JPS5951646A - Loudspeaker telephone set - Google Patents

Abstract

PURPOSE:To smooth a call, by superimposing a DC bias being a threshold value or over capable by set to any of incoming and calling waiting state, so as to reduce the frequency of switching of the calling state of a loudspeaker telephone set at an idle state and to uniform the switching frequency. CONSTITUTION:A DC bias generating circuit is capable of switching and connecting to adders 12, 13 by a switch 14. In setting the switch 14 into a restoring state, the circuit 11 is connected to the adder 12 to be incoming waiting state, and in setting the switch 14 in the operating state, the circuit 11 is connected to the adder 13 to be the calling waiting state. The loudspeaker telephone set is set to any of the incoming and calling waiting state by operating the switch 14. Thus, the frequency of switching of the loudspeaker device at a call is reduced by setting the device to the waiting state suitable for the operating state.

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention relates to a public address telephone system, in particular, a system in which a transmitting level signal and a receiving level signal are input to a comparator, and the level difference between the two fli signals is predetermined. 1y41 is applied to a loudspeaker telephone device that controls the loss value of the variable loss circuit provided in the transmitting amplifier circuit and the receiving amplifier circuit, respectively, when the dark value is exceeded.

(bl Background of the Technology) Instead of the handset and receiver in 1W telephones, loudspeaker telephone devices that use microphones and speakers are becoming popular. Howling can be suppressed by comparing the levels using a comparator, and if the difference exceeds a predetermined threshold, the loss value of the variable loss circuit inserted in the transmitting amplifier circuit and the receiving amplifier circuit is controlled. It is known to provide audio sinch circuits to prevent this.

In such a loudspeaker telephone device, in a non-call state where neither the transmitting level signal nor the receiving level signal is input, the transmitting variable loss circuit inserted in the transmitting amplifier circuit is set to high loss.
When setting the receive variable loss circuit inserted in the receive amplifier circuit to a receive standby state that maintains low loss, and when setting the receive variable loss circuit inserted in the receive amplifier circuit to high loss, and when setting the receive variable loss circuit inserted in the receive amplifier circuit to high loss. There are three types: when setting the transmitting standby state to maintain the transmitting loss circuit at low loss, and when setting the transmitting standby state to the previous call state. is the most commonly used.

((n) Conventional technology and problems FIG. 1 is a diagram showing an example of a conventional loudspeaker telephone device.

In Figure 1, Micron Noman 1, Amplifier 111M unit 2
and 4, and the transmitting variable loss circuit 3 constitute a transmitting amplifier circuit, and the amplifiers 6 and 8, the receiving variable loss circuit 7, and the speaker 9 constitute a receiving amplifier circuit. When the sound P1 is input, the transmitted voice signal outputted from the microphone I:JP1 is amplified by the transmitting amplification circuit, and is transmitted through the defense side P1 and Raku5, such as a hybrid transformer, for example. and is transmitted to the other party's telephone (not shown). Further, the reception level signal received from the other party's telephone via the line is amplified by the reception IF+width circuit and output as sound from the speaker 9. The comparator 1o has a transmitter variable t11
The transmitting level signal output from the loss circuit 3 and the variable receiving level signal 1
Compare the reception level signal output from the n loss circuit 7,
When the transmitting level signal is higher than the receiving level signal by a predetermined value or more, the comparator 10 determines that the loudspeaker telephone device is in the transmitting state, and reduces the loss of the transmitting variable loss circuit 3. The loss value of the receiving variable loss circuit 7 is increased. Further, when the receiving level signal is higher than the transmitting level signal by more than the threshold and is in the state of health, the comparator 10 determines that the loudspeaker telephone device is in the receiving state, and the 1ii loss value of the receiving variable loss circuit 7 is determined. Ti4 loss value of the transmitting variable loss circuit 3 is increased. However, in either case, the transmission variable 114
i14 loss circuit 3 and reception variable loss circuit 7 combination 1
11 is set to a high value that does not cause howling in the public address telephone device. Furthermore, in FIG. 1, a DC bias generation circuit 11 is installed that generates a DC bias slightly higher than the dark value (set), and the DC bias is superimposed on the received signal by an adder 12 and then output to the comparator. Even when the loudspeaker telephone device f and ifi is in a no-call state, the DC bias generated by the DC bias generation circuit 11 is input to the receiving signal side, so that the ratio 11 The small IO is the Hj loss M of the receiving variable loss circuit 7.
i is decreased and the loss value of the transmitting variable loss circuit 3 is increased.
At U, set the loudspeaker telephone AA to standby mode.

As is clear from the following description, in some conventional loudspeaker telephone devices, the DC bias generation circuit M311 is connected so that the standby state is set when there is no call. However, when such amplification 7JJ loudspeaker equipment is installed in a large conference room and a small conference room, and a joint meeting is held via both loudspeaker telephone equipment, there are many opportunities for speaking in the large conference room. The loudspeaker telephone equipment installed in the conference room frequently switches from the receiving standby state to the transmitting state, and there are many opportunities for the beginning of the conversation to be cut off due to the delay in the switching operation. In this situation, the indoor noise in each conference room is transmitted along with the transmitted voice to the other conference room only during the transmission, so the sense of discontinuity is particularly emphasized in small conference rooms where there are many opportunities for overhearing. In order to prevent such drawbacks, the loudspeaker telephone equipment installed in large conference rooms can be installed by superimposing a DC bias on the transmission rail signal, as shown in Figure 2.
I am considering setting it to standby mode. However, if such a loudspeaker telephone device is installed in a large conference room, and the small conference room receives the above-mentioned call-waiting message (if a joint meeting is held with a loudspeaker telephone device set to 100%), the small conference room side In order to speak, it is necessary to switch the small conference room side loudspeaker telephone device that is in standby mode to receive a call, and to switch the telephone device in the conference room that is in standby mode to receive a call. The risk of truncating the beginning of speech increases.

td) Object of the Invention The object of the present invention is to eliminate the drawbacks of the conventional loudspeaker telephone equipment as described above, to reduce switching of the call state of the loudspeaker telephone equipment as much as possible, and to realize a means for conducting calls inside the fan. It is in doing.

