JP2009216934A - Actuator, imaging element, and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an actuator that responds to the miniaturization and thinning of a camera and has improved driving stability. <P>SOLUTION: The actuator 1 includes a plurality of spheres 17 arranged between a holder 15 and a base 18, an energizing member 20 for energizing the holder 15 in the substantially perpendicular direction to the optical axis via at least one sphere 17, and a pressurization adjusting member 29 for adjusting the pressurization acting on the holder 15 from the energizing member 20 via the sphere 17. The pressurization adjusting member 29 adjusts the pressurization acting on the holder 15 from the energizing member 20 by deflecting the energizing member 20 in the substantially perpendicular direction to the optical axis. Thus, the pressurization acting on the holder 15 from the energizing member 20 is adjusted to a suitable range, so that the holder 15 can stably move in the optical axis direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an actuator, an imaging device, and an electronic apparatus that include a sphere that supports a holder so as to be movable along an optical axis direction.

  In recent years, cameras built in portable electronic devices are becoming smaller, thinner, and higher in image quality. Many cameras tend to be equipped with an autofocus function for improving image quality.

  In general, a voice coil system is widely used as an autofocus function. In the voice coil system, auto-focusing is performed by moving a holder holding an optical system by driving a coil or a magnet by an electromagnetic induction phenomenon inside an actuator. In such an autofocus, it is necessary to support the holder so as to be movable in the actuator.

  Patent Document 1 discloses an actuator that supports a holder using a pair of leaf springs. In the actuator described in Patent Document 1, the pair of parallel leaf springs are attached above and below the holder in the optical axis direction, and deforms within the actuator according to the movement of the holder during autofocus. The displacement of the holder is supported by the deformation of the leaf spring.

  However, in order to reduce the size and thickness of the actuator described in Patent Document 1 in accordance with the recent downsizing and thinning of cameras, it is necessary to thin the leaf spring that supports the holder. The strength of the will decrease. For this reason, problems such as a decrease in the posture stability of the holder and a decrease in the shock resistance performance of the actuator occur.

Patent Document 2 discloses a lens barrel (actuator) that supports a movable barrel (holder) using a biasing member. In the actuator described in Patent Document 2, a hard ball is arranged between the holder and the fixed lens barrel (support), and a biasing member biases the holder in a direction perpendicular to the optical axis via the hard ball. . Therefore, the holder is held by being pressed against the hard ball, and can move smoothly in the optical axis direction via the hard ball.
JP 2006-50693 A (published February 16, 2006) JP-A-8-29656 (published February 2, 1996)

  However, like the actuator described in Patent Document 2, the driving characteristics of an actuator that supports a holder using a biasing member are greatly affected by the pressure applied to the holder from the biasing member. For this reason, for example, when the pressurization applied to the holder from the urging member deviates from the optimum value due to a molding failure caused by a mold, there is a possibility that the drive stability of the actuator is lowered.

  For example, when the pressure applied to the holder from the urging member is larger than the thrust of the actuator, the operation of the actuator is hindered. On the other hand, when the pressure applied to the holder from the urging member is clearly too small than the thrust of the actuator, the force acting on the holder deviates from the center of the holder. Thereby, the posture stability of the holder is lowered, and the driving stability of the actuator is lowered.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an actuator that can be reduced in size and thickness and has improved driving stability.

  In order to solve the above problem, an actuator according to the present invention includes a holder that holds an optical member, a support that holds the holder so as to be movable in the optical axis direction, and a gap between the holder and the support. A plurality of spheres arranged and supporting the holder, and a biasing member that biases the holder in a direction substantially perpendicular to the optical axis via at least one sphere of the plurality of spheres, A pressure adjusting member that adjusts the pressure acting on the holder from the urging member is provided.

  According to the above configuration, the actuator according to the present invention moves the holder holding the optical member in the optical axis direction in order to move the optical member. The holder is movably held by the support and is supported by a plurality of spheres.

  The plurality of spheres are arranged between the holder and the support, and the urging member urges the holder in a direction perpendicular to the optical axis via at least one sphere of the plurality of spheres. ing. Therefore, the sphere and the holder, and the sphere and the support are pressed against each other, and when the holder moves to move in the optical axis direction, the sphere rotates due to friction with the side surface of the holder. By this rotation, the sphere has a frictional force with the holder and the support, and the movement of the holder in the optical axis direction is supported by the sphere.

