JP2008141456A - Acoustic system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the sound quality of music emitted from a portable terminal or the like without needing an active means such as a special amplifier and a speaker at the outside. <P>SOLUTION: Units 104 and 105 respectively receive sound received from a speaker position 102 of the portable terminal 101 in a cavity A and emit the sound in the direction of the front by a reflecting plate 106 as it is. The cavity A is connected to a cavity B wider than the cavity A, and is further connected to a cavity C (including space behind the reflecting plate 106) much wider than the cavity B through ducts A and B. The cavities B and C are provided with passive sound emitting plates A and B having a resonance frequency of a low-pitched side of the sound received from the speaker position 102. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an audio device that can be connected to a portable terminal having a speaker to improve the sound quality of the speaker.

  At present, with mobile terminals such as mobile phones, with the increasing number of functions, there are models that have left and right speakers and can take in music data such as incoming melody and music from outside and play them in stereo.

In order to obtain sufficient volume and high-quality sound output in music playback on such a mobile terminal, at least a part of the sound generated from the left and right speakers in the state where the mobile terminal is held on the desktop holder is displayed in front. There has been proposed a technique including a direction changing means for directing in a direction (see Patent Document 1).
JP 2005-136895 A

  However, the shape of the speaker that reproduces and emits music is also restricted due to the physical limitations of the portable terminal, and sufficient characteristics are not obtained with respect to the frequency characteristics of the reproduced sound source.

  Speakers mainly intended for music playback on mobile devices cannot structurally reproduce low frequencies (for example, bands below 500 Hz), and the sound quality of music sources such as ringtones has improved. It cannot be denied that the characteristics are poor. In particular, decay is remarkable in the low frequency range, and in some cases, musicality may be impaired in some cases.

  According to a desktop holder called a cradle equipped with a dedicated amplifier and speaker (sometimes also used as a charging device), improvement in sound quality and volume can be expected, but to provide a dedicated amplifier and speaker outside There is a corresponding extra cost.

  The present invention has been made in view of such a background, and improves the sound quality of music emitted from a portable terminal or the like without requiring active means such as a special amplifier or speaker outside. It is an object of the present invention to provide an audio device capable of

  The acoustic device according to the present invention includes a box-shaped member having a sound receiving opening that is in close contact with a sound emitting opening of a speaker capable of reproducing music, the box-shaped member including a first chamber having the sound receiving opening, A second plate that communicates with the space of the first chamber and that is wider than the first chamber, and in the first chamber, a radiation plate that emits the sound received from the sound emission opening in the front direction is provided, The chamber is provided with a passive sound emitting member having a resonance frequency on the low frequency side of the sound.

  The second chamber forms a larger space than the first chamber, and the low frequency range is emphasized by the passive sound emitting member having a resonance frequency on the low frequency side of the sound. That is, by resonating the passive sound emitting member with low-frequency overtones that cannot be reproduced due to speaker characteristics, the overtones are emphasized. As a result, since the fundamental wave can be perceived as a virtual bass as is known psychoacoustically, the frequency characteristics of the low range are improved.

  Preferably, the box-shaped member includes a third chamber that is wider than the second chamber and communicates with the space of the first chamber or the second chamber, and the second passive sound emitting member is provided in the third chamber. Provided. Thereby, the low frequency is further emphasized, and the low frequency is emphasized together with the second chamber.

  One passive sound emitting member may have a form capable of resonating at a plurality of frequencies. By increasing the resonance frequency, although it is a discrete resonance frequency, since the band between the resonance frequencies is also enhanced, an improvement in the low band can be expected in a wide low band.

  According to the present invention, it is possible to improve the sound quality of the music emitted from the mobile terminal, particularly the low-frequency sound quality, without adding a special amplifier or speaker outside.

  Since it does not depend on active means using a power source such as an amplifier and a speaker, an acoustic device can be provided at a relatively low cost. In addition, since the sound device itself does not require a power source, it can be used even in an environment where there is no external power source.

  If the connection with the speaker of the mobile terminal is devised, it can be applied to an existing mobile terminal.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings.

  FIG. 1 shows a schematic configuration in a state where the acoustic device according to the present embodiment is combined with a portable terminal.

  In this example, the acoustic device includes a right unit 104 and a left unit 105, which are symmetrically configured with box-shaped members, respectively. A portable terminal 101 to which this acoustic device is applied includes a pair of speakers for stereo reproduction on the left and right side surfaces of the casing. When using the audio device, the portable terminal 101 is held between the left and right units 104 and 105. Here, the mobile terminal 101 is assumed to be a mobile phone terminal. The form is not particularly limited, such as a folding type, a slide type, and a straight type. A display unit such as an LCD of a mobile phone terminal and an operation unit such as a numeric keypad are not shown. It is assumed that the screen of the display unit is facing the front of the figure.

