JPS6339248A - Telephone set sensitive to peripheral noise - Google Patents

Abstract

PURPOSE:To automatically adjust the sound volume of an incoming call at an appropriate level corresponding to the magnitude of peripheral noise by permitting a rectifying and smoothing means where a charging time constant is set larger than a discharging time constant to rectify and smooth a noise detection signal, and changing and controlling the level of an incoming call signal. CONSTITUTION:A microphone amplifier 8 amplifies noise collected by a microphone 7 built-in a telephone set 10. The rectifying and smoothing circuit 9 converts the noise to a DC voltage value in proportion to the level of its sound pressure, and inputs the converted one to a multiplier circuit 6. The rectifying and smoothing circuit 9 with charging in a long time and discharging in a short time outputs a voltage roughly equal to the level of peripheral noise independent of sound that human being speaks and sudden noise. Thus, as the peripheral noise becomes larger, the voltage value of the rectifying and smoothing circuit 9 is boosted, and the output of the multiplier circuit 6 becomes larger than multiplication. The sound volume of the incoming call signal rises because said signal drives a speaker 5 through a speaker amplifier 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a general telephone set, and more particularly to a standalone telephone set composed of an electronic circuit.

[Conventional technology] An example of this type of telephone is shown in FIG.

In the same figure, a capacitor 2 and the primary winding of a transformer 3 are inserted and connected between the line terminals 1, the output of the secondary winding of the transformer 3 is amplified by a speaker amplifier 4, and the ring tone is transmitted to a speaker 5. It is set to play.

Conventionally, the volume of the ring tone of this type of electronic telephone set has been adjusted by the person using the telephone using a volume or a switch (not shown) of the telephone set.

[Problems to be solved] In the conventional telephones mentioned above, the volume of the ringtone is adjusted by the person using the telephone using the volume or a switch, so the adjustment must be done in a quiet environment. When a telephone is used in a room with increased ambient noise, the ringtone is masked by the surrounding noise due to the masking effect, making it difficult to reliably recognize the ringtone.

In this case, it would be possible to detect the surrounding noise of the phone and automatically adjust the volume of the ringtone based on this, but since the detected noise includes human speech and sudden noises, With such simple detection, it has not been possible to provide a highly practical ambient noise sensitive telephone.

Therefore, one purpose of the present invention is to accurately detect the noise surrounding the telephone, and automatically adjust the volume to an appropriate level that allows the ringtone to be heard, depending on the level of this noise. An object of the present invention is to provide an ambient noise sensitive telephone set capable of detecting ambient noise.

[Means for Solving Problems] In order to achieve the above object, the present invention includes a detection means for detecting noise around the telephone, and an integrating circuit in which a charging time constant is set larger than a discharging time constant. a rectifying and smoothing means for rectifying and smoothing the detection signal from the detecting means; and a signal level variable means for variably controlling the level of the young signal based on the signal from the rectifying and smoothing means. There is.

[Example] Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of a telephone a10, which is an embodiment of the present invention.

In the figure, a capacitor 2 and the primary side a line of a transformer 3 are inserted and connected between the line terminals 1, and the secondary winding output of the transformer 3 is one of the multiplication circuits 6, which is an example of signal level varying means. It is designed to be input to the input terminal of.

On the other hand, a microphone 7 as an example of a detection means for detecting ambient noise of the telephone 10, a microphone amplifier 8 for #3Il1g the detection signal of the microphone 7, and a rectification and smoothing means for rectifying and smoothing the amplified output and converting it into a DC voltage. A rectifying and smoothing circuit 9 is provided, and the output of this rectifying and smoothing circuit 9 is inputted to the other input terminal of the multiplication circuit 6.

The multiplication circuit 6 records the output of the transformer 3 and I).
! ! The signal is multiplied by the output of the i-stream smoothing circuit 9 and output, and the speaker amplifier 4 amplifies this to reproduce the ring tone on the speaker 5.

Here, in the rectifying and smoothing circuit 9, a time constant is provided by an integrating circuit made up of a resistor and a capacitor, and in a charging state, charging is performed for a long time with high resistance, and in a discharging state, a short time is performed using a low resistance. It is now charging.

An example of the rectifying and smoothing circuit 9 that performs such charging and discharging is shown in FIG.

In FIG. 2, this rectifying and smoothing circuit 9 includes an arithmetic circuit 21
．． Diode 22. Resistor 23.24 and capacitor 2
5, the output from the microphone amplifier 8 is inputted through an input terminal 20, rectified and smoothed, and outputted from an output terminal 26. Here, the resistance 23.24
and capacitor 25 constitute the above integration circuit.

The resistance value of the resistor 23 is RI + the resistance value of the resistor 24 is R2
, when the capacitance of the capacitor 25 is C, at the output terminal 26, the charging time constant (charging time) for charging the capacitor C is R2XC, the discharging time constant (charging time) for discharging it is R+XC, and R1<< By satisfying the condition No. 112, the above operation can be realized.

The operation of the telephone IO configured as above will be explained.

When an incoming signal arrives on the line, the 1687 AC signal of the incoming signal passes through the capacitor 2 and is input to the multiplication circuit 6 via the transformer 3.

