JPS5818037B2 - button phone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a button telephone used in a button telephone device that connects a key telephone and a main device with three pairs of lines.

A button telephone device is already known in which multiplexing technology is introduced for the purpose of reducing the number of wires between the main device and the button telephone device. A button telephone device that connects to

However, because this 3-pair button telephone device reduces the number of wires, compared to the conventional multi-wire button telephone device, the function may deteriorate or the control circuit for multiplexing is complicated and expensive. First, there was a drawback that the button telephone device as a whole was expensive.

For example, in a button telephone device using a three-pair line, the person who operates the button telephone device has buttons and buttons for setting the voice signal-related parts around the transmitter/receiver and the call route. It can be thought of as consisting of a lamp that displays the results.

(The calling function is omitted here to simplify the explanation.

) And in a button telephone device using 3-pair lines, the call route is set at the crosspoint in the main device,
Furthermore, since the result is known by the main device, the button telephone needs to send and receive button and lamp signals, or signals equivalent thereto, as data to and from the main device.

- Thus, a button telephone can be considered a kind of data terminal with respect to button and lamp signals.

Considering this, button damage can be detected at a speed that does not cause the operator to feel strange about the button operation that is input.
must be processed.

Since a non-locking button is normally used as a button in a button telephone device using a three-pair lock, this condition often becomes a major problem in terms of the processing speed of the device.

That is, for example, in a button telephone device having a 28-button telephone with 12 stations and 2 extensions, the total number of buttons is (12+2).
)X28 = 392 buttons, and on the other hand, it is known that the minimum operating speed of a non-lock button is about 40m5, so the conventional method of sequentially scanning the entire button telephone device one button at a time has no margin. Even without considering the
).

Furthermore, if there is a margin for operation and the size of the key telephone device increases, even faster processing speed is required, and there are cases where processing is performed at a speed of about IMHz, for example.

However, if the transmission speed between the button sleeper main device and the button telephone is required to be as fast as above, the transmission-related rework will be expensive, and on the other hand, by adding buffer memory etc. Even if control and transmission speed are separated, it will still be expensive, and in reality, a method is used that imposes limits on the size of the key telephone device and limits on transmission distance.

. Therefore, a method of scanning each button telephone set in parallel may be considered as a method that can perform sufficient processing while eliminating such inconveniences.

In this system, the conditions for transmission speed are relaxed, so there are fewer restrictions on transmission distance and the size of the key telephone device.

However, if an attempt is made to directly perform parallel processing in the main device, there is a risk that the main device will become more complicated and more expensive.

The present invention has been made in consideration of these points, and provides a button telephone that is suitable for a button telephone device in which control of the key telephones is performed in parallel, and that can also simplify the control circuit of the main device 9. .

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is for explaining the present invention, and for the sake of clarity, the handset side and the calling speaker side of the button telephone are separated, and the terminal circuit in the main unit is also separated into the calling path side and the calling voice transmission path side. It is divided into two parts.

To explain the configuration, 1 and 2 are central lines, and these central lines 1 and 2 are:
It is connected to a call crosspoint 5 via office line circuits 3 and 4.

An extension circuit 6 is connected to this call cross point 5,
This extension circuit 6 is further connected to a paging crosspoint 8 via an extension paging circuit 7.

A central office line paging circuit 9 is connected to this paging crosspoint 8 .

The telephone cross point 5 includes the office line circuits 3, 4,
A terminal circuit 10A selectively connected to the extension circuit 6.

The handsets 13, 14, 15- are connected via 11A, 12A.

On the other hand, the calling cross point 8 has terminal circuits 10B and 1 selectively connected to the office line calling circuit 9 and the extension calling circuit 7.
Call speaker 16.17.1 via 1B, 12B
8 is connected.

