WO2007119988A1

WO2007119988A1 - Portable electronic device having sliding driving means using electromagnetic force

Info

Publication number: WO2007119988A1
Application number: PCT/KR2007/001822
Authority: WO
Inventors: Han Yong Cho; Jang Woo Lee
Original assignee: Hitech Parts Co., Ltd.
Priority date: 2006-04-14
Filing date: 2007-04-14
Publication date: 2007-10-25
Also published as: KR100722836B1

Abstract

The present invention relates to a sliding driving means using an electromagnetic force and an electronic device having the sliding driving means. More particularly, the present invention relates to a portable electronic device having a compact driving means capable of causing a display unit of the portable electronic device to be slid with respect to a main body of the portable electronic device by using a flat coil and a pair of electromagnets. A portable electronic device of the present invention comprises a main body having an upper surface provided with an input means for use in inputting information; a display unit installed to be slidable in a direction over the upper surface of the main body and provided with a display means for displaying information provided by the main body; and a driving means having a flat coil wound in a rectangular shape such that spacing of windings is smaller at one side and spacing of windings is larger at the other side along the sliding direction of the display unit on an identical plane, and a pair of permanent magnets spaced apart by a predetermined distance from each other such that different polarities thereof face each other in a state where the plane on which the flat coil is wound is interposed between the permanent magnets. The flat coil and the permanent magnets are installed between the main body and the display unit such that the display unit can be slid with respect to the main body by means of an electromagnetic force generated when a current flows through the flat coil.

Description

SLIDING DRIVING MEANS USING ELECTROMAGNETIC FORCE AND ELECTRONIC DEVICE HAVING THE SLIDING

DRIVING MEANS Technical Field

[1] The present invention relates to a sliding driving means using an electromagnetic force and an electronic device having the sliding driving means. More particularly, the present invention relates to a sliding driving means using a coil wound on a plane and a pair of electromagnets, and an electronic device having the sliding driving means. The sliding driving means of the present invention is useful since it enables a portable electronic device such as a mobile phone to be manufactured compactly. Background Art

[2] See Korean Patent Laid-Open Publication No. 10-2005-0100840 published on

October 20, 2005 and entitled "Slide type mobile phone automatically openable and closable by means of electromagnetic force" (hereinafter, referred to as 'Prior Art 1').

[3] A portable electronic device such as a mobile phone is manufactured to be light, thin, simple and small so that it can be conveniently carried with a user. However, even though an electronic device is intended to be miniaturized, it is necessary to enlarge a display for user's convenience. Therefore, in recent years, upon manufacture of an electronic device, a display unit with a display such as an LCD installed therein is constructed to be slid over an upper surface of a main body with input buttons provided therein, thereby allowing a larger display to be installed in the electronic device.

[4] Fig. 11 is a schematic view illustrating "Slide type mobile phone automatically openable and closable by means of electromagnetic force" disclosed in Cited Prior Art 1. Referring to Fig. 11, a display unit 120 with a display installed therein is constructed to be slid with respect to a main body 110. As shown in the figure, a plurality of permanent magnets are installed on an upper surface of the main body 110, and a plurality of coils 140 are installed on a lower surface of the display unit 120 that faces the upper surface of the main body 110. Reference numeral 150 designates a control unit for controlling a current supplied to the plurality of coils 140. The plurality of permanent magnets 130 are arranged such that different polarities are adjacent to each other, and the control unit 150 causes power to be sequentially supplied to the coils 140 so that attractive forces and repulsive forces are sequentially generated between the permanent magnets and the coils, resulting in a sliding motion of the display unit 120 with respect to the main body. [5] Since the mobile phone including a driving means using a linear motor constructed as above has the plurality of coils arranged in a direction perpendicular to the permanent magnets, there are problems in that the structure thereof is complicated and thus it is difficult to manufacture the mobile phone. Further, there are problems in that costs increase due to a lot of parts and the control for generating a thrust by causing a current to flow into the coils is complicated.

[6] Meanwhile, according to a theory of electromagnetics, in a case where a current flows through a wire arranged perpendicularly to the direction of a magnetic field, the direction of a force acting on the wire is determined pursuant to the Fleming's left-hand rule. In this case, according to the law of action and reaction, a permanent magnet may be fixed and the wire may serve as a movable member, or the wire may be fixed and the permanent magnet may serve as a movable member. Further, if a coil is wound such that the directions of currents flowing through windings of the coil within a magnetic field are identical to one another, a resultant force of electromagnetic forces acting on the respective windings of the coil acts on the entire coil, thereby representing a larger force. That is, if a coil wound such that the directions of currents flowing though windings of the coil are identical to one another is placed within a magnetic field created by a pair of electromagnets and a current is caused to flow through the coil, it is possible to provide a sliding driving means that has a simple structure and is slimmed. Moreover, in the case where the coil wound such that the directions of currents flowing though windings of the coil are identical to one another is placed within the magnetic field created by the pair of electromagnets, it is also possible to provide a sliding driving means of which control for generating a thrust is simplified.

