JPS5834074B2 - Holding method for button telephone equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a key telephone device, and more particularly to a central line hold system that operates in conjunction with a ring key of a calling device of a key telephone device.

When using a conventional key telephone to make a direct call to an extension by pressing the telephone key provided on the calling device while talking on a central office line,
In the past, once you connected the central office line, you pressed the hold key on the telephone,
After putting the central office line on hold, the user presses the telephone key to make a call.

However, in this case, the operation is required twice, which is inconvenient to handle and causes operational errors.

In order to eliminate this inconvenience, when you press the dialing key,
There is also a method of mechanically moving the telephone holding key in conjunction with this to hold the central office line, but this method has a complicated structure, is large, and has the drawbacks of lacking reliability.

In order to solve these drawbacks, the present invention provides a hold system for a button telephone device that uses an electronic circuit to automatically put the central office line on hold when the calling key is pressed. This is what we provide.

This will be explained in detail below using the drawings. FIG. 1 is a block diagram showing the entire key telephone device related to the present invention,
co, i...CO, n is a central line, 100-1.・・・'
10Q-n are office line circuits provided corresponding to office lines, each of which is connected to the data highway DH.

200-1...200-n are telephone devices-1,
. . . A telephone-compatible subscriber circuit connected to TEL-n.

TMC is 100-1...100-n-200-1...
- A common circuit that generates control signals for controlling 200-n.

NET in the premises is a telephone call circuit, CU is a telephone control circuit, and SP
is a speaker circuit.

DSS-T is a calling device used in the present invention, and CU' is its control circuit.

DSS- is the main device side control circuit of the calling device.

Hereinafter, in order to explain the operation of the present invention in detail, in FIG.
) and [CU' 2b-)DSS-Kla-+position-n spi b ] route circuit diagrams are shown in Figure 2, Figure 3, Figure 4.
As shown in the figure.

Fig. 2 is a circuit diagram of the basic system of the present invention and a ringing tone sending circuit, Fig. 3 is a control circuit on the main unit side that performs lamp display in addition to Fig. 2, and Fig. 4 is a circuit diagram of the above-mentioned above. This is a circuit diagram of the telephone side.

FIG. 2 is a circuit diagram for controlling the method of the present invention,
1, 27 are counters, 2, 26 are clock pulse generators, 3, 4, 28, 62 are decoders, 5.10, 67.9
1 is an inverter, 8,11°14.31,71,72,
54, 55, 60° 61. 75, 86 are and gates,
7,9,12゜32.56,57,76.81 are OR gates, 13.58.59 are shift registers, 53 is encoder, 68 is multi-by-break 69 is sine wave oscillator for sound source, 65, 66 are analog gates , 77.78 is a transformer, 79 is an amplifier, 80 is a speaker, 82, 83
, 84 is a contact for the calling telephone key, 87 is a common contact that operates when the central office telephone key is pressed, 74 is a delay circuit, 36 is a hook switch, 33 and 34 are contacts for the telephone key for selecting the central office line, 35 is a power supply, 37, 88°89.90 is cable, 40,51,
52, 63° 64. 70, 73, 85 are flip-flop circuits, ■ indicates the (mountain side) side of the power supply, E indicates the side opposite to the power supply.

Further, 1a is a main device side control circuit of the calling device, and 2a is a subscriber circuit of the calling telephone, and a plurality of subscriber circuits are connected in parallel via an OR gate 76 and connected to 1a.

Further, 1b is a calling circuit of the called telephone, 2b is a control circuit of the calling device, and 3b is a control circuit of the calling telephone.

Here, in order to operate the above circuit, first, the counter and 27 are replaced by the clock pulse generators 2 and 26, respectively.
, and further assume that they are synchronized.

For example, when the user raises the handset and presses the telephone key to make a call to the central office line, contacts 33 and 36 become connected.

As a result, the timing pulse (decoder 28 → contact 33 → OR gate 32 → AND cable 1-31 → cable 37 → flip-flop 40) of the output signal T' from the decoder 28 driven by the output signal of the counter 27 is routed. is applied to the input terminal of the flip-flop 40.

