CA1198843A - System for transmitting messages to a telephone set through the subscriber's line in a telephone system - Google Patents

Abstract

"System for transmitting messages to a telephone set through the subscriber's line in a telephone system"

ABSTRACT OF THE DISCLOSURE

A message transmitting system incorporated in a tele-phone system and comprising a device for generating service signals relating to the making of a telephone connection between one telephone set and another telephone set, the system comprising a mixer with two inputs which are connected to the service signal generating device and to a message generating device, respectively, the output of the mixer being connected to the telephone line.

Description

"System for transmitting messages to a telephone set through the subscriber's line in a telephone system"

The present inver~ion relates to a system for -trans-mitting messages to a telephone set through the telephone line associated therewith in a telephone system or plant comprising a device~r ~n~a~ng servioe si~Els relating to the making o~ a telephonic connection or communication between this set and another telephone set, These service signals such ~or instance as operating signals, free line or dial tone or ringing tone signals, back-cal.ling signals, routing or busy signals are sent to any user of a telephone set who has unhooked or li~ted the handset and wishes tosend a call -to another ^telephone set or is doing ito This telephone line requesting user should take such service signals into consideration because they advise him about the state o~ the telephone network or system determining the progress of -the calling procedure and indicating whether his call has or has not succeeded~
This means tha-t the user is listening during substantially the whole period o~` establishing the communication except ~or t~e dialling or keyboard operation times.
The object o~ -the present invention is to pro~ide a system for transmit-ting during the periods o~ presence of such service signals or at least of some of such signals, messages, ~or instance solmding messages such as advertlsing texts or o~ any other character or music.
To achieve such a goal the Jnessage transmitt:ing system according to the invention comprises a rnixer with two inputs which are connected to the service signal generating device and to amessage generating device, respectively, the output of the mixer being cor~ected to 10the telephone line.
According to an advantageous characterizing fea-ture of the invention the system comprises a ser~ice signal and ~essage emission synchronizer, According to another advan-tageous characterizing feature of the invention the mixer consists of a transformer with two primary windings and one secondary winding and the free -terminals of the windings are constituting the inputs of the mixer, the common terminal of the windings being grounded or earthedO
Still another object of the present invention is to provide a system ~or transmitting messages to a telephone set completed with a display or viewing screen and, if need be, ~urther message receiving means such as a printing device. This telephone set having thus ra-ther become a subscriber terminal is there~ore adapted to be connected to a telematic network designed ~`or data transmission. This terminal ~or instance could be connected to a videophonic network or to a dat~b~7k consulting network.
For accomplishing such an object, the message trans-30 mission system according to the present invention ischaracterized in that the message generator consists o~ a signal such as data signal emitting device adapted to be reproduced in the telephone set o~ the subscriber calling for or re~uesting the making o~ the telephone connection onto a support such as a viewing and/or printing screen, this emitting device being connected to the input o~ a mixer ano-ther input of which receives the service signals and -the output o~ this mixer being adapted to be connected to the calling subscriber line1 According to an advantageous characteri~ing fea-ture o~ the prese~t invention the transmission systern co~nprises a separator for separating the service si~lals from the signals to be reproduced onto a support, wi.thin the subscriber's telephone set or s-ta-tion.
According to still another advan-tageous characterizing ~eature, the transmission sys-tem comprises a service signal presence detector and, if need be, a detector for sensing the moment o~ the response of the called subscriber's set or station, both detectors being connec-ted to a control circuit for putting the message generator on and off, respecti.vely.
According to still a furth~r advantageous character-izing ~ea-ture of -the invention, the subscriberls set or station is fitted with a storage device or memory ~or storing the information received from -the message .