Disclosure of Invention Technical Problem

[7] An object of the present invention is to provide a sliding driving means, wherein a coil wound such that the directions of currents flowing though windings of the coil are identical to one another is placed between a pair of permanent magnets, thereby enabling manufacture of a slimmed electronic device. Further, another object of the present invention is to provide an electronic device having a sliding driving means that has a simple structure and can be controlled conveniently. Particularly, an object of the present invention is to provide a portable electronic device having a display unit installed to be slidable with respect to a main body, wherein the display unit can be automatically slid due to provision of a sliding driving means. Technical Solution

[8] The present invention will be described by way of example in connection with a mobile phone as a portable electronic device. However, the present invention is not limited thereto but includes all electronic devices each of which has a main body with input buttons installed on an upper surface and a display unit capable of opening or closing the upper surface of the main body through sliding. For example, a PDA, an electronic dictionary, a notebook computer or the like having a slidable display unit falls within the scope of the portable electronic device of the present invention. In the present invention, the use of a sliding driving means is not limited only to the portable electronic device but can be applied to all devices in which a sliding motion is required between predetermined two positions.

[9] A portable electronic device of the present invention comprises a main body having an upper surface provided with an input means for use in inputting information; a display unit installed to be slidable in a direction over the upper surface of the main body and provided with a display means for displaying information provided by the main body; and a driving means having a flat coil wound in a rectangular shape such that spacing of windings is smaller at one side and spacing of windings is larger at the other side along the sliding direction of the display unit on an identical plane, and a pair of permanent magnets spaced apart by a predetermined distance from each other such that different polarities thereof face each other in a state where the plane on which the flat coil is wound is interposed between the permanent magnets, wherein the flat coil and the permanent magnets are installed between the main body and the display unit such that the display unit can be slid with respect to the main body by means of an electromagnetic force generated when a current flows through the flat coil.

[10] According to the present invention, there is provided a sliding driving means for a portable electronic device, wherein a flat coil wound such that spacing of windings is smaller (to be dense) at one side and spacing of windings is larger (to be sparse) at the other side on an identical plane is placed between a pair of permanent magnets arranged such that different polarities thereof face each other. If the flat coil wound on an identical plane is used as a fixed member or movable member, it is possible to construct a sliding driving means having a height that is the sum of a height corresponding to the thickness of the flat coil and the heights of the permanent magnets. Thus, it is possible to provide a slim type electronic device having a small thickness as a whole. Further, a sliding speed can be easily controlled only by adjusting the amount of a current flowing through the flat coil.

[11] Moreover, in the present invention, it is preferred that the flat coil of the driving means be used as a fixed member and the permanent magnets be used as a movable member. In order to use the flat coil and the permanent coils as the fixed member and the movable member, respectively, the flat coil is fixed to one side surface of a plate fixed to the main body, and the permanent magnets are fixed to opposite inner surfaces of a channel- shaped yoke fixed to the display unit. The plate fixed to the main body is in the form of a rectangle with a predetermined width and length, and is fixed to the main body such that a longitudinal direction thereof is coincident with the sliding direction of the display unit. Further, the yoke is in the form of a channel with both open longitudinal sides, and is fixed to the display unit such that a longitudinal direction thereof is coincident with the sliding direction of the display unit. Moreover, the flat coil is fixed to one side surface of the plate and the permanent magnets are fixed in a pair to opposite inner surfaces of the yoke. The length of the yoke is smaller than the length of a section of the plate with the larger spacing of the windings in a portion of the plate where the flat coil is fixed, and the portion of the plate where the flat coil is fixed is placed in a space between the permanent magnets.

[12] In the driving means of the electronic device according to the present invention, the plate with the flat coil as the fixed member fixed thereto is disposed parallel with or perpendicularly to the upper surface of the main body, and the yoke with the permanent magnets as the movable member fixed thereto is fixed to the display unit, so that the display unit can be slide with respect to the main body. If the plate with the flat coil fixed thereto is disposed parallel with the upper surface of the main body, the driving means can be slimmed and the flat coil can be enlarged to obtain a large thrust. If the flat coil is disposed perpendicularly to the upper surface of the main body, the driving means can be installed at a side of the main body, resulting in a more slimmed and miniaturized electronic device.

[13] If the plate of the driving means is disposed parallel with the upper surface of the main body, one side of the plate is bent toward and fixed to the main body, and the yoke having an open lateral side is used, so that the portion of the plate where the flat coil is fixed can be received through the open lateral side and disposed between the pair of permanent magnets.

