JP2016157031A - Lens driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens driving device in which a stepping motor having a sensor using a magnetic sensor and a sensor magnet is mounted, and its lens barrel and imaging device can be miniaturized while lowering a disturbance magnetic field to the magnetic sensor, and which is capable of further accurate position detection.SOLUTION: The stepping motor having a sensor includes a lens holding frame and a fixing section, and drives the lens holding frame relative to the fixing section. The stepping motor is composed of an actuator unit, a U-shaped sheet metal, and a sensor unit having the sensor magnet and the magnetic sensor. The sensor unit is arranged inside the U-shaped sheet metal, and the magnetic sensor is positioned between the U-shaped sheet metal and the sensor magnet.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lens barrel used in an imaging device such as a digital video camera or a digital still camera, and more particularly to a lens driving device for realizing zooming or a focusing function.

  Conventionally, in a lens barrel such as a digital video camera or a digital still camera, a lens driving device that drives a moving lens group using a stepping motor is mounted. As a control method for driving a lens group at a particularly high speed with this lens driving device, a lens driving device for providing a stepping motor with a sensor for detecting the rotation angle of the stepping motor and performing advance angle control for controlling the timing of excitation to the stepping motor. Has been proposed.

  Patent Document 1 discloses a configuration in which a coupling portion with a driven body is provided between a magnetic sensor of a stepping motor and an actuator. Patent Document 2 discloses a configuration in which a magnetic sensor of a stepping motor is disposed at a substantially symmetrical position of a magnetic circuit having another group. This is a technique for reducing the influence of a disturbance magnetic field by arranging a magnetic sensor at a position where there is almost no magnetic field component in a predetermined direction detected by a magnetic sensor among magnetic fields generated by magnetic circuits of other groups.

JP 2004-334099 A JP 2000-227614 A

  A recent lens barrel is equipped with a plurality of actuators such as an anti-vibration mechanism, a focus mechanism, a zoom mechanism, an aperture mechanism, and a shutter mechanism. Therefore, there are cases where there are a plurality of parts that generate a magnetic field that becomes a disturbance to the magnetic sensor of the stepping motor, such as magnets and magnetic bodies included in these actuators, a magnetic scale for detecting the position of the moving lens group, and a magnetic sensor. is there. When the magnetic sensor is affected by these disturbance magnetic fields, the accuracy of the position detection of the stepping motor is lowered.

  With respect to this problem, in the conventional technique disclosed in Patent Document 1 described above, when there is another group of drive magnets in the lens barrel, the drive magnets of the other groups are reduced in order to reduce the influence of the disturbance magnetic field. On the other hand, the magnetic sensor can be arranged in the optical axis direction. However, in the longitudinal direction of the stepping motor, when there are a plurality of other groups of magnets on both the front and rear sides of the magnetic sensor, this cannot be handled. Even if an arbitrary magnet and a magnetic sensor can be arranged away from each other, it is difficult to isolate the remaining magnets from the magnetic sensor.

  On the other hand, in the conventional technique disclosed in Patent Document 2 described above, when there are a plurality of magnetic circuits having other groups, the combined magnetic circuit is complicated, and it is difficult to calculate the substantially symmetrical position of the combined magnetic circuit. It is. Even if the substantially symmetrical position of the magnetic circuit can be calculated, the degree of freedom in design is reduced by arranging the magnetic sensor in a limited range, and as a result, there is a problem that the lens barrel tends to be enlarged. It was.

  Furthermore, since the above-described conventional technique is a technique for reducing the influence of the disturbance magnetic field by restricting the arrangement, the influence of the disturbance magnetic field is compared with a technique for actively shielding the disturbance magnetic field such as using a shielding plate. Is easy to remain.

  Therefore, the present invention provides a lens driving device equipped with a sensor-equipped stepping motor that uses a magnetic sensor and a sensor magnet, in which the disturbance magnetic field to the magnetic sensor is more than that of the prior art even if a plurality of magnetic fields exist inside the lens barrel. The objective is to provide a lens barrel that can reduce the above. It is another object of the present invention to provide a lens barrel that enables downsizing of the lens barrel and the imaging device and more accurate position detection.

