JPS6356046A - Automatic switching device for telephone set - Google Patents

Abstract

PURPOSE:To obtain an automatic switching device provided with an automatic transfer function and a privacy call function used in common by adopting a constitution in which a switching element is turned on when the output voltage of a bridge type rectifier circuit exceeds a setting value. CONSTITUTION:Telephone sets T1, T2 are expressed equivalently in series circuits each comprising a bell and a capacitor and give a low resistance when a handset is hooked off. With a call signal given, a current is conducted through a capacitor, a voltage exceeding the setting value of a threshold value setting means 4 is outputted from a rectifier circuit 1 and the switching element 3 of the telephone set hooking off the handset at first keeps its ON-state by a current conducted the low resistance. Since the line voltage of subscriber lines L1, L2 is lower than the threshold value because of the low resistance, the switching element of the other telephone set turned once off is not turned on to attain privacy call. When both the handsets of the telephone sets of the switching sender and destination are hooked off and the handset of the telephone set of the switching sender is hooked on, the switching element of the switching sender is turned off and that of the switching destination is turned on to apply the switching.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to an automatic switching device with a secret function suitable for use in community telephone equipment, and in particular, is designed to protect the memory contents of a telephone with a memory device. Regarding automatic conversion equipment.

[Prior Art] In a community telephone device in which a main telephone and an attached telephone are connected to one subscriber line, automatic switching can be performed by adding an automatic switching device. Each operation in this case is as follows.

■When making a call, lift the handset, check the dial tone, and dial as you would a normal standalone phone call. If you don't hear a dial tone, it means that another phone is in use, so hang up the handset and wait for the line to become free.

■In the case of an incoming call When there is an incoming call, the bells of all telephones will ring. When the handset of any of the telephones is lifted, the bells of each telephone will stop ringing, and only the telephone 1' port from which the handset was lifted will be connected and can be answered.

■In the case of conversion If you pick up the handset and want to switch to another phone, pick up the handset of the convertible optical phone and then lower the handset of the convertible optical phone, and the switch will be automatically switched.

If you want to convert to something else after being converted, you can repeat the conversion using the same operation.

It is also possible to provide a confidential communication function by connecting an in-home relay box if necessary.

[Problems to be Solved by the Invention] By the way, the above-mentioned conventional automatic conversion device had the following drawbacks.

■It consisted of a relay circuit, and the circuit configuration was complicated.

■There was no device that had both an automatic conversion function and a secret message function.

■Telephones with memory devices, which are becoming popular throughout the year, usually obtain power for this memory device from the subscriber line, but with conventional automatic switching devices, when on-hook, that is, when the handset is turned off, In the lowered state, one side of the λ and the 7U phone were separated and became shaped like an f.
Power could not be supplied to the memory device.

This invention was made against this background, and therefore, it is possible to achieve the automatic conversion function and the confidential communication function using a simple circuit configuration.
An object of the present invention is to provide an automatic switching device for a telephone that is equipped with the following functions and is capable of supplying power to a memory device attached to the telephone.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a common telephone set in which a main telephone set with a memory device and an attached telephone set are connected in parallel to the same subscriber line. An automatic telephone switching device used by being connected to a telephone set includes a bridge-type rectifier circuit whose input end is inserted into the subscriber line, and a switching element which is connected to the output end of the rectifier circuit and is of an on-holding type. and a threshold setting means that is inserted between the output terminal of the rectifier circuit and the control terminal of the switching element and turns on the switching element when the output voltage of the rectifier circuit exceeds a set value; A high resistance connected to the input terminal, output terminal, or both of the rectifier circuit (4
ii.

[Function] Equivalently, when the handset is down, the telephone becomes a series circuit of a bell and a capacitor, and when the handset is raised, the resistance becomes low. Therefore, when the handset is hung up, the ringing signal (16
Unless the tlz AC interruption signal) does not come, the rectifier circuit?
The IX current does not flow, and the switching element remains in an OFF state. This keeps the telephone set disconnected from the subscriber line. However, since a minute current flows through the high resistance, the current is supplied to the memory device attached to the phone, and its contents will not be destroyed.

