JPH0560293B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a key telephone device with a so-called amplification function that can amplify a received signal.

Conventional configuration and its problems In general, key telephone devices with amplification functions have a changeover switch circuit that compares the received signal and the transmitted signal with each other to prevent howling, and gives priority to the larger signal and passes it through. must be established.

By the way, in this case, the level of the incoming signal varies greatly depending on whether the other party is an extension phone or an outside phone (a phone connected through a central office), and therefore If the above-mentioned switching is configured to be performed normally, there is a problem in that the switching is not performed normally to the other telephone, making it almost impossible to make a call.

OBJECTS OF THE INVENTION The present invention eliminates the above-mentioned conventional drawbacks, and provides an excellent key telephone device that always performs normal switching between transmission and reception, regardless of whether the other party is an internal telephone or an external telephone. The purpose is to

Structure of the Invention In order to achieve the above object, the present invention includes a detection means for detecting whether the other party is an extension telephone or an outside telephone, and switches the switching level of transmission/reception switching depending on the output of the detection means. A switching means is provided so that normal transmission/reception switching can always be performed regardless of whether the other party is an extension telephone or an outside telephone.

DESCRIPTION OF THE EMBODIMENTS The figure is a schematic configuration diagram of an embodiment of the button telephone device of the present invention. In the figure, 1 is a central office line, 2 is a main unit connected to the central office line 1, and 3 and 4 are extension telephones, respectively. It is. 5 is a communication line that connects the main device 2 and the extension telephone 3, 6 is a control line that connects the main device 2 and the extension telephone 3, 7 is a hybrid circuit provided in the extension telephone 3, and 8 is a hybrid circuit. 9 is an amplifier circuit that amplifies the reception signal inputted through circuit 7; 9 is a changeover switch circuit that attenuates the level of the reception signal by the output of comparison circuit 17, which will be described later; 10 is an amplifier circuit that amplifies the output of changeover switch circuit 9. , 11 is a speaker for amplifying the reception signal, 12 is a microphone for outputting a transmission signal, 13 is an amplifier circuit for amplifying the output of the microphone 12, and 14 is for adjusting the level of the transmission signal by the output of a comparison circuit 17, which will be described later. 15 is an amplifier circuit that amplifies the output of the changeover switch circuit 14, and 16 is connected to the main device 2 through the control line 6.
A transmission signal level adjustment circuit 17 attenuates the output of the amplifier circuit 13 to a certain level based on the signal transmitted from the amplifier circuit 8, and 17 inputs the output of the amplifier circuit 8 and the output of the transmission signal level adjustment circuit 16, and compares the two with each other. This is a comparison circuit that

Although the main device 2 is not shown, depending on the dial signal from the extension telephones 3 and 4 or the central office line 1, the communication between the extension telephones 3 and 4 or between the extension telephones 3 and 4 or between the extension telephones 3 and
4 and the central office line 1, and has means for detecting whether the other party is an extension telephone or a central office line (external telephone) from the perspective of the extension telephones 3 and 4. There is. Here, this detection means is based on, for example, the operation results of the communication path forming means in the main device, that is, the operation results such as which extension telephone is connected to which extension telephone, and which extension telephone is connected to which line. , it can be easily configured as a means for determining this. The output of the detection means is configured to be outputted to the control line 6, and the transmitting signal level adjustment circuit 16 is controlled by the output of the detection means outputted to the control line 6. It is composed of

Next, the operation of the above embodiment will be explained. now,
Assume that extension telephone 3 is currently communicating with extension telephone 4. In this case, as seen from the extension telephone 3, the other party is an extension telephone, so an output indicating this is output to the control line 6, and the transmitting signal level adjustment circuit 16 compares the output of the amplifier circuit 13 without attenuating it. Output to circuit 17. Therefore, the comparison circuit 17
As a result, the output of the amplifier circuit 8 and the output of the amplifier circuit 13 are directly compared, and the respective changeover switch circuits 9 and 14 are controlled based on the comparison result.

Next, assume that the extension telephone 3 is talking to a central office line (external telephone). In this case, since the other party is an outside line from the perspective of the extension telephone 3, an output indicating this is output to the control line 6. Therefore, in this case, the transmit signal level adjustment circuit 16 adjusts the output of the amplifier circuit 13 to a predetermined constant level (for example, 5
~10db) and output to the comparator circuit 17. Therefore, in the comparator circuit 17, the output of the amplifier circuit 8 and
The output of the amplifier circuit 13 is compared with a signal attenuated to a predetermined constant level, and the respective changeover switch circuits 9 and 14 are controlled based on the comparison result.

In this way, according to the above embodiment, the level of the transmission signal input to the comparison circuit 17 is switched and adjusted depending on whether the other party is an extension telephone or an outside telephone. This has the advantage that normal transmission/reception switching is always possible regardless of whether the other party is an extension telephone or an outside telephone. In other words, in general, when the other party is an outside line phone, the receiving signal is at a considerably lower level than the sending signal, and if you compare the two directly, even if the sending signal is noisy, it will switch to the sending side, and the receiving signal will be lower than the sending signal. However, according to this embodiment, the level of the transmitting signal is adjusted in advance so that it is at the same level as the received signal and is applied to the comparison circuit, so that the other party can hear the outside line. It has the advantage that normal switching can always be performed whether it is a telephone or an extension telephone.

In the above embodiment, the switching means for switching the switching level for switching between transmission and reception is provided by the transmission signal level adjustment circuit 16.
However, it goes without saying that it may also be constructed using an adjustment circuit that adjusts the received signal level.

Further, although a detailed explanation thereof has been omitted in the above explanation, the changeover switch circuits 9 and 14 are connected to the amplifier circuit 8 when the receive signal and transmit signal input to the comparator circuit 17 are larger than the transmit signal and the receive signal, respectively. ,1
The outputs of the amplifier circuits 8 and 13 are transmitted almost as they are to the amplifier circuits 10 and 15, and when the outputs of the amplifier circuits 8 and 13 are attenuated to a predetermined constant level, they are transmitted to the amplifier circuits 10 and 15. ing.

Effects of the Invention As is clear from the above embodiments, the present invention includes means for detecting whether the other party is an extension telephone or an outside telephone, and switching levels of transmission/reception switching depending on the output of the detection means. This system is equipped with a switching means, and therefore has the advantage that normal transmission/reception switching is always possible, and good communication is always possible regardless of whether the other party is an outside line or an extension line.

[Brief explanation of the drawing]

The figure is a schematic configuration diagram of an embodiment of the button telephone device of the present invention. 1... Office line, 2... Main device, 3, 4... Extension telephone, 5... Call line, 6... Control line, 7... Hybrid circuit, 8, 10, 13, 15... Amplifier circuit, 9, 14...Switch circuit, 11...Speaker, 12...Microphone, 16...Transmission signal level adjustment circuit, 17...Comparison circuit.

Claims (1)

[Claims] 1. A comparison circuit that compares the levels of the transmitting signal and the receiving signal, and as a result of the comparison by this comparison circuit, if the transmitting signal is larger, the receiving signal is compared, and if the receiving signal is larger, the transmitting signal is compared. a detecting means for detecting whether the other party is an extension telephone or an outside telephone; is provided with means for relatively attenuating the incoming signal and, in the case of an outside telephone, a means for relatively attenuating the outgoing signal and applying them to the above-mentioned comparison circuit. A button telephone device configured to function normally.