WO2007148869A1

WO2007148869A1 - Manufacturing method of slim type microspeaker

Info

Publication number: WO2007148869A1
Application number: PCT/KR2007/001329
Authority: WO
Inventors: Juyeon Kim
Original assignee: Bluecom Co., Ltd.
Priority date: 2006-06-23
Filing date: 2007-03-19
Publication date: 2007-12-27
Also published as: KR100696367B1

Abstract

Disclosed herein is a method of manufacturing a slim type microspeaker. The slim type microspeaker uses both an oval P-type magnet and an oval F-type magnet, thus minimizing the thickness of the microspeaker, and increases precision of manufacture of the oval F-type magnet and an oval voice coil. A bonding agent overflow prevention groove and a bonding agent receiving groove are formed in the bottom of a plate and the top of a yoke, respectively, thus preventing bond leaking from between the yoke, the oval P-type magnet, and the plate from entering vibration space of the voice coil when the oval P-type magnet and the plate are sequentially bonded to the yoke, thus securing space for the stable vibration of the voice coil.

Description

[DESCRIPTION]

[invention Title]

MANUFACTURING METHOD OF SLIM TYPE MICROSPEAKER

[Technical Field]

The present invention relates, in general, to a method of manufacturing a slim type microspeaker. More particularly, the present invention relates to a method of manufacturing a slim type microspeaker, which uses both an oval P-type magnet and an oval F-type magnet, thus minimizing the thickness of the microspeaker, increases the precision of manufacture of the oval F-type magnet and an oval voice coil, and prevents a bonding agent, leaking from between a yoke, the oval P-type magnet, and a plate, from entering the vibration space of the voice coil when the oval P-type magnet and the plate are sequentially bonded to the yoke, thus securing space for the stable vibration of the voice coil.

[Background Art] Sound which can be heard by a person's auditory sense, is transmitted in the form of waves. The sound having the wave form moves air molecules and vibrates the tympanic membrane, thus allowing a person to hear the sound. In order to provide audible sounds, various kinds of speakers have been developed. The speaker is a sound producing apparatus that outputs electrically or electronically received audio signals or a previously input bell or melody in the form of sound that can be heard by a person. The speaker is generally coupled to audio equipment or an amplifier for use as a large sound producing means for considerably amplifying volume. Alternatively, the speaker may be used as a small sound producing means having a small size and volume.

As such, the small-sized speaker may be mounted to a small electronic product, such as a mobile phone, a PDA, or a notebook computer. As the wireless age begins, consumers want to consume various content regardless of time and place and demand portability. In order to satisfy the consumers' desires, speakers are tending towards miniaturization and lightness.

A speaker, which is mounted to an electronic product that is miniaturized and light, that is, a microspeaker, is disclosed in Korean U.M. Registration No. 20-220353, which is entitled "Small Speaker Structure' and Korean Patent No. 10- 432615, which is entitled 'Oval Speaker' . The microspeaker disclosed in the cited documents includes a stationary magnetic circuit having one magnet and a movable magnetic circuit having a coil that is wound circularly.

However, there is a limit to the amount of sound that can be generated by vibrating a diaphragm using one magnet and the coil paired with the magnet. Thus, although a microspeaker having a smaller volume is required for various kinds of small electronic products, it is impossible to reduce the microspeaker below a predetermined size.

[Disclosure] [Technical Problem]

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a method of manufacturing a slim type microspeaker, in which an oval P-type magnet and an associated plate and an oval F-type magnet and an associated plate are placed on a yoke, thus forming a stationary magnetic circuit corresponding to a driving magnetic circuit of a voice coil, therefore minimizing the thickness of the microspeaker having the oval P-type magnet and the associated plate and the oval F-type magnet and the associated plate.

Another object of the present invention is to provide a method of manufacturing a slim type microspeaker, which increases the precision of an oval F-type magnet and a voice coil during the manufacture of the oval F-type magnet and the voice coil, thus obtaining stable output.

A further object of the present invention is to provide a method of manufacturing a slim type microspeaker, which automates the process of applying bonding agent to a diaphragm when a voice coil is attached to the diaphragm, thus simplifying the assembly process of the microspeaker, and allowing a proper amount of bonding agent to be applied at the correct position.

Yet another object of the present invention is to provide a method of manufacturing a slim type microspeaker, in which a bonding agent overflow prevention groove is formed in the outer portion of the bottom of a plate attached to an oval P-type magnet, and a bonding agent receiving groove is formed in a yoke to which the oval P-type magnet is attached, thus preventing bonding agent, leaking from between the yoke and the oval P-type magnet and from between the oval P-type magnet and the plate, from entering the space in which a voice coil vibrates .

