TWI702855B - Active noise reduction device with sound filter and earphone - Google Patents

Abstract

An active noise reduction device with a sound filter, comprising: a housing including first and second channels, the channel length of the first channel is greater than the channel length of the second channel; an active noise reduction unit, including : An external microphone is arranged outside the housing to detect an environmental noise, wherein the position of the external microphone corresponds to the position of the first outer end of the first channel; a speaker is arranged on the second channel of the second channel The external end is used for outputting the inverted signal of the environmental noise; and a noise reduction processor electrically coupled to the external microphone and the speaker; and a sound filter arranged in the first channel.

Description

Active noise reduction device with sound filter and earphone

The present invention relates to a noise reduction device, and particularly relates to an active noise reduction device, earmuff earphones and in-ear earphones.

The most common traditional noise suppression technology is mostly achieved by using various sound-absorbing materials to passively absorb the energy of noise. However, at low frequencies, the wavelength of sound is much larger than the thickness of general sound-absorbing materials. For example, sound with a frequency of 100 Hz has a wavelength of about 3 to 4 meters at room temperature and sea level. Therefore, unless you use very heavy sound-absorbing equipment It can effectively block the transmission of low-frequency sound, and for general applications, this passive noise cancellation technology is not ideal for low-frequency noise isolation. Therefore, in practical applications, passive noise cancellation methods often have to strike a balance between the effective elimination of low-frequency noise and the problem of sound-absorbing equipment that may occupy space, bulky and expensive.

In order to effectively overcome the aforementioned problems, an Active Noise Control (ANC) theory that uses an external sound source to eliminate noise has caused extensive and in-depth research and development over the years. The basic principle of the active noise control system is mainly to use the principle of waveform synthesis to generate an anti-noise sound wave with the same waveform as the original noise, the same size, and a phase difference of 180 degrees, so that it can destructively interfere with the original noise to achieve the noise volume The purpose of reduction. Please refer to Figure 1, which shows the original noise waveform L1, the anti-noise waveform L2, and the residual noise waveform L3 after the original noise and the anti-noise waveform are superimposed.

Taiwan Patent Certificate No. I609363 discloses an active noise reduction correction system and speaker device. Please refer to FIG. 2. The prior art of the patent document shows the structure of an active noise reduction system. The microphone 90 is used to receive external environmental noise. The noise source is adjusted by the active filter 92 to obtain an appropriate frequency response, which includes appropriate amplitude and phase response, so that the headphone speaker 94 outputs an inverted signal that is almost the original noise source. Horn hair The out-of-phase noise can be added to the original noise in the earphone earmuff 96 of the listener 8. The result of this cancellation can greatly reduce the external noise heard by the listener 8. It is the principle of general active noise reduction headphones.

However, the main noise reduction range of general active noise reduction headphones is 50~2KHz in the low frequency range, and the high frequency noise reduction effect is not good. Furthermore, even if the ambient sound can be heard, the previous technology has not mentioned that only the sound of a certain frequency band is heard. Therefore, in a noisy environment, it is necessary to filter out most of the noise, and expect to hear the speech sound, even the sound of a specific frequency band. , Generally need to be processed through digital signals. Generally speaking, the circuit design for blasting sound protection is processed by high-speed digital electronic signals, which is costly.

Therefore, there is a need to provide an active noise reduction device with a sound filter to solve the aforementioned problems.

An object of the present invention is to provide an active noise reduction device with a sound filter, which combines an active noise reduction unit and a sound filter.

According to the above objective, the present invention provides an active noise reduction device with a sound filter, comprising: a housing including first and second channels, the channel length of the first channel is greater than the channel length of the second channel; An active noise reduction unit, including: an external microphone arranged outside the housing for detecting an environmental noise, wherein the detection position of the external microphone is close to the position of the first outer end of the first channel; a speaker , Arranged at the second outer end of the second channel for outputting an inverted signal of the environmental noise; and a noise reduction processor electrically coupled to the external microphone and the speaker; and a sound filter arranged at The first channel.

