JP2009168919A - Lens module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens module capable of providing a stable moving speed by stabilizing a displacement quantity of a magnet of a driver, and to provide the lens module superior in assembling productivity, with a structure capable of correcting the magnetization direction when easily assembling even when the direction of the magnet in the driver is varied. <P>SOLUTION: This lens module has a housing 51, the driver, a lens holder 41, an optical lens 10 supported by or integrated into its holder, and a moving body 31. The driver is composed of a weight member 71, a piezoelectric ceramic element 11 having one end fixed to the weight member 71 and the magnet 21 adhered to its other end. The weight member 71 is fixed to the housing 51, and the moving body 31 is composed of a construction material adsorbable to the magnet 21, and is integrated into the lens holder 41. The magnet 21 is vibrated by vibration generated by the piezoelectric ceramic element 11, and the lens holder 41 is moved by driving slidingly the moving body 31 with the vibration of the magnet 21 as driving force. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lens module including an optical lens that can move in a predetermined direction, and is particularly suitable for a digital video camera, a digital camera, a mobile phone camera, or the like, and has an autofocus and zoom mechanism. The present invention relates to a lens module suitable for an optical apparatus.

  Conventionally, a mechanism for moving an optical lens along an optical axis is necessary to provide a camera with an autofocus or zoom function, and a method using an electromagnetic motor is generally known. However, in recent optical devices typified by digital cameras and camera-equipped mobile phones, miniaturization has rapidly progressed, and accordingly, a method of moving an optical lens by an electromechanical transducer such as a piezoelectric element from an electromagnetic motor is used. Technology has been proposed and is becoming mainstream.

  As such a well-known technique, for example, in Patent Document 1, a driving member that is frictionally engaged with a driven object or a member connected to the driven object and is movably supported by a stationary member, and its driving Piezoelectric element that is fixed to a member and fixed to a stationary member so that the other end does not move, and a piezoelectric element drive that applies a voltage to the piezoelectric element so that the speed of expansion differs from the speed of contraction And a driving device having the means.

  Patent Document 2 includes a driving member using a magnetic material, and a movable lens group frame that has an exciting member that excites the driving member and is driven by the driving member, and the driving member is an electromechanical conversion element. A driving mechanism driven by the above-described method is disclosed in Patent Document 3, which is a driving device including a driving mechanism formed by frictionally coupling a driven member to a driving member that is coupled to an electromechanical conversion element and displaced together with the electromechanical conversion element. , A means using a magnet as means for applying a pressing force for frictionally engaging the driving member and the driven member is shown. Patent Document 4 discloses a vibration shaft fixed to one end of a piezoelectric element, There is shown a drive mechanism that includes a collision element frictionally engaged with a vibration shaft and drives the collision element by driving the vibration shaft with a piezoelectric element, the vibration shaft being a magnet.

Japanese Patent No. 2633066 Japanese Patent Laid-Open No. 10-10401 JP 7-274546 A Japanese Patent Laid-Open No. 7-13061

  In any of the known techniques using the above-described method of moving an optical lens by an electromechanical conversion element, there is a structural problem in order to realize small and stable driving.

  For example, in the case of the method disclosed in Patent Document 1, a structure for supporting the driving member so as to be movable with respect to the stationary member is required, and the driving member and the driven object are connected using an elastic member such as a leaf spring. Since it is necessary to make frictional engagement, the structure of the lens module becomes complicated and it is difficult to reduce the size. Further, since it is difficult to control the frictional force, there is a problem that the moving speed of the driven object varies.

  In the case of the method disclosed in Patent Document 2, the magnetization direction of the excitation member is not fixed. For example, if the magnetization direction of the excitation member coincides with the movement direction of the optical lens, depending on the position of the optical lens, In the magnetic circuit formed with the drive member made of a magnetic material, the magnetic flux distribution becomes asymmetric in the vertical direction, which causes a problem that a significant difference is caused in the moving speed between when the lens is extended and when the lens is retracted. In addition, it is difficult to reduce the height of the drive member and the excitation member because of the structure.

