Lens driving device, camera device, and electronic equipment

Abstract

The present invention provides a lens driving device, a camera device, and an electronic device, wherein a movable body can move smoothly. The lens driving device (5) comprises: a fixed body including a housing (10), a magnetic plate (20), and a base (50); a movable body including a spring component (30), a magnet (39), and a lens holding portion (40); a driving shaft (82); and a guide shaft (81). The driving shaft (82) is freely mounted on the fixed body with a back-and-forth asymmetric micro-vibration, and the guide shaft (81) is separated from the driving shaft (82) and fixed to the fixed body. The movable body sandwiches and holds the driving shaft (82) with the spring component (30) and is engaged with the guide shaft (81). Between the driving shaft (82) and the guide shaft (81), the magnet (39) mounted on the lens holding portion (40) is attracted to the magnetic plate (20) mounted on the base (50).

Description

Technical Field

[0001] The present invention relates to a lens driving device, a camera device, and an electronic device used in electronic devices such as smartphones. Background Art

[0002] Some camera devices with AF (Auto Focus) functions use piezoelectric elements as a driving source for a movable body that holds a lens. Patent Document 1 is a document that discloses technology related to such a camera device. The focus adjustment module of the lens described in Patent Document 1 houses a movable body that holds a lens on a base, and holds the movable body by a drive shaft and a guide shaft that rise from two corners of the base. The movable body is moved along the optical axis by the forward and backward movement of the drive shaft. In addition, in the focus adjustment module, magnets and magnetic bodies are arranged on the inner wall of the base and the outer wall of the movable body. The magnetic attraction between the magnets and the magnetic body is used to push the movable body against the drive shaft and the guide shaft in a non-tilted manner.

[0003]

Prior art literature

[0004] [Patent Literature]

[0005] [Patent Document 1] Korean Registered Patent No. 1483782B Summary of the Invention

[0006] [Problems to be solved by the invention]

[0007] However, in recent years, the stroke of the movable body and the weight of the lens in lens drive devices have increased. With this increase in the movable body's stroke or lens weight, the technique of Patent Document 1 requires increasing the attractive force between the magnet and the magnetic body to maintain the movable body's posture. Consequently, the force pressing the movable body against the drive shaft and guide shaft also increases, making it difficult for the movable body to move smoothly.

[0008] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a lens driving device in which a movable body moves smoothly.

[0009]

Methods for solving the problem

[0010] In order to solve the above-mentioned problems, a lens driving device as a preferred embodiment of the present invention is characterized in that it includes a fixed body, a movable body, a driving shaft and a guide shaft, the driving shaft is freely mounted on the fixed body by asymmetric micro-vibration, the guide shaft is separated from the driving shaft and fixed to the fixed body, the movable body clamps and holds the driving shaft with a spring component, and is engaged with the guide shaft, between the driving shaft and the guide shaft, one of the fixed body and the movable body has a magnet, and the other has a second magnet or a soft magnetic component that is attracted to the magnet.

[0011] In this aspect, the spring member may include a second soft magnetic member and be arranged between the magnet and the second magnet or the soft magnetic member.

[0012] Furthermore, the saturation magnetic flux density of the second soft magnetic member may be smaller than the saturation magnetic flux density of the soft magnetic member.

[0013] Alternatively, the fixed body may have a base plate, two columns extending from the corners of the base plate, and a support plate extending from the base plate between the two columns, and the soft magnetic component may be a plate body, with the left and right ends of one plate surface being fixed to the columns, and the rear end of the other plate surface being fixed to the support plate.

[0014] Furthermore, the soft magnetic member has a structure for fixing the drive shaft and the guide shaft.

[0015] A camera device according to another preferred embodiment of the present invention is characterized by including the above-mentioned lens driving device.

[0016] Another preferred embodiment of the present invention provides an electronic device including the camera device described above.

[0017] Effects of the Invention

[0018] The lens drive device of the present invention comprises a fixed body, a movable body, a drive shaft, and a guide shaft. The drive shaft is mounted on the fixed body so as to be freely movable in a reciprocating asymmetric microvibration. The guide shaft is separated from the drive shaft and fixed to the fixed body. The movable body sandwiches and holds the drive shaft with a spring component and is engaged with the guide shaft. Between the drive shaft and the guide shaft, one of the fixed body and the movable body has a magnet, and the other has a second magnet or a soft magnetic component that attracts the magnet. Thus, the movable body is supported by the drive shaft and the guide shaft in addition to the attraction between the magnet and the magnetic body, thereby providing a lens drive device that is easy to maintain and allows the movable body to move smoothly. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a front view of a smartphone 9 equipped with a camera device 8 including a lens driving device 5 as one embodiment of the present invention.

