JP2003348201A - Electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure for improving the electrostatic resistance of an electronic apparatus, which is suited to miniaturization and unnecessitates the work for improving the electrostatic resistance at the time of assembling the electronic apparatus. <P>SOLUTION: A shielding member arranged between an electronic circuit stored in a casing and the casing is provided with a supporting member for supporting an acoustic element and having a conductive part electrically connected to the earth of the electronic circuit, the acoustic element provided with a conductive cover on a surface from which sound waves are radiated is arranged between the shielding member and the casing, a buffer member for elastically holding the acoustic element is arranged between the acoustic element and the casing, and the conductive part is formed on the side of the buffer member which is opposed to the acoustic element to electrically connect the supporting member to the conductive cover through the conductive part. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small electronic device such as a portable telephone, and more particularly to a structure suitable for preventing a trouble caused by static electricity.

[0002]

2. Description of the Related Art As a measure for preventing malfunction of electronic equipment due to static electricity, it is common practice to form a conductive film on the inner surface of a housing case so that an internal electronic circuit is not electromagnetically coupled to the outside. However, in an electronic device having an acoustic element (a transmitter, a receiver, and a speaker (for generating a ringtone)) such as a mobile phone, a portion of the housing facing the receiver, the transmitter, and the speaker transmits sound waves. It is necessary to have an opening, and it cannot be separated electromagnetically only by the housing. A vibrating plate and electrodes are provided inside a cylindrical aluminum case with one end closed, and a conductive sheet such as a metal fiber sheet or a sintered metal sheet is provided on the opening surface so that electrical contacts can be formed. Japanese Patent Laid-Open No. 11-1274
No. 98.

[0003]

In the above prior art, the outer peripheral portion of the acoustic element is formed of metal, and it is easy to obtain an electrical connection for grounding. However, when this technology is applied to a ring tone speaker of a mobile phone (hereinafter, the speaker refers to a ring tone speaker unless otherwise specified), a positioning portion for mounting to a housing is formed to assemble the device at the time of assembly. In order to improve workability or reduce the weight, it is necessary to mold the exterior part with plastic.

[0004] However, when plastic is used, a grounding component must be attached to improve the electrostatic withstand capability of the speaker, which causes a problem that the number of operations increases and the manufacturing cost increases.

An object of the present invention is to provide an electronic device which is small in size and excellent in workability during assembly.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a housing having an opening for allowing sound waves to pass therethrough, an electronic circuit stored in the housing, and an electronic device. A shield member interposed between the circuit and the housing, an acoustic element disposed between the shield member and the housing, and an elastic element interposed between the acoustic element and the housing to elastically hold the acoustic element And a support member having a conductive part electrically connected to the ground of the electronic circuit, the acoustic element having a conductive member on a surface that emits sound waves. With a conductive cover, the conductive cover is supported by a support member so as to face the housing, the cushioning member has a conductive portion on the side facing the acoustic element,
The support member and the conductive cover are electrically connected by the conductive portion.

[0007]

1 to 5 show an embodiment of the present invention.
This will be described with reference to FIG. The present embodiment describes a case where the electronic device is a portable electronic device, particularly a mobile phone. Electronic devices, such as mobile phones, are small and lightweight for convenience in carrying, but they are easy to operate, easy to view, high quality, and multifunctional. I have.

An outline of the present embodiment will be described with reference to FIGS. The mobile phone housing is on the front side (front case)
And a rear surface (rear case), and it is general that important points are fastened with two to four screws. In addition to the circuit board on which the electronic circuit is mounted, an antenna, a liquid crystal display, a receiver or transmitter as an acoustic element, a key switch, a battery, a connector, a vibrator, and the like are attached to the housing. With the development of small electronic components and high-density multilayer boards, main circuits are mounted on one circuit board. It is common practice to mount a shield case as a shield member on a circuit board and surround the high frequency circuit inside the housing to prevent high frequency electromagnetic interference with the inside and outside of the telephone. In order to improve the sound quality of the ringtone, a mobile phone generally provided with a speaker having a larger diameter than the receiver as an acoustic element in addition to the receiver, and a shield case is provided as a ringtone speaker (hereinafter, unless otherwise specified, The speaker plays a role of supporting and fixing the ring tone speaker). The housing case has an opening for allowing sound waves radiated from the speaker to pass therethrough, and has a conductive film formed on an inner surface thereof so that an internal electronic circuit and the outside are not electromagnetically coupled. Therefore, in the electrostatic withstand voltage test, in order to prevent malfunction of the circuit due to the inflow of static electricity from the speaker opening, a metal cover having a conductive air permeability on the front surface of the speaker, that is, a surface emitting sound waves. And measures such as connecting the metal cover to the ground of the electronic circuit have been implemented. Further, the metal cover is also used for protection when the speaker element is used alone. The exterior part of the speaker is made of plastic to provide a positioning function and to reduce the weight.