Furthermore, the handset 13, 14, 15 and the calling speaker 16.17
．． 18 constitute each button telephone 19, 20, 21, and the other part 22 is the main device.

and the handset 13 of each button telephone 19, 20, 21,
14.15 and the main device 22 are connected by a speech tone transmission line 23,
24°; connected at 25, and call speakers 16, 17
Between ゜18 and the main device 22 is a calling voice transmission path 26゜27.
．． Connected at 28.

Also 19S and 20S. 21S is each button telephone 19,
20.21 button switch, 29, 30.31
is an uplink control signal transmission path.

In addition, 32, 33.34 is each button telephone 19.20
, 21, and the display elements 32, 33, and 34 are configured to be controlled by a signal passed through a downlink control signal transmission path 35°, 36, and 37.

To explain the operation in this configuration, first, in the case of a central office line call, when the button switch 19S selects the central telephone 19, for example, the central telephone 19 selects the central office line 1, and the information of the selected button switch 19S passes up the control signal transmission path 29 to the terminal circuit. 10A to the call crosspoint 5 and control it, thereby connecting the handset 1.3 and the call voice transmission line 2.
3. The terminal circuit 10A1 is connected to the central office line 1 via the telephone cross point 50 point 5a and the central office line circuit 3.

Next, in the case of an incoming call from a central office line, when an incoming signal is given from the central office line 2, the incoming call is detected in the central office line circuit 4, and a preset key telephone, for example, the key telephone 20, is When tone paging is performed, a ring tone is generated from the office line paging circuit 9, and is sent to the paging speaker 17 via the paging cross point 8a, the terminal circuit 11B, and the paging audio transmission line 27, A ring tone is generated.

For this voice call, a call crosspoint 8 is provided that is independent of the call crosspoint 5, and the ringing tone is transmitted through a route different from the call path, so the button telephone 2 that is called is called.
A call can be made even if 0 is busy.

If the key telephone 20 answers here, its handset 14 is connected to the office line 2 via the call voice transmission line 24, the terminal circuit 11A1, the call cross point 50 point 5b, and the office line circuit 4, and a response is made.

At this time, as for the previous station line call, the detection of incoming call on the station line 2 disappears, so the call stops and the call crosspoints 8 and 8a are restored.

Next, in the case of an extension call, for example, if the key telephone 19 makes a call, the handset 13 of this key telephone 19 is connected to the voice transmission line 23, the two-terminal circuit 10A, the point 5C of the call cross point 5, the extension circuit 6, and the extension call. Connected to circuit 7.

If you dial in this state, the called party will be selected.

In the case of MF dialing, this dialing signal can be directly given to the extension calling circuit 9 through a communication path.

Alternatively, the dial signal can be used as a control signal to be transmitted from the key telephone to the main unit through an uplink control signal transmission path and provided to the extension calling circuit 7.

Now, suppose that the called party is the button telephone 20 due to the dialing operation described above.

Here, if a voice call is to be made, the voice from the key telephone 19 is transmitted to the extension call circuit 7 as described above, and then further to the call cross point 80 point 8.
b. The signal is sent to the calling speaker 17 via the terminal circuit 11B and the calling audio channel 27, and a voice calling is performed.

This extension voice call can also be made even if the called party's key telephone 20 is in use.

Note that although the above description is about voice calling, this is not limited to this, for example, if the route is disconnected in the extension calling circuit 7,
Tone calling can also be performed by sending a ringback tone to the calling party and a ringback tone to the called party.

In addition, in the above-mentioned voice call, by adding a band-free response procedure that has the functions of a calling speaker and a microphone instead of the calling speaker 17 of the called party's key telephone 20, it is possible to receive a call from the calling party's key telephone 19. It is also possible to use the line up to the caller's key telephone 20 in both directions for calling and band-free response.

Next, the case of an extension call will be explained.

It is assumed that an extension call is made as described above and that the call is answered.

As is typical for button telephone devices, responses can be made even from a button telephone, so here we will use, for example, button telephone 2.
The case where 1 responds will be described.

That is, the handset 15 of the button telephone 21 is connected to the call voice transmission line 25, the terminal circuit 12A, the call cross point 50 point 5d, and the extension circuit 6, and is connected to the caller's key telephone 19 via the call cross point 5. and is connected in parallel to the extension circuit 6.