[Technical Solution]

In order to accomplish the objects, the present invention provides a method of manufacturing a slim type microspeaker, in which a stationary magnetic circuit is formed by integrating a yoke, at least one magnet, and at least one plate with a frame, and in which a movable magnetic circuit plate is formed in such a way as to correspond to the stationary magnetic circuit formed by the yoke, the magnet, and the plate by attaching a diaphragm to the frame, and arranging a voice coil provided on a lower portion of the diaphragm to be near to the yoke, the magnet, and the plate, wherein the magnet comprises an oval F- type magnet or an oval F-type magnet and an oval P-type magnet, a method of manufacturing the oval F-type magnet including a first step of cutting a magnet material into a shape of a rectangular rod; a second step of longitudinally cutting an outer circumference of a magnet having the shape of the rectangular rod into an oval shape, and longitudinally forming an oval hole in a center of the magnet having the shape of the rectangular rod; a third step of cutting a magnet having the shape of an oval rod in a direction orthogonal to a longitudinal direction of the magnet, thus manufacturing an oval F-type magnet; a fourth step of grinding upper and lower surfaces of the oval F-type magnet obtained at the third step; a fifth step of removing sharp corners of an oval F-type magnet, obtained at the fourth step, using a barrel polisher; and a sixth step of sequentially plating a surface of the oval F-type magnet with copper and zinc, and drying the oval F-type magnet.

Preferably, the outer circumference and the hole of the magnet having the shape of the rectangular rod are formed to have an oval shape through wire cutting. Preferably, after a surface of the oval F-type magnet is plated with zinc to be flattened, the flattened oval F-type magnet is sequentially plated with copper and zinc.

When a worker checks all oval F-type magnets which have been manufactured through cutting, grinding, and plating processes and it is determined that an oval F-type magnet is unsuitable, the method further includes a step of repeating the processes, thus increasing precision of the oval F-type magnet.

In order to accomplish the objects, the present invention provides a method of manufacturing a slim type microspeaker, in which a stationary magnetic circuit is formed by integrating a yoke, at least one magnet, and at least one plate with a frame, and in which a movable magnetic circuit plate is formed in such a way as to correspond to the stationary magnetic circuit formed by the yoke, the magnet, and the plate by attaching a diaphragm to the frame, and arranging a voice coil provided on a lower portion of the diaphragm to be near to the yoke, the magnet, and the plate, wherein the voice coil is a voice coil wound in an oval shape, and the oval voice coil is manufactured by winding a coil around an oval coil chuck of an oval coil winding machine .

The method further includes a step of flattening a linear part of the oval voice coil by striking the linear part of the voice coil, which is wound ovally by the oval coil chuck of the oval coil winding machine, using a flat surface of a striking tool .

In order to accomplish the objects, the present invention provides a method of manufacturing a slim type microspeaker, in which a stationary magnetic circuit is formed by integrating a yoke, at least one magnet, and at least one plate with a frame, and in which a movable magnetic circuit plate is formed in such a way as to correspond to the stationary magnetic circuit formed by the yoke, the magnet, and the plate by attaching a diaphragm to the frame, and arranging a voice coil provided on a lower portion of the diaphragm to be near to the yoke, the magnet, and the plate, wherein the voice coil is a voice coil wound in an oval shape, and the oval voice coil is formed to have two linear parts by winding the coil around a circular coil chuck of a circular coil winding machine, fitting the circularly wound voice coil over a pair of guides of an oval coiling machine, and moving a movable guide.

Preferably, the oval coiling machine simultaneously forms a plurality of circularly wound voice coils into oval voice coils .

In order to accomplish the objects, the present invention provides a method of manufacturing a slim type microspeaker, in which a stationary magnetic circuit is formed by integrating a yoke, at least one magnet, and at least one plate with a frame, and in which a movable magnetic circuit plate is formed in such a way as to correspond to the stationary magnetic circuit formed by the yoke, the magnet, and the plate by attaching a diaphragm to the frame, and arranging a voice coil provided on a lower portion of the diaphragm to be near to the yoke, the magnet, and the plate, wherein the diaphragm and the voice coil are attached to each other through a bonding process, the process of bonding the diaphragm to the voice coil including a first step of placing a plurality of diaphragms on a support frame, and seating the support frame on a holder of a bonding agent applicator; a second step of moving the holder of the bonding agent applicator forwards and backwards, and moving bonding agent supplying units of the bonding agent applicator vertically and horizontally, thus applying bonding agent to a surface of each of the diaphragms to which the voice coil is attached; and a third step of attaching the voice coil to the surface of each of the diaphragms to which the bonding agent is applied.

Preferably, the support frame of the bonding agent applicator and the bonding agent supplying units of the bonding agent applicator simultaneously support the plurality of diaphragms, and simultaneously apply the bonding agent to the plurality of diaphragms supported by the support frame of the bonding agent applicator.