  In the state shown in FIG. 1, the sound outlet of the speaker of the portable terminal 101 is in close contact with the speaker position 102 provided on the side surface of each unit. The speaker position 102 corresponds to a sound receiving port of each unit. Here, “closely” means that sound emitted from the speaker is transmitted to the units 104 and 105 so as not to leak outside as much as possible. It does not matter whether the sound outlet of the speaker is in direct contact with the sound receiver of the unit or connected via something like a guide. The mechanical connection structure for maintaining the close contact state is not particularly limited.

  Since the left and right units 104 and 105 have a symmetrical structure as described above, only the right unit 104 will be described in detail below.

  The right unit 104 has a substantially rectangular parallelepiped box-like shape combining left and right side plates, front plate, back plate, top plate, and bottom plate made of any material such as wood, plastic, etc. It is partitioned into spaces. These spaces are called “cavities” in the present embodiment. The three cavities A (first chamber) 112, cavity B (second chamber) 114, and cavity C (third chamber) 116 are gray for convenience, as shown in FIGS. 2 (a), (b), and (c). They are shown separately by painting.

  The right unit 104 is partitioned by horizontal partition plates 121 and 122 that are separated from each other in the vertical direction. However, both the left and right sides of the partition plates 121 and 122 are slightly separated from the left and right side plates of the right unit 104.

  In addition, the space above the partition plate 121 is divided into two by the reflection plate 106 that is slanted between the front plate and the rear plate of the right unit 104. In this way, a triangular prism-shaped cavity A112 as shown in FIG. 2A is formed. An opening 109 is provided in a part of the partition plate 121 that hits the bottom surface of the cavity A, whereby sound energy is conducted from the cavity A112 to the cavity B114 below it. The front portion of the right unit 104 that hits the front surface of the cavity A112 is not particularly shown, but has a large opening or a large number of smaller openings so that the sound reflected by the reflector 106 is emitted forward. A decorative cover such as a cloth may be attached to the front portion. Such a decorative cover may cover only the front surface of the cavity A, or may cover the entire front surface of the right unit 104. The sound emitted from the speaker is directed toward the listener through the reflector 106. As a result, sound is not diffused and sound pressure in the required direction is ensured.

  The cavity B114 is surrounded by the vertical partition plates 131 and 132 that form the duct A110 and the duct B108 between the horizontal partition plates 121 and 122 and the side plate of the right unit 104, and the front and rear plates of the right unit 104. It is a space (FIG. 2B). A passive sound emitting plate (first passive sound emitting member) A107 called a passive radiator or drone cone is provided on the front surface of the cavity B114. One passive sound emitting plate A107 is set in a form (for example, an elliptical shape) that resonates at a desired plurality of frequencies. These desired multiple frequencies are frequencies that belong to the low range when the sound emitted from the speaker is divided into a mid-high range and a low range. The relationship between the two resonance frequencies is not indispensable, but here, the higher resonance frequency is set to a resonance frequency of 2fa0 with respect to one lower resonance frequency fa0.

  The cavity C116 is configured by a rectangular parallelepiped space below the partition plate 122 and a space on the back side of the reflector 106 connected to the space via the duct 108, and a sealed space necessary for desired frequency resonance is formed. Secured. In FIG. 2C, the space of the duct A110 is also shown to be included in the cavity C116. However, since the spaces of the ducts A and B are relatively small, it may be considered that they are not included in the cavity C116. A passive sound emitting plate (second passive sound emitting member) B111 similar to the passive sound emitting plate A107 is also provided on the front surface of the cavity C116. This passive sound emitting plate B111 is also set to have two resonance frequencies. Here, the relationship between the two resonance frequencies is not essential, but here, the relationship between the resonance frequency of 2 fb0 and the resonance frequency fb0 of one low is used. fb0 is a frequency lower than fa0. A resonance circuit capable of emitting resonance energy in a wide band can be configured by appropriately arranging the resonance frequencies fa0 and fb0.

  The two resonance frequencies of the passive sound emission plate B are set to be lower than the two resonance frequencies of the passive sound emission plate A, but the upper resonance frequency of the two resonance frequencies of the passive sound emission plate B is set. May be set to be higher than the lower resonance frequency of the two resonance frequencies of the passive sound emitting plate A.