At this time, the calling of the extension is stopped, the connection between the extension circuit 6 and the extension calling circuit 7 is cut off, and the point 9b of the calling crosshair point 8 is restored.

In this way, calls between extension lines can be made.

In addition, the display element 3 on each button telephone 19, 20, 21
2, 33, and 34 are terminal circuits 10B and 11B that pass through a display signal control circuit (not shown).

112B, and is transmitted to the downlink control signal transmission path 35°36.
37 to the display elements 32, 33, and 34 of the button telephones 19, 20, and 21, and are turned on or blinked at a predetermined period depending on the central office line and each internal state.

[Next, the configuration of the button telephone according to the present invention and the connection state with the main device will be explained with reference to FIG.

Here, the key telephone 19 shown in FIG. 1 will be taken out and explained.

The handset 13 of the button telephone 19 has a handset 13a and a handset 13b, each of which has a receiver amplifier 41a.
and a sidetone prevention circuit 41c via a transmitting amplifier 41b, and this sidetone prevention circuit 41e is connected to a transformer 42.

The other winding of the transformer 42 is connected to the transformer 81 of the terminal circuit 80 of the main device 22 via the speech voice transmission line 23 of the three-pair line 70.

41d is a touch tone dial transmitter, which is connected to the input terminal of the transmitter amplifier 41b.

The button switch 198 includes a hook switch 19Sa and other line selection switches 19Sb and 19Sc, each of which is connected to a parallel-to-serial conversion circuit 43a for multiplexing. It is connected to the control end of amplifier 41b.

The output end of the parallel-to-serial conversion circuit 43a is connected to an uplink control signal sending circuit 43b, and this uplink control signal sending circuit 43b is connected to a transformer 44, and the other winding of the transformer 44 is connected to the uplink control signal sending circuit 43b of the three-pair line 70. It is connected to the transformer 83 of the terminal circuit 80 of the main device 22 via the signal transmission path 29 gh.

Further, the call speaker 16 is connected to a transformer 46 via a call amplifier 45, and both ends of the other winding of the transformer 46 are connected to the midpoint of the winding on the 3-pair TO side of the transformer 42.44. The midpoints of the same windings of transformer 46 are connected to the power supply circuit 470 input terminal.

In addition, the display element 3 such as a light emitting diode of the button telephone 19
2 is connected to a serial/parallel conversion circuit 48a, and one output terminal of this serial/parallel conversion circuit 48& is connected to the control terminal of the calling amplifier 450.

The input end of this serial/parallel conversion circuit 4B& is connected to the output end of the downlink control signal receiving circuit 48b, and the input end of this downlink control signal receiving circuit 48b is connected to the transformer 49.

The midpoint of the other winding of this transformer 49 is the power supply circuit 4
7, and both ends of this winding are connected to the transformer 84 of the terminal circuit 80 of the main device 22 via the down control signal transmission line 35 of the three-pair line 70.

The terminal circuit 80 includes two terminal circuits 10A and 10B shown separately in FIG.

In the main device 22, one winding of the transformer 81 of the terminal circuit 80 is connected to the communication crosspoint 5, one winding of the transformer 83 is connected to the uplink control signal receiving circuit 85, and one winding of the transformer 84 is connected to the uplink control signal receiving circuit 85. The line is connected to a downlink control signal sending circuit 86.

A clock synchronization generation circuit 300 is connected to this downlink control signal transmission circuit 86.

Furthermore, a transformer 82 is provided by connecting both ends of one winding to each midpoint of the windings on the three-pair line 70 side of transformers 81 and 83, and the other winding of this transformer 82 is connected to the calling cross point 8. be done.

Further, a DC power supply 87 is connected between the midpoint of the winding of the transformer 82 on the side connected to the transformer 81, 83 and the midpoint of the winding on the side of the pair line 70 of the transformer 8403.