In order to accomplish the objects, the present invention provides a method of manufacturing a slim type microspeaker, in which a stationary magnetic circuit is formed by integrating a yoke, at least one magnet, and at least one plate with a frame, and in which a movable magnetic circuit plate is formed in such a way as to correspond to the stationary magnetic circuit formed by the yoke, the magnet, and the plate by attaching a diaphragm to the frame, and arranging a voice coil provided on a lower portion of the diaphragm to be near to the yoke, the magnet, and the plate, wherein the magnet and the plate comprise an oval F-type magnet and a plate, and an oval P-type magnet and a plate, the oval F-type magnet and the plate being integrated with the frame, together with the yoke, the oval P- type magnet and the plate are sequentially attached to a central portion of the yoke, and a bonding agent overflow prevention groove is formed in an outer portion of a lower surface of the plate attached to the oval P-type magnet, thus preventing bonding agent, applied between the oval P-type magnet and the plate, from leaking out therebetween, when the plate is attached to an upper portion of the oval P-type magnet.

Preferably, a sectional area of a portion of the plate, positioned inside the bonding agent overflow groove, is equal to 75 to 95% of an entire sectional area of the plate. In order to accomplish the objects, the present invention provides a method of manufacturing a slim type microspeaker, in which a stationary magnetic circuit is formed by integrating a yoke, at least one magnet, and at least one plate with a frame, and in which a movable magnetic circuit plate is formed in such a way as to correspond to the stationary magnetic circuit formed by the yoke, the magnet, and the plate by attaching a diaphragm to the frame, and arranging a voice coil provided on a lower portion of the diaphragm to be near to the yoke, the magnet, and the plate, wherein the magnet and the plate comprise an oval F-type magnet and a plate, and an oval P-type magnet and a plate, the oval F-type magnet and the plate are integrated with the frame, together with the yoke, and the oval P-type magnet and the plate are sequentially attached to a central portion of the yoke, and a bonding agent receiving groove is formed in a portion of the yoke that meets an outer circumference of the oval P-type magnet, so that bonding agent applied between the yoke and the oval P-type magnet flows from between the yoke and the oval P-type magnet when the oval P- type magnet is attached to the yoke, and fills the bonding agent receiving groove, thus enhancing adhesive strength.

Preferably, a portion of the yoke, which is positioned inside the bonding agent receiving groove and corresponds to 75 to 95% of a sectional area of the yoke, contacts the oval P- type magnet, and the bonding agent receiving groove is arranged such that part of the bonding agent receiving groove overlaps a lower end of the outer circumference of the oval P-type magnet.

[Advantageous Effects]

As described above, according to the present invention, an oval P-type magnet and an associated plate and an oval F-type magnet and an associated plate are placed on a yoke, thus forming a stationary magnetic circuit corresponding to a driving magnetic circuit of a voice coil, therefore minimizing the thickness of a microspeaker having the oval P-type magnet and the associated plate and the oval F-type magnet and the associated plate.

Further, the present invention increases the precision of an oval F-type magnet and a voice coil during the manufacture of the oval F-type magnet and the voice coil, thus providing stable output to a slim type microspeaker.

The present invention automates the process of applying bonding agent to a diaphragm when a voice coil is attached to the diaphragm, thus simplifying the assembly process of a microspeaker, and allowing a proper amount of bonding agent to be applied at the correct position.

Further, according to the present invention, a bonding agent overflow prevention groove is formed in the outer portion of the bottom of a plate attached to an oval P-type magnet, and a bonding agent receiving groove is formed in a yoke to which the oval P-type magnet is attached, thus preventing bonding agent, leaking from between the yoke and the oval P-type magnet and from between the oval P-type magnet and the plate, from entering the space in which a voice coil vibrates.

[Description of Drawings]

FIG. 1 is a perspective view showing a slim type microspeaker, according to the present invention;

FIG. 2 is a bottom view of the slim type microspeaker, according to the present invention; FIG. 3 is an exploded perspective view of the slim type microspeaker, according to the present invention;

FIGS. 4 to 6 are sectional views showing the slim type microspeaker, according to the present invention;

FIGS. 7 to 9 are views illustrating the process of manufacturing an oval F-type magnet;

FIG. 10 is a sectional view showing the process of mounting an oval P-type magnet and a plate on the central portion of a yoke which is integrated with the oval F-type magnet and a frame, according to the present invention; FIGS. 11 to 13 are views showing an oval coiling machine for forming a circularly wound voice coil into an oval voice coil, according to the present invention;

FIG. 14 is a perspective view showing important parts of an oval coil winding machine for winding the oval voice coil; FIG. 15 is a view showing the process of correcting linear parts of the oval coil by striking the ovally wound coil;

FIG. 16 is a view showing a bonding agent applicator for applying bonding agent to a diaphragm so as to attach the voice coil to the diaphragm; and FIG. 17 is a graph representing output characteristics that are obtained from a conventional circular microspeaker and the slim type microspeaker according to the present invention. -Description of reference characters of important parts- 10: frame 11: lead wires 12, 12a: non-woven fabric 13: holes 14 : cap 15 : connection pad