generator during the time period o~ making the connection with the called subscriber's set or s-tation and for reproducing such information at any desired suitable time onto the support such as the viewing screenO
The invention will be better understood and further objects, characteri~ing features5 details and advantages thereof will appear more clearly as the following explanatory description proceeds with re~erence to the accompanying diagramma-tic drawings given by way of non-limiting examples only, illustrating two embodiments of the invention and wherein -- Figure 1 shnws as a block diagram the principle of the message transmitting system according to the present nvention;
- Figure 2 shows the arrangement of the synchronizer of the block diagram according -to Figure 1; and - Figure 3 illustrates another embodiment o~ the . 4 lnvention for vlsually displaying messages"
As shown in Figure 1, a telephone plant or arrangernent to which the presen-t invention is applicable coMprises a device for ~enera-t;.ng special e~ectr;,c currents GS adapt~d the emi.ssion of a number of se~ice si~la]s such as operati.n~ signals, back-ca]l sig~a],s, routi.ng si.gna]s, busy signals, calling signals and so on. These s;.gnals are sent to c-very subscriber's ,set or station the handset of which has been withdra~m with a view of providing from ~0 this set or station a telephone connection with another subscriber's set or station. Accordi,ng -to Fi~re 1, the ser~ice signals are conveyed to the communication calling -telephone set successively through telephone line sections A and B and a telephone network section SR. Each one of the different sections SR (only two of which are shown by way of example) is connected to the line section B by a translor~ler TRS.
As appearing from Figure 1, the direct com1ection be-tween the telephone line sections A and B may be broken off by means of a change-over switch IN1 for connecting the message transmitting system according t.o the present invention be-tween both line sections~
'l'his system cornprises a ~ixer TRM with two inputs E1,E2 and an outpu-t S. In the exa~ple shown, the mixer consis~ts of a transformer with two pri.mary windings which are molmted in series and the cornmon point of which is grolmded or earthed. The free terrninal of each primary winding forms one o~ the two inputs E1,E2 of the mixer.
The input E1 is connected to the output of a differential ampli~ier device AM the control or drive input of which is connec~ted to the input line sec~ion A through the agency of the switch IN1. The input E2 of the transformer-mixer TRM is likely to be connected to a message ~or instance a sound;ng message generating device through the medium of an attenuator AT, a changeover switch IN2, a synchron-swtichizing circuit CS, a changeover/IN3 and a suitable trans-swltcn former TRG. A changeover/ IN4 makes it possible to withdraw the synchronizer CS from the circuit interconnec-ting the rnixer TRM and the message generator GM~ The :input and I;he output, for i,he messages -to be -transMitted, of -l;he synchroni~ing circuit CS are designa-ted by the re~erence characters E1 and S~ The synchronizing circuit CS
comprises a second input E2 at which it receives the service signals fro~ the line section A~ '~he arrangernent 10 of the synchronizing circuit CS wi1l be described in detail hereinafter.
As to the arrangement of the arnpli~ier AM, it is seen tha-t its control input is connected to the contact slide of a potentiometer P1 connected with one terminal to the line section A~ The other terminal is grounded or earthed.
The OlltpUt of the amplif;er AM1 is connected through a capacitor C1 to the input E1 of the transfol-mer-mixer 'i'RM.
A series-connected circuit consisting of a capacitor C2 and a resistor R1 is interposed between this inpu-t and 20 -the ground or ear-th. The output of the amplifier AM is, moreover, connected through -two series-connected resistors R2,R3 to the ground or earth. The second input E2 of the amplifier is co~nected through a capacitor C3 to the common point of both resistors R2,R3. I-t is further seen tha-t a capacitor C4 is connected across the input E1 of the amplifier AM and the ground.
It should be pointed out that the message-generating device GM could cornprise one or several (for instance two, as in Figure 1) cassette or record pick-up or reading 30 devices and emergency generators or ~vices ~ anyo~erk~ It is advantageous that a ~enerator which operates in princip7e continuous]y without a stop be a record generator, whereas a cassette generator is more s~itable for the transmission of specific messages because it offers t~le advantage o~ a quick cassette changing. In addition to ~he message-generator GM, the system according -to -the 5~ .

