Lens drive device and lens barrel having same

Abstract

This lens drive device (10) comprises a five-group unit (20), magnetic field units (33a, 33b), and coils (25a-25d). The five-group unit (20) can move back and forth in the optical axis direction. The magnetic field units (33a, 33b) are disposed along the optical axis direction. The coils (25a, 25b) have winding axes disposed along a direction substantially orthogonal to the optical axis, and are disposed at positions facing the magnetic field unit (33a) in the five-group unit (20). The coils (25c, 25d) have winding axes disposed along a direction substantially orthogonal to the optical axis, are disposed at positions facing the magnetic field unit (33b) in the five-group unit (20), and are disposed at positions shifted in the optical axis direction in the five-group unit (20) with respect to the coils (25a, 25b).

Description

Lens driving device and lens barrel including the same

[0001] The present disclosure relates to, for example, a lens driving device that drives, in an optical axis direction, a lens frame holding a lens included in a lens barrel, and to a lens barrel including the same.

[0002] Conventionally, linear motors capable of high-speed response have been used to move a lens frame of a lens barrel in the optical axis direction. For example, Patent Document 1 discloses a lens barrel including a first lens frame that holds a first lens, and a second lens frame that holds a second lens and a third lens and is fitted inside the first lens frame, wherein the first lens frame includes a first holding portion that holds the first lens, and a fitting recess formed around the first holding portion to fit and hold the second lens frame with a predetermined gap therebetween, and the second lens frame includes a second holding portion formed on a side facing the first lens in the optical axis direction to hold the second lens, and a third holding portion formed on an opposite side to the second holding portion in the optical axis direction to fit and hold the third lens with a predetermined gap therebetween.

[0003] Japanese Unexamined Patent Publication No. 2008-111932

[0004] However, the above conventional lens barrel has the following problems. That is, in the lens barrel disclosed in the above publication, coils arranged radially outward of the optical axis in a moving frame that holds a lens are arranged at substantially the same position in the optical axis direction. For this reason, in a lens barrel including a plurality of moving frames driven back and forth in the optical axis direction, there has been a problem that the degree of freedom in design for arranging components is low.

[0005] The object of this disclosure is to provide a lens drive device and a lens barrel equipped therewith that can improve the degree of design freedom compared to the conventional. (Means for solving the problem) The lens drive device according to this disclosure comprises a first moving frame, a first field section and a second field section, a first coil and a second coil. The first moving frame is movable back and forth in the optical axis direction. The first field section and the second field section are arranged along the optical axis direction. The first coil has a winding axis arranged along a direction substantially perpendicular to the optical axis and is positioned opposite the first field section in the first moving frame. The second coil has a winding axis arranged along a direction substantially perpendicular to the optical axis and is positioned opposite the second field section in the first moving frame, and is positioned offset from the first coil in the optical axis direction in the first moving frame. (Effects of the invention) The lens drive device according to this disclosure can improve the degree of design freedom compared to the conventional.

[0006] Figure 7A shows an overall perspective view of a video camera equipped with a lens drive device and lens barrel according to one embodiment of the present disclosure. Figure 1 shows an overall perspective view of the lens barrel included in the video camera. Figure 2 shows an exploded perspective view of the lens barrel. Figure 3 shows a partial cross-sectional perspective view of the field unit constituting the lens drive device included in the lens barrel. Figure 3 shows an exploded perspective view of the 4-group unit included in the lens barrel. Figure 3 shows an exploded perspective view of the 5-group unit included in the lens barrel. Figure 6 shows a front view of the 5-group unit as seen from the optical axis direction. Figure 7A shows a side view. Figure 7A shows a cross-sectional view along line A-A. Figure 3 shows an exploded perspective view of the 6-group unit included in the lens barrel. Figure 3 shows a circuit diagram showing the circuit configuration of a two-phase linear lens drive device included in the lens barrel. Figure 7C shows a schematic diagram showing the positional relationship between the two upper coils A and B included in the 5-group unit and the magnet of the field unit. Figure 7C shows a graph representing the relationship between phase (coil movement amount converted to electrical angle) and the thrust constants of the two upper coils A and B. A graph showing the drive current waveform (pseudo-sine wave) with phase aligned with Figure 11A. A graph showing the relationship between phase and thrust in Figure 11B. A comparative example graph showing the relationship between phase (coil displacement converted to electrical angle) and the thrust constants of the two lower coils C and D in Figure 7C, in a configuration where the two upper coils A and B and the two lower coils C and D are positioned at approximately the same position in the optical axis direction. A comparative example graph showing the drive current waveform (pseudo-sine wave) with phase aligned with Figure 12A. A comparative example graph showing the relationship between phase and thrust in Figure 12B. A schematic diagram showing the positional relationship between the two lower coils C and D, which are fixed at a position shifted by 45 degrees in electrical angle relative to the two upper coils A and B in Figure 10, and the magnet of the field unit. A schematic diagram showing the positional relationship between the two lower coils C and D, which are fixed at a position shifted by 90 degrees in electrical angle relative to the two upper coils A and B in Figure 10, and the magnet of the field unit. A graph showing the relationship between the phase (coil displacement converted to electrical angle) and the thrust constants of the two lower coils in Figure 7C in the configuration of Figure 14A. A schematic diagram showing the positional relationship between the two lower coils C and D, which are fixed at a position shifted by 180 degrees in electrical angle relative to the two upper coils A and B in Figure 10, and the magnets of the field unit. A graph showing the relationship between the phase (coil displacement converted to electrical angle) and the thrust constants of the two lower coils in Figure 7C in the configuration of Figure 15A.A schematic diagram showing the positional relationship between the two lower coils C and D, fixed at a position shifted by 270 degrees in electrical angle relative to the two upper coils A and B in Figure 10, and the magnets of the field unit. A graph showing the relationship between the phase (coil displacement in electrical angle) and the thrust constants of the two lower coils C and D in Figure 7C in the configuration of Figure 16A. A schematic diagram showing the positional relationship between the two lower coils C and D, fixed at a position shifted by 360 degrees in electrical angle relative to the two upper coils A and B in Figure 10, and the magnets of the field unit. A graph showing the relationship between the phase (coil displacement in electrical angle) and the thrust constants of the two lower coils C and D in Figure 7C in the configuration of Figure 17A. A schematic diagram showing the positional relationship between the two lower coils C and D, fixed at a position shifted by 450 degrees in electrical angle relative to the two upper coils A and B in Figure 10, and the magnets of the field unit. A graph showing the relationship between the phase (coil displacement converted to electrical angle) and the thrust constants of the two lower coils C and D in Figure 7C, in the configuration of Figure 18A. A front view of the lens barrel of Figure 1, seen from the subject side in the optical axis direction. A cross-sectional view along line B-B in Figure 19A. A perspective view showing a field unit and a coil having a winding axis parallel to the optical axis direction, included in a lens drive device according to another embodiment of the present disclosure. A perspective view showing the configuration of a lens drive device equipped with the field unit and coil of Figure 20. A front view of Figure 21A, seen from the optical axis direction. A cross-sectional view along line C-C in Figure 21B. A perspective view showing a lens drive device according to yet another embodiment of the present disclosure, in which a VCM is installed instead of a two-phase linear system. A front view of Figure 22A, seen from the optical axis direction. A cross-sectional view along line D-D in Figure 22B.