  If this band is made to coincide with the attenuation region of the low frequency of the speaker, when a signal near the resonance frequency is emitted in that frequency region, the level of the signal that matches the resonance frequency is low. Also, a resonance known as Helmholtz resonance occurs, and the sound pressure near that frequency rises. In this band, a harmonic overtone component having a lower frequency than this is also included. The fundamental wave is lost due to the characteristics of the speaker, but the harmonic component is emphasized in a wide band by this resonance circuit, so that the harmonic that is known psychoacoustically is emphasized. As a result, a virtual bass effect that can perceive the fundamental component is obtained, and the fundamental component that was originally lost along with the sound in the decay region of the speaker can be perceived, resulting in an effect that the low range of the speaker is expanded. . Next, this effect will be further explained.

  The graph of FIG. 3 shows how the characteristics of a speaker used in a portable terminal or the like behave with respect to a low-frequency signal included in music or the like, as an example of the relationship between reproduced sound and speaker characteristics. The Y axis indicates the level indicating the signal magnitude, and the X axis indicates the frequency. Let f0 be the fundamental frequency of a certain signal. A signal generated from an instrument included in a musical piece or the like is not composed only of a fundamental wave, and a tone unique to the instrument is produced by a plurality of overtones such as 2f2f0, 3f3f0, 4x4f0, etc. . In particular, it is difficult to perceive only the fundamental wave if there is no overtone at low frequencies. However, as described above, since the size of the speaker of the portable terminal is suppressed due to physical limitations, as shown in the speaker characteristic 303, the frequency is lower from the higher frequency than the low basic signal inherent to the music. The characteristics are degraded on the band side. As a result, the loss component 308 indicated by the dotted lines of the fundamental wave f0, the second harmonic 2f0, and the third harmonic 3f0 is generated, and the component is far from the original tone. This has led to sound quality degradation in the low frequency range.

  Here, the virtual bass perception will be mentioned again. In psychoacoustic terms, even if the fundamental wave f0 is lost, it can be perceived as if the fundamental wave f0 is being output by emphasizing harmonic components such as the second harmonic 2f0 and the third harmonic 3f0 by some means. This is called virtual bass. Therefore, if there is a harmonic overtone trace of a certain waveform represented by the sound emission component 309, it can be brought close to the original tone by emphasizing the trace.

  Next, the principle of the present invention is released.

  The graph of FIG. 4 represents the characteristics of the acoustic device based on the present embodiment shown in FIG. The Y axis indicates the level indicating the signal magnitude, and the X axis indicates the frequency. The passive sound emission plate B resonance characteristic 408 having a plurality of resonance frequencies is set to have a resonance frequency 2fb0 that is twice as much as the lower resonance frequency fb0, and shows the frequency characteristic. Similarly, the resonance characteristic 410 of the passive sound emission plate A having a plurality of resonance frequencies is set so as to have a resonance frequency 2fa0 that has a double relationship with respect to the lower resonance frequency fa0. ing.

  A characteristic produced by two of the passive sound emission plate B resonance characteristic 408 and the passive sound emission plate A resonance characteristic 410 is indicated by a passive sound emission plate resonance synthesis characteristic 409. As described above, the level is increased or decreased depending on the frequency, but the enhancement using the resonance phenomenon is possible in the necessary band. In addition, a total sound emission characteristic 411 is obtained as a final frequency characteristic from the original speaker characteristic 407. As shown by this characteristic, an improvement in the attenuation region of the speaker characteristic 407 can be expected, and a virtual bass effect can be obtained by emphasizing the overtone component generated in this frequency region.

  As described above, according to the present embodiment, it is possible to provide a user with music reproduction with rich sound quality without using a special amplifier, speaker, or signal processing.

  FIG. 5 shows a schematic configuration in a state where the acoustic device according to the second embodiment of the present invention is combined with a portable terminal. Elements that are the same as those shown in FIG. 1 are given the same reference numerals, and redundant descriptions are omitted.

  In this embodiment, the configuration corresponds to the case where the speaker position 102 of the portable terminal 101 exists near the center of the side portion. Therefore, as shown more clearly in FIG. 6, the vertical positions of the cavity A112 and the cavity B114 are reversed from the configuration of FIG. In order to obtain such a cavity configuration, a rectangular partition plate 141 that partitions the cavity A112 and the cavity B114, and a triangular partition plate 142 that partitions the cavity A112 and the cavity C116 are provided. Like the partition plate 121, the partition plate 141 has an opening 109, but the left and right sides are in contact with the side plate. A slit-shaped opening 143 is provided on the terminal side of the triangular partition plate 142. The shape of the opening 143 is not limited to the slit shape, and may be one or a plurality of through holes having an arbitrary shape. In addition, the space below the partition plate 142 is connected to the triangular prism-shaped space behind the reflecting plate 106 through the triangular opening 144 to form a cavity C116.

