JP4045520B2 - Ringing signal application control circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a circuit for controlling a terminal device so as not to be applied by disconnecting the terminal device when an incoming bell signal is generated when a terminal device connected to a telephone line such as a personal computer is used.
[0002]
[Prior art]
In recent years, the number of devices connected to telephone lines has increased, and is disclosed in Utility Model Registration No. 2506967, Utility Model Registration No. 2506970, and Utility Model Registration No. 2538227 according to the applicant's invention. The number of telephone-related devices that store and use power from a telephone line, such as devices or circuits, is increasing. Such various terminal devices are always connected to a telephone line, which is a load on the telephone line.
[0003]
For terminal devices connected to telephone lines, including the above-mentioned terminal devices, the following conditions are stipulated as regulations or technical standards of communication carriers. That is, according to laws and regulations, the insulation resistance of the equipment connected to the analog telephone line is set to 1 MΩ or more, the capacitance when the incoming bell signal is generated is set to 3 μF or less, and as a technical standard, the incoming bell signal The DC resistance at the time of occurrence is determined to be 10 KΩ or more.
[0004]
[Problems to be solved by the invention]
However, to satisfy all the above conditions, it is necessary to comprehensively design all terminal devices connected to a telephone line such as a personal computer, or to reduce the originally required power storage capacity. There has been a problem that the design of various devices used in combination becomes complicated and the performance must be lowered.
[0005]
In particular, the ringing bell signal is an AC voltage signal obtained by superimposing a 75-volt AC voltage on a 48-volt DC voltage supplied during standby, and considering the increase in current when this ringing bell signal is generated, the capacitor However, it is necessary to keep the value of the charging current low when the telephone is on standby and during the incoming bell signal suspension period, and there is also a problem that it takes a long time for charging when the telephone is on standby.
[0006]
In addition, in the case of a device that does not need to use a plurality of terminal devices or input an incoming call bell signal, if these devices are always connected to a telephone line terminal, the load becomes large and it becomes difficult to satisfy the above conditions. There was also. For example, when three terminal devices are normally connected to a telephone line terminal, the capacity reaches 3 μF when a ringing bell signal is generated, and no further terminal devices can be connected. However, the terminal device may be used exclusively for transmission. In such a case, it is not necessary to input the incoming call bell signal, and if the incoming call bell signal is cut off, it can be added.
[0007]
The present invention has been made in view of the above-described problems of the prior art, and provides an incoming call bell signal application control circuit that disconnects an incoming call bell signal from being applied to a terminal device when the incoming call bell signal is generated.
[0008]
[Means for Solving the Problems]
The incoming bell signal application control circuit according to the present invention includes a terminal bridge connected to a telephone line terminal and a diode bridge connected to the telephone line terminal and outputting the incoming bell signal with the polarity of the alternating voltage superimposed on the direct current voltage. A first capacitor connected to the output terminal of the diode bridge to be charged, an electronic switching switch provided between the telephone line terminal and the terminal device, and an output terminal of the diode bridge A connection control circuit for controlling on / off of the connection electronic switch; an electronic switch connected in series to the connection control circuit; and an output terminal of the diode bridge connected to the incoming bell signal. When generated, the electronic switch is turned on, and a current is passed through the connection control circuit to turn off the connection electronic switch and turn on the terminal device. A switch control circuit for disconnecting from the line terminal; and when the electronic switch is in an on state, the switch is connected to the first capacitor via the electronic switch to be charged; and when the electronic switch is in an off state, the connection control circuit And a second capacitor through which a current flows. Further, in the incoming bell signal application control circuit, when the electronic switch is turned on between the first and second capacitors and the diode bridge, the first and second capacitors are turned off. Is provided from the diode bridge. Further, the switch control circuit in the incoming bell signal application control circuit is connected to the output terminal of the diode bridge, turns on the electronic switch after a predetermined time from the occurrence of the incoming bell signal, and supplies current to the connection control circuit. The terminal electronic device is disconnected from the telephone line terminal by turning off the electronic switch for connection.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
In the incoming bell signal application control circuit of the present invention, the switch control circuit turns on the electronic switch in response to the occurrence of the incoming bell signal. As a result, the connection control circuit is conducted through the electronic switch, and the connection electronic switch is turned off to disconnect the terminal device from the telephone line. As described above, when the terminal device is disconnected from the telephone line when the incoming call bell signal is generated, it is only necessary that the condition according to the law or the technical standard is satisfied without the terminal device.
