JPH0114758B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a button telephone device in which a plurality of key telephones are branch-connected to a main unit by at least one central office line communication line and at least one extension line communication line, In particular, it concerns extension calls.

In conventional branch-connected key telephone devices each having at least one circuit for a central office line and one extension line, extension calls include voice calls and tone calls using the extension lines. However, since the extension line cannot be used when making an extension call, the method used to call an extension is to transmit extension call information over a control line and operate the oscillator built into each telephone to make a tone call. Therefore, when making an extension call, only a tone call can be used to make an extension call, and each telephone must be provided with an oscillator for tone calls, which has the disadvantage of increasing costs and reducing functionality.

In order to solve these drawbacks, the present invention provides a key telephone device that is capable of realizing voice calls and tone calls for extension calls by using a central office line communication path during extension calls.

The present invention will be explained in detail below using the drawings.

FIG. 1 shows an embodiment of the present invention in the case of one central office line, in which 1 is a central office line input terminal, 2 is a main device, and 3 is representatively shown as one of a plurality of telephones. Telephone, 4 is a central office line communication line, 5 is a signal transmission line, 11
is a power supply circuit, 12 and 13 are blockage wires, 21 is a control circuit, 22 is a gate circuit, 23 and 53 are relays,
24, 55 are FSK modulation/demodulation circuits (MODEM), 2
5, 54 are high pass filters (HPF), 26, 3
2 is an oscillator, 27, 29, 33, 59, 60, 6
3, 67, 68, and 70 are switches; 28 and 30 are band pass filters (BPF); 31 is a station arrival detection circuit for detecting the arrival of a call on the station line; 34 is a hold circuit;
51 is a low pass filter (LPF), 52 is a power supply smoothing circuit (DC), 56 is a control circuit, 57 is a switch, 58 is a communication circuit, 61 and 69 are low pass filters (LPF), 62 is a telephone key (KEY), 64,
71 is a DC blocking capacitor, 65 is an amplifier, 66
is a speaker. The cutoff frequency of each filter is, for example, as shown in the figure.

The power inside the main device 2 is supplied by the power supply circuit 11, and the power for the telephone 3 is sent through the route of [power supply circuit 11 → blocking wire 12 → signal transmission line 5 → low-pass filter 51 → power supply smoothing circuit 52], Supplied to each circuit. The power-on information of the power supply circuit 11 and the output of the control circuit 21 are input to the gate circuit 22, and the output operates the relay 23, and the contact 23-
1 and 23-2 are in the dotted line state. Furthermore, on the telephone 3 side, when the power is turned on, the relay 53 operates, and its contact 53-1 becomes a dotted line state.

Next, the digital signal output from the control circuit 21 as control information from the main device 2 to the telephone 3 is modulated into an FS signal by the FSK modulation/demodulation circuit 24.
The frequency of this FS signal is approximately 40KHz. The FS output signal from the FSK modulation/demodulation circuit 24 is [high pass filter 25 → signal transmission line 5 → high pass filter 5
4] route to the FSK modulation/demodulation circuit 55,
It is demodulated into a digital signal and input to the control circuit 56. Further, control information is similarly transmitted from the telephone set 3 to the main device 2 through the reverse route to that described above.

Next, the operation of calling an extension will be explained. In the case of a voice call, the caller switches the power switch 57 from off to on and presses the extension call switch on the telephone key 62 to give the control circuit 56 information about the extension call, and this information is sent to the reverse route as the control information. is transmitted to the main device 2. At the same time, in order to transmit voice signals, the telephone 3 on the calling side
→Full switch contact 57-1 →Switch, 5
9→switch 60→low-pass filter 1] to the signal transmission path 5, and in the telephone 3 on the called side, a route is formed from [low-pass filter 61→switch 60→switch 63→DC blocking capacitor 64→
Amplifier 65] route is formed, and the audio signal is output from speaker 66. In addition, in the case of tone calling, control information is transmitted to the main device 2 in the same manner as the above operation, the oscillator 26 is operated, and the calling tone is transmitted from [switch 27 → band pass filter 28 → signal transmission line 5 → low pass filter 61]. →Switch 6
0→switch 63→DC blocking capacitor 64→amplifier 65], and is output from the speaker 66.

When transmitting an extension call signal, the switch 57 is switched from off to on, and the call circuit 58 is switched from [talk circuit 58 → switch contact 57-1 → switch 59 → switch 60 → low-pass filter] in the telephone 3 on the calling side. 61→Signal transmission line 5]
A route is formed, and in the telephone 3 on the called side, [low pass filter 61 → switch 60 → switch 59
→Full switch contact 57-1 →Talking circuit 5
8] route is formed to enable extension calls.

When making an extension call during an extension call, the extension call method described above cannot be used because the extension call path is in use, so the extension call during an extension call is made using the following route. In the case of a voice call, the voice signal is sent to the telephone 3 on the calling side [call circuit 58 → switch contact 57-2 → switch 67 → switch 68 → contact 53-1 dotted line side → low-pass filter 6
9] is sent from the transmission path forming means on the calling side to the central office line communication path 4, and in the telephone 3 on the called side, it is transmitted through [low-pass filter 69 → contact 53-1 dotted line side → switch 68 → switch 70 → DC blocking]. The signal is transmitted through the transmission path forming means on the called side via the route ``capacitor 71 → amplifier 65'', and is output from the speaker 66. In the case of a tone call, control information is transmitted to the main device 2 in the same way as for the extension call, and the oscillator 26 forming the extension ring tone sending means operates, and the ring tone is changed from [switch 29 → band pass filter 30 →Relay contacts 23-1, 23-
2 dotted line side → Office line communication path 4 → Low pass filter 69
→Relay contact 53-1 dotted line side→Switch 68→
The signal is transmitted through the route of switch 70→DC blocking capacitor 71→amplifier 65], and is output from the speaker 66.

