JPS58106939A - Call signal transmitting circuit - Google Patents

Abstract

PURPOSE:To stabilize a call signal, by detecting opening or closing of semiconductor switches and using an exclusive operating circuit to prevent the simultaneous operation in a circuit for transmission of the call signal to a subscriber's terminal of a telephone exchange. CONSTITUTION:Conduction or nonconduction of p-n-p-n transistors TRs 11a, 11b, 12a, and 12b constituting semiconductor switches is detected by a detecting circuit 13c, and the detection output is transmitted as one of control information to a controlling circuit 14, and an exclusive opeating circuit 13 for delay circuits 13a and 13b having delay times longer than the turn-off time of p-n-p-n TRs 11a, 11b, 12a, and 12b is used to prevent the simultaneous operation of two semiconductor switches 11 and 12. Consequently, a stable circuit is obtained where a call signal source 5 and the earth do not collide.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a subscriber circuit of a telephone exchange, and more particularly to a paging signal sending circuit for sending a paging signal to a subscriber terminal via a transmission line.

FIG. 1 is a circuit diagram showing an example of a conventional calling signal sending circuit. DC current is supplied to the subscriber terminal 1 from a current supply circuit 3 via a subscriber line 2. Signals such as voice information are sent to and received from the subscriber terminal 1 via the subscriber line 2 and the current supply circuit 3 with the main body of the passenger exchange machine (not shown).

On the other hand, in order to send a paging signal to the subscriber terminal 1 prior to transmitting and receiving the voice information signal, a paging signal source 5 is connected to one line 6 via a resistor R+switch 4 via a resistor R2. A power source 7 is connected to the other line 8. The switch 4 has transfer contacts operative to switch between the ringing signal source 5 and the ground air.

FIG. 2 is a waveform diagram showing the state of sending out a calling signal to the subscriber terminal 1, which consists of a period 9 in which earth air is sent out and a period 10 in which an alternating current signal, that is, a calling signal is sent out, which is a combination of rainy periods. Various call signals are realized by appropriately selecting .

In such a conventional paging signal sending circuit, when the switch 4 switches from the paging signal source 5 to the ground, the line 6 is connected to the paging signal source 5 and the ground via the resistor R1 for a certain period of time. A situation arises in which it is not possible. At that time, subscriber line 2
The voltage of the paging signal source 5 at the time when the switch 4 is opened remains in the portion that was electrically connected to the paging signal source 5 of the subscriber terminal 1 or the like until just before.

This residual voltage gradually starts discharging due to the leakage resistance of the subscriber line 2, etc., and therefore has a frequency component extremely close to direct current. For this reason, a ring trip circuit (not shown) connected to both ends of the resistor R, which is activated and stops the ringing signal when the voltage at both ends exceeds a certain value, may be activated by mistake. It had

In order to eliminate the situation in which the contacts of the switch 4 are not connected to either the calling signal source 5 or the earth, a switch having a current self-holding function may be used. but,
When a switch having such a current self-holding function is used to alternately open and close the switch to switch between two signals, a situation occurs in which both signals are simultaneously applied for a certain period of time.

That is, in the case of a calling signal circuit, the calling signal and the earth signal collide in a short-circuited form with low impedance, which causes the contacts of the switch to be destroyed.

In addition, in conventional circuits, an electromagnetic component with a mechanical contact was used as the switch 4 for sending out a call signal, which required a large amount of power during operation, making it difficult to integrate the switch 4 with other components. Met.

It is an object of the present invention to prevent the part that was electrically connected to the calling signal source until just before from being charged to a potential other than the earth's potential even when the calling signal is stopped, and to prevent the calling signal from being charged to a potential other than the earth's potential. It is an object of the present invention to provide a calling signal sending circuit which avoids collision between the calling signal and the earth signal and has a configuration suitable for integration.

In order to achieve the above object, the present invention uses a pair of semiconductor elements having a current self-holding function such as pnpn (pnpn) transistors connected in antiparallel as a switch, and detects the open/closed state of the pair of semiconductor switches to detect the open/close state of the pair of semiconductor switches. An exclusive operation circuit is provided to close a pair of semiconductor switches while one of the switches is in an open state.

Hereinafter, the present invention will be described in detail based on drawings of embodiments.

The same parts are indicated by the same reference numerals, and the explanation thereof will be omitted.

Reference numerals 11 and 12 indicate semiconductor switches each having a current self-holding function, which correspond to a pair of switches 4 shown in FIG. 1. In this embodiment, each of the semiconductor switches 11 and 12 is a pnpn transistor 11.
a * 1 l b and 12a.

12b are connected in antiparallel.・13 is an exclusive operation circuit, which includes a first gate drive circuit 13a that drives the semiconductor switch 1, a second dart drive circuit 13b that drives the semiconductor switch 12, and a detection circuit that detects the conduction state of the semiconductor switches 11 and 12. 13c. The exclusive operation circuit 13 includes a control circuit 14 for controlling it.
is connected.

FIG. 4 is a waveform diagram for explaining the operation of this embodiment.