[14] Furthermore, the plate may be formed with a central portion protruding in the longitudinal direction thereof and fixed to the upper surface of the main body, both sides of the plate with respect to the central portion may be disposed to be spaced apart by a predetermined distance from and parallel with the upper surface of the main body, and the flat coil may be fixed to each of the both sides of the plate with respect to the central portion. In this case, the yoke to be fixed to the display unit has a lower surface that has an opening while facing the main body, and the permanent magnets are fixed in a pair to the opposite inner surfaces of the yoke, so that the both sides of the plate with respect to the central portion are disposed to be slidable in spaces between the pairs of opposite permanent magnets. The central portion of the plate is exposed through the opening of the yoke and then fixed to the main body. Since the flat coil is fixed to each of the both sides of the plate with respect to the central portion, si- multaneous flows of currents through the flat coils result in a greater thrust. Further, if the flat coils on the both sides of the plate with respect to the central portion are arranged such that the dense portions where the spacing of the windings is smaller and the sparse portions where the spacing of the windings is larger are located in reverse parallel, the flat coil at one side can be used for a forward movement of the movable member and the flat coil at the other side can be used for a reverse movement of the movable member.

[15] If the plate of the driving means is disposed perpendicularly to the upper surface of the main body, the portion of the plate where the flat coil is fixed is installed to be perpendicular to the upper surface of the main body, and the yoke having an open lower face facing the main body is used. The permanent magnets are fixed in a pair to the opposite inner surfaces of the yoke, and the portion of the plate where the flat coil is fixed is received through the open lower face and then disposed between the permanent magnets. In order to guide the sliding movement of the display unit and prevent the display unit from being separated from the main body, an end of the plate to be fixed to the main body is formed with a guide groove in the longitudinal direction, and the open lower face of the yoke has an end formed with a guide to be inserted into the guide groove.

[16] In the driving means of the portable electronic device according to the present invention, it is desirable in view of manufacture to use a printed circuit board with the flat coil printed on the plate without fixing the flat coil to the plate. In case of the use of the printed circuit board, it is possible to form a flat coil on a substrate accurately by printing, thereby making the size of the driving means very small. Moreover, in order to reinforce a magnetic flux generated in the flat coil, it is preferred that grooves be formed using a press in the printed circuit board between windings of the flat coil and silicon steel plates be then fixedly inserted into the grooves.

[17] The portable electronic device of the present invention preferably further comprises a holder means for maintaining the display unit at a stop position (at an opened or closed position) if an external force not greater than a predetermined value is applied to the display unit in the sliding direction at the opened or closed position where the display unit has been slid to open or close the main body. Although the holder means may be installed at the main body and the display unit, it is preferred that a resilient protrusion be installed on the plate and the yoke be formed with a recess in which the resilient protrusion is to be received.

[18] Furthermore, disengagement prevention protrusions are preferably installed at both longitudinal ends of the plate so as to limit a stroke of the display unit sliding with respect to the main body and to prevent the yoke from coming off from the plate.

[19] In the portable electronic device of the present invention, a switch is preferably installed in the main body so as to input a signal that enables supply of a current to the flat coil in order to slide the display unit. In order to prevent the display unit from being slid due to accidental pressing of the switch by other objects when the portable electronic device is stored in a bag or pocket, two switches are preferably installed at both sides of the main body.

[20] A sliding driving device according to another aspect of the present invention comprises a plate in the form of a rectangle with a predetermined width and length; a flat coil wound in a rectangular shape such that spacing of windings is smaller at one side and spacing of windings is larger at the other side along a sliding direction on a side surface of the plate; a yoke in the form of a channel with both open longitudinal sides; and a pair of permanent magnets fixed to opposite inner surfaces of the yoke such that different polarities of the permanent magnets face each other, wherein the length of the yoke is smaller than the length of a section of the plate with the larger spacing of the windings in a portion of the plate where the flat coil is fixed, and the portion of the plate where the flat coil is fixed is placed in a space between the permanent magnets.

[21] In addition, in view of mass productivity, the plate and the flat coil fixed to the plate are preferably formed of a printed circuit board. Furthermore, in case of the use of the printed circuit board, in order to reinforce a magnetic flux generated in the flat coil, it is more preferred that grooves be formed using a press in the printed circuit board between windings of the flat coil and silicon steel plates be then fixedly inserted into the grooves. Moreover, the driving means may further comprise a holder means for maintaining the display unit at a stop position if an external force not greater than a predetermined value is applied to the yoke in the sliding direction with respect to the plate, and disengagement prevention protrusions installed at both longitudinal ends of the plate so that the yoke is prevented from coming off from the plate. Brief Description of the Drawings

[22] Fig. 1 is an exploded perspective view of a portable electronic device having a sliding driving means using an electromagnetic force according to the present invention.