Incoming calls from the central office line (hereinafter referred to as "station arriving") are detected by the central office arrival detection circuit 31, and the central office arrival information is sent to the control circuit 21.
to operate the oscillator 32, and the station ringing tone is as follows: [Switch 33 → Bandpass filter 30 → Relay contacts 23-1, 23-2 dotted line side → Office line communication path 4 → Low-pass filter 69 → Relay contact 53- It is transmitted through the route of 1 dotted line side → switch 68 → switch 70 → DC blocking capacitor 71 → amplifier 65],
It is output from the speaker 66. When the control circuit 21 receives information that the called party has switched the switch 57 from OFF to ON as the control information, it restores the relay contacts 23-1 and 23-2 to the solid line state and inputs the station line. Terminal 1 and office line communication line 4
Connect. Therefore, the office line communication signal is as follows: [Office line input terminal 1 → relay contacts 23-1, 23-2 solid line side → office line communication path 4 → low-pass filter 69 → relay contact 53-1 dotted line side → switch 68 → The signal is transmitted through the route of switch 67 → switch contact 57-2 → telephone call circuit 58], making it possible to make telephone calls over the central office line. Further, the holding circuit 34 performs holding.

In addition, the second example shows an example in which this embodiment is extended to multiple lines.
As shown in the figure. In this embodiment, since the extension call signal is transmitted as is, the extension call signal cannot be transmitted while a telephone call is being made over the central office line.
However, the need to make an extension call during an extension call arises when the call arrives at the office during an extension call, so by putting the office line on hold,
A, 4-B are contacts 23-1a, 23-1b, 23
-2a and 23-2b, so extension calls are possible.

Further, as a modification of these embodiments, there is an embodiment in which an extension call signal outside the voice band is superimposed on the voice frequency signals of the office line communication paths 4, 4-a, and 4-b, thereby realizing a telephone call over the office line. is shown in Figure 3.

This is the bandpass filter 3 in Figure 1.
0 is deleted, modulation circuit (MOD) 35, 76, bandpass filter 36, 72, switch 73, 7
4, 77 and a demodulation circuit (DET) 75 are added.

In the case of a voice call, the extension ringing signal during an extension call is transmitted to the telephone 3 on the calling side by [call circuit 58 → switch contact 57-2 → switch 77 → modulation circuit 76 → switch 73 → bandpass filter 7
2] route to the office line communication path 4, and in the telephone 3 on the called side, it is transmitted from the [bandpass filter 72
The signal is transmitted along the route of switch 73→switch 74→demodulation circuit 75→amplifier 65] and is output from speaker 66. Furthermore, when a central office line call is being made, the sound of the central office line call is cut off by the switch 68 in the telephone that is not conducting the central office line call. When making a tone call, the oscillator 26 is activated by control information from the calling party,
The oscillation signal is transmitted through the route of [switch 29 → modulation circuit 35 → bandpass filter 36 → central line communication path 4 → bandpass filter 72 → switch 73 → switch 74 → demodulation circuit 75 → amplifier 65] and is sent out from speaker 66. Ru. Other operations are the same as those shown in FIG. 1, so explanations will be omitted.

It is also possible to extend this embodiment to the case of multiple lines as shown in FIG.

Furthermore, the configuration of the control circuit 21 or 56 is as follows:
Although it can be easily realized using ordinary logic circuits,
It is also possible to realize this by adopting storage program control by a processor.

As explained above, the present invention has enhanced functions such as being able to make an extension call even when an extension call is in progress, and making it possible to make a tone call by simply having a tone circuit for extension calls in the main device, while reducing costs. There are advantages that can be achieved. It is particularly useful for application to branch-connected key telephone devices.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention in the case of one central office line, FIG. 2 is a circuit diagram showing part of an embodiment of the present invention in the case of multiple central office lines, and FIG. FIG. 2 is a circuit diagram showing an embodiment of the present invention in the case where an extension calling signal is modulated and transmitted.

Claims (1)

[Scope of Claims] 1. In a button telephone device in which a plurality of key telephones are branch-connected to a main device by at least one central office line communication path and at least one extension communication path, the main device has an extension call line. an extension ringing tone transmitting means for transmitting a sound; and an extension ringing tone transmitting means for transmitting sound from the extension ringing tone transmitting means when in a switching state in which the office line communication path is switched to be used as another extension communication path different from the extension communication path. at least each of the plurality of key telephones is provided with a switching means configured to send an extension ringing tone to the extension communication path, and at least each of the plurality of key telephones has a switching means configured to transmit an extension ring tone to the extension communication path when the switching means is in the switching state. A button telephone device characterized in that a transmission line forming means is provided for connecting a speaker circuit for listening to an extension ringing tone to the other extension line communication line formed separately via the office line communication line. 2. The button telephone device according to claim 1, wherein the transmission path forming means is configured to enable transmission of the extension ring tone only when the office line communication path is not in use. . 3. The button according to claim 1, wherein the transmission path forming means is configured to enable transmission of the extension ring tone by transmission outside the audio frequency band of the central office line communication path. Telephone device.