The operation of this embodiment will be explained below based on FIGS. 3 and 4.

When sending a paging signal to the subscriber terminal 1, the control circuit 14
Then, control signals 'r, , 'r2 having timings as shown in FIG. 4(A) are applied to the exclusive operation circuit 13. When the control signal Tl is ON and the control signal T2 is OFF, the first gate drive circuit 13a operates, and the second dart drive circuit 1
3b does not work. Therefore, the semiconductor switch 11 is closed, the semiconductor switch 12 is opened, and the ringing signal is output from the ringing signal source 5.
The subscriber terminal 1 is called through the loop of resistor R1 → line 6 → subscriber line 2 → subscriber terminal 1 → subscriber line 2 → line 8 → resistor R2 → negative power supply 7 → earth air.

Next, during the paging signal suspension period, that is, the period when the transmission of signals from the paging signal source 5 is suspended and the earth signal is transmitted to the subscriber terminal 1, the control signal T1 is OFF, and the control signal T2 is turned off.
becomes ON. Therefore, the semiconductor switch 12 is closed,
Semiconductor switch 11 is opened. In this way, the semiconductor switch 11 becomes conductive when the control signal T1 is ON, and the semiconductor switch 12 becomes conductive when the control signal T2 is ON, and the calling signal as shown in FIG. 4(B) is transmitted to the subscriber terminal 1. A repeated signal of the earth signal is sent out. At this time, since the semiconductor switches 11 and 12 are composed of semiconductor elements having a current self-holding function such as pnpn transistors, the control signal Tl changes from ON to OFF as shown as 0 point in FIG. 4(B). Furthermore, even when the control signal T2 is switched from OFF to ON, the current flowing through the semiconductor switch 11 may not immediately become zero due to the current self-holding function.

In this case, the detection circuit 13c in the exclusive operation circuit 13 detects that the semiconductor switch 11 is still in the closed state, and as shown in FIG.
The semiconductor switch 12 is not driven until the current self-holding function of the semiconductor switch 12 is released and the semiconductor switch 12 is in an open state.

Therefore, there is no collision between the two signals, which conventionally occurs when two signals are sent out by repeating alternate closing and opening using a semiconductor element having a current self-holding function.

FIG. 5 is a circuit diagram showing the embodiment shown in FIG. 3 in more detail.

The operation of this circuit will be explained.

A control signal is sent from the control terminal 20 to the first gate drive circuit 13a through the first delay gate circuit 2 so that the first gate drive circuit 13a operates and the second gate drive circuit 13b does not operate.
Drives the gate drive circuit 13a, and connects the N gate of the pnpn trannostar Ila via the drive terminal 22 and diode 23 to the N gate of the lannostall (pnpn) via the diode 24, or via the drive terminal 25 and diode 26, pnpn transistor lla
pnpn through the P gate or diode 27)
When P dart of transistor Jlb is driven, the calling signal source 5 outputs a calling signal to the output terminal 28. In this way, when the pnpn transistor Ila or the pnpn transistor 11b is conductive, the pnpn transistor Ila or the pnpn transistor 11a is conductive.

Each dart 11b and the transistor connected to it constitute a current mirror circuit, so when the transistor 11g is conductive, the current is PNP.
) Collector diode 30 of transistor 29 → current addition circuit 31i, current addition circuit 31 → diode 32 →
NPN) flows with the collector of Lanzosta 33. Also'
1 pnpn) Even when transistor llb is conducting, the current is PNP) Ranjimeter 34 → diode 3
5 -> current addition circuit 31 or current addition circuit 31 -> diode 36 -> NPN The information becomes operation prohibition information for the second dart drive circuit 13b via the two-delay dart circuit 38. Next, a control signal is sent from the control terminal 20, and the first dirt drive circuit 13h does not operate, and the second dirt drive circuit 1
When the second dirt drive circuit 13b is driven through the second dart delay circuit 38 so that the second dart drive circuit 13b operates, the drive terminal 39
and pnp through the diode 40) pnp through the pr-t of the transistor 12b or the diode 41
The P gate of n transistor 12a is driven. In this way, pnpn) transistor 12b or pnpn
) When transistor 12th is conductive, pnpn )
Since each dart of the runnostars 12a and 12b and the transistor constitute a current iler circuit, when the runnostar 12b is conducting, the current flows from the first delay gate circuit 21 to the diode 42 to npn) Flows with the collector of Ranno Star 43. In addition, when the pnpn trannostar 12a is conductive, the current flows from the first delay gate circuit 21 to the diode 44 to the collector of the lannostar 45 (from the diode 44 to the NPN) and the operation inhibition input information of the first gate drive circuit 13a. Become.