In order to achieve the above object, the lens driving device of the present invention includes:
A moving lens group, a lens holding frame of the moving lens group, and a fixing portion that holds the lens holding frame so as to be movable in a predetermined direction;
A stepping motor with a sensor for driving the lens holding frame with respect to the fixed portion is
It consists of an actuator part, a U-shaped sheet metal, and a sensor part that detects the rotational position of the actuator,
The U-shaped sheet metal supports the output shaft of the actuator part rotatably, and fixes the stepping motor to the fixed part,
The sensor part is cylindrical or columnar, and is magnetized in the circumferential direction, and is attached to the periphery of the sensor magnet so as to rotate integrally with the output shaft of the actuator part. Having magnetic sensors arranged opposite to each other,
The sensor unit is disposed inside a sheet metal having a U-shape,
The magnetic sensor is disposed between a U-shaped sheet metal and a sensor magnet.
It is characterized by that.

  According to the present invention, in a lens driving device equipped with a sensor-equipped stepping motor using a magnetic sensor, the magnetic field sensor is more actively shielded by using a stationary metal plate of the stepping motor, thereby making the magnetic sensor more than the prior art. The disturbance magnetic field can be reduced.

  In addition, there is no restriction on the arrangement of the magnetic sensor due to other magnetic circuits as in the prior art, and it is not a configuration in which new magnetic shielding parts are added, so the degree of freedom in design does not decrease, and the lens barrel is large. Can be avoided.

  Furthermore, by improving the positional accuracy of the drive shaft and the magnetic sensor, it is possible to provide a lens drive device that can perform drive control with higher accuracy.

The perspective view of the lens drive device 100 which mounts the stepping motor 1 with a sensor based on the 1st Embodiment of this invention. (A) Perspective view of the stepping motor 1 with a sensor according to the first embodiment of the present invention (b) Front view of the stepping motor 1 with a sensor according to the first embodiment of the present invention (c) First of the present invention Side view of the stepping motor 1 with a sensor according to the embodiment (A) Cut surface of dashed-dotted line K shown in FIG. 2 (b) (b) Cut surface of dashed-dotted line L shown in FIG. 2 (b) FIG. 3B is an enlarged view of FIG. 3B for explaining the positional relationship between the pole arrangement of the sensor magnet 2 and the magnetic sensor 3. (A) Magnetic flux density in the Y-axis direction detected by the magnetic detector 3a shown in FIG. 4 (b) Magnetic flux density in the Y-axis direction detected by the magnetic detector 3b shown in FIG. 1 is a first perspective view of a lens barrel equipped with a sensor-equipped stepping motor 1 according to a first embodiment of the present invention. FIG. 2 is a second perspective view of a lens barrel on which the stepping motor with sensor 1 according to the first embodiment of the present invention is mounted. First side view of a lens barrel equipped with a stepping motor with a sensor 1 according to a first embodiment of the present invention. FIG. 7 is a first perspective view of a lens barrel equipped with a sensor-equipped stepping motor 1 according to the first embodiment of the present invention, corresponding to FIG. 6, and includes only the sensor-equipped stepping motor 1 and other lens group drive actuators. Illustration shown FIG. 9 is a second perspective view of the lens barrel on which the stepping motor with sensor 1 according to the first embodiment of the present invention corresponding to FIG. 7 is mounted, and includes only the stepping motor with sensor 1 and drive actuators of other lens groups. Illustration shown FIG. 3 is a second side view of the lens barrel on which the stepping motor with sensor 1 according to the first embodiment of the present invention is mounted, and shows only the stepping motor with sensor 1 and driving actuators of other lens groups. 1 is an exploded perspective view of a camera shake correction unit 30 according to the first embodiment of the present invention. The disassembled perspective view of the focus lens unit 40 based on the 1st Embodiment of this invention. Image diagram of disturbance magnetic field at cut surface of alternate long and short dash line M in part P shown in FIG. Image diagram of disturbance magnetic field when sheet metal 5 having a U-shape does not exist at the cut surface of dashed-dotted line M in part P shown in FIG. FIG. 11 is an image diagram of a disturbance magnetic field when the bent shape portion 17 is not present in the U-shaped sheet metal 5 at the cut surface of the alternate long and short dash line M in the P portion shown in FIG. 11 according to the second embodiment of the present invention. In P part shown in FIG. 11 according to the second embodiment of the present invention, an image of a disturbance magnetic field at the end of a sheet metal 5 having a U-shape. (A) Perspective view of stepping motor 1 with sensor according to the third embodiment of the present invention (b) Front view of stepping motor 1 with sensor according to the third embodiment of the present invention (c) Third view of the present invention Side view of the stepping motor 1 with a sensor according to the embodiment (A) Cut surface of dashed-dotted line N shown in FIG. 18 (b) (b) Cut surface of dashed-dotted line O shown in FIG. 18 (b)

