WO2010021414A1

WO2010021414A1 - Headphone

Info

Publication number: WO2010021414A1
Application number: PCT/KR2008/004777
Authority: WO
Inventors: Jong-Bae Lee
Original assignee: Cresyn Co.,Ltd
Priority date: 2008-08-18
Filing date: 2008-08-18
Publication date: 2010-02-25
Also published as: KR101107598B1; KR20110021870A

Abstract

Headphones are disclosed that can remove noise input from external sources. The headphone includes a microphone, an attenuation circuit, first and second speakers, and a headphone housing. The attenuation circuit generates attenuation signals of first and second frequency bands that are different from each other. The first and second speakers output the attenuation sounds according to the attenuation signals of the first and second frequency bands, respectively. The headphones allow a user to select one of the modes according to the degree of external noise and thus can effectively remove the input external noise, so that the user can listen to a high quality audio sound that is close to the original audio sound.

Description

Description HEADPHONE

Technical Field

[1] The present invention relates to headphones, and more particularly, to headphones that can remove noise input from external sources. Background Art

[2] Headphones are used for listening to music, etc. without interference from peripheral noise. When users wear headphones in noisy areas, such as airplanes, trains, construction sites, etc., they cannot clearly hear the music from the speakers in their headphones due to peripheral noise.

[3] In order to resolve this problem closed-type headphones are worn by users to block external noise in a passive mode. Closed-type headphones are classified into supra- aural headphones, which cover the ear to block external noise, and in-ear headphones that are inserted into the ear canal. In particular, supra-aural headphones include around-ear headphones, which completely cover the ear to block external noise, and on-ear headphones that sit on the ears.

[4] In recent years, a technique has been developed which can actively cancel external noise in headphones. The technique processes external noise as follows: detecting external noise through a microphone; analyzing the detected external noise; generating an attenuation sound whose phase is opposite to that of the external noise; and outputting the attenuation sound to thus cancel the external noise.

[5] In Japanese Patent Publication No. 2001-69590 entitled NOISE REDUCTION

HEADSETS, the headphones were disclosed where a single speaker outputs both an audio sound and an attenuation sound whose phase is opposite to that of noise. In Korean Patent Publication No. 10-2005-0083324 entitled NOISE REMOVING HEADPHONES, the headphones were disclosed where two speakers are mounted, one outputs an audio sound and the other outputs an attenuation sound whose phase is opposite to that of noise. Disclosure of Invention

Technical Problem

[6] The present invention solves the above problems, and provides headphones that can remove noise input from external sources.

Technical Solution [7] In accordance with an exemplary embodiment of the present invention, the present invention provides a noise removal headphone including: a microphone for detecting external noise; an attenuation circuit for analyzing the detected external noise and generating attenuation signals whose phases are opposite to that of the analyzed noise; first and second speakers for outputting attenuation sounds according to the attenuation signals; and a headphone housing for receiving the first and second speakers. Here, the attenuation signals are in first and second frequency bands which are different from each other. The first speaker outputs the attenuation sound according to the attenuation signal of the first frequency band and the second speaker outputs the attenuation sound according to the attenuation signal of the second frequency band.

[8] Preferably, the first and second speakers further output audio sounds according to electrical signals input thereto, respectively.

[9] In accordance with another exemplary embodiment of the present invention, the present invention provides a noise removal headphone including: a microphone for detecting external noise; an attenuation circuit for analyzing the detected external noise and generating at least one of the attenuation signals whose phases are opposite to that of the analyzed noise, wherein the attenuation signals are in first and second frequency bands that are different from each other; a first speaker for outputting an audio sound according to an input electrical signal; a second speaker for outputting attenuation sounds according to the attenuation signals generated in the attenuation circuit; a headphone housing for receiving the first and second speakers; and a switch for selecting one of the attenuation sounds according to the attenuation signals of the first and second frequency bands, wherein the selected attenuation sound is output through the second speaker.

[10] Preferably, the attenuation circuit generates at least one of the attenuation signal of the first frequency band and the attenuation signal of the second frequency band, according to an operation state of the switch.

[11] Preferably, the attenuation circuit digitally generates the attenuation signals.

[12] In accordance with another exemplary embodiment of the present invention, the present invention provides a noise removal headphone including: a first mode where first and second speakers output attenuation sounds whose phases are opposite to the phase of external noise; and a second mode where the first speaker outputs an audio sound and the second speaker outputs the attenuation sounds.

