JPH0472945A - Key telephone system - Google Patents

Abstract

PURPOSE:To attain talking with a proper sound volume at all times by decreasing the sound volume from a speaker when a received sound volume of a voice signal inputted from a trunk line is larger than a reference value and increasing the sound volume when the voice signal is smaller than the reference value. CONSTITUTION:When a voice signal on a trunk line is inputted to an A/D converter circuit 18, the inputted analog signal is quantized by a sampling frequency signal set by a timer 19 and the result is stored in a memory in an arithmetic circuit 20 together with a timer value. The arithmetic circuit 20 calculates a range of the voice signal and a sound volume of the voice signal from the input value from the A/D converter circuit 18 and the timer 19 and compares it with a reference value in the memory. When the calculated reception sound volume is deviated from the reference value, a difference signal from the reference value is inputted to a reception sound volume amplifier gain control circuit 21 to control the gain of a speaker amplifier 16 so that the reception sound volume outputted from a speaker 17 is always nearly equal to the reference value.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a button telephone device that can appropriately set the listening volume during a telephone call on a central office line.

BACKGROUND OF THE INVENTION Conventionally, with this type of button telephone device, the user has been able to adjust the listening volume to his or her preference when making a call on a central office line.

FIG. 5 shows the configuration of a reception volume setting device in a conventional key telephone device of this type. In FIG. 5, reference numeral 1 denotes a DC circuit connected to the office line, which detects incoming calls from the office line. 2 is a BN (balance network) circuit, which prevents crosstalk between the microphone 4 and the speaker 7. 3 is BN
This is a microphone amplifier connected between the circuit 2 and the microphone 4. Reference numeral 5 denotes a voice band filter, which sends a voice band signal to a speaker 7 via a speaker amplifier 6. 8 is a receiving volume amplifier gain control circuit for controlling the speaker amplifier 6. A switch detection circuit 9 reads the amplification factor set by the listening volume setting switch 10 and controls the listening volume amplifier gain control circuit 8.

Next, the operation of the conventional example will be explained. In Figure 5, when an incoming call is received through the central office line, the incoming call is sent to the DC circuit 1.
The received sound volume amplifier gain control circuit 8 adjusts the gain of the speaker amplifier 6 according to the amplification factor set by the received sound volume setting switch 10. By making the adjustment, the sound with the adjusted volume is transmitted from the speaker 7 to the user's ears. Therefore, when the volume transmitted from the speaker 7 is low, set the listening volume setting switch 10 so that the amplification factor is high, and conversely, when the listening volume is high, set the listening volume setting switch 10 so that the amplification factor is low. adjust.

In this way, even with the conventional key telephone device, the user can speak at a desired volume by adjusting the listening volume setting switch.

Problems to be Solved by the Invention However, with the conventional button telephone device, if the listening volume for a central office line call is low due to a long-distance call, etc., the user must adjust the listening volume for each call. There was a problem.

SUMMARY OF THE INVENTION The present invention solves these conventional problems, and aims to provide an excellent key telephone device that allows a user to always make telephone calls at an appropriate volume.

Means for Solving the Problems In order to achieve the above object, the present invention provides a filter means for limiting the audio frequency band for measuring the volume of the received voice, and a means for determining the volume of the voice received from the outputted audio signal. ,
The device includes means for comparing the obtained listening volume with a reference value and appropriately controlling the gain of the speaker amplifier so that the listening volume output from the speaker is approximately equal to the reference value.

The present invention also includes means for arbitrarily and variably setting the reference value of the listening volume to a level desired by the user.

According to the above-described configuration, the present invention reduces the volume output from the speaker when the volume of the voice signal input from the central office line is higher than the reference value, and reduces the volume output from the speaker when the volume of the voice signal input from the central office line is lower than the reference value. You can increase the volume and always talk at a uniform volume.

The present invention also allows the user to set the reference value to the volume desired by the user, so that the user can always talk at the volume desired by the user.

Embodiment FIG. 1 shows the configuration of a volume setting device in a key telephone device showing a first embodiment of the present invention.