The speaker is disposed on one of the shield cases and is positioned by a support provided on the shield case, and the tip of the support is located relatively close to the metal cover of the speaker. In addition, a dust-proof net for preventing dust from entering through an opening of the housing facing the speaker is disposed between the housing and the speaker, and a ring-shaped cushion is provided on the outer periphery of the dust-proof net as a cushioning member. Have been. In the assembled state, the cushion is compressed in the thickness direction between the inner surface of the housing and the speaker, and the reaction force presses the speaker toward the shield case, so that even if a shock is applied to the mobile phone, the speaker remains inside the housing. There are no jumps. The positional relationship between these components is as shown in FIGS.

In order to improve the electrostatic withstand strength of such a speaker, as shown in FIG. 6, a countermeasure in which both ends of a copper foil provided with a thin adhesive layer are attached to the metal cover and the shield case of the speaker in the process leading to the present invention. Was considered. Since the adhesive layer is thin, static electricity flows between the copper foil having a low resistance and the metal cover, so that it is possible to prevent a failure through another electronic circuit. However, it is necessary to attach a copper foil to a predetermined portion at the time of assembling a mobile phone, and the improvement of workability at the time of assembling cannot be solved.

Hereinafter, the present embodiment will be described in detail with reference to FIGS. 1 and 2 show the configuration of main components of a mobile phone. In the following description, those with an A after the numeral indicate that they are subassemblies. The direction is based on the designation shown in FIG. In addition, even if there are a plurality of similar parts, the reference numerals (numbers) indicating the respective parts show only one representative place in most cases.

A high frequency circuit is formed on the upper front surface 301 and the rear surface 302 of the circuit board assembly 3A,
Low frequency and control circuits are formed at 3 and the lower rear 304. A transmitter assembly 6A is fixed to the lower front end of the circuit board assembly 3A, and a connector assembly 10A is fixed to the lower rear end of the circuit board assembly 3A. A vibrator assembly 11A is fixed near the center of the rear surface. The front shield case 3 covering the LSI is located above the front of the circuit board assembly 3A.
2 are arranged. A receiver 5A is attached to the upper front of the front shield case 32, and a liquid crystal display assembly 4A is attached to the remaining front. On the other hand, a rear shield case 33 is disposed above the rear surface side of the circuit board assembly 3A, also covering the LSI. In the present embodiment, as shown in FIG. 5, the rear shield case is provided with a large number of openings 33H for reducing the weight on the surface. The arrangement and number of the openings are determined experimentally by measuring the shielding effect. A speaker assembly 9A is attached to the rear side of the rear shield case 33. Circuit board assembly 3
A key shield case 34 is disposed on the lower front surface of A. A switch sheet (not shown) is arranged in front of the key shield case 34, and a key sheet (not shown) is arranged in front of the switch sheet. The key sheet has a plurality of key buttons arranged on the molded rubber sheet, and functions as a key switch in pairs with a switch sheet provided with corresponding contacts and wiring. The above-mentioned components are sandwiched from both sides by a front case 11 in which a transparent plastic plate 12 for protecting a liquid crystal display portion is fixed to an upper window, and a rear case 21 containing an antenna assembly 7A. Rear case 21
An opening for voice passage facing the ring tone melody speaker assembly 9A is provided above, and a battery chamber 23 for storing batteries is provided below. Battery compartment 23 is covered by battery compartment cover 8. Front shield case 3
2. The rear shield case 33 and the key shield case 34 are plastic molded products, and their surfaces are chemically nickel-plated for electromagnetic shielding. Circuit board assembly 3A
As described above, a front shield case 32 and a rear shield case 33 are attached from both sides to the front and rear surfaces as described above, and a liquid crystal display assembly 4A and a speaker assembly 9A are respectively stacked.