FIG. 4 shows the downlink control signal sending circuit 86 in the above configuration.
3 shows the circuit configuration of the downlink control signal receiving circuit 48b.

In the same figure, the downstream control signal sending circuit 86 first introduces the clock signal a generated from the clock synchronization generation circuit 300 into the gate 129 and guides it to the gate 130 via the inverter 127.
．． The synchronization signals generated by the clock synchronization generation circuit 300 are respectively introduced to the clock synchronization generating circuit 300.
, 130 output the original waveforms of positive and negative pulses of a downlink control signal d, which will be described later.

Then, the clock outputs of these gates 129 and 130 are combined by resistors 139 and 140 via a buffer 135 and an inverter 136, respectively.

Therefore, there is a state where there is no control signal C, which will be described later, that is, tt
][, the downlink control signal d at the pp level is obtained.

Further, the downlink control signal sending circuit 86 outputs the control signal C as
131, 132, where the gates 129,
The clock output from 130 is passed only during the (.H# level period of control signal C), and these passing clock outputs are combined by resistors 137 and 138 via buffer 133 and inverter 134, respectively.

Then, this combined control clock output and the resistor 13
9 and the clock output synthesized at 140,
This synthesized clock output is used as the downlink control signal d, and the DC component is removed by the capacitor 141, and then the transformer 84
The signal is sent to the downlink control signal transmission line 35 via the.

Resistor 42 here performs a matching function. On the other hand, the downlink control signal receiving circuit 48b amplifies the downlink control signal d input through the transformer 49 with the amplifier 144, and the level determination circuit 14
5,146 respectively.

Note that the resistor 143 performs a matching function.

The level discrimination circuit 145 has a positive high threshold level L0 and separates the control signal e.

On the other hand, the level determination circuit 146 has a positive low threshold level L2 and separates the clock signal f.

Further, the downlink control signal receiving circuit 48b transmits the clock signal f separated by the level determination circuit 146 to the inverter 14.
After being inverted at 7, it is connected to capacitor 150 via resistor 149.
This capacitor 150 is charged.

Then, the level of the charging voltage of the capacitor 150 is determined by a level determining circuit 151, and when the voltage falls below a certain value, an output corresponding to a synchronizing signal is generated.

The operation of such a configuration will be described with reference to the operation waveform diagram of FIG. 3.

First, the power supply for the button telephone 19 is powered by the power supply 8 in the main device 22.
The signal reaches the power supply circuit 47 from the terminal circuit 80.

Of course, those that do not require stabilization may be supplied as they are.

To explain in more detail here, the power supply path in the three-pair line 70 is as follows:
Enter from the midpoint of 2 and continue from both ends of the transformer 81.8
14 currents flow in parallel from the midpoint of 3 to each line of the 3-pair line 700, the speech voice transmission line 23, and the uplink control signal transmission line 29.
It enters from both ends of the transformer, exits from the midpoint, enters both ends of the transformer 46゛, exits from the midpoint, and connects to the power supply circuit 47.
to go into.

The return path enters the midpoint of the transformer 49 from the power supply circuit 47,
A false current flows through each line of the down control signal transmission line 35 of the three pairs of lines 70, enters from both ends of the transformer 840 in the terminal circuit 80 of the main device 22, and returns to the power supply 87 from the midpoint.

As described above, power is supplied to the three-pair line 7.
If each part of 0 and the midpoint of each transformer are balanced, then
Even if the power supply current pulsates, it does not affect the output generated across each transformer.

Furthermore, if the line length becomes too long and power supply becomes impossible, an external power supply can be installed instead of power supply from the three-pair line 70 to the button telephone 19 to receive power directly. is possible.

Next, we will discuss lock signals and synchronization signals, which are necessary for modulating and demodulating multiplexed button and lamp signals.

Generally, in a button telephone device, the wiring length between the button telephone and the main device is several hundred meters at most.