invention could colnprise an outer rnodula-tion source SME
for the transmission of particular and occasional messages~
This source could be connected to the mixer ~`RM instead of the genera-ting device GM either direct]y -through the switch IN2 or through the rnediuln o~ the synchron-izing circuit by pu1ting the swi-tch IN3 in its position not sho~m.
The arrangemen-t of the synchroni~ing circuit CS wi]l be described hereinafter with reference to Fi~lre 2.
~0 The synchronizing circuit cornprises two parts, narnely a first part I for the on/off ~ontrol of the message-generating device G~ and a second par-t II adapted to rnake or to cut off the connection between the generating device GM and t;he mixer TRM. The action of the part I upon -the generating device GM is substantially shown on Figure 1 ~y the arro~ed line F.
The par-t I is connected to the service signal receiving input E20 It coJnprises a flip-flop BA1 consisting of two NOR gates P1,P2 having each one two inputs. As known per se 20 the output of one gate is connected -to the input of the other gate. The free input of each gate forms one input of the flip-flop~ The free input of the gate P1 is connected to *he input E2 of the s~chronizing circuit CS which is adap-ted -to recei~e the service signals, through the agency of a circuit which essentially comprises an input trans-former TRC9 a low--pass filter PB, a Schmitt trigger circuit ~S1, an inverter IV1 and a di~feren ti-a1 Ci rCUit CD1 a rrhe la-tter cornprises a capaci-tor CG connected between the inverter IV1 and the input Qf 30 the gate P1 and a parallel co-mection of a resistor R5 and of a diode D1, ~lich connects -this input to the groundO
It is the anode of the diode which is grounded. As a Schmitt trigger circuit is used a series connection of two inverters IV2,~V3 consisting each one of a NOT-~D or NAND
gate the inputs of which are connected together. A
resistor R6 is mounted in parallel relation to the inverters~

`~``

The lo~-pass ~ilter PB co~prises a capacitor mounted in parallel relation to the secondary winding of the trans-~oroler TRC and a series connection of a variable resistor R7 and a resistor R8 connec-ted across the secondary winding of the transformer and -the Schmitt tri~ger circui-t BS1 The common point of both resis-tors R8 ~nd R 7 is connected to the ca-thode of a dlode D2 the anode of ~hich is grounded. This cormnon point is, moreover, connected -to the stationary con-tact piece of a switch but-lon B1. The 10 movable contact of the ]atter is connected to a positive voltage potential through a resistor R9 At rest, the switch is in its open position.
The output of the gate P1,which forms an ou-tput oE the flip-flop BA1,is connected through the agency of a resistor R10 to the base of a switchi~1g transistor T1. In the emit~ter circuit of this transistor are series-connected a resistor R11 and a light-emitting d;ode DE1~ This diode is emitting a ]i~ht for instance of red colour~ The emitter of the -transistor T1 forms an outpu-t of the 20 control circuit ~or ~the message-generating device GM.
The ~ree input of the gate P2,~Jhich forms the second input o~ the flip-flop BA1, is connected to a voltage divider consisting of a resistor R12 connected to a positive potential and a variable resistor R13 ~hich is grounded, through the medium o~ a resistor R14, of a Schmitt trigger circuit BS2 and of a differential circuit CD2~ The Sch~itt trigger circuit BS2 and the differen~ial circui-t CD? have the same cons-tructiorsas the Schlnitt trigger circuit BS1 and the differential circuit CD1, 30 respectively. The inverters IV49 IV5 and the resistor R15 correspond to the inverters IV2 and IV3 and to the resistor R6, respectively. The differential circuit CD2 accordingly comprises a capacitor C8, a resistor R17 and a diode D4 which correspond to -the capacitor C69 the resistor R5 and the diode D1, respectlvelyO

