JPS60114056A - Loudspeaking telephone - Google Patents

Abstract

PURPOSE:To let a user notice a surrounding noise level and enable him to make an appropriate voice level call by providing a level meter indicating peripheral noise levels to a loudspeaking telephone set. CONSTITUTION:Transmission rectification output of a transmission rectification circuit 11 drives a level meter 15 through a meter driving amplifier circuit 14. In normal condition of distinguishing a periphery noise from sound signals, an easy noise meter can be constituted, which indicates noise levels to be inputted in a microphone 1 on a level meter 15 by giving characteristics analogous to audible sense correction characteristics A of JIS C1502 to frequency characteristics of the circuit 11 because accoustic energy of the periphery noise is in most part contained in a low frequency area. Therefore, in case of a user not uttering any sound, the user can know proper sound level because the meter 15 displays the periphery noise level collected.

Description

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

Prior Art Conventionally, the configuration of this type of loudspeaker telephone is the same as the block diagram of the embodiment of the present invention shown in FIG. 1, except that the amplifier circuit 14 and the level meter 15 are omitted.

Therefore, there is no way to compare the level of the audio signal emitted by the user with the level of ambient noise and check whether or not it is converted to an appropriate transmitting audio signal level and sent to the line. (1) Continuing to speak without realizing that an excessive voice signal is being transmitted from the loudspeaker telephone onto the line.

(2) Contrary to the drawback mentioned in (1) above, the user continues to speak without noticing that insufficient audio signals are being transmitted from the loudspeaker telephone.

(3) When using a public address telephone in a place where there is a lot of ambient noise, the user continues to speak without noticing that the level of the voice signal is drowned out by the ambient noise.

There were drawbacks such as.

OBJECTS OF THE INVENTION An object of the present invention is to provide a loudspeaker telephone that solves the above-mentioned drawbacks by equipping the loudspeaker telephone with a level meter that displays the level of ambient noise.

Structure of the Invention In order to achieve the above-mentioned object, the present invention connects a microphone to a microphone amplification circuit, a transmitting voice switch circuit,
The outgoing communication path goes through the amplifier circuit and the hybrid circuit to the line connection terminal, and the hybrid circuit from the line connection terminal.
A receiving speech path where the sound is amplified from a speaker through a receiving amplifier circuit, a receiving audio switch circuit, a speaker amplifier circuit, a transmitting rectified output that is amplified by a microphone amplifier circuit and rectified by a transmitting rectifier circuit, and a receiving amplifier circuit. Amplifying circuit for amplifying the rectified transmitting output; , and a level meter that visually displays the output of this amplifier circuit.

Example Next, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 1, an embodiment of the invention includes a transmitting path, a receiving path, a comparison control circuit, and a signal level circuit.

Regarding the outgoing call path, the voice signal emitted by the user is converted into a outgoing signal by the microphone 1, amplified by the microphone amplifier circuit 2, passed through the outgoing voice switch circuit 3, and then sent to the outgoing amplifying circuit 4. The signal is further amplified and transmitted to the line from the line connection terminal 6 via the hybrid circuit 5.

On the other hand, regarding the reception channel, the reception signal that reaches the line connection terminal 6 passes through the hybrid circuit 5, is amplified by the reception amplifier circuit 7, passes through the reception audio switch circuit 8, is further amplified by the speaker amplifier circuit 9, and is further amplified by the speaker amplifier circuit 9. It is then converted into an audible signal.

Regarding the comparison control circuit 12, the microphone amplifier circuit 2
The transmitting signal amplified by the transmitting rectifier circuit 11 is rectified and smoothed and input, and the receiving signal amplified by the receiving amplifier circuit 7 is rectified and smoothed by the receiving rectifier circuit 13 and input. be done.

Here, the comparison control circuit 12 compares the magnitude of the transmitting rectified output of the transmitting rectifier circuit 11 and the receiving rectified output of the receiving rectifier circuit 13, and then selects the transmitting voice switch circuit 3 and the receiving voice switch circuit. 8 and is controlled in a complementary manner.

Next, regarding the signal level circuit, the sending rectification output of the sending rectifying circuit 11 drives the level meter 15 via the meter driving amplifier circuit 14.

Normally, in this type of loudspeaker telephone, when detecting and distinguishing between ambient noise and voice signals, the acoustic energy of the ambient noise is mostly contained in the low frequency region, so the frequency of the transmitting rectifier circuit 11 is Characteristically, 800-1000Hz
A simple method for displaying the noise level input to the microphone 1 on the level meter 15 by giving a characteristic similar to the hearing correction characteristic A of JI8 C1502, which is determined to reduce the sensitivity as the frequency becomes lower at the following frequencies. A sound level meter can be configured.

For this reason, when the user does not make a sound, the level meter 15 displays the level of the ambient noise picked up by the microphone 1, and the level meter 15 displays the level of the ambient noise picked up by the microphone 1, and the level meter 15 indicates the level at which the user should make the sound under that ambient noise. By looking at the level meter 15, the user can check whether the level of his or her own voice is being converted into a transmission signal relative to the level of surrounding noise.

Effects of the Invention As explained above, according to the present invention, a simple sound level meter is constructed by equipping a loudspeaker telephone with a level meter, so that the user can know the noise level of the surrounding environment and This has the effect of allowing calls to be made at an appropriate voice level at all times.

[Brief explanation of the drawing]

FIG. 1 is a four-dimensional diagram showing an embodiment of the present invention. 1... Microphone, 2... Microphone amplification circuit, 3... Transmission audio switch circuit,
4... Sending amplifier circuit, 5... Hybrid circuit, 6°°°゛°゛ line connection terminal, 7...
- Receiving amplifier circuit, 8... Receiving audio switch circuit, 9... Speaker amplifying circuit, 10... Speaker, 11... Transmitting rectifier circuit, 12... ...
・Comparison control circuit, 13...Receiver rectifier circuit, 14
...Amplification circuit, 15He...Level meter〇

Claims (1)

[Claims] A transmitting speech path from the microphone through the microphone amplification circuit, a transmitting voice switch circuit, an amplifier circuit, and a hybrid circuit to the 5-line connection terminal, and a receiving voice switch circuit from the line connection terminal through the hybrid circuit and the receive amplifier circuit. , the receiving communication path where the sound is amplified from the speaker via the speaker amplifier circuit, the transmitting rectified output which is amplified by the microphone amplifier circuit and rectified by the transmitting rectifying circuit, and the receiving rectifying output which is amplified by the receiving amplifier circuit and is amplified by the receiving rectifying circuit. a comparison control circuit that takes in the rectified receiving rectified output and compares the magnitude of the transmitting rectified output and the receiving rectified output to complementarily control the transmitting audio switch circuit and the receiving audio switch circuit; 1. A loudspeaker telephone comprising: an amplifier circuit for amplifying the transmitting rectified output; and a level meter for visually displaying the output of the amplifier circuit.