JPS62178097A - Key telephone system - Google Patents

Abstract

PURPOSE:To make a terminal telephone set small in size by providing a central office line interface part of a main device with a voice switch instead of a voice switch in each terminal telephone set. CONSTITUTION:In the case of loud talking between a terminal telephone set connected to an extension 25 and a telephone set connected to a central office line 31, a signal which operates a comparator 38 is sent through a control line 39. The comparator 38 compares the voice level of a reception line 40 and that of a transmission line 41 and sends signals to voice switches 36 and 37 so that the signal having the higher voice level passes through but that having the lower voice level is attenuated. Therefore, the occurrence of howling is prevented in case of loud talking to the telephone set connected to the central office line 31 even if a hybrid circuit 32 is mismatched. Thus, voice switches are provided in a central office line interface part 45 to make the terminal telephone set small in size by the space of voice switches.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a button telephone device that transmits voice signals between a terminal telephone and a main device and within the main device by a digital line, and has a loudspeaker function.

[Technical background of the invention] FIG. 3 shows the configuration of a general key telephone device.

The terminal telephones 11 to 1n are connected to the main device 3 via internal lines 21 to extensions 2n, and the office line 4 is connected to the terminal telephones 11 to 1n via the office line interface section 5 in the main device 3. Ru. For example, terminal phone 1n
is connected to the office line 4 via the extension line 11, the transmission line 6 in the main device 3, and the office line interface section 5 to the office line 4. In addition, in order to connect the terminal telephone 11 and the terminal telephone 1n, an extension 21 is required from the terminal telephone 11 to the terminal telephone 1n.
It is connected to the terminal telephone 1n via the transmission line 7 in the main device 3 and the extension 2n.

In recent years, button telephone devices have been considered that transmit voice using digital signals between a terminal telephone and a main device and within the main device. In other words, if you explain above the third section, extensions 21 to 2n,
Voice is transmitted as a digital signal on the transmission path 6 and the transmission path 7, and in the terminal telephones 11 to 1n, this digital signal is converted into an analog signal and transmitted to the operator as voice. Note that when the office line 4 is a line that transmits voice as an analog signal, the office line interface section 5 converts the analog signal into a digital signal and sends it to the transmission line 6. Further, the office line interface section 5 converts the digital signal sent from the transmission line 6 into an analog signal and sends it to the office line 4.

This type of key telephone device has three types of functions: loudspeaker voice calls between extension terminal phones, loudspeaker calls between extension terminal phones, and loudspeaker calls with central office line telephones (hereinafter simply referred to as the loudspeaker function). There are things that I have. In this type of button telephone device, the terminal telephone and central office line interface section were constructed as shown in FIGS. 4 and 5, respectively.

In FIG. 4, 11 is a speaker for loudspeaking, 12 is a microphone also for loudspeaking, 13 and 14 are amplifiers, 15 and 16 are audio switches, 17 is a converter,
18 is a controller for controlling the audio switch 15; 19
20 is a controller for controlling the audio switch 16, 20 is a controller for controlling the converter 17, 21 is a receiver, 22 is a transmitter, 23 is a codec, 24 is a digital interface, 25 is an extension line, and 26 is a This is a data line connected to a control unit of a terminal telephone (not shown). Note that in FIG. 4, the circuit configuration for making a handset call is omitted. The digital signal sent from the extension 25 is sent to the receiver 21 as an analog signal via the digital interface 24 and the codec 23, and then the audio switch 15 and the amplifier 1.
The signal is output as audio from the speaker 11 via the speaker 3. Furthermore, the audio input from the microphone 12 is encoded as an analog signal by the codec 23 via the amplifier 14 and the audio switch 16, and is encoded by the codec 23 via the digital interface 24.
is sent to the extension line 25 as a digital signal. Here, when this terminal telephone 10 performs a loudspeaker call with a telephone connected to a central office line (not shown), a signal is sent from a control section (not shown) via the controller 20 to turn on the operation of the converter 17. The converter 17 compares the audio level of the transmitter 22 and receiving line 21 with the audio level of the transmitting line 22, and operates the audio switch 15 and the audio switch 16 to pass the higher audio level and attenuate the lower audio level. .

The office line interface section 30 shown in FIG. 5 converts the office line 31, which is a 2,000-wire system, into a 4-wire system using a hybrid circuit 32, and converts the analog signal sent from the office line 31 to a codec 33 and a digital signal. It is sent to the extension line 25 via the interface 34 as a digital signal. 35a and 35b
is a data line connected to a central control unit of the main unit (not shown).

Also, the digital signal sent from the extension 25 is converted into an analog signal via the digital interface 34 and codec 33, and further converted from a 2-wire system to a 4-wire system via the hybrid circuit 32, and then sent to the central office line 31. Send.

Since it is necessary to perform 2-wire to 4-wire conversion in the central office line interface section, a hybrid circuit 32 is provided as shown in FIG. 32, there is a risk that the voice on the receiving side may reach the transmitting side and cause howling. In order to prevent this howling, each terminal telephone is provided with an audio switch 15 and an audio switch 16, as shown in FIG.