[23] Fig. 2 is a plan view showing a state where the driving means shown in Fig. 1 is installed.

[24] Fig. 3 is a sectional view of the driving means taken along line A-A in Fig. 2.

[25] Fig. 4 is a sectional view of the driving means taken along line B-B in Fig. 2.

[26] Fig. 5 (a) is an exploded perspective view of another embodiment of the driving means for use in a portable electronic device according to the present invention.

[27] Fig. 5 (b) is a sectional view taken along line C-C when the driving means shown in Fig. 5 (a) is assembled. [28] Fig. 6 is an exploded perspective view of a further embodiment of the driving means for use in a portable electronic device according to the present invention. [29] Fig. 7 (a) is an exploded perspective view of a still further embodiment of the driving means for use in a portable electronic device according to the present invention. [30] Fig. 7 (b) is a sectional view taken along line C-C when the driving means shown in

Fig. 7 (a) is assembled. [31] Fig. 8 is an exploded perspective view of a still further embodiment of the driving means for use in a portable electronic device according to the present invention. [32] Fig. 9 is a view illustrating a holder means used in the driving means of the present invention. [33] Fig. 10 is a view illustrating insertion of a silicon steel plate into a printed circuit board. [34] Fig. 11 is a view illustrating a portable electronic device employing a conventional driving means.

[35] <Explanation of Reference Numerals for Major Portions in Drawings>

[36] 10: Main body 20: Display unit

[37] 31: Yoke 32: Bearing

[38] 33, 34: Permanent magnet 41 : Plate

[39] 42: Flat coil 42a, 42b: Coil connection terminal

[40] 43, 46: Disengagement prevention protrusion 44, 45: Holder means

Best Mode for Carrying Out the Invention [41] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to accompanying drawings. [42] Fig. 1 is an exploded perspective view of a portable electronic device having a sliding driving means using an electromagnetic force according to the present invention, Fig. 2 is a plan view showing a state where the driving means shown in Fig.

1 is installed, Fig. 3 is a sectional view of the driving means taken along line A-A in

Fig. 2, and Fig. 4 is a sectional view of the driving means taken along line B-B in Fig.

2. [43] The portable electronic device of the present embodiment comprises a main body

10 with input buttons 13 installed on an upper surface thereof, a display unit 20 constructed to be slid with respect to the main body 10 and provided with a display means 21 such as an LCD, and a driving means 30 and 40. The input buttons 13 installed on the upper surface 15 of the main body 10 are exposed to the outside to input information when the display unit 20 is slid forward, and are concealed below the display unit 20 when the display unit 20 is slid backward. In such a sliding type mobile phone, the input buttons 13 are placed on the upper surface of the main body as described above, and thus, only a few input buttons 22 are provided on the display unit 20. Accordingly, there is an advantage in that the size of the display 21 can be increased. Although not illustrated in this embodiment, sliding guide means are provided on the upper surface 15 of the main body 10 and a lower surface of the display unit 20, respectively.

[44] In this embodiment, the driving means 30 and 40 allows the display unit 20 to be automatically slid using an electromagnetic force generated when a current flows through a wire placed within a magnetic field. The driving means 30 and 40 includes a yoke assembly 30 fixed to the lower surface of the display unit 20 and a plate assembly 40 fixed to the upper surface of the main body 10.

[45] The plate assembly 40 includes a plate 41 and a flat coil 42 fixed to an upper surface of the plate. The plate 41 is in the form of a rectangle and is arranged such that a longitudinal direction thereof is coincident with a sliding direction of the display unit 20. Referring to Fig. 3, one lateral side of the plate 41 is formed with a bent portion 41b bent toward the main body 10 and a fixed portion 41c to be fixed to the upper surface 15 of the main body 10, while the other lateral side of the plate 41 is formed with a portion 41a arranged parallel with the upper surface 15 of the main body 10. The conductive flat coil 42 is fixed to the parallel portion 41a of the plate 41. The flat coil 42 is wound in the form of a rectangle such that spacing of windings is smaller at one side and spacing of windings is larger at the other side along the sliding direction of the display unit 20 on an identical plane. In this embodiment, the plate 41 and the flat coil 42 have been implemented using a printed circuit board. In a case where a printed circuit board is employed, the number and spacing of windings can be conveniently determined. Although not shown, a coating for the protection and insulation of the flat coil 42 may be provided on an upper surface of the flat coil 42 fixed to the plate 41.