[0010]
On the other hand, when the electronic switch is turned on, a current flows from the previously charged first capacitor to the second capacitor, and the second capacitor is charged. Then, the electronic switch is turned off during the period between the output waves of the half-wave rectified incoming bell signal or during the pause period of the incoming incoming bell signal intermittently. Supplied, the connection control circuit keeps the connection electronic switch in the OFF state. For this reason, the terminal device is disconnected from the telephone line as long as the incoming bell signal is generated.
[0011]
【Example】
FIG. 1 is a circuit diagram showing an incoming bell signal application control circuit according to an embodiment of the present invention.
[0012]
L1 and L2 are telephone line terminals of a telephone office line, and a DC voltage of about 48 volts is supplied during normal telephone standby, and an alternating voltage of 75 volts is superimposed on this DC voltage as an incoming bell signal.
[0013]
The diode bridge DB is connected to the telephone line terminals L1 and L2, and outputs a voltage signal having a certain polarity from its output side.
[0014]
The current limiting resistor R1 has one end connected to the output end of the diode bridge DB, and the other end connected to a connection control circuit and a first capacitor, which will be described later. The resistance value of the resistor R1 is set in consideration of the maximum current of the current value so that the charging current of the first capacitor, which will be described later, does not operate the telephone exchange.
[0015]
The first capacitor C1 has a relatively large capacity, is connected to the output terminal of the diode bridge DB via the resistor R1, and is charged when waiting for a call.
[0016]
The terminal device 2 and the connection electronic switch 4 are connected in series between the telephone line terminals L1 and L2. The terminal device 2 is a personal computer or an adapter device for connecting various devices to a telephone line, and the connection electronic switch 4 is usually composed of a photocoupler light-receiving element or a photomoss relay that is conductive in an on state. It is.
[0017]
The on / off control circuit 6 controls on / off of the on-off electronic switch 4, and emits light with the resistor R1 and the resistor R4 connected in series to the output terminal of the diode bridge DB via an electronic switch described later. It consists of element PC. In this embodiment, the light emitting element PC is coupled to a light receiving element as the connection electronic switch 4.
[0018]
The electronic switch Q1 is composed of a transistor, the collector of which is connected to the switching control circuit 6, and the emitter of which is connected to the output terminal of the diode bridge DB. Is supplied with current.
[0019]
The switch control circuit 8 includes a Zener diode ZD and resistors R2 and R3 connected in series between the telephone line terminals L1 and L2, and the base of the electronic switch Q1 is connected between the resistors R2 and R3. The threshold value of the Zener diode ZD is higher than the voltage of 48 volts when the telephone is on standby, and is set to a predetermined value in the incoming bell signal of 75 volts and 16 Hz superimposed thereon. Accordingly, the Zener diode ZD is energized when an incoming bell signal is generated, and the voltage is divided by the resistors R2 and R3 to turn on the electronic switch Q.
[0020]
The second capacitor C2 forms a closed loop with the switching control circuit 6 when the electronic switch Q1 is in an off state, and is connected to the first capacitor C1 when the electronic switch Q1 is in an on state. And the collector of the electronic switch Q1. The capacity of the second capacitor C2 is smaller than that of the first capacitor C1.
[0021]
In the incoming bell signal application control circuit configured as described above, when an incoming bell signal is generated, the Zener diode ZD is turned on by the voltage superimposed on the voltage during telephone standby, thereby turning on the electronic switch Q1. As a result, the light emitting element PC is connected to the output terminal of the diode bridge DB and the first capacitor C1 via the resistor R1 and the electronic switch Q1, and light is emitted by the current supplied at this time. When the light emitting element PC emits light, the light receiving element as the connection electronic switch 4 which is normally in the on state is turned off, and the terminal device 2 is disconnected from the telephone line terminals L1 and L2.
