JP2005250086A - Lens driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens driving device exactly moving a lens supporting body stably by a desired amount in narrow space with simple structure, and suitably mounted in a compact camera. <P>SOLUTION: The lens driving device 1 has a 1st lens supporting body 12 made cylindrical, which is arranged movably between a 1st magnet 6 and a 2nd magnet 8 and holds a 1st annular coil 20 on its outer periphery, and a 2nd lens supporting body 14 made cylindrical, which is arranged movably between the 2nd magnet 8 and a 3rd magnet 10 and holds a 2nd annular coil 22 on its outer periphery. The 1st lens supporting body 12 is linearly moved by electromagnetic force induced by a current applied to the coil 20 and magnetic field formed by the magnets 6 and 8, and the 2nd lens supporting body 14 is linearly moved by electromagnetic force induced by a current applied to the coil 22 and magnetic field formed by the magnets 8 and 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a lens driving device for driving a zoom lens and an autofocus lens used in a portable small camera or the like built in a digital camera or a mobile phone, and in particular, moves the lens linearly by electromagnetic force. The present invention relates to a lens driving device that can be used.

  In general, a lens driving device that linearly drives a lens by an electromagnetic force induced by a current flowing through a coil and a magnetic field formed by a magnet is well known. For example, Patent Document 1 discloses a lens driving device for magnetically driving a zoom lens and an autofocus lens used in a video camera or the like.

Japanese Patent Laid-Open No. 2002-23037

  By the way, in a lens driving device used for a portable small camera such as a camera built in a cellular phone or the like, it is necessary to move the lens in a narrow space stably and accurately by a desired amount. There is, but it is difficult to realize this with a simple structure.

  The present invention has been made paying attention to the above-mentioned circumstances, and an object of the present invention is to a small camera that can move a lens support stably and accurately in a narrow space by a simple structure in a narrow space. It is providing the lens drive device suitable for mounting.

  The lens driving device according to claim 1 includes a cylindrical yoke, and three first annular rings that are coaxially accommodated in the yoke and are spaced apart from each other along the axial direction of the yoke. A cylindrical first lens support member that is movably disposed between the second and third magnets, and that holds an annular first coil on the outer periphery thereof; A cylindrical second lens support body, which is movably disposed between the second magnet and the third magnet and holds an annular second coil on the outer periphery thereof, and the first lens support body, The second lens support is moved linearly by the electromagnetic force induced by the current flowing through the coil and the magnetic field formed by the first magnet and the second magnet, and the second lens support is moved by the second magnet. And third magnet Characterized in that it is moved linearly by the electromagnetic force induced by the magnetic field formed.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, the three magnets are spaced apart in the axial direction at equal distances.

  The invention according to claim 3 is the invention according to claim 1 or 2, further comprising guide means for guiding the linear movement of the lens support.

  According to a fourth aspect of the present invention, in the invention of the third aspect, the guide means is provided in common to the two lens supports, and includes at least one shaft that passes through the lens supports in the axial direction. It is characterized by comprising.

  According to the lens driving device of the first aspect, two magnetic field spaces are formed in the cylindrical yoke adjacent to each other in the axial direction by the three annular magnets arranged coaxially. Two cylindrical lens supports are individually associated with each magnetic field space and individually moved. Therefore, linear movement of the pair of lenses can be realized with a very compact configuration. Also, the magnetic field space for moving each lens support is formed separately by dividing the inside of the yoke in the axial direction, so even if both lens supports are moved simultaneously, the repulsion of magnetic force, etc. The influence of the coil on the coil can be minimized. That is, for example, when two lens supports are moved simultaneously in a common magnetic field space, the movement of the two lens supports is hindered by the magnetic interaction between the coils. Such a problem can be minimized if the magnetic field space in which the magnetic field is moved is separately formed.

  Further, in the above configuration, since the pair of lens supports are arranged apart from each other along the optical axis direction, if the zoom lens and the focus lens are respectively supported on each lens support, the auto focus is achieved. A compact lens driving device having both a mechanism and a magnification changing function can be efficiently realized.

  Further, since the lens is linearly moved in the optical axis direction by the electromagnetic force generated by energizing the coil, the direction of the thrust and the direction of movement of the lens coincide with each other, so that the drive loss is extremely small. As a result, the moving speed of the lens can be increased and the responsiveness can be improved. In other words, since the drive loss is small and the response and mobility are excellent, the lens can be efficiently moved by a desired amount in the optical axis direction in a narrow space, which is suitable for mounting on a small camera.