The active noise reduction device with a sound filter of the present invention combines an active noise reduction unit (which includes an external microphone, a speaker, and a noise reduction processor) and the sound filter to form a band-pass filter to enable a specific frequency domain The sound can enter the ear canal of the listener through the shell. The active noise reduction unit makes the noise from the first channel of the housing to the ear canal to reduce the noise intensity evenly with the frequency below 1KHz; and the sound filter makes the noise of the first channel through the housing The noise to the ear canal increases as the frequency increases above the frequency of 1KHz.

1‧‧‧Active noise reduction device

1’‧‧‧Active noise reduction device

10‧‧‧Shell

10’‧‧‧Shell

101‧‧‧The first channel

101’‧‧‧The first channel

101a‧‧‧First outer passage

101b‧‧‧The first inner passage

101c‧‧‧Second inner passage

1011‧‧‧First inner end

1012‧‧‧First outer end

1013‧‧‧Tube shape of low-pass filter

1014‧‧‧Cavity

102‧‧‧Second channel

1021‧‧‧Second inner end

1022‧‧‧Second outer end

1023‧‧‧side

1024‧‧‧side

111‧‧‧External microphone

112‧‧‧Speaker

113‧‧‧Noise reduction processor

114‧‧‧Internal microphone

115‧‧‧Audio signal components

12‧‧‧Sound filter

2‧‧‧Earphone

21‧‧‧Earmuffs

3‧‧‧In-ear headphones

31‧‧‧Headphone shell

312‧‧‧outer end

32‧‧‧Protrusion

33‧‧‧Channel

8‧‧‧Recipient

81‧‧‧Ear Canal

90‧‧‧Microphone

92‧‧‧Active filter

94‧‧‧Speaker

96‧‧‧Earmuffs

8‧‧‧Recipient

81‧‧‧Ear Canal

L1‧‧‧Original noise waveform

L2‧‧‧Anti-noise waveform

L3‧‧‧Residual noise waveform

LL‧‧‧Cavity length

S1‧‧‧First pipe diameter

S2‧‧‧Second pipe diameter

S3‧‧‧The third pipe diameter

Figure 1 is a comparison diagram of the difference between the original noise waveform, the anti-noise waveform and the residual noise waveform of the prior art.

Figure 2 is a schematic diagram of the structure of a conventional active noise reduction system.

3 is a schematic diagram of the structure of an active noise reduction device with a sound filter according to the first embodiment of the present invention.

4 is a schematic cross-sectional view of the tubular shape of the sound filter and low-pass filter of the present invention.

Fig. 5 is a schematic cross-sectional view of the tubular shape of the low-pass filter of the present invention.

6 is a schematic structural diagram of an active noise reduction device with a sound filter according to another embodiment of the present invention.

FIG. 7 is a schematic diagram of the structure of an over-ear earphone according to an embodiment of the present invention.

8 is a schematic diagram of the structure of an in-ear earphone according to an embodiment of the present invention.

9 is a schematic diagram of the structure of an active noise reduction device with a sound filter according to a second embodiment of the present invention.

In order to make the above-mentioned objectives, features and characteristics of the present invention more obvious and understandable, the relevant embodiments of the present invention are described in detail below in conjunction with the drawings.

FIG. 3 is a schematic diagram of the structure of the active noise reduction device 1 with a sound filter according to the first embodiment of the present invention. The active noise reduction device 1 includes: a housing 10, an active noise reduction unit (which includes an external microphone 111, a speaker 112 and a noise reduction processor 113 ), and a sound filter 12. The housing 10 includes first and second channels 101 and 102. The channel length between the first inner end 1011 and the first outer end 1012 of the first channel 101 is greater than the second inner end 1021 and the second channel 102 of the second channel 102. The length of the channel between the second outer ends 1022. The first inner end 1011 and the second inner end 1021 refer to one end of the channel close to the ear canal 81, and the first outer end 1012 and the second outer end 1022 refer to the other end of the channel away from the ear canal 81. In this embodiment, the first channel 101 is located in the second channel 102 one side 1023. The material of the shell 10 can be selected from silicone, thermoplastic elastomer (TPE), thermoplastic rubber elastomer (Thermoplastic Rubber, TPR), thermoplastic vulcanizate (Thermoplastic Vulcanizate, TPV), thermoplastic polyurethane resin (Thermoplastic Polyurethane, TPU) , Thermoplastic Polyether Ester Elastomer (TPEE), or a mixture of them.