  In the case of the method disclosed in Patent Document 3, there are many places where the moving shaft for moving the optical lens is substantially frictionally engaged with other members, and therefore the frictional force of the frictional engagement portion is controlled. Due to the complexity, there is a problem that it is difficult to stably drive the optical lens.

  In the case of the method disclosed in Patent Document 4, the shape of the contact portion of the impactor that frictionally engages with the drive shaft that is a magnet is an arc-shaped groove, and the surface is related to the coefficient of friction during friction engagement. Since it is difficult to manage the state, there is a problem that it is difficult to precisely position the optical lens when the same structure is developed to drive the lens.

  A lens module structure shown in FIG. 4 is conceivable as a lens module having a lens driving mechanism having a simple structure that can stabilize the moving speed of the lens as compared with the above driving mechanism. 4A and 4B show the basic configuration of the lens module. FIG. 4A is an external plan view from the top surface direction, and FIG. 4B is a side cross-sectional view in the CC line direction of FIG. is there. In FIG. 4, one end of the piezoelectric ceramic element 1 in the vibration displacement generation direction is bonded to the housing 50 and the other end is bonded to the magnet 21. The moving body 31 is provided integrally with the lens holder 41. Adsorbed by magnetic force. Furthermore, the lens holder 41 is movably supported by a guide pin 61 fixed to the housing 50 in order to prevent tilting or rotation. The piezoelectric ceramic element 1 is applied with a voltage that expands and contracts at different speeds during expansion and contraction, the magnet 21 is vibrated in parallel with the optical axis of the lens, and the moving body 31 is slidably driven using the vibration of the magnet 21 as a driving force. By doing so, the lens holder 41 is moved in the optical axis direction.

  In this driving method, stable driving and miniaturization can be obtained with a simple configuration as compared with the driving mechanisms described in Patent Documents 1 to 4 described above. However, since the driving body composed of the piezoelectric ceramic element 1 and the magnet 21 is adhered to the housing 50 as a stationary member, the elastic modulus and weight of the housing 50 affect the driving. In addition, since the center of gravity of the entire drive body is present in the vibrating piezoelectric ceramic element 1, there is a problem that the center of gravity varies and the amount of displacement of the magnet becomes small or the amount of displacement varies. .

  In addition, it is ideal that the direction of the magnet when viewed from the upper surface of FIG. 4A, that is, the direction of the magnetization direction is toward the moving body or the center of the lens. If the relative position between the housing and the housing is different, the relative angle between the magnetizing direction of the magnet of the driving body adhered and fixed to the housing 50 and the moving body varies, and the moving body 31 also has the varying magnetization direction. Since the force is applied in the direction, an excessive force may be applied to the guide pin 61, the frictional force between the guide pin 61 and the lens holder 41 increases, and the moving speed of the moving body decreases, and further movement There is a problem that becomes unstable.

  In this situation, a first object of the present invention is to provide a lens module that can stabilize the amount of displacement of a magnet of a driving body and obtain a stable moving speed. In addition, the second problem of the present invention is to provide a lens module having a structure capable of easily correcting the magnetization direction during assembly even when the direction of the magnet in the driving body varies, and having excellent assembly productivity. It is to provide.

  In order to solve the above problems, a lens module according to the present invention includes a stationary member, a driving body, a lens holder, an optical lens supported or integrated with the lens holder, and a moving body, and the driving body. Is composed of a weight member, an electromechanical conversion element having one end fixed to the weight member, and a magnet bonded to the other end of the electromechanical conversion element, and the weight member is fixed to the stationary member, and the movable body Is made of a material that can be attracted to the magnet and integrated with the lens holder, and vibrates the magnet by vibration generated by the electromechanical transducer, and uses the vibration of the magnet as a driving force to move the moving body. It has a function of moving the lens holder by sliding driving.

  The electromechanical transducer may include a piezoelectric element having electrodes at both ends and a protective layer disposed between the electrode and the weight member.

  The center of gravity of the entire driving body is preferably located in the protective layer of the electromechanical transducer or the weight member.

  In addition, the weight member may have a columnar shape, and in particular, in order to achieve the second problem of the present invention, it is desirable that the weight member has a columnar shape or a regular polygonal columnar shape.

  In the present invention, as described above, the weight member is bonded to the electromechanical conversion element to constitute the driving body, and the weight member is directly fixed to the stationary member, so that the center of gravity of the driving body is stabilized, and the center of gravity is further improved. The position of the magnet is positioned closer to the weight member than the portion directly excited by electricity of the electromechanical transducer, so that the amount of displacement of the magnet becomes equal to the amount of displacement generated in the electromechanical transducer, and the movement of the moving body Speed can be improved and driving can be stabilized.

  Furthermore, when a cylindrical or regular polygonal columnar weight member is used as the weight member, when the drive body is bonded to the housing, the drive body is rotated so that the magnetization direction of the magnet does not deviate from the optimum direction. By adhering and fixing to the housing, it is possible to easily correct misalignment of component parts, and to obtain a lens module with excellent productivity.

  A structure is also conceivable in which a vibration damping member is inserted between the weight member and the stationary member to prevent transmission of vibration to the stationary member without directly fixing the weight member to the stationary member. Due to the presence of the damping member, the amount of displacement of the magnet becomes small, and the position of the center of gravity becomes unstable.

  Hereinafter, embodiments and examples of the present invention will be described with reference to the drawings.

  FIG. 1 shows a basic configuration of a first embodiment of a lens module according to the present invention. FIG. 1 (a) is a plan view showing an appearance from the upper surface direction, and FIG. It is side surface sectional drawing in the AA line direction of 1 (a). In FIG. 1, a housing 51 that is a stationary member, a driving body, a lens holder 41, an optical lens 10 supported or integrated with the lens holder 41, and a moving body 31 are provided. The piezoelectric ceramic element 11, which is an electromechanical conversion element having one end fixed to the weight member 71, and the magnet 21 bonded to the other end of the piezoelectric ceramic element 11, and the weight member 71 is fixed to the housing 51. The moving body 31 is made of a material that can be attracted to the magnet 21 and is integrated with the lens holder 41. The magnet 21 is vibrated by vibration generated in the piezoelectric ceramic element 11, and the lens holder 41 is moved by slidingly moving the moving body 31 using the vibration of the magnet 21 as a driving force.

  With this structure, the piezoelectric ceramic element 11 is applied with a voltage that expands and contracts at different speeds during expansion and contraction, vibrates the magnet 21 in parallel with the optical axis, and moves the moving body 31 in the expansion and contraction direction. The holder 41 is moved in the optical axis direction.

  Here, FIG. 2 shows a cross-sectional view of the driving body in the present embodiment. In FIG. 2, the piezoelectric ceramic element 11 has a piezoelectric element 13 having electrodes 12 at both ends and a protective layer 14 covering the electrodes 12 from the outside of both ends. The protective layers are a magnet 21 and a weight member 71, respectively. It is glued to. Further, since the center of gravity of the entire driving body is set so as to be located in the protective layer 14 or the weight member 71 on the weight member 71 side, in this embodiment, as shown in FIG. The shape of the weight member 71 is a columnar shape having a right isosceles triangle shape as viewed from above so that the weight member 71 can be efficiently arranged in the corner space of the housing 51 and the weight of the weight member 71 can be maximized.

  FIG. 3 shows the basic configuration of the second embodiment of the lens module according to the present invention. FIG. 3 (a) is a plan view showing the appearance from the top surface direction, and FIG. It is side surface sectional drawing in the BB line direction of 3 (a). The configuration of the lens module of the present embodiment is basically the same as that of the lens module of the first embodiment shown in FIG. 3, but only the shape of the weight member 72 is different. In the present embodiment, the weight member 72 has a cylindrical shape.

  In the second embodiment, when the driving body is bonded and fixed to the housing 51, the shape of the weight member 72 that is the base portion is a cylinder, so that the rotation of the driving body can be adjusted at the bonding position in the housing 51, The direction of the magnet, that is, the magnetization direction can be easily adjusted. The shape of the weight member 71 in the first embodiment is not a regular polygon or a symmetrical shape such as a circle, so the side wall of the housing 51 becomes an obstacle and cannot be adjusted by rotating the driving body.

  Next, specific examples of the lens module according to the first embodiment of the present invention and the lens module according to the second embodiment will be described. As the piezoelectric ceramic element 11, a piezoelectric multilayer ceramic element having a cross section of 1.0 mm × 1.0 mm and a height of 1.5 mm was used. This piezoelectric multilayer ceramic element has a protective layer made of a ceramic material having a thickness of 0.1 mm outside the electrodes at both ends. This piezoelectric multilayer ceramic element generates a displacement of approximately 0.12 μm when a voltage of ± 3 V is applied. A neodymium magnet 21 having a surface of 1.2 mm × 1.5 mm and a height of 1.0 mm Ni-plated was bonded to one end of the piezoelectric multilayer ceramic element with a thermosetting epoxy resin. Further, at the other end of the piezoelectric multilayer ceramic element, as an example of the first embodiment, as a weight member, tungsten alloy having a height of 1.3 mm and a columnar shape of a right isosceles triangle with a side of 2.2 mm. Were bonded with thermosetting epoxy resin to complete the driving body. Further, a housing 51 made of polycarbonate was produced, and the driving body was bonded to the position shown in FIG. 1 with an epoxy resin.

  A moving body 31 made of stainless steel SUS430 and having an outer diameter of 8.5 mm, an inner diameter of 7.5 mm, and a height of 1.5 mm was produced. The moving body 31 was bonded to a lens holder 41 made of polycarbonate with an epoxy resin.

  If the center of gravity of the entire driving body is a static calculation, it can be calculated by the following formula when calculating the distance from the interface between the piezoelectric multilayer ceramic element and the weight member assuming that the parts are homogeneous. If it becomes a negative value, the position of the center of gravity exists on the weight member side from the interface between the piezoelectric multilayer ceramic element and the weight member.

  [{Magnet mass x magnet height ÷ 2 + piezoelectric ceramic element mass x (magnet height + piezoelectric ceramic element height ÷ 2) + weight mass x (magnet height + piezoelectric ceramic element height + weight height ÷ 2)} ÷ Driver mass (magnet mass + piezoelectric ceramic element mass + weight mass)]-(magnet height + piezoelectric ceramic element height)

In the case of the first embodiment, in order for the center of gravity of the entire driving body to be located in the protective layer or weight member on the weight member side, the magnet density is 7.6 g / cm ³ and the density of the piezoelectric multilayer ceramic element is When 9.8 g / cm ³ and the weight density are 18.5 g / cm ³ , the weight mass is 0.582 g or more. That is, the weight height is calculated to be 1.3 mm or more from the area of a right isosceles triangle having a side of 2.2 mm.

  In the example of the lens module of the second embodiment, a cylinder having a diameter of 1.5 mm and a height of 1.5 mm was used as the weight member. In this case, in order to position the center of gravity of the entire drive body in the protective layer or weight member on the weight member side as in the first embodiment, the weight weight is required to be 0.582 g or more and φ1.5 mm The height of the circle is required to be 1.5 mm or more.

  200 lens modules of the above-described examples of the first and second embodiments are manufactured, a sawtooth waveform of ± 3 V AC voltage is applied to the piezoelectric ceramic element 11, and the lens holder 41 is reciprocated in the optical axis direction. About the case where it moved, the displacement amount of the magnet 21 and the reciprocal average speed of the lens holder 41 were measured. The direction of movement was reversed by reversing the direction of the sawtooth waveform. For comparison, the lens module configured as shown in FIG. 4 was also evaluated by preparing and evaluating 200 lens modules having the same structure as that of the above embodiment except for the weight member.