As described above, a signal for selecting a central office line, etc. has been sent from the telephone 3b to the main device 2a.

The sent signal is received by the main device 2a and stored in the shift register 3.

Here, the timing for manipulating the shift register 3 will be explained.

First, the counter 1 is constituted by a plurality of cascade-connected binary counters, and is driven by a clock pulse train CP which is the output of the digital pulse generator 2.

A time chart of the outputs C1...C1o of the counter 1 is shown in FIG.

Next, decoder 3 and decoder 4 are driven by the output of the counter, and the respective outputs t,...t,T,...T
get.

Here, T1...T is a signal whose pulse width is the period of the output CtO of the counter, as shown in FIG.

Moreover, as shown in FIG. 5, tl...t is a signal whose pulse width is the period of CP, and compared to the pulse width of T1...T, the pulse width of t,...t is It's small enough.

Furthermore, signals T'1...T' and T1...T from the telephone
There is a relationship between n and n as shown in FIG. 5, 2 and 3, and they are synchronized with a certain delay.

FIG. 51 is a diagram showing the data timing in the case of five office lines, and in the figure, LK1...LK5 indicate signals for the office line telephone keys, respectively.

Further, T indicates a unit time in which T1 . . . Tn are time slots.

As is clear from this figure, the transmission signal T'9 from the telephone set to the main unit is delayed by a certain period of time with respect to T.

This delay is for correcting the synchronization difference between the counter and the counter 27 by receiving the signal near the center of the pulse width when the main device receives the signal.

In FIG. 2, the flip-flop 40 is of a type that outputs an output at the rising edge of the gate pulse C1o.

Therefore, as described above, when the input signal T' is applied here, it is output to the output side of the flip-flop 40 in synchronization with the gate pulse CtO, and is applied to one of the input terminals of the AND gate 11.

The output signal at this time is synchronized with CtO.

Here, C1o is the output of counter 1.

Next, the shift register 13 outputs [output terminal of shift register 13 → AND gate 14 → OR gate 12 →
A feedback loop is formed by the input terminal of the shift register 13, and the shift register 13 is shifted by the clock pulse CP, and the information manually input there is circulated at a constant cycle.
configured to be remembered.

Therefore, in order to manually input the signal to the shift register 13,
A timing pulse is output from the OR gate 9 by a circuit constituted by an AND gate 8 and an OR gate 7.9, and one of the output signals is applied to the AND gate 14 through an inverter 10 to close it.

The other is applied to the AND gate 11 to open it, thereby inputting the signal being applied from the flip-flop 40 to the shift register 13 through the OR gate 12.

Here, this manual timing is t and t2 according to the above.
Therefore, the storage position in the shift register 13 is also fixed, and the signal is output at timings tl and t2 one cycle later.

Here, in order to synchronize the manual power and the output of the shift register 13, the storage capacity of the shift register 13 is set to be equal to the steps t1...tn of one cycle of the decoder 3.

As described above, the office line signal T'9 input from the telephone is converted into timings tl and t2, which are further applied to one of the input terminals of AND gates 54 and 55 via OR gate 76.

Next, in the above state, when the telephone key is pressed to make a call from the calling device DSS-T (2b in FIG. 2) and the contact 82 becomes connected, at this time 82 and 84 form interlocking contacts. By doing so, 84 also becomes a contact.

As a result, the timing pulse T'2 of the output signal from the decoder 28 driven by the output signal of the counter 27 flips through the route of [decoder 28 → contact 82 → OR gate 81 → cable 88 → flip-flop 51]. The flop 51 is set at timing T3, and its output is encoded by the encoder 53.

Here, the timing for inputting the signal obtained by the encoder 53 to the shift registers 58 and 59 is the same as the operation for storing it in the flip-flop 40 described above, and the signal input to the flip-flop 51 is transferred to the shift register 58 and 59. It is output to the output side and applied to one of the input terminals of AND gates 54 and 55.

The output signal at this time is synchronized with C1o. Here, CI
O is the output of counter 1.