The active noise reduction unit includes: an external microphone 111, a speaker 112, and a noise reduction processor 113. The external microphone 111 is disposed outside the housing 10 to detect an environmental noise. The detection position of the external microphone 111 is close to the position of the first outer end 1012, for example, the position of the external microphone 111 is close to the first outer end 1012. The location of an outer end 1012. The speaker 112 is disposed at the second outer end 1021 for outputting an inverted signal of the environmental noise, wherein the second outer end 1021 is a closed end. The noise reduction processor 113 is electrically coupled to the external microphone 111 and the speaker 112 for inverting and transmitting the environmental noise detected by the external microphone 111 to the speaker 112, and the speaker 112 passes through the second channel 102 and output the inverted signal of the environmental noise, which can reduce the environmental noise transmitted to the ear canal 81 of the listener 8 through the first channel 101.

For example, since the channel length of the first channel 101 is greater than the channel length of the second channel 102, and the position of the external microphone 111 is close to the position of the first outer end 1012, the noise reduction processor 113 can be based on the speaker 112 The output of the inverted signal of the environmental noise passes through the second channel 102 and the time when the environmental noise passes through the first channel 101 to adjust the signal and phase so that the environmental noise and its inverted signal are in the first channel. The first inner end 1011 of the channel 101 and the second inner end 1021 of the second channel 102 achieve a better superposition effect, thereby obtaining a better noise reduction effect.

The sound filter 12 is arranged in the first channel 101. Please refer to FIGS. 4 and 5, the first channel 101 further includes a low-pass filter tubular shape 1013 having a cavity 1014 for accommodating the sound filter 12. The tubular shape 1013 of the low-pass filter further has first, second and third pipe diameters S1, S2, S3, and cavity length LL, wherein the second tube diameter S2 is greater than the first and third tube diameters S1 and S3, and the cavity length LL and the second tube diameter S2 form the cavity 1014. The tubular shape 1013 of the low-pass filter can enhance the effect of the low-pass filter.

For example, the sound filter 12 contains a thin film that can attenuate the intensity of the incoming sound. The sound filter 12 can significantly improve the attenuation effect of high-frequency noise above 1 KHz from the first channel 101 of the housing 10 to the ear canal 81 of the listener 8.

Therefore, the active noise reduction device 1 with a sound filter of the present invention combines the active noise reduction unit (which includes the external microphone 111, the speaker 112, and the noise reduction processor 113) and the sound filter 12 to form a band-pass filter (Band Pass Filter), which is used to enable sound of a specific frequency domain to enter the ear canal 81 of the listener 8 through the housing. The active noise reduction unit makes the noise from the first channel 101 of the housing 10 to the ear canal 81 to reduce the noise intensity evenly with the frequency below 1KHz; and the sound filter 12 allows the noise to pass through the housing 10 For the noise from the first channel 101 to the ear canal 81, the noise reduction effect increases as the frequency increases above 1KHz.

In particular, the active noise reduction unit can have a lower noise reduction effect in the 80~520Hz part, allowing the main frequency of human speech to pass. If combined with a filter, the noise above 1KHz can be greatly reduced, and the equal loudness curve ( Such as ISO 226) designed to highlight the loudness of human speech.

The active noise reduction device with a sound filter of the present invention combines the active noise reduction unit and the sound filter to increase the freedom of adjusting the noise reduction curve and reduce the development cost of active noise reduction processing software and hardware. For general active noise reduction units, the low-frequency domain noise reduction is easy, but the high-frequency domain noise reduction is difficult. The general sound filter has a better high-frequency filtering effect, so the combination of the two can form a band-pass filter, which can let speech or alarm sounds pass in a noisy environment.

