JPH08149192A - Portable telephone set - Google Patents

Abstract

PURPOSE: To provide a portable telephone set in which a background sound is effectively attenuated without the use of a microphone with high directivity and the voice of a talker is sent with a high S/N. CONSTITUTION: The portable telephone set having a flip is provided with a 1st sound collection microphone 1 provided to one side of the flip, a 2nd sound collection microphone 2 provided to the other side of the flip, and a detection means detecting switching of the flip. When the flip is open, a difference between the sound collection signals of two microphones is obtained by an noninverting amplifier 4, an inverting amplifier 5 and an adder circuit 6 and when a background sound having no difference from the sound collection level is eliminated and only the sound component is obtained as the subtraction result, it is sent through the transmission section 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile phone equipped with a flip, and more particularly to improvement of background sound removal technology during transmission.

[0002]

2. Description of the Related Art A conventional portable telephone equipped with a flip is provided with a microphone for collecting an incoming call which is provided on a surface which is an outer side when the flip is closed and a surface which faces a speaker when the flip is opened. The sound collecting microphone at the time of calling and the switching means for switching the sound input system to the sound collecting microphone at the time of the call when the flip is closed and the sound collecting microphone at the time of the call when the flip is opened by opening and closing the flip.

[0003]

However, in the above-mentioned conventional portable telephone, the background sound is detected together with the voice because the microphone which is generally omnidirectional or has poor directivity is used as the sound collecting microphone. The background sound is heard as noise by the other party.

This causes a problem that the S / N ratio is deteriorated and the voice of the speaker is difficult to hear, especially when the mobile phone is used at a high noise level such as at an intersection. In order to solve the above problems, a method of adopting a microphone having high directivity can be considered, but in that case, the speaker has to bother with the microphone always facing the mouth. It is not appropriate.

In view of the above points, the present invention effectively attenuates background sound without using a microphone having high directivity, and has a high S / N ratio.
It is an object of the present invention to provide an extremely useful mobile phone capable of transmitting a speaker's voice in a ratio.

[0006]

[Means for Solving the Problems] To achieve the above object,
According to the present invention, in a mobile phone equipped with a flip, a first sound collecting microphone provided on one surface of the flip, a second sound collecting microphone provided on the other surface of the flip, and It is provided with a detecting means for detecting opening / closing and a subtracting means for obtaining a difference between the sound collecting signal of the first microphone and the sound collecting signal of the second microphone when the flip is opened, and sends the subtraction result through the transmitting unit. I am trying.

[0007]

According to the present invention, the first sound collecting microphone is provided on one surface of the flip and the second sound collecting microphone is provided on the other surface. The detection means detects opening and closing of the flip, and when the flip is opened, the two microphones collect sound.

The difference between the sound pickup signals of the two microphones is obtained by the subtracting means. At this time, the background sound having no difference in the sound collection level is removed, and almost only the voice component is formed. Substantially, the subtraction result including only the voice component is transmitted through the transmitting unit.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. As shown in FIG. 1, this embodiment is composed of a transmission system TR and a reception system RV. Transmission system TR
Is a microphone 1, a non-inverting amplifier 4, an adder circuit 6, a non-inverting amplifier 7, a changeover switch 9, an A / D converter 10, and a DSP 1.
1, a transmitter 12, an antenna 14, a microphone 2, and an inverting amplifier 5.

The receiving RV is the antenna 14, the receiving unit 13, D
It is composed of an SP 11, a D / A converter 17, an amplifier 16, and a speaker 15. Each circuit constituting the transmission system TR and the reception system RV is built in the main body 19 to the flip 18 shown in FIGS. In the transmission system TR, the non-inverting amplifier 4 amplifies the sound collection signal output from the microphone 1 in the same phase, and the inverting amplifier 5 amplifies the sound collection signal output from the microphone 2 in the opposite phase. And has substantially the same amplification factor as the non-inverting amplifier 4.

The adder circuit 6 is a circuit for performing analog addition of the sound collection signals output from the non-inverting amplifier 4 and the inverting amplifier 5. The non-inverting amplifier 7 is a circuit that amplifies the sound collection signal output from the adding circuit 6 in the same phase. The change-over switch 9 is a limit switch in this embodiment, and is provided on the side of the main body 19 which is closed by the flip 18, as shown in FIG. As shown in the figure, a convex portion 20 is provided on the side of the flip inner surface 18a facing the installation position of the changeover switch 9, and the convex portion 20 comes into contact with and separates from the changeover switch 9 by the opening / closing operation of the flip 18. ,
The switch 9 is switched between the connection state shown in FIG. 1 (the movable contact c is connected to the contact a) and another connection state (the movable contact c is connected to the contact b).