[13] Preferably, the first mode allows the first speaker to output the attenuation sound according to an attenuation signal of a first frequency band and the second speaker to output the attenuation sound according to an attenuation signal of a second frequency band that is different from that attenuation signal of the first frequency band.

[14] Preferably, the first and second speakers further output audio sounds according to electrical signals input thereto, respectively.

[15] Preferably, the second mode allows the second speaker to select and output the attenuation sound according to an attenuation signal of a first frequency band or the at- tenuation sound according to an attenuation signal of a second frequency that is different from the attenuation sound according to an attenuation signal of a first frequency band.

[16] Preferably, the headphone further includes a third mode that allows the first and second speakers to output audio sounds.

[17] Preferably, the third mode allows the first speaker to output an audio sound of a particular frequency band and the second speaker to output an audio sound of another frequency band that is different from the particular frequency band.

Advantageous Effects

[18] As described above, since the headphone of the present invention allows a user to select one of the modes according to external noise and effectively removes the external noise, the user can listen to a high quality audio sound that is close to the original one. Brief Description of Drawings

[19] The features and advantages of the present invention will be more apparent from the following detailed description in conjunction with the accompanying drawings, in which:

[20] Figure 1 is an exploded perspective view illustrating a headphone according to an embodiment of the present invention;

[21] Figures 2A and 2B are perspective views illustrating a headphone when the disassembled parts in Figure 1 are assembled;

[22] Figure 3A is a graph describing a state where external noise is reduced by one speaker placed within a headphone;

[23] Figure 3B is a graph describing a state where external noise is reduced when the headphone is set to mode 1 ;

[24] Figure 4 is a table describing audio sounds output from respective speakers when the headphone is set to one of a plurality of modes; and

[25] Figure 5 is a schematic block diagram of a headphone, according to the present invention, illustrating elements when it is operated.

[26] <Brief Description of Symbols in the Drawings>

[27] 100, 100a, 100b: headphone

[28] 110: headphone housing

[29] 120: speaker plate

[30] 130: microphone

[31] 140: attenuation circuit

[32] 150: cover

[33] 160: ear pad [34] 172: first speaker

[35] 174: second speaker

[36] 182, 184: controller

[37] 182a, 184a: power switch

[38] 182b, 184b: selection switch

Best Mode for Carrying out the Invention

[39] Hereinafter, embodiments of the present invention are described in detail with reference to the accompanying drawings.

[40] Figure 1 is an exploded perspective view illustrating a headphone according to an embodiment of the present invention. Figures 2A and 2B are perspective views illustrating a headphone when the disassembled parts in Figure 1 are assembled.

[41] Referring to Figures 1 and 2, the headphone (100, 100a, or 100b) includes a headphone housing 110, a speaker plate 120, a microphone 130, an attenuation circuit 140, a cover 150, an ear pad 160, speakers 172 and 174, and a controller (182 or 184).

[42] The headphone housing 110 forms a receiving space whose front is opened there within and is coupled to the rear side of the speaker plate 120.

[43] The speaker plate 120 serves to mount the speakers 172 and 174 into the receiving space of the headphone housing 110. The speaker plate 120 forms at least one or more holes in a part thereof to pass the audio sound from the speakers 172 and 174 to the outside.

[44] It should be understood that the holes may be variously formed in terms of shape and structure.

[45] The microphone 130 is fixedly mounted to the speaker plate 120 and detects sounds, i.e., external noise, input from the outside of the headphone (100, 100a, or 100b). The microphone 130 is generally mounted as close as possible to the front of the speaker 140.

[46] The attenuation circuit board 140 is placed at the rear side of the speakers 172 and

174. The attenuation circuit analyzes the external noise detected by the microphone 130 and generates an attenuation signal to cancel the external noise entered in the headphone.

[47] It is preferable that the attenuation circuit generates an attenuation signal in a digital method. Because an analog method cannot generate an attenuation signal in a particular frequency band, that is, it can just generate an attenuation signal of a frequency in the vicinity of a particular frequency band. On the contrary, the digital method can generate an attenuation signal in a particular frequency band. For example, when it is selected that an attenuation signal of approximately 300 Hz can be generated, the digital method just generates an attenuation signal of approximately 300 Hz, but the analog method generates an attenuation signal of 250-350 Hz.

[48] The cover 150 covers the front side of the speaker plate 120 and forms audio sound through-holes finely which the audio sounds from the speakers 172 and 174 pass though. The cover 150 is coupled to the ear pad 160.