Please refer to FIG. 6, in another embodiment, the active noise reduction unit 11 further includes: an internal microphone 114 located in the first inner end 1011 of the first channel 101 and the second inner end of the second channel 102 Near the exit area outside the end 1021. The internal microphone 114 is a microphone for receiving error signals, and the internal microphone 114 The noise reduction processor 113 is electrically coupled to transmit error signals to the noise reduction processor 113; the external microphone 111 is a microphone that receives the reference signal, and the external microphone 111 is also used to transmit the reference signal to the noise reduction processor 113. Noise processor 113. For example, using the architecture of this active noise reduction technology, the external microphone 111 receives the reference signal, and then the internal microphone 114 receives the reduced environmental noise (error signal). The error signal is fed back to the noise reduction processor 113, and the noise reduction The processor 113 can automatically adjust the parameters of a digital filter (such as a digital finite impulse response filter, Digital FIR Filter), and the speaker 112 has a built-in amplifier, such as a Class-D Amplifier, which can receive the noise reduction processor The signal of 113 is converted into an audio signal, and the purpose is to suppress the noise transmitted to the ear canal 81 to a minimum.

In another embodiment, the active noise reduction unit 11 further includes: an audio signal element 115. The sound signal component 115 (such as a wireless signal receiver) is electrically coupled to the noise reduction processor 113 to receive an external sound signal (music, speech sound, etc.) and provide it to the noise reduction processor 113.

FIG. 7 is a schematic diagram of the structure of an over-ear earphone according to an embodiment of the present invention. The over-ear earphone 2 includes an earmuff 21 and the active noise reduction device 1 with a sound filter of the present invention. The active noise reduction device 1 with a sound filter can be installed in the over-ear earphone 2 Inside the earmuffs 21.

8 is a schematic diagram of the structure of an in-ear earphone according to an embodiment of the present invention. The in-ear earphone 3 includes: an earphone housing 31 and the active noise reduction device 1 with a sound filter of the present invention, and the active noise reduction device 1 with a sound filter can be installed in the earphone housing 31 Inside. The housing of the active noise reduction device 1 with a sound filter and the earphone housing 31 can be integrally formed with the same material, for example. The housing of the active noise reduction device 1 with a sound filter and the material of the earphone housing 31 can be selected from silicone, thermoplastic elastomer (TPE), thermoplastic rubber elastomer (Thermoplastic Rubber, TPR), Thermoplastic Vulcanizate (TPV), Thermoplastic Polyurethane (TPU), Thermoplastic Polyether Ester Elastomer (TPEE), or a mixture thereof. The earphone 3 further includes A protrusion 32 is located at an outer end 312 of the earphone housing 31. After the earphone 3 is inserted into the ear canal of the listener, the listener can easily grasp the protrusion 32 and pull out the earphone 3 easily. The protrusion 32 has a channel 33 for allowing sound to enter the earphone housing 31.

Fig. 9 is a schematic diagram of the structure of an active noise reduction device 1'with a sound filter according to the second embodiment of the present invention. The active noise reduction device 1'with a sound filter of the second embodiment is substantially similar to the active noise reduction device 1 with a sound filter of the first embodiment, and similar components are marked with similar numbers. The main difference between the two is: the first channel 101' of the housing 10' of the active noise reduction device 1'with a sound filter includes a first outer channel 101a, a first inner channel 101b, and a second inner channel 101c , The first outer channel 101a communicates with the first inner channel 101b and the second inner channel 101c at the same time, and the first inner channel 101b and the second inner channel 101c are located on both sides 1023, 1024 of the second channel 102, wherein The sound filter 12 is located in the outer channel 101 a of the first channel 101.

Similarly, the active noise reduction device with a sound filter of the present invention combines the active noise reduction unit (which includes an external microphone 111, a speaker 112, and a noise reduction processor 113) and the sound filter 12 to form a band-pass filter (Band Pass Filter), which is used to enable sound of a specific frequency domain to enter the ear canal 81 of the listener 8 through the housing. The active noise reduction unit makes the noise from the first channel 101' of the housing 10 to the ear canal 81 to reduce the noise intensity evenly with the frequency below 1KHz; and the sound filter 12 allows the noise to pass through the housing The noise from the first channel 101' to the ear canal 81 of 10 has an effect of reducing noise as the frequency increases above 1KHz.

