METHOD OF ESTABLISHING A SIGNAL PATH BETWEEN AT LEAST TWO APPARATUSES AND AN ARRANGEMENT OF AT LEAST TWO APPARATUSES FOR REALISING THE METHOD

Abstract: In a system comprising a collection of signal processing apparatuses (1, 2, 3, 4) and a switching device (5), each apparatus is connected, by means of a universal con­ nector (6, 7, 8, 9) which is identical for each apparatus, to an arbitrary connection of the said switching device. The signal path between two or more connected apparatuses is established in that a first apparatus supplies a report command for the switching device in at least one further apparatus, after which the switching device finds out to which connector a further apparatus is connected in that said further apparatus in reaction to the report command has supplies an identification signal as a result of which the switching signal recognises the connector to which said further apparatus is connected. Once it has been found out to which connec­ tor the first and the further apparatuses have been connected, the switching signal establishes a signal path herebetween.

Description: The invention relates to a method of establishing a signal path between at least two apparatuses of which each apparatus is connected to a switching device by means of a respective universal connector from a plurality of connectors, the respective universal connector being identical for each apparatus, the apparatuses and the switching device being connected to a bus for transferring commands, said method comprising the step of coupling a first connector of a first apparatus of said collection via the switching device to a second connector of a second apparatus of said collection. The invention also relates to an arrangement comprising a switching device having a plurality of mutually identical connection means, each connection means comprising a respective standard connector having a plurality of pins, each connector being connected to a respective signal processing apparatus. The invention moreover relates to a switching device for such an arrangement. The invention also relates to an apparatus for use in such an arrangement. Such a method and arrangement are know from the European patent application No. EP-A-O.015.797. The various apparatuses are, for example, a television set or a video recorder. In the published arrangement, each connector is assigned an address which unambiguously identifies the connector; by putting a first address of the first connector on the bus, followed by a second address of the second connector, the connection is selected, and effected by means of controlled switches, coupled to the connectors. By reserving a fixed connector connection for each apparatus connected to the switching device, it is assured that each address also addresses a fixed apparatus. Thus, a user can connect apparatuses simply by providing the addresses associated with the connectors that need to be connected, possibly via some symbolic key, from which the address can be derived. A fixed reservation of certain connections for certain apparatuses, however, considerably restricts the flexibility in the construction of such apparatuses, and moreover is not user-friendly. When, however, said fixed reservation for certain connections is omitted and the above-described method is used, the problem occurs that the switching system does not know to which connector an apparatus is connected. Since the locations of the apparatuses are unknown the known switching device can no longer produce the signal path. It is the object to the invention to provide a method and an arrangement in which said method can be carried out, in which without using a fixed reservation of certain connections a signal path is established between at least two apparatuses which are each connected to the switching device by means of their respective universal connector. For that purpose a method according to the invention is characterized in that each connector of the plurality comprises an identity signalling pin, the first connector and the second connector being selected by the steps of generating a report command specifying the first apparatus and the second apparatus, supplying said report command on the bus, generating an identification signal from the first apparatus and transferring said identification signal to the switching device via the identity signalling pin of the first connector, recognizing the first connector to which the first apparatus is connected, by sensing the identification signal on the identity signalling pin of the first connector in the switching device, generating an identification signal from at least the second apparatus, which was specified in the report command, and transferring said identification signal to the switching device via the identity signalling pin of the second connector, recognizing the second connector to which the second apparatus is connected, by sensing the identification signal on the identity signalling pin of the second connector in the switching device. Since all the apparatuses are connected to the switching device by means of their respective universal connector the user need no longer find out to which connection a given appparatus should be connected. The switching device ensures, in cooperation with the apparatuses, that the signal path is produced. For this purpose an identification signal is conveyed to the switching device by at least one further apparatus which is specified in the report command. Since the switching device now recognises both the connection of the connector of the first and that of the second apparatus on the basis of a identification signal, the switching device is capable of establishing a signal path between these "recognized" connections. A preferred embodiment of a method according to the invention is characterized in that generating