Therefore, if an appropriate lock frequency is selected and the clock timings are synchronized between the key telephone and the main device, the signals transmitted as downlink control signals and uplink control signals will be transmitted between the key telephone and the main device. Timing (can be considered consistent.

In reality, measures such as using strobe pulses for line and other delays are also used.

For this purpose, in the main device 22, the clock synchronization generation circuit 300 supplies the lock signal a synchronization signal 5 as shown in a and b in FIG. 3 to the downstream signal sending circuit 86.

The clock and synchronization generation circuit 300 supplies common lock and synchronization to the entire main device 22.

Now, the downlink signal sending circuit 86 is further given the downlink control signal C, and transmits it via the transformer 84 to the downlink control signal transmission path 35 of the 3-pair line TO, with the waveform shown in FIG. 3d, that is,
The clock signal is a pulse train that alternately exhibits positive and negative polarities, and a waveform consisting of a synchronization signal, which is indicated by the absence of this clock signal, and a control signal, which is indicated by an amplitude smaller than that of the clock signal, is sent out as a downstream control signal d.

Note that the synchronization signal indicated by the absence of the clock signal is the synchronization signal indicated by the absence of the clock signal, as shown in FIG.
The Lpp level period is used as a synchronization signal.

In the button telephone 19, for example, the waveform d in FIG.
On the other hand, if a signal is detected at level L2, a synchronization signal having a waveform can be obtained by detecting the clock signal f and the absence of the clock signal.

At this time, the extraction of the synchronization signal is carried out by using a time constant circuit consisting of a capacitor 150 and a resistor 149 to detect discontinuities in the reproduced clock signal f, and the output of this time constant circuit being constant, as described in FIG. This is done by detecting with the level determination circuit 151 which detects that the voltage drops below the value.

With this clock signal and synchronization signal, the timing of the serial/parallel converter 48 & for the downlink control signal and the parallel/serial converter 43a for the uplink control signal are controlled.

As an example, the clock frequency is 2400 Hz and the clock period is about 400 μSee, whereas the delay due to the circuit and line is about 50 μSee with a line length of 300 m. Therefore, the main device and the key telephone operate with the same clock and synchronization. It can be considered that

Next, the downlink control signal will be described.

Necessary signals in the button telephone are a blinking signal for the display element 32 such as a light emitting diode and a control signal 90 for the call amplifier 45.

Incidentally, the display element 32 such as the light emitting diode is installed corresponding to each office line and extension line.

Figure 3 shows the timing of multiplexed transmission. T1 is the timing of the central line Ch1, and KT2 is the timing of the central line Ch1.
Assign the timing of 2, etc.

Although FIG. 3 is an explanatory model with a small number of timings, Table 1 shows examples.

That is, 32 clocks constitute one cycle (one frame), and the cycle is indicated by four clocks stopped.

Here, 20 office lines and 4 extension lines are assigned to each timing, and the remaining 4 timings are used for special purposes.

The fact that a common timing is assigned to uplink control signals and downlink control signals for each office line and extension line is not obvious when just talking about downlink control signals, but when looking at key telephones or equipment as a whole, uplink There is an advantage that signals related to both control signals and downlink control signals can be used in common.

In addition, especially in button telephones, the buttons and display elements are used in pairs for each office line and each extension line, so the fact that the timings are assigned in the same order means that the timings can be shared if necessary. It is convenient for doing so.

For example, suppose that a downlink control signal such as waveform e in FIG.

The downstream control signal sending circuit 86 generates the waveform d in FIG.
The signal is sent to the downlink control signal transmission line 35 of the three-pair line 70 as a signal such as .

Then, in the button telephone 19, the down control signal receiving circuit 48b receives the level L1 at the waveform d in FIG.
When the signal is detected, a downstream control signal as shown in waveform e is obtained.

This is demodulated by the serial/parallel converter circuit 48&, and the display element 32
It provides a control signal for the lighting and ringing amplifier 45.

In the example of waveform C in FIG. 3, the display elements of the station line CH1 and station line CH3 are lit.

