JP2011061977A - Driver, image acquisition device, electronic apparatus and control method of driver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress generation of errors, at a position of a lens holder after being moved. <P>SOLUTION: A driver 150 is provided with: a piezoelectric element 50 expanded and contracted in accordance with a drive voltage; a transmission shaft 51 receiving vibration occurring in the piezoelectric element 50; a housing 20 with which the transmission shaft 51 is engaged in a state where the transmission shaft 51 is slidable; a lens holder 31 which holds at least one lens and is displaced with respect to the housing 20, in synchronizing with the piezoelectric element 50 and the transmission shaft 51; and a drive voltage generating circuit 82 supplying drive voltage to the piezoelectric element 50. The drive voltage generating circuit 82 supplies the drive voltage to the piezoelectric element 50, based on switching pulses which are intermittently generated during at least first and second periods. The switching pulse is changed from the first period to the second period without being temporally divided. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a drive device, an image acquisition device, an electronic apparatus, and a drive device control method.

  In recent years, imaging devices such as cameras have been incorporated into a wide variety of products. When a camera is mounted on a small electronic device such as a mobile phone or a notebook computer, it is strongly required to reduce the size of the camera itself.

  An autofocus lens may be incorporated in the camera. In this case, downsizing of the actuator that displaces the lens is strongly desired. As a small actuator, one that moves a moving object by driving a piezoelectric element is known.

  Patent Document 1 discloses an optical element feeding device that can suppress vibration during driving and has high reliability. Specifically, it is disclosed that the drive control unit makes the drive speed near the end of driving slower than the previous drive speed.

JP 2009-4014 A

  By the way, in particular, in the type of actuator in which the lens holder, the piezoelectric element, and the transmission shaft are displaced in synchronization, there may be a loss in the amount of movement of the lens holder when the movement of the lens holder is started. Specifically, as shown in FIG. 32, when driving of the lens holder is started under a predetermined driving condition, the lens holder may not be sufficiently displaced at the start of movement, and movement loss may occur. It is not easy to stop the moving lens holder with high accuracy, and there may be a loss in the amount of movement of the lens holder even when the movement of the lens holder is stopped.

  When the lens holder is moved to a desired position, for example, a focus position, the lens holder may pass the focus position or may not reach the focus position with a single movement instruction. In this case, it is necessary to execute movement control of the lens holder several times. Unless the position of the lens holder is initialized, the error included in the current position of the lens holder increases due to the above-described reason as the number of movement instructions of the lens holder increases.

  In order to arrange the lens holder with respect to a desired position, it is conceivable that the moving speed of the lens holder is reduced as it approaches the desired position, and the position of the lens holder is appropriately controlled by feedback control. However, if the lens holder stops when changing the moving speed of the lens holder, an error will still occur in the current position of the lens holder for the reasons described above.

  If the error included in the current position of the lens holder increases, it may take time to move the lens holder to the in-focus position, and the performance of the camera module incorporating this actuator may deteriorate. There is.

  As is clear from the above description, there is a strong demand to suppress the occurrence of errors in the position of the lens holder after movement. In particular, there is a strong demand to suppress the occurrence of errors in the position of the lens holder after moving with a speed change. An object of the present invention is to suppress occurrence of an error in the position of the lens holder after movement.

  In the driving device according to the present invention, a piezoelectric element that expands and contracts in accordance with a driving voltage, a driving shaft that receives vibration generated by the piezoelectric element, and the driving shaft that is slidable are engaged with each other. A fixed-side member, a lens holding body that holds at least one lens and is displaced relative to the fixed-side member in synchronization with the piezoelectric element and the drive shaft, and supplies the drive voltage to the piezoelectric element A driving voltage supply unit, wherein the driving voltage supply unit applies the driving voltage to the piezoelectric element based on switching pulses generated intermittently at least in the first and second periods. The switching pulse is changed from the first period to the second period without being divided in time.

  The switching pulse is intermittently supplied at least in the first and second periods, and is changed from the first period to the second period without being divided in time. Therefore, the speed of the lens holder, which is a moving object, is changed without being divided in time, and continues to move in a desired direction without being divided in time. By avoiding the lens holder from being stopped as much as possible, it is possible to effectively suppress an error in the position of the lens holder.

  The drive voltage preferably oscillates between the first and second voltage levels.

  When the driving voltage swings between the first and second voltage levels in a relatively short time, the lens holder is displaced with respect to the fixed side member, and the first and second voltage levels are relative to each other. When the driving voltage is amplified over a long period of time, it is preferable that the lens holder is not substantially displaced with respect to the fixed side member.