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Example 1]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. In the drawing, the optical axis direction is set as the Z axis, the X axis is set in a predetermined direction perpendicular to the optical axis, and the direction perpendicular to the X axis is set as the Y axis.

  The lens barrel on which the lens driving device 100 according to the first embodiment of the present invention is mounted is composed of four lens groups. In each lens group, the first lens group is fixed, the second lens group is movable in the optical axis direction by a zooming optical system, and the third lens group is moved in an optical axis orthogonal plane by a camera shake correction optical system. The fourth lens group can be moved in the optical axis direction by a focusing optical system. Of these optical systems, the case where the lens driving device 100 of the present invention is applied to the second lens group for zooming will be described below as an example. However, the present invention is not limited to this and is applied to a focusing optical system or the like. Can also be applied.

  First, the sensor-equipped stepping motor 1 mounted in the lens driving device 100 of the present invention applied to the second lens group for zooming will be described. FIG. 1 is a perspective view of a lens driving device 100 equipped with a sensor-equipped stepping motor 1 according to a first embodiment of the present invention. 2A is a perspective view of the sensor-equipped stepping motor 1 mounted on the lens driving device 100 of FIG. 1, FIG. 2B is a front view, and FIG. 2C is a side view. 3A is a cut surface taken along the alternate long and short dash line K shown in FIG. 2B, and FIG. 3B is a cut surface taken along the alternate long and short dash line L shown in FIG.

  The sensor-equipped stepping motor 1 includes a sensor unit 4, an actuator unit 6, and a sheet metal 5 having a U-shape.

  The U-shaped sheet metal 5 is a member that rotatably supports a screw 7 that is an output shaft of the actuator section 6 and fixes the stepping motor 1 with the sensor to a fixing section (not shown). Made of material.

The sensor unit 4 is a cylindrical magnet that is multipolarly magnetized in the circumferential direction, and is arranged so as to face the periphery of the sensor magnet 2 and the sensor magnet 2 that is coaxially and integrally mounted with the screw 7. The magnetic sensor 3 is made up of. As shown in FIG. 3 (b), the magnetic sensor 3 includes the U-shaped sheet metal 5 inside the end portion separated from the actuator portion and the U-shaped sheet metal 5 and the sensor magnet 2. It is arranged between.
The actuator unit 6 includes a magnet 61 that is coaxially and integrally attached to the screw 7 that is an output shaft, and a fixed coil 62 and a yoke 63. When a current is passed through the coil 62 through the flexible substrate 8, electromagnetic force is generated and the screw 7 rotates.

  Next, the relationship between the rotation of the screw and the output of the magnetic sensor 3 will be described with reference to FIGS. FIG. 4 is an enlarged view of FIG. 3B, in which the sensor magnet 2 has N and S poles alternately magnetized on the circumference. The magnetic sensor 3 in the first embodiment is an MR element, and the orientation of the magnetic sensor 3 is determined and arranged so as to detect the magnetic field in the Y-axis direction shown in FIG. 4 among the magnetic fields generated by the sensor magnet 2. Yes. The magnetic sensor 3 has two magnetic detection units 3a and 3b. In the Y-axis direction, the distance from the center of the sensor magnet 2 to the magnetic detection unit 3a is d1, and from the center of the sensor magnet 2 The distance to the magnetic detection unit 3b is d2.