The display element 32 may be controlled to blink at IHz or 2Hz, but in this embodiment, one period (one frame) is 32 clocks of 2400Hz, or 75Hz, which is sufficient for blinking control at IHz or 2Hz. I can handle it.

Furthermore, one period of 75 Hz means that when controlling the lighting of the display element, the circuit can be simplified by outputting, for example, only 8 clocks per period instead of performing complete demodulation of 32 clocks per period. 75Hz blinking has the advantage that it can be regarded as continuous lighting even if the lighting is changed.

Regarding the uplink control signal, each office line button and extension button hook switch are multiplexed by the parallel-to-serial conversion circuit 43a as shown in Table 1, and are output to the uplink control signal sending circuit 43b as a signal with waveform i in FIG. 3, for example. It is further synthesized with the clock signal f extracted from the downlink control signal, and is output as a signal such as waveform j in FIG. 3, which has mutually positive and negative polarities only when the control signal is present.

This signal j is transmitted to the main device 22 via the transformer 44, through the upstream control signal transmission path 29 of the 3-pair line 70,
In the main device 22, the signal enters the upstream control signal receiving circuit 85 via the transformer 83 of the terminal circuit 80, where the signal is detected and outputs an upstream control signal.

The example of waveforms i and j in FIG. 3 shows that the button and hook switch signals of the central office line CH2 are transmitted as uplink control signals.

Furthermore, it has already been stated that the clock and synchronization of the above uplink control signals can be considered to be consistent with the clock and synchronization within the main device.

Inside the main device. The processing of upstream control signals has become extremely easy.

Now, the above transmission speed of the uplink control signal is sufficient for the button operation speed.

In other words, one period of the multiplexed signal is 75 Hz, approximately 13 ms, and a button.

It is calculated that the uplink control signal will be generated at least three times compared to the minimum operation time of 40 ms.

Next, we will discuss telephone calls using key telephones.

By going off-hook, turning on the hook switch 198a, and operating the central office line or extension buttons 19Sb and 19Sc, the call voice cross point 5 in the main device 22 is connected, and the button telephone 19 is connected to the desired central office line or extension. be done.

First, the receiving amplifier 41a and the transmitting amplifier 41b are powered on and activated by the hook switch 19Sa.

Therefore, in a state where a communication path is established, the voice signal of the other party (or dial tone, busy tone, etc.) passes through the communication voice cross point 5 of the main device 22, passes through the transformer 81 of the terminal circuit 80, and is transmitted to the third party. Pair line 700, voice transmission line 23, and transformer 42 of button telephone 19
The signal is transmitted to the sidetone prevention circuit 41c, the receiver amplifier 41a, and the receiver 13a of the handset 13, and is converted into voice.

On the other hand, the voice of the operator of the button telephone 19 is conversely transmitted to the handset 1.
The signal is converted into an electric signal by the transmitter 13b of No. 3, and is sent from the transmitting amplifier 41b to the three-pair line 700 speech transmission line 23 through the sidetone prevention circuit 41c and the transformer 42.

This telephone circuit network includes a transmitting amplifier 41b, a receiving amplifier 41
a. It is constituted by a sidetone prevention circuit 41e, but unlike a normal telephone circuit network, each amplifier 41a.

41b is inserted to compensate for the loss of the transformer 42 and transformer 81 in the speech transmission path, and by using the amplifiers 41a and 41b, the sidetone prevention circuit 41c is a resistive hybrid circuit. This can be achieved with

Furthermore, the transmitter 13b is powered directly from the communication line in a normal telephone, but in this button telephone, power is supplied from the power supply circuit 47 because the communication voice transmission line is transformer-coupled.

Next, let's talk about the dial.

The button telephone in this embodiment is a touch tone type MF.
It is for dial only.

Touch tone dial oscillator 41d of button telephone 19
The MF multiplied signal is generated by operating the dial button, and this signal is added to the transmitting amplifier 41b, and thereafter transmitted through the same route as a normal audio signal.