When a call signal is received, a current flows through the two-legged capacitor, a voltage exceeding the set value (threshold value) of the threshold value setting means is outputted from the rectifier circuit, and the switching element connected to the three telephones is turned on. Then, the switching element of ``1'' B, which is the first to pick up the handset, maintains the on state by the current flowing through the low resistance.Also, since the ringing signal stops at this time, the switching element of the other telephone The elements are turned off all at once.Furthermore, due to the low resistance mentioned above, the line voltage between the subscriber lines Ll and L2 becomes lower than the threshold value, so even if the handset is subsequently lifted up, the handset will be turned off once). The switching elements of the other telephones are not turned on, so that a private conversation takes place.

In addition, when the handset and receiver of the convertible optical telephone and the convertible optical telephone are both lifted up, when the handset of the convertible optical telephone is lowered, the switching element of the convertible optical telephone is turned off, the switching element of the convertible optical telephone is turned on, and the switching element of the convertible optical telephone is turned off. will be carried out. Note that details of these operations will be described later.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention. In the figure, T 1 and T 2 are the telephone main bodies. This telephone body Tl, T2 is an automatic conversion device TA
, TB are connected to the sound addition lines Lt and L2 via the rectifier circuit 1.

The rectifier circuit l has a bridge configuration, and its input terminal is
It is inserted in series on the subscriber line L2 side of the telephones TI and T2 which are connected in parallel. On the other hand, the positive output terminal 1a of the rectifier circuit l is
It is connected to the anode A of the thyristor 3 via the indicator 2, and the negative output terminal tb is connected to the cathode K of the thyristor 3. The display device 2 includes a series circuit of a resistor 2a and a light emitting diode 2b, and a 2.4V voltage connected in parallel to this series circuit.
A constant voltage diode 2c, and a thyristor 3
The light emitting diode 2b emits light when is on.

Gate G of the above thyristor 3 and positive output terminal 1 of the rectifier circuit l
A series circuit consisting of a 20 to 24 V constant voltage diode 1 and a resistor tA, 5 is inserted between the rectifying circuit 1 and the rectifying circuit 1. , the thyristor 3 is turned on. In other words, the constant voltage diode 4 functions as a threshold value setting means. Meanwhile, a resistor 6 and a capacitor 7 are connected in parallel between the gate G and the cathode of the Cyrisk 3.
Try to absorb pulse noise.

A high (Y) hole 8 is connected to the input terminal of the rectifier circuit 1. This is used to constantly flow a current to the memory device 15, which will be explained below, and has a value of approximately IOMΩ.

FIG. 2 is a block diagram of the telephones T I and T 2. The telephones T I and T 2 are composed of a dial circuit 11 , a communication circuit 12 , a transmitter 13 , and a receiver 14 .

Further, the subscriber lines L 1 and L 2 include a dial circuit 1
1, a memory device 15 is connected to the subscriber line ■,
Power is supplied from L and L2. This memory device 15 has a speed dial function and a repeat function (direct i
This function is used for functions such as calling the other party who called 'ifj again.

Next, the operation of this embodiment will be explained with reference to FIG.

First, the relationship between the operating mode and internal state of the telephone will be explained.

(B) On-hook (after time L1 in Figure 3) On-hook
When hooked up (with the handset hanging down), the telephone exchange sends 0■ to subscriber line I71 and subscriber line L2.
-48V is applied to each. Further, the telephone main bodies TI and T2 have a configuration in which a capacitor and a bell are connected in series.

Therefore, the TL current does not flow through the telephone main body T I and T 2, and the output voltage of the rectifier circuit I becomes 0.
maintains the off state. In other words, the telephone Tl.

T2 is disconnected from the subscriber line.

However, a small current flows through the high resistance 8 and is supplied to the memory device 15. As a result, the stored contents of the memory device are protected.