  FIG. 5A shows an output example of the magnetic detection unit 3a when the screw 7 rotates at a constant speed, and FIG. 5B shows an output example of the magnetic detection unit 3b. In each graph shown in FIGS. 5A and 5B, the horizontal axis represents time, and the vertical axis represents the strength of the magnetic field to be detected. The outputs of the magnetic detection units 3a and 3b are sin waves having the same amplitude. It is desirable that the phase difference is 90 degrees. Thereby, since the magnetic flux obtained periodically changes with the rotation of the screw 7, the rotation amount of the screw 7 can be detected by the magnetic sensor 3 from the change in the output value of the magnetic detection unit 3 a or 3 b.

  Moreover, the rotation direction of the screw 7 can also be obtained by comparing changes in the output values of the magnetic detection units 3a and 3b. The phase difference changes depending on the position of the magnetic sensor 3. Therefore, it is necessary to adjust the position of the magnetic sensor 3 in the Y-axis direction so as to correspond to the pole of the sensor magnet 2 so that d1 = d2 and the phase difference between the output waveforms of the magnetic detectors 3a and 3b is 90 degrees. is there. Therefore, while assembling the adhesive, the magnetic sensor 3 is moved together with the flexible substrate 8 in the Y-axis direction on the surface of the U-shaped sheet metal 5 while observing the output value of the magnetic sensor 3 and the position of the magnetic sensor 3 is determined. The magnetic sensor 3 including the flexible substrate 8 is fixed with an adhesive or the like.

  Next, a lens driving device 100 that moves in the optical axis direction using the above-described sensor-equipped stepping motor 1 will be described with reference to FIG.

  The second lens group 9 for zooming is held by a lens holding frame 10, and a rack 13 is attached to a sleeve portion 15 holding the guide shaft 11 so as to be rotatable around an axis parallel to the optical axis. . The rack 13 has a tooth portion that is screwed with the screw 7, and is urged around the axis parallel to the optical axis direction and the optical axis with respect to the lens holding frame 10 by the urging spring 14. Yes. Therefore, the lens holding frame 10 can move in the Z-axis direction along the guide shaft 11 via the rack 13 by the rotation of the screw 7.

  The lens holding frame 10 has a protrusion 18 for detecting an absolute value, and the lens driving device 100 includes a photo interrupter 16 on the flexible substrate 8 that detects that the protrusion has been transmitted. Thereby, the lens holding frame 10 can be moved in a predetermined direction, and the position where the projection 18 has passed through the photo interrupter 16 can be set as the reference position.

  With the configuration described above, the lens driving device 100 calculates the screw rotation amount and rotation angle from the output value of the magnetic sensor 3 of the sensor-equipped stepping motor 1, and sets the current position of the lens holding frame 10 with respect to the reference position. Can be derived. The control device (not shown) controls the current applied to the coil 62 of the sensor-equipped stepping motor 1 based on the difference between the derived current position of the lens holding frame 10 and the target position. The drive control is performed.

  Next, a relationship between the sensor unit 4 of the sensor-equipped stepping motor 1 and the disturbance magnetic field in the lens barrel having the lens driving device 100 described above will be described.

  FIG. 6 shows a lens barrel according to the first embodiment of the present invention. The lens driving device 100 holding the second lens group, the camera shake correction unit 30 holding the third lens group 312, and the fourth lens group 407 are shown. 3 is a first perspective view showing a positional relationship with a held focus unit 40. FIG. 7 is a second perspective view seen from the direction opposite to the Z axis with respect to the perspective view of FIG. 6, and FIG. 8 is a side view of the lens barrel. An exploded perspective view of the camera shake correction unit 30 is shown in FIG. 12, and an exploded perspective view of the focus unit 40 is shown in FIG.

  As shown in FIGS. 6 to 8, in the lens barrel of the first embodiment of the present invention, the image stabilizing unit 30 and the focus unit 40 are arranged on the rear side in the Z-axis direction of the lens driving device 100 described above. Yes.

  In the image stabilization unit 30, a shift base 310 is fixed to a lens barrel body (not shown). And the movable part 320 including the lens holder 306 is configured to be movable in the XY plane via the ball 309 with respect to the fixed part 330 shown in FIG. The actuator is a linear actuator, and the fixed portion 330 includes a shift base 310, a drive coil 302, a coil yoke 301, and a movable portion position detection sensor 305. On the other hand, the movable portion 320 is configured such that a ball holder 307 for supporting a ball and a lens holder 306 is integrated with a magnet holder 308 for holding a drive magnet 303 and a back yoke 304 by fastening screws 311.