As -to the voltage di~ider, it is seen that a resistor R16 may be connected in parallel relation to the resistor R12 through a swi-tching button B2 which is open in its rest position.
The output of the gate P2, which forms a second OUtpllt of the flip-flop BA1, is connected through a resistor R18 -to a switching transistor T2. The emitter of this trans-istor forms a second control output for the generator device GM and is grounded through a resistance R19 and a 10 ligh-t-emit-ting diode DE2 likely to emit a light of green colour.
The part II of the synchroni~ing circuit CS, for making the connection between the transformer-mixer TRM
and the generating device GM, comprises a relay contact rl which is connected between the input E1 of the sy~chron-izing circuit CS and the output S of the latter. In the state of rest, the contact r1 is open and connects the output S to the ground through the agency of a resistor R20. This contact r1 is operated by a relay R which is 20 mounted in the emitter circuit of a transistor T30 A
connec-tion consisting of a resistor R21 and of a light-emitting diode DE3 likely to emit a light of green colour is connected in parallel with the relay R. Moreover, a diode D5 is connected across both terminals of the relay.
The anode of the diode is grounded. ~he -transistor T3 is controlled by a flip-flop BA2. For that purpose, an out-put of this flip-flop is connected to the base of -the transistor T~ through the medium of a resistor R22. A
second output of the flip-flop is connected to a series-30 connection o~ a resistor R23 and of a light-emitting diode DE40 This diode DE4 is emitting a red light. The flip-flop BA2 consists, as the flip-flop BA1, of two NOR-gates ` P3,P4 wi-th two inputs, one input of each gate being connected to the output of the other gate. The free input uf each gate forms a control input of the flip-flop.
The control circuit for the ~lip-flop BA2 comprises a potentiometer P2 which is connected between the input E1 of the synchronizing circuit CS and the ground, a Schmitt trigger circuit sS3 connected wi-th its input to the contact slide of the potentiorne-ter P2 and with its outpu-t to two parallel-connected input circuits each one of which is connected to the free input o~ a ga-te P3,P4. '~he input circuit o~ the gate P3 coMprises a d;f~erential circuit CD3,whereas the input circuit of the ~a-te P4 coMprises a di~ferential circuit CD4 before which is rnounted an inverter switch IV6. The differential 10 circuits CD3 and CD4 have the same const~ctio~sas the dif~erential circuit CD1~ The differential circuit CD3 there~ore comprises a capacitor C10, a resistor R24 and a diode D6u The elements of the differential circui-t CD4 are designated by the reference characters C11, R25 and D7, respectivelyO The Schrni-tt trigger circuit BS3 comprises two inverters IV7 and IV8~ Connected in parallel -therewith is a resistor R~6.
A resis-tor R27 is connected across the slide contac-t of the potentiometer P2 and the input of the Schmitt trigger 20 circuit BS3. It is, moreover, seen that a diode D8 is connected be-tween the slide contact and the ground~ lt is the anode which is connected to -the latter.
The parts I and II o~ the synchronizing circuit CS ~re inter-connected by a diode D9 ~or enabling the part II to act upon the part Io Referring again to Figure 1, it is seen that the system according to the invention also comprises a lolld-speaker HP and a head-receiver or earphone CE which may be connected to the system according -to the invention by 30 means o~ two change-over switches IN6 and INj~
According to the position of the switch IN7, the loud-speaker or the head-receiver may be connec-ted in para]lel with the line section B or instead thereof.
The message-transmitting system according to the present invention, which has just been described, operates as f'ollOW9:

The sending ol a message through the telephone net-work may take place as soon as the swtiches IN1 to IN5 are in ~their positions shown on Fi.gure 1. The beginni.ng of the emission o.~ a message i.s deterrnined by -the synchronizing circuit CS in synchronous relationship with -the arrival of a service signal.
Be~ore the arrival of such a signal Irorn the generator GM and prior to -the closi.ng of the swi.tch button B1, the flip-..flop BA1 of the synchronizing circuit CS is 10 biased so that the output of the gate P1 exhibits a positive potential represen-tative of the logic value 1.
The output of the gate P2 is therefore i.n the 0 state from which follows that the inpu-t of the gate P1, which is connected to that output, is a3so in the 0 stateO. In view of the location of the capacitor C6, the free input of the gate P1 automatically exhibits the value 0. As to the gate P2, in view of its capacitor C8, its free input is in the O condition whereas the other input exhibits the value 1.
Under such circumstances, the transistor T1 is conducting or on and the diode DE1 emits a red light indicating that the message-generating device G~ is off or inoperative.
The transistor T2 is Ofn As to the ~lip-flop or multi-vibrator BA2, i-t is the output of the gate P3 ~hich exhibits the state 10 Both inputs of tl1e gate therefore are in the 0 s-tate owing to the 0 value at -the output of -the gate P4 and to the location of the capacitor C110 The inpu-ts of the gate P4 are in the states 0 and 1, respect-ively. Under such circums*ances 9 the diode DE4 is energized. The transistor T3 is off and the relay R is 30 not energizedO Its contact r1 is open~
By closing the switch button B1 the flip-flop or multivibrator BA1 is made sensitive to the service signals coming .-rom the input E? of the synchronizlng circuit CS.
These sig~als are causing the free input of the gate P1 to pass from the state 0 to the state 1 and thus cause the flip-flop or multivibra-tor BA1 to toggle or to change its stateO The output of the gate P2 assumes the value 1 thereby making the -transistor T2 conducting and providing at the emitter the production of a positive signal which is -transmitted to the generating device GM and pu-ts sar~e onO The generator then starts emitting signals represent-ing the message to be sen-t out. These message signals are causing -the free input of the gate P3 of the flip-flop or mul-tivibrator BA2 to assume the s-tate i thereby resulting in the toggling o~ the multivibra-tor or ~lip-flop BA2, the conduction of the transistor T3, ~the energizing of the relay R and the closing of the contact r1. ~IOnce the latter is closed the message signals from the generator GM
may reach the input E2 of the mixer TRM which receives the service signals at its other input E1. The mixer produces at its output S a mixture of both kinds o~ signalsO The latter may be metered by means of the amplifier device AM
which operates as a clipper-amplifier and by means of the at-tenuator AT. The messages from the generator GM may be of any sui-table character such for instance as musical or advertising messages~ It should be pointed out that9 during the transmission o~ the messages, the gates P2 and P4 of the multivibrators or flip-flops BA1 and BA2 exhibi-t at their two inputs the potential O and at -their outputs the value 10 At the end of the transmission of a message, the free input of the gate P4 returns to the level 1 thereby causing the toggling or change o~ state of the multi-vibrator or flip-flop BA2 9 -the blocking of the transistor T3, the de-energizing of the relay R and the opening of the contact r1 hence the breaking of the connection be~tween the mixer TRM and the message generating device GMo Through the medium of the diode D9, the toggling or change of state of the flip-flop or multivibrator BA2 results in the toggling of the flip-~lop or multivibrator BA1~ The output of the ga-te P1 becomes positive again and this causes the transistor T1 to be conducting or put onO The ~9~315143 positive signal which is generated at the emitter of the latter will switch off the generating device GM~
If it is desired to stop -the generator GM befo-re -the end of a message it suf~ices to close the but-ton switch B2 thereby causing the free input of the gate P2 to pass from the state 0 -to the state 1. The flip~flop or mul-ti-vibrator BA1 changes its state. As just stated, this results in the generator GM being stopped or swi-tched o~f.
It is obvious -that the system according to Figures 1 10 and 2, such as described and shown, may be modified in various ways within the scope of the present invention.
For instance, the mixer could be of any suitable nature.
The synchronizing circuit CS could comprise means causing the generator GM to stop or to be switched off at -the end of a service signal. The generating device GM could comprise any number o~ generators, each one of which is likely to be connected to the -transformer TRG through the agency of a switch 9 as shown on Figure 1.
Figure 3 shows an embodiment of the invention which 20 is adapted to a telematic systemO
As seen on Figure 3, in such a system a subscriber's terminal A is connected through a subscriber's telephone line LT to a central station Bo The subscriber's terminal A comprises a telephone set AT and a data processing device TD adapted to reproduce onto a suitable support -the information or data which may be transmitted to the terminal A by the subscriber's line LT. According to the Figure, the inputs of the telephone set AT and of the data processing device TD are connected to an output 30 of a signal separator SP, respectively7 the input of which is connected to the subscriber's telephone line LT~ The function o~ this separator is to separate -the accoustic signals adapted to be read out or picked up by the receiver of the -telephone set AT, from the data for instance digit signals to be processed in the device TD~
In the example shown, this data processing device TD
I