[49] The ear pad 160 is a member contacting the ear when a user wears the headphone. It is configured in such a way that a buffering member, such as a ring-type sponge, etc., is covered by an outer skin, such as a synthetic resin, leather, cloth, etc. The ear pad 160 fits around the cover 150.

[50] The speakers 172 and 174 are mounted in the receiving space of the headphone housing 110 through the speaker plate 120. The speakers 172 and 174, placed at the rear side of the microphone 130, output audio sounds according to input electrical signals. For the purpose of convenient description, the speaker 172 is called a first speaker and the speaker 174 is referred to as a second speaker. The headphone employs two speakers in the embodiment of the present invention, however, it is understood that the number of speakers can be increased as occasion demands.

[51] The first speaker 172 and second speaker 174 output: audio sounds according to electrical signals input thereinto, respectively; and attenuation sounds for canceling the external noise detected by the microphone 130, according to attenuation signals. The first and second speakers 172 and 174 output audio sounds according to modes. The modes are set by a selection switch 182b of a controller 182 or a selection switch 184b of a controller 184.

[52] The controllers 182 and 184 include power switches 182a and 184a for switching on and off power to the attenuation circuit 140 and selection switches 182b and 184b for setting audio sound modes, correspondingly and respectively.

[53] The selection switch can be implemented by a sliding switch 182b, as shown in

Figure 2A, which moves based on steps that correspond to modes. The selection switch can also be implemented by a push button switch 184b, as shown in Figure 2B, which selects one of the modes by pushing. When the power switch (182a, 184a) is switched on and the selection switch (182b, 184b) is set to one of modes 1, 2 and 3, the first and second speakers 172 and 174 output audio sounds in the selected mode.

[54] It should be understood that the controller (182, 184) can be mounted on outer surface of the headphone housing 110 or variously implemented in shape and structure, only if it can allow a user to easily operate power on/off and select modes.

[55] <Mode 1>

[56] When the power switch (182a, 184a) is switched on to supply power to the attenuation circuit 140 and the selection switch (182b, 184b) is set to mode 1, the first and second speakers 172 and 174 output both audio sounds according to input electrical signals and an attenuation sound generated by the attenuation circuit 140 according to an attenuation signal.

[57] The attenuation circuit 140 generates attenuation signals of first and second frequency bands that are different from each other. The first speaker 172 outputs an audio sound and an attenuation sound according to an attenuation signal of a first frequency band. Similarly, the second speaker 174 outputs an audio sound and an attenuation sound according to an attenuation signal of a second frequency band.

[58] In an embodiment of the present invention, the headphone (100, 100a, 100b) sets the center frequencies of the first and second frequency bands to 200 Hz and 300 Hz, respectively, to attenuate noise, such as approximately 250 Hz, which is generate at places, such as in an airplane.

[59] In the following description, comparison of reducing external noise is explained between a case where one speaker is placed in a headphone and a case where a plurality of speakers, i.e., first and second speakers 172 and 174, are placed in a headphone, with reference to Figure 3 A and 3B.

[60] Figure 3A is a graph describing a state where external noise is reduced by one speaker placed within a headphone. Figure 3B is a graph describing a state where external noise is reduced when the headphone is set to mode 1, where curve A indicates a state where external noise is reduced by the first speaker and curve B shows a state where external noise is reduced by the second speaker.

[61] 0 dB is a reference value as a relative value, which is determined when the attenuation circuit 140 is powered off. Based on the reference value, it is described how external noise is removed.

[62] As shown in Figure 3A, the curve indicates that the one speaker outputs an attenuation sound of a frequency band of approximately 200 Hz to cancel external noise, approximately 20 dB.

[63] When a headphone (100, 100a, 100b) is configured to place the first and second speakers 172 and 174 there within, which can output attenuation sounds of 200 Hz and 300 Hz, external noise of approximately 16 dB can be cancel as shown by the curve in Figure 3B.

[64] More specifically, as the first speaker 172 outputs an attenuation sound of a frequency band of approximately 200 Hz, external noise of approximately 10 dB is cancelled. Similarly, the second speaker 174 outputs an attenuation sound of a frequency band of approximately 300 Hz, and thus external noise of approximately 10 dB is cancelled. That is, since both the first and second speakers 172 and 174 output the attenuation sounds and simultaneously cancel external noise, they can cancel more amount of external noise than only a single speaker that outputs an attenuation sound of a frequency band of approximately 200 Hz.