[0007] The embodiments will be described in detail below, with reference to the drawings as appropriate. However, unnecessary details may be omitted. For example, detailed explanations of already well-known matters or redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding by those skilled in the art. The applicant provides the accompanying drawings and the following explanation so that those skilled in the art can fully understand this disclosure, and not to limit the subject matter described in the claims.

[0008] (Embodiment 1) The lens drive device 10 and the lens barrel 30 equipped therewith, and the video camera (imaging device) 50 according to one embodiment of the present disclosure will be described below with reference to Figures 1 to 19B. (1) Configuration of the video camera 50 The video camera (imaging device) 50 according to this embodiment comprises a lens barrel 30, a camera body 51, and a lens hood 52, as shown in Figure 1.

[0009] The lens barrel 30 is located on the subject side of the camera body 51. The camera body 51 contains an image sensor located at the end of the lens barrel 30 opposite to the subject, which will be described later. The lens hood 52 is attached to the subject side of the lens barrel 30 to eliminate unwanted light entering the lens.

[0010] When the video camera 50 is ready to film a subject, the start shooting button is pressed, which starts exposure to the image sensor mounted on the camera body 51, and the video or image of the subject is recorded on a recording medium or the like. (2) Configuration of the lens barrel 30 As shown in Figure 2, the lens barrel 30 according to this embodiment is configured to guide the light incident from the subject side to the image sensor 39a (see Figure 3) of the image sensor unit 39 via the lens L1, etc.

[0011] As shown in Figure 3, the lens barrel 30 comprises a first group unit (cylindrical member) 31, a second group unit 32, field units (first and second field sections, third field section) 33a, 33b, a third group unit 34, a fourth group unit (second moving frame) 35, a fifth group unit (first moving frame) 20, a sixth group unit (second moving frame) 36, a seventh group unit 37, an IR (Infrared) unit 38, and an image sensor unit 39.

[0012] The first group unit (cylindrical member) 31 holds the first group lens L1 and, as a fixed member, is positioned closest to the subject in the optical axis direction. In addition, as shown in Figure 3, the subject-side ends of two guide shafts 31a and 31b are fixed to the first group unit 31. The two guide shafts 31a and 31b are arranged along the optical axis direction and guide the movement of the movable member (second group unit 32, etc.), which will be described later, in the optical axis direction.

[0013] The second group unit 32 holds the lens L2 and is positioned to be movable back and forth in the optical axis direction. The field units 33a and 33b are components that constitute the lens driving device 10 together with the five group unit 20, which will be described later, and are positioned with their longitudinal direction aligned with the optical axis direction. As shown in Figure 4, the field unit (first field section, third field section) 33a has a magnet 33aa in which the north pole and south pole are alternately arranged in the optical axis direction, and plate-shaped yokes 33ab and 33ac that are positioned to sandwich the magnet 33aa in the radial direction centered on the optical axis.

[0014] As shown in Figure 3, the field unit (second field section, third field section) 33b is positioned on the opposite side of the optical axis from the field unit 33a. As shown in Figure 4, the field unit 33b has a magnet 33aa with N poles and S poles arranged alternately in the direction of the optical axis, and plate-shaped yokes 33ab and 33ac arranged to sandwich the magnet 33aa in the radial direction centered on the optical axis.

[0015] As shown in Figure 4, the magnets 33aa and 33ba have alternating north and south poles arranged along the optical axis. Magnets approximately half the width of the other magnets are attached to both ends of the magnets 33aa and 33ba in the optical axis direction by adhesive bonding. The 3-group unit 34 is a substantially cylindrical member and includes an aperture unit that adjusts the amount of light incident through the lens, and is positioned as a fixed member. In addition, two guide shafts (not shown) are provided on the inner circumferential surface of the 3-group unit 34.