  According to the lens driving device of the second aspect, the same effect as that of the invention of the first aspect can be obtained, and the three magnets are spaced apart from each other in the axial direction at an equal distance. Attenuation of electromagnetic force accompanying the movement of the support can be minimized. That is, when the two lens supports are moved in one magnetic field space formed by the first magnet and the third magnet without disposing the second magnet between the first magnet and the third magnet. As the distance from the magnet increases, the electromagnetic force acting on the lens support decreases, making it difficult to perform accurate movement control, but it is equal between the first magnet and the third magnet. When the second magnet is arranged at a distance (in the center between the first magnet and the third magnet), attenuation of electromagnetic force accompanying movement of the lens support can be minimized, and accurate movement control is easy. Become.

  According to the third aspect of the present invention, the same effect as that of the second aspect of the invention can be obtained, and guide means for guiding the linear movement of the lens support is provided. The lens support can be moved stably.

  According to the lens driving device of the fourth aspect, the same effect as that of the invention of the third aspect can be obtained, and the play of the lens support in the circumferential direction can be ensured with a very simple configuration. Therefore, the linear movement of the lens support can be realized reliably and satisfactorily. Further, since the shaft is common to each lens support, the entire lens driving device can be made compact compared to the case where a shaft is individually provided for each lens support.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 is a longitudinal sectional view of the linear drive device according to the present embodiment, FIG. 2 is an exploded perspective view of the linear drive device according to the present embodiment, and FIG. 3A is a view with one yoke removed. The figure which looked at the assembly of the lens drive device of an embodiment from the top, (b) is the figure which looked at the complete assembly of the lens drive device of this embodiment from the top.

  As can be seen from these drawings, the lens driving device 1 according to the present embodiment includes a pair of cylindrical yokes 2 and 4 having a U-shaped cross section facing each other and joined in the axial direction. In the cylindrical space formed by these yokes, there are three annular first, second and third magnets 6, 8, 8 arranged apart from each other along the axial direction of the yokes 2, 4. 10 are accommodated coaxially with each other. In this case, the magnets 6, 8, and 10 are spaced apart in the axial direction at equal distances. The magnets 6, 8, and 10 are fixed to the inner surfaces of the yokes 2 and 4, and their upper surfaces are set to N poles and their lower surfaces are set to S poles. Of course, the magnetic pole setting may be reversed, but the magnetic pole setting on the upper surface and the lower surface is the same for any of the magnets 6, 8, and 10.

  Between the 1st magnet 6 and the 2nd magnet 8, the cylindrical 1st lens support body 12 which hold | maintains the annular | circular shaped 1st coil 20 on the outer periphery is arrange | positioned so that a movement is possible. Further, between the second magnet 8 and the third magnet 10, a cylindrical second lens support 14 that is formed by holding an annular second coil 22 on its outer periphery is movably disposed. Therefore, the first lens support 21 is linearized by an electromagnetic force (following the so-called right-handed screw law) induced by the current flowing through the first coil 20 and the magnetic field formed by the first magnet 6 and the second magnet 8. On the other hand, the second lens support 14 is linearly driven by the electromagnetic force induced by the current flowing through the second coil 22 and the magnetic field formed by the second magnet 8 and the third magnet 10. Can move. Spacers 26 and 28 are interposed between the lens supports 12 and 14 and the first and third magnets 6 and 10, respectively. Each lens support 12, 14 holds a lens 40.

  In the present embodiment, guide means for guiding the linear movement of the lens supports 12 and 14 is provided. Specifically, the guide means includes a pair of shafts 30 and 32 that are provided in common to the two lens supports 12 and 14 and penetrate the lens supports 12 and 14 in the axial direction. In this case, each of the shafts 30 and 32 has a pair of through holes 12a and 12a; 14a and 14a provided in the lens supports 12 and 14 and a pair of through holes 26a and 26a; 28a and 28a of the spacers 26 and 28, respectively. And extends in the axial direction.

  As described above, according to the lens driving device 1 of the present embodiment, two magnetic field spaces are formed in the cylindrical yokes 2, 4 by the three annular magnets 6, 8, 10 arranged coaxially. In addition to being formed adjacent to each other in the axial direction, two cylindrical lens supports 12 and 14 are individually associated with each magnetic field space and individually moved. Therefore, linear movement of the pair of lenses can be realized with a very compact configuration. In addition, since the inside of the yokes 2 and 4 is divided in the axial direction and the magnetic field space for moving the lens supports 12 and 14 is formed separately, both the lens supports 12 and 14 are moved simultaneously. Even so, the influence on the coils 20 and 22 due to repulsion of the magnetic force or the like can be minimized. That is, for example, when two lens supports are moved simultaneously in a common magnetic field space, the movement of the two lens supports is hindered by the magnetic interaction between the coils. Such a problem can be minimized if the magnetic field space in which the magnetic field is moved is separately formed.