said report command involves generating a connection request signal, said connection request signal being supplied to the switching device; said recognition of the relevant connector comprises the successive steps of: reception of the connection request signal; generating an identification request signal; supplying said identification request signal via the bus to the first apparatus; generation by the first apparatus upon reception of said identification request signal, of the identification signal and supplying said identification signal to the switching device via the said predetermined pin of the first connector of said first apparatus; sequentially sensing each time the predetermined pin of the connectors by the switching device and recognition of the relevant connector having the identification signal on said predetermined pin. Detection of the connection to which the first apparatus is connected can as a result of this be realised in the same manner as detection of the further apparatus, which in turn enables a simplification of the detection means of the switching device. It is favourable for the report request signal to be presented sequentially to a further apparatus. Recognition of the connection to which the further apparatus is connected is, as a result of this, simple to realise. It is favourable for the identification signal to be formed by the provision of a modulation on the signal transfer via said pin. As a result of this an extra pin of the connector is not necessary for supplying the identification signal. A preferred embodiment of an arrangement according to the invention is characterized in that each connector has at least one standard identity signalling pin, said arrangement having a report command generator feeding the bus for providing a report command containing a first specification signal specifying at least one signal processing apparatus, and wherein any said particular apparatus comprises a report command detector fed by the bus for detecting the report command, and for when its specification is contained in the report command generating an identification signal on its identification signalling pin, wherein the switching device has identification signal detection means connected to the bus and to any identification signalling pin for detecting an identified connector to which said at least one particular signal processing apparatus is connected, said switching ddevice comprising interconnection means for thereupon establishing a signal path with the connector so detected. As a result of this, identification of the further apparatus is simple to realise. An embodiment of the arrangement according to the invention is characterized, in that it comprises connection request signal generating means including said report command generator, wherein said connection request signal contains first and second identification signals for separately identifying first and second particular signal processing apparatuses, said identity signal detection means thereupon separately detecting first and second connectors to which said first and second particular signal processing apparatuses are connected, said interconnection means thereupon establishing a signal path between the connectors so detected. It is favourable for the universal connector to be a 21-pole scart euroconnector. Universal 21-pole scart euroconnectors are generally known in audio and/or video devices. These connectors are known per se and are described, for example in "Funkschau" 18/1982, pp . 50/51. In these euroconnectors the bus is connected to the pins 10 and 12 and a switching voltage is transported over pin 8. Therefore said pin 8 is suitable for supply the identification signal hereon in the form of a modulation of the switching voltage. The invention will now be described in greater detail with reference to an embodiment shown in the accompanying drawing which represents a video arrangement in which the signal processing apparatuses are each connected to a switching device by means of a respective universal 21-pole scart euroconnector. In this example, four apparatuses, for example a TV set 1, two video recorders 2 and 3, and a video disc player 4, are connected to a switching device 5 by means of universal 21-pole scart euroconnectors 6-9. As regards their connections to the switching device these apparatuses may be interchanged arbitrarily since the connections and the connectors are identical. Each apparatus comprises a communication unit 10, 11, 12 and 13, respectively, (for example a microprocessor with ab Ho interface connected thereto) which is suitable for communication with the switching device and the other apparatuses. For this purpose the communication units are connected to a bus 14 and the conductors 17 and 20. The bus 14 is, for example, a one-line bus (D²B) as described in British Patent Specification No. 2074425. The switching device comprises a number of connections to which the 21 pole scart euroconnectors 6-9 can be connected. A data bus transceiver 15 is connected to the bus 14 in the switching device and in turn is connected to a microprocessor 16. The conductors 17 are connected to a multiplexer 18 which has an output connected to an input of the microprocessor. The conductors 20 are connected to switching means 19 a control input of which is connected to a further control output of the microprocessor 16. The bus 14 is connected to the pins 10 and 12 of the 21-pole scart euroconnectors. Via said bus are transmitted inter alia commands which originate from the switching device or from an apparatus and which are destined for one or more further apparatuses or for the switching device. The conductors 17 are connected to pin 8 of the 21-pole scart euroconnectors. Via said pin 8 inter alia a switching voltage is transported. The conductors 20 serve for the transport of