16: yoke 17, 23: air holes

18a: oval F-type magnet 18b: oval P-type magnet

19a, 19b: plate 20: locking protrusions 21: voice coil 22: diaphragm

24: movable plate 25: stationary plate

26: movable guide 27: stationary guide

28: actuating switch 29: cylinder

30: actuating rod 31: frame 32 : guide 33 : guide groove 34 : bonding agent overflow prevention groove 35: bonding agent receiving groove

36a, 36b, 36c : bonding agent 37: oval coiling machine

38: oval coil winding machine 39: oval coil chuck

40 coil 41: linear part

42 curved part 43 : striking tool

44 bonding agent applicator 45: support frame

46: holder 47: bonding agent supplying unit 48: control box 49: button

[Best Mode]

The present invention will be described in detail below. As shown in FIG. 1, most of the parts of the slim type microspeaker according to the present invention, including a frame 10, have oval horizontal sections. A cap 14 is coupled to the top of the frame 10 to protect parts installed in the frame. A plurality of holes 13 is formed in the cap 14 so that air flows through the holes. Further, a filter, such as a piece of non-woven fabric 12, is attached to the top of the cap 14, and prevents various impurities from entering the microspeaker along with the air.

Further, as shown in FIG. 2, a plurality of connection pads 15 is provided at a predetermined position on the bottom of the frame 10. Two lead wires 11 are electrically connected to the connection pad 15, and supply voice current to both ends of a voice coil and the voice coil. A plurality of air holes 23 is vertically formed through the frame 10, and allows air to smoothly flow through the interior and exterior of the microspeaker. A non-woven fabric 12a is attached to the bottom of the frame 10 to cover the air holes 23. Similar to the non- woven fabric 12 which is provided on the top of the cap 14, the non-woven fabric 12a functions to prevent various impurities from entering the microspeaker along with the air.

A plurality of air holes 17 is vertically formed through a yoke 16 which is integrated with the frame 10 in such a way as to be positioned at the center of the frame 10. Unlike the air holes 23, the air holes 17 are used as a path for discharging air remaining between the yoke 16 and an oval P-type magnet and excessively applied bonding agent to the outside, when the oval P-type magnet is attached to the upper portion of the yoke 16. The construction and the method of manufacturing the slim type microspeaker according to this invention, the oval P-type magnet 18b, an oval F-type magnet 18a, plates 19b and 19a, the voice coil 21, a diaphragm 22, and other parts constituting the microspeaker will be described with reference to FIGS. 3 to 6.

First, the frame 10, formed using an insulating material which may be freely formed, such as a plastic, is integrated with the oval yoke 16, the oval F-type magnet 18a, and the plate 19a. Especially, in the state where the yoke 16, the oval F-type magnet 18a, and the plate 19a are put into a mold, they are formed integrally with the frame 10. Thus, the precision of assembly of the microspeaker is increased, and the manufacturing process of the microspeaker is simplified.

The process of manufacturing the oval F-type magnet 18a is as follows. As shown in FIG. 7, a magnet material 18c is cut into a magnet 18d having the shape of a rectangular rod. As shown in FIG. 8, the outer portion of the magnet 18d having the shape of the rectangular rod is longitudinally cut to have an oval shape. Further, an oval hole is formed in the central portion of the magnet in the lengthwise direction thereof using a wire cutter. Thereby, a magnet 18e having the shape of an oval rod is obtained.

At this time, in order to bore the oval hole in the center of the magnet 18d having the shape of the rectangular rod, a hole 18f is bored in the lengthwise direction of the magnet 19d having the shape of the rectangular rod, using a tool such as a drill . Subsequently, the wire cutter is put into the hole to form the oval hole in the center of the magnet 18d having the shape of the rectangular rod. After the magnet 18e having the shape of the oval rod has been manufactured as such, the magnet 18e having the shape of the oval rod is cut using a cutter in a direction which is orthogonal to the lengthwise direction of the magnet, as shown in FIGS. 7 to 9. Thereby, the oval F-type magnet 18g is obtained.

Since the surface of the oval F-type magnet 18g, which is cut by various kinds of cutters, is uneven, the upper and lower surfaces of the oval F-type magnet 18g are ground using a surface grinder. Further, sharp corners of the oval F-type magnet 18g are removed using a barrel polisher.

The final process of manufacturing the oval F-type magnet 18a is executed as follows. The surface of the oval F-type magnet 18g is sequentially plated with copper and zinc (or nickel) , and is then dried, so that the oval F-type magnet 18a is completed. Before the surface of the oval F-type magnet is plated with copper and zinc, the surface of the oval F-type magnet 18g is thinly plated with zinc or nickel so that the surface of the oval F-type magnet 18g is flattened.