The front case 11 and the rear case 21 are 4
The screws are joined to the nine screws by nine fitting engagement portions (a method in which a first member provided with a convex portion at the tip is pushed and coupled to a second member having a corresponding concave portion by utilizing elasticity). The screw joints are the four corners at the center and the lower end in the height direction.

In order to prevent unnecessary radiation of high frequency radio waves, the front shield case 32 and the like must be electrically connected to the ground of the circuit board assembly 3A. And is electrically connected to the ground of the circuit board assembly 3A in the assembled state.

FIG. 3 shows a sectional shape of the rear shield case 33.
It is shown in (c). The cross section of FIG. 3 and FIG.
A section. In the rear shield case 33, a plurality of walls 332 stand from the top plate 331, and a part of the outer peripheral wall sandwiches the substrate 31 of the circuit board assembly 3A, and presses the rear shield case 33 onto the substrate 31 to attach it. Are provided. On the upper surface of the top plate 331, three speaker support portions 334 for sandwiching and supporting the speaker assembly 9A are provided as support members. The tip 335 of the speaker support portion 334 is curved inward, and after pushing in the speaker assembly 9A, the speaker assembly 9A is pressed.
Is a stopper so that it does not pop out. The rear shield case 33 is nickel-plated on plastic as described above, and the entire surface is conductive. That is,
The surface of the speaker support 334 including the tip 335 is conductive, and is electrically connected to the ground of the substrate 31.

FIG. 3 shows a sectional shape of the speaker assembly 9A.
It is shown in (b). The speaker assembly 9A is a moving coil type. A stainless steel cover 92 having a plurality of ventilation holes is fixed on the front surface of the speaker section 91 of the speaker assembly 9A. Below the speaker section 91, two metal leaf springs 9 connected to the lead wires of the moving coil are provided.
3 is fixed. These leaf springs, as shown in FIG. 4, come into contact with the lands of the flexible substrate 35 attached to the upper surface of the rear shield case 33 and are connected to the drive circuit.

A dustproof net assembly 22A is attached to the inner surface of the rear case 21 facing the speaker assembly 9A by a ring-shaped double-sided adhesive sheet attached to the upper surface. Dust-proof net as a buffer 2
FIG. 3A shows a cross-sectional shape of 2A. Dustproof net 223
A ring-shaped cushion 222 as a cushioning material is
Is bonded, and a ring-shaped copper foil 221 is bonded below the cushion 222 as a conductive portion. In the present embodiment, the cushion 222 is a porous (sponge-like) and insulating elastic body. Copper foil 221 and cushion 222
Is manufactured in a sheet shape with a double-sided pressure-sensitive adhesive sheet adhered to the surface of the cushion 222 on the dust-proof net side, and is formed by punching the sheet into a ring shape. A dustproof net assembly 22A in which a ring-shaped cushion 222 with copper foil and a double-sided adhesive sheet 224 for attachment are attached to both surfaces of the dustproof net 223.
Are prepared as subassemblies.

FIG. 4 shows a state in which the above components are assembled. FIG. 4 shows a partial cross section of only the rear side from the substrate 31. As shown in FIG. 4, the ring-shaped portion of the dustproof net assembly 22A is connected to the inner surface of the rear case 21 and the speaker assembly 9A.
The copper foil 221 is greatly deformed by being sandwiched between A and the support tip 335, and the elasticity of the cushion 222 presses the copper foil 221 against the cover 92 and the support tip 335 of the speaker assembly 9A. The pressing force of the cushion 222 is set large so that the speaker assembly 9A does not rattle, and there is no fear that the electrical connection between the cover 92 and the support portion distal end 335 is separated. Further, since the copper foil 221 has a ring shape, even if the plurality of support portions 334 are only partially present around the circular speaker assembly 9A, the speaker assembly 9A is not required.
The electrical connection can be achieved only by making the center of the ring-shaped copper foil 221 substantially coincide with the center of the copper foil 221. A circular shallow depression is provided in the speaker facing portion on the inner surface of the rear case 21. By fitting the recess into the recess, the dustproof net assembly 22A can be easily positioned and attached with a double-sided adhesive sheet.

