CN1892873A - Motor running noise elimination circuit for portable multimedia player - Google Patents

Abstract

The invention discloses a motor running noise eliminating circuit of a portable multimedia playing device, which comprises: a first sound sensor for sensing and measuring a first sound signal generated when the motor operates and a second sound signal input into the portable multimedia playing device; the second sound sensor is used for sensing and measuring the first sound signal generated when the motor runs; and the noise elimination unit is used for respectively receiving the first sound signal and the second sound signal, performing comparison operation, eliminating the first sound signal and outputting the second sound signal. The invention respectively obtains the input sound signal and the noise source signal through the two sound sensors, eliminates the noise source signal from the input sound signal, eliminates the resonance noise generated by the operation of the motor through a simple and low-cost circuit architecture, and improves the recording quality of the portable multimedia playing device.

Description

Motor running noise elimination circuit for portable multimedia player

technical field

The invention relates to a noise elimination circuit, in particular to a motor operation noise elimination circuit of a portable multimedia player (Portable Multimedia Player, PMP).

Background technique

With the advent of the multimedia era, users can enjoy multimedia entertainment anytime, anywhere through portable multimedia player devices, and portable multimedia player devices store multimedia file data through micro-hard disks. When the micro-hard disk device is in operation, its drive motor generates Vibration causes noise problems. Therefore, in the process of recording sound by the portable multimedia player device, vibration noise is often recorded together, thereby reducing the recording quality of the portable multimedia player device.

Taiwan Patent Publication No. 446258 New Patent discloses an earphone that eliminates environmental noise. It utilizes a microphone placed near the earphone speaker to collect noise in the surrounding environment (such as the ear cavity), and generates an anti-phase (180°) through a circuit. ) sound waves cancel each other out with the original noise sound waves, so that in a specific environment (such as the ear cavity), the pressure balance is maintained to achieve the purpose of eliminating noise.

Taiwan Patent Publication No. 535967 New Patent discloses a mobile phone communication noise canceling device in a car, which includes a sensor installed on the side of a noise source of the vehicle, an analog/digital signal electrically connected to the sensor converter, a digital signal processor electrically connected to the analog/digital converter, a digital/analog signal converter electrically connected to the digital signal processor, and an audio frequency converter electrically connected to the digital/analog signal converter Generating unit, when the audio generating unit receives the analog audio processing signal transmitted by the digital/analog signal converter, it can send out an audio with the same magnitude and opposite phase as the noise of the noise source, in this way, using The audio frequency can interfere with and eliminate the noise emitted by the noise source, so as to improve the receiving quality of the mobile phone during communication.

Although the above-mentioned noise cancellation circuit can improve listening and radio quality, the digital arithmetic unit, compensation circuit or digital signal processor, analog/digital converter and digital/analog converter used in it are not cheap circuit components. Therefore, the cost of the noise canceling circuit will increase.

Therefore, how to provide a low-cost portable multimedia player device motor running noise elimination circuit to improve the recording quality of the portable multimedia player device has become one of the problems to be solved by researchers.

Contents of the invention

In view of the above problems, the main purpose of the present invention is to provide a motor running noise elimination circuit for a portable multimedia player, which can eliminate the motor running noise in the recording process by obtaining the sound signal of the motor running, so as to avoid the noise in the recorded sound. The motor running noise is included, and the recording quality of the portable multimedia playback device is improved.

To achieve the above object, the invention provides a motor running noise elimination circuit of a portable multimedia player, comprising:

A first sound sensor, inductively measuring a first sound signal generated when the motor is running and a second sound signal input to the portable multimedia playback device, and the first sound signal is combined with the second sound signal when recording. in the sound signal;

a second sound sensor for inductively measuring the first sound signal generated when the motor is running; and

A noise elimination unit, respectively receiving the first sound signal and the second sound signal sensed and measured by the first sound sensor and the second sound sensor, and performing a comparison operation, eliminating the first sound signal and outputting the second sound signal.

