Improved building intercommunication system with digital calling

Abstract: A building intercommunication system comprising at least two buses (A-B) for connection between the outdoor stations and the indoor stations, and from which the plurality of outdoor stations (10) and the plurality of indoor stations (20) branch off respectively, and at least one coupling component (30) which is interposed between the two buses, further comprising a circuit (31-33, 32-34) for separately supplying the two buses (A-B), electronic means (35-36-µP) adapted to receive and retransmit in both directions, from and onto the buses, frames of digital signals for selecting, and for answering from, the individual indoor stations (20); and adapted to enable an audio circuit (38) which resides within the coupling component and allows the bidirectional travel of the audio signals from one bus to the other (A-B) and accordingly from the calling outdoor station (10) to the called indoor station (20) and vice versa.

Description: The present invention relates to an improved building intercommunication system of the type with digital calling, wherein the expression "building intercommunication system" describes a signaling and answering system for domestic use, comprising one or more outdoor stations for calling, and selectively establishing voice communication with, a plurality of indoor stations or user intercom sets and for the activation, on the part of said indoor stations, of an electric lock (so-called electric door opener). More particularly, the present invention relates to a building intercommunication system as specified, of the type in which the selection of the individual indoor stations and the activation of the electric lock are performed by means of digitally coded pulses and wherein the selection signal is decoded by individual call detectors, each of which is associated with a corresponding indoor station or user intercom set. Building intercommunication systems of this type are known for example from DE-195 48 744; in such systems, the outdoor station or stations and the indoor stations or user intercom sets are arranged along a common bus with two conductors, which is used both for transmitting digital signals related to selection and to the electric gatekeeper function and for transmitting the audio signal related to the conversation. These conventional building intercommunication systems, although being efficient and relatively simple, have drawbacks; the greatest drawback is the fact that the electrical connection provided by means of said bus introduces considerable attenuation in the transmission of the selection and audio signals, so that in general the architecture of the systems is rigid and scarcely expandable or not expandable at all, in terms of outdoor stations and indoor stations or user intercom sets as well as in terms of physical location of the various components of the system. European Patent application no. EP0818914 discloses a building intercommunication system in which an outdoor station and a plurality of indoor stations are connected to each other by means of a line having two wires and with the interposition of junction boxes, each box handling a corresponding group of intercom sets. European Patent application no. EP0032982 discloses a domestic system for information transmission comprising a plurality of subscriber's sets interconnected without central exchange. European Patent application no. EP0849913 discloses a data communication system comprising two buses and connection means for converting a packet format of an asynchronous transmission mode from one bus to the other and vice versa. The aim of the present invention is to eliminate this drawback and therefore to provide an improved building intercommunication system which can be expanded in any manner according to operating requirements and as said requirements change, for example by adding to a first set of outdoor and indoor stations, planned during the design of a building, additional sets of outdoor and/or indoor stations with different physical locations, required by subsequent extensions or partitionings of the building or by the subsequent construction of utilities and other structures related to said building. Within the scope of this aim, an object of the present invention is to provide an improved building intercommunication system which, in case of localized malfunctions, allows to selectively disconnect individual blocks of user intercom sets without compromising the entire functionality of the system. Another important object of the present invention is to provide a building intercommunication system of the specified type, with a highly simplified programming system and requiring the intervention of a single operator, who provides a correlation between the outdoor station and the indoor stations by means of correlation data generated by the outdoor station and stored in the individual indoor stations. According to the present invention, this aim, these important objects and others which will become apparent from the following detailed description are achieved by an improved building intercommunication system having the specific characteristics stated in the appended claims. Substantially, the invention is based on the concept of using two buses as a line for connection between the outdoor stations and the indoor stations, each bus comprising two non-polarized conductors, a plurality of outdoor stations branching off from one of said buses, a plurality of indoor stations branching off from the other one of said buses; and in interposing between said buses a coupling circuit component, to which both buses are connected, said coupling component being provided with means for separately supplying said buses, with electronic means adapted to receive and retransmit in both directions, from and onto said buses, frames of digital signals for selecting, and for answering from, the individual indoor stations; and adapted to enable an audio circuit which resides within the coupling component and allows the bidirectional travel of the audio signals from one bus to the other and accordingly from the calling outdoor station to the called indoor station and vice versa. Further characteristics and advantages of the improved building intercommunication system according to the present invention will become apparent from the following detailed description and with reference to the accompanying drawings, given by way of non-limitative example, wherein: Figure 1 is a general diagram of the system; Figure 2 is an enlarged-scale view of a detail of Figure 1, illustrating in greater detail the coupling component interposed between the two buses of the system. In the drawings, the reference numeral 10 generally designates a plurality of outdoor stations, each of which comprises, in a fully known and conventional manner, a set of name-tag call