signals, for example, video and/or audio signals, between two or more apparatuses of the arrangement. Each conductor 20 is formed by at least those signal lines which are connected to the pins 1 to 3, 6, 7, 11, 15, 19 and 20 of the 21-pole scart euroconnectors. Each of the corresponding remaining signal lines (connected to the pins 4, 5, 9, 13, 14, 16, 17, 18, 21) of the various connectors are connected together either directly or via the switching means 19. The communication units 10, 11, 12 and 13 are each provided with a report command generator which is connected to the bus 14 and via this bus supplies report commands for the switching device and the remaining apparatuses. The report commands comprise inter alia a connection request signal, i.e. a signal destined for the switching device 5 to indicate thereto that a signal path is to be established between the apparatus which has supplied such a connection request signal and one or more further apparatuses specified in the connection request signal. The communication units furthermore each comprise an identification signal generator an output of which is connected to pin 8 of the relevant connector. The identification signal for its apparatus, i.e. signals which are destined for switching device 5 and from which the recognition by the switching device of the connection to which the apparatus is connected becomes possible. The switching device receives a connection request signal supplied to the bus by means of its transceiver 15 and the latter passes it on to the microprocessor 16. The identification signals are presented to the multiplexer 18. The microprocessor successively senses the various connections of the multiplexer in order to recognize via which connection an identification signal has been presented. The microprocessor 16 comprises a detector generator which is designed for generating: identification request signals, i.e. bus messages generated after detection of a connection request signal to request whether the apparatus which has supplied the connection request signal wants to supply an identification signal in order to find out to which connector it is connected; detection confirmation signals, i.e. bus messages with which the switching device 5, having received an identification signal of an apparatus in question and having recognized the connector to which it is connected, requests for the removal of the identification signal from the conductor 17 on which it is set; report request signals, i.e. bus messages generated after detection of a connection request signal or a report command, by which, by means of a key, the connected apparatuses, or those which were specified in the connection request signal, are requested to supply an identification signal. The identification signal is preferably formed by a modulation on the switching voltage present on the line connected to pin 8 of a connector. As a result of this it is not necessary to use a separate pin of the 21-pole scart euroconnector for the identification signal and moreover the detection of said identification signal is simple to realise by the switching device. Since said identification signal is the same for all the connected apparatuses (in fact only the connection is to be recognised) it will suffice to scan sequentially the inputs of the multiplexer. Said scanning is done under the control of the microprocessor 16 which scans the various inputs of the multiplexer and finds out whether a modulation signal is present on one (or more) of said inputs. Upon detection of a modulation signal at a scanned input the microprocessor establishes on which input said modulation signal is present. As a result of this the microprocessor is capable of recognising to which connector an apparatus is connected. When the microprocessor 16 has established, by means of scanning the inputs of the mutiplexer 18, to which connection the apparatus with which a connection is desired is connected and has also established to which connection the apparatus which desires the connection is connected, the switching means 19 are activated under the control of the microprocessor in order to establish a signal path between these apparatuses. The switching means are formed, for example, by a programmable switching matrix. It will be obvious that a signal path can be established between more than two apparatuses. This may be the case as a result of a detection of an identification signal at more than one input of the multiplexer. The multiplexer 18 is constructed, for example, from a collection of AND gates or from a collection of flip-flops which each have one input connected to a line from the conductor 17. Let it be assumed that information originating from the video recorder 2 is to be displayed on the TV set 1. From the communication unit 11 of the video recorder 2 a connection request signal is supplied over the bus 14 and via the transceiver 15 to the microprocessor 16. In the microprocessor 16 the source of said signal is known by decoding the connection request signal but not the connector to which said source is connected. Hence that it is initialised from the microprocessor 16 that an identification request signal for the video recorder 2 is supplied over the bus 14. The video recorder then detects this identification request signal and supplies an identification signal via the conductor 17; this identification signal is detected by the microprocessor 16 via the multiplexer 18 and thus connector 7 to which the video recorder 2 is connected has been recognised. From the microprocessor 16 a detection confirmation signal for the video recorder 2 is supplied over the bus 14, as a result of which the identification signal is removed from the conductor 17 in question. By decoding the connection request signal the microprocessor 16 has established that a connection to a TV set