The motor operation noise elimination circuit of the portable multimedia player is characterized in that it further includes a sound recording unit for recording the second sound signal output by the noise elimination unit.

The motor operation noise elimination circuit of the portable multimedia player device of the present invention obtains the input sound signal and the noise source signal respectively through at least two sound sensors, and then eliminates the noise source signal in the input sound signal, so, through simple and low The low-cost circuit structure eliminates the resonance noise generated by the operation of the motor, and improves the recording quality of the portable multimedia playback device.

Description of drawings

Fig. 1 is the system block diagram of noise elimination of the present invention;

2A and 2B are circuit diagrams of the differential amplifier of the present invention; and

3 is a schematic cross-sectional view of the position of the sound sensor of the portable multimedia player device of the present invention.

Among them, reference signs:

10 first sound sensor

11 Second sound sensor

12 noise canceling unit

13 sound recording unit

20 motor

21 First sound signal

22 second sound signal

30 case

30a sound hole

Iss current source

Q1 Transistor

Q2 Transistor

Q3 metal oxide semiconductor field effect transistor

Q4 metal oxide semiconductor field effect transistor

R1～R3 resistance

V1 input terminal

V2 input

Vo output terminal

VCC positive voltage source

VEE negative voltage source

Detailed ways

As shown in FIG. 1 , it is a block diagram of the noise elimination system of the present invention, including: a first sound sensor 10 , a second sound sensor 11 , a noise elimination unit 12 and a motor 20 .

The first sound sensor 10 is arranged in the portable multimedia player device, and a sound receiving hole is provided on the shell of the portable multimedia player device to provide the first sound signal 21 and the external environment produced by the first sound sensor 10 inductively measuring the motor 20 running. The second sound signal 22 of input (such as music or speech etc.), first sound signal 21 is combined in the second sound signal 22 of external environment input during recording, and wherein first sound sensor 10 can be made of capacitive microphone, moving coil microphone or silicon microphone.

The second sound sensor 11 is arranged in the portable multimedia player, and is used for inductively measuring the vibration noise (i.e. the first sound signal 21) produced when the motor 20 runs, wherein the second sound sensor 11 can be composed of a capacitive microphone, a moving coil microphone or silicon microphone.

The noise canceling unit 12 is connected with the first sound sensor 10 and the second sound sensor 11 respectively, so as to receive the first sound signal 21 and the second sound signal 22 respectively, and sense the first sound sensor 10 and the second sound sensor 11 The measured first sound signal 21 is compared with the second sound signal 22 to eliminate the first sound signal 21 and output the second sound signal 22, and the noise elimination unit 12 can be configured by a differential amplifier (Differential Amplifier) It has two input terminals and an output terminal, the first acoustic sensor 10 is connected to the inverting input terminal of the differential amplifier, and the second acoustic sensor 11 is connected to the non-inverting input terminal of the differential amplifier.

The sound recording unit 13 is connected with the noise canceling unit 12 for recording the second sound signal 22 outputted by the noise canceling unit 12, wherein the sound recording unit 13 can be composed of a micro hard disk or a flash memory.

The motor 20 is arranged in the portable multimedia player and is used to provide the power required for the operation of the storage medium (such as a micro hard disk).

2A is a schematic circuit diagram of a differential amplifier, including: a resistor R1 , a resistor R2 , a resistor R3 , a transistor Q1 , a transistor Q2 and a current source Iss.

First, the first sound signal 21 and the second sound signal 22 sensed and measured by the first sound sensor 10 are input to the input terminal V1, and the input end V1 is connected to the base of the transistor Q1. Next, the second sound sensor 11 The first sound signal 21 sensed and measured is input to the input terminal V2, and the input terminal V2 is connected to the base of the transistor Q2, the collector of the transistor Q1 is connected to one end of the resistor R1, and the other end of the resistor R1 is connected to a positive voltage source VCC, the emitter of the transistor Q1 is connected to one end of the current source Iss, and the other end of the current source Iss is connected to the negative voltage source, the resistor R3 is connected in parallel with the current source Iss, the collector of the transistor Q2 is connected to one end of the resistor R2, and The other end of the resistor R2 is connected to the positive voltage source VCC, the emitter of the transistor Q2 is connected to one end of the current source Iss, and the other end of the current source Iss is connected to the negative voltage source.