buttons 11, audio transducers 12-13 constituted respectively by a loudspeaker and by a microphone cartridge, and an electric lock 14 (so-called electric door opener). The reference numerals 20-20' designate one or more pluralities of indoor stations or user intercom sets, which are also constituted by conventional intercom sets provided with a buzzer and with a door opening button for activating the electric lock 14. According to the present invention, the connection between the outdoor stations 10 and the indoor stations 20, both for selection and for the subsequent transceiving of audio signals, is performed by means of two buses, respectively A and B, each of which comprises two non-polarized conductors C1-C2. The plurality of outdoor stations 10 is branched off the bus A and the plurality of indoor stations or user intercom sets 20 is branched off the bus B; the bus B is preferably divided into a series of backbones, for example four backbones d1...d4, which facilitate the selective disconnection of the system in case of malfunction. A circuit component 30 is interposed between the bus A and the bus B and acts as a coupling device between the outdoor stations 10 and the indoor stations 20. The coupling component 30 is provided with electronic and audio circuits which allow it to perform the following substantial functions: supplying the two buses A and B connected thereto, receiving and retransmitting in both directions from and onto said buses A-B frames of digital signals for selecting, and answering from, the individual indoor stations 20, allowing the transit of bidirectional audio signals from the bus A to the bus B and vice versa, accordingly allowing conversation between a generic calling outdoor station and a generic called indoor station. In order to supply power to the buses, the coupling component 30 comprises a first power supply circuit 31 which is associated with the bus A and a second power supply circuit 32 which is associated with the bus B. The power supply circuits are both connected to the corresponding bus with respective audio decoupling circuits 33-34, shown schematically in the figure as an electronic switch, or a plurality of switches in the case of a plurality of bus backbones, which are controlled for opening and closing by a microprocessor µP of the coupling component 30. Actually and typically, the circuits 33-34 include an inductor whose impedance is varied, by means of an active element which acts as a switch, by the microprocessor µP as a function of the operating state of the system in order to assume a value which is close to zero during the inactive steps or during digital data transmission steps, and a high nominal value during audio transmission in order to decouple the buses A and B from the respective power supply circuits 31-32. For the selection or addressing of the indoor stations 20, each outdoor station 10 comprises a call frame generator (which is known and not shown) which is associated with its name-tag buttons 11, and the coupling component 30 comprises a first data transceiver 35 and a second data transceiver 36 which are associated with the microprocessor µP. The transceiver 35 comprises on one side an output Rx for receiving data from the bus A and an input Tx for transmitting data over said bus; the output and the input are connected to corresponding pins of the microprocessor µP, and the transceiver is electrically connected to the bus A with a polarity reversal-preventing bridge 37. Likewise, the transceiver 36 comprises an output Rx for receiving data from the bus B and an input Tx for transmitting data on the same bus B. Data transmission over both buses occurs in PWM mode, modulating to zero (ground) the voltage of the respective bus. For this purpose, both transceivers 35 and 36 comprise a respective modulation transistor Tr which branches off the respective bus and receives, on its base, a control voltage which is produced by the microprocessor µP and is adapted to saturate said transistor and accordingly short-circuit to the ground the corresponding bus. In order to compensate for the lack of voltage on the bus during the transmission steps, each device connected to the bus has a flywheel capacitor (not shown) which provides it with the necessary operating voltage. For audio transmission, the coupling component 30 further comprises an audio circuit 38 for bidirectional audio connection of the two buses. The audio circuit is controlled by an activation command K which is output by the microprocessor µP, and comprises, in a per se known circuit configuration, two operational amplifiers A1-A2 which are mutually and directionally connected to respective output circuits 39-40 of the so-called fork type, which allow the bidirectional transit of said signals; the amplifiers A1-A2 being adapted to regenerate by amplification the audio signals that arrive from both buses. As clearly shown in Figure 1, the described system provides for the installation of two or more coupling components 30 in order to connect to the bus A two or more buses B-B' which comprise additional pluralities of indoor stations 20-20' etcetera. In this case, the additional coupling components such as 30' etcetera are operatively connected to the coupling component 30 in a master-slave relation and the coupling component chosen as master supplies all the devices connected to the bus A and in particular the outdoor stations 10. The operation of the above-described building intercommunication system is as follows: The outdoor station 10 that needs to call a generic indoor station 20, following the activation of the corresponding name-tag button 11, transmits over the bus A a corresponding address or call frame. The coupling component 30, or as an alternative the coupling components 30-30' etcetera, receive the address frame from the bus A and send the frame to the microprocessor µP by means of the output Rx of the respective transceiver circuit 35. The microprocessor correspondingly modulates the transistor Tr of the output Tx of its own transceiver circuit 36 so as to retransmit the frame over the bus or buses B; in the illustrated example, over all four backbones of said bus or buses. When the address frame is received, the microprocessor µP also activates the closure of the audio decoupler or decouplers 34 and keeps the bidirectional audio connection circuits 38 off at the same time. All the indoor stations 20 therefore receive the address or call frame, but only the intercom set that is preset to recognize said frame activates its buzzer, simultaneously sending over the bus B a "presence" frame. The coupling device 30 that receives said presence frame by means of its transceiver 36 retransmits it over the bus A by means of the microprocessor µP and the output Tx of its own transceiver 35. When the outdoor station 10 receives the presence frame (which must arrive within a certain period