  The movement of the holder in the optical axis direction is affected by the pressure applied to the holder from the biasing member. If the pressure applied to the holder from the urging member is out of the proper range, the drive of the actuator becomes unstable. In the actuator according to the present invention, the pressurizing member is adjusted so that the pressurizing force applied from the urging member to the holder falls within an appropriate range. Therefore, the pressure applied to the holder is stable, and the driving stability of the actuator can be improved.

  In the actuator according to the present invention, it is preferable that the urging member is an elastic member. According to the above configuration, the biasing member can be bent by configuring the biasing member using a polymer material, a leaf spring, or the like, so that the pressure adjustment can be easily performed.

  Furthermore, the actuator which concerns on this invention WHEREIN: It is preferable that the said urging | biasing member is integrally formed with the said support body, and has a space between the said support bodies.

  According to the above configuration, since the urging member is configured as a part of the support, it can be manufactured at low cost and easily, and downsizing is easy. Furthermore, since there is a space between the urging member and the support, it is possible to secure a space for arranging the pressure adjusting member or a space for deflecting the urging member for adjusting the pressure. it can.

  Moreover, the actuator which concerns on this invention WHEREIN: It is preferable that the said pressurization adjustment member bends the said biasing member to the said holder side or the said support body side in the direction substantially perpendicular | vertical with respect to the said optical axis.

  According to the above configuration, if the pressure applied to the holder from the urging member is too large, the pressure adjusting member bends the urging member toward the support in the direction substantially perpendicular to the optical axis. The pressure applied to the holder from the biasing member can be reduced and adjusted to an appropriate pressure.

  On the other hand, when the pressure applied to the holder from the biasing member is too small, the pressure adjusting member is bent from the biasing member by bending the biasing member toward the holder in a direction substantially perpendicular to the optical axis. The pressurizing pressure acting on the holder can be increased and adjusted to an appropriate pressurizing pressure.

  Therefore, the pressurization adjusting member can be adjusted to an appropriate pressurization by adjusting either the depressurization or the pressurization with respect to the pressurization applied to the holder from the urging member.

  Moreover, the actuator which concerns on this invention WHEREIN: It is preferable that the said pressurization adjustment member is an adhesive agent or a pin installed between the said support body and the said urging | biasing member. Or the actuator which concerns on this invention WHEREIN: It is preferable that the said pressurization adjustment member is a magnet or a coil through which an electric current flows, and is each installed in the said support body and the said urging | biasing member.

  According to the above configuration, the pressure adjusting member is preferably in the direction on the holder side or the base side in a direction substantially perpendicular to the optical axis with respect to the biasing member by selecting the type, amount, or arrangement thereof. Or a preferred amount of force can be applied. Therefore, the pressurizing member can bend the biasing member to a preferred position.

  The actuator according to the present invention includes an optical member held by the holder, and an imaging element that converts an image formed on the imaging surface by the optical member into an electrical signal, such as a camera module. Functions as an imaging device.

  In addition, the imaging device can be applied to all devices on which a camera is mounted, such as an electronic device or an automobile.

  According to the actuator of the present invention, since the pressure adjusting member that adjusts the pressure applied to the holder from the biasing member via the sphere is provided, the posture of the holder is kept stable, and as a result, the driving stability of the actuator Can be improved.

  The actuator 1 which concerns on 1st embodiment of this invention is demonstrated based on FIGS. 1-12. In the following description, various limitations preferable for carrying out the present invention are given, but the scope of the present invention is not limited to the following embodiments and drawings.

(Configuration of actuator 1)
The principal part structure of the actuator 1 in this embodiment is demonstrated below with reference to FIGS. FIG. 2 is an exploded perspective view showing a main configuration of the actuator 1. FIG. 3 is a perspective view showing the configuration of the main part of the actuator 1. FIG. 4 is a cross-sectional view showing the main configuration of the actuator 1.

  As shown in FIGS. 2 to 4, the actuator 1 includes an upper guide (support) 9, a leaf spring 11, a magnet 12, a yoke 13, a coil 14, a holder 15 that holds an optical member 16, a sphere 17, and a base (support). Body) 18 and a regulating member 21. Although not shown here, the actuator 1 further includes an urging member 20 and a pressure adjusting member 29.