[0016] The two guide axes are provided as guides for the movement of the 4-group unit 35, 5-group unit 20, and 6-group unit 36, which will be described later, back and forth in the optical axis direction on the inner circumferential surface side of the 3-group unit 34. As shown in Figure 3, the 4-group unit (second moving frame) 35 is arranged on the inner circumferential surface side of the substantially cylindrical 3-group unit 34 in a state that allows it to move back and forth in the optical axis direction. As shown in Figure 5, the 4-group unit 35 has a main body portion 35a, a lens holding portion 35b that holds the lens L4, a guide hole 35c into which a guide axis (not shown) provided on the inner circumferential surface side of the 3-group unit 34 is inserted, a coil mounting portion 35d, and a coil (third coil) 35e.

[0017] When current is supplied to the two-phase coils 35e, which are arranged along the optical axis direction on the coil mounting portion 35d of the main body portion 35a, the four-group unit 35 moves in the optical axis direction due to the Lorentz force (electromagnetic force) generated between the coils 35e and the field unit 33b, which is located adjacent to the radially outer side of the coils 35e. Furthermore, the four-group unit 35 is cantilevered so that it moves back and forth in the optical axis direction when current is supplied to the two-phase coils 35e, which are located only on the lower side in the figure on the radially outer side of the optical axis.

[0018] The 5-group unit (first moving frame) 20 is configured to include an OIS (Optical Image Stabilization) unit, and, similar to the 4-group unit 35, is positioned on the inner circumferential surface side of the substantially cylindrical 3-group unit 34 in a manner that allows it to move back and forth in the optical axis direction. As shown in Figure 6, the 5-group unit 20 includes an OIS yoke 21, OIS magnets 22a, 22b, OIS drive magnets 23a, 23b, a 5-group frame 24, coils (first coils) 25a, 25b, coils (second coils) 25c, 25d, an OIS ball 26a, an OIS biasing spring 26b, Hall elements 26ca, 26cb, OIS coils 27a, 27b, an OIS frame 28, and a cover 29.

[0019] As shown in Figure 6, the OIS yoke 21 is a substantially annular plate-shaped member and is positioned furthest towards the subject in the optical axis direction among the members constituting the 5-group unit 20. The OIS yoke 21 is positioned in close proximity to the OIS magnets 22a, 22b and the OIS drive magnets 23a, 23b. The OIS magnets 22a, 22b are positioned between the subject-side surface of the 5-group frame 24 and the OIS yoke 21.

[0020] The OIS drive magnets 23a and 23b are positioned between the subject-facing surface of the 5-group frame 24 and the OIS yoke 21, sandwiching the 5-group frame 24 in the optical axis direction, and facing the OIS coils 27a and 27b, which will be described later. As a result, the 5-group frame 24 to which the OIS drive magnets 23a and 23b are attached can be moved in a plane perpendicular to the optical axis by receiving the Lorentz force (electromagnetic force) generated when the OIS coils 27a and 27b are energized.

[0021] The 5-group frame 24 holds the lens L5 shown in Figure 6 and is positioned to be movable on a plane perpendicular to the optical axis relative to the OIS frame 28. The 5-group frame 24 moves back and forth in the optical axis direction by receiving the Lorentz force (electromagnetic force) generated between it and the field units 33a and 33b when current is passed through the coils 25a, 25b, 25c, and 25d. As shown in Figures 7A and 7B, the 5-group frame 24 has a main body portion 24a, a lens holding portion 24b, a guide hole 24c, and coil mounting portions 24da and 24db.

[0022] The main body portion 24a is provided with a lens holding portion 24b for holding the lens L5, a guide hole 24c into which a guide shaft (not shown) provided on the inner circumferential surface side of the 3-group unit 34 is inserted, and coil mounting portions 24da and 24db on which coils 25a, 25b and coils 25c, 25d are placed, respectively. The lens holding portion 24b is provided in the approximate center of the main body portion 24a and holds the lens L5.

[0023] The guide hole 24c is into which one of two guide shafts (not shown) provided on the inner circumferential surface side of the 3-group unit 34 is inserted. The coil mounting sections 24da and 24db are located on the upper and lower parts of the main body section 24a, respectively. Coils 25a and 25b are placed in the coil mounting section 24da, and coils 25c and 25d are placed in the coil mounting section 24db.

[0024] The coils (first coils) 25a and 25b have winding axes arranged in a direction substantially perpendicular to the optical axis and are positioned opposite the field unit 33a in the 5-group unit 20. As shown in Figure 6, the coils 25a and 25b are attached to the upper side of the 5-group frame 24 and receive the Lorentz force (electromagnetic force) generated between them and the aforementioned field unit 33a when energized.

[0025] The coils (second coils) 25c and 25d have winding axes arranged in a direction substantially perpendicular to the optical axis and are positioned opposite the field unit 33b in the 5-group unit 20. Furthermore, as shown in Figure 7C, coils 25c and 25d are positioned offset from coils 25a and 25b in the optical axis direction in the 5-group unit 20 (see dashed circle in Figure 7C). In addition, as shown in Figure 6, coils 25c and 25d are attached to the lower side of the 5-group frame 24 and receive the Lorentz force (electromagnetic force) generated between them and the aforementioned field unit 33b when energized.

[0026] As shown in Figure 6, the OIS ball 26a is positioned between the subject-side surface of the OIS frame 28 and the opposing surface of the 5-group frame 24, and rolls on the opposing surface of the 5-group frame 24. The OIS biasing spring 26b is also positioned between the subject-side surface of the OIS frame 28 and the opposing surface of the 5-group frame 24, as shown in Figure 6. The OIS biasing spring 26b applies a biasing force in the optical axis direction, pulling the 5-group frame 24 towards the OIS frame 28.