In the connection state of the changeover switch 9 shown in the figure, the sound collection signal of the microphone 1 is amplified in the same phase by the non-inverting amplifier 4, while the sound collection signal of the microphone 2 is in the opposite phase by the inverting amplifier 5. It is amplified and added by the adder circuit 6. That is, the non-inverting amplifier 4, the inverting amplifier 5, and the adding circuit 6 perform subtraction processing of the sound collection signals of the two microphones 1 and 2.

The output signal of the adder circuit 6 is converted into a digital signal by the A / D conversion section 10 via the non-inverting amplifier 7 and the changeover switch 9, and the DSP 11 and the transmission section 12 perform predetermined modulation and frequency multiplication. Is transmitted from the antenna 14. On the other hand, when the changeover switch 9 is in a connection state different from that shown in the figure, only the sound collection signal of the microphone 2 is sent to the circuits subsequent to the A / D conversion unit 10 through the non-inverting amplifier 8. As shown in FIG. 3, the microphone 1 is provided on the inner surface 18 a side of the flip 18, and the microphone 2 is provided on the outer surface 18 a of the flip 18.
It is provided on the b side.

Both microphones 1 and 2 have a non-directional characteristic or a characteristic close thereto, and therefore, as shown in FIG.
During a call with 8 open, noise emitted from the background will be detected at an equivalent level. The non-inverting amplifier 4 and the inverting amplifier 5 having substantially the same amplification rate are used.

The receiving system RV is a well-known circuit, which receives the received signal input from the antenna 14 into the receiving section 13 and the DSP.
Demodulation and frequency conversion by 11 and D / A conversion unit 17
The analog signal (voice signal) is converted into an analog signal (audio signal), and then the speaker 15 is activated via the amplifier 16. Next, the usage state of the above configuration will be described.

First, when the speaker holds the mobile phone body 19 in his hand and opens the flip 18 and operates a ten-key (not shown) on the body 19 side to make a call, the flip 18 is When opened, the changeover switch 9 enters the connection state shown in FIG. 1, and the sound collection signals of the two microphones are subjected to subtraction processing by the non-inverting amplifier 4, the inverting amplifier 5, and the adding circuit 6.

In this case, as shown in FIG. 3, the microphone 1 is located closer to the speaker's mouth than the microphone 2, and the microphone 2 is located in the shadow of the flip 18, so that the microphone 1 detects it. The voice level is considerably higher than the voice level detected by the microphone 2. On the other hand, it is considered that the background sound reaches from the entire periphery of the mobile phone substantially evenly,
There is almost no difference in the level of the background sound detected by the microphones 1 and 2.

2A and 2B show the levels of the voice and background sound of the microphones 1 and 2 at this time, respectively. Further, FIG. 2C shows a signal waveform after the sound collecting signals of the both microphones 1 and 2 are processed by the adding circuit 6. As shown in this figure, the background sounds detected by both microphones 1 and 2 at the same level are canceled and become almost zero, and almost only the audio component is output. On the other hand, when the flip 18 is closed, the microphone 1 is closed by the main body 19 and the flip 18, and is cut off from the outside world, and the sound collection signal also has a considerably low level.

Therefore, in this case, the changeover switch 9 switches the input system to only the microphone 2 as in the case of the prior art, and transmits using only the sound collection signal from the microphone 2. In the present embodiment, the subtracting means is composed of the non-inverting amplifier 4, the inverting amplifier 5 and the adding circuit 6, but the present invention is not limited to this, and for example, a differential amplifier may be used.

[0020]

As described above, according to the present invention, the two microphones are arranged on both sides of the flip, and the sound collection signals of both microphones are subtracted, so that the background sound detected at the same level is detected. Since the configuration is capable of canceling out, the background sound can be effectively attenuated, and the voice of the speaker can be transmitted with a high S / N ratio.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an example of a mobile phone according to the present invention.

FIG. 2 is a waveform diagram corresponding to FIG. 1, and FIG.
(B) and (C) respectively show the sound collection signals at A, B, and C in FIG. 1 decomposed into a sound component and a background sound component.

FIG. 3 is an external view of a mobile phone according to an embodiment of the present invention with a flip open.

FIG. 4 is an external view of a mobile phone according to an embodiment of the present invention with a flip closed.

[Explanation of symbols]

 1 Microphone 1 2 Microphone 2 4 Non-inverting amplifier 5 Inverting amplifier 6 Adder circuit 9 Changeover switch 12 Transmitter section 18 Flip

Claims (1)

[Claims] 1. In a mobile phone equipped with a flip, a first sound collecting microphone provided on one surface of the flip, a second sound collecting microphone provided on the other surface of the flip, and A detection means for detecting opening and closing; and a subtracting means for obtaining a difference between the sound collection signal of the first microphone and the sound collection signal of the second microphone when the flip is opened, and the subtraction result is sent out through the transmitting section. Mobile phone.