[46] Further, disengagement prevention protrusions 43 and 46 are provided on both longitudinal ends of the plate 41, respectively, to limit a sliding stroke of the yoke assembly 30 and to prevent the yoke assembly 30 from being disengaged from the plate 41. Reference numerals 42a and 42b designate starting and ending terminals of the flat coil 42, respectively, and terminals 14a and 14b for supplying the flat coil 42 with electric power are provided on the upper surface of the main body 10 fixed to the plate 41. Although not shown, the terminals 42a and 42b on the plate are electrically connected to the terminals 14a and 14b on the main body when the main body and the plate are assembled into the portable electronic device. Reference numeral 47 designates a through-hole through which a screw passes in order to fix the plate 41 to the main body 10.

[47] Although not shown, a control means is provided in the main body 10 to supply the flat coil 42 with a current when a switch 11 installed on a lateral side of the main body 10 is turned on. Further, reference numerals 12a and 12b designate sensors for detecting magnets 33 of the yoke assembly 30 which moved in a forward and backward direction. In this embodiment, magnet detection sensors 12a and 12b are used to detect the position of the yoke assembly 30 but other kinds of sensors or switches may be used.

[48] The yoke assembly 30 includes a yoke 31 made of magnetic metal and a pair of permanent magnets 33 and 34 fixed to the yoke 31. The yoke 31 fixes the pair of permanent magnets 33 and 34 and provides a magnetic flux passage to facilitate formation of a magnetic circuit. The yoke 31 is in the form of a channel with both open longitudinal sides, is fixed to the lower surface of the display unit 20 and is arranged such that a longitudinal direction thereof is coincident with the sliding direction of the display unit 20. Further, the yoke 31 has an open lateral side, and the permanent magnets 33 and 34 are fixed in a pair to opposite inner surfaces of the yoke 31. The parallel portion 41a of the plate 41 to which the flat coil 42 is fixed is inserted into the open lateral side of the yoke 3 land then placed in a space between the permanent magnets 33 and 34. Referring to Fig. 2, it is preferred that the width a of the permanent magnet be smaller than the minimum width c of the flat coil 42. This is to prevent a lateral force exerted on a longitudinal wire of the flat coil 42 from being generated when the wire is placed within a magnetic field. Further, a bearing 32 for supporting the plate 41 and guiding the sliding motion thereof is provided on an inner surface at a lateral side of the yoke 31 which is not open to the outside. Reference numeral 35 designates a through-hole through which a screw passes to fix the yoke 31 to the display unit 20.

[49] Referring again to Figs. 2 to 4, the operation of the driving means for use in the portable electronic device according to this embodiment will be explained. As shown in Fig. 2, the length b of the yoke assembly 30 is smaller than the length Ll of a section of the plate with the larger spacing of the windings in the portion 41a of the plate 41 where the flat coil 42 is fixed. Further, the disengagement prevention protrusions 43 and 46 are provided on both ends of the section with the larger spacing of the windings. Thus, the yoke assembly 30 can be slid forward or backward in a range between the disengagement prevention protrusions 43 and 46 in accordance with the direction of a current flowing along the flat coil 42 fixed to the plate 41. In a case where a current flows along the wire in a direction designated by an arrow ΓJ as shown in Fig. 2 and magnetic polarities of the magnets 33 and 34 are arranged as shown in Fig. 3 to create a magnetic field in a direction from the upper magnet 34 to the lower magnet 33, a force in a direction opposite to a direction designated by an arrow k shown in Fig. 2 is exerted on some of wires arranged perpendicularly to the direction of the magnetic field among the rectangular wires of the flat coil 42, pursuant to the Fleming's left-hand rule. Since the plate 41 with the flat coil 42 fixed thereto is fixed to the main body 10 and the display unit 20 with the yoke assembly fixed thereto is also provided to be slid with respect to the main body 10, the yoke assembly 30 with the permanent magnets 33 and 34 serving as a movable member fixed thereto is subjected to a force in an arrow direction according to the law of action and reaction and is then slid upwardly when viewed in Fig. 2. The yoke assembly 30 is slid downwardly when a current flows along the flat coil 42 in an opposite direction. The driving means of this embodiment thus configured can control the amount of the current supplied to the flat coil 42 to easily control the sliding speed. In other words, the driving means of this embodiment is convenient in that it is easily control the sliding speed by increasing the amount of current to speed up the yoke assembly when starting from a stopped state and alternatively decreasing the amount of current to speed down the yoke assembly when stopping the sliding motion.

[50] The operation of the portable electronic device according to this embodiment will be discussed. When a sliding command is inputted to the switch 11 provided on the lateral side of the main body, the control means (not shown) provided in the main body allows a current to be supplied to the flat coil 42. If the flat coil 42 is supplied with the current, the display unit 20 with the yoke assembly 30 fixed thereto is slid in a direction (a direction determined by a current direction and a stopped position) by means of the driving means 30 and 40. The magnet detection sensors 12a and 12b provided on the main body 10 detect whether the display unit 20 has been slid to a predetermined position, and the control means provided within the main body cuts off the current supplied to the flat coil 42.