[0027] The Hall elements 26ca and 26cb are provided as position sensors together with the OIS magnets 22a and 22b to detect the position of the 5-group frame 24 on a plane perpendicular to the optical axis relative to the OIS frame 28. The OIS coils 27a and 27b are attached to the OIS frame 28 as shown in Figure 6, and when energized, they generate a Lorentz force (electromagnetic force) between them and the OIS drive magnets 23a and 23b. As a result, the Lorentz force (electromagnetic force) generated when the OIS coils 27a and 27b are energized allows the 5-group frame 24 to which the OIS drive magnets 23a and 23b are attached to be moved in a plane perpendicular to the optical axis.

[0028] As shown in Figure 6, the OIS frame 28 is a substantially annular plate-shaped member to which OIS coils 27a, 27b, Hall elements 26ca, 26cb, etc. are attached. As shown in Figure 6, the cover 29 is a substantially annular plate-shaped member and is positioned on the side furthest from the subject in the optical axis direction among the members constituting the 5-group frame 24. In the lens drive device 10 of this embodiment, as shown in Figure 7C, in the 5-group unit 20, the coils 25a, 25b and coils 25c, 25d, which are provided on the upper and lower parts of the 5-group frame 24 respectively, are positioned at offset positions (different positions) in the optical axis direction.

[0029] Here, for example, if we assume that the upper and lower coils 25a, 25b and coils 25c, 25d are positioned at approximately the same location in the optical axis direction, the lower coils 25c, 25d will interfere with the coil mounting portion 35d of the 4-group unit 35, and the upper coils 25a, 25b will interfere with the coil mounting portion 36d of the 6-group unit 36. In the lens drive device 10 of this embodiment, by positioning the upper and lower coils 25a, 25b and coils 25c, 25d, which drive the 5-group unit 20 back and forth in the optical axis direction, at offset positions (different positions) in the optical axis direction, interference between components within the lens barrel 30 can be avoided.

[0030] In the lens drive device 10, simply arranging coils 25a, 25b and coils 25c, 25d at offset positions in the optical axis direction may not allow for both linear motor performance and miniaturization. Therefore, in the lens drive device 10 of this embodiment, the upper and lower coils 25a, 25b and coils 25c, 25d are arranged according to a certain rule, thereby achieving a configuration that balances linear motor performance and miniaturization.

[0031] The specific principles for achieving both linear motor performance and miniaturization will be described in detail later. The 6-group unit (second moving frame) 36 includes a focus lens (lens L6) and, as shown in Figure 3, is positioned on the inner circumferential surface of the substantially cylindrical 3-group unit 34 in a manner that allows it to move back and forth in the optical axis direction. As shown in Figure 8, the 6-group unit 36 ​​has a main body portion 36a, a lens holding portion 36b that holds the lens L6, a guide hole 36c into which a guide shaft (not shown) provided on the inner circumferential surface of the 3-group unit 34 is inserted, a coil mounting portion 36d, and a coil (third coil) 36e.

[0032] When current is supplied to the two-phase coils 36e, which are arranged along the optical axis direction on the coil mounting portion 36d of the main body portion 36a, the 6-group unit 36 ​​moves in the optical axis direction due to the Lorentz force (electromagnetic force) generated between the coils 36e and the field unit 33a, which is located adjacent to the radially outer side of the coils 36e. Furthermore, the 6-group unit 36 ​​is cantilevered so that it moves back and forth in the optical axis direction when current is supplied to the two-phase coils 36e, which are located only on the upper side in the figure on the radially outer side of the optical axis.

[0033] The 7-group unit 37 includes a focus lens (lens L7) and is positioned as a fixed component. The IR unit 38 includes a mechanism for inserting and removing infrared cut glass and is positioned between the 7-group unit 37 and the image sensor unit 39. As shown in Figure 3, the image sensor unit 39 is a roughly plate-shaped component fixed inside the camera body 51 and has an image sensor 39a whose center is positioned on the extension of the optical axis.

[0034] (3) Overall configuration of the lens driving device 10 The lens driving device 10 according to this embodiment is a device that moves the above-described 5-group unit 20 back and forth in the optical axis direction, and comprises the 5-group unit 20, field units 33a, 33b, and coils 25a, 25b, 25c, 25d. The 5-group unit 20 is movable back and forth in the optical axis direction by the Lorentz force (electromagnetic force) generated when current is supplied to coils 25a, 25b and coils 25c, 25d.

[0035] As shown in Figure 3, the field units 33a and 33b are arranged along the optical axis direction at positions opposite to the coils 25a, 25b and coils 25c, 25d, respectively, which are provided in the 5-group unit 20. The coils 25a and 25b have winding axes arranged in a direction substantially perpendicular to the optical axis and are positioned opposite the field unit 33a in the 5-group unit 20.

[0036] Coils 25c and 25d have winding axes arranged along a direction substantially perpendicular to the optical axis and are positioned opposite the field unit 33b in the 5-group unit 20. As shown in Figure 7C, coils 25c and 25d are positioned at offset positions (different positions) in the optical axis direction of the 5-group unit 20 relative to coils 25a and 25b. Here, the lens driving device 10 of this embodiment can also be shown as the driving circuit shown in Figure 9.

[0037] Specifically, as shown in Figure 9, the lens drive device 10 is a two-phase linear drive circuit and includes a circuit 11 for driving coil A (coil 25a) in Figure 10, a circuit 12 for driving coil B (coil 25b) in Figure 10, and a drive field unit 33a positioned close to coils 25a and 25b. The circuit 11 on the coil A side shown in Figure 10 has positive transistors 13a and 13b and negative transistors 14a and 14b.