  The focus unit 40 is a unit in which the lens holder 406 that holds the fourth lens group 407 can move in the Z-axis direction along the guide shafts 19 and 20. Similar to the camera shake correction unit 30, the actuator is a linear actuator, and the lens holder 406, which is a movable part, holds the drive coil 401. On the other hand, the fixed portion includes a U-shaped yoke 403 that penetrates the air-core portion of the drive coil 401, a drive magnet 402, and a flat plate yoke 404 that covers the opening of the U-shaped yoke 403.

  FIG. 9 is a first perspective view corresponding to FIG. 6 and showing only the actuators of both the camera shake correction unit 30 and the focus unit 40 and the sensor-equipped stepping motor 1 according to the first embodiment of the present invention. FIG. 10 is a second perspective view seen from the opposite direction of the Z axis with respect to the perspective view of FIG. 9, and FIG. 11 is a side view seen from the positive X axis direction.

  As shown in FIGS. 9 to 11, the lens barrel in the first embodiment includes a plurality of actuators including magnets and magnetic materials. The action of the U-shaped sheet metal 5 for reducing the disturbance magnetic field received by the magnetic sensor 3 from these actuators will be described below with reference to the magnetic field image diagrams shown in FIGS.

  14 and 15 are image diagrams of the disturbance magnetic field in the section indicated by the alternate long and short dash line M in the P portion shown in FIG. It is the actuator of the camera shake correction unit 30 disposed closest to the magnetic sensor 3 that has the strongest influence as the disturbance magnetic field received by the magnetic sensor 3, and the two drive magnets 303. Each of the two drive magnets 303 is magnetized in the opposite direction in the Z-axis direction, and has a pole arrangement as shown in FIGS.

  First, the magnetic sensor 3 that is not affected by the disturbance magnetic field from the drive magnet 303 without using the U-shaped sheet metal 5 will be described with reference to FIG. The magnetic field exits the north pole of the drive magnet 303 and enters the south pole. The strength of the magnetic field is proportional to the distance from the drive magnet 303, but the magnetic sensor 3 is directly affected by the magnetic field from the drive magnet 303.

  Next, the case where there exists the sheet metal 5 which has the U-shaped shape which concerns on the 1st Example of this invention using FIG. 14 is demonstrated. Even when the U-shaped sheet metal 5 is present, the magnetic field exits from the N pole of the drive magnet 303 and enters the S pole as described above. However, the magnetic field passes through the U-shaped sheet metal 5 having a higher magnetic permeability than air in the middle of exiting from the N pole and entering the S pole.

  First, the magnetic field that has entered the U-shaped sheet metal 5 with the bent portion shape 17 close to the drive magnet 303 changes the magnetic field flow in the X-axis direction before reaching the magnetic sensor 3. And the magnetic field which entered in the part which does not have the bending part shape 17 changes the flow to the Z-axis direction which is the longitudinal direction of the U-shaped sheet metal 5, and the magnetic field around the magnetic sensor 3 decreases, The influence of the disturbance magnetic field on the magnetic sensor 3 is reduced.

  The U-shaped sheet metal 5 is effective in reducing the disturbance magnetic field with respect to the magnetic sensor 3 even when the bent shape portion 17 is not provided. This example will be described later as a second embodiment.

  The magnetic sensor 3 is arranged inside the end portion of the U-shaped sheet metal 5 because the disturbance magnetic field is actively passed through the bending portion forming the U-shape and the direction of the disturbance magnetic field transmitted through the magnetic sensor 3 is determined. This is for changing the magnetic field in the sensitivity direction.

  Further, by arranging the sensor unit 4 inside the end portion of the U-shaped sheet metal 5, the bearing portion of the screw 7 in the sensor unit 4 and the U-shaped sheet metal 5 can be disposed close to each other. As a result, the coaxiality between the screw 7 serving as the drive shaft and the sensor magnet 2 and the positional accuracy of the sensor magnet 2 with respect to the U-shaped sheet metal 5 can be increased, so that the detection accuracy of the magnetic sensor 3 is improved. Controllability of the sensor-equipped stepping motor 1 is also improved.