In FIG. 1, reference numeral 11 is a DC circuit connected to the office line, which detects incoming calls from the office line. 12 is a BN (balanced network) circuit, which includes a microphone 14 and a speaker 17;
prevent crosstalk with 13 is a microphone amplifier connected between the BN circuit 12 and the microphone 14.

Reference numeral 15 denotes a voice band filter, which sends a voice band signal to a speaker 17 via a speaker amplifier 16. 18 is an A/D conversion circuit, which quantizes the analog signal from the audio band filter 15. 19 is a timer, A
The input timing from the /D conversion circuit 18 and the sampling frequency of the A/D conversion circuit 18 are given. 20 is an arithmetic circuit (CPU) which calculates the listening volume from the input signals from the A/D conversion circuit 18 and the timer 19, and compares the calculated listening volume with a reference value. 2
Reference numeral 1 denotes a receiving volume amplifier gain control circuit, which controls the speaker amplifier 16 based on the comparison result of the arithmetic circuit 21.

Next, the operation of the above embodiment will be explained. In FIG. 1, when the voice signal on the office line is input as an analog signal to the A/D conversion circuit 18 through the voice band filter 15, the A/D conversion circuit 18 sets the manually input analog signal with the timer 19. It is quantized at the sampling frequency and stored in the memory in the arithmetic circuit 20 together with the timer value. The arithmetic circuit 20 calculates the range of the audio signal and the volume of the audio signal from the input values from the A/D conversion circuit 18 and the timer 19, and compares them with reference values in the memory.

If the calculated listening volume deviates from the reference value, a difference signal from the reference value is input to the listening volume amplifier gain control circuit 21, which controls the gain of the speaker amplifier 16 to adjust the listening volume output from the speaker 17. Control the volume so that it is always approximately equal to the standard.

FIG. 2 shows a second embodiment of the present invention, in which a switch detection circuit 2 is added to the arithmetic circuit 20 of the first embodiment shown in FIG.
2, a listening volume setting switch 23 is added.

In this second embodiment, the listening volume determined by the arithmetic circuit 20 is not compared with a reference value preset in the memory in the arithmetic circuit 2o, but the user can set the listening volume setting switch 23 as desired. is compared with the reference value set in . That is, when the user sets the desired volume using the listening volume setting switch 23, the switch detection circuit 22 detects the amplification factor and inputs it to the arithmetic circuit 20. The calculated listening volume is compared and the difference signal is sent to the listening volume amplifier gain control circuit 21. The listening volume amplifier gain control circuit 21 controls the gain of the speaker amplifier 16 so that the listening volume output from the speaker 17 is approximately equal to the reference value set by the user.

FIG. 3 shows the configuration of a third embodiment of the present invention. Third
In the figure, 31 is a DC circuit connected to the office line,
Detects incoming calls from central office lines. 32 is a BN (balance network) circuit, which prevents crosstalk between the microphone 34 and the speaker 37. 33 is the BN circuit 32 and microphone 3
This is a microphone amplifier connected between 4 and 4. 35
is an audio band filter, which sends audio band signals to the speaker 37 via the speaker amplifier 36. 38 is an integrating circuit which samples the audio signal output from the audio band filter 35 for a certain period of time set by the timer 41 to determine the listening volume. 39 is an integration circuit 38
This is a receiver amplifier that amplifies the output from the receiver, and its gain is controlled by an amplifier gain control circuit 40. 42
is a differential circuit that compares the listening volume output from the listening amplifier 39 with a reference value and calculates the difference. Reference numeral 43 denotes a receiving volume amplifier gain control circuit that controls the gain of the speaker amplifier 36 based on the difference signal obtained by the difference circuit 42.

Next, the operation of the above embodiment will be explained. In FIG. 3, when the audio signal on the office line is input to the integration circuit 38 through the audio band filter 35, the integration circuit 38 integrates the audio signal over the sampling time from the timer 41 to determine the listening volume of the audio signal. . The obtained listening volume is compared with a predetermined reference value in a difference circuit 42, and the difference is calculated by a listening volume amplifier gain control circuit 4.
3 manually controls the gain of the speaker amplifier 36,
Control is performed so that the listening volume output from the speaker 37 is always approximately equal to the reference value.