[51] Referring to Figs. 3 and 4, a holder means 44 is provided in the driving means of this embodiment such that the display unit 20 can be maintained at a certain position when an external force of which the amplitude is smaller than a predetermined value is exerted thereto. The holder means 44 of this embodiment includes a ball 44a provided in a through-hole 44c formed through the plate 41, a spring 44b for supporting the ball 44a, and a cap 44d fitted into the through-hole 44c for supporting the spring 44b. As shown in Fig. 3, the through-hole 44c is composed of a small diameter portion and a large diameter portion. In such a case, the diameter of the large diameter portion is greater than that of the ball 44a and the diameter of the small diameter portion is smaller than that of the ball 44a, so that a portion of the ball 44a is exposed through the small diameter portion of the through-hole. A groove 32b for accommodating the exposed portion of the ball 44a is formed at a predetermined position in the bearing 32 provided in the yoke 31. The exposed portion of the ball 44a is inserted in the groove 32b to resiliency support the display unit 20 such that the display unit cannot be slid when the external force of which the amplitude is smaller than a predetermined value is exerted on the display unit. Fig. 9 shows another embodiment of the holder means. In the embodiment shown in Fig. 9 where the holder means 44 are formed integrally with the disengagement prevention protrusion 43, a resilient spring in the form of a bent strip is used in such a manner that one end thereof serves as the disengagement prevention protrusion 43 and the other end thereof serves as the holder means 44.

[52] Regardless of the use of the holder means, the portable electronic device of the present invention can be configured such that the control means supplies the flat coil with the current to return the display unit 20 to the predetermined position if the detection sensors 12a and 12b detect that the display unit 20 has been slid out of the predetermined position without operating the switch 11.

[53] Fig. 5 (a) is an exploded perspective view of another embodiment of the driving means for use in a portable electronic device according to the present invention, and Fig. 5 (b) is a sectional view taken along line C-C when the driving means shown in Fig. 5 (a) is assembled.

[54] The driving means of the embodiment shown in Fig. 5 is different from that of the embodiment shown in Figs. 1 to 4, in that a protruding central portion 48 is formed along a longitudinal direction of the plate 41 and then fixed to the upper surface 15 of the main body and that a pair of flat coils 42 and 52 are fixed to both sides 41a and 4 Id of the plate with respect to the central portion 48, respectively. Further, the yoke 31 is constructed to have a lower surface that has an opening while facing the main body and closed lateral sides 31b and 3 Id, so that the both sides 41a and 42d of the plate with the pair of flat coils 42 and 52 fixed thereto can be fitted in the yoke 20. Further, permanent magnets 33, 34, 37 and 38 are fixed in pairs at positions on the inner surfaces of the yoke 31 corresponding respectively to the flat coils 42 and 52. That is, two driving means such as that shown in Fig. 1 are connected to each other such that they can be positioned to be symmetric with respect to each other. The plate assembly 40 is fixed to the main body by tightening screws into through-holes 47 formed through the central portion 48, and the yoke assembly 30 is fixed to the display unit 20 by tightening screws into through-holes 35 formed in a central portion thereof. If the driving means of this embodiment is employed in the portable electronic device, it is not necessary to provide an additional sliding guide means on the main body 10 or the display unit 20. The reason is that a pair of bearings 32 and 36 are provided in the closed lateral sides 31b and 3 Id of the yoke 31 and the lateral sides of the plate 41 are fitted into the grooves formed in the bearings 32 and 36 such that the main body and the display unit can be guided with respect to each other. A greater thrust can be obtained from the driving means of this embodiment by causing currents to flow along the flat coils at the same time, because the flat coils 42 and 52 are fixed to the both sides of the plate 41 with respect to the central portion 48.

[55] Fig. 6 is an exploded perspective view of a further embodiment of the driving means for use in the portable electronic device according to the present invention. The driving means of the embodiment shown in Fig. 6 is different from that of the embodiment shown in Fig. 5, in that a pair of flat coils 42 and 62 fixed respectively to the both sides of the plate 41 with respect to the central portion 48 are arranged such that sparse portions (portions with smaller spacing of windings) of the flat coils 42 and 62 face dense portions (portions with larger spacing of windings) of the flat coils 62 and 42, respectively. The permanent magnets 33, 34, 37 and 38 are arranged with the same polarities as shown in Fig. 5. Accordingly, the display unit 20 with the yoke assembly 30 fixed thereto may be moved either forward by causing a current to flow along one flat coil 42 or backward by causing a current to flow along the other flat coil 62.