[0038] The circuit 12 on the coil B side shown in Figure 10 has positive transistors 15a and 15b and negative transistors 16a and 16b. As a result, by alternately turning the positive and negative sides ON / OFF in the circuit 11 on the coil A side and the circuit 12 on the coil B side, the 5-group unit 20, which is provided with coils 25a and 25b, can be driven back and forth in the optical axis direction relative to the driving field unit 33a.

[0039] The relative positions of coil A (coil 25a) and coil B (coil 25b) shown in Figure 7C and the magnetic poles of the field unit 33a are as shown in Figure 10. Furthermore, in the circuit 11 on the coil A side and the circuit 12 on the coil B side, the thrust constant with respect to phase is a sinusoidal graph as shown in Figure 11A. The lens drive device 10 is driven by a drive current waveform (pseudo-sinusoidal wave) as shown in Figure 11B, which is the current waveform with respect to phase.

[0040] Therefore, as a result of combining the graphs in Figures 11A and 11B, coils A and B (coils 25a and 25b) can obtain a substantially constant thrust, as shown by the dashed lines in Figure 11C. In this embodiment, a configuration using two coils 25a and 25b to drive in a two-phase linear manner was illustrated and explained, but a configuration using three coils to drive in a three-phase linear manner may also be used.

[0041] However, in the case of three-phase drive, it is necessary to use three coils arranged in the optical axis direction, and the actuator tends to be longer in the optical axis direction than in the case of two-phase drive, so two-phase drive is more suitable as a linear motor for driving lenses. Now, let's consider coil C (coil 25c) and coil D (coil 25d) shown in Figure 7C.

[0042] As one example, FIG. 13 shows a case where coil C and coil D are fixed at positions shifted by 45 degrees in electrical angle with respect to coil A and coil B. FIG. 12A shows a graph representing changes in the phase (movement amount converted to electrical angle) and the thrust constants of coil C and coil D (coils 25c, 25d) at this time. As shown in FIG. 12A, the changes in thrust constants of coil C and coil D are sinusoidal graphs with a 45-degree phase shift relative to the changes in thrust constants of coil A and coil B shown in FIG. 11A.

[0043] Here, as shown in FIG. 12B, when coil C and coil D are energized with the same current waveform as that applied to coil A and coil B shown in FIG. 11B, as shown in FIG. 12C, the thrust fluctuates at the step switching timing of the pseudo sine wave, and the total thrust also decreases to about 71%. Therefore, in order for the lens driving device to fully exhibit its characteristics as a linear motor, it is necessary to use separate driving circuits for the coils A and B and for the other coils. As a result, the cost of the driving circuit increases, and the volume occupied by the driving circuit also increases, making it difficult to achieve miniaturization.

[0044] To address such a problem, in the lens driving device 10 of the present embodiment, the two lower coils C and D are arranged at positions shifted by a specific dimension in the optical axis direction with respect to the two upper coils A and B. This configuration prevents characteristic degradation even when coils C and D are driven by the same driving circuit as coils A and B. Note that the electrical angle is a value indicating a relative dimension when the dimension of one pair of magnetic poles (N pole and S pole) is defined as 360 degrees.

[0045] Hereinafter, several examples will be given to describe the specific dimension that prevents characteristic degradation even when coils C and D are driven by the same driving circuit as coils A and B. As a first embodiment, as shown in FIG. 14A, coils C and D (coils 25c, 25d) may be arranged at positions shifted by 90 degrees in terms of electrical angle conversion in the optical axis direction with respect to coils A and B (coils 25a, 25b).

[0046] At this time, as shown in FIG. 14B, the thrust waveform of coil C (coil 25c) is identical to the thrust waveform of coil B (coil 25b) shown in FIG. 11A with positive and negative inverted. Therefore, in order to invert the positive and negative of the thrust waveform of coil C (coil 25c), it is sufficient to connect coil C to the drive circuit of coil B (coil 25b) by inverting the winding start and winding end of the coil. Further, in FIG. 14A, the thrust waveform of coil D (coil 25d) is identical to the thrust waveform of coil A (coil 25a) shown in FIG. 11A. Therefore, coil D (coil 25d) may be connected as it is to the drive circuit of coil A (coil 25a).

[0047] Accordingly, even if coils C and D are driven by the same drive circuit as the drive circuit for coils A and B, characteristics can be prevented from deteriorating. Further, as a second embodiment, as shown in FIG. 15A, coils C and D may be arranged at positions shifted from coils A and B (coils 25a and 25b) by 180 degrees in terms of electrical angle conversion in the optical axis direction.

[0048] At this time, the thrust waveform of coil C (coil 25c) shown in FIG. 15B is identical to the thrust waveform of coil A (coil 25a) shown in FIG. 11B with positive and negative inverted. Therefore, in order to invert the positive and negative of the thrust waveform of coil C (coil 25c), it is sufficient to connect coil C to the drive circuit of coil A (coil 25a) by inverting the winding start and winding end of the coil. Further, the thrust waveform of coil D (coil 25d) shown in FIG. 15B is identical to the thrust waveform of coil B (coil 25b) shown in FIG. 11B with positive and negative inverted. Therefore, in order to invert the positive and negative of the thrust waveform of coil D (coil 25d), it is sufficient to connect coil D to the drive circuit of coil B (coil 25b) by inverting the winding start and winding end of the coil.

[0049] Accordingly, even if coils C and D (coils 25c and 25d) are driven by the same drive circuit as the drive circuit for coils A and B (coils 25a and 25b), characteristics can be prevented from deteriorating. Further, as a third embodiment, as shown in FIG. 16A, coils C and D (coils 25c and 25d) may be arranged at positions shifted from coils A and B (coil 25a) by 270 degrees in terms of electrical angle conversion in the optical axis direction.