FIG. 4 shows a fourth embodiment of the present invention, in which a switch detection circuit 4 is added to the differential circuit 42 of the third embodiment shown in FIG.
4, a listening volume setting switch 45 is added.

In this fourth embodiment, the listening volume determined by the integrating circuit 38 is not compared with a reference value set in advance in the difference circuit 42, but the user controls the listening volume setting switch 4.
5 is compared with an arbitrarily set reference value. That is, when the user sets the desired volume using the listening volume setting switch 45, the switch detection circuit 44 detects the amplification factor and inputs it to the difference circuit 42, and the difference circuit 42 compares it with the input reference value. The calculated listening volume is compared and the difference signal is sent to the listening volume amplifier gain control circuit 43. The receiving volume amplifier gain control circuit 43 controls the gain of the speaker amplifier 36,
Control is performed so that the listening volume output from the speaker 37 is approximately equal to the reference value set by the user.

1.

In this way, according to each of the embodiments described above, when the voice of the other party is heard on the central office line, the listening volume is controlled so that it is approximately equal to the reference value set in advance or arbitrarily set by the user. Even if the listening volume for a central office line call is inappropriate due to a long-distance call, etc., the user does not need to adjust the listening volume for each call, and can always make calls at an appropriate listening volume. can.

Effects of the Invention As is clear from the embodiments described above, the present invention automatically adjusts the listening volume, and has the advantage that the listening volume can always be kept at an appropriate level.

The present invention also automatically adjusts the listening volume to the desired volume set by the user, and has the effect that the listening volume can always be maintained at the volume desired by the user.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a reception volume setting device in a button telephone device according to a first embodiment of the present invention, and FIG. 2 is a schematic block diagram of a reception volume setting device in a button telephone device according to a second embodiment of the invention. 3 is a schematic block diagram of a receiving volume setting device in a button telephone device showing a third embodiment of the present invention, and FIG. 4 is a schematic block diagram of a receiving volume setting device in a button telephone device showing a fourth embodiment of the present invention. Schematic Block Diagram FIG. 5 is a schematic block diagram of a receiving volume setting device in a conventional key telephone device. 11... DC circuit, 12... BN (balance network) circuit, 13... Microphone amplifier, 14...
...Microphone, 15...Audio band filter 1
6...Speaker amplifier, 17...Speaker, 18.
...A/D conversion circuit, 19...timer, 20...
Receiving volume amplifier gain control circuit, 21... Arithmetic circuit (CPU), 22... Switch detection circuit, 22
...Receiver volume setting switch. 31... DC circuit, 32... BN (balance network) circuit, 33... Microphone amplifier, 34...
... Microphone, 35 ... Audio band filter, 3
6...Speaker amplifier, 37...Speaker, 38.
...Integrator circuit, 39...Reception amplifier, 40...Amplifier gain control circuit, 41...Timer, 42
... Differential circuit, 43 ... Receiving volume amplifier gain control circuit, 44 ... Switch detection circuit, 45 ...
- Receiver volume setting switch.

Claims (4)

[Claims] (1) The means for keeping the listening volume constant includes a filter means for extracting an audio frequency band during a call, a means for determining the volume of the audio signal after passing through the filter means, and a comparison of the determined volume with a reference value. control means for controlling the gain of the speaker amplifier so that the gain is approximately equal to the reference value. (2) The button telephone device according to claim (1), wherein the means for determining the volume comprises an A/D conversion circuit that quantizes the audio signal after passing through the filter means at a sampling frequency set by a timer. (3) The button telephone device according to claim 1, wherein the means for determining the volume comprises an integrating circuit that samples the audio signal after passing through the filter means for a fixed period of time using a timer. (4) The button telephone device according to claim (2) or (3), further comprising means for arbitrarily variably setting the reference value of the reception volume.