  Although the image sensor 19 is not a constituent element of the actuator 1, the actuator 1 includes the image sensor 19, and is used for autofocusing of an imaging device mounted on an electronic device such as a mobile phone. That is, the actuator 1 forms an image of an object to be imaged on the image sensor 19 by the optical member 16. Therefore, in the present embodiment, the direction in which the optical member 16 forms an image is the “optical axis direction”, the object side to be imaged in this optical axis direction is the “object side”, and the opposite side to the object side is the “image”. It is defined as “face side”.

  The actuator 1 has a magnetic circuit for driving the holder 15 that holds the optical member 16 in order to perform autofocus. This magnetic circuit includes a magnet 12, a yoke 13, and a coil 14. The yoke 13 has a cylindrical shape, and a cylindrical magnet 12 is fixed to the inner wall with an adhesive. On the other hand, the coil 14 accommodates the holder 15 inside and is fixed integrally. The coil 14 and the holder 15 are disposed so as to be accommodated in the cylindrical shape of the yoke 13 and the magnet 12.

  According to the above configuration, when an electric current is applied to the coil 14, an electromagnetic induction phenomenon occurs between the magnet 12 and the coil 14, and the optical axis direction with respect to the holder 15 that is integrally fixed to the coil 14. The thrust is generated. By this thrust, the holder 15 moves in the optical axis direction. The thrust generated in the holder 15 is proportional to the amount of current applied to the coil 14.

  The holder 15 is held movably on the object side by the upper guide 9 and is movably held on the image plane side by the base 18. A plate spring 11 is disposed on the object-side surface of the holder 15 so as to apply a pressure proportional to the amount of movement of the holder 15 in the optical axis direction.

  In addition, on the object side of the upper guide 9 and the image plane side of the base 18, regulating members 21 are respectively installed. For this reason, even if the holder 15 moves in the optical axis direction on either the object side or the image plane side, the holder 15 abuts on the respective regulating members 21, so that the movement of the holder 15 in the optical axis direction is limited.

(About sphere 17)
In the actuator 1, the movement of the holder 15 is supported by a sphere 17. The sphere 17 will be described below with reference to FIG.

  First, as shown in FIG. 4, the spheres 17 are preferably arranged on the object side and the image plane side of the holder 15. As a configuration for that purpose, a recess 15 a is formed on the side surface of the holder 15 at a position facing the upper guide 9 or the base 18. Further, insertion holes 9 a and 18 a are formed at positions facing the recess 15 a in the upper guide 9 and the base 18, respectively. Therefore, a gap is formed by the recessed portion 15a and the insertion hole 9a or 18a on the object side and the image plane side of the holder 15, respectively.

  The spherical body 17 is disposed in the gap and is urged by an urging member to be described later, thereby reliably contacting the side surface of the holder 15 and the upper guide 9 or the base 18. Therefore, the movement of the holder 15 in the optical axis direction is supported by the sphere 17 that rotates by friction with the holder 15. On the other hand, the movement of the holder 15 in a direction substantially perpendicular to the optical axis is restricted by the sphere 17.

  Further, it is sufficient that at least three spheres 17 are arranged on each of the object side and the image plane side on the side surface of the holder 15. The arrangement of two is not preferable because the position of the holder 15 becomes unstable when the holder 15 moves in the optical axis direction.

  In addition, it is preferable that the spheres 17 be arranged such that the angles between the straight lines connecting the centers of the holders 15 and the spheres 17 are equal to each other in a plane substantially perpendicular to the optical axis. For example, when three spheres 17 are arranged on the object side or image plane side, the center of the holder 15 and each sphere 17 are connected and adjacent to each other in a plane substantially perpendicular to the optical axis as shown in FIG. The angles between the straight lines are all about 120 °. FIG. 5 is a schematic view of the actuator 1 viewed from the optical axis direction.

  With the above configuration, since the sphere 17 is arranged so as to sandwich the holder in a direction substantially perpendicular to the optical axis, the support of the holder 15 by the sphere 17 is not biased. Therefore, the movement of the holder 15 in the optical axis direction can be supported more accurately. The same applies to the case where three or more spheres 17 are arranged except that the angle changes.