τ), it enables its audio circuits and transmits an audio enable frame over the bus A. The frame reaches the related microprocessor µP via the transceiver 35 and the microprocessor enables the audio circuit 38 of its coupling component 30 and retransmits the frame over the bus B connected thereto so that the indoor station 20 that receives the frame in turn enables its own audio circuit, at the same time transmitting a "busy" signal to the coupling device 30. From this time onward the conversation between the calling outdoor station and the called indoor station can begin. From the above description it is evident that the building intercommunication system according to the invention is subjected to preliminary programming, which is meant to provide a correlation between the outdoor stations 10 and the indoor stations 20, associating the latter with the corresponding name-tag buttons 11 of the outdoor stations. For this purpose and according to the invention, each indoor station 20 is provided with a local microprocessor with which an EEPROM memory (not shown) is associated. The memory contains the identification code of the intercom set being considered, which is generated by the outdoor station during programming. The programming can therefore be performed by a single operator and consists in sequentially reserving name-tag buttons to be associated with the various indoor stations and in then going, in the same sequential order, to the indoor stations in order to terminate the correlation, which is indicated by a confirmation tone. Without altering the concept of the invention, the details of execution and the embodiments may of course be altered extensively with respect to what has been described and illustrated by way of non-limitative example without thereby abandoning the scope of the invention. The disclosures in Italian Patent Application No. TO98A000901 from which this application claims priority are incorporated herein by reference. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims: A building intercommunication system with digital calling, having a plurality of outdoor stations (10) and a plurality of indoor stations (20), characterized in that it comprises means for connection between the outdoor stations and the indoor stations, said means being constituted by at least two buses (A-B), each bus comprising two non-polarized conductors (C1-C2), from which buses (A-B) the plurality of outdoor stations (10) and the plurality of indoor stations (20) branch off respectively, and by at least one coupling component (30) which is interposed between said at least two buses and comprises: circuit means (31-33, 32-34) for separately supplying the two buses (A-B), electronic means (35-36-µP) adapted to receive and retransmit in both directions, from and onto said buses, frames of digital signals for selecting, and for answering from, the individual indoor stations (20); and adapted to enable an audio circuit (38) which resides within the coupling component and allows the bidirectional travel of the audio signals from one bus to the other (A-B) and accordingly from the calling outdoor station (10) to the called indoor station (20) and vice versa. The building intercommunication system according to claim 1, characterized in that said coupling component (30) comprises individual power supply circuits (31-32) for said at least two buses (A-B) and in that said circuits (31-32) are connected to the respective buses with corresponding audio decoupling devices (33-34) interposed, said decoupling devices being subjected to activation and deactivation commands. The building intercommunication system according to claim 1, characterized in that said electronic means that reside in the coupling component (30) comprise, for the bidirectional transit of the digital signals, a microprocessor (µP) which cooperates with two transceivers (35-36), each of which is operatively connected to a respective bus (A-B) of said at least two buses, and in that each transceiver receives from the respective bus (A or B) a frame of signals, which it retransmits to the other bus (B or A), and retransmits over the respective bus (A-B) the frame of signals that it receives from said other bus (B-A). The building intercommunication system according to claim 3, characterized in that said transceivers (35-36) comprise, for retransmitting the frame of signals arriving from said other bus (A-B), a transistor (TR) which, under the control of a microprocessor (µP), modulates the voltage of the bus so as to correspond to said signal frame. The building intercommunication system according to claim 4, characterized in that the frame of signals is transmitted over both buses in PWM mode, modulating to zero (ground) the voltage of the corresponding bus. The building intercommunication system according to claim 1, characterized in that said electronic means that reside in the coupling component (30) comprise, for the bidirectional transit of audio signals from one bus to the other (A-B), an audio circuit (38) controlled by an activation command (K) which is output by said microprocessor (µP) and comprises two operational amplifiers (A1-A2) which are mutually and directionally connected to respective output circuits (39-40) of the fork type which allow bidirectional transit of said audio signals. The building intercommunication system according to claim 1, characterized in that it comprises two or more coupling components (30-30') for connecting one of the buses (A), which comprises said plurality of outdoor stations (10), two or more buses (B-B') which correspondingly comprise two or more pluralities of indoor stations (20-20'); in that said coupling components (30-30') are mutually connected in a master-slave arrangement; and in that the master coupling component (30) supplies said one of the buses (A) which comprises the plurality of outdoor stations (10). The building intercommunication system according to claim 1, characterized in that said bus (B) from which the plurality of indoor stations (20) branch off is divided into two or more backbones. The building intercommunication system according to claim 1, characterized in that each indoor station (20) or intercom set comprises a local microprocessor with which an EEPROM memory is associated, and in that said memory contains the identification code of the set (20) being considered, generated by the outdoor station (10) during programming. The building intercommunication system according to claim 1, comprising one or more outdoor stations (10) for calling and selective voice conversation with a plurality of indoor stations (20) or user intercom sets and for the activation, on the part of said indoor stations, of an electric lock.

Inventors: MONDARDINI MASSIMO, MONDARDINI, MASSIMO
Applicants: URMET DOMUS S P A, URMET DOMUS S.P.A.
Application year: 1999
Main classification: H04M11
IPC codes: H04L12