After the oval F-type magnet 18a is manufactured through the above process, all of the oval F-type magnets 18a, which have been manufactured through cutting, grinding, and plating processes, are checked so as to lower the defect rate of the oval F-type magnet 18a and the slim type microspeaker equipped therewith. If it is determined that the oval F-type magnet is unsuitable, the processes are repeated, thus increasing the precision of the oval F-type magnet. Thereby, the F-type magnet 18a is manufactured to match initial design dimensions.

Hereinbefore, only the manufacturing process of the oval F-type magnet 18a has been described. The manufacturing process is identically applied to the oval P-type magnet 18b, except that the shape of the oval P-type magnet 18b is formed.

Locking protrusions 20 each having a predetermined height are provided on the outer edge of the upper portion of the frame 10 which has the oval horizontal section, and function to couple the diaphragm 22 and the cap 14 with the frame. The air holes 23 are vertically formed inside the locking protrusions 20, and make the interior of the microspeaker communicate with the exterior thereof. The air holes 23 are holes for permitting the smooth flow of air between the interior of the microspeaker and the exterior thereof.

As described above, the filter, such as the non-woven fabric 12a, is attached to the bottom of the frame 10, and prevents various impurities from entering the microspeaker through the air holes 23. The connection pad 15 is attached to a predetermined position on the bottom of the frame 10. The lead wires 11 are electrically connected (soldered) to the connection pad 15 so as to electrically connect both ends of the voice coil 21 to the exterior.

The oval P-type magnet 18b and the plate 19b are attached to the yoke 16, which is integrated with the frame 10, the oval F-type magnet 18a, and the plate 19a, using bonding agent 36a and 36b. In order to maintain the interval between the oval F- type magnet 18a and the oval P-type magnet 18b, a guide 25 having a width the same as the interval between the F-type magnet 18a and the P-type magnet 18b, which must be maintained when the manufacture of the microspeaker has been completed, is provided on the inside surfaces of the F-type magnet 18a and the plate 19a, which are integrated with the frame 10. As shown in FIG. 10, the oval P-type magnet 18b and the plate 19b are placed inside the guide 25, and are pressed by a pressure rod 24, so that the oval P-type magnet 18b and the plate 19b are attached to the upper portion of the yoke 16.

That is, before the P-type magnet 18b and the plate 19b are attached to the yoke, as shown in FIG. 10, an adhesive, such as the bonding agent 36b, is applied to the yoke 16 using a general method, that is, by applying a bonding agent with a brush or spraying a bonding agent using gas pressure. The guide 25 is placed on the yoke 16 coated with the bonding agent 36b in such a way as to contact the inside surfaces of the oval F-type magnet 18a and plate 19a. After the oval P-type magnet 18b and the plate 19b are attached to each other using the bonding agent 36a and are placed inside the guide 25, the oval P-type magnet and the plate are pressed by the pressure rod 24 so that the oval P-type magnet 18b is attached to the upper surface of the yoke 16. Such a method makes it easy to assemble the microspeaker, in addition to keeping the interval between the oval F-type magnet 18a and the oval P-type magnet 18b constant.

Of course, in place of attaching the oval P-type magnet 18b and the plate 19b, which have been attached to each other previously, to the yoke 16, a different assembly method may be used. That is, after the guide 25 is set up on the yoke 16, the oval P-type magnet 18b and the plate 19b may be sequentially attached while the bonding agent 36a and 36b is applied.

Moreover, the present invention may attach the oval P-type magnet and the plate in various methods without using the guide 25, as long as the oval P-type magnet 18b and the plate 19b are installed at precise positions. In this case, the inner width of the guide 25 is set such that the upper portion thereof is wider than the lower portion thereof. Such a construction allows the oval P-type magnet 18b and the plate 19b, which are integrally attached to each other, to be easily put into the guide 25. In order to form one stationary magnetic circuit, the oval F-type magnet 18a and the oval P-type magnet 18b are magnetized to have different polarities on upper and lower portions thereof. Thus, compared to the magnetic field which is formed using one P-type magnet or F-type magnet, the stationary magnetic circuit, which is thinner and forms a stronger magnetic field, is formed by the oval F-type magnet 18a, the plate 19a, the plate 19b, the oval P-type magnet 18b, and the yoke 16.

Particularly, an undercut, that is, a bonding agent overflow prevention groove 34, is formed on the outer portion of the bottom of the plate 19b which is attached to the upper portion of the oval P-type magnet 18b. When pressure acts on the oval P-type magnet 18b and the plate 19b so that the plate 19b is attached to the upper portion of the oval P-type magnet 18b, the bonding agent 36a, applied between the oval P-type magnet 18b and the plate 19b, spreads into the space between the oval P-type magnet 18b and the plate 19b.