  Further, the spherical body 17 in the actuator 1 is preferably made of a material that does not affect the arrangement in a strong magnetic field and does not affect the magnetic flux distribution by the magnetic circuit, that is, a nonmagnetic material. Examples include ceramic, brass, glass, and nonmagnetic stainless steel.

(Regarding the biasing member 20)
In the actuator 1, the urging member 20 urges the holder 15 via the sphere 17 in a direction substantially perpendicular to the optical axis. The urging member 20 will be described below with reference to FIGS.

  As shown in FIG. 4, the urging members 20 are preferably disposed on the upper guide 9 and the base 18, respectively, and one sphere 17 is preferably disposed. With the above configuration, the urging member 20 can urge the holder 15 via the sphere 17 in a direction substantially perpendicular to the optical axis without deviation.

  As shown in FIG. 5, it is preferable that the biasing member 20 disposed on the base 18 is formed integrally with the base 18 and the biasing member 20 disposed on the upper guide 9 is formed integrally with the upper guide 9. Furthermore, a space 28 is preferably provided between the urging member 20 and the base 18 and between the urging member 20 and the upper guide 9. As will be described in detail later, a pressure adjusting member 29 is disposed in the space 28. The space 28 also serves as a space for the biasing member 20 to bend toward the base 18 in a direction substantially perpendicular to the optical axis direction.

  The urging member 20 is preferably an elastic member such as a polymer material or a leaf spring.

(Comparative example of actuator 1)
Here, as a comparative example of the actuator 1 of the present invention, the pressurization acting on the holder 15 using an actuator not provided with the pressurization adjusting member 29 will be described below with reference to FIGS. FIGS. 6, 7 </ b> A, and 8 </ b> A are schematic views of the holder 15 viewed from the optical axis direction, and FIGS. 7B and 8B are diagrams illustrating the addition to the center of gravity G of the holder 15. It is a figure which shows the triangle of the force formed using the pressure. In addition, in the actuator of a comparative example, the same member number is attached | subjected to the same member as the actuator 1. FIG.

  In the actuator of the comparative example, three spheres 17 are arranged, and a force acting on the holder 15 as shown in FIG. 6 is generated. f1 indicates a force applied to the holder 15 from the biasing member 20 via the sphere 17, and f2 and f3 indicate reaction forces acting on the holder 15 from the support 18 via the sphere 17. G indicates the center of gravity of the holder 15.

  In the actuator of the comparative example, when the pressure applied from the urging member 20 to the holder 15 is larger than the thrust of the actuator, the actuator may not be able to operate. Assuming that the spring constant of the urging member 20 is 1 gf / μm and the rolling friction coefficient with the holder 15 of the sphere 17 is 0.01, the urging member 20 is bent inward by 10 μm from the optimum position. . At this time, the pressure f1 applied to the holder 15 from the urging member 20 via the spherical body 17 is applied by 10 gf more than the optimum value. If f2 and f3 are also simply increased by the same amount, the frictional force applied from the sphere 17 to the holder 15 is increased by 10 gf × 3 × 0.01 = 0.3 gf. For this reason, if a step current having a thrust of 0.25 gf for each step is applied to the actuator of the comparative example, this actuator cannot be operated. Therefore, in order to realize stable driving of the actuator, it is necessary that the magnitude of the pressure applied from each sphere 17 to the holder 15 is within a necessary range.

  Further, in the actuator of the comparative example, when the pressure applied to the holder from the urging member is clearly too small than the thrust of the actuator, the force acting on the holder may deviate from the center of the holder. Specifically, as shown in FIG. 7, the force acting on the holder 15 from the sphere 17 has a different value and does not go to the center of the holder 15. This situation can occur particularly when a burr formed as an extra protrusion when the actuator member is formed affects the sliding surface with the sphere 17.

  Under the situation of FIG. 7, during the operation of the actuator, the force f constantly acts on the holder 15 while changing the magnitude and direction, affecting the operating characteristics of the actuator. Therefore, the posture stability of the holder 15 is lowered. Therefore, as shown in FIG. 8B, it is preferable that the pressure applied to the center of gravity G of the holder 15 is adjusted so as to form an equilateral triangle having no moment around the optical axis.