  The drive voltage supply unit may include a switching pulse generation unit that generates the switching pulse, and a drive voltage generation unit that includes a plurality of switching elements whose operation states are determined according to the switching pulse.

  The apparatus may further include a control unit that controls an operation state of the drive voltage supply unit, and the control unit controls the drive voltage supply unit so that the lens holder gradually decelerates as the target position is approached. .

  An image acquisition apparatus according to the present invention includes any one of the driving apparatuses described above and an imaging unit that captures an image input via the lens.

  An electronic apparatus according to the present invention includes the above-described image acquisition device.

  The control method of the drive device according to the present invention includes a piezoelectric element that expands and contracts according to a drive voltage, a drive shaft that receives vibration generated by the piezoelectric element, and the drive shaft that is slidable. A fixed holding member, a lens holding member that holds at least one lens and is displaced with respect to the fixed side member in synchronization with the piezoelectric element and the drive shaft; and the drive for the piezoelectric element. A method of controlling a driving device comprising a driving voltage supply unit for supplying a voltage, the step of supplying a switching pulse intermittently at least in first and second cycles, and the piezoelectric based on the supplied switching pulse Supplying the driving voltage to the element, and changing the period of the switching pulse from the first period to the second period without providing a time interval. .

  When the driving voltage swings between the first and second voltage levels in a relatively short time, the lens holding body is displaced with respect to the fixed-side member, and the relative between the first and second voltage levels. When the driving voltage is amplified over a long period of time, the lens holding member is preferably not displaced with respect to the stationary member.

  According to the present invention, it is possible to suppress an error from occurring in the position of the lens holder after movement.

1 is a schematic exploded perspective view of a camera module according to a first embodiment of the present invention. 1 is a schematic perspective view of a camera module according to a first embodiment of the present invention. It is a mimetic diagram showing a schematic structure of an imaging module concerning a 1st embodiment of the present invention. It is a schematic perspective view of the housing | casing which concerns on 1st Embodiment of this invention. 1 is a schematic perspective view of a lens unit according to a first embodiment of the present invention. It is a schematic exploded perspective view of the axis | shaft holding | maintenance part which concerns on 1st Embodiment of this invention. It is a schematic perspective view of the axis | shaft holding | maintenance part which concerns on 1st Embodiment of this invention. It is a schematic perspective view of the axis | shaft holding | maintenance part which concerns on 1st Embodiment of this invention. It is a schematic side view of the axis | shaft holding | maintenance part which concerns on 1st Embodiment of this invention. It is a schematic perspective view of the axis | shaft holding | maintenance part which concerns on 1st Embodiment of this invention. It is a schematic top view of the axis | shaft holding | maintenance part which concerns on 1st Embodiment of this invention. 1 is a schematic side view of a lens unit according to a first embodiment of the present invention. 1 is a schematic cross-sectional schematic diagram of a lens unit according to a first embodiment of the present invention. It is a schematic perspective view which shows the attachment method of the shaft holding part with respect to the housing | casing which concerns on 1st Embodiment of this invention. It is a schematic partial top view of the camera module which concerns on 1st Embodiment of this invention. 1 is a schematic top view of a camera module according to a first embodiment of the present invention. 1 is a schematic cross-sectional schematic diagram of a camera module according to a first embodiment of the present invention. 1 is a schematic cross-sectional schematic diagram of a camera module according to a first embodiment of the present invention. 1 is a schematic diagram of a mobile phone according to a first embodiment of the present invention. It is a schematic block diagram which shows the structure of the drive part for driving the drive device which concerns on 1st Embodiment of this invention. 1 is a schematic circuit diagram of a drive voltage generation circuit according to a first embodiment of the present invention. It is a table | surface for demonstrating operation | movement of the drive voltage generation circuit which concerns on 1st Embodiment of this invention. It is a schematic timing chart which shows the relationship between each waveform which concerns on 1st Embodiment of this invention, and the movement state of a lens. It is a schematic explanatory drawing which shows the relationship between expansion / contraction of the piezoelectric element which concerns on 1st Embodiment of this invention, and the displacement of a lens holder. It is explanatory drawing for demonstrating the influence which adjustment of the duty ratio of the switching pulse which concerns on 1st Embodiment of this invention has on the displacement of a lens holder. It is a table | surface which shows the result of having evaluated the operation state of the actuator which concerns on 1st Embodiment of this invention. It is a timing chart which shows the change of the moving speed of the lens holder which concerns on 1st Embodiment of this invention. It is a timing chart which shows the change of the moving speed of the lens holder which concerns on a comparative example. It is the schematic which shows the camera module which concerns on a comparative example. It is a table | surface which shows the result of having evaluated the operation state of the actuator which concerns on a comparative example. It is explanatory drawing which shows the lens movement characteristic for every type of actuator. It is explanatory drawing which shows the operation | movement loss at the time of the movement start of a lens holder.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Each embodiment is simplified for convenience of explanation. Since the drawings are simple, the technical scope of the present invention should not be interpreted narrowly based on the drawings. The drawings are only for explaining the technical matters, and do not reflect the exact sizes or the like of the elements shown in the drawings. The same elements are denoted by the same reference numerals, and redundant description is omitted. Words indicating directions such as up, down, left, and right are used on the assumption that the drawing is viewed from the front.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIGS. 1 and 2, a camera module (image acquisition device) 150 includes a wiring board 10, a connector 11, an imaging module 12, a housing (envelope) 20, a lens unit (lens component) 30, and a lid. 60 (envelope). As shown in FIG. 3, the imaging module 12 includes a transparent substrate 13a and an image sensor (imaging device, imaging means) 13b. An imaging region 13c is arranged on the upper surface of the image sensor 13b.