  As described above, the sensor unit 4 composed of the magnetic sensor 3 and the sensor magnet 2 according to the first embodiment is arranged inside the end portion of the U-shaped sheet metal 5 apart from the actuator unit 6. doing.

  Further, the sensor unit 4 may be arranged at the end of the same U-shaped sheet metal 5 as the actuator unit 6, but there is a possibility that a magnetic field that causes disturbance of the magnetic sensor 3 may be generated from the actuator unit 6. Considering the above, it is preferable to separate them.

  In addition, in the operation of assembling the sensor magnet 2, the screw 7, and the actuator unit 6 to the U-shaped sheet metal 5, the actuator unit 6 and the sensor unit 4 are separated from both ends of the U-shaped sheet metal 5. The workability is improved by arranging them. First, a hole through which the sensor magnet 2 can pass is made in one end portion of the U-shaped sheet metal 5, and the sensor magnet 2 is attached to the screw 7 protruding from the actuator portion 6 in advance. Next, the actuator 6 is gripped, and the screw 7 with the sensor magnet 2 attached to the tip is passed through the hole formed in the U-shaped sheet metal 5, and the tip of the screw 7 is the end of the U-shaped sheet metal 5. Attach to the bearing part. By such a procedure, the assembly of the sensor-equipped stepping motor 1 becomes possible.

[Example 2]
A second embodiment to which the present invention is applied will be described below with reference to FIGS. The second embodiment is a modified type of the U-shaped sheet metal 5 in the first embodiment, and is the same as the first embodiment except for the U-shaped sheet metal 5. The explanation of the common part is omitted.

  The sheet metal 5 having a U shape in the second embodiment does not have the bent shape portion 17. FIG. 16 is an image diagram of a disturbance magnetic field on the cut surface of the alternate long and short dash line M in the P portion shown in FIG. 11 corresponding to the second embodiment. Although the U-shaped sheet metal 5 does not have the bent portion 17, the flow of the magnetic field is greatly different from that in FIG. 15 where there is no U-shaped sheet metal 5. Most of the magnetic field emitted from the north pole of the drive magnet 303 flows in the Z-axis direction when it enters the U-shaped sheet metal 5.

  FIG. 17 shows a three-dimensional image of the magnetic field flow. The magnetic field emitted from the N-pole of the drive magnet 303 enters the U-shaped sheet metal at P1, passes through the bent portion forming the U-shaped sheet metal 5 and exits from P2, and becomes the S-pole. Return. In this way, by changing the flow of the magnetic field into the U-shaped sheet metal 5, the direction of the magnetic field transmitted through the magnetic sensor 3 is changed to the Z direction, and the magnetic field in the Y direction, which is the sensitivity direction of the magnetic sensor 3. Is reduced. As a result, the magnetic sensor 3 is not directly affected by the disturbance magnetic field.

[Example 3]
Hereinafter, a third embodiment to which the present invention is applied will be described with reference to FIGS. The third embodiment is also a modification of the U-shaped sheet metal 5 in the first embodiment, and is the same as the first embodiment except for the U-shaped sheet metal 5. Therefore, the description of the common part with the first embodiment is omitted.

  18A is a perspective view of the sensor-equipped stepping motor 1 mounted on the lens driving device 100 of FIG. 1, FIG. 18B is a front view, and FIG. 18C is a side view. FIG. 19A is a cut surface taken along the alternate long and short dash line N shown in FIG. 18B, and FIG. 19B is a cut surface taken along the alternate long and short dash line O shown in FIG.

  As shown in FIGS. 18 and 19, the U-shaped sheet metal 5 in the third embodiment has a concave shape 21 extending in the Y-axis direction at a location where the magnetic sensor is disposed.

  As described above, in order to detect the rotation amount and rotation angle of the screw 7 with the magnetic sensor 3 and the sensor magnet 2, the phase difference changes depending on the position of the magnetic sensor 3 in the Y-axis direction. On the other hand, it is necessary to adjust the position of the magnetic sensor 3 in the Y-axis direction.