Meanwhile, when an excessive amount of bonding agent 36a is applied between the oval P-type magnet 18b and the plate 19b, an excessive amount of bonding agent 36a may leak out between the oval P-type magnet 18b and the plate 19b, and may thus enter the space in which the voice coil 21 is located. However, according to the present invention, any excess bonding agent flows into the bonding agent overflow prevention groove 34, so that the bonding agent does not enter the space in which the voice coil 21 is located.

In this case, the position of the bonding agent overflow prevention groove 34 is set such that the sectional area of the plate 19b inside the bonding agent overflow prevention groove 34 is equal to 75 to 95% of the entire sectional area of the plate 19b. This ensures space for attaching the plate 19b to the oval P-type magnet 18b, in addition to ensuring space for forming the bonding agent overflow prevention groove 34 so as to prevent the bonding agent 36a from leaking out from the space between the oval P-type magnet 18b and the plate 19b.

Further, an undercut, that is, a bonding agent receiving groove 35, is formed at a position in the yoke 16 that meets the outer circumference of the oval P-type magnet 18b. When the oval P-type magnet 18b is attached to the upper portion of the yoke 16, some 36c of the bonding agent 36b applied between the yoke 16 and the oval P-type magnet 18b flows out between the yoke 16 and the oval P-type magnet 18b, and enters the bonding agent receiving groove 35 while being hardened therein. Thereby, the edge of the lower end of the oval P-type magnet 18b is firmly coupled to the yoke 16, so that the adhesive strength between the yoke 16 and the oval P-type magnet 18b can be increased.

Similarly to the bonding agent overflow prevention groove 34, preferably, the position of the bonding agent receiving groove is set such that 75 to 95% of the sectional area of the yoke 16 contacts the oval P-type magnet 18b, and part of the bonding agent receiving groove 35 overlaps the lower end of the outer circumference of the oval P-type magnet 18b.

The oval diaphragm 22 is locked to the locking protrusions 20 which are provided on the outer edge of the frame 10. The voice coil 21, which is wound in an oval form, is attached to the bottom of the diaphragm 22. After the voice coil 21 is wound in a circular form using a circular coil winding machine, the voice coil is formed to have an oval shape using an oval coiling machine, as shown in FIGS. 11 to 13. Alternatively, the voice coil may be formed to have an oval shape using an oval coil winding machine of FIG. 14.

FIGS. 11 to 13 show the oval coiling machine 37 for forming the voice coil, which is wound in the circular form, into the oval voice coil. First, actuating switches 28 mounted on a frame 31 are maneuvered, thus actuating cylinders 29 and actuating rods 30 which are operated in conjunction with the cylinders. Thereby, guides 32 of movable plates 24 move along guide grooves 33 of stationary plates 25, so that movable guides 26 come into contact with stationary guides 27.

Further, after the circularly wound voice coil is fitted between the movable and stationary guides 26 and 27, each actuating switch 28 is maneuvered again, so that the cylinder 29 and the actuating rod 30, operated in conjunction with the cylinder, are operated. The guides 32 of each movable plate 24 move along the guide grooves 33 of the corresponding stationary- plate 25 in a direction opposite the moving direction described above. Thereby, the movable guide 26 becomes spaced apart from the stationary guides 27 by a predetermined interval, so that the circular voice coil can be formed into the oval voice coil .

That is, thanks to the oval coiling machine 37, the part of the voice coil that contacts circular parts of the movable and stationary guides 26 and 27 forms the curved parts of the oval voice coil . The part of the voice coil that is positioned on the side surfaces of the movable and stationary guides 26 and 27 and positioned in the space between the movable and stationary guides 26 and 27 forms the linear parts of the oval voice coil .

As described above, a worker manipulates each actuating switch 28 to move the cylinder 29, the movable plate 24 operated in conjunction with the cylinder, and the movable guide 26. However, the present invention may use a solenoid valve as a driving source for moving the movable plate 24, or a worker himself may manually move the movable plate, without being limited to the above operating method.

FIGS. 14 and 15 illustrate the oval coil winding machine 38 for winding a coil 40 in an oval form, and the process of correcting the linear parts of the oval voice coil which is wound by the oval coil winding machine. First, the coil 40 is wound around an oval coil chuck 39 of the oval coil winding machine 38. The linear parts 41 of the ovally wound voice coil, that is, the parts (shown by the dotted lines) of the voice coil which may bulge, are struck by the flat surface of a striking tool 43. Thereby, the linear parts 41 of the oval voice coil are flattened, while the curved parts 42 of the oval voice coil maintain the curved state. Of course, the oval voice coil which is wound around the oval coil chuck 39 of the oval coil winding machine 38 may be used without going through the flattening process. However, in order to increase precision, as described above, the linear parts of the voice coil are flattened.

FIG. 16 shows a bonding agent applicator 44 which is used to apply bonding agent to the diaphragm 22 in order to attach the voice coil 21 to the diaphragm 22. The process of applying the bonding agent to the diaphragm 22 using the bonding agent applicator 44 of FIG. 16 in order to attach the voice coil 21 to the diaphragm 22 will be described below.