[Problems with the Background Art] However, when each terminal telephone is provided with an audio switch in this way, there is a problem in that the miniaturization of the terminal telephone is hindered accordingly. Further, since a typical key telephone device has a large number of terminal telephones, there is a problem in that if as many voice switches as there are terminal telephones are required, the cost becomes extremely high.

[Object of the Invention] An object of the present invention is to eliminate the above-mentioned drawbacks, promote miniaturization of terminal telephones, and provide a button telephone device that does not increase costs.

[Summary of the Invention] The present invention achieves the above object by providing a voice switch in the office line interface section of the main device instead of a voice switch in each terminal telephone.

[Embodiments of the invention] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a central office line interface section 45 of a key telephone device which is an embodiment of the present invention. Note that the same components as those of the central office line interface section 30 shown in FIG. 5 are given the same reference numerals. 25 is an extension which is a digital line, 34 is a digital interface, 33 is a code/decoder, 35a and 35b are data lines, 36 and 37 are audio switches, 38
is a converter, 39 is a controller that transmits a control signal to control the converter 7, 40 is a receiver, 41 is a transmission line,
32 is a hybrid circuit, and 31 is an analog office line. A terminal telephone (not shown) is connected to the extension 25 via an internal circuit (not shown) in the main device, and a telephone (not shown) is connected to the office line 31 via an exchange (not shown). The office line 31 is a 2-wire analog line, which is converted into a 4-wire line by the hybrid circuit 32.
The data is encoded via the digital interface 34 and connected to an extension line, which is a digital line.

The data line 35a and the data line 35b are connected to a central control unit of the main device (not shown), the data line 35a is a line for transmitting signals from the central control unit to a terminal telephone (not shown), and the data line 35b is a terminal telephone (not shown). It is a line that transmits signals from the central control unit to the central control unit.

The receiver 40 is a line through which the voice signal sent from the office line 31 is transmitted via the hybrid circuit 32, and the transmitter 41 is a line through which the voice signal sent from the terminal telephone (not shown) is transmitted through the hybrid circuit 32 to the office line 31. This is the sending line. The controller 39 is connected to a central control device (not shown), and is configured to operate the converter 38 when making a loudspeaker call with a telephone connected to the central office line of the terminal telephone, and to disable the converter 38 in other cases. This is the line through which signals are sent to control the operation.

FIG. 2 shows a terminal telephone 50 of a button telephone device which is an embodiment of the present invention. Components that are the same as the configuration of the conventional terminal telephone shown in FIG. 4 are designated by the same reference numerals and the explanation thereof will be omitted. Terminal telephone 50 has a configuration in which voice switch 15, voice switch 16, and converter 17 are removed from the configuration of conventional terminal telephone 10 shown in FIG.

In the central office line interface section 45, a terminal telephone 50 connected via an internal circuit (not shown) in the main device is connected to the central office line 31.
When making a loudspeaker call with a telephone connected via an exchange (not shown), a signal is sent via the controller 39 to operate the converter 38, and the converter 38 adjusts the audio level of the handset 40 and the transmission line. 41, and sends a signal to the audio switch 36 and the audio switch 37 to pass the higher audio level and attenuate the lower audio level. Therefore, even if there is a mismatch in the hybrid circuit 32, howling can be prevented from occurring when making a loudspeaker call with a telephone connected to the central office line 31.

As described above, according to this embodiment, the voice switch is provided in the office line interface section of the main device instead of providing the voice switch in the terminal telephone, so that the terminal telephone can be made smaller by the size of the voice switch. Furthermore, since the number of office lines connected to the main device is smaller than the number of terminal telephones, there is an advantage that fewer voice switches are required.

[Effects of the Invention] As described in detail above, according to the present invention, a voice switch is provided in the office line interface section of the main device instead of a voice switch in each terminal telephone. Therefore, a button telephone device can be obtained which can promote downsizing of the terminal telephone by not providing a voice switch. In addition, since the number of connected central office lines in a button telephone device is usually smaller than the number of terminal telephones, the number of voice switches that need to be installed can be reduced, making it possible to obtain a button telephone device that does not require high costs. can.

[Brief explanation of drawings]

FIGS. 1 and 2 show a central office line interface section 45 and a terminal telephone 50 of a button telephone device which is an embodiment of the present invention.
3 is a block diagram showing the configuration of a general key telephone device, and FIGS. 4 and 5 are block diagrams showing the terminal telephone 10 and central office line interface unit 20, respectively, in the conventional key telephone device. It is a diagram. 25... Extension, 31... Office line, 32... Hybrid circuit, 33... Code/decoder, 34... Digital interface, 36, 37... Audio switch,
38...Converter, 39...Controller, 40...Telephone receiver, 41...Transmitter■

Claims (1)

[Claims] In a button telephone device which transmits voice signals between a terminal telephone and a main device and within the main device via a digital line and has a loudspeaker call function, an audio switch is provided in an analog central office line interface section of the main device, The button telephone device is characterized in that the voice switch is operated when the loudspeaker call function is used via the office line interface section, and the voice switch is inactivated when the handset call function is used. .