[65] Therefore, the headphone with the first and second speakers 172 and 174, according to the present invention, cancel external noise more effectively than the conventional headphone with a single speaker for removing noise.

[66] When a user sets his/her wearing a headphone (100, 100a, 100b) to mode 1 at a noisy place, the headphone can effectively cancel external noise and allow the user to listen to an audio sound close to the original one.

[67] Furthermore, when the headphone with the first and second speakers 172 and 174 is operated such that they output only attenuation sounds according to attenuation signals of first and second frequency bands which are different from each other and thus remove external noise, it serves as only a noise canceling headphone, not a headphone for listening to audio sounds.

[68] <Mode 2>

[69] When an audio sound and an attenuation sound that cancels external noise are output from a single speaker, a problem occurs that the audio sound is overlapped with the attenuation sound and thus output with a characteristic different from that of the original audio sound.

[70] When a headphone with first and second speakers 172 and 174 is set to mode 1, the audio sound and the attenuation sound, simultaneously output from the first and second speakers 172 and 174, are overlapped with each other as described above, so that the audio sound is output with a characteristic different from that of the original audio sound. Therefore, if the headphone is operated with mode 1 at a place where external noise is little and does not need to cancel, a user may have trouble listening to a high quality audio sound.

[71] In order to resolve this problem, the headphone (100, 100a, 100b) is set to mode 2, so that the audio sound output from the first and second speakers 172 and 174 can be controlled, which is described as follows.

[72] When the power switch (182a, 184a) is switched on to supply power to the attenuation circuit 140 and the selection switch (182b, 184b) is set to mode 2, the first speaker 172 outputs an audio sound according to an input electrical signal and the second speaker 174 outputs an attenuation sound according to an attenuation signal generated in the attenuation circuit 140. The attenuation circuit 140 generates at least one of the attenuation signals of the first and second frequency bands.

[73] In an embodiment of the present invention, the headphone sets the center frequencies of the first and second frequency bands to 200 Hz and 300 Hz, respectively, to attenuate noise, such as approximately 250 Hz, which is generate at places, such as in an airplane.

[74] In an embodiment of the present invention, the headphone (100, 100a, 100b) is set to mode 2-1 and mode 202 so that the second speaker 174 can selectively output an attenuation sound of a frequency band, approximately 200 Hz or 300 Hz. [75] When mode 2-1 is selected, the second speaker 174 outputs an attenuation sound of a frequency band of approximately 200 Hz.

[76] Similarly, when mode 2-2 is selected, the second speaker 174 outputs an attenuation sound of a frequency band of approximately 300 Hz. Since noise of approximately 300 Hz is generally generated in the airplane, the headphone removes noise more effective in mode 2-2 than mode 2-1.

[77] The headphone gives a user an option to compare and alter mode 2-1 and mode 2-2 at a little noisy place, so that the user can set the headphone to mode 2-1 or 2-2 that he or she feels more still and thus can listen to a high quality audio sound.

[78] That is, as a user wearing a headphone at a little noisy place sets the headphone to mode 2-2 where external noise is removed but does not affect an audio sound, thereby listening to the audio sound close to the original one.

[79] The headphone according to an embodiment of the present invention provides convenience to a user in such a way that it can allow the user to select one of the mode 2-1 and mode 2-2, which removes external noise more effectively than another, depending on external noise.

[80] <Mode 3>

[81] Since little noise is generated at a place, such as in a library, house, etc., a headphone does not require an external noise removing function.

[82] For such a situation, the headphone (100, 100a, 100b) has mode 3 where audio sounds output from the first and second speakers 172 and 714 are controlled, which is described in detail as follows.

[83] When the power switch (182a, 184a) is switched on to supply power to the attenuation circuit 140 and the selection switch (182b, 184b) is set to mode 3, the first and second speaker 172 output audio sounds according to input electrical signals. More specifically, the first speaker 172 outputs an audio sound of a particular frequency band and the second speaker 174 outputs an audio sound of another frequency band that is different from the particular frequency band of the first speaker 172.

[84] That is, since the headphone with first and second speakers 172 and 174 is operated in such a way that they output audio sounds of high and low frequency bands, respectively, it can reproduce audio sounds of a broader frequency band than a headphone with a single speaker and can allow a user to listen clearly to audio sounds.

[85] When a user sets his/her wearing a headphone (100, 100a, 100b) to mode 3 at a relatively quiet place, the headphone can allow the user to listen to an audio sound close to the original one.

