JP2005130156A - Sound reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound reproducing device incorporating a piezoelectric speaker as a sound output means. <P>SOLUTION: A portable MD reproducing device 30 is a sound reproducing device for reading out, reproducing, and outputting digital audio data recorded in an MD 1 and is provided with a piezoelectric speaker 17 as a sound output means. The piezoelectric speaker 17 has; a cover-like speaker enclosure 2 which is provided with sound emission holes 3 in a principal surface 2a and has an end surface 2b in the open side opposed to the principal surface, attached and fixed to an enclosure 19 of the portable MD reproducing device 20 by a fixing means K1; a diaphragm 7 which has a spacer 6 having a vibration absorbing property, arranged in an outer peripheral part 5 thereof so that the outer peripheral part 5 is attached and fixed in the speaker enclosure 2 a prescribed gap apart from the principal surface 2a; a piezoelectric element 10 which has a thin film electrode formed on a principal surface thereof and is fixed to both surfaces of the diaphragm; and a connection means K2 for conductive connection from the thin film electrode 8 of the piezoelectric element 10 to an output circuit 21 in the enclosure 19. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention reads digital audio data recorded on a disc recording medium such as a compact disc (abbreviated as CD), mini disc (abbreviated as MD) or DVD audio. The present invention relates to a sound reproducing device that reproduces and outputs, and particularly relates to a sound output means of a portable sound reproducing device.

  Conventionally, portable sound reproducing devices (including a reproduction-only device and a recording / reproducing device) that reproduce CDs, MDs, and the like have been commercialized, but these portable sound reproducing devices have a small volume of the casing. In addition, since a battery is used as a drive source, it is difficult to incorporate a dynamic speaker in the housing, and a method of listening to reproduced / amplified sound exclusively with earphones or headphones as sound output means is employed.

  In addition, among the above portable sound reproducing devices, there is a type that can be used as a stationary CD / MD stereo component indoors by separately connecting an amplifier and a dynamic speaker to a provided external output terminal. is there.

  On the other hand, in various home appliances, piezoelectric speakers (mainly ferroelectric ceramics such as lead titanate zirconate (PZT)) are used as the vibration source for the loudspeakers that are widely used as notification buzzers for single to simple scales. Speaker).

  The piezoelectric speaker generally has a thin piezoelectric element made of a piezoelectric material having a thin film electrode formed by applying a silver paste or the like on the main surface, and is attached to the center of a thin disc-shaped brass plate having a diameter of about 20 mm. The piezoelectric element in which the lead wire is derived from the thin film electrode is housed in a speaker housing made of plastic or the like, and the thickness of the piezoelectric element is as thin as 1 mm or less, and is small, low power consumption, and low cost. Has characteristics. However, as a speaker of a sound reproducing apparatus for playing music, the frequency range in the audible range is poor and the output is small, so that the applicable range is limited to the buzzer of home appliances and the speaker of a telephone as described above. .

  Recently, taking advantage of the small size, thinness, low power consumption, and the like of the piezoelectric speaker, application as a speaker built in a desktop or laptop personal computer has begun.

  In this point, [Patent Document 1], a diaphragm of a piezoelectric speaker is directly attached to a flexible polymer housing (shell) of a computer or the like, and the housing itself is mechanically vibrated together with the diaphragm. A technique is described in which a piezoelectric speaker having a configuration that emits sound is used as sound output means.

Japanese translation of PCT publication No. 2002-507849

  Recently, the frequency characteristics of the piezoelectric speaker have been improved, so that it can be applied as a speaker for simple sound output means in a sound reproducing apparatus.

  In a portable sound reproduction device that reads, reproduces, and outputs digital audio data recorded on a disk recording medium such as a CD, MD, or DVD audio, a built-in speaker as sound output means other than earphones and headphones Although there is no doubt that it is convenient for the user when confirming the reproduction of the disk recording medium, it is possible to prevent the optical pickup unit that is the reading means of the disk recording medium from being vibrated as much as possible during reproduction. Especially important.

  In this regard, if a dynamic speaker is mounted on the housing of a small portable sound reproduction device, there is a problem because the vibration of the speaker is transmitted from the housing to the optical pickup, and as described above, the occupied volume of the speaker and the power consumption It was also difficult to adopt.

  Further, the technique of actively transmitting the vibration of the piezoelectric speaker of the above-mentioned [Patent Document 1] to the housing to vibrate the housing itself and using it as a speaker is used for a relatively large electronic device such as a laptop computer. However, it cannot be adopted from the viewpoint of avoiding the influence of vibration for a small portable sound reproducing apparatus that reproduces and outputs a disk recording medium.

  The present invention has been made in view of the above circumstances, and in particular, as a sound output means in a portable sound reproduction device that reads, reproduces, and outputs digital audio data recorded on a disk recording medium, a piezoelectric type It is an object of the present invention to provide a sound reproducing device including a speaker.

  In order to achieve the above object, the present invention is an acoustic reproduction apparatus 30 that reads out and reproduces digital audio data recorded on a disk recording medium 1 and outputs it from a piezoelectric speaker 17 attached to a housing 19. The piezoelectric speaker 17 has a sound emitting hole 3 on the main surface 2a, and an open end surface 2b facing the main surface 2a is bonded and fixed to the housing 19 of the sound reproducing device 30 by fixing means K1. A lid-like speaker housing 2, a diaphragm 7 whose outer peripheral portion 5 is bonded and fixed to the inside of the speaker housing 2 through a spacer 6 having vibration absorption characteristics, separated from the main surface 2a, and a thin film electrode 8. Is formed on the main surface and is fixed to one or both surfaces of the diaphragm 7. The piezoelectric element 10 is composed of the piezoelectric material 9, and the acoustic wave is transmitted from the thin film electrode 8 of the piezoelectric element 10. To provide an acoustic reproduction apparatus 30 which is a piezoelectric type speaker 17 having a connection means K2 conductively connected to the output circuit 21 in the housing 19 of the raw device 30.

Since the sound reproducing device according to the present invention is configured as described above,
(1) The vibration of the diaphragm of the piezoelectric speaker is absorbed by the spacer interposed between the housing of the sound reproducing device and the housing of the speaker and is not directly transmitted to the housing of the sound reproducing device, but the optical pickup portion of the disk recording medium Therefore, stable reproduction without sound skipping can be achieved.
(2) A portable sound reproducing apparatus that reads, reproduces, and outputs digital audio data recorded on a disk recording medium incorporating a speaker as sound output means with little increase in size is realized.

  The best mode of the sound reproducing apparatus according to the present invention will be described with reference to the drawings, taking a portable MD reproducing apparatus to be applied as an example.

  FIG. 1 is a schematic cross-sectional view for explaining a structure in which a piezoelectric speaker of a portable MD reproducing apparatus according to the present invention is attached. FIG. 2 is an enlarged schematic cross-sectional view for explaining the mounting structure of the piezoelectric speaker according to the present invention. FIG. 3 is a perspective view showing an example of the appearance of the portable MD playback apparatus according to the present invention.

  1, 2, or 3, the portable MD playback device 30 according to the present invention reads, plays, and outputs digital audio data recorded on a disk recording medium (MD) 1 with an optical pickup unit P. In particular, the sound reproducing device is provided with a sound emitting hole 3 on the main surface 2a and an open end surface 2b facing the main surface 2a is bonded to the housing 19 of the portable MD reproducing device 30 by a fixing means K1. A fixed lid-like speaker housing 2, and a diaphragm 7 that is bonded and fixed to the inside of the speaker housing 2 by a predetermined distance from the main surface 2 a via a spacer 6 whose outer peripheral portion 5 has vibration absorption characteristics; The thin film electrode 8 is formed on the main surface and the piezoelectric element 10 made of the piezoelectric material 9 fixed to both surfaces (or one surface) of the diaphragm 7 and the thin film electrode 8 of the piezoelectric element 10 to the mobile phone. And connecting means K2 conductively connected to the output circuit 21 in the housing 19 of the MD reproducing apparatus 30, a piezoelectric type speaker 17 having, characterized in that it comprises a sound output means.

  In this portable MD playback device 30, the diaphragm 7 to which the piezoelectric element 10 is fixed is not directly attached to the housing 19 of the portable MD playback device 30, but the speaker housing 2 is provided with a spacer 6 having vibration absorption characteristics. Since the speaker housing 2 is mounted on the housing 19 of the portable MD playback device 30, the sound of the vibration / sound pressure is suppressed without directly transmitting the vibration of the piezoelectric speaker 17 to the optical pickup portion P. A playback device is realized. Hereinafter, each member will be described.

  The speaker housing 2 is made of plastic or metal such as aluminum and has a thin lid-like shell having a height of about 2 to 3 mm. As shown in FIG. 3, the housing 19 of the portable MD playback device 30 is used. It is being fixed to the outer surface of this by the fixing means K1. The fixing means K1 is, for example, a double-sided adhesive tape or a synthetic resin adhesive having a strong adhesive force.

  The spacer 6 has a thickness of 0.5 to 1.5 mm, a width of about 2 mm, and a ring shape that matches the diameter of the diaphragm 7, is made of a so-called sponge-like porous rubber, and has vibration absorption characteristics. . The spacer 6 has a thickness that is necessary and sufficient to secure a vibration space of the diaphragm 7 by separating the moving plate 7 and the casing 19 from each other by a predetermined distance and not to transmit vibration to the casing 19.

  The diaphragm 7 is a circular copper plate, phosphor bronze plate, stainless steel plate or aluminum plate having a diameter of 20 to 30 mm and a thickness of about 0.02 to 0.1 mm.

  The piezoelectric material 9 is a single piece or a laminated ceramic ceramic such as disc-shaped lead zirconate titanium zirconate (PZT), and the thin film electrode 8 is made of, for example, silver paste made of the piezoelectric material (single or laminated). Applied to each main surface). The piezoelectric element composed of the diaphragm 7 to which the piezoelectric element 10 is fixed is very thin with a thickness of about 0.7 mm in the case where the diaphragm 7 is a disk having a diameter of 23 mm.

  For example, as shown in FIG. 2, the connecting means K <b> 2 is configured such that each lead wire 14 led out from the thin film electrode 8 in the radial direction of the diaphragm 7 is connected to the terminal terminal 15, and the casing of the portable MD playback device 30 is connected. The terminal circuit 16 connected to the earphone 22 from the output circuit 21 in the terminal 19 is connected to the terminal terminal 16 through the output selector switch SW.

  In addition to the above structure, in the portable MD playback device 30 of FIGS. 1 and 2, a cover 12 made of metal such as aluminum or plastic is provided on the acoustic playback device side of the diaphragm 7, which is also The diaphragm 7 is disposed on the outer periphery of the diaphragm 7 at a predetermined distance via a spacer 6 ′ similar to the spacer 6.

  Although the cover 12 is provided with a sound emitting hole 13 in the center, it has the function of sound pressure adjusting means for preventing sound pressure due to vibration of the diaphragm 7 from being released directly to the sound reproducing device side. It is desirable to arrange them.

  Since the portable MD playback device 30 having the above structure incorporates a thin and small piezoelectric speaker 17 as an acoustic output means, the increase in cost and volume is a conventional product even though it is a product with high added value. It has a feature that there is almost no leakage magnetic flux which is a problem in a dynamic speaker.

  As a reminder, the above description is for a portable MD playback device, but other disk recording medium sound playback devices such as a portable CD playback device and a portable DVD audio playback device are also included in the present invention. Of course, it is within the range of the sound reproducing apparatus.

It is a schematic cross section of the sound reproducing device according to the present invention. It is an expanded sectional view which shows the attachment structure of the piezoelectric speaker in the sound reproduction apparatus which concerns on this invention. 1 is a perspective view of a portable MD playback device according to the present invention.

Explanation of symbols

1 Disc recording medium (MD)
2 Speaker housing 2a Main surface 2b Open side end surface 3, 13 Sound emitting hole 5 Outer peripheral portion of diaphragm 6, 6 'Spacer 7 Diaphragm 8 Thin film electrode 9 Piezoelectric material 10 Piezoelectric element 12 Cover 14 Lead wire 15, 16 Terminal terminal 17 Piezoelectric speaker 19 housing 21 output circuit 22 earphone 30 portable MD playback device K1 fixing means K2 connecting means SW output changeover switch

Claims (1)

A sound reproducing device that reads and reproduces digital audio data recorded on a disk recording medium, and outputs the digital audio data from a piezoelectric speaker attached to a housing,
The piezoelectric speaker has a sound emitting hole on the main surface, and an open end surface facing the main surface is bonded and fixed to the housing of the sound reproducing device by a fixing means, and an outer peripheral portion is A diaphragm that is bonded and fixed inside the speaker housing by a predetermined distance from the main surface via a spacer having vibration absorption characteristics, and a thin film electrode are formed on the main surface and are fixed to one or both surfaces of the diaphragm. A piezoelectric speaker comprising: a piezoelectric element made of a piezoelectric material formed; and a connection means for conductively connecting the thin film electrode of the piezoelectric element to an output circuit in the housing of the acoustic reproduction device. apparatus.

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