The active noise reduction device with a sound filter of the present invention combines the active noise reduction unit and the sound filter to increase the freedom of adjusting the noise reduction curve and reduce the development cost of active noise reduction processing software and hardware. For general active noise reduction units, the low-frequency domain noise reduction is easy, but the high-frequency domain noise reduction is difficult. The general sound filter has a better high-frequency filtering effect, so the combination of the two can form a band-pass filter, which can let speech or alarm sounds pass in a noisy environment.

Active noise reduction device with sound filter according to the second embodiment of the present invention Set 1'can also be applied to the above-mentioned over-ear headphones or in-ear headphones.

To sum up, it only describes the preferred implementations or examples of the technical means adopted by the present invention to solve the problems, and is not used to limit the scope of implementation of the patent of the present invention. That is to say, all the equivalent changes and modifications made in accordance with the scope of the patent application of the present invention or made in accordance with the scope of the patent of the present invention are covered by the scope of the present patent.

1‧‧‧Active noise reduction device

10‧‧‧Shell

101‧‧‧The first channel

1011‧‧‧First inner end

1012‧‧‧First outer end

102‧‧‧Second channel

1021‧‧‧Second inner end

1022‧‧‧Second outer end

1023‧‧‧side

111‧‧‧External microphone

112‧‧‧Speaker

113‧‧‧Noise reduction processor

12‧‧‧Sound filter

8‧‧‧Recipient

81‧‧‧Ear Canal

Claims (10)

An active noise reduction device with a sound filter, comprising: a housing including first and second passages, the length of the passage between the first inner end and the first outer end of the first passage is greater than that of the second passage The length of the channel between the second inner end and the second outer end; an active noise reduction unit, including: an external microphone, arranged outside the housing, to detect an environmental noise, where the external microphone detects The position is close to the position of the first outer end; a speaker is arranged at the second outer end to output the inverted signal of the environmental noise; and a noise reduction processor is electrically coupled to the external microphone and the speaker, wherein The noise reduction processor performs the inverted signal and phase adjustment according to the difference between the time when the inverted signal of the environmental noise output by the speaker passes through the second channel and the time when the environmental noise passes through the first channel, so that The ambient noise and its inverted signal achieve a superimposing effect at the exit area of the first inner end of the first channel and the second inner end of the second channel; and a sound filter is arranged in the first channel. The active noise reduction device with a sound filter as described in item 1 of the scope of patent application, wherein the first channel is located on one side of the second channel. The active noise reduction device with a sound filter as described in item 1 of the scope of patent application, wherein the first channel includes a first outer channel, a first inner channel, and a second inner channel, and the first outer channel is connected at the same time The first inner channel and the second inner channel, and the first inner channel and the second inner channel are located on both sides of the second channel. The active noise reduction device with a sound filter as described in item 3 of the scope of patent application, wherein the sound filter is located in the first outer channel. The active noise reduction device with sound filter as described in the first item of the scope of patent application, wherein the first channel further includes a low-pass filter tubular shape with a cavity for To house the sound filter. The active noise reduction device with a sound filter as described in item 1 of the scope of patent application, wherein the sound filter and the active noise reduction unit form a band-pass filter. An over-ear earphone includes: an earmuff; and the active noise reduction device with a sound filter as described in item 1 of the scope of patent application, which is arranged in the earmuff. An in-ear earphone includes: an earphone shell; and the active noise reduction device with a sound filter as described in the first item of the scope of patent application, which is arranged in the earphone shell. The in-ear earphone described in item 8 of the scope of patent application, wherein the shell and the earphone shell are integrally formed with the same material. The in-ear earphone described in item 9 of the scope of patent application further includes a protrusion located at an outer end of the earphone housing, and the protrusion has a channel for allowing sound to enter the earphone housing.

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