Now, consider a case where the semiconductor switch 11 is to be changed from a conductive state to a non-conductive state, and the semiconductor switch 12 is to be changed from a non-conductive state to a conductive state. When the control signal as described above is applied to the control terminal 20, each current mirror of the semiconductor switch 11 via the current adding circuit 31 is sent to the second delay dart circuit 38 together with the control terminal information. A drive current is output to the second FF-) drive circuit 13b with a long delay time, and the semiconductor switch 12 is driven via the drive terminals 39 and 46. Also, consider the case where the semiconductor switch 11 is to be changed from a non-conducting state to a conducting state, and the semiconductor switch 12 is to be changed from a conducting state to a non-conducting state. Control terminal 2
When a control signal as described above is given to 0, each current mirror of the semiconductor switch 12 through the diode 42 or the diode 44 is caused by the first delay dart circuit 2, along with the control terminal information, so that the current is greater than the turn-off time of the transistor pnpn). With the delay time, the first dart drive circuit 13a
A drive current is output to the drive terminal 22 and the drive terminal 25 to drive the semiconductor switch 11 .

Furthermore, when the semiconductor switch 12 attempts to become non-conductive,
The output from the drive terminal 46 is connected to N via a diode 47.
PN) by driving the pace of transistor 48
) pnpn ) NP between the dart and cathode of the transistor 12b or via the diode 49
By driving the pace of N Darlington transistor 50, flanging the dart of transistor 12h and the cathode of diode 50, forcing pnpn
pn) The anode current is actively cut off by drawing current from the P gate of the transistor 12a.

In this way, according to this embodiment, there is a means for detecting conduction or non-conduction of the pnpn transistor constituting the semiconductor switch, and a means for transmitting the detection output as one of the control information to the control input section, and a means for detecting the conduction or non-conduction of the pnpn transistor constituting the semiconductor switch. By using a large delay circuit, two semiconductor switches 1
Since the exclusive operation circuit 13 is provided to prevent the simultaneous operations of 1.12 from occurring, there is an advantage that a stable calling signal sending circuit without collision between the calling signal source 5 and the earth can be obtained.

As described in detail above, according to the present invention, a semiconductor switch having a current self-holding function is used, and an exclusive operation circuit is provided to control the sent signals so that they do not collide with each other. A stable calling signal sending circuit can be realized without destroying the contacts, and since it is possible to prevent malfunctions due to residual charges in the circuit that would otherwise exist when using a mechanical switch with transfer contacts.

Furthermore, since all the switches are made of semiconductors, it has the advantage of being easy to integrate including peripheral circuits.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an example of a conventional paging signal sending circuit, Fig. 2 is a waveform diagram showing a state of sending a paging signal to a subscriber terminal, and Fig. 3 is a circuit diagram showing an example of a conventional paging signal sending circuit. 4(A) and (B) are waveform diagrams for explaining the operation of the embodiment shown in FIG. 3, and FIG. 5 is a detailed circuit diagram of the embodiment shown in FIG. 3. It is. DESCRIPTION OF SYMBOLS 1... Subscriber terminal, 2... Subscriber line, 5... Calling signal source, 11.12... Semiconductor switch, 13.
・・Exclusive operation circuit. Continued from page 1 Inventor: Shiro Enami, 216 Totsuka-cho, Totsuka-ku, Yokohama, Hitachi, Ltd., Totsuka Factory Inventor: Kenzo Haseyo, 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Fujitsu Ltd. Nippon Telegraph and Telephone Public Corporation ■Applicant: NEC Corporation, 5-33-1 Shiba, Minato-ku, Tokyo Applicant: Hitachi Ltd., 5-1 Marunouchi-chome, Chiyoda-ku, Tokyo ■Applicant: Fujitsu Kawasaki Corporation 1015 Kamiodanaka, Nakahara-ku, Ichi, Showa (Monday/Monday) Director General of the Patent Office 1. Indication of the case 1982 Patent Application No. 205076 2. Name calling signal transmission circuit of the invention 3. Relationship with the person making the amendment Patent issue Request Appointment Office (
Address: 105) 1-7-12 Toranomon, Minato-ku, Tokyo Name (029) Oki 11 HFI Engineering S Co., Ltd. Representative
Director and President Masao Miyake 4, Agent
(4 others) Residence: Oki Electric Industry Co., Ltd., No. 12, 1-7, Toranomon, Minato-ku, Tokyo 105, Subject of amendment: ``Claims'' column in the description, Ushikogumi, and drawings. Middle ``Figure 3.'' (2) Revise Figure 3 of the drawing as attached. 2. Claims: In a calling signal sending circuit that sends out a calling signal and a ground air signal to a subscriber terminal via a subscriber line, a calling signal source and a ground air signal are connected to the subscriber line so as to be openable and closable. A call L2 comprising a pair of semiconductor switches and an exclusive operation circuit that detects the open/close states of the pair of semiconductor switches and closes the other semiconductor switch during a period in which one of the semiconductor switches is in the open state. Telegraph transmission circuit. Ward "0"

Claims (1)

[Claims] In a paging signal sending circuit that sends a paging signal and a ground signal to a subscriber terminal via a subscriber line, a pair of current self-holding type circuits connect a paging signal source and a ground signal to the subscriber line in an openable/closable manner. A calling signal sending circuit comprising a semiconductor switch and an exclusive operation circuit that detects the open/closed state of the pair of semiconductor switches and closes the other semiconductor switch during a period when one of the semiconductor switches is in the open state. .