[0022]
On the other hand, when the electronic switch Q1 is turned on, the second capacitor C2 is connected to the first capacitor C1 via the electronic switch Q1, and is charged by the current from the first capacitor C1. Further, the electronic switch Q1 is in a state of repeatedly turning on and off by a voltage signal obtained by half-wave rectifying the incoming bell signal, which is an AC voltage signal of 16 Hz, and immediately before the electronic switch Q1 is in the off state. A current flows from the charged second capacitor C2 to the light emitting element PC, causing the light emitting element PC to emit light. For this reason, while the incoming bell signal is generated, the electronic switch Q1 is repeatedly turned on and off, but the light emitting element PC is kept in the light emitting state.
[0023]
When the incoming bell signal is generated as described above, the terminal device 2 is disconnected from the telephone line terminals L1 and L2 without a time lag, and no incoming bell signal is applied to the terminal device 2, and the incoming bell signal Since the terminal device 2 is disconnected from the telephone line terminals L1 and L2 when it occurs, the above-described conditions can be easily satisfied.
[0024]
Since the incoming bell signal application control circuit in this embodiment is connected to the telephone line terminals L1 and L2 when the incoming bell signal is generated, the DC resistance viewed from the telephone line when the incoming bell signal is generated, that is, the resistor R1, Zener It is necessary to select each value so that the combined resistance converted from the charging current of the diode ZD, the resistor R4, and the first and second capacitors C1 and C2 is 10 KΩ or more. In addition, the value of the resistor 1 is adjusted and the charging current is taken into consideration so that the capacity seen from the telephone line when the incoming bell signal of the first and second capacitors C1 and C2 is generated does not become excessive. .
[0025]
FIG. 2 is a circuit configuration diagram showing an embodiment in which a part of the incoming bell signal application circuit shown in FIG. 1 is changed. In this embodiment, a second electronic switch Q5 is provided between the resistor R1 and the first and second capacitors C1 and C2, and the first and second capacitors C1 and C2 are connected to the diode bridge when an incoming bell signal is generated. The first and second capacitors C1 and C2 are separated from the output terminal of DB so that they do not become a load when an incoming bell signal is generated.
[0026]
That is, the second electronic switch Q5 comprises a transistor, its collector is connected to the output terminal of the diode bridge DB via the resistor R1, and its emitter is connected to the resistor R4 and the first and second capacitors C1 and C2. The base is connected to the output terminal of the diode bridge DB via the resistor R5, and is connected to the connection point between the light emitting element PC and the second capacitor C2.
[0027]
The second electronic switch Q5 is in an on state because the electronic switch Q1 is in an off state during telephone standby, and supplies a charging current to the first capacitor C1. Then, when an incoming call bell signal is generated and the electronic switch Q1 is turned on as described above, the second electronic switch Q5 is turned off, and when the electronic switch Q1 is turned off, the second electronic switch Q5 is turned on. It becomes a state. Therefore, the second electronic switch Q5 is turned off only when the voltage is increased by the incoming bell signal, and the first and second capacitors C1 and C2 are disconnected from the output terminal of the diode bridge DB. As a result, the telephone line terminal The number of terminal devices connected to can be further increased. Other operations are the same as those in the above-described embodiment.
[0028]
FIG. 3 is a circuit configuration diagram showing an embodiment in which a part of the incoming bell signal application control circuit shown in FIG. 1 is further modified. In this embodiment, the switch control circuit 8 for controlling on / off of the electronic switch Q1 is changed so that the electronic switch Q1 is turned off after a predetermined time since the incoming bell signal is generated.
[0029]
That is, the switch control circuit 18 has a Zener diode ZD and resistors R2 and R3 connected in series between the outputs of the diode bridge DB, like the switch control circuit 8 described above, and the Zener diode ZD. And a resistor R2 is provided with a diode D for preventing backflow. The switch control circuit 18 is also provided with a third electronic switch Q2 made of a transistor, the collector of which is connected to the connection point between the Zener diode ZD and the diode D via the resistor R6, and the electronic switch Q1. And the emitter is connected to the output terminal of the diode bridge DB, the base is connected between the resistors R2 and R3, and is connected to the output terminal of the diode bridge DB via the third capacitor C3. Yes.
