KR19980020180A - Automotive hand-free device with echo protection - Google Patents

Abstract

In the present invention, commercially available digital mobile phone technologies include a time division method (TDMA) and a code division method (CDMA). A slight time delay occurs in the digital process of a voice signal. Echo phenomenon in which the voice of the other party heard through the handfree microphone is inevitably generated. According to the present invention, the gain of the handfree microphone amplification stage is increased according to the size of the sound of the handfree speaker that the other party speaks to solve this problem. This is a hand-free device that automatically reduces and adjusts to minimize the effect of the sound of the hand-free speaker on the head-free microphone and to the other party, and the echo of the microphone amplifier stage decreases inversely with the loudness of the speaker. It is possible to minimize the When you listen to when you speak and the general form that the other party hears in this way, even if the hands-free device is provided, you can make a phone call without any inconvenience. Also, the gain of the microphone is adjusted by referring to the signal of the hands-free speaker only, so there is no influence of other sounds in the car (radio, dialogue).

That is, even when talking on the handfree device of the analog mobile phone, the other party's sound is reversely output to the speaker of the other party through the handfree microphone. Digital mobile phones are echoed by the time difference between speaking and listening due to time delays of about tens of milliseconds. Currently, it is difficult to fundamentally eliminate this phenomenon. The use of seismic and suction materials to block speaker vibrations from being transmitted to the microphone is solved. However, since the hand-free device has a high output of the speaker, it is not possible to fundamentally block the input of the microphone by this solution. Therefore, the solution of the microphone and the speaker considering the propagation path of the sound wave is solved by this method. Since it does not basically solve the echo phenomenon, the present invention basically reduces or decreases the amplification rate of the microphone according to the loudness of the speaker through the present invention so that the sound of the speaker is transmitted to the other party through the mobile telephone network. It is possible to provide a hand free device.

Description

Automotive hand-free device with echo protection

1 is a configuration diagram of a vehicle hand-free device to which the echo prevention function of the present invention is applied.

2 is a circuit diagram of a vehicle hand-free device to which the echo prevention function of the present invention is applied.

Explanation of symbols on the main parts of the drawings

1: cell phone 2: antenna

3: stand 4: terminal for charging mobile phones

5: hand-free detection switch 6: battery charge control circuit

7: Microphone, speaker amplification circuit 8: Hand-free speaker

9: hand-free microphone 10: car power connector

11: cell phone socket 12: codec circuit

13: Speaker amplifier 14: Speaker

15: Speaker level detection circuit 16: Amplification gain adjustment circuit

17: microphone amplifier 18: microphone

19: echo adjustment switch 20: hand-free detection switch

[Field of Invention]

The present invention relates to a hand-free device using a mobile phone in a vehicle so that it does not interfere with driving. When a general hand-free device is used due to a time delay effect inevitably caused by the digitalization of mobile phone technology, There is an echo of his voice echoed back to the normal form difficult to call, which is a hand-free device that can solve this echo phenomenon.

In other words, currently commercially available digital mobile phones have a time division method (TDMA) and a code division method (CDMA). There is a slight time delay in the digital process of the signal. Echo phenomenon in which the voice is heard back to the other party by the hand-free microphone is inevitably generated. The present invention allows the other party to automatically reduce and reduce the gain of the hand-free microphone amplifier according to the loudness of the other party. It essentially blocks the echo effect.

[Background of invention]

As the mobile phone is digitalized, a process of encoding a voice signal is required, and thus a time delay occurs. In particular, the time encoding method has a larger time delay than the code encoding method. When talking on a digital mobile phone that has such a time delay, the other party experiences an echo in which the sound of the mobile phone speaker returns to itself through the mobile phone microphone with a slight time delay while talking. Even in the case of a mobile phone, it occurs minutely, and in a hand free device, the call itself is difficult enough.

As a result, digital hands-free devices have a lot of problems in dissemination, such as the installation of microphones and speakers in the car, unlike the analog method. Despite the ban and the need for hands-free calls, it is difficult to recommend.