After the comparison operation of the differential amplifier, the output terminal Vo amplifies and outputs the second sound signal 22, and the output terminal Vo is connected with the sound recording unit 13 to record the second sound signal 22. In addition, as shown in Figure 2B, it is the present invention The circuit diagram of another embodiment of the differential amplifier of FIG. 2A is different from that in FIG. 2A in that the transistor Q1 and the transistor Q2 are replaced by a metal oxide semiconductor field effect transistor Q3 and a metal oxide semiconductor field effect transistor Q4, and the rest are the same , so I won’t go into details.

As shown in Figure 2, it is a schematic cross-sectional view of the position of the sound sensor of the present invention, wherein the first sound sensor 10 is adjacent to the second sound sensor 11, and a sound receiving hole 30a is opened in a place of the casing 30 for providing the first sound sensor 11. A sound sensor 10 senses and measures the first sound signal 21 input from the external environment. During the recording process, the motor 20 runs and vibrates to cause the casing 30 to resonate, thereby generating the first sound signal 21. The second sound sensor 11 is used to The second sound signal 21 is sensed and measured, and no sound receiving hole 30 a is opened at the position of the second sound sensor 11 , so as to completely sense and measure the first sound signal 21 resonated by the motor 20 and the casing 30 .

Through the motor operation noise elimination circuit of this portable multimedia player, the input sound signal and the noise source signal are obtained respectively through at least two sound sensors, and then the noise source signal is eliminated from the input sound signal, so that, through simple and low The low-cost circuit structure eliminates the resonance noise generated by the operation of the motor, and improves the recording quality of the portable multimedia player.

Certainly, the present invention also can have other multiple embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding Changes and deformations should belong to the scope of protection of the appended claims of the present invention.

Claims (11)

1. A motor running noise elimination circuit for a portable multimedia player, characterized in that it comprises: A first sound sensor, inductively measuring a first sound signal generated when the motor is running and a second sound signal input to the portable multimedia playback device, and the first sound signal is combined with the second sound signal when recording. in the sound signal; a second sound sensor for inductively measuring the first sound signal generated when the motor is running; and A noise elimination unit, respectively receiving the first sound signal and the second sound signal sensed and measured by the first sound sensor and the second sound sensor, and performing a comparison operation, eliminating the first sound signal and outputting the second sound signal. 2. The motor running noise cancellation circuit for a portable multimedia player according to claim 1, wherein the first sound sensor is a condenser microphone. 3. The motor running noise cancellation circuit for a portable multimedia player according to claim 1, wherein the first sound sensor is a dynamic microphone. 4. The motor running noise cancellation circuit for a portable multimedia player according to claim 1, wherein the first sound sensor is a silicon crystal microphone. 5. The motor running noise cancellation circuit for a portable multimedia player according to claim 1, wherein the second sound sensor is a condenser microphone. 6. The motor running noise cancellation circuit for a portable multimedia player according to claim 1, wherein the second sound sensor is a dynamic microphone. 7. The motor running noise cancellation circuit for a portable multimedia player according to claim 1, wherein the second sound sensor is a silicon crystal microphone. 8. The motor running noise elimination circuit of a portable multimedia player according to claim 1, wherein the noise elimination unit is a differential amplifier. 9. The motor running noise elimination circuit of a portable multimedia player according to claim 8, wherein the first sound signal sensor is connected to the inverting input terminal of the differential amplifier. 10. The motor running noise elimination circuit for a portable multimedia player according to claim 8, wherein the second sound signal sensor is connected to the phase-stop input terminal of the differential amplifier. 11. The motor running noise elimination circuit of a portable multimedia player according to claim 1, further comprising a sound recording unit for recording the second sound signal output by the noise elimination unit.

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