  Table 1 summarizes the results of evaluation tests for three types of lens modules manufactured as examples and comparative examples of the above-described embodiments.

  From Table 1, in the comparative example, the displacement amount of the magnet is small, and the variation is large. In addition, the average speed of the moving body is small, and the variation is large. On the other hand, in the first embodiment of the present invention, compared to the comparative example, the amount of displacement of the magnet is dramatically improved, the variation is small and the amount of displacement is stable, the average speed of the moving body is improved, and the variation is also large. Smaller results were obtained. On the other hand, in the second embodiment of the present invention, it can be seen that both the displacement amount and its variation are further improved.

  As described above, according to the present invention, since the displacement amount of the magnet approaches and stabilizes the displacement amount of the electromechanical transducer, the speed of the moving body is improved, and variations in the displacement amount and the movement speed are reduced. The

  Also, by making the weight member a columnar shape or a regular polygonal columnar shape, it is possible to correct the displacement of the relative position of the lens holder and the housing and the displacement of the bonding direction of the magnet of the driving body when the driving body is fixed. Therefore, it is possible to produce a lens module with less variation in moving speed. As a result, the processing cost is reduced, the handling becomes easy, and a lens module excellent in assembly productivity can be obtained.

  Needless to say, the present invention is not limited to the above-described embodiments and examples, and the design can be changed according to the purpose and application. For example, the materials, structures, shapes, etc. of piezoelectric ceramic elements, magnets, weight members, housings, lens holders, etc., which are electromechanical conversion elements, can be redesigned according to the required shape and performance, and conventional lenses Compared with a module, even if the piezoelectric element does not have a protective layer, it is possible to improve the variation in the displacement and moving speed of the magnet.

1 shows a basic configuration of a first embodiment of a lens module according to the present invention, FIG. 1A is an external plan view from the top surface direction, and FIG. 1B is a line AA direction of FIG. Side surface sectional drawing. Sectional drawing of the drive body in 1st embodiment. 3 shows a basic configuration of a second embodiment of the lens module according to the present invention, FIG. 3A is an external plan view from the top surface direction, and FIG. 3B is a BB line direction of FIG. Side surface sectional drawing. 4 shows a basic configuration of a lens module having a lens driving mechanism having a structure capable of stabilizing the moving speed, FIG. 4A is an external plan view from the upper surface direction, and FIG. 4B is a CC view of FIG. Side surface sectional drawing in a line direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 11 Piezoelectric ceramic element 10 Optical lens 12 Electrode 13 Piezoelectric element 14 Protective layer 21 Magnet 31 Moving body 41 Lens holder 50, 51 Housing 61 Guide pins 71, 72 Weight member

Claims (5)

  An electric machine comprising a stationary member, a driving body, a lens holder, an optical lens supported or integrated with the lens holder, and a moving body, the driving body having a weight member and one end fixed to the weight member The lens holder is composed of a conversion element and a magnet bonded to the other end of the electromechanical conversion element, the weight member is fixed to the stationary member, and the moving body is composed of a material that can be attracted to the magnet. And having the function of moving the lens holder by oscillating the magnet by the vibration generated by the electromechanical transducer and slidingly driving the movable body using the vibration of the magnet as a driving force. A lens module characterized by that.   The lens module according to claim 1, wherein the electromechanical conversion element includes a piezoelectric element having electrodes at both ends and a protective layer disposed between the electrode and the weight member.   3. The lens module according to claim 1, wherein the center of gravity of the entire driving body is located in a protective layer of the electromechanical conversion element or the weight member.   The lens module according to claim 1, wherein the weight member has a columnar shape.   The lens module according to claim 1, wherein the weight member has a columnar shape or a regular polygonal columnar shape.

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