(e) Structure of the Invention This object is to manually input a transmitting rail signal and a receiving rail signal into a comparator, and when the level difference between the two signals exceeds a predetermined value, In a loudspeaker telephone device that controls the Ti4 loss value of variable loss circuits provided in the amplifier circuit 3 and the receiver amplifier circuit, either the transmitting level signal input to the comparator or the receiving level serve,
The loudspeaker telephone equipment jf7 is selected at will and is in the jjiE call state.
This is achieved by providing means for superimposing a DC bias equal to or higher than the dark value, which can be set to either a receiving standby state or a transmitting standby state.

([1 Examples of the invention An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a diagram showing a loudspeaker telephone device according to an embodiment of the present invention. Note that the same reference numerals indicate the same objects throughout the figures. In FIG. 3, the DC bias generation circuit 11 is connected to an adder 12 provided at the receiving level signal input end of the LTI articulator 10 and an adder 13 provided at the transmitting level signal input side by a switch 14. It is said that it is possible to switch to and connect to. When the switch 14 is set to the recovery state, the DC bias generation circuit 11 is connected to the adder 12, so the loudspeaker telephone device enters the standby state for receiving a call, as shown in FIG. 1, and the switch I4 is set to the operating state. If set to , the DC bias generation circuit 11 is connected to the adder 13, so that the loudspeaker telephone device enters a call standby state, similar to J in FIG. Such a loudspeaker telephone device is installed in the large conference room and the small conference room, and the switch 1 of the loudspeaker telephone device on the large conference room side is connected.
4 is activated to set the telephone to a transmitting standby state, and the switch 14 of the small conference room side loudspeaker telephone device is restored to a receiving standby state. This eliminates the need for the large conference room side loudspeaker telephone device to switch the call state every time a person speaks, reducing the chance of disconnection at the beginning of a conversation, and reducing the feeling of discontinuity in the small conference room side. On the other hand, when speaking from the small conference room side, if you operate the switch 14 of the small conference room side loudspeaker telephone device in advance to put it into the transmitting standby state, then only the large conference room side loudspeaker telephone device will change from the transmitting standby state. Since the state is switched to the receiving state, the risk of occurrence of disconnection at the beginning of the conversation is reduced. Furthermore, if the large conference room side detects the speech from the small conference room side and restores the loudspeaker telephone device switch 14 on the large conference room side and then sets it to the incoming call standby state, the small conference room side's remarks can be made even more smoothly. be exposed.

As is clear from the above description, according to the present embodiment, by operating the switch 14, the loudspeaker telephone device can be set to the receiving standby state and the call 1.1 machine state. Therefore, by setting the standby state each time to suit the state of use, the frequency of switching the loudspeaker telephone device during a call can be sufficiently reduced.

It should be noted that FIG. 3 is only one embodiment of the present invention, and the configuration of the loudspeaker telephone device is not limited to that shown in the figure, and many other modifications may be considered. In this case, the effects of the present invention remain the same. In addition, the use of loudspeaker telephone equipment is not limited to joint meetings held in room 8L of large and small meetings, but can also be used to facilitate calls between rooms with high indoor noise levels and rooms with low indoor noise levels. Used effectively. In such a case, the loudspeaker telephone equipment installed in the former is set to the receiving standby state, and the latter is set to the transmitting standby state, so that the voice switch due to the difference in the noise 9! The imbalance in J.J.'s work can be corrected.

(g) According to the present invention, the standby state of the loudspeaker telephone device can be set to 11 (standby state at the time of a call) depending on the state of use, so that the loudspeaker telephone device can be used for making calls. A call is placed on the phone by reducing the frequency of state switching or by balancing the switching action.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a conventional loudspeaker telephone device, FIG. 2 is a diagram showing another example of a conventional loudspeaker telephone device, and FIG. 3 is a diagram showing a loudspeaker telephone device according to an embodiment of the present invention. be. In the figure, 1 is a microphone, 2, 4, 6 and 8 are amplifiers, 3 is a transmission variable IB loss circuit, 5 is a side sound protection circuit, and 7
1 is a receiving variable tkI loss circuit, 9 is a speaker, 10 is a comparator, 11 is a DC bias generation circuit, 12 and 13 are adders, and 14 is a switch.

Claims (1)

[Claims] Input the transmitting level signal and the receiving level signal to a comparator,
In the loudspeaker telephone device, the comparator controls the loss value of the variable loss circuit provided in the transmitting amplifier circuit and the receiving amplifier circuit, respectively, when the level difference between the two signals exceeds a predetermined value. A value equal to or higher than the above-mentioned dark value can be set by arbitrarily selecting one of the transmitting level signal and the receiving level signal inputted to the input terminal, and setting the loudspeaker telephone device in the no-call state to either the receiving standby state or the transmitting standby state. A loudspeaker telephone device characterized by being provided with means for superimposing a DC bias.