is to be established. The microprocessor 16 then generates a report request signal for a TV set and supplies it to the bus 14. In an alternative embodiment a report command which comprises a connection request signal fro the switching system is sent to all connected apparatuses via the bus. By decoding such a report command an apparatus is then capable of finding out whether it is specified in the report command or not and, if so, to then generate an identification signal. As a result of this it is not necessary to generate a connection request signal. By decoding a received report request signal an apparatus finds out whether it may be involved in producing the signal path. This examination occurs, for example, by comparison of an identification, for example, an address or an indication code, incorporated in the report request signal (or in the report command) which in this example indicates that a connection to a TV set is desired. For performing the comparison the communication unit of the TV set comprises a memory element for storing its own key. Said memory element is connected to a comparator in which the own key is compared with the presented key. When the own key corresponds to the presented key this means that the apparatus in question is involved in the signal transmission and an identification signal is generated. By supplying said identification signal via the conductor 17 in question, the switching system is now capable of recognising that the TV set is connected to connector 6. In this case also a detection confirmation signal is now supplied from the microprocessor 16 via the bus connection 14 to the TV set so that it can release the conductor 17 in question. It is now established in the microprocessor that a signal path is to be established between the TV set 1 and the video recorder 2, that the TV set is connected to the connector 6 and the video recorder is connected to the connector 7; the microprocessor 16 then provides such a control signal to the switching means 19 that therein the signal path is produced between the apparatuses connected to the connectors 6 and 7. A more complicated system is obtained when all connected apparatuses (i.e. all the apparatuses with the exception of that one from which the connection request signal originates) react to the report request signal from the switching device. Each connected appaatus then reports via pin 8 as a modulation on the signal transmitted via said pin so that identification of all the connected apparatuses is possible. All these signals with modulation identification are detected so that in the microprocessor 16 the desired apparatus can be selected herefrom. Finally it is to be noted that the switching system 5 may form both a separate unit and may be incorporated in one of the apparatuses, for example, in the TV set 1; in that case the apparatuses 2, 3 and 4 are connected to the TV set, i.e. to the switching device 5 provided therein.

Claims: A method of establishing a signal path between at least two apparatuses belonging to a collection of apparatuses of which each apparatus is connected to a switching device by means of a respective universal connector from a plurality of connectors, the respective universal connector being identical for each apparatus, the apparatuses and the switching device being connected to a bus for transferring commands, said method comprising the step of coupling a first connector of a first apparatus of said collection via the switching device to a second connector of a second apparatus of said collection, characterized, in that each connector of the plurality comprises an identity signalling pin, the first connector and the second connector being selected by the steps of generating a report command specifying the first apparatus and the second apparatus, supplying said report command on the bus, generating an identification signal from the first apparatus and transferring said identification signal to the switching device via the identity signalling pin of the first connector, recognizing the first connector to which the first apparatus is connected, by sensing the identification signal on the identity signalling pin of the first connector in the switching device, generating an identification signal from at least the second apparatus, which was specified in the report command, and transferring said identification signal to the switching device via the identity signalling pin of the second connector, recognizing the second connector to which the second apparatus is connected, by sensing the identification signal on the identity signalling pin of the second connector in the switching device. A method as claimed in Claim 1, characterized in that generating said report command involves generating a connection request signal, said connection request signal being supplied to the switching device; said recognition of the relevant connector comprises the successive steps of: reception of the connection request signal; generating an identification request signal; supplying said identification request signal via the bus to the first apparatus; generation by the first apparatus, upon reception of said identification request signal, of the identification signal and supplying said identification signal to the switching device via the said predetermined pin of the first connector of said first apparatus; sequentially sensing each time the predetermined pin of the connectors by the switching device and recognition of the relevant connector having the identification signal on said predetermined pin of the first connector. A method as claimed in Claim 2, characterized in that, after receipt of the connection request signal, a report request signal is generated by the switching device which report request signal comprises a key for the second apparatus specified in the connection request