  Therefore, the concave shape 21 extending in the Y-axis direction serves as a position guide for the magnetic sensor 3 to facilitate the position adjustment of the magnetic sensor 3 in the Y-axis direction. The magnetic sensor 3 can move along the concave shape 21 within a range d shown in FIG. Then, after the position adjustment, when the magnetic sensor 3 is fixed to the U-shaped sheet metal 5 using an adhesive, the concave shape becomes an adhesive pool, improving the adhesive strength, flowing the adhesive into other parts, etc. To prevent.

  The flow of the disturbance magnetic field is the same as in Example 1 even when the U-shaped sheet metal 5 has the concave shape 21, and the disturbance magnetic field passes through the U-shaped sheet metal 5 and enters the air from the bent portion at the end. Go out to.

  When there are a plurality of actuators in the lens barrel, the flow of the disturbance magnetic field reaching the magnetic sensor 3 changes depending on the location of the magnetic field that causes the disturbance and the direction of the magnetic field. Often different. However, by applying the present invention, the disturbance magnetic field actively passes through the U-shaped sheet metal 5, passes through the back of the magnetic sensor 3, passes through the bent portion at the end, and flows from the U-shaped sheet metal 5 to the air. It becomes a flow to come out. Thus, the U-shaped sheet metal 5 serves as a shielding plate, and reduces the magnetic field around the magnetic sensor 3.

  This embodiment uses a sheet metal for fixing the actuator output shaft, instead of adding another new part to shield the magnetic field from being disturbed by the magnetic sensor. Can be prevented. In addition, the invention is not related to the arrangement of the sensor-equipped stepping motor itself, but to the arrangement of the sensor section inside the sensor-equipped stepping motor and the sheet metal shape that receives the output shaft. Can contribute.

  In the embodiment of the present invention, the MR element is used for the magnetic sensor. However, the magnetic sensor can be applied to any magnetic sensor as long as it outputs an output signal corresponding to the strength of the magnetic force.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

1 stepping motor with sensor, 2 sensor magnet, 3 magnetic sensor,
3a, 3b Magnetic detection part, 4 sensor part, 5 U-shaped sheet metal,
6 Actuator, 61 Magnet, 62 Coil, 63 Yoke,
7 screw (output shaft), 8 flexible substrate, 9 second lens group,
10 lens holding frame, 11 first guide shaft (fixed portion), 12 second guide shaft (fixed portion),
13 racks, 14 biasing springs, 15 sleeves, 16 photo interrupters,
17 bent shape part, 18 protrusion part, 19 guide shaft, 20 guide shaft, 21 concave shape,
30 camera shake correction unit, 40 focus unit, 100 lens driving device, 301 coil yoke, 302 driving coil, 303 driving magnet,
304 Back yoke, 305 Position detection sensor, 306 Lens holder,
307 ball sheet metal, 308 magnet holder, 309 balls,
310 shift base, 311 screw, 312 third lens group, 320 movable part,
330 fixed portion, 401 drive coil, 402 drive magnet, 403 U-shaped yoke,
405 Flat yoke, 406 Lens holder, 407 Fourth lens group

Claims (4)

A moving lens group;
A lens holding frame of the moving lens group;
A fixing portion for holding the lens holding frame so as to be movable in a predetermined direction;
A stepping motor with a sensor for driving the lens holding frame with respect to the fixed portion is
It consists of an actuator part, a U-shaped sheet metal, and a sensor part that detects the rotational position of the actuator,
The U-shaped sheet metal supports the output shaft of the actuator part rotatably, and fixes the stepping motor to the fixed part,
The sensor unit is cylindrical or columnar, is multipolarly magnetized in the circumferential direction, and is attached so as to be rotatable integrally with the output shaft of the actuator unit;
It has a magnetic sensor arranged facing the periphery of the sensor magnet,
The sensor unit is disposed inside a sheet metal having a U-shape,
The magnetic sensor is disposed between a U-shaped sheet metal and a sensor magnet. One of the sensor unit and the actuator unit is disposed on one end side of a sheet metal having a U-shape, and the other is disposed on the other end side on the opposite side of the sheet metal having a U-shape. The lens driving device according to claim 1. The lens driving device according to claim 1, wherein the magnetic sensor is disposed in a concave portion of the U-shaped sheet metal. The lens driving device according to any one of claims 1 to 3, wherein the U-shaped sheet metal has a bent shape on a side surface to cover the sensor magnet.