[0050] In this case, the thrust waveform of coil C (coil 25c) shown in Figure 16B is the same as the thrust waveform of coil B (coil 25b) shown in Figure 11B. Therefore, coil C (coil 25c) can be connected directly to the drive circuit of coil B (coil 25b). Also, the thrust waveform of coil D (coil 25d) is the same as the thrust waveform of coil A (coil 25a) with the polarity reversed. Therefore, in order to reverse the polarity of the thrust waveform of coil D (coil 25d), it is sufficient to connect it to the drive circuit of coil A (coil 25a) with the start and end of the coil reversed.

[0051] This ensures that even when coils C and D (coils 25c and 25d) are driven by the same drive circuit as coils A and B (coils 25a and 25b), their characteristics do not deteriorate. Furthermore, in a fourth embodiment, coils C and D (coils 25c and 25d) may be positioned at a location offset by 360° in terms of electrical angle in the optical axis direction relative to coils A and B (coils 25a and 25b), as shown in Figure 17A.

[0052] In this case, the thrust waveform of coil C (coil 25c) shown in Figure 17B is the same as the thrust waveform of coil A (coil 25a) shown in Figure 11B. Therefore, coil C (coil 25c) can be directly connected to the drive circuit of coil A (coil 25a). Also, the thrust waveform of coil D (coil 25d) shown in Figure 17B is the same as the thrust waveform of coil B (coil 25b). Therefore, coil D (coil 25d) can be directly connected to the drive circuit of coil B (coil 25b).

[0053] This ensures that even when coils C and D (coils 25c and 25d) are driven by the same drive circuit as coils A and B (coils 25a and 25b), their characteristics do not deteriorate. Furthermore, in a fifth embodiment, coils C and D (coils 25c and 25d) may be positioned relative to coils A and B (coil 25a) at a position offset by, for example, 450° in terms of electrical angle in the optical axis direction, as shown in Figure 18A.

[0054] In this case, the thrust waveform of coil C (coil 25c) shown in Figure 18B is the same as the thrust waveform of coil C (coil 25c) shown in Figure 14B. Therefore, coil C (coil 25c) can be connected to the drive circuit of coil B (coil 25b) with the beginning and end of the coil reversed, similar to the first embodiment shown in Figure 14B. Also, the thrust waveform of coil D (coil 25d) shown in Figure 18B is the same as the thrust waveform of coil D (coil 25d) shown in Figure 14B. Therefore, similar to the first embodiment shown in Figure 14B, coil D (coil 25d) can be connected directly to the drive circuit of coil A (coil 25a).

[0055] As a result, even when coils C and D (coils 25c and 25d) are driven by the same drive circuit as coils A and B (coils 25a and 25b), their characteristics will not deteriorate. As described above, in the lens drive device 10 of this embodiment, there is an optimal arrangement for coils C and D (coils 25c and 25d) at 90° intervals in terms of electrical angle relative to coils A and B (coils 25a and 25b).

[0056] Here, we have described the case where the lens drive device 10 is a two-phase linear motor, but in the case of a three-phase linear motor, there is an optimal position every 60 degrees. Generally, when the linear motor is n-phase, the coil facing the first field section and the coil facing the second field section are fixed at positions that are angularly shifted by 180 × k / n (°) in terms of electrical angle in the optical axis direction, so that the characteristics do not deteriorate even when driven by the same drive circuit. (n is an integer of 2 or more, k is an integer of 1 or more) <Main Features> As shown in Figure 6, the lens drive device 10 of this embodiment comprises a five-group unit 20, field units 33a and 33b, and coils 25a to 25d. The five-group unit 20 is movable back and forth in the optical axis direction. The field units 33a and 33b are arranged along the optical axis direction. Coils 25a and 25b have winding axes arranged along a direction substantially perpendicular to the optical axis and are positioned opposite the field unit 33a in the 5-group unit 20. Coils 25c and 25d, as shown in Figure 7C, have winding axes arranged along a direction substantially perpendicular to the optical axis and are positioned opposite the field unit 33b in the 5-group unit 20, and are positioned offset from coils 25a and 25b in the optical axis direction in the 5-group unit 20.

[0057] This makes it possible to design a lens barrel 30, which includes multiple movable frames (a 4-group unit 35, a 5-group unit 20, and a 6-group unit 36) that are driven back and forth in the optical axis direction, in a way that minimizes size in the optical axis direction while avoiding interference with each other. As a result, the degree of design freedom can be improved compared to conventional designs. Furthermore, in the lens drive device 10 of this embodiment, as shown in Figures 19A and 19B, the coils 35e and 36e included in the 4-group unit 35 and the 6-group unit 36, which are arranged to be movable to positions adjacent to the 5-group unit 20 in the optical axis direction, are positioned in a way that overlaps with the coils 25a, 25b, 25c, and 25d of the 5-group unit 20 in the optical axis direction.

[0058] As a result, the 4-group unit 35 and the 6-group unit 36, which are positioned adjacent to the 5-group unit 20 and can move back and forth in the optical axis direction, are driven by a single coil 35e, 36e, respectively, thereby reducing the size in the optical axis direction and improving the degree of design freedom. (Embodiment 2) A lens driving device 110 according to another embodiment of the present disclosure will be described below with reference to Figures 20 to 21C.

[0059] Furthermore, the lens drive device 110 of this embodiment differs from the configuration of Embodiment 1, which uses coils 25a and 25b whose winding axes are substantially perpendicular to the optical axis direction, in that the winding axes of the coils 125a and 125b fixedly arranged in the 5-group unit 20 are arranged substantially parallel to the optical axis direction. For the sake of convenience of explanation, components having the same function and shape as those described in the above embodiment are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0060] As shown in Figure 20, the lens drive device 110 of this embodiment includes a cover 111, movable rods (first field section, second field section) 133a, 133b, and coils 125a, 125b. The movable rod (first field section) 133a is arranged along the optical axis direction and is configured such that the north pole and south pole are alternately arranged in the optical axis direction.