essentially comprises a viewing screen EV such for instance as a cathodic screen, a printing device IM such as a printer and a s-torage or memory device ME~ These various devices are connected to a rnodulator--demodulator unit (MODEM) ~)1 performing -the function cf a converter as known in the ar-t.
The storage device ME is adapted to receive series infor-ma-tion and to transmit thern in parallel or in series but possibly with a higher speed of -transmissionO The arrows show the action of the storage device upon the screen 10 de-vices EV and upon the printing device IM~
As to the central station B, there is provided a mixer M bo-th inputs of which are likely to be connected to a service signal genera-tor GS and to a message generator GMo The outpu~ of the mixer is connected to the subscriber's line LT~
According to the present inven-tion, the message generator consists of a device for emitting signals such as data signals likely to be processed in a data processing device such as the device TDofthe subscriber's ~P~;r~1 A, i.e.
20 messages adapted to be reproduced onto a support such as -the viewing or visualizing display screen E'V and/or onto a printing support (printer IM). With possibly the assist~nce o~ a MODEM device,MD2 the information to be sent to the terminal A may be processed so as to correspond in terms of the speed of transmission and of the frequency band width or range to -the da~ta signals normally transmitted by the network~
The message generator GM is operated by a control circuit C under the action,according to the example shown9 30 of two detectors D1,D2 connected to the telephone line between or across the service signal generator GS and the mixer. The detector D1 could perform the function of sensing the presence in the subscriber's line of a service signal for instance of a signal requesting the subscriber using the terminal A after he has unhooked or lifted the handset of i-ts telephone set AT to dial the calling number of the telephone set, sta-tion or terminal with which he wishes to co~nunicate. The detector D2 could be sen.sitive to the end of the step of making the telephone connection and in particular to the mo~ent at which the called subscri ber replies ~or instance by unhooking or lifting his handset. The signal produced by the detec-tor D1 could cause the control circuit C to put the message generator into operation or on, whereas a signal from the detector D2 could cause the generator GM to be s-topped or pu-t off 10 through the medium of the control circuit CO In such a case, the generator GM would emit messages during -the whole step of establishing -the telephone connection until the moment of a positive reply from the called subscriberls -telephone set.
The detectors could, of course, be adapted while being possibly completed with other detectors to accomplish more complex functions and for instance to work in such a way tha~t the generator GM be emi-tting only during the periods o:f absence of service signals or only during 20 certain periods of the line connection establishing s-tep.
It could also be provided that the service generator GS
controls the message generator directly or indirectly, in accordance with the type of service signals it emits as symbolized by the arrowed dashed line.
These various simple or even complex functions for controlling the message generator G~ may be carried out in any known suitable manner~
It should be noted that the service signals consist of periods of presence of oscillations with frequencies 30 of several hundreds of Hertz, for instance between 400 and 500 Hzo These signals may therefore be easily detected or sensed.
It is readily understood -that, under such circum-stances~ the separation of the service signals from the data signals may be easily accomplished by the separator SP of the subscriber's terminal A if the MODEM ~D2 forming a converter associated with the message-generator GM uses carrier frequencies which are sufficiently spaced from the service frequencies.
To complete the description of the rnessage transmitting system shown, this system comprises a co~nuta-ting switch CM1 for short-circuiting the rnixer M
and a co~utating switch CM2 adapted -to cor~ect the -telephone set AT and the da-ta processing device TD
al-ternately and directly to the telephone line LT without 10 the signals being compelled to pass through -the separator SP. As symbolized by arrowed lines, the commutating switch CM1 could be actuated by the control device C in synchronizing relationship with the operation of the message generator GMo The operation o~ the message transmitting system follows from the description of the structure of this system and of the functions the various elements and devices have to perform.
When a subscriber owner of the terminal A wishes to 20 be put in communication -through the telephone or data -transmitting network, with another subscriber's set, station or terminal, which may be a data bank or a for instance b~nkin~ transaction c.enter or any other infor-mation-emitting institution, he unhooks or lifts the hand-set of his telephone set AT r Subsequent to this step, the central station transmi-ts to him several signals requesting him to do the necessary steps for establishing the telephone connectionO According to the functions assigned -to -the detectors D1,D2 which have been set forth herein 30 above, the message generator GM will emit messages of a nature suitable for being reproduced in the subscriber's terminal A from which the call for establishing a telephone connection is originatingO These signals before reaching the mixer M and be~ore being fed into the subscriber's telephone line LT, where they possibly will be superposed to the service signals, will be processed by -the MODEM MD2 to be matched with the properties and capabilities of the ne-twoxk. This processing is, of course, different according as the telephone lines are ordinary or special lines, i.e. consis-ting lor instance of optic fibres or coaxial cables. It is well kno~n that, in this latter case, -the output of binary digi-l;s or bits, i.e. the rate of -transmission or the speed of modulation may be much higher and even make possible the transmission of television signals~ The MODEMs MD1 and MD2 should, 10 therefore~ be designed in accordance with the admissible rate or speed of modulation of the networkO
The system according to the present invention makes possible the data transmission from the message generator GM during the whole period of establishing the telephone connec-tlon.
In the subscriber's terminal A -the data signals, after having been carried through the separator SP, may be viewed or visually displayed dlrectly and immedia-tely on the screen EV or printed by the printing device IM. If 20 the network allows a sufficient rate of transmission9 the c~ll ing subscriber could see for instance a television picture or a text appearing on his screen. I~ the tele phone line does no-t allow a rate of transmission high enough, io e. a binary digit or bit output adequate for a direc-t display as a picture on the screen, the information could be stored in the storage or ~emory ME and trans-mit-ted la-ter for instance at a given time with an adequate output to the screen or to the printerO
It will be understood that the message transmitting 30 system according to -the present invention makes possible a large num~er of applications without ~arting ~r~m theprinciple which has just been stated. In the system according to Figure 3, could of course be used a synchronizer circuit of the kind described with reference to the embodiment shown in Figures 1 and 24 Conversely~ a control circuit or a detection device such as shown and described in relation to the system shown on Figure 3, is usable in the embodiment according to F'i~lre 1 in replaceMent of the synchronizer~ There could thus be provided for the first embodiment, an emission of messages during the perlod of silence bet~Jeen two successive service signals. As a general rule, the means used in one embodimen-t may be incorpora-ted in-to the other embodiment at least in a suitable, practical and possibly equivalent version.