  Further, in the above configuration, since the pair of lens supports 12 and 14 are arranged apart from each other along the optical axis direction, the zoom lens and the focus lens are supported on each lens support, respectively. In addition, a compact lens driving device having an automatic focusing mechanism and a magnification changing function can be efficiently realized.

  Further, since the lens 40 moves linearly in the optical axis direction by the electromagnetic force generated by energizing the coils 20 and 22, the direction of the thrust and the direction of movement of the lens coincide with each other, so that the drive loss is extremely small. As a result, the moving speed of the lens 40 can be increased and the responsiveness can be improved. That is, since the drive loss is small and the response and mobility are excellent, the lens 40 can be efficiently moved by a desired amount in the optical axis direction in a narrow space, which is suitable for mounting on a small camera. .

  In the present embodiment, since the three magnets 6, 8, and 10 are axially separated from each other by an equal distance, the attenuation of electromagnetic force accompanying the movement of the lens supports 12 and 14 can be minimized. it can. That is, two lens supports are formed in one magnetic field space formed by the first magnet 6 and the third magnet 10 without arranging the second magnet 8 between the first magnet 6 and the third magnet 10. When the distances 12 and 14 are moved, the electromagnetic force acting on the lens supports 12 and 14 decreases as the distance from the magnets 6 and 10 increases, making it difficult to perform accurate movement control. However, if the second magnet 8 is arranged with an equal distance between the first magnet 6 and the third magnet 10 (in the center between the first magnet 6 and the third magnet 10), the lens supports 12 and 14 are moved. Since the accompanying attenuation of electromagnetic force can be minimized, accurate movement control is facilitated.

  In the present embodiment, since the guide means for guiding the linear movement of the lens supports 12 and 14 is provided, the lens support can be moved stably. In particular, in the present embodiment, the guide means includes a pair of shafts 30 and 32 that are provided in common to the two lens supports 12 and 14 and penetrate the lens supports 12 and 14 in the axial direction. With a very simple configuration, the rattling of the lens supports 12 and 14 in the circumferential direction can be reliably prevented, and the linear movement of the lens supports 12 and 14 can be realized reliably and satisfactorily.

  Further, since the shafts 30 and 32 are common to the lens supports 12 and 14, the entire lens driving device is made compact as compared with the case where the shafts are individually provided for the lens supports 12 and 14, respectively. be able to.

  Needless to say, the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the scope of the invention. For example, in the lens driving device of the above-described embodiment, it is preferable that the lens support is held movably by a spring or the like because the stability of the lens support is further increased. In the embodiment described above, the housing space for the magnets 6, 8, 10 and the lens support bodies 12, 14 is formed by the two separate yokes 2, 4. An accommodation space for the magnet and the lens support may be formed by using a single yoke having the above-described form.

1 is a longitudinal sectional view of a linear drive device according to a first embodiment of the present invention. It is a disassembled perspective view of the linear drive device of FIG. 1A is a view of the lens drive device assembly of FIG. 1 as viewed from above with one yoke removed, and FIG. 1B is a view of the complete assembly of the lens drive device of FIG. 1 as viewed from above. is there.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Linear drive device 2, 4 Yoke 6, 8, 10 Magnet 12, 14 Lens support body 20, 22 Coil

Claims (4)

A cylindrical yoke,
Three annular first, second, and third magnets that are coaxially housed in the yoke and spaced apart from each other along the axial direction of the yoke;
A cylindrical first lens support body that is movably disposed between the first magnet and the second magnet, and that holds an annular first coil on its outer periphery;
A cylindrical second lens support that is movably disposed between the second magnet and the third magnet, and that holds an annular second coil on its outer periphery;
The first lens support is linearly moved by the electromagnetic force induced by the current passed through the first coil and the magnetic field formed by the first magnet and the second magnet,
The lens driving device, wherein the second lens support is linearly moved by an electromagnetic force induced by a current flowing through the second coil and a magnetic field formed by the second magnet and the third magnet.   The lens driving device according to claim 1, wherein the three magnets are spaced apart from each other in the axial direction by an equal distance.   3. The lens driving device according to claim 1, further comprising guide means for guiding linear movement of the lens support. 4. The lens driving device according to claim 3, wherein the guide means includes at least one shaft that is provided in common to the two lens supports and penetrates the lens supports in the axial direction.

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