphones.

13. Apparatus as claimed in Claim 12, wherein a storage container with compart mcnts for the earpieces is provided for the headphone pairs, each compartment for one earpiece of a pair of headphones being equipped with an induction loop which, as a primary winding, radiates the electrical energy for charging the accumulator.

14. Apparatus as clamed in Claim 12 or Claim 13, wherein the induction loop is wound onto a magnetic core which extends to the outer edge of one earpiece of the headphone pair.

15. Apparatus as claimed in Claim 12 when Claim 8 is appended to Claim 7, wherein the induction loop is wound onto a magnetic core which is fixed to the frame of the pair of headphones, a storage container with permanent magnets being provided, said permanent magnets being wound with primary induction windings, whereby the respective magnets on the pairs of headphones can be applied to the permanent magnets for charging purposes.

16. Apparatus as claimed in any one of the preceding Claims, wherein a storage container for pupil tape recording appliances is provided with induction loops and secondary induction loops are provided in the pupil tape recording appliances.

17. Apparatus as claimed in Claim 16, wherein the storage container for the pupil tape recording appliances has individual compartments which are arranged on the slant and which each carry an iron core on their respective walls, a primary winding being wound on said iron core, the respective ends of the pupil recording appliances each carrying an iron core with a secondary winding.

18. Apparatus as claimed in any one of the preceding Claims, wherein there is located on the teacher appliance an ultrasonic receiver whose electro-acoustic transducer is connected to the input of the electrical control circuit for operating the teacher appliance, a portable control appliance equipped with an ultrasonic transmitter being provided which has the electro-acuostic transducer at the output of its electrical control circuit.

19. Apparatus as claimed in any one of the preceding Claims, wherein the housing of the teacher appliance consists of a suitcase.

20. Apparatus for the wireless transmission of a teaching programme from a teacher appliance to a plurality of pupil appliances, constructed arranged and oper able substantially as hereinbefore described with reference to and as illustrated in the accompanying diagrammatic drawings.