JPS61184029A - Loudspeaker telephone set - Google Patents

Abstract

PURPOSE:To recognize a proper talking sound volume by adding a switch by which a signal of a prescribed level from a signal generating means is listened to through a speaker. CONSTITUTION:When no reception signal A exists and the user of a loudspeaker changes an output of a sound volume adjusting controller 11, a control circuit 12 detects the absence of the reception signal A and the change in the output of the controller 11 to close a switch 14 and apply control that the attenuation of a reception attenuator circuit is adjusted until the output change in the controller 11 is lost. Thus, a signal B for sound volume confirming tone generated by a sound volume confirming tone generating circuit 13 is inputted to a speaker 10 and the sound volume confirming tone is listened to. The reception sound volume is known while the sound volume is adjusted even when no reception signal exists depending on the sound volume confirming tone.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a public address telephone.

[Conventional technology]

FIG. 2 is a diagram showing an example of a conventional loudspeaker telephone, and the audio signal picked up by the microphone 1 is
Microphone amplifier circuit 2. Transmission attenuator 8. Transmitting amplifier circuit 4. It is sent to the line end 6 through the hybrid circuit 5. On the other hand, the reception signal (hereinafter referred to as A) that has arrived at the line end 6 is transferred to the hybrid circuit 5. Receiving amplifier circuit 7. Receiving attenuator 8. The sound is amplified by the speaker 10 through the speaker amplifier circuit 9.

The output of the transmitting amplifier circuit 2 and the output of the receiving amplifier circuit 7 are input to the control circuit 12a together with the output of the volume mB controller 11, and the control circuit 12a controls the transmitting attenuator 8. The reception attenuator 8 is controlled.

In such conventional loudspeaker telephones, even if the volume adjustment controller 11 is operated when there is no reception signal A, the user has no way to know the optimum level of reception volume.

[Problem that the invention seeks to solve]

Therefore, the above-described conventional loudspeaker telephone has the inconvenience of being unable to confirm whether or not the listening volume is appropriate unless the user waits for the reception signal to arrive.

SUMMARY OF THE INVENTION An object of the present invention is to provide a loudspeaker telephone set that can determine the optimal listening volume even when there is no receiving signal, in the same way as when a receiving signal is received.

[Means for solving problems]

The loudspeaker telephone according to the present invention includes a signal generating means that outputs a signal at a preset constant level, and a signal generating means that outputs a signal at a predetermined level, and a control means that closes the telephone when there is no receiving signal and the output of the volume adjusting means is changing. However, a switch is added to allow a signal at a constant level from the signal generating means to be heard through a speaker.

Therefore, when there is no receiving signal, the user of the loudspeaker telephone listens to the signal from the signal generating means through the speaker and changes the output of the volume adjusting means to achieve the same reception as when the receiving signal is received. The volume can be adjusted to the desired amount.

[Embodiments] Hereinafter, embodiments of a loudspeaker telephone according to the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a loudspeaker telephone according to the present invention.

In addition to the configuration of the conventional loudspeaker telephone described above, the loudspeaker telephone according to this embodiment further includes a volume confirmation sound generation circuit 18 and a swing f14. The volume confirmation sound generation circuit 18 generates a volume confirmation sound signal B at a constant level, and sends this signal B to the receiver amplifier circuit 7 via the switch 14. The switch 14 is a normally open switch, and is closed under the control of the control circuit 1z only when there is no reception signal A and the output of the volume adjustment controller 11 is changing.

Therefore, both the reception signal A and the volume confirmation sound signal B are not input to the reception amplifier circuit 7 at the same time. Note that a synchro transmitter, for example, is used as the volume adjustment controller 11, and a synchro receiver corresponding to the transmitter is disposed in the receiver attenuator 8. In this case, when the user of the public address telephone adjusts the rotation angle of the rotor of the synchro transmitter, the rotation angle of the rotor of the synchro receiver disposed in the receiver attenuator 8 is also adjusted according to this rotation angle. As a result, the amount of attenuation of the signal B of the volume confirmation sound is increased.

Next, an explanation will be given of the operation when the user of the loudspeaker telephone changes the output of the volume adjustment controller 11 when there is no reception signal A.

Receiving a call (if there is no person No. 2, the user of the public address telephone
tji, when the output of the one-section controller 11 is changed, the control circuit 12 detects that there is no receiving signal A and that the volume adjustment fj!
I4+]J i4e 11 is detected to have a change in its output, the switch 14 is closed, and the attenuation amount of the receiver attenuator circuit 8 is controlled to be adjusted until there is no change in the output of the volume adjustment controller 11. do.

Therefore, the volume confirmation sound signal B generated by the volume confirmation sound generation circuit 18 is transmitted to the switch 14. Receiving amplifier circuit 7. Receiving attenuator 8. The sound is input to the speaker 10 through the speaker amplifier circuit 9, and the volume confirmation sound is heard from the speaker 10. This volume confirmation sound allows the user of the loudspeaker telephone to know the volume of the conversation without having to adjust the volume even when there is no reception signal.

When the user of the loudspeaker telephone stops changing the output of the volume adjustment controller 11 when there is no receiving signal, the control circuit 12 stops adjusting the attenuation amount of the receiving attenuator circuit 8 and opens the switch 14. to stop sending out the volume confirmation sound signal B to the speaker amplifier circuit 9. The loudspeaker telephone then shifts to a normal conversation state.

〔Effect of the invention〕

As explained above, the loudspeaker telephone set according to the present invention has the advantage that even when there is no receiving signal, the optimal listening volume can be known in the same way as when the receiving signal is arriving.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a loudspeaker telephone according to the present invention, and FIG. 2 is a block diagram showing a conventional loudspeaker telephone. 7... Receiving amplifier circuit. 10...Speaker. 11... Volume adjustment controller. 1.2...Control circuit. 18...Volume confirmation sound generation circuit. 14...Switch. A: Receiving signal. B...Volume confirmation sound signal. %tF Applicant NEC Corporation Representative Patent Attorney Uchihara Syllable
1 figure

Claims (1)

[Scope of Claims] A loudspeaker telephone comprising a volume adjusting means and a control means for controlling the volume of a received voice from a speaker based on the output of the volume adjusting means when a received voice signal is received, comprising: a preset constant level; a signal generating means for outputting a level signal; and a signal generating means that is closed under control from the control means when there is no received signal and the output of the volume adjusting means is changing, and a signal generating means that outputs a constant level signal from the signal generating means; 1. A loudspeaker telephone set further comprising a switch for allowing a high-level signal to be heard through the speaker.