[0061] The movable rod (second field section) 133b is arranged along the optical axis direction, similar to the movable rod 133a, and is configured so that north poles and south poles are alternately arranged in the optical axis direction. The magnets included in the movable rods 133a and 133b are magnetized in the optical axis direction and arranged alternately with the same magnetic poles facing each other.

[0062] The movable rods 133a and 133b are fixed at both ends by the 1-group unit 31 and the 7-group unit 37, similar to the field units 33a and 33b in Embodiment 1 described above, and their outer circumference is covered by the cover 111. The coil (first coil) 125a is arranged to wind around the outer circumference of the movable rod 133a, as shown in Figures 21A to 21C, and its winding axis is substantially parallel to the optical axis direction. The coil 125a is fixed to the 5-group frame 24 of the 5-group unit 20, and the Lorentz force (electromagnetic force) generated by the energization causes the 5-group unit 20 to move back and forth in the optical axis direction.

[0063] As shown in Figures 21A to 21C, the coil (second coil) 125b is arranged to wind around the outer circumference of the movable rod 133b, and its winding axis is approximately parallel to the optical axis direction. Coil 125b is fixed to the opposite side of the optical axis from coil 125a in the 5-group unit 20, and the Lorentz force (electromagnetic force) generated by the current causes the 5-group unit 20 to move back and forth in the optical axis direction. Furthermore, coil 125b is positioned offset from coil 125a in the optical axis direction.

[0064] As a result, the lens drive device 110 of this embodiment can drive the 5-group unit 20 back and forth in the optical axis direction, similar to Embodiment 1 above. Furthermore, since the coils 125a and 125b are arranged at offset positions in the optical axis direction, miniaturization in the optical axis direction can be achieved, similar to Embodiment 1 above, and the degree of design freedom can be improved. [Other Embodiments] Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the gist of the disclosure.

[0065] (A) In the above embodiment, a linear motor comprising n-phase coils 25a, 25b and field units 33a, 33b including N poles and S poles arranged alternately along the optical axis was described as the lens driving device 10 of the present disclosure. However, the present disclosure is not limited thereto.

[0066] For example, instead of the n-phase coils 25a, 25b and field units 33a, 33b, a lens drive device 210 as a VCM (Voice Coil Motor) may be used, as shown in Figures 22A, 22B, and 22C. As shown in Figures 22A to 22C, the lens drive device 210 has a coil (first coil) 225a and a coil (second coil) 225b and a yoke (first field section) 233a and a yoke (second field section) 233b, respectively, which are provided on the upper and lower parts of the 5-group frame 24 so as to sandwich the lens L5.

[0067] The coils 225a and 225b are wound around the center yoke of the yokes 233a and 233b so as to cover a portion of the center yoke, and move along the longitudinal direction (optical axis direction) of the center yoke. The coils 225a and 225b are positioned offset in the optical axis direction, as shown in Figure 22C, similar to embodiments 1 and 2 described above. The yokes 233a and 233b are formed by stamping out laminated iron sheet metal using a press. The yokes 233a and 233b have a roughly U-shaped main yoke, a center yoke attached to the central part of the roughly U-shaped main yoke approximately parallel to the two arm portions, and a sub-yoke attached to the roughly U-shaped open end of the main yoke.

[0068] Furthermore, magnets are positioned on the inner surfaces of the two arms of the roughly U-shaped main yoke. The magnets are, for example, Nd-based sintered magnets, and each is unipolarally magnetized. In this way, even with a configuration in which a VCM is installed instead of n-phase coils and field units, the same effects as the above-described configuration can be obtained.

[0069] (B) In the above embodiment, an example was given in which the 5-group unit 20 is driven back and forth in the optical axis direction using two-phase coils 25a and 25b. However, the disclosure is not limited thereto. For example, instead of two-phase coils, a configuration may be used in which three or more phase coils are used to drive the first moving frame (5-group unit 20) back and forth in the optical axis direction.

[0070] (C) In the above embodiment, an example in which the lens drive device 10 according to the present disclosure is applied to a 5-group unit 20 has been described. However, the present disclosure is not limited thereto. For example, the lens drive device according to the present disclosure may be applied to other moving frames.

[0071] (D) In ​​the above embodiment, an example was described in which a 4-group unit 35 and a 6-group unit 36, which are cantilevered and movable in the optical axis direction, are arranged as a second moving frame on both sides of the 5-group unit 20 in the optical axis direction as a first moving frame. However, the present disclosure is not limited thereto.

[0072] For example, a configuration may be in which a cantilevered second moving frame is positioned on only one side of the first moving frame in the optical axis direction. (E) In the above embodiment, an example was given in which the lens driving device 10 according to the present disclosure is mounted on the lens barrel 30 of a video camera 50. However, the present disclosure is not limited thereto.

[0073] For example, the lens drive device according to this disclosure may be mounted on a lens barrel that is attached to a camera body in a manner that is detachable or indetachable, rather than on a video camera. <Note> The above description of embodiments discloses the following technologies. (Technology 1) The lens drive device according to Technology 1 comprises: a first movable frame that is movable back and forth in the optical axis direction; a first field section and a second field section arranged along the optical axis direction; a first coil having a winding shaft arranged along a direction substantially perpendicular to the optical axis and positioned opposite the first field section in the first movable frame; and a second coil having a winding shaft arranged along a direction substantially perpendicular to the optical axis and positioned opposite the second field section in the first movable frame, and positioned offset from the first coil in the optical axis direction in the first movable frame.

