JPH0619241Y2 - Terminal equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a terminal device capable of multiplex transmission of a baseband signal with a small number of lines.

(Prior Art and its Problems) FIG. 1 shows an example of a conventional circuit of this type, in which a plurality of units are connected in parallel to a master station by two pairs and one common line. If the handset is picked up by the terminal device when the broadcast switch CK is not operated, the hook switches HS ₁ and HS ₂ operate, and [→
Transformer ₀₁ → A, A ₁ → transformer T ₁₁ → HS ₁ → transmitter amplifier TA → GA →] The transmitter amplifier TA is activated in the DC loop, and the transmitter signal from the transmitter is [TA → CK _{1, 2}
→ guide wire ring IND → HS _2, C ₁₁ ], and is output to the B line (terminal B-B ₁ ) and operates so that mutual communication can be performed with the other party connected in parallel. The line A is used as a broadcast channel, and when the terminal switch operates the broadcast switch CK to transmit from the transmitter, the transmission signal is [TA → C
K _1,2 → T ₁₁ ], then the A-line (terminal A-A ₁ ) enters the master station and T ₀₁ enters the amplifier PA. At the same time, the loop detector DET of the master station operates in the DC loop of the B line due to the operation of the switch CK ₃ , the amplifier PA is activated via the power supply circuit (not shown), and the transmission signal is the speaker SP.
Will be output. In this case, broadcasting and calling are independent. The advantage of this system is that a large number of terminal devices can be connected in parallel as shown in the figure, but there is a drawback in that a plurality of independent telephone calls cannot be made simultaneously because there is only one telephone line. In addition, there is an example in which a plurality of independent communication channels are realized by this method in the related art, which is the above-mentioned B.
It's an easy way to have multiple lines, and if you are new,
In reality, it is difficult to add a cable to an operating facility in terms of cost.

(Object of the Invention) The present invention provides a terminal device that can secure a transmission channel of three channels for a call for a call when one line for broadcasting and one line for a call are switched and used.

In order to achieve this object, the terminal device of the present invention comprises a broadcasting line for receiving a direct current from the master station and transmitting a low frequency signal between the master station and the master station. A hook line having a first hook contact and a second hook contact, which are arranged with a call line for transmitting a low-frequency signal and another grounded line and are turned on when off-hook, and are connected to the call line. A receiver circuit, a transmitter amplifier for amplifying the transmitter output, and first and second selection contacts for selecting the supply of the output of the transmitter amplifier to the broadcast line or the communication line and the communication line. A selection switch having a third selection contact provided in the handset circuit so as to form a direct current loop via the second hook contact, and first, second, and third channel selection contacts. A channel selection switch having First inserted into the transmitted low frequency signal of a broadcast channel and in the broadcast channel to prevent the direct transmission
In the direct current path formed from the midpoint of the primary winding of the transformer and the master side winding of the first transformer to the other line through the first hook contact and the power supply terminal of the transmitter amplifier. A parent station side via a first capacitor and the third channel selection contact between the inserted first coil and the midpoint of the primary winding of the first transformer and the other line. A second transformer to which a primary winding is connected, each terminal of the primary winding on the master station side transmitting a low frequency signal of the communication line and blocking a DC signal, has a second capacitor and a third capacitor. A third transformer connected to the master station side of the communication line via the second transformer, and the second channel selection contact between the middle point of the primary winding of the third transformer and the other line. A fourth transformer into which the primary winding on the master station side is inserted via the second transformer; 3 of the transformer and a fourth capacitor connected to said communication line so as to prevent DC current from flowing to the respective secondary windings of the transformer of the fourth, the second,
A third line and a fourth capacitor, and a second coil connected to the communication line so as to form a DC side path of the communication line to the third transformer, and further, the first channel selection The contact is formed on the secondary winding side of the second, third and fourth transformers by the communication line via the third transformer, or via the second transformer or the fourth transformer. The broadcasting line is secured by the broadcasting line and the low frequency signal is transmitted by the third transformer in the communication line, or It is configured to secure three communication channels which can be selected as to whether the low frequency signal is transmitted by the second transformer or the fourth transformer.

(Example) Hereinafter, an example of the present invention will be described in detail.

FIG. 2 shows an embodiment of the present invention.
Additional device A between the telephone TEL of the terminal device and the cable
With the addition of D, as a configuration, a plurality of terminal station devices TE _{1 to} TE _n are connected in parallel to the master station. For example, if the handset is picked up at the terminal device TE ₁ , the hook switches HS ₁ and HS ₂ operate and [→ OL ₁ → DT ₁
→ A, A ₁ → T ₁ → L ₁ → HS ₁ → TA → IGA → GA
The transmission amplifier TA is activated by the DC loop of [→] and the transmission signal from the transmitter is [TA → CK _1,2 → IND → HS
_2, C ₁₁ ], and is output to the terminals 1B and 1B ₁ . Here, the selection switch CH of the channel 1 of the additional device AD
_{When 1} is operated, the signals of 1B and 1B ₁ are [C ₄ →
CH ₁ → T ₃ → C ₂ , C ₃ ] through B line (terminal BB
₁ ) and connected in parallel to it, channel 1
It operates so that mutual communication can be performed with another terminal device that operated the selection switch CH ₁ . If the selection switch CH 2 of the channel ₂ is operated instead of the selection switch CH ₁ of the channel ₁ , the signals of 1B and 1B ₁ will be [C ₄ → C
H ₁ → T ₄ → CH ₂ → T ₃ → C ₂ , C ₃ ], B, B
_The signal is output between _1- GA and is connected in parallel to the _1- GA, and operates so that mutual communication can be performed with another terminal device that operates the channel 2 selection switch CH ₂ . Channel 1
If the selection switch CH 3 of the channel ₃ is operated instead of the selection switch CH ₁ of _{No. 1} , the signals of 1B and 1B ₁ are [C
₄ → CH ₁ → T ₂ → CH ₃ → C ₁ →→ T ₁ ], A,
It is output between A _{1 and} GA, connected in parallel to this, and CH
₃ operates so that mutual communication can be performed with another terminal device that operated ₃ .