[0020] Figure 2 yes Figure 1 A three-dimensional diagram of the lens driving device 5.

[0021] Figure 3 It is decomposed Figure 2 A three-dimensional diagram of the lens driving device 5.

[0022] Figure 4 It is from Figure 2 The perspective view shows the housing 10 removed.

[0023] Figure 5 It is from Figure 4 A perspective view with the magnetic plate 20 removed.

[0024]

Explanation of symbols

[0025] 5 Lens drive device; 6 Lens body; 7 Image sensor; 8 Camera device; 9 Smartphone; 10 Housing; 11 Through-hole; 12 Front plate; 20 Magnetic plate; 21 Rectangular portion; 22 End plate portion; 30 Spring component; 31 Receiving plate; 32 Pressing plate; 33 Flat plate portion; 34 Groove portion; 35 Pressing portion; 39 Magnet; 40 Lens holding portion; 41 Through-hole; 42 Magnet storage portion; 43 Second carrier portion; 50 Base; 51 Bottom plate; 52 Through-hole; 54 Column portion; 55 Lens drive device; 80 Rubber bushing; 81 Guide shaft; 82 Drive shaft; 83 Vibrating component; 84 Adhesive; 280 Circular hole; 335 Positioning hole; 380 Gap; 434 Protrusion; 435 Positioning protrusion; 480 Groove; 481 Hook portion; 530 Support plate; 540 First carrier portion; 580 Circular hole DETAILED DESCRIPTION

[0026] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 As shown, a camera device 8 including a lens driving device 5 according to one embodiment of the present invention is housed in a smartphone 9 .

[0027] The camera device 8 includes a lens 6 , an image sensor 7 that converts light incident through the lens 6 into an image signal, and a lens driving device 5 that holds the lens 6 and the image sensor 7 and drives the lens 6 with respect to the image sensor 7 .

[0028] Hereinafter, the direction in which light from the subject is incident will be referred to as the Z direction, the direction perpendicular to the Z direction will be referred to as the X direction, and the direction perpendicular to both the Z and X directions will be referred to as the Y direction. Furthermore, the +Z side of the lens 6, which is the subject side of the optical axis, will sometimes be referred to as the front side, and the -Z side, which is the side opposite to the subject and on which the image sensor 7 is provided, will sometimes be referred to as the rear side. Furthermore, the -Y side will sometimes be referred to as the left side, the +Y side as the right side, the -X side as the top side, and the +X side as the bottom side.

[0029] The lens driving device 5 includes a housing 10, a magnetic plate 20, a spring member 30, a magnet 39, a lens holder 40, a base 50, a rubber bushing 80, a guide shaft 81, a drive shaft 82, and a vibrating member 83. The housing 10, magnetic plate 20, and base 50 constitute a fixed body, while the spring member 30, magnet 39, and lens holder 40 constitute a movable body.

[0030] The housing 10 is in the shape of a box with one side open. A through hole 11 is provided at the center of a front plate 12 of the housing 10 .

[0031] The base 50 has a bottom plate 51 in the shape of a rectangular plate. A through hole 52 is provided in the center of the bottom plate 51. On the rear side of the base 50, the image sensor 7 is fixed with its light-receiving surface facing the through hole 52. In addition to the opening 59, side plates 53 are formed around the bottom plate 51 toward the rear. At the four corners of the front surface of the plate 51, four columns 54 extending toward the front are provided. The column 54 is bent in an L shape along the corner of the base 50 when viewed from the Z direction. The column 54 has a double structure, and the inner part is guided further forward than the outer part. The inner parts of the two columns 54 on the +X+Y side and the +XY side further extend toward the other side to form the first carrier parts 540 respectively. The two first carrier parts 540 are formed on the same plane.

[0032] The front surface of the bottom plate 51 between the two pillars 54, 54 is positioned slightly lower than the front surface of the bottom plate 51 surrounding the through-hole 52. A further lowered front surface is provided at the outermost edge of the bottom plate 51, including the outer sides of each pillar 54, where the rear surface of the housing 10 is placed and secured. Two circular holes 580 are provided on the inner sides of the two pillars 54 on the +X+Y and +XY sides of the base 50. A support plate 530 extends forward from the center of the lower edge of the front surface between the two pillars 54, 54, where the first receiving portion 540 is formed. When viewed from the Y direction, a gap corresponding to the thickness of the magnetic plate 20, described later, is provided between the first receiving portion 540 and the support plate 530.