(b) Off-hook (time 2 to t3 in Figure 3(b))
, and after time t3 in FIG. 3(c)) When the handset is off-hook (the handset is hung up), the telephones T 1 and T 2 become equivalent to a resistance of about 150 ohms. If the bell goes off-hook when it is not ringing, thyristor 3 is in the off state, so rectifier circuit 1
-4.8V is applied to the input terminal of the rectifier circuit 1, and a voltage slightly lower than 48V is output from the output terminal of the rectifier circuit 1. This output cuff tHfE is supplied to the anode A of the thyristor 3 via the indicator 2, and is also applied to the gate G of the thyristor 3 via the constant 7u pressure diode 1 to turn on the thyristor 3. When the Cyrisk 3 turns on, the output voltage of the rectifier circuit l is equal to the voltage across the display 2 and the Cyrisk 3.
The sum of the forward voltages is approximately 3■. Also, at this time, subscriber line L1. The line voltage of L2 is below the threshold (1
Therefore, if the other telephones are subsequently taken off-hook, the thyristor 3 of this telephone will not turn on, and the telephone will not be connected to the line.

(c) When the bell rings (times tl to 2 in FIG. 3), in this case, the ringing signal (alternating current of fGtlz) sent from the switchboard flows through the capacitor inserted in the bell 11. Therefore, A full-wave rectified voltage is output from the rectifier circuit l.

Since this output has a voltage reaching a peak value of 100 cm, it exceeds the threshold of the constant voltage diode 4 and is applied to the gate G of the thyristor 3, turning on the thyristors 3 of all the telephones at once.

In this state, when a certain telephone is taken off-hook, the ringing signal stops, the bell stops ringing, and the thyristors 3 of the other telephones are turned off all at once. However, since the off-hook telephone is equivalent to a low resistance of about 150 ohms, a direct current circuit is formed and the thyristor 3 is maintained in the on state. At this time, the line voltage of the subscriber lines L I and L 2 rises above the threshold and becomes low, so even if the telephone goes off-hook thereafter, the thyristors 3 of other telephones will not turn on.

Next, each operation of calling, receiving, and switching will be explained.

(2) When making a call When the handset is lifted, the thyristor 3 is turned on as explained in (b) above. As a result, the telephone TI (or T2), which picked up the handset, connects the subscriber lines L 1 , L
2 is connected and a dial tone is heard. Check the dial tone and dial as you would a normal standalone phone. In this case, lift the handset of the other telephone and set the thyristor 3 of this telephone.
Since it is not turned on, it is not connected to the subscriber's line and there is no dial tone. In other words, if you don't hear a dial tone, it means that another phone is in use.
Hang up the handset and wait for the line to become free.

■In the case of an incoming call When there is an incoming call, the bells of all telephones TI and T2 will ring.
The thyristor 3 is turned on as explained in (c) above (see the output waveform of the rectifier circuit l in FIGS. 3(b) and 3(c)). Here, when the handset of the telephone Ti is turned off (time t2 in FIG. 3(b)), this telephone Ti is 15
Equivalent to 0 ohm. This causes the exchange to stop the ringing signal and to subscriber line Ll.

A direct current of approximately IOV is generated in L2. As a result, the bells of telephones TI and T2 stop ringing. In addition, the thyristor 3 of the telephone TI remains on, but in the telephone T2 with the handset still hung up, the bell and the capacitor are inserted in series, so the output of the rectifier circuit 1 disappears.
Thyristor 3 turns off.

Further, even if the handset of the telephone T2 is lifted up while the telephone T1 is busy, the thyristor 3 of the telephone T2 will not turn on because the line voltage between the subscriber lines L 1 and L 2 is lower than the threshold value. Therefore, the handset of telephone 'r2 is not connected to subscriber lines L1 and L2, and no voice can be heard. In other words, it has a secret function. In this case, a minute current flows through the high resistance 8, but this current is negligible and does not affect the confidential communication function to the same extent.