Let's talk about calling a button telephone.

When the button telephone 19 receives a call via a central office line call or an extension call, the main unit 22 closes the necessary points of the paging cross-point 8 to configure a path for the calling voice, and also sends a downlink control signal C to the button telephone 19. , the signal of the calling amplifier ON at timing A25 in Table 1 is given.

Then, as described above, the downlink control signal is demodulated by the serial-to-parallel conversion circuit 48 & of the button telephone 19, and the control signal 90 is applied to the paging amplifier 45 to turn on the power and start the paging amplifier 45.

On the other hand, the call voice is transmitted from the call cross point 8 of the main device 22, the transformer 82 of the terminal circuit 80, and further through the midpoint of transformers 81 and 83 to the call voice signal transmission line 23 of the three-pair line 70 and the uplink control signal transmission line 29. is transmitted by configuring a Shigenobu transmission line to
Further, the signal is transmitted to a call amplifier 45 through a transformer 46, and a call is made by a call speaker 16.

Since the route for making a call is completely unrelated to the call route, the key telephone 19 can receive a voice call even during a call.

In addition, in this calling operation, in the case of an extension voice call, instead of the calling speaker 16 and the calling amplifier 45, a speaker and a microphone, as well as a sending amplifier 41b, a receiving amplifier 41a, and a sidetone prevention circuit connected to the calling audio transmission line are used. By providing a circuit corresponding to 41c, it becomes possible to send a reply to the caller from the paging voice transmission line using the microphone.

If no operation is required on the key telephone 19 to make this reply, a function called hands-free answerback has been realized.

Furthermore, when switching between the one-way speaker call described above and the case where two-way response is possible, the switch is made by applying a two-way call signal at timing A26 in Table 1.

Next, the special function portion of the uplink control signal shown in Table 1 will be described.

The office line or extension buttons 19Sb and 19Sc are lock buttons.

Therefore, memory is required to hold the call crosspoint 5.

This memory is located within the main device 22.

Now, to release the hold on this call crosspoint,
If you go on-hook, the state of hook switch 19Sa will change.

It is transmitted to the main device as an upstream control signal to release the sled and thus open the call cross point.

Now, for example, if the button telephone 19 is in the middle of a call to the central office line CH1 and you wish to switch to a telephone call to the central office line CH2,
All you have to do is go on-hook again and operate the button for the off-hook/later station line CH2, but if switching could be achieved by simply pressing the button for the station line CH2, the operability would be much improved.

For this purpose, in the above example, an on-hook/off-hook signal may be automatically given when the button of the central office line CH2 is pressed.

Adding such logic is possible on the key telephone side as well as on the main device side.

Furthermore, in order to improve operability, for example, conventional multi-wire button telephones have a mechanism in which either button operation or off-hook can be performed first. One-handed operation called off-hook is possible.

In this respect, this kind of operation can be made possible even in a main button telephone by adding an appropriate circuit.

In other words, a pseudo off-hook state can be created by operating a button.

Now, although the circuits described above are not shown in FIG. 2, based on this idea, we will discuss the special function tie, Mink A25, 26, and 27 of the uplink control signal in Table 1.

This is all true for conventional multi-wire key telephones.
This is a signal that is sent to the line, but in this button telephone, due to the distribution of logic circuits with the main device, it is sent out in three separate signals.

First, the common key signal A27 is generated as the above-mentioned hooking signal that performs on-hook-off hook when switching button operations.

Further, A26 is generated when the secret conversation release button is operated.

Further, when the hold button is operated, the A26 signal is first sent out, and then the A27 common key signal is also generated.

In other words, the logical AND of the A25 switch and the A27 common key signal corresponds to the signal given to the H line in a conventional multi-wire key telephone, and the A26 hold/
The deprivation signal corresponds to applying an intermediate voltage to the H line.

The above-mentioned control signals are sent to the main device as upstream control signals, and necessary control processing is performed.