[56] Fig. 7 (a) is an exploded perspective view of a still further embodiment of the driving means for use in the portable electronic device according to the present invention, and Fig. 7 (b) is a sectional view taken along line C-C when the driving means shown in Fig. 7 (a) is assembled. The driving means of the embodiment shown in Fig. 7 is different from that of the embodiment shown in Fig. 5 or 6, in that a pair of flat coils 72 and 82 are further fixed to the lower surface of the plate. Accordingly, a greater thrust can be obtained from the embodiment shown in Fig. 7 as compared with the embodiment shown in Fig. 5 or 6, if the driving means with the same size is employed.

[57] Fig. 8 is an exploded perspective view of a still further embodiment of the driving means for use in the portable electronic device according to the present invention. The driving means of this embodiment is different from those of the embodiments shown in Figs. 1 to 6, in that the portion of the plate 41 of the plate assembly 40 where the flat coil 42 is fixed is arranged perpendicularly to the upper surface 15 of the main body 10. Further, the yoke 31 of the yoke assembly 30 is configured to have an open lower face facing the upper surface 15 of the main body. The permanent magnets 33 and 34 are fixed in a pair to the opposite inner surfaces of the yoke 31. The plate assembly 40 is fixedly inserted into a groove 16 formed in the upper surface 15 of the main body 10. The yoke assembly 30 is fixedly inserted into a fixing groove 24 formed in the lower surface of the display unit 20, and slots 25 through which the plate 41 passes when the display unit 20 is slid are formed to extend from both longitudinal ends of the fixing groove 24. The portion of the plate 41 where the flat coil 42 is fixed is received through the open lower face of the yoke 31 and is placed between the pair of permanent magnets 33 and 34. Further, guide grooves 49 are formed at both sides of an end of the plate 41 to be fixed to the upper surface 15 of the main body 10 in a sliding direction of the display unit 20 in order to guide the sliding motion of the display unit 20 and to prevent the display unit 20 and the main body 10 from being disengaged from each other. Furthermore, guides 38 are formed at both sides of the open lower face of the yoke 31 in a longitudinal direction of the yoke 31 such that they can be inserted into the guide grooves 49. Accordingly, if the driving means of this embodiment is employed in the portable electronic device, it is not necessary to provide an additional sliding guide means on the main body 10 or the display unit 20.

[58] Since the operational principle of the driving means shown in Figs. 5 to 8 is identical with that of the driving means shown in Fig. 1, a description of the operation thereof will be omitted.

[59] Referring to Fig. 10, if the plate 41 and the flat coil 42 are formed of a printed circuit board, grooves may be formed using a press in the plate 41 between windings and silicon steel plates 48 may be then inserted into the grooves in order to reinforce a magnetic force. Industrial Applicability

[60] The present invention provides a slim type portable electronic device in which a display unit can be automatically slid with respect to a main body by means of an electromagnetic force. Particularly, a flat coil wound such that the directions of currents flowing though windings of the coil are identical to one another is used between a pair of permanent magnets, so that it is possible to manufacture a slim type portable electronic device.

[61] Further, since a portable electronic device according to the present invention can generate a thrust by merely causing a current to flow through a flat coil of a driving means, the driving means can be easily controlled and the portable electronic device can be manufactured at low costs.

[62] The embodiments of the present invention described above and illustrated in the drawings should not be construed as limiting the technical spirit of the present invention. The scope of the present invention is limited only by the appended claims. Those skilled in the art can modify and change the technical spirit of the present invention in different forms. Therefore, such modifications and changes will fall within the scope of the present invention so far as they are apparent to those skilled in the art.

Claims

[1] A portable electronic device, comprising: a main body having an upper surface provided with an input means for use in inputting information; a display unit installed to be slidable in a direction over the upper surface of the main body and provided with a display means for displaying information provided by the main body; and a driving means having a flat coil wound in a rectangular shape such that spacing of windings is smaller at one side and spacing of windings is larger at the other side along the sliding direction of the display unit on an identical plane, and a pair of permanent magnets spaced apart by a predetermined distance from each other such that different polarities thereof face each other in a state where the plane on which the flat coil is wound is interposed between the permanent magnets, wherein the flat coil and the permanent magnets are installed between the main body and the display unit such that the display unit can be slid with respect to the main body by means of an electromagnetic force generated when a current flows through the flat coil.