The A line is used as a broadcast channel, and when the terminal device (for example, TE ₁ ) operates the switch CK to transmit from the transmitter, the transmission signal passes through [TA → CK _1,2 → T ₁₁ ] A Enter the master station via the line (terminal A-A ₁ ) and enter transformer D
The amplifier PA is entered via T ₁ . At the same time, the DC loop of the B line due to the operation of CK ₃ [→ R ₁ → OL ₂ → B ₁ → L
₂ → 1B ₁ → CK ₃ → IND → HS ₂ → 1B → L ₂ → B
→ OL ₂ →], the loop detector DET of the master station operates,
The amplifier PA is activated, and the transmission signal passes through the amplifier PA and is output from the speaker SP.

In this case, the broadcast and the three call channels are independent. FIG. 3 is a principle diagram showing this as a line configuration.

As described above, the switches CH ₁ to
By operating CH ₃ , without changing the line at all,
This is to upgrade the function of one call line to three call channels.

(Effect of the Invention) As described in detail above, according to the present invention, the call channel can be increased by two channels only by adding an additional device having a relatively simple structure in the line configuration using the two lines and the ground line. Since the DC loop can be a terminal device having a circuit configuration independent of the communication line, its economic effect is great.

[Brief description of drawings]

FIG. 1 is a connection diagram showing a connection relationship between a conventional terminal device and a master station, FIG. 2 is a connection diagram showing an embodiment of the present invention, and FIG. 3 is a diagram between the terminal devices of the present invention and a master station. It is a connection principle figure. TE ₁ , ..., TE _n ... terminal station, TEL ... telephone, AD ... additional device, T ... transmitter, R ... receiver, IND ... induction wire ring,
HS ₁ , HS ₂ ... Hook switch, TA ... Transmitting amplifier,
CK ₁ , CK ₂ , CK ₃ , ... Broadcast switch, T ₁₁ ,
T ₁ , T ₂ , T ₃ , DT ₁ ... Transformer, T ₁ , T ₂ , O
L ₁ , OL ₂ ... Obstructed wire ring, CH ₁ , CH _2, CH ₃ ... Channel selection switch, PS ... Battery, PA ... Power amplifier, SP ... Speaker, R ₁ ... Resistor, DET ... Loop detector, C ₁ , C ₂ , C ₃ , C ₄ , C ₁₁ ... Capacitor, DP
L ... Display circuit, LP ... Indicator light, 1A, 1A ₁ , A,
A ₁ , 1B, 1B ₁ , B, B ₁ ... Line terminal, 1GA, G
A ... Ground terminal.

Claims (1)

[Scope of utility model registration request] 1. A broadcasting line for receiving a direct current from the master station and transmitting a low frequency signal, a communication line for transmitting a low frequency signal, and another grounded line to the master station. And a hook switch having a first hook contact and a second hook contact that are turned on when off-hook, a receiver circuit connected to the communication line, and a transmitter amplifier for amplifying a transmitter output. , Forming a DC loop through the second hook contact with the first and second selection contacts for selecting to supply the output of the transmission amplifier to the broadcasting line or the communication line and the communication line A selection switch having a third selection contact provided in the handset circuit, a channel selection switch having first, second and third channel selection contacts, and transmitting a low frequency signal of the broadcast line. And prevent its direct current transmission. First inserted into the broadcast line to stop
In the direct current path formed from the midpoint of the primary winding of the transformer and the master side winding of the first transformer to the other line through the first hook contact and the power supply terminal of the transmitter amplifier. A parent station side via a first capacitor and the third channel selection contact between the inserted first coil and the midpoint of the primary winding of the first transformer and the other line. A second transformer to which a primary winding is connected, each terminal of the primary winding on the master station side transmitting a low frequency signal of the communication line and blocking a DC signal, has a second capacitor and a third capacitor. A third transformer connected to the master station side of the communication line via the second transformer, and the second channel selection contact between the middle point of the primary winding of the third transformer and the other line. A fourth transformer into which the primary winding on the master station side is inserted via the second transformer; 3 of the transformer and a fourth capacitor connected to said communication line so as to prevent DC current from flowing to the respective secondary windings of the transformer of the fourth, the second,
A third line and a fourth capacitor, and a second coil connected to the communication line so as to form a DC side path of the communication line to the third transformer, and further, the first channel selection The contact is formed on the secondary winding side of the second, third and fourth transformers by the communication line via the third transformer, or via the second transformer or the fourth transformer. The broadcasting line is secured by the broadcasting line and the low frequency signal is transmitted by the third transformer in the communication line, or A terminal device configured to achieve the securement of three communication channels that are selectable as to whether the low frequency signal is transmitted by the second transformer or the fourth transformer.