[86] Figure 4 is a table describing modes 1, 2 and 3. More specifically, the table shows audio sounds output from a plurality of speakers (first and second speakers) when one of a plurality of modes (modes 1, 2-1, 2-2, and 3) is selected. [87] Figure 5 is a schematic block diagram of a headphone, according to the present invention, illustrating elements when it is operated.

[88] Referring to Figure 5, when the power switch (182a, 184a) is switched on and the selection switch (182b, 184b) is set to mode 1, the attenuation circuit 140 analyzes external noise detected by the microphone 130 and generates attenuation signals whose phases are opposite to that of the analyzed noise, where the attenuation signals are in first and second frequency bands which are different from each other. The first and second speaker 172 and 174 output attenuation sounds according to attenuation signals of first and second frequency bands, respectively. The first and second speakers 172 and 174 also output audio sounds according to input electrical signals.

[89] When mode 2 is selected, the attenuation circuit 140 generates at least one of the attenuation signals of the first and second frequency bands, the first speaker 172 outputs an audio sound according to an input electrical signal and the second speaker 174 outputs an attenuation sound according to an attenuation signal generated in the attenuation circuit 140. When mode 2-1 or 2-2 is selected, the second speaker 174 outputs an attenuation sound according to an attenuation signal of a first frequency band or a second frequency band.

[90] When mode 3 is selected, the first speaker 172 outputs an audio sound of a particular frequency band (high frequency band) and the second speaker 174 outputs an audio sound of another frequency band (low frequency band).

[91] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Industrial Applicability

[92] The present invention can be widely applied to audio systems and audio- system-related industrial fields.

Claims

[1] A noise removal headphone comprising: a microphone for detecting external noise; an attenuation circuit for analyzing the detected external noise and generating attenuation signals whose phases are opposite to that of the analyzed noise; first and second speakers for outputting attenuation sounds according to the attenuation signals; and a headphone housing for receiving the first and second speakers, wherein: the attenuation signals are in first and second frequency bands which are different from each other; and the first speaker outputs the attenuation sound according to the attenuation signal of the first frequency band and the second speaker outputs the attenuation sound according to the attenuation signal of the second frequency band.

[2] The headphone according to claim 1, wherein the first and second speakers further output audio sounds according to electrical signals input thereto, respectively.

[3] A noise removal headphone comprising: a microphone for detecting external noise; an attenuation circuit for analyzing the detected external noise and generating at least one of the attenuation signals whose phases are opposite to that of the analyzed noise, wherein the attenuation signals are in first and second frequency bands that are different from each other; a first speaker for outputting an audio sound according to an input electrical signal; a second speaker for outputting attenuation sounds according to the attenuation signals generated in the attenuation circuit; a headphone housing for receiving the first and second speakers; and a switch for selecting one of the attenuation sounds according to the attenuation signals of the first and second frequency bands, wherein the selected attenuation sound is output through the second speaker.

[4] The headphone according to claim 3, wherein the attenuation circuit generates at least one of the attenuation signal of the first frequency band and the attenuation signal of the second frequency band, according to an operation state of the switch.

[5] The headphone according to claim 1 or 3, wherein the attenuation circuit digitally generates the attenuation signals.

[6] A noise removal headphone comprising: a first mode where first and second speakers output attenuation sounds whose phases are opposite to the phase of external noise; and a second mode where the first speaker outputs an audio sound and the second speaker outputs the attenuation sounds.

[7] The headphone according to claim 6, wherein the first mode allows the first speaker to output the attenuation sound according to an attenuation signal of a first frequency band and the second speaker to output the attenuation sound according to an attenuation signal of a second frequency band that is different from that attenuation signal of the first frequency band.

[8] The headphone according to claim 7, wherein the first and second speakers further output audio sounds according to electrical signals input thereto, respectively.

[9] The headphone according to claim 6, wherein the second mode allows the second speaker to select and output the attenuation sound according to an attenuation signal of a first frequency band or the attenuation sound according to an attenuation signal of a second frequency that is different from the attenuation sound according to an attenuation signal of a first frequency band.

[10] The headphone according to claim 6, further comprising a third mode that allows the first and second speakers to output audio sounds.

[11] The headphone according to claim 10, wherein the third mode allows the first speaker to output an audio sound of a particular frequency band and the second speaker to output an audio sound of another frequency band that is different from the particular frequency band.