Next, the shift registers 58 and 59 output their outputs [output terminals of shift registers 5B and 59 → anime controllers 0 and 6].
1 → Or gate 56, 57 → Shift register 58° 59
The shift registers 5B and 59 are shifted by the clock pulse CP, and the information manually entered there is circulated and stored at a constant cycle.

Therefore, in order to input the signal to the shift registers 58 and 59, a timing pulse obtained from the output side of the above-mentioned OR game 176 is applied on one side to the opposite game 1-60 and 61 through an inverter 67 to close it.

On the other hand, the signal applied from the encoder 53 is applied to the shift registers 58 and 58 through the OR gates 56 and 57 by opening them.
59 manpower.

Here, since this manual timing is determined to be the timing stored in the shift register 13, that is, tl and t2, the storage position in the shift register 58, 59 is also fixed, and t7 after - period. It is output at timing t2.

Here, shift registers 58, 59 and shift register 13
In order to obtain a cycle of , the storage capacity of each shift register is set to be the same.

As a result of the above, T'2 manually entered from the calling device DSS-T
The calling signal is stored in the shift registers 58 and 59 at the same timing as the office line signals tl and t2, and in the form of a code indicating individual information such as a contact point 84.

Here, and gates 54, 55, or gates 56, 57
, shift registers 58, 59, AND gates 60, 61
Two of each are shown, but in actual design, the necessary number of them will be connected in parallel.

Next, in the operation described above, if the contact 82 continues to be connected, the contents stored in the shift registers 58 and 59 are retained.

However, when it is disconnected, the contents of shift registers 58 and 59 are erased.

Therefore, even if the contact point 82 is disconnected, that is, the user stops operating the calling telephone key, the calling continues, and the shift register 5 responds to the callee's response.
A means for erasing the contents of 8 and 59 is required, and its configuration and operation will be explained below.

In Figure 2, 70, 71, 72, 73, 74, 91° 75
This is the circuit constructed by

Here, when one of the calling telephone keys is pressed on the calling device DSS-T, the common contact 84 is connected together with the contact 82 of the calling device DSS-T, and the output signal T'5 ( The υ timing pulse is [decoder 2
8 → contact 84 → OR gate 81 → cable 88 → flip-flop 70] route to flip-flop 70
It is set at the timing of CtO, and its output is synchronized to T5.

Therefore, the output signal is extracted by the AND gate 71, and only the timing pulse of T5, that is, the timing pulse of T'5 is extracted, and the flip-flop 73 is set. It is applied to one input terminal of AND gate 75 and blocks the output of AND gate 75.

As a result, the timing pulse for writing into the shift registers 58 and 59 is not manually applied, so no rewriting operation is performed.

Therefore, even if the telephone key operation on the calling device DSS-T is stopped and the contact 82 is disconnected, and the state of the flip-flop 51 changes, the information will not be manually input to the shift registers 58 and 59, and the contents will remain in the above-mentioned cycle. It is circulated by a circuit to maintain its contents.

Through the above operations, the calling continues even after the telephone key operation on the calling device DSS-T is stopped.

Although it is omitted in FIG. 2, the called telephone 1b has 3
A subscriber circuit S for the called telephone includes a circuit similar to b.
U B-n includes a circuit similar to 2a.

Further, the subscriber circuit S is connected to one input terminal of the OR gate 76.
Ant game in 2a included in the circuit of UB-n
Since the output of the door 5 is connected, the output is used for transmitting signals for selecting a central office line from the telephone 3b to the main unit 2a in the 5UB-1 and for the shift register 13.
5UB- by the same operation as explained in the memory of
An output is obtained at the output terminal of the gate door 5 included in the gate n, which is applied to one of the input terminals of the OR gate 76 and output to the output terminal thereof, so that the shift register 5
8 and 59 are rewritten by the operation described above.

The call is then stopped.

In addition, if the caller (receiver) stops the call before the called party answers, the flip-flop 85 is turned on by connecting the contact 87 of the telephone key of the circuit 3b of the telephone device-1. The AND gate 86 is opened by the output, and the timing pulse T'R is [AND gate 86 → OR gate 8
1→cable 88→flip-flop 70→AND gate 72] is applied to the reset terminal of the flip-flop 73, resetting it, and outputting the AND gate 7.
5's blockage is lifted.