[2] The portable electronic device according to Claim 1, wherein the driving means comprises: a plate in the form of a rectangle with a predetermined width and length, the plate being fixed to the main body such that a longitudinal direction thereof is coincident with the sliding direction of the display unit; and a yoke in the form of a channel with both open longitudinal sides, the yoke being fixed to the display unit such that a longitudinal direction thereof is coincident with the sliding direction of the display unit, wherein the flat coil is fixed to one side surface of the plate and the permanent magnets are fixed in a pair to opposite inner surfaces of the yoke, and the length of the yoke is smaller than the length of a section of the plate with the larger spacing of the windings in a portion of the plate where the flat coil is fixed, and the portion of the plate where the flat coil is fixed is placed in a space between the permanent magnets.

[3] The portable electronic device according to Claim 2, wherein one side of the plate is bent toward and fixed to the main body, and the portion of the plate where the flat coil is fixed is disposed to be spaced apart by a predetermined distance from and parallel with the upper surface of the main body; and the yoke has an open lateral side, and the portion of the plate where the flat coil is fixed is received through the open lateral side and disposed between the pair of permanent magnets.

[4] The portable electronic device according to Claim 2, wherein the plate has a central portion protruding in the longitudinal direction and fixed to the upper surface of the main body, both sides of the plate with respect to the central portion are disposed to be spaced apart by a predetermined distance from and parallel with the upper surface of the main body, and the flat coil is fixed to each of the both sides of the plate with respect to the central portion; the yoke has a lower surface that has an opening while facing the main body, and the permanent magnets are fixed in a pair to the opposite inner surfaces of the yoke; and the central portion of the plate is exposed through the opening of the yoke and then fixed to the main body, and the both sides of the plate with respect to the central portion are disposed to be slidable in spaces between the pairs of opposite permanent magnets.

[5] The portable electronic device according to any one of Claims 2 to 4, wherein the plate and the flat coil fixed to the plate are formed of a printed circuit board.

[6] The portable electronic device according to Claim 5, wherein the driving means further comprises a holder means for maintaining the display unit at a stop position if an external force not greater than a predetermined value is applied to the display unit in the sliding direction.

[7] The portable electronic device according to Claim 6, wherein the driving means further comprises disengagement prevention protrusions installed at both longitudinal ends of the plate so that the yoke is prevented from coming off from the plate when the display unit is slid.

[8] The portable electronic device according to Claim 7, further comprising a switch installed in the main body so as to input a signal for enabling supply of a current to the flat coil.

[9] The portable electronic device according to Claim 2, wherein the portion of the plate where the flat coil is fixed is installed to be perpendicular to the upper surface of the main body, and the yoke has an open lower face facing the main body, the permanent magnets are fixed in a pair to the opposite inner surfaces of the yoke, and the portion of the plate where the flat coil is fixed is received through the open lower face and then disposed between the permanent magnets.

[10] The portable electronic device according to Claim 9, wherein an end of the plate to be fixed to the main body is formed with a guide groove in the longitudinal direction, and the open lower face of the yoke has an end formed with a guide to be inserted into the guide groove, thereby guiding the sliding movement of the display unit and preventing the display unit from being disengaged from the main body.

[11] The portable electronic device according to Claim 9 or 10, wherein the plate and the flat coil fixed to the plate are formed of a printed circuit board.

[12] The portable electronic device according to Claim 11, wherein the driving means further comprises a holder means for maintaining the display unit at a stop position if an external force not greater than a predetermined value is applied to the display unit in the sliding direction.

[13] The portable electronic device according to Claim 12, wherein the driving means further comprises disengagement prevention protrusions installed at both longitudinal ends of the plate so that the yoke is prevented from coming off from the plate when the display unit is slid.

[14] The portable electronic device according to Claim 5, wherein the driving means further comprises silicon steel plates fixedly inserted between the windings of the flat coil.

[15] A sliding driving device, comprising: a plate in the form of a rectangle with a predetermined width and length; a flat coil wound in a rectangular shape such that spacing of windings is smaller at one side and spacing of windings is larger at the other side along a sliding direction on a side surface of the plate; a yoke in the form of a channel with both open longitudinal sides; and a pair of permanent magnets fixed to opposite inner surfaces of the yoke such that different polarities of the permanent magnets face each other, wherein the length of the yoke is smaller than the length of a section of the plate with the larger spacing of the windings in a portion of the plate where the flat coil is fixed, and the portion of the plate where the flat coil is fixed is placed in a space between the permanent magnets.

[16] The sliding driving device according to Claim 15, wherein the plate and the flat coil fixed to the plate are formed of a printed circuit board.

[17] The sliding driving device according to Claim 16, further comprising a holder means for maintaining the display unit at a stop position if an external force not greater than a predetermined value is applied to the yoke in the sliding direction.

[18] The sliding driving device according to Claim 17, further comprising disengagement prevention protrusions installed at both longitudinal ends of the plate so that the yoke is prevented from coming off from the plate.