In the present embodiment, the copper foil 221 is bonded to the cushion 222. Alternatively, the copper foil 221 may be omitted by making the cushion 221 itself conductive. In this case, conductive fibers such as metal fibers or conductive powder of carbon or metal may be mixed into the cushion 222,
Alternatively, the cushion 222 may be formed of conductive fibers,
Furthermore, it is possible to make it conductive by forming it with a conductive elastic body such as conductive rubber or conductive sponge.

In the present embodiment, the dustproof net assembly 22A is attached to the rear case 21 with an adhesive sheet before assembling. However, the present invention is not limited to this. The work can be performed only by pushing the dustproof net assembly 22A into the cylindrical space provided inside the body.

The conductive portion does not necessarily have to be ring-shaped, but may be partially provided in accordance with the position of the support portion 334.

In this embodiment, by attaching the copper foil 221 to one surface of the cushion 222 or changing the material of the cushion 222, the electrostatic shield of the speaker opening can be performed without increasing the work at the time of assembly. . Therefore, electrostatic shielding can be performed with almost no increase in cost.

The present invention is not limited to the above-described embodiment, but is included in the present invention as long as it has the same function even if it has a different shape or structure from this specification or the drawings. It is what is done.

[0024]

According to the present invention, it is possible to obtain a compact electronic device having excellent workability at the time of assembly.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an electronic device according to an embodiment of the present invention, as viewed obliquely from the upper right front of the electronic device.

FIG. 2 is an exploded perspective view of a board and a rear case of the electronic device according to the embodiment of the present invention, as viewed obliquely from the upper rear right side.

FIG. 3 is a cross-sectional view individually showing components related to electrostatic strength around a speaker of the electronic apparatus according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view of the vicinity of the speaker when assembling the electronic device according to the embodiment of the present invention.

FIG. 5 is an exemplary front view showing the rear shield case of the electronic device and the assembled state of the speaker according to the embodiment of the present invention;

FIG. 6 is a front view showing an assembled state of the shield case and the speaker after being studied in the process leading to the present invention.

[Explanation of symbols]

3A: Circuit board assembly, 8: Battery compartment cover, 9A: Speaker assembly, 11: Front case, 21: Rear case, 22A: Dustproof net assembly 31: Board, 32: Front shield case, 33: Rear shield case, 34: Key Shield case, 35: Flexible board, 36: Copper foil with adhesive, 91: Speaker, 9
2: Metal cover with holes 93: Lead leaf spring, 221: Copper foil, 222: Cushion, 223: Dustproof net, 224: Double-sided adhesive sheet, 3
31: shield case top plate, 332: shield case wall, 333: shield case claw, 334: support portion, 33
5: Support part tip.

Claims (4)

[Claims] 1. A housing provided with an opening for allowing sound waves to pass therethrough, an electronic circuit stored in the housing, a shield member interposed between the electronic circuit and the housing, and the shield An acoustic element disposed between the member and the housing;
In an electronic device including a buffer member interposed between the acoustic element and the housing to elastically retain the acoustic element, the shield member holds the acoustic element and grounds the electronic circuit. A support member having a conductive portion electrically connected to the acoustic element; the acoustic element includes a conductive cover on a surface emitting the sound wave; and the conductive cover is supported by the support member such that the conductive cover faces the housing. Wherein the buffer member has a conductive portion on a side facing the acoustic element, and the conductive portion electrically connects the support member and the conductive cover. machine. 2. The electronic apparatus according to claim 1, wherein said conductive portion is a sheet-like metal disposed on a surface of said buffer member. 3. The electronic device according to claim 1, wherein said conductive portion is a fibrous metal contained in said buffer member. 4. The electronic device according to claim 1, wherein said buffer member is formed of a conductive elastic body.