  Even with such a configuration, substantially the same effect as in the first embodiment can be obtained.

  FIG. 7 shows a schematic configuration in a state where the acoustic device according to the third embodiment of the present invention is combined with a portable terminal. In this embodiment, a base unit 150 connected in common to the left and right units in FIG. 1 is connected. The base unit 150 includes a new cavity D (fourth chamber) 118. In order to allow the cavity D118 to communicate with the cavity C116, slit-shaped openings 151 are provided in the bottom plates of the left and right units 104 and 105 so that the sound energy in the cavity C is propagated to the larger fourth cavity D118. . The shape of the opening 151 is not limited to the slit shape, and may be one or a plurality of through holes having an arbitrary shape. In the cavity D118, a larger passive sound emission plate C (third passive sound emission member) 152 may be provided. With this configuration, it is possible to provide another resonance frequency on the lower frequency side and improve the overall sound emission characteristics of the acoustic device.

  Although not shown, a similar cavity D118 can be added to the acoustic device of the second embodiment.

  Here, a schematic internal configuration of a mobile phone terminal will be described with reference to FIG. 8 as a representative example of the mobile terminal 101.

  The control unit 200 includes a CPU, and performs various controls of the terminal via the control line 205 based on the OS and various programs stored in the memory unit 205.

  The communication antenna 202 is, for example, a built-in antenna, and transmits and receives signal radio waves for calls and packet communication. The communication circuit 201 performs frequency conversion, modulation, demodulation, and the like of transmission / reception signals.

  When voice call reception data is supplied from the communication antenna 202 and the communication circuit 201, the voice processing unit 212 decodes the call voice reception data and transmits the decoded call voice data via the data line 208. Send to speaker 210.

  The speakers 210 and 211 are left and right speakers corresponding to the right unit 104 and the left unit 105 described above, and output the voice data, the ringer sound, and the reproduced music data after digital-analog conversion and amplification. As a result, call voice, ringer sound, and playback music can be obtained.

  The receiver 212 is an ear receiver for reception, includes a digital-analog converter and an amplifier, and outputs voice data after performing digital-analog conversion and amplification.

  The microphone 211 is a microphone for transmission, and includes an analog-digital converter and an amplifier. The call voice signal input via the microphone 211 is amplified to a predetermined level by an amplifier, converted to digital voice data by an analog-digital converter, and sent to the voice processing unit 212 via the data line 208. After being encoded, the data is sent to the communication circuit 201 via the data line 208, subjected to various processes such as modulation and frequency conversion, and transmitted from the communication antenna 202.

  The display unit 203 includes a display composed of an LCD or the like and a display driving circuit for driving the display. The display driving circuit drives the display based on the image signal supplied from the image processing unit 213. Thereby, an image, a character, etc. are displayed on a display.

  The image processing unit 213 processes an image displayed on the display unit 203. Further, the image processing unit 213 performs decompression decoding on the compression-coded image data read from the memory unit 205 under the control of the control unit 200, image data acquired via the Internet, and the like. Then, the decompressed and decoded image data is sent to the display unit 203 via the data line 208 and displayed.

  The operation unit 204 includes an operation device such as a keyboard provided on the casing of the mobile phone terminal according to the present embodiment, and an operation signal generator that generates an operation signal corresponding to the operation of the operation device.

  The memory unit 205 includes a ROM (Read Only Memory) and a RAM (Random Access Memory). The ROM is an OS (Operating System), control program code for the control unit 200 to control each part, various initial setting values, font data, dictionary data used for kana-kanji conversion and prediction conversion, ringtones and key operation sounds. And the like, the control program code of the display processing according to the present embodiment, the program code for various applications installed in the terminal, the device identification information (ID) of the terminal, and the like are stored. This ROM includes a rewritable ROM such as NAND-type flash memory (NAND-type flash memory) or EEPROM (Electrically Erasable Programmable Read-Only Memory), e-mail data, telephone book and e-mail address book data, It is also possible to store various data such as schedule book data, various data such as communication history, user dictionary data, still image and moving image data, sound data such as key operation sounds, and various user setting values. The RAM stores data as needed as a work area or a temporary data storage area when the control unit 200 performs various data processing.

  In addition, although not shown in FIG. 8, the terminal of this embodiment includes a camera unit, an external memory interface, an external cable connector, an infrared communication function, an electronic wallet function, a vibrator, a battery, a power control function, and the like. Also, each component included in a general mobile phone terminal is provided. The description of the circuit configuration and other configurations provided in these general mobile phone terminals will be omitted.

  The preferred embodiments of the present invention have been described above, but various modifications and changes other than those mentioned above can be made. For example, although the mobile terminal has been described as a mobile phone terminal, it may be a mobile music player, a PDA, a game machine, or the like. The acoustic device of any of the above-described embodiments (particularly the third embodiment) may have a charging function for charging the secondary battery of the mobile terminal.

It is a figure which shows the schematic structure of the state which combined the acoustic device in embodiment of this invention with the portable terminal. It is the figure which distinguished and showed three cavities of the audio equipment shown in FIG. As an example of the relationship between reproduced sound and speaker characteristics, it is a graph showing how the characteristics of a speaker used in a portable terminal or the like behave with respect to a low-frequency signal included in music or the like. It is a graph showing the characteristic of the audio equipment based on embodiment of this invention shown in FIG. It is a figure which shows the structure of the outline of the state which combined the acoustic device in the 2nd Embodiment of this invention with the portable terminal. It is the figure which distinguished and showed three cavities of the acoustic apparatus shown in FIG. It is a figure which shows the structure of the outline of the state which combined the acoustic device in the 3rd Embodiment of this invention with the portable terminal. It is a figure which shows schematic internal structure of the mobile telephone terminal in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Portable terminal, 102 ... Speaker position, 104 ... Right unit, 105 ... Left unit, 106 ... Reflecting plate, 107 ... Passive sound emission board A (1st passive sound emission member), 108 ... Duct B, 109 ... Opening 110, Duct A, 111 Passive sound emitting plate B (second passive sound emitting member), 112 ... Cavity A, 114 ... Cavity B, 116 ... Cavity C, 118 ... Cavity D, 121, 122 ... Horizontal Partition plate 131, 132 ... Vertical partition plate, 141, 142 ... Partition plate, 143, 144 ... Opening, 150 ... Base unit, 151 ... Opening, 152 ... Passive sound emission plate C (third passive sound emission member) , 200 ... control unit, 203 ... display unit, 204 ... operation unit, 210, 211 ... speaker, 303 ... speaker characteristics, 308 ... loss component, 309 ... sound emission component, 407 ... speaker Sex, 408 ... passive sound board B resonance characteristic, 409 ... passive sound board resonance combined characteristic, 410 ... passive sound board A resonance characteristic, 411 ... Overall sound emission characteristics

Claims (7)

A box-shaped member having a sound receiving opening that is in close contact with a sound emitting opening of a speaker capable of reproducing music;
This box-shaped member
A first chamber having the sound receiving port;
A second chamber that is wider than the first chamber and communicates with the space of the first chamber;
In the first chamber, a radiation plate that emits the sound received from the sound emission opening in a front direction is provided,
In the second chamber, a passive sound emitting member having a resonance frequency on the low frequency side of the sound is provided.   The box-shaped member includes a third chamber that is wider than the second chamber and communicates with the space of the first chamber or the second chamber, and the third chamber includes a passive sound emitting member of the second chamber. 2. The acoustic device according to claim 1, further comprising a second passive sound emitting member having a resonance frequency lower than the resonance frequency.   The acoustic device according to claim 1, wherein one passive sound emitting member has a form capable of resonating at a plurality of frequencies.   The acoustic device according to claim 3, wherein the second resonance frequency is twice the first resonance frequency.   The acoustic device according to claim 3 or 4, wherein the passive sound emitting member has an elliptical shape. A pair of units having a symmetrical configuration;
It has a base unit that is commonly connected to both units,
Each of the pair of units is
A box-shaped member having a sound receiving opening that is in close contact with a sound emitting opening of a speaker capable of reproducing music;
This box-shaped member
A first chamber having the sound receiving port;
A second chamber wider than the first chamber, communicating with the space of the first chamber;
Forming a third chamber wider than the second chamber, communicating with the space of the first chamber or the second chamber;
In the first chamber, a radiation plate that emits the sound received from the sound emission opening in a front direction is provided,
The second chamber has a first passive sound emitting member,
A space larger than the second chamber is formed in the third chamber, and a second passive sound emitting member is provided,
The base unit forms a fourth chamber communicating with the third chambers of both of the pair of units.   The acoustic device according to claim 6, wherein a third passive sound emitting member having a resonance frequency lower than a resonance frequency of the passive sound emitting member of the third chamber is provided in the fourth chamber.