First, a plurality of diaphragms 22 is placed on a support frame 45 which is removably coupled to the bonding agent applicator 44, and the support frame is seated on a holder 46 of the bonding agent applicator 44. Subsequently, a driving source of the bonding agent applicator 44, which is not shown in the drawing, such as a servo motor, moves the holder 46 forwards and backwards, and moves bonding agent supplying units 47 of the bonding agent applicator 44 vertically and horizontally, so that bonding agent is applied to the surface of each diaphragm 22 to which the voice coil is adhered.

Next, a worker attaches the voice coil to the surface of each diaphragm 22, to which a bonding agent is applied.

Here, control boxes 48, which are provided on the upper portion of the bonding agent applicator 44, control the amount of air to be supplied to respective bonding agent supplying units 47, thus controlling the amount of bonding agent that is applied to respective diaphragms 22. A plurality of buttons 49 is provided on the front of the lower portion of the bonding agent applicator 44, and sets the operation mode of the bonding agent applicator 44.

As described above, after the diaphragm 22 having the voice coil 21 is attached to the frame 10, the frame is covered with the cap 14 so as to protect the internal components. Particularly, the non-woven fabric 12 is attached to the top of the cap 14, thus preventing various impurities from entering the microspeaker through the holes 13 of the cap 14. FIG. 17 represents the output characteristics that are obtained using a conventional circular microspeaker and using the slim type microspeaker according to the present invention. As described above, the slim type microspeaker of this invention can be dramatically reduced in thickness, and in addition, has output characteristics in an audio frequency band, that is, IKHz to 5KHz, superior to those of the conventional circular microspeaker.

[industrial Applicability] As described above, a slim type microspeaker of the present invention has a minimized thickness and a high output, thus being easy to mount in electronic products which are becoming smaller and smaller and more integrated, such as a mobile phone, a PDA, or a notebook computer, and satisfying the desire of consumers pursuing high-quality sound.

Claims

[CLAIMS]

[Claim l]

A method of manufacturing a slim type microspeaker, in which a stationary magnetic circuit is formed by integrating a yoke, at least one magnet, and at least one plate with a frame, and in which a movable magnetic circuit plate is formed in such a way as to correspond to the stationary magnetic circuit formed by the yoke, the magnet, and the plate by attaching a diaphragm to the frame, and arranging a voice coil provided on a lower portion of the diaphragm to be near to the yoke, the magnet, and the plate, wherein the magnet comprises an oval F-type magnet or an oval F- type magnet and an oval P-type magnet, a method of manufacturing the oval F-type magnet comprising: a first step of cutting a magnet material into a shape of a rectangular rod; a second step of longitudinally cutting an outer circumference of a magnet having the shape of the rectangular rod into an oval shape, and longitudinally forming an oval hole in a center of the magnet having the shape of the rectangular rod; a third step of cutting a magnet having an oval outer circumference in a direction orthogonal to a longitudinal direction of the magnet, thus manufacturing an oval F-type magnet ; a fourth step of grinding upper and lower surfaces of the oval F-type magnet obtained at the third step; a fifth step of removing sharp corners of an oval F-type magnet, obtained at the fourth step, using a barrel polisher; and a sixth step of sequentially plating a surface of the oval F-type magnet with copper and zinc, and drying the oval F-type magnet .

[Claim 2]

The method according to claim 1, wherein the outer circumference and the hole of the magnet having the shape of the rectangular rod are formed to have an oval shape through wire cutting.

[Claim 3l

The method according to claim 1, wherein a surface of the oval F-type magnet is plated with zinc to be flattened, and thereafter the flattened oval F-type magnet is sequentially plated with copper and zinc .

[Claim 4]

The method according to claim 1, further comprising: when a worker checks all oval F-type magnets which have been manufactured through cutting, grinding, and plating processes and it is determined that an oval F-type magnet is unsuitable, a step of repeating the processes, thus increasing precision of the oval F-type magnet.

[Claim 5]

A method of manufacturing a slim type microspeaker, in which a stationary magnetic circuit is formed by integrating a yoke, at least one magnet, and at least one plate with a frame, and in which a movable magnetic circuit plate is formed in such a way as to correspond to the stationary magnetic circuit formed by the yoke, the magnet, and the plate by attaching a diaphragm to the frame, and arranging a voice coil provided on a lower portion of the diaphragm to be near to the yoke, the magnet, and the plate, wherein the voice coil is a voice coil wound in an oval shape, and the oval voice coil is manufactured by winding a coil around an oval coil chuck of an oval coil winding machine.