As mentioned above, this button telephone has a reduced number of 3
Although it uses a paired line, it has the same features as before, including a blinking display on the display element, line selection using the office line and extension buttons, calls using the handset, calling using the paging speaker, button interlocking, and the ability to cancel calls on hold and privacy. It can provide functions similar to those of a multi-wire button telephone.

That is, compared to the conventional multi-wire type button telephone, the button telephone of the present invention has a multi-wire type in its basic functions when viewed as an interface between the operator and the device in a button telephone/wo-button telephone device. ``2223ka m'v*□, 78u,
Yo.

. By applying this technology, five independent transmission paths are provided, and a call voice transmission path and a call voice transmission path are provided separately, making it possible to receive a voice call even during a call.

Furthermore, since the requirement for high transmission speeds seen in conventional button telephone devices using 3-pair lines has been relaxed, the operating speed of the control circuit in button telephones has also been relaxed, making it simpler and easier to use. This makes it possible to adopt a control circuit that is flexible.

Furthermore, as shown in Table 1, by assigning the same multiplexing timing to each office line and extension line without distinguishing between uplink control signals and downlink control signals, the same format is used for multiplexing modulation and demodulation. This makes it possible to simplify the control circuit not only in the Apotan telephone, but also in the main unit, since the timing can be made common to the whole key telephone device.

As described above, according to the present invention, it is possible to make a voice call during a call by providing a call voice transmission line and a call voice transmission line separately while using three pairs of lines, and to transmit control signals between the main device and the main device. It is possible to provide a button telephone set in which the transmission speed can be relaxed, all control signals are multiplexed using the same timing pulse, and the circuit configuration for control including the main unit is significantly simplified.

Brief explanation of the drawings - Fig. 1 is a configuration diagram showing a button telephone device using a button telephone according to the present invention, and Fig. 2 shows a connection state between a key telephone according to an embodiment of the present invention and a main device. Configuration diagram shown, 3rd
This figure is an operating waveform diagram of the apparatus shown in FIG. 2, and FIG. 4 is a circuit configuration diagram showing the main part of the configuration shown in FIG. 2.

1.2... Office line, 3, 4... Office line circuit, 5... Call cross point, 6... Extension circuit, 7... Extension calling circuit, 8... Calling cross point. 9... Office line calling circuit, 10A, 10B, 11A, 11B, 12A, 1
2B1...Terminal circuit, 13,14,15...Handset, 16°17.18...Call speaker, 19,20.
21... button telephone, 19S, 20S, 21S...
・Button switch, 22... Main device, 23, 24.2
5... Call voice transmission line, 26, 27.28... Calling voice transmission line, 29, 30.31... Uplink control signal transmission line, 41, a... Speech amplifier, 41b... - Receiving amplifier, 41c... Sidetone prevention circuit, 43a... Parallel-serial conversion circuit, 43b... Uplink control signal sending circuit, 45
... Calling amplifier, 47... Power supply circuit, 48a...
Serial-to-parallel conversion circuit; 48b... Downlink control signal receiving circuit; 70... 3-pair line; 86... Control signal sending circuit; 300... Clock synchronization generation circuit.

Claims (1)

[Claims] 1. Five independent transmission lines are configured between the main device and the main device using heavy-duty transmission: a call voice transmission line, a calling voice transmission line, an uplink control signal transmission line, a downlink control signal transmission line, and a power supply line.3 In a button telephone connected by a paired line, a handset and receiver connected to an excitation voice transmission line;
A paging speaker provided connected to the paging voice transmission path and a downlink control signal provided connected to the downlink control signal transmission path and tied by a predetermined timing signal from a main device car are received. a circuit for converting the output signal of this circuit into a parallel signal to control the display element and turning on the signal supply to the calling speaker; means for obtaining an uplink control signal multiplexed according to a timing signal from the main device obtained by a signal receiving circuit; and sending the uplink control signal obtained by this means to the uplink control signal transmission path. A button telephone, comprising: a circuit; and a power supply circuit connected to the power transmission path and supplying power to each of the circuits.