As a result, as described above, when the recipient presses the office line key, the shift registers 58 and 59 are rewritten.

The call is then stopped.

When the ring key is pressed for the next call, the contact 84 becomes connected, and timing T'5 is applied to the reset terminal of the flip-flop 85 via the contact 84, resetting it.

The operations such as writing and rewriting of the shift registers 58 and 59 have been explained above, but the shift registers 58 and 59 will be described below.
Operations such as calling and displaying by tone will be explained using the output signal of 59.

First, calling by tone will be explained.

In Figure 2, 62, 63, 64, 65, 66.68°69
．． 77, 78, 79, 80, 89, and 90 are related circuits.

Shift registers 58, 59 stored as described above
The content of is output to its output terminal, and it is sent to decoder 6.
2, and manually connects the set terminal of the flip-flop 63 to set it.

Here, the output signal of the multi-by break 68 is manually input to the reset terminal of the flip-flop 3, and the flip-flop 63 is set to have reset priority characteristics, so that the output terminal receives an output signal synchronized with the multi-by break 68. is obtained, and the signal is sent to analog gate 6
The output signal of the sine wave oscillator 69 is input manually to the gate terminal of 5, which opens and closes it and sends the output signal of the sine wave oscillator 69.
8→amplifier 79→speaker 80], the signal is applied to the speaker 80 and makes it sound.

The above operations enable tone calling of individual telephones.

Although the case where the contact 82 is in contact has been described here, when the other contacts, for example 83, are in contact, the analog gate 66, for example, opens and closes in the same manner as described above, and the corresponding telephone speaker sounds. be.

Next, although individual calls are possible using the operation explained above,
At this time, it is necessary to select which central office line to receive the call.

In this case, the circuit shown in FIG. 3 is used.

Here, 95 is a decoder, 96, 97 are D-type flip-flops, 98, 99, 101, 102 are AND gates,
100 is an or gate, and 104 is a multi-buy break.

As for its operation, the shift registers 5B and 59 in FIG.
The output signal of
2→OR gate 100] to the gate (clock) terminal of the flip-flop 96,
An output signal synchronized with timing pulse T1 is output from flip-flop 96 and is applied to one of the input terminals of AND gate 99.

On the other hand, a specific cycle such as IH2 multi-by break 10
The output signal from 4 is applied to the other input terminal of AND gate 99, and the output signal of the product of the inclusion symbols is obtained at its output.

The signal obtained in this way is sent to the corresponding individual control line, for example, the control line of the meter, and
Manually complete the circuit shown in the figure.

In Figure 4, 106 and 107 are AND gates, 105 is a D-type flip-flop, and 108 and 109 are RS flip-flops.
The flop 110 is a display.

Here, the input signal is inputted to the set terminal of the flip-flop 105 of the circuit shown in FIG.

On the other hand, the output signal of the decoder 28 described above is
06 and obtains an output at its output terminal, which is applied to the set terminal of the flip-flop 108, setting it and outputting the display 110 at its output.
lights up.

The above makes it possible to display that a call has been received on an individual station line.

Next, station line acquisition in the present invention will be explained with reference to FIG.

The difference between Fig. 2 and Fig. 6 is that Fig. 6 is the circuit 1a of Fig. 2.
51 to 69, the OR gate 76, the AND gate 75 in the circuit 2a, and the circuit 1b are omitted, and the circuit 100a and the circuit 2 are omitted.
119°152, '153, 155 in a, and 129°130 part added to the telephone.

In FIG. 6, 100a is a station line circuit, 152. '1
53゜'157, 158, 159 is an and gate, 15
5゜162 is the OR gate, 156 is the inverter, 160
゜161 is a flip-flop, 119 and 125 are transformers, and 119-2 and 119-3 are two transformers of 119.
The next winding, 29 is a telephone communication circuit, 130 is a hook switch for common control with 36, 163 is a transistor, 164 is a relay, and 164-1 is its contact point.