On the other hand, ambient noise collected by the microphone 7 built into the TL speaker is moderately amplified by the microphone amplifier 8, and then converted to a DC voltage value proportional to the sound pressure level of the noise by the rectifier and smoothing circuit 9. It is converted and input to the multiplication circuit 6.

Here, due to the circuit configuration of the rectifying and smoothing circuit 9 described above,
The reason why ambient noise (indoor background noise) can be detected separately from human speech or sudden noise will be explained below.

Ambient noise (indoor background noise) is always present at a steady level, so its sound pressure level is also approximately constant. Therefore, when detecting long-term charging where the charging time is long, this steady ambient noise level appears as a rectified and smoothed voltage value.

On the other hand, human speech or sudden noise (noise)
Even if it lasts for a long time, it continues for about 3 to 4 seconds and is interrupted periodically, so the voltage value of rectification and smoothing is reset by short-time discharge.

Figure 3 shows an example of changes over time in the sound pressure level of ambient noise and the accompanying rectified smoothed voltage. In the figure, the solid line indicates the ambient noise, and the broken line indicates the rectified smoothed voltage. .

In the same figure, in the section marked ■, the rectified and smoothed voltage charged for a long time is slowly charged as the surrounding noise increases, and
At the point in time, the level of the ambient noise and the rectified smoothed voltage become equal. If the ambient noise temporarily decreases at the time of ■,
The short-time discharge causes the rectified and smoothed voltage to immediately drop to the background noise level. Furthermore, as shown in (2), human speech that lasts for several seconds or sudden noises are hardly affected by the rectified and smoothed voltage.

In this way, by using a rectifying and smoothing circuit that can charge for a long time and discharge for a short time, the output voltage level can be
It outputs a voltage approximately equal to the level of ambient noise that does not depend on human speech or sudden noise, making it possible to distinguish between ambient noise (indoor background noise) and human speech or sudden noise (noise). It becomes possible.

The output of this rectifying and smoothing circuit 9 is input to one of the input terminals of the multiplication circuit 6.

Since the output voltage EO of the multiplication circuit 6 is the product of the signals from the two input terminals, it is expressed as Eo=X·Y. However, X=Wakanobu signal, Y=fi flow mossion output voltage.

Here, although the incoming signal X is at a constant level, the output voltage Y of the rectifying and smoothing circuit 9 varies depending on the ambient noise as described above.

That is, as the ambient noise increases, the voltage value of the rectifying and smoothing circuit 9 increases, so the output of the multiplication circuit 6 increases by multiplying by one.

Since this signal drives the speaker 5 via the speaker Φ amplifier 4, the volume of the incoming signal increases.

Conversely, when the ambient noise decreases, the output voltage of the rectifying and smoothing circuit 9 decreases, so the output of the multiplication circuit 6 also decreases, and as a result, the volume of the first incoming signal also decreases.

As described above, according to the telephone according to the present embodiment, the volume of the incoming signal can be controlled to an adaptive level in proportion to the level of ambient noise.

Note that the present invention is not limited to the above embodiments.
Various alternative implementations are possible within the scope of the invention.

The charging time constant and discharging time constant in the rectifying and smoothing circuit can be set in various ways depending on the duration of the noise to be removed from the surrounding noise, etc., and it is sufficient that the charging time constant is set larger than the discharging time constant.

Further, as a signal level varying means, the above-mentioned multiplication circuit 6
In addition to the above, it is possible to adopt various 4Is that variably control the level of the incoming signal based on the output signal from the rectifying and smoothing means.
For example, it may be a variable gain amplifier that varies the amplification gain of the incoming signal based on the output signal of the rectifying and smoothing means.

[Effects of the Invention] As explained above, according to this embodiment, the noise detection signal from the detection means is rectified and smoothed by the rectification and smoothing means in which the charging time constant is set larger than the discharging time constant. It is possible to separate only the ambient noise level that does not depend on human speech or sudden 31fg, and by variably controlling the level of the incoming signal using a signal that corresponds to this ambient level, the level of the incoming signal can be variably controlled to You can also adjust the ringtone volume to the appropriate level.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a telephone that is an embodiment of the present invention;
The figure is a circuit diagram showing an example of a rectifying and smoothing circuit. Figure 3 is a characteristic diagram showing the charging and discharging characteristics of the rectifying and smoothing circuit.
The figure is a configuration diagram showing an example of a conventional telephone. 6: Signal level variable means 7: Detection means 9: Rectification and smoothing means

Claims (3)

[Claims] (1) Equipped with a detection means for detecting the noise surrounding the telephone, and an integrating circuit in which a charging time constant is set larger than a discharging time constant, and rectifying and smoothing the detection signal from the detection means. 1. An ambient noise sensitive telephone set comprising a rectifying and smoothing means and a signal level variable means for variably controlling the level of an incoming signal based on a signal from the rectifying and smoothing means. (2) The ambient noise sensitive telephone set according to claim 1, wherein the signal level variable means is a multiplication circuit that multiplies the incoming signal by the output signal of the rectifying and smoothing means. (3) The ambient noise sensitive telephone set according to claim 1, wherein the signal level variable means is a variable gain amplifier that varies the amplification gain of the incoming signal based on the output signal of the rectifying and smoothing means.