(Pressure range)
In contrast to the above-described comparative example, the actuator 1 according to the present invention is provided with a pressure adjusting member 29. Therefore, the pressure applied to the holder 15 from the urging member 20 via the sphere 17 is adjusted by the pressure adjusting member 29. Therefore, the range of the pressurization for the holder 15 to operate when the thrust is most required for driving the actuator 1 will be described below with reference to FIG. FIG. 9 is a schematic diagram showing an external force acting on the holder 15. The case where the thrust is most required for driving the actuator 1 is a case where the actuator 1 is driven in a direction opposite to the gravity of the holder 15, and the thrust acting on the holder 15 is rolling friction, gravity of the holder 15, And the case of working in the opposite direction to air resistance.

  As shown in FIG. 9, the pressure applied to the holder 15 from each sphere 17 is f1, f2, and f3, the mass of the holder 15 is M, the gravitational acceleration is g, the rolling friction coefficient of the sphere 17 is μr, The rolling friction forces acting on the holder 15 are μr × f1, μr × f2, and μr × f3, the thrust of the actuator 1 by electromagnetic force is F, the air resistance is fa, and the acceleration of the holder 15 is a. In FIG. 9, illustration of f3 and μr × f3 is omitted.

  In FIG. 9, when the direction in which the thrust of the actuator 1 is acting is a positive direction, the equation of motion of the holder 15 is expressed by the following equation (1).

M × a = F−μr × (f1 + f2 + f3) −M × g−fa (1)
In the formula (1), in order for the actuator 1 to drive, a> 0, so the thrust F of the actuator 1 is a value represented by the following formula (2).

F> μr × (f1 + f2 + f3) + M × g + fa (2)
Therefore, the range of pressurization is shown in the following formula (3).

(F1 + f2 + f3) <(F−M × g−fa) / μr (3)
For example, in formula (3), when the thrust F is 0.25 gf, the mass of the holder 15 is 0.1 g, the rolling friction coefficient μr is 0.01, and the air resistance fa is ignored, the range of pressurization Is shown in the following equation (4).
(F1 + f2 + f3) <15 gf (4)
At this time, the pressure applied from each sphere to the holder 15 is about 4 gf at the maximum. However, in actuality, when the actuator 1 is driven, the friction coefficient between the sphere 17 and the sliding surface contributes not only rolling friction but also sliding friction. In general, sliding friction is much larger than rolling friction. Therefore, in order for the actuator 1 to realize a stable drive while ensuring a sufficient thrust, the range of the pressurization expressed by the equation (4) is further limited. Further, in order to drive the actuator 1 while securing a sufficient thrust, it is preferable that the slip ratio indicating the sliding friction ratio is as small as possible. The range of pressurization in consideration of sliding friction will be described in detail below.

  When the actuator 1 is driven in the direction of gravity and movement of the holder 15, that is, when the sphere 17 is most slidable, the pressure range for the holder 15 to operate will be described below with reference to FIG. 10. FIG. 10 is a schematic diagram showing an external force acting on the holder 15. The sliding friction coefficient at this time is μs.

  In FIG. 10, first, in order to keep the slip ratio small, it is necessary to satisfy the following equation (5). In order to satisfy Expression (5), in addition to largely adjusting the pressure applied to the holder 15 from the sphere 17, the sliding friction coefficient μs between the sphere 17 and the holder 15 is selected by selecting the sphere 17 or a member of the holder 15. May be increased.

(F1 + f2 + f3)> (F + M × g−fa) / μs (5)
When the expression (5) is satisfied and the expression (3) which is a condition of an appropriate pressure range for driving the actuator is satisfied, the pressure range is expressed by the following expression (6).
(F + M × g−fa) / μs <(f1 + f2 + f3) <(F−M × g−fa) / μr
... (6)
The actuator 1 can be driven while avoiding the slip of the sphere by adjusting the pressurization applied to the holder from the sphere 17 so as to satisfy the range of the pressurization shown in the equation (6).

(Selection of pressure adjusting member)
In the actuator 1 according to the present invention, the pressure adjusting member 29 only needs to be able to adjust the biasing member 20 to the holder 15 side or the base 18 side in a direction substantially perpendicular to the optical axis. Here, a configuration example of the pressure adjusting member 29 will be described below with reference to FIGS. 1, 11, and 12. 1, FIG. 11 and FIG. 12 are schematic views showing the pressurizing adjustment member 29. In the following description, the biasing member 20 provided on the base 18 will be described, but the same applies to the biasing member 20 provided on the upper guide 9.