signal and is transferred via the bus to the second apparatus, and in which it is verified by the said second apparatus after receipt of the report request signal whether the further apparatus is identified by the key and in which the identification signal is generated if the second apparatus has been identified by the key. A method as claimed in Claim 3, characterized, in that the first apparatus generates the report command for a further apparatus, a further report request signal being presented to the further apparatus after the report request signal has been presented. A method as claimed in Claim 2 or 3, characterized in that, after recognition of an identification signal, a confirmation signal is generated by the switching device and is applied to the apparatus which has generated the identification signal. A method as claimed in any of the preceding Claims, characterized in that the identification signal is formed by providing a modulation on the signal transferred via the said pin. Arrangement comprising a switching device having a plurality of mutually identical connection means, each connection means comprising a respective standard connector having a plurality of pins, each connector being connected to a respective signal processing apparatus, characterized, in that each connector has at least one standard identity signalling pin, said arrangement having a report command generator feeding the bus for providing a report command containing a first specification signal specifying at least one signal processing apparatus, and wherein any said particular apparatus comprises a report command detector fed by the bus for detecting the report command, and for when its specification is contained in the report command generating an identification signal on its identity signalling pin, wherein the switching device has identification signal detection means connected to the bus and to any identity signalling pin for detecting an identified connector to which said at least one particular signal processing apparatus is connected, said switching device comprising interconnection means for thereupon establishing a signal path with the connector so detected. An arrangement as claimed in Claim 7, characterized, in that it comprises connection request signal generating means including said report command generator, wherein said connection request signal contains first and second specification signals for separately specifying first and second particular signal processing apparatuses, said identity signal detection means thereupon separately detecting first and second connectors to which said first and second particular signal processing apparatuses are connected, said interconnection means thereupon establishing a signal path between the connectors so detected. An arrangement as claimed in Claim 8, characterized, in that each processing apparatus has only a single identification signalling pin, and said first and second particular signal processing apparatuses generate their respective identification signal at different instants in time. An arrangement as claimed in Claim 7, 8 or 9, characterized, in that the identification signal is a key and any report command detector contains a comparator for comparing said key to a locally stored privy key. An arrangement as claimed in any of Claims 7-10, characterized, in that said switching device has a confirmation signal generator feeding said bus for upon detection of any identification signal generating a confirmation signal on the bus. An arrangement as claimed in any of Claims 7 through 11, characterized, in that said switching device is physically located within one predetermined apparatus of said signal processing apparatuses. An arrangement as claimed in any of Claims 7 through 11, characterized, in that said report command generator is physically located within one predetermined apparatus of said signal processing apparatuses. An arrangement as claimed in any of Claims 7 through 11, characterized, in that any identification signal has a uniform electrical signal shape. An arrangement as claimed in any of Claims 7 through 11, characterized, in that said serial command bus in each signal processing apparatus is connected to at least one particular bus pin, of its associated standard connector. An arrangement as claimed in Claim 15, characterized, in that said serial command bus in each signal processing apparatus is connected to two uniformly arranged bus pins of its associated standard connector. An arrangement as claimed in any of the Claims 7 to 16, characterized in that the universal connector is a 21-pole scart euroconnector. An arrangement as claimed in Claim 17 characterized in that the bus connected to the pins 10 and 12 and that pin 8 is the predetermined pin. An arrangement as claimed in any of the Claims 7 to 18, characterized in that the bus is a one line bus. An arrangement as claimed in any of the Claims 7 to 19, characterized in that the signal path is destined to transfer audio and/or video signals. A switching device for use in an arrangement as claimed in any of the Claims 7 to 19 characterized in that the switching device comprises detection means for detecting report commands and identification signals and comprises switching means for producing a connection between connections on which report commands and/or identification signals have been detected. An apparatus for use in an arrangement as claimed in any of the Claims 7 to 21, characterized, in that the apparatus comprises a report command detector and an identification signal generator. An apparatus according to Claim 22, characterized in that it comprises a report command generator.

Inventors: BERKHOFF, EGBERTUS JACOBUS, VAN STEENBRUGGE, BERNARD
Applicants: N.V. PHILIPS' GLOEILAMPENFABRIEKEN
Application year: 1987
Main classification: H04B1
IPC codes: H04B1