[0033] The lens holding portion 40 is roughly rectangular. The lens holding portion 40 is provided with a through hole 41 for fixing the lens body 6. In the center of the lower surface of the lens holding portion 40, a magnet receiving portion 42 is recessed upward and fixes the magnet 39. On the left and right sides of the magnet receiving portion 42, a second carrier portion 43 is provided, and the magnet 39 received in the magnet receiving portion 42 is recessed more than the second carrier portion 43. The two second carrier portions 43 are formed on the same plane. At the front and rear ends of the second carrier portion 43 on the left side, a convex portion 434 is provided to protrude downward. On the second carrier portion 43 on the right side, two positioning protrusions 435 arranged in parallel front and back are provided to protrude downward.

[0034] A V-shaped recessed groove 480 extending forward and backward is provided on the left side of the left second loading portion 43. A U-shaped hook 481 extending forward and backward is provided on the right side of the right second loading portion 43.

[0035] The magnetic plate 20, a soft magnetic component, is made of a soft magnetic material such as iron with a high saturation magnetic flux density. It has a rectangular portion 21 and end plate portions 22 that are bent upward from the left and right edges of the front side of the rectangular portion 21. Round holes 280 are provided in the end plate portions 22. The rear portions of the left and right ends of the rectangular portion 21 are slightly narrower.

[0036] The magnetic plate 20 is placed and adhesively fixed on the first mounting portion 540 of the two pillars 54 on the +X+Y side and the +XY side, abutting the front surface between the two pillars 54. At this time, the lower surface of the magnetic plate 20 is approximately in contact with the upper surface of the support plate 530. Further fixing can also be performed at each abutting location.

[0037] The spring component 30 is formed by bonding two plates, a receiving plate 31 and a pressing plate 32. The receiving plate 31 has a flat plate portion 33 and a groove portion 34. The flat plate portion 33 has a positioning hole 335 corresponding to the positioning protrusion 435 and is placed on the two second receiving portions 43, 43. The groove portion 34 is formed in a V-shape so as to fit into the groove 480. The receiving plate 31 is then fixed to the second receiving portions 43, 43 and the groove 480. The pressing plate 32 is a flat plate, and when bonded to the receiving plate 31, the position corresponding to the groove portion 34 becomes the pressing portion 35. The positions of the spring component 30 corresponding to the protrusions 434, 434 are recessed in the forward or rearward direction, respectively. A triangular gap 380 is formed between the groove portion 34 and the pressing portion 35, and the drive shaft 82 described later is inserted so as to open the gap 380. That is, the lens holding portion 40 holds the driving shaft 82 by pushing the driving shaft 82 against the groove portion 34 with the pressing portion 35 so as to sandwich the driving shaft 82 .

[0038] At least the pressing plate 32 of the spring member 30 has elasticity. Furthermore, at least one of the receiving plate 31 or the pressing plate 32, serving as the second soft magnetic member, is made of a soft magnetic material having a saturation magnetic flux density lower than that of the material constituting the magnetic plate 20. A low saturation magnetic flux density of 1.5 T or less is particularly preferred, and examples of such a material include magnetic stainless steel.

[0039] The guide shaft 81 passes through the circular hole 580 on the +X+Y side of the base 50. The rear edge of the guide shaft 81 is fixed to the circular hole 580 on the +X+Y side. The front edge of the guide shaft 81 is fixed to the circular hole 280 on the right side of the magnetic plate 20. The lens holder 40 engages with the guide shaft 81 via the upper and lower inner surfaces of the hook portion 481.

[0040] A drive shaft 82 passes through a circular hole 580 on the +XY side of the base 50 via a rubber bushing 80. The rubber bushing 80 is annular, with the outer side fitting into the circular hole 580 and the inner side receiving the drive shaft 82. The rear end of the drive shaft 82 penetrates the rubber bushing 80 and is bonded to a vibrating member 83 via adhesive 84. The vibrating member 83 is formed by bonding a piezoelectric sheet and an elastic sheet. An electrical circuit (not shown) for the piezoelectric sheet is provided through the opening 59.