Claims (23)

I CLAIM:

1. In a telephone system, comprising a plurality of subscriber stations each provided with a subscriber terminal including a telephone set, a telephone transmission network, each of said subscriber stations being interconnectible to another of said subscriber stations via said transmission network, serv-ice signal generating means for generating and emitting service signals relating to the establishing of a telephone connection between two subscriber stations, and telephone line means con-necting the output of said service signal generating means to said subscriber stations for transmitting said service signals to a subscriber station emitting a call for the establishment of a telephone connection with another subscriber station, a message transmitting system for transmitting messages to a subscriber station calling for the establishment of a telephone connection during the period of establishing said connection, said message transmitting system comprising message generator means for generating and emitting said messages, service signal -transmitting circuit means, message transmitting circuit means, and a mixer having a first input connectible to said service signal generating means through said service signal transmitting circuit means and a second input connectible to said message generator means through said message transmitting circuit means, said mixer having an output connected to said telephone line means and said mixer, first and second inputs being simultaneous-ly connectible to said service signal generating means and said message generator means.

2. A system as claimed in claim 1, further comp-rising a synchronizing circuit for insuring synchronized emis-sions of service signals and of messages by said service signal generating means and said message generator means.

3. A system as claimed in claim 1, wherein said mixer consists of a transformer with two primary windings and a secondary winding and wherein said primary windings have free terminals acting as inputs of said mixer and a common terminal connected to a point at ground potential.

4. A system as claimed in claim 1, further comprising switch means for connecting said message transmitting system to said telephone line means.

5. A system as claimed in claim 1, wherein said service signal transmitting circuit means connected to said first input to said mixer comprises an amplifier and said message transmitting circuit means connected to said second input of said mixer comprises an attenuator.