[0074] (Technology 2) The lens driving device according to Technology 2 is the lens driving device according to Technology 1, wherein the first field section and the second field section have N poles and S poles arranged alternately along the optical axis direction. (Technology 3) The lens driving device according to Technology 3 is the lens driving device according to Technology 1 or 2, wherein the first coil and the second coil are each provided as n-phase coils arranged side by side along the optical axis direction. (n is an integer of 2 or more) (Technology 4) The lens driving device according to Technology 4 is the lens driving device according to Technology 3, wherein the first coil and the second coil are fixed at positions shifted by 180 × k / n (°) in terms of electrical angle in the optical axis direction. (k is an integer of 1 or more) (Technology 5) The lens driving device according to Technology 5 is a lens driving device according to any one of Technologies 1 to 4, further comprising: a second moving frame positioned adjacent to the first moving frame in the optical axis direction; a third magnetic field section positioned along the optical axis direction; and a third coil having a winding shaft positioned in a direction substantially perpendicular to the optical axis and positioned opposite the third magnetic field section in the second moving frame.

[0075] (Technology 6) The lens driving device according to Technology 6 is the lens driving device according to Technology 5, wherein the third coil is positioned in a location that overlaps with the first coil or the second coil in the optical axis direction. (Technology 7) The lens driving device according to Technology 7 is the lens driving device according to any one of Technologies 1 to 6, wherein the first coil and the second coil each have a winding axis substantially perpendicular to the optical axis.

[0076] (Technology 8) The lens driving device according to Technology 8 is a lens driving device according to any one of Technologies 1 to 6, wherein the first coil and the second coil each have a winding axis substantially parallel to the optical axis.

[0077] (Technology 9) The lens barrel according to Technology 9 comprises a lens driving device according to any one of Technologies 1 to 8, and a cylindrical member enclosing the lens driving device.

[0078] The lens driving device of this disclosure has the effect of improving the degree of design freedom compared to conventional devices, and is therefore widely applicable to various devices that drive optical lenses in the optical axis direction.

[0079] 10 Lens driving device 11 Circuit 12 Circuit 13a, 13b Transistors 14a, 14b Transistors 15a, 15b Transistors 16a, 16b Transistors 20 5-group unit (first moving frame) 21 OIS yoke 22a, 22b OIS magnet 23a, 23b OIS driving magnet 24 5-group frame 24a Main body 24b Lens holding part 24c Guide hole 24da, 24db Coil mounting part 25a Coil (first coil, coil A) 25b Coil (first coil, coil B) 25c Coil (second coil, coil C) 25d Coil (second coil, coil D) 26a OIS ball 26b OIS biasing spring 26ca, 26cb Hall element 27a, 27b OIS coil 28 OIS frame 29 Cover 30 Lens barrel 31 1st group unit (cylindrical member) 31a, 31b Guide shaft 32 2nd group unit 33a Field unit (first field section, third field section) 33aa Magnet 33ab, 33ac Yoke 33b Field unit (second field section, third field section) 33ba Magnet 34 3rd group unit 35 4th group unit (second moving frame) 35a Main body 35b Lens holder 35c Guide hole 35d Coil mounting section 35e Coil (third coil) 36 6th group unit (second moving frame) 36a Main body 36b Lens holder 36c Guide hole 36d Coil mounting section 36e Coil (third coil) 37 7th group unit 38 IR unit 39 Image sensor unit 39a Image sensor 50 Video camera 51 Camera body 52 Lens hood 110 Lens drive device 111 Cover 125a Coil (first coil) 125b Coil (second coil) 133a Movable rod (first field section) 133b Movable rod (second field section) 210 Lens drive device 225a Coil (first coil) 225b Coil (second coil) 233a Yoke (first field section) 233b Yoke (second field section) L1, L2, L3, L4, L5, L6, L7 Lens

Claims

1. A lens drive device comprising: a first movable frame that is movable back and forth in the optical axis direction; a first field section and a second field section arranged along the optical axis direction; a first coil having a winding axis arranged in a direction substantially perpendicular to the optical axis and positioned opposite the first field section in the first movable frame; and a second coil having a winding axis arranged in a direction substantially perpendicular to the optical axis and positioned opposite the second field section in the first movable frame, and positioned offset from the first coil in the optical axis direction in the first movable frame.

2. The lens driving device according to claim 1, wherein the first field section and the second field section have N poles and S poles arranged alternately along the optical axis direction.

3. The lens driving device according to claim 1 or 2, wherein the first coil and the second coil are each provided as n-phase coils arranged side by side along the optical axis direction. (n is an integer of 2 or more) 4. The lens driving device according to claim 3, wherein the first coil and the second coil are fixed at positions offset by 180 × k / n (°) in terms of electrical angle in the optical axis direction. (k is an integer of 1 or more) 5. The lens drive device according to claim 1 or 2, further comprising: a second moving frame positioned adjacent to the first moving frame in the optical axis direction; a third magnetic field section positioned along the optical axis direction; and a third coil having a winding axis positioned in a direction substantially perpendicular to the optical axis and positioned opposite the third magnetic field section in the second moving frame.

6. The lens driving device according to claim 5, wherein the third coil is positioned in a location that overlaps with the first coil or the second coil in the optical axis direction.

7. The lens driving device according to claim 1 or 2, wherein the first coil and the second coil each have a winding axis substantially perpendicular to the optical axis.

8. The lens driving device according to claim 1 or 2, wherein the first coil and the second coil each have a winding axis substantially parallel to the optical axis.

9. A lens barrel comprising: a lens driving device according to claim 1 or 2; and a cylindrical member enclosing the lens driving device.

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