■In case of conversion, pick up the handset of telephone TI, then switch to another telephone T.
If you want to convert to 2, lift the handset of the convertible optical telephone T2 and then lower the handset of the convertible optical telephone Tl.
Automatically switched.

In other words, as shown at time t3 in FIG.
When the handset of the telephone TI is put down after picking up the handset of the telephone TI, the SIRISK 3 of the telephone TI is turned off because a direct current circuit is not formed in the telephone Tl. At this time,
Since Cyrisk 3 of telephone T2 is also in the off state, subscriber lines Ll and L2 are in the open state, and the voltage between them is 4.
8V (small pulse at time t3 in FIG. 3(a)). As a result, the output voltage of the rectifier circuit 1 gradually rises, and when it exceeds the threshold of the voltage regulator diode 4, the thyristor 3 of the telephone T2 is turned on, making it possible to respond. In addition, if you want to convert to something else after being converted, you can repeat the conversion by performing the same operation.

In the above embodiment, the indicator 2 is inserted in series with the thyristor 3, but even if the indicator 2 is removed, the same effect can be obtained.

In addition, switching elements are not limited to Cyrisk.
Any switching element that maintains an on state can be used in the same way.

Furthermore, although the high resistance 8 is connected to the input end of the rectifier circuit 1, the high resistance 8 may be connected to the output end of the rectifier circuit 1, as shown by the broken line in FIG. Further, one high resistor 8 may be connected to both the input end and the output end of the rectifier circuit l.

[Effects of the Invention] As explained above, the present invention can be used by being connected to each telephone of a communal telephone in which the main telephone equipped with a memory device and an attached telephone are connected in parallel to the same subscriber line. An automatic telephone switching device comprising: a bridge-type rectifier circuit whose input end is inserted into the subscriber line; an on-hold type switching element connected to an output end of the rectifier circuit; and an output end of the rectifier circuit. and a control terminal of the switching element, the threshold setting means is inserted between the input terminal and the output terminal of the rectifier circuit, and turns on the switching element when the output voltage of the rectifier circuit exceeds a set value. with a high resistance connected to the end, or both ends,
The following effects can be achieved.

■It can serve as a secret function and a conversion function at the same time.

■The circuit configuration is simpler than that of conventional conversion devices that use relay circuits, and reliability can be improved.

■It is possible to achieve lower prices.

-Even when the handset is hung up, current is supplied from the subscriber line to the memory device via a high resistance, so the contents stored in the memory device can be protected from destruction.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the configuration of an automatic conversion device according to an embodiment of the present invention, FIG. 2 is a block diagram showing the connection state between a telephone and a memory device, and FIG. FIG. 3 is a waveform diagram for explanation, and FIG. The waveform diagram of the line voltage of L2, (b) is the rectifier circuit of the converter TA! FIG. 3(c) is a waveform diagram of the output waveform of the rectifier circuit l of the converter TB. 1... Rectifier circuit, 3... Thyristor (switching element), 4...
... Constant voltage diode (threshold value setting means), 8...
...High resistance, 15...Memory device, T A, T B...Automatic conversion device Ll, L2
...Subscriber lines TI, T2...Telephone applicant Soft & Hard Co., Ltd. Figure 1" Figure 8

Claims (1)

[Claims] In an automatic telephone switching device used by being connected to each telephone of a communal telephone, in which a main telephone equipped with a memory device and an attached telephone are connected in parallel to the same subscriber line,
a bridge-type rectifier circuit whose input end is inserted into the subscriber line; an on-hold type switching element connected to the output end of the rectifier circuit; an output end of the rectifier circuit and a control end of the switching element; a threshold setting means inserted between the rectifying circuit and turning on the switching element when the output voltage of the rectifying circuit exceeds a set value; and a threshold setting means connected to the input terminal, the output terminal, or both of the rectifying circuit. An automatic switching device for a telephone, characterized in that it is equipped with a high resistance and a high resistance.