Digitalization of mobile phone technology is inevitable for reasons such as battery current consumption, call quality, increased capacity, and providing various data communications.These digital mobile phones are convenient to use while walking, but the hand-free function used while driving in vehicles is also safe. It is important for. Such hand-free device should provide convenience and good call quality from the user's point of view. However, the echo of the other party during the call due to the inevitable time delay in digitalization hinders the smooth call. The solution is difficult to solve by the hand-free technology through the present invention.

[Purpose of invention]

An object of the present invention is to improve the call quality by eliminating the echo phenomenon, which is a time delay effect due to digitalization, especially when using a handfree device for a vehicle, which occurs when making a call using a digital mobile phone, and improves the gain of the handfree microphone stage. It is to provide a hand-free device that minimizes the echo effect transmitted to the speaker of the other party through the microphone when the other party talks by automatically adjusting to be inversely proportional to the output of the hand-free speaker.

That is, even when talking on the handfree device of the analog mobile phone, the other party's sound is reversely output to the speaker of the other party through the handfree microphone. Digital mobile phones have echo delays of about tens of milliseconds and sound like echoes due to the time difference between speaking and listening. These phenomena are difficult to eliminate fundamentally. The use of seismic and suction materials to block speaker vibrations from being transmitted to the microphone is solved. However, since the hand-free device has a high output of the speaker, it is not possible to fundamentally block the input of the microphone by this solution. Therefore, the solution of the microphone and the speaker considering the propagation path of the sound wave is solved by this method. And it does not basically solve the echo phenomenon, through the present invention by reducing or blocking the amplification rate of the microphone inversely in accordance with the loudness of the speaker to reduce the speaker's sound is basically transmitted to the other party through the mobile telephone network It is possible to provide a hand free device.

[Summary of invention]

In the present invention, commercially available digital mobile phone technologies include a time division method (TDMA) and a code division method (CDMA). Some time delay occurs in the digital process of a voice signal. Echo phenomenon in which the voice of the other party heard through the handfree microphone is inevitably occurred to the other party, and the present invention provides an advantage of amplifying the handfree microphone according to the loudness of the handfree speaker speaking to solve the problem. This is a hand-free device that automatically reduces and adjusts the sound of the hand-free speaker to minimize the effect of the hand-free microphone coming back to the other party, and the gain of the microphone amplifier decreases inversely with the loudness of the speaker. It is possible to minimize the phenomenon, which is why Can be on the phone without listening to this type of hands-free devices offer the same comfort even when you Whenever you see a common currency the form of listening to the other party. Also, the gain of the microphone is adjusted by referring to the signal of the hands-free speaker only, so there is no influence of other sounds in the car (radio, dialogue).

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Detailed description of the invention

The present invention eliminates the echo effect, which is a time delay effect caused by digital coding, especially when using a mobile handfree device for a digital mobile phone, and improves the call quality. The present invention relates to a hand-free device capable of minimizing an echo effect transmitted back to a speaker of a counterpart when a counterpart talks by automatically adjusting the output to be inversely proportional to the output of the pre-speaker stage. It will be described in detail as follows.

A schematic block diagram of a handfree device for a vehicle to which an echo prevention function is provided in accordance with the present invention is shown in FIG. The hand free device to which the echo prevention function of the present invention is provided has a charging circuit and a mobile phone charging terminal 4 and a hand free switch 5 when the mobile phone 1 with the antenna 2 is placed on the holder 3. Handfree-related circuits are connected, and microphone / speaker amplification and control circuits with built-in microphone auto gain adjustment circuits are connected inversely to the output of the handfree speaker 8 to minimize echoes. By adjusting the gain of the microphone 9, it is configured to be insensitive to the microphone when the sound of the other party transmitted through the telephone line is loud, and to increase the microphone gain when the sound of the other party is small, and to be sensitive to a car power supply such as a cigar jack. The driving power is supplied by the connection device 10. If necessary, a separate echo control switch can be set to change the microphone amplification adjustment rate. In this configuration, even if the microphone and speaker positions are not optimized, the echo phenomenon occurring in the other party's phone is artificially extremely weak, thereby improving call quality.