[0030]
In the switch control circuit 18, when an incoming bell signal is generated, the third electronic switch Q2 is turned on after a predetermined time by the time constants of the resistors R2 and R3 and the third capacitor C3. Then, when the third electronic switch Q2 is turned on, the base of the electronic switch Q1 is grounded and turned on, and the light emitting element PC emits light as described above. In this way, it takes a certain time from the occurrence of the incoming call bell signal until the electronic switch Q1 is turned on. During this time, several incoming call bell signals are applied to the terminal device.
[0031]
As described above, by stopping the application of the incoming bell signal to the terminal device after a predetermined time from the occurrence of the incoming bell signal, it is possible to detect the occurrence of the incoming bell signal on the terminal device side.
[0032]
As shown in FIG. 3, a terminal device 2 such as a telephone is connected to the telephone line terminals L1 and L2 via a diode bridge DB2, and a resistor R7 and a light receiving element such as a phototransistor are provided between the outputs of the diode bridge DB2. The electronic switch 4 for connection is connected, the bases of the electronic switches Q3 and Q4 made of Darlington-connected transistors are connected to the connection point between the resistor R7 and the electronic switch 4 for connection, and the collector is connected to the diode via the resistor R8. You may connect between the output of bridge DB2. By connecting in this way, when the light emitting element PC emits light, the disconnecting electronic switch 4 cuts the base voltage of the electronic switch Q4, the electronic switches Q3 and Q4 are turned off, and the terminal device 2 is disconnected.
[0033]
【The invention's effect】
According to the present invention, since various terminal devices can be disconnected from the telephone line when an incoming call bell signal is generated, for example, three terminal devices are connected within the limit capacity of 3 μF stipulated by laws and regulations. It becomes possible to add terminal devices, and more terminal devices can be connected and used.
[0034]
In particular, in terminal equipment that obtains power from the telephone line and stores it, the charging current of the capacitor can be set to the maximum value during telephone standby without considering the incoming bell signal, and the charging speed can be increased. Can do.
[Brief description of the drawings]
FIG. 1 is a circuit configuration diagram showing an incoming bell signal application control circuit according to an embodiment of the present invention.
FIG. 2 is a circuit configuration diagram showing an embodiment in which a part of the incoming bell signal application control circuit shown in FIG. 1 is changed.
FIG. 3 is a circuit configuration diagram showing an embodiment in which a part of the incoming bell signal application control circuit shown in FIG. 1 is further modified;
[Explanation of symbols]
2 Terminal equipment 4 Electronic switch for connection 6 Connection control circuit 8, 18 Switch control circuit DB, DB2 Diode bridge Q1 Electronic switch Q5 Second electronic switch C1 First capacitor C2 Second capacitor

Claims (3)

A terminal device connected to a telephone line terminal;
A diode bridge that is connected to the telephone line terminal and outputs the incoming bell signal with the same polarity of the alternating current voltage superimposed on the direct current voltage;
A first capacitor connected to the output of the diode bridge and charged;
An electronic switch for connection provided between the telephone line terminal and the terminal device;
A connection control circuit connected to the output terminal of the diode bridge and controlling on / off of the connection electronic switch;
An electronic switch connected in series to the disconnection control circuit;
The terminal device is connected to the output terminal of the diode bridge and the electronic switch is turned on by the generation of the ringing bell signal to pass the current to the connection control circuit to turn off the connection electronic switch. A switch control circuit for disconnecting from the telephone line terminal;
A second capacitor that is connected to and charged by the first capacitor through the electronic switch when the electronic switch is in an on state, and that causes a current to flow through the disconnection control circuit when the electronic switch is in an off state;
An incoming bell signal application control circuit comprising: Second electrons provided between the first and second capacitors and the diode bridge, which are turned off when the electronic switch is turned on to disconnect the first and second capacitors from the diode bridge. 2. The incoming bell signal application control circuit according to claim 1, further comprising a switch. The switch control circuit is connected to the output terminal of the diode bridge, and turns on the electronic switch after a certain time from the occurrence of the incoming bell signal and causes the current to flow through the connection control circuit, thereby supplying the connection electronic switch. 2. The incoming call signal application control circuit according to claim 1, wherein the terminal device is disconnected from the telephone line terminal by turning off the terminal device.

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