In order to acquire the central office line, the manual input of central office line acquisition information from the telephone to the shift register 13 is the same as in the previous case.

Next, the output of the AND gate 153 obtained as above is passed through the OR gate 155 to the AND gate 158 for tl.
Only the output at the timing of is passed through, and the flip-flop 160 is set.

Further, when the power of the inverter 156 is at a low level (that is, there is no signal power) at the timing t1, the flip-flop 160 is reset.

Therefore, the flip-flop 160 continues to be set only as long as the telephone key 33 is kept pressed, pulses T2 are repeatedly sent from the telephone at the period of the counter 27, and the output of the shift register 13 is present. will be reset when it is cut off.

By setting the flip-flop 160, its output terminal goes high, turning on the emitter-collector of the transistor 163 through the OR gate 1(l)2, operating the relay 164, and connecting its contact 164-1.

As described above, a DC loop is formed for the station line, and the station line is captured.

Although Fig. 6 shows a case where there is only one telephone with a single central office line, a circuit of 100a is connected in parallel to point A in the figure,
N57, 158 human power signals t1 respectively tl5 t3
By changing to j tz t7°t9, etc., multiple office lines can be selectively captured from the telephone.

If a large number of telephones are used, this can be done by connecting the circuit 2a in parallel to point A in the figure.

The operation of acquiring the central office line has been described above, and next, the operation of operating the holding telephone key on the calling device in this state to place the central office line on hold will be described.

The hold information from the calling device is sent in the same way as the central line acquisition information.

When the telephone key for calling is pressed in the above-mentioned state where the central office line is captured, the contacts 82 and 84 are connected, and the signal T'5 from the decoder 28 is output.
is applied to flip-flop 70 through contact 84 in a similar manner to that described above.

As a result, the result is output to the delay circuit 74 as described above, and the output of the output and the output of the shift register 13 is the logical product of the station line acquisition information at the timing of t2 and 1 at the timing of the counter 1, that is, the output of the AND gate 152. It is applied to the AND gate 159 through the OR gate 155 and point A (transmission path).

On the other hand, with the arrival of the suspension information, the output of the AND gate 153, which has been output so far, is blocked by the inverter 156.

Therefore, the flip-flop 160 is reset, and the reset terminal R of the flip-flop 161 becomes a low level.

Also, the output terminal 0 of the flip-flop 160 becomes high level, and this, the signal from the point A, and the timing t2
As a result, the AND gate 159 is output, the flip-flop 161 is set, and its output Q is OR-[
Through 62, transistors 1 and 63 are turned on, driving relay 164, and connecting its contact 1641 to hold the central line.

Here, the telephone keys 33 and 34 are commonly used interlocking telephone keys, that is, telephone keys that are locked by pressing the office line telephone key.

That is, by the above operation, the central office line is put on hold with the central office line key remaining in the locked state.

Next, when re-answering the central office line, press the re-answer key provided on the telephone, the contact 87 will be connected, and a high level will be manually input to the set terminal of flip-flop 85 to set it. The output is applied to one of the input terminals of AND gate 86.

Therefore, the output T'R of the decoder 28 is [decoder 2
8 → AND gate 86 → OR gate 81 → Cable 88
→Flip-flop 70] route, manually connect the set terminal of flip-flop 70 and set it.

Here, the flip-flop is the flip-flop 4
It has the same function as 0.

Therefore, the timing pulse TR is output to the output terminal of the flip-flop 70 at the same timing as the timing pulse TR, which is applied to the reset terminal of the flip-flop 73 through the AND gate 2 to reset it.

As a result, the output of the delay circuit 74 disappears, and the output of the delay circuit 74 disappears.
-152 is closed and AND gate 153 is opened, so that the hold is released and the central line is re-acquired in the same way as when the central office line was captured.

Here, flip-flop 85 presses the ringing key and contacts 8
4 is connected, a reset terminal timing pulse T'5 of flip-flop 85 is applied through contact 84 to reset it.

Further, the contact 87 is constructed to operate when the central office line key is pressed, etc. 1. When the central office line key is pressed, the contact 87 becomes connected and the flip-flop 73 is reset by the above-described operation.