2 is a detailed circuit diagram for implementing the present invention, when the hand-free detection switch 20 is set in the hand-free state through the external socket 11 of the mobile phone 1, the socket 11 has a digital PCM speaker output and a microphone. The digital PCM output is amplified by the speaker amplifier 13 through a CODEC circuit 12 which processes an input and is interchanged with an analog signal to drive an external speaker 14 for hand-free, and a hand-free microphone 18. The audio signal is input to the CODEC circuit 12 via the microphone amplifier amplifier 17 and converted into a digital PCM signal. At this time, the amplification gain of the microphone amplification amplifier 17 is differentially adjusted by the amplification gain adjusting circuit 16 at the amplification ratio set according to the voltage level of the speaker signal level sensing circuit 15. If the voltage level is high, the amplification ratio is decreased or zero. If the voltage level is low, the other party's conversation is stopped, so that the amplification rate is increased.The range of the amplification rate can be changed by the echo adjustment switch 19. Make good adjustments. The amplification gain adjusting circuit 16 can be realized simply by adjusting the resistance value or the corresponding input reference voltage value corresponding to the speaker signal to determine the amplification factor of the amplifier stage. The echo phenomenon that occurs in digital mobile phones is caused by the time delay that accompanies digitalization. Even though a mobile phone is small, this problem occurs due to internal resonance and case vibration. However, when using a hand-free speaker, it is not possible to fundamentally prevent the microphone from being re-entered, and the only alternative is to reduce the microphone gain when the other party talks so that speaker sound is not input.

As described above, the digitalization of mobile phone technology is inevitable due to battery current consumption, call quality, increased capacity, and providing various data communication.These digital mobile phones are convenient for use while walking, but are hand-free for use while driving in a vehicle. In addition, it is important for safe driving, and these hand-free devices should provide convenience and quality call quality from the user's point of view. This must be removed essentially, but the present solution has been proposed as described above through the present invention as it is difficult with the current hand-free technology.

As a result, the digital hand-free device known to date has a lot of problems in dissemination, such as paying close attention to the installation position of the microphone and speaker in the car, unlike the analog method. Despite the prohibition of the use of mobile phones and the need to make calls in a hands-free manner, the generalization and convenience of the upcoming digital personal communication (PCS) is solved by solving the limitation of use due to the problem that the call quality was poor due to the echo phenomenon. It is expected to contribute to.

Although the invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that modifications and variations can be made within the spirit and scope of the invention, and such modifications or changes should be limited by the appended claims.

Claims (3)

In the hand-free device for a mobile phone, when the hand-free detection switch 20 is set in the hand-free state through the external socket 11 of the mobile phone 1, the socket 11 processes the digital PCM speaker output and the microphone input. The digital PCM output is amplified through the speaker amplifier 13 to drive the external speaker 14 for hand-free through the CODEC circuit 12 converting the signal to and from the analog signal. The amplification gain is input to the CODEC circuit 12 through the amplification amplifier 17 and converted into a digital PCM signal. The amplification gain of the microphone amplification amplifier 17 amplifies the amplification ratio according to the voltage level of the speaker signal level detection circuit 15. If the voltage level is high, the amplification rate is lowered or set to zero, and if the voltage level is low, the conversation of the other party is stopped. Therefore, the amplification rate is increased. The variation range of the echo protection, characterized in that the configuration allows the echo falls microphone sensitivity of the call to be able to change to the echo adjustment switch 19, but the sensitivity is adjustable give good vehicle hands-free device. The amplification gain of the microphone amplifying amplifier 17 is also used in the cellular phone 1, which is configured so that an analog signal is inputted and outputted by directly connecting an internal speaker and a microphone to a signal output through the external socket 11 of the cellular phone 1. Differentially adjusts the amplification rate with the amplification gain adjusting circuit 16 according to the voltage level of the speaker signal level sensing circuit 15. If the voltage level is high, the amplification rate is lowered or set to zero. It is configured to increase the amplification rate, so that the amplification rate fluctuation range can be changed by the echo adjustment switch 19 so that when the microphone sensitivity drops during a call, there is an echo, but the sensitivity is configured to adjust the sensitivity well. Handfree device for a vehicle to which a function is given. According to claim 2, if the external socket (11) of the mobile phone does not use a separate hand-free setting circuit to put on the cradle, the sound of the speaker inside the mobile phone (1), but the separate device by the hand-free detection switch (5) Low (lead switch or relay) A simple hand-free device configured to sound external speakers by operating an external speaker drive circuit.