6. A system as claimed in claim 1, wherein said message generator means comprises data reproducing means and signal emitting means for emitting signals such as data signals for reproduction at the terminal of a subscriber station calling for the establishment of a telephone line connection to said data reproducing means, said message generator means being con-nected to said second input of said mixer, the first input of which receives the service signals from said service signal generating means, and the output of said mixer being connect-ible to the calling subscriber's station.

7. A system as claimed in claim 2, wherein said synchronizing circuit comprises a first circuit arrangement for the on/off control of said message generator means, said first circuit arrangement being connected to said service signal transmitting circuit means and being responsive to said service signals for detecting the presence or absence of a service signal.

8. A system as claimed in claim 6, further compris-ing separator means for separating the service signals from the signals to be reproduced by said data reproducing means at the subscriber's telephone terminal, said separator means having an input coupled to the output of said mixer and two outputs coupled to said data reproducing means and the telephone set at said terminal, respectively.

9. A system as claimed in claim 6, further compris-ing a control circuit, a first detector sensing the presence of service signals and a second detector responsive to the res-ponse of the called subscriber's terminal after the establishment of a telephone connection between a calling and a called sub-scriber station, said detectors being connected to said control circuit for selectively switching said message generator means on and off.

10. A system as claimed in claim 6, further comprising memory means at the subscrlber's telephone set for storing inform-ation received from said message generator means during the period of making a connection with the called subscriber's tele-phone set and for reproducing said information at any desired suitable time via said data reproducing means.

11. A system as claimed in claim 6, further comprising a modulator-demodulator connected between said message generator means and said mixer.

12. A system as claimed in claim 7, wherein said synchronizing circuit further comprises a second circuit arrange-ment for controlling the making and breaking of a connection between said mixer and said message generator means in accord-ance with the presence, absence and/or end of a message from said message generator means at an input of said synchronizing circuit.

13. A system as claimed in claim 9, further compris-ing a commutating switch for switching said mixer on and off, said commutating switch being operated by said message generator means control circuit in synchronized relationship with the control of said message generator means.

14. A system as claimed in claim 1 wherein the message generator means comprises recording and reproducing means com-prising a recording medium for storing a plurality of messages recorded in digital form.

15. A system as claimed i claim 12, wherein said synchronizing circuit further comprises means for interconnect-ing said first and second circuit arrangements and adapted to cause the generation of a control signal for switching off said message generator means by said first circuit arrangement upon the detection of the end of a message by said second circuit arrangement.

16. A system as claimed in claim 12, wherein said synchronizing circuit further comprises a message receiving input connectible to said message generator means and an output connectible to said second mixer input, a commutating switch connected between said message receiving input and said output and a control circuit for said commutating switch which is res-ponsive to the presence of a message at said message receiving input.

17. A system as claimed in claim 12, wherein said first circuit arrangement further comprises a detector circuit and a bistable multivibrator having two inputs and two outputs, one input being connected to said detector circuit for sensing a service signal for causing the generation of a signal for energizing said message generator means and the other input functioning as the control input for deenergizing said generator means.

18. A system as claimed in claim 14, wherein said recording and reproducing means further comprises analog-to-digital converter means having sampling means for recording messages in digital form.

19. A system as claimed in claim 15, wherein said first circuit arrangement of said synchronizing circuit further comprises control means for stopping said message generator means before the end of a message.

20. A system as claimed in claim 17, wherein said second circuit arrangement of said synchronizing circuit com-prises a bistable multivibrator having one input which is sensi-tive to the presence of a message at the message receiving input of said synchronizing circuit and another input sensitive to the end of a message.

21. A system as claimed in claim 17, wherein said bistable multivibrator comprises two NOR gates each having an output and an input, the output of one gate being connected to the input of the other gate.

22. A system as claimed in claim 20, wherein said second circuit arrangement further comprises a control circuit for a relay, and one input of said bistable multivibrator is connected to said control circuit for said relay and said commut-ating switch is a contact operated by said relay.

23. A system as claimed in claim 20, wherein said bistable multivibrator comprises two NOR gates each having an output and an input, the output of one gate being connected to the input of the other gate.