However, at this time, if the information for acquiring the station line, for example, the contact 33 is first connected and then the contact 34 changes, the information for acquiring the station line by the contact 33 will be cut off when it becomes disconnected. , the suspended state is maintained without reacquiring the central office line.

Next, if the contact point 33 is brought into contact, the object can be captured again.

When the central office line is put on hold, the present invention provides the following as a central office line holding signal:
Sends a central office line hold signal from the telephone and one piece of hold information common to each office line from the calling device, receives it in a time-division manner in a register in the main device, and then converts it into hold information for each office line. The system is configured to time-divisionally transmit the information through a transmission path to the office line circuit, selectively receive it at the office line circuit, and hold any office line on hold.

That is, in order to achieve this object, the present invention selectively connects a plurality of key telephones to a plurality of office lines using a main device, a plurality of call lines and a plurality of control lines, and furthermore, In a button telephone device in which a telephone is provided with a calling device, the main device includes a clock pulse, a plurality of rows of modulation/demodulation high-speed time slot pulses corresponding to the central office line, and a plurality of rows of low-speed time slot pulses for control signal transmission corresponding to the control line. and a first pulse generator 1, 2, 4 which generates a high-speed time slot pulse for reservation and a low-speed time slot pulse for reservation.
．． 5, a plurality of memos 1J12, 13, and 14 such as circulating memories corresponding to the button telephones, and a central office line control output transmitted from the corresponding button telephones via the control line to the plurality of lines of control signal transmission. a plurality of first memory cells for writing into a corresponding one of the plurality of memories in synchronization with an AND output of a corresponding one of the plurality of modulation/demodulation high speed time slot pulses and a corresponding one of the plurality of rows of modulation/demodulation high speed time slot pulses; a writing means 10, 11, 40, a plurality of first bistable circuits 160 corresponding to the plurality of office lines, respectively;
a plurality of second bistable circuits 161 provided corresponding to the plurality of first bistable circuits and reset by the output of the corresponding first bistable circuit; a plurality of station line closing means 162, 163, 164 for closing the corresponding station line when the corresponding one of the circuits is in a predetermined state; The plurality of first
a plurality of first gate means 156, 157 corresponding to the central office line for placing a corresponding one of the bistable circuits in the predetermined state;
, 158, receives a hold control output from the calling device in synchronization with the AND output of the low-speed time slot for control signal transmission and the high-speed time slot for hold, and in synchronization with the low-speed time slot for hold. a third bistable circuit 73 corresponding to the calling device to be set;
a delay circuit 74 for delaying the output signal of the bistable circuit by a certain amount; and a delay circuit 74 for delaying the output signal of the bistable circuit by a predetermined value; third gating means 152, 153 corresponding to the calling device for application to a corresponding one of the plurality of third gating means 152, 153; a plurality of second gate means 159 corresponding to central office lines, which take out the output of the telephone and use the output to put a corresponding one of the plurality of second bistable circuits into the predetermined state; to generate a synchronous time slot pulse substantially synchronized with a corresponding one of the plurality of rows of low-speed time slot pulses for control signal transmission and a pending synchronous time slot pulse substantially synchronized with the low-speed time slot for holding. second pulse generating means 26, 27, 28, operating means 33, 34 including a plurality of office line telephone keys corresponding to the office line and one holding telephone key, and a connection between the output of the operating means and the synchronized time slot pulse. a first control output means 31 and 32 for extracting the control output from the corresponding key telephone by AND output, and the control output is sent by a specified operation of the office line key in any one of the key telephones. One of the central office lines designated by the control output is connected to the key telephone in a time-divisional manner so that a central telephone call can be made, and the calling device is configured to correspond to each of the central telephones for individual calling. The second operating means 82 and 83 including an electric key provided in a second control output means 81 for extracting a control signal from the calling device, and one of the central office lines designated by the designated operation of the central office line key in any one of the plurality of button telephones is closed. is,
This is a central office line holding circuit for a button telephone device, characterized in that the closed central office line is put on hold by operating the holding telephone key.