  First, the case where an adhesive is used as the pressure adjusting member 29 will be described with reference to FIG. As the adhesive, an adhesive that cures and shrinks after application is used. As for the method of installing the pressure adjusting member 29, as shown in FIG. 1, an adhesive is applied to the urging member 20 and the base 18 so as to fill a part of the space 28. At the time of application, the type of adhesive and the application amount are adjusted, and the applied adhesive is cured and contracted so that the biasing member 20 is adjusted. In FIG. 1, before the pressurizing adjustment member 29 is installed, the biasing member 20 that is bent toward the holder 15 in the direction substantially perpendicular to the optical axis from the optimal position is shown by the arrow in FIG. It is bent in the direction. Thereby, the pressurization adjusting member 29 can reduce the pressurization acting on the holder 15.

  Moreover, it is preferable that the pressurization adjusting member 29 adjusts the pressurization so that the sliding surface of the urging member 20 with the sphere 17 is parallel to the pre-pressurization adjustment even after the pressurization adjustment. Thereby, the actuator 1 can be driven stably.

  In addition, the pressurization adjustment member 29 can also increase the pressurization which acts on the holder 15 by adjusting the quantity of an adhesive agent many.

  Next, the case where a pin is used as the pressure adjusting member 30 will be described with reference to FIG. In FIG. 11, the pressurizing member 30 uses a pin having a force that attracts both ends. Further, as shown in FIG. 11, the pressure adjusting member 30 is disposed in the space 28, and both ends of the pin are connected to the biasing member 20 and the base 18. In FIG. 11, before the pressure adjusting member 30 is installed, the biasing member 20 that is bent toward the holder 15 in the direction substantially perpendicular to the optical axis from the optimum position is It is bent in the direction. The pressurizing force acting on the holder 15 can be reduced.

  On the other hand, the urging member 20 can be bent in the direction opposite to that shown in FIG. 11 by using a pin having elasticity as the pressure adjusting member 30. In this case, the pressure applied to the holder increases.

  Furthermore, the case where a magnet is used as the pressurizing member 31 will be described with reference to FIG. As shown in FIG. 12, the magnets used as the pressurization adjusting member 31 are provided on the biasing member 20 and the base 18, respectively. At this time, the magnets provided on each of the urging member 20 and the base 18 are arranged such that attractive forces on the sides facing each other work. In FIG. 12, before the pressurizing adjustment member 31 is installed, the biasing member 20 that is bent toward the holder 15 in a direction substantially perpendicular to the optical axis direction from the optimum position is indicated by an arrow by the magnetic force acting between the magnets. It is bent in the direction. Thereby, the pressurization adjusting member 31 can reduce the pressurization acting on the holder 15.

  On the other hand, when the magnets provided on the biasing member 20 and the base 18 are arranged so that the repulsive force acts on the sides facing each other, the force acts so that the biasing member 20 bends toward the holder 15 side. . In this case, the pressure applied to the holder 15 from the sphere 17 increases.

  Further, instead of using a magnet as the pressure adjusting member 31, a coil may be used. For example, one of the magnets provided on the urging member 20 and the base 18 may be replaced with a coil, or both may be replaced with a coil. When a coil is used as the pressurizing adjustment member 31, Lorentz force generated by passing a current through the coil is used.

  In the above description, the adjustment by the pressurization adjusting members 29 to 31 when the urging member 20 is deviated from the optimum position has been described. However, in the manufacturing stage of the actuator 1, the processing accuracy of the urging member 20 is not achieved. Alternatively, the urging member 20 may be designed to intentionally urge the holder 15 strongly, and the pressurization may be adjusted from that state.

(Use for imaging devices and electronic devices)
The actuator 1 can also be mounted on a camera module or other electronic devices. For example, an image pickup apparatus in which a sensor having an image pickup element is fixed to the holder 15 of the actuator 1 can be used.

  Furthermore, the imaging apparatus equipped with the actuator 1 can be used by being mounted on an electronic device such as a mobile phone, a digital still camera, or a video camera.

  In this example, the performance of the actuator 1 in this embodiment and the actuator of the comparative example were compared.

  The configuration of the actuator of the comparative example was the same as that of the actuator 1 except that the pressurizing adjustment member was not provided. Further, as the actuator of the comparative example, the urging member 20 is bent toward the holder 15 from the optimum position.

  As in the comparative example described above, the actuator 1 is applied to the holder 15 using a thermosetting adhesive as a pressure adjusting member for the biasing member 20 bent toward the holder 15 from the optimum position. What adjusted the pressure was used. The pressurization was adjusted by applying an adhesive so as to fill a part of the space 28 and then heating the adhesive at 80 ° C. for 30 minutes to cure and shrink the adhesive.

  The comparison was performed by passing a current through each of the actuator 1 and the actuator of the comparative example and measuring the amount of displacement of the holder with respect to the current value. The current value was increased in steps of 5 mA every 0.2 s up to a maximum of 80 mA, and then decreased in steps of 5 mA every 0.2 s.

  About the said comparison, the measurement result in current value 40mA-75mA was shown in FIG. 13 and FIG. FIG. 13 is a diagram showing the current value-displacement amount in the actuator of the comparative example, and FIG. 14 is a diagram showing the current value-displacement amount in the actuator 1. In FIGS. 13 and 14, the horizontal axis indicates the current value (mA), and the vertical axis indicates the displacement amount (mm).

  As shown in FIGS. 13 and 14, the displacement amount of the actuator 1 with respect to the step current was more stable than that of the actuator of the comparative example, and the displacement with respect to the input current was excellent in linearity. Therefore, it was confirmed that the drivability of the actuator 1 is improved by including the pressurizing member.

  The actuator according to the present invention can be widely used as an actuator used for autofocus of a camera module.

It is a schematic diagram which shows the pressurization adjustment member which concerns on embodiment of this invention. It is a disassembled perspective view which shows the principal part structure of the actuator which concerns on embodiment of this invention. It is a perspective view which shows the principal part structure of the actuator which concerns on embodiment of this invention. It is sectional drawing which shows the principal part structure of the actuator which concerns on embodiment of this invention. It is a figure which shows an example of arrangement | positioning of the sphere which concerns on this invention. It is a schematic diagram which shows the pressurization which acts on a holder. It is a schematic diagram which shows the pressurization which acts on a holder. It is a schematic diagram which shows the pressurization which acts on a holder. It is a schematic diagram which shows the external force which acts on a holder. It is a schematic diagram which shows the external force which acts on a holder. It is a schematic diagram which shows the pressurization adjustment member which concerns on other embodiment of this invention. It is a schematic diagram which shows the pressurization adjustment member which concerns on other embodiment of this invention. It is a figure which shows the electric current-displacement characteristic in the actuator of a comparative example. It is a figure which shows the electric current-displacement characteristic in the actuator which concerns on embodiment of this invention.

Explanation of symbols

9 Upper guide (support)
15 Holder 16 Optical member 17 Sphere 18 Base (support)
20 Energizing members 29 to 31 Pressure adjusting member

Claims (8)

A holder for holding an optical member;
A support for holding the holder so as to be movable in the optical axis direction;
A plurality of spheres arranged between the holder and the support and supporting the holder;
A biasing member that biases the holder in a direction substantially perpendicular to the optical axis via at least one of the plurality of spheres;
An actuator comprising: a pressure adjusting member that adjusts a pressure applied to the holder from the biasing member.   The actuator according to claim 1, wherein the biasing member is an elastic member.   The actuator according to claim 1, wherein the biasing member is formed integrally with the support and has a space between the support and the support.   The said pressurization adjustment member is bending the said biasing member to the said holder side or the said support body side in the direction substantially perpendicular | vertical with respect to the said optical axis, The any one of Claims 1-3 characterized by the above-mentioned. The actuator according to item.   The actuator according to any one of claims 1 to 4, wherein the pressurizing member is an adhesive or a pin installed between the support and the urging member.   The said pressurization adjustment member is a coil with which a magnet or an electric current flows, and is installed in each of the said support body and the said urging | biasing member, The any one of Claims 1-5 characterized by the above-mentioned. Actuator. The actuator according to any one of claims 1 to 6,
An optical member held by the holder;
An imaging device comprising: an imaging element that converts an image formed on an imaging surface by the optical member into an electrical signal.   An electronic device comprising the imaging device according to claim 7.

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