[Claim 6] The method according to claim 5, further comprising: a step of flattening a linear part of the oval voice coil by striking the linear part of the voice coil, which is wound ovally by the oval coil chuck of the oval coil winding machine, using a flat surface of a striking tool . [Claim 7]

A method of manufacturing a slim type microspeaker, in which a stationary magnetic circuit is formed by integrating a yoke, at least one magnet, and at least one plate with a frame, and in which a movable magnetic circuit plate is formed in such a way as to correspond to the stationary magnetic circuit formed by the yoke, the magnet, and the plate by attaching a diaphragm to the frame, and arranging a voice coil provided on a lower portion of the diaphragm to be near to the yoke, the magnet, and the plate, wherein the voice coil is a voice coil wound in an oval shape, and the oval voice coil is formed to have two linear parts by winding the coil around a circular coil chuck of a circular coil winding machine, fitting the circularly wound voice coil over a pair of guides of an oval coiling machine, and moving a movable guide.

[Claim 8]

The method according to claim 7, wherein the oval coiling machine simultaneously forms a plurality of circularly wound voice coils into oval voice coils.

[Claim 9]

A method of manufacturing a slim type microspeaker, in which a stationary magnetic circuit is formed by integrating a yoke, at least one magnet, and at least one plate with a frame, and in which a movable magnetic circuit plate is formed in such a way as to correspond to the stationary magnetic circuit formed by the yoke, the magnet, and the plate by attaching a diaphragm to the frame, and arranging a voice coil provided on a lower portion of the diaphragm to be near to the yoke, the magnet, and the plate, wherein the diaphragm and the voice coil are attached to each other through a bonding process, the process of bonding the diaphragm to the voice coil comprising: a first step of placing a plurality of diaphragms on a support frame, and seating the support frame on a holder of a bonding agent applicator; a second step of moving the holder of the bonding agent applicator forwards and backwards, and moving bonding agent supplying units of the bonding agent applicator vertically and horizontally, thus applying bonding agent to a surface of each of the diaphragms to which the voice coil is attached; and a third step of attaching the voice coil to the surface of each of the diaphragms to which the bonding agent is applied.

[Claim lθ]

The method according to claim 9, wherein the support frame of the bonding agent applicator and the bonding agent supplying units of the bonding agent applicator simultaneously support the plurality of diaphragms, and simultaneously apply the bonding agent to the plurality of diaphragms supported by the support frame of the bonding agent applicator.

[Claim 111

A method of manufacturing a slim type microspeaker, in which a stationary magnetic circuit is formed by integrating a yoke, at least one magnet, and at least one plate with a frame, and in which a movable magnetic circuit plate is formed in such a way as to correspond to the stationary magnetic circuit formed by the yoke, the magnet, and the plate by attaching a diaphragm to the frame, and arranging a voice coil provided on a lower portion of the diaphragm to be near to the yoke, the magnet, and the plate, wherein the magnet and the plate comprise an oval F-type magnet and a plate, and an oval P-type magnet and a plate, the oval F- type magnet and the plate being integrated with the frame, together with the yoke, the oval P-type magnet and the plate are sequentially attached to a central portion of the yoke, and a bonding agent overflow prevention groove is formed in an outer portion of a lower surface of the plate attached to the oval P-type magnet, thus preventing bonding agent, applied between the oval P-type magnet and the plate, from leaking out therebetween, when the plate is attached to an upper portion of the oval P-type magnet.

[Claim 12]

The method according to claim 11, wherein a sectional area of a portion of the plate, positioned inside the bonding agent overflow groove, is equal to 75 to 95% of an entire sectional area of the plate.

[Claim 13] A method of manufacturing a slim type microspeaker, in which a stationary magnetic circuit is formed by integrating a yoke, at least one magnet, and at least one plate with a frame, and in which a movable magnetic circuit plate is formed in such a way as to correspond to the stationary magnetic circuit formed by the yoke, the magnet, and the plate by attaching a diaphragm to the frame, and arranging a voice coil provided on a lower portion of the diaphragm to be near to the yoke, the magnet, and the plate, wherein the magnet and the plate comprise an oval F-type magnet and a plate, and an oval P-type magnet and a plate, the oval F-type magnet and the plate are integrated with the frame, together with the yoke, and the oval P-type magnet and the plate are sequentially attached to a central portion of the yoke, and a bonding agent receiving groove is formed in a portion of the yoke that meets an outer circumference of the oval P-type magnet, so that bonding agent applied between the yoke and the oval P-type magnet flows from between the yoke and the oval P- type magnet when the oval P-type magnet is attached to the yoke, and fills the bonding agent receiving groove, thus enhancing adhesive strength.

[Claim 14]

The method according to claim 13, wherein a portion of the yoke, positioned inside the bonding agent receiving groove and corresponding to 75 to 95% of a sectional area of the yoke, contacts the oval P-type magnet, and the bonding agent receiving groove is arranged such that part of the bonding agent receiving groove overlaps a lower end of the outer circumference of the oval P-type magnet .