[0041] The front end of the drive shaft 82 is fixed to the circular hole 280 on the left side of the magnetic plate 20. The drive shaft 82 is held by the spring member 30 in the lens holder 40. The groove 34 and the inner surface of the pressing portion 35 of the spring member 30 are frictionally engaged with the drive shaft 82.

[0042] The magnet 39 and magnetic plate 20 provided in the lens holder 40 attract each other. Consequently, the lens holder 40 is pressed against the guide shaft 81 and the drive shaft 82, making it easier to maintain its position. Furthermore, a spring member 30 composed of a relatively weakly magnetic soft magnetic material is positioned between the magnet 39 and the magnetic plate 20. This reduces the magnetic attraction of the magnet 39 on the magnetic plate 20 by an appropriate amount, thereby significantly reducing the magnetic attraction relative to the driving force of the vibrating member 83 on the drive shaft 82, which will be described later.

[0043] When a predetermined pulse voltage is repeatedly applied to the piezoelectric thin plate of the vibrating component 83, the piezoelectric thin plate expands and contracts, causing the vibrating component 83 to deform slightly. This causes the drive shaft 82 to repeatedly perform minute reciprocating motions in the Z direction. For example, when the duty cycle of this pulse is changed from 50%, the drive shaft 82 moves at a low speed in the +Z direction and at a high speed in the -Z direction. This causes the lens holder 40 to repeatedly follow the drive shaft 82 when it moves in the +Z direction, and then remain in position when it moves in the -Z direction, intermittently moving in the +Z direction. When the duty cycle is changed from 50%, the opposite motion occurs.

[0044] The above are the details of this embodiment. The lens drive device 5 in this embodiment includes: a fixed body comprising a housing 10, a magnetic plate 20, and a base 50; a movable body comprising a spring member 30, a magnet 39, and a lens holder 40; a drive shaft 82, and a guide shaft 81. The drive shaft 82 is mounted on the fixed body so as to be free to reciprocate with asymmetric microvibration. The guide shaft 81 is separated from the drive shaft 82 and fixed to the fixed body. The movable body sandwiches and holds the drive shaft 82 with the spring member 30 and is engaged with the guide shaft 81. Between the drive shaft 82 and the guide shaft 81, the magnet 39 mounted on the lens holder 40 is attracted to the magnetic plate 20 mounted on the base 50. Thus, the movable body is supported by the drive shaft 82 and the guide shaft 81 in addition to the attractive force between the magnet 39 and the magnetic plate 20. This makes it easier to maintain its posture, thus providing a lens drive device 5 in which the movable body moves smoothly.

[0045] Furthermore, in the above embodiment, the magnet 39 may be provided on the fixed body, and a magnetic body may be provided on the movable body.

[0046] Alternatively, the magnetic plate 20 may be replaced with a second magnet attracted to the magnet 39. When a magnet is provided on the fixed body, a plate having the same shape as the magnetic plate 20 may be placed in its place to fix the drive shaft 82 and the guide shaft 81.

Claims

1. A lens driving device, characterized in that: have: fixed body; active body; drive shaft; and guide shaft; The drive shaft is mounted on the fixed body so as to be free to reciprocate with asymmetric micro-vibration. The guide shaft is fixed to the fixed body separately from the drive shaft. The movable body holds the driving shaft by a spring member and is engaged with the guide shaft. Between the drive shaft and the guide shaft, one of the fixed body and the movable body has a magnet, and the other has a second magnet or a soft magnetic member attracted to the magnet. The spring member includes a second soft magnetic member and is disposed between the magnet and the second magnet or the soft magnetic member.

2. The lens driving device according to claim 1, wherein: The saturation magnetic flux density of the second soft magnetic member is smaller than the saturation magnetic flux density of the soft magnetic member.

3. The lens driving device according to claim 1, wherein: The fixed body comprises a bottom plate, two pillars extending from corners of the bottom plate, and a support plate extending from the bottom plate between the two pillars. The soft magnetic component is a plate body, the left and right ends of one plate surface are fixed to the column portion, and the rear end of the other plate surface is fixed to the support plate.

4. The lens driving device according to claim 1 or 3, wherein: The soft magnetic member has a structure for fixing the drive shaft and the guide shaft.

5. A camera device, characterized in that: The lens driving device comprises the lens driving device according to any one of claims 1 to 4.

6. An electronic device, characterized in that: The device comprises the camera device according to claim 5 .

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