As explained in detail above, the present invention is capable of automatically putting the central office line on hold when the calling telephone key is pressed, which eliminates the inconvenience of handling, and also achieves compact size, low cost, and improved quality. The practical effect is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a button telephone device of the present invention, FIGS. 2 and 7 are block diagrams showing examples of a call control circuit used in the present invention, and FIG. 3 is a block diagram of a call control circuit on the main device side regarding display in the present invention. FIG. 4 is a block diagram showing an example of a control circuit on the telephone side for display in the present invention. FIG. 5 is a time chart for explaining the present invention in detail. FIG. FIG. 2 is a block diagram showing a communication circuit system used in the invention.

Claims (1)

[Claims] 1 A plurality of key telephones are selectively connected to a plurality of office lines using a main device, a plurality of call lines, and a plurality of control lines, and at least one of the plurality of key telephones is equipped with a calling device. In the button telephone device, the main device includes a clock pulse, a plurality of rows of modulation/demodulation high-speed time slot pulses corresponding to the plurality of office lines, a plurality of rows of low-speed time slot pulses for control signal transmission corresponding to the plurality of control lines, and a hold. a first pulse generator for generating fast time slot pulses for use and slow time slot pulses for holding; a plurality of memories, such as a plurality of circulating memories, corresponding to the plurality of button telephones; The office line control output transmitted from the corresponding button telephone is ANDed with a corresponding one of the plurality of rows of low-speed time slot pulses for control signal transmission and a corresponding one of the plurality of rows of modulation/demodulation high-speed time slot pulses. a plurality of first writing means for writing to a corresponding one of the plurality of memories in synchronization with the output; a plurality of first bistable circuits respectively corresponding to the plurality of station lines; A plurality of second bistable circuits are provided corresponding to the first bistable circuit and are reset by the output of the corresponding first bistable circuit.
a bistable circuit, and a plurality of station line closures corresponding to the station lines that close a corresponding one of the plurality of station lines when a corresponding one of the plurality of second bistable circuits is in a predetermined state. A means of tying;
Corresponding to the central office line, the corresponding one of the plurality of first bistable circuits is brought into the predetermined state by a read output of the contents of the memory obtained in a designated time slot of the modulation/demodulation high speed time slots. a plurality of first gate means, receiving a hold control output from the calling device in synchronization with an AND output of the low speed time slot for control signal transmission and the high speed time slot pulse for holding; at least one third bistable circuit corresponding to the paging device that is set in synchronization with a slot pulse; a delay circuit that delays the output signal of the third bistable circuit by a certain amount; and the delay circuit. third gate means corresponding to a calling device for applying a corresponding one of the contents of the plurality of memories to a corresponding one of the plurality of first gate means according to a state corresponding to an output of the third gate means; A specified pulse of the modulation/demodulation high-speed time slot pulse takes out the output from a corresponding one of the plurality of third gate means, and the output controls the corresponding one of the plurality of second bistable circuits. a plurality of second gate means corresponding to central office lines for bringing the telephone into a predetermined state; a second synchronous time slot pulse for generating a synchronous time slot pulse and a holding synchronous time slot pulse substantially synchronized with the holding low speed time slot;
a pulse generating means, an operation means including a plurality of office line telephone keys corresponding to the office line and one holding telephone key, and an AND output between the output of the operation means and the synchronization time slot pulse to generate the control output from the corresponding button telephone. and a first control output means for extracting the central office line, the first control output means for outputting one of the central office lines designated by the control output sent by the designated operation of the central office line telephone key in any one of the key telephones. a second operating means configured to be connected to the button telephones in a time-sharing manner so as to be able to make central line calls, and including a telephone key provided in the calling device corresponding to each of the button telephones for individual calling; a common contact that operates in conjunction with the operating means, and a second control output means for extracting a control signal from the calling device by AND outputting the common contact and the output of the second pulse generating means. and one of the designated central office lines is closed by a designated operation of the central office line key on any one of the plurality of button telephones, and the closed central office line is put on hold by the operation of the holding telephone key. 1. A central line hold system for a button telephone device, characterized in that the key telephone device is configured such that: