WO2005046067A1

WO2005046067A1 - Mobile telephone having speaker with waterproof structure

Info

Publication number: WO2005046067A1
Application number: PCT/KR2004/002820
Authority: WO
Inventors: Sang Choon Lee; Yong Chi
Original assignee: Watercom Co., Ltd.
Priority date: 2003-11-08
Filing date: 2004-11-04
Publication date: 2005-05-19
Also published as: KR100699248B1; KR20050044969A

Abstract

A mobile communication terminal having a waterproof speaker is disclosed. The terminal includes a voice coil (10) to which a voice current is applied. A magnet (20) generates a magnetic field by the voice current flowing through the voice coil, thus vibrating the voice coil. A cone paper (30) produces a sound wave due to variation of air pressure caused by vibration transmitted from the voice coil. A speaker frame (40) supports the cone paper 30, with an air circulation hole (42) formed on a rear wall of the speaker frame. A waterproof sheet (50) is watertightly attached to the rear wall of the speaker frame to cover a portion around the air circulation hole, and has a plurality of perforations (52) to communicate with the air circulation hole. Each perforation has a diameter of 0.05mm to 0.001 mm to allow air penetration and prevent water penetration.

Description

MOBILE TELEPHONE HAVING SPEAKER WITH WATERPROOF STRUCTURE

Technical Field The present invention relates, in general, to a mobile communication terminal having a waterproof speaker and, more particularly, to a mobile communication terminal having a waterproof speaker, which is capable of preventing water from flowing into an important portion of a speaker's structure, that is, a gap between a voice coil and a magnet, when the mobile communication terminal is exposed to water or the like, thus preventing loss of the speaker's function or rapidly restoring the speaker's function.

Background Art Generally, mobile communication terminals, for example, mobile phones and personal digital assistants (PDAs) enable people to make calls, regardless of their location. While a person carries a mobile communication terminal, the mobile communication terminal may be exposed to water by mistake. However, most of the current mobile communication terminals do not have waterproof structures. Hence, water may flow into parts of a circuit provided in an outer casing. The contact of the circuit parts with water causes the loss of the function of the circuit parts, so that a mobile communication terminal is likely to be damaged. In order to prevent the malfunction of the mobile communication terminal due to water and allow a person to carry and use the mobile communication terminal on a beach or in a public bathhouse, demand for a waterproof mobile communication terminal has increased. The mobile communication terminal having the waterproof structure isolates the circuit parts from water and moisture, thus preventing the circuit parts from contacting water. However, most conventional mobile communication terminals, such as mobile phones, have no waterproof structure. Thus, if a mobile phone is exposed to even a small amount of water, the mobile phone becomes out of order or damaged, so that the mobile phone malfunctions. Recently, mobile communication terminals having waterproof structures have been proposed. These mobile communication terminals are designed to seal gaps of outer casings. However, it is difficult to completely seal the gaps of the outer casing of each mobile communication terminal, so that a sufficient waterproof effect is not achieved. Further, in order to completely seal the gaps of the outer casing, the size of the mobile communication terminal is inevitably increased. Thus, manufacturers have many limitations on design of the mobile communication terminals. Additionally, high development costs and manufacturing costs of the mobile communication terminals are incurred, so that the mobile communication terminals are uneconomical and their marketability is poor. In order to solve the problems, there have been proposed Korean Patent Appln. No. 02- 53760 which was filed on Sep. 6, 2002 by the applicant of this invention, Korean U.M. Registration No. 0296276 which was filed as a utility model based on the Korean Patent Appln. No. 02-53760, and Korean Patent Appln. No. 03-60543 which takes priority from the Patent Appln. No. 02-53760 and was filed on Aug. 30, 2003. According to the cited documents, a mobile phone includes in its outer casing a built-in assembly having a portion to be made waterproof. In order to prevent water from flowing into a predetermined portion of the built-in assembly, a core frame is attached to the built-in assembly. Subsequently, the built-in assembly with the attached core frame is subjected to an insert molding process to be surrounded with a resin product made of elastomer. Alternatively, after a resin product that is made of a material, such as polycarbonate, through a vacuum molding process is coupled to the core frame, the built-in assembly may be surrounded by the core frame coupled to the resin product. This does not limit the design for the outer casing of the mobile phone, and does not remarkably increase manufacturing costs. Further, such a construction reliably prevents water or moisture from penetrating circuit parts of the built-in assembly, even when the mobile phone is exposed to water. However, in order to accomplish a waterproof structure for an entire portion of a mobile communication terminal, a waterproof structure for contact points, namely, a portion around a contact terminal and a speaker is required, in addition to the waterproof technology for the built-in assembly. Since the waterproof technology for the portion around the contact terminal and the speaker may be used apart from the above-mentioned waterproof technology, the waterproof technology itself has an important meaning. Thus, the waterproof structure for the speaker of the mobile communication terminal will be described below in detail. 5 The mobile communication terminal, such as a mobile phone and a PDA, is provided with two kinds of speakers or a combination-type speaker. One of the two speakers is used to output voice, while the other is used to output signal tone or sound. The combination-type speaker outputs both voice and various kinds of sounds. Generally, the speaker functions to transduce electric energy into mechanical energy using a voice coil provided in a gap, according

L0 to Fleming's left-hand law stating that a magnetic force is applied to a live conductor when the conductor is in a magnetic field. That is, when a current signal having several frequencies, namely, a voice signal, is applied to the voice coil, the voice coil generates mechanical energy depending on the intensity of current and the frequency. Further, a cone paper attached to the voice coil vibrates, thus generating sound pressure of a predetermined magnitude which can be

.5 heard by a person's ears. A magnetic circuit of the speaker is designed such that magnetic flux is interlinked wfth the voice coil provided in the gap at a right angle, using a magnet. The voice coil is adhered to the cone paper, and generates an excitation force in response to an input signal to vibrate the cone paper that is adhered to a speaker frame, thus generating sound pressure. In the speaker

!0 of the mobile communication terminal, an air circulation hole is formed on a rear wall of the speaker frame. Thereby, when the cone paper vibrates, air circulates from a space between the speaker frame and a rear surface of the cone paper to the outside, thus regulating mechanical strength. Further, a protector, that is, a front cover is mounted to the speaker frame to cover a front surface of the cone paper. A plurality of sound output holes is formed on the

!5 front cover, so that sound pressure generated by the cone paper is transmitted through the sound output holes to the outside. In the conventional mobile communication terminal, the cone paper is mounted to the speaker frame to close an opening of the speaker frame. Thus, although water flows into the terminal through the sound output holes provided on the protector, that is, the front cover of the speaker, the water cannot enter a portion behind the cone paper. Hence, by tilting the mobile communication terminal, water remaining in front of the cone paper is easily discharged to the 5 outside, and the function of the speaker can be rapidly restored. However, when water flows through the air circulation hole formed on the rear wall of the speaker frame into a narrow gap between the magnet and the voice coil, which are positioned behind the cone paper, it is difficult to remove the water and thus the water may undesirably remain in the narrow gap between the voice coil and the magnet. In this case, the voice coil is functionally disordered, thus causing the 10 malfunction of the speaker. Even ff the voice coil operates, several problems occur due to a water film. That is, variation in sound, reduction in sound volume, or reduction in frequency range occurs, so that the capability of the speaker is deteriorated.

Technical Solution Accordingly, the present invention has been made keeping in mind the above problems

L5 occurring in the prior art, and an object of the present invention is to provide a mobile communication terminal having a wateφroof speaker, which is capable of preventing water from flowing into an important portion of a speaker's structure, that is, a gap between a voice coil and a magnet, even when the mobile communication terminal is exposed to water or the like, thus ensuring a reliable water sealing effect, or rapidly restoring the speaker's function after the

' 0 speaker has temporary trouble.

Advantageous Effects According to the present invention, a mobile communication terminal having a wateφroof speaker is capable of preventing water from flowing into an important portion of a speaker's structure, that is, a gap between a voice coil and a magnet, even when the mobile

5 communication terminal is exposed to water or the like, thus ensuring a reliable water sealing effect, or rapidly restoring the speaker's function after the speaker has temporary trouble.

Description of Drawings FIG. 1 is a perspective view of a mobile phone having a wateφroof structure, according to an embodiment of the present invention; 5 FIG. 2 is a sectional view of a speaker of the mobile phone of FIG. 1 ; and FIG. 3 is a plan view of a wateφroof sheet of the mobile phone of FIG. 2.

Best Mode In order to accomplish the above object, the present invention provides a mobile communication terminal having a wateφroof speaker, including a voice coil to which a voice

10 current is applied; a magnet to generate a magnetic field by the voice current flowing through the voice coil, thus vibrating the voice coil; a cone paper to produce a sound wave due to variation of air pressure caused by vibration transmitted from the voice coil; a speaker frame to support the cone paper, with an air circulation hole formed on a rear wall of the speaker frame to circulate air existing between a rear surface of the cone paper and the speaker frame, when the cone paper

L5 vibrates; and a wateφroof sheet water-tightly attached to the rear wall of the speaker frame to cover the air circulation hole, and having a plurality of perforations to communicate with the air circulation hole, each of the perforations having a diameter of 0.05mm to 0.001mm to allow air penetration and prevent water penetration. The perforations of the wateφroof sheet may be made by a laser beam. ! 0 Preferably, the wateφroof sheet is made of polyester, and has a thickness of 0.1 mm to 0.2mm. Further, the wateφroof sheet is adhered to the speaker frame by a rubber coating using thermosetting rubber.

Mode for Invention This invention will be described in further detail by way of example with reference to the accompanying drawings. The present invention may be adapted to various mobile communication terminals, including mobile phones and personal digital assistants (PDAs). However, the mobile phone will be described herein as an example of the mobile communication terminals. FIG. 1 is a perspective view of a mobile phone having a wateφroof structure, according to an embodiment of the present invention. As shown in the drawing, the mobile phone 1 having the wateφroof structure includes a main body 5, a speaker 3, and a microphone 7. A plurality of signal input buttons 5a used to input data and a liquid crystal display (LCD) 5b are provided on the main body 5. The speaker 3 is mounted to the main body 5 to output a sound signal or a ring-back tone. The microphone 7 is provided on a predetermined portion of the main body 5 to input a voice signal. Further, a built-in assembly (not shown) having circuit parts is housed in the main body 5. FIG. 2 is a sectional view of the speaker of the mobile phone of FIG. 1. As shown in the drawing, the speaker 3 includes a voice coil 10, a magnet 20, a cone paper 30, a speaker frame 40, a wateφroof sheet 50, a front cover 60, and a cushion member 70. The voice coil 10 is coupled to a PCB 9 for a terminal of a built-in assembly, with a voice current being applied to the voice coil 10. The magnet 20 generates a magnetic field due to the voice current flowing through the voice coil 10, thus vibrating the voice coil 10. The cone paper 30 produces a sound wave due to variation of air pressure caused by the vibration of the voice coil 10. The speaker frame 40 accommodates the cone paper 30, the magnet 20, and the voice coil 10 therein. An air circulation hole 42 is provided on a rear wall 41 of the speaker frame 40 to circulate air existing between a rear surface of the cone paper 30 and the speaker frame 40, when the cone paper 30 vibrates. Further, the wateφroof sheet 50 is water-tightly attached to the rear wall 41 of the speaker frame 40 to cover a portion around the air circulation hole 42. A plurality of perforations 52 is provided on the wateφroof sheet 50 to communicate with the air circulation hole 42. The perforations 52 allow air penetration while preventing water penetration. The front cover 60 is mounted to the speaker frame 40 in front of the cone paper 30. The cushion member 70 is adhered to a front wall of the front cover 60. The voice coil 10 is electrically connected to the PCB 9 for the terminal, so that a voice electric signal is transmitted from the PCB 9 through a gold wire (not shown) to the voice coil 10. 5 A vibrating force is generated by the repulsion of the input electric energy. The voice coil 10 is fabricated by winding a coil formed by coating an insulation layer and a bonding layer on a conductor, such as copper or aluminum, around a bobbin made of paper, aluminum sheet, etc. The magnet 20 comprising a permanent magnet serves to move the voice coil 10 back and forth, according to Fleming's left-hand law. That is, the magnet 20 continuously supplies L 0 strong direct current flux to a magnetic circuit where an electromagnetic force acts on the speaker frame 40. The cone paper 30 is also known as a diaphragm. The vibration of the voice coil 10 is transmitted to the cone paper 30, thus resulting in variation of air pressure. This generates a sound wave having a predetermined magnitude which can be heard by a person's ears. .5 The speaker frame 40 is a component to define the size and shape of the speaker 3, and serves as a framework for the speaker 3, which supports the cone paper 30, the voice coil 10, the gold wire, and the magnet 20. Generally, the air circulation hole 42 is provided on the rear wall 41 of the speaker frame 40. When the cone paper 30 vibrates, some of the air existing between the rear surface of the voice coil 10 and the speaker frame 40 is pressurized, thus being 0 discharged to the outside through the air circulation hole 42. A plurality of sound output holes 62 is provided on the protector, that is, the front cover 60, and the front cover 60 is adhered to the front wall of the speaker frame 40 by a rubber coating. Further, the cushion member 70 is adhered to the front of the front cover 60, and serves 5 to absorb shocks transmitted from the main body 5, when the speaker 3 is coupled to the main body 5. FIG. 3 is a plan view of the wateφroof sheet of FIG. 2. As shown in the drawing, the wateφroof sheet 50 is attached to the rear wall 41 of the speaker frame 40 to cover a portion around the air circulation hole 42. The attachment of the wateφroof sheet 50 to the speaker frame 40 is achieved by a rubber coating using thermosetting rubber. The rubber coating is rather expensive, but is advantageous in that seamless attachment is allowed using the thermosetting rubber, so that excellent wateφroof effect and simple maintenance are accomplished. Thus, the rubber coating prevents water from flowing into a junction, or gap between the wateφroof sheet 50 and the speaker frame 40. The wateφroof sheet 50 is made of polyester and has a thickness from 0.1 mm to 0.2mm. A plurality of small perforations 52 is provided through a predetermined portion of the wateφroof sheet 50 to communicate with the air circulation hole 42. Since each perforation 52 has a diameter of 0.05mm to 0.001mm, air can pass through the perforation 52 but water cannot pass through the perforation 52. According to the embodiment, each perforation 52 has a diameter of about 0.03mm. The perforations 52 are formed using a predetermined pattern and are perforated by a laser beam. The number of areas having perforations 52 corresponds to the number of air circulation holes 42. The operation of the mobile communication terminal having the wateφroof structure, which is constructed as described above, will be described below. For example, when the mobile phone 1 is moistened by rain or falls into water, water may flow into the sound output holes 62 of the front cover 60. However, the cone paper 30 is attached to the speaker frame 40 to cover an entire section of the opening of the speaker frame 40, so that water cannot enter a portion behind the cone paper 30. Thus, water flowing into the speaker 3 through the sound output holes 62 does not enter the gap between the voice coil 10

- and the magnet 20 that are located behind the cone paper 30. Water existing between a front of the cone paper 30 and the speaker frame 40 can be easily discharged through the sound output holes 62 by tilting the mobile phone 1. Therefore, although the mobile phone 1 gets wet, the function of the speaker 3 is rapidly restored through a simple manipulation. Meanwhile, if water flows into the speaker frame 40 through the air circulation hole 42 provided on the rear wall 41 of the speaker frame 40, the speaker 3 malfunctions. However, according to the present invention, the wateφroof sheet 50 is water-tightly adhered to the rear wall 41 of the speaker frame 40 by the rubber coating to cover a portion around the air circulation hole 42. Further, a plurality of perforations 52, having a diameter that is set to allow air 5 penetration but prevent water penetration, is provided on a predetermined portion of the wateφroof sheet 50. Therefore, water cannot flow through the air circulation hole 42 into the speaker 3, especially, the gap between the voice coil 10 and the magnet 20. Such a construction prevents the speaker 3 from getting out of order, even though the mobile phone 1 is exposed to water or the like.

10 As described above, the present invention provides a mobile communication terminal, including the voice coil 10 to which a voice current is applied, the magnet 20 which generates a magnetic field due to the voice current flowing through the voice coil 10 to vibrate the voice coil 10, the cone paper which produces a sound wave due to variation of air pressure due to vibration transmitted from the voice coil 10, the speaker frame 40 which supports the cone paper 30, with

L 5 the air circulation hole 42 formed on the rear wall 41 of the speaker frame 40 to circulate air existing between the rear surface of the cone paper 30 and the speaker frame 40 when the cone paper 30 vibrates, and the wateφroof sheet 50 which is water-tightly attached to the rear wall 41 of the speaker frame to cover a portion around the air circulation hole 42, and has a plurality of perforations 52 to communicate with the air circulation hole 42, each of the perforations having a

: 0 diameter of 0.05mm to 0.001 mm to allow air penetration and prevent water penetration. Such a construction prevents water from flowing into an important portion in the speaker's function, that is, a gap between the voice coil 10 and the magnet 20, even when the mobile communication terminal is exposed to water or the like, thus ensuring a reliable water sealing effect, or rapidly restoring the speaker's function after the speaker 3 has temporary trouble.

5 According to this embodiment, the wateφroof sheet 50 is water-tightly attached to the rear wall 41 of the speaker frame 40 by a rubber coating using thermosetting rubber. However, various adhesives may be used, as long as the wateφroof sheet 50 is attached to the speaker frame 40.

Claims

CLAIMS [Claim 1] A mobile communication terminal having a wateφroof speaker, comprising: a voice coil to which a voice current is applied; 5 a magnet to generate a magnetic field by the voice current flowing through the voice coil, thus vibrating the voice coil; a cone paper to produce a sound wave due to variation of air pressure caused by vibration transmitted from the voice coil; a speaker frame to support the cone paper, with an air circulation hole formed on a rear L0 wall of the speaker frame to circulate air existing between a rear surface of the cone paper and the speaker frame, when the cone paper vibrates; and a wateφroof sheet water-tightly attached to the rear wall of the speaker frame to cover the air circulation hole, and having a plurality of perforations to communicate with the air circulation hole, each of the perforations having a diameter of 0.05mm to 0.001mm to allow air .5 penetration and prevent water penetration.

[Claim 2] The mobile communication terminal according to claim 1 , wherein the perforations of the wateφroof sheet are made by a laser beam.

[Claim 3] 0 The mobile communication terminal according to claim 1 , wherein the wateφroof sheet is made of polyester, and has a thickness of 0.1 mm to 0.2mm.

[Claim 4] The mobile communication terminal according to claim 1, wherein the wateφroof sheet is adhered to the speaker frame by a rubber coating using thermosetting rubber.