  As shown in FIG. 1, a connector 11 is disposed at one end of the wiring board 10. An imaging module 12 is disposed at the other end of the wiring board 10. On the imaging module 12, the housing 20, the lens unit 30, and the lid 60 are arranged in this order. The housing 20 functions as a stationary member that does not move when viewed from the lenses L1 to L3 (see FIG. 17) that are moving objects. Similarly, the lid 60, the imaging module 12, and the wiring board 10 also function as fixed-side members.

  The wiring board 10 is a flexible sheet-like wiring board. The wiring board 10 functions as a transmission path for a control signal input to the image sensor 13b and a video signal output from the image sensor 13b. The wiring board 10 functions as a transmission path for driving voltage input to the piezo element 50.

  The connector 11 is a part for electrically and mechanically connecting the camera module 150 to the main device.

  As described above, the imaging module 12 includes the transparent substrate 13a and the image sensor 13b.

  The transparent substrate 13a is a plate-like member that is substantially transparent to input light. The top view shape of the transparent substrate 13a is a square. The image sensor 13b is bump-connected to the back surface of the transparent substrate 13a.

  The image sensor 13b is a general solid-state image sensor such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor. The imaging region 13c of the image sensor 13b has a plurality of pixels arranged in a matrix on the XZ plane. Each pixel accumulates electric charge according to the amount of input light by photoelectric conversion. The electric charge accumulated in each pixel is read from each pixel by transfer control and supplied to the subsequent circuit.

  The housing 20 is mounted on the wiring board 10. The housing 20 stores the imaging module 12 in the lower space, and stores the lens unit 30 in the upper space. By adopting the housing 20, the camera function can be modularized. The lower end surface of the housing 20 is fixed to the wiring substrate 10 with a black adhesive. Thereby, it is possible to suppress the entry of extraneous light into the housing 20. The housing 20 is manufactured by molding a black resin, for example.

  The lid 60 is attached to the housing 20. As a result, the lens unit 30 is confined in the housing 20. The lid 60 is preferably attached to the housing 20 by screws. The lid 60 can be attached to and detached from the housing 20 by fixing the lid 60 to the housing 20 with screws instead of adhesively fixing. As a result, it is possible to remove the cause of the failure of the camera module 150 determined to be defective in the operation test after the test. For example, the yield of the camera module can be improved by removing dust that has entered the imaging surface of the image sensor 13b after the operation test. The lid 60 is manufactured by molding a resin, for example.

  As shown in FIG. 4, the housing 20 includes a side wall (side wall part) 21, a partition wall (partition wall part) 22, a beam part 23, a beam part 24, a rail (guide part) 25, a pedestal (base part) 26, and a hole part. 27, a guide post 28, and an outlet 29.

  The side wall 21 is a cylindrical portion having a square shape in a top view in which the side walls 21a to 21d are continuous. The wall thickness of the side wall 21 is set to 0.3 mm to 0.6 mm. The partition wall 22 is a plate-like portion extending inward from the side wall 21. The wall thickness of the partition wall 22 is set to 0.3 mm to 0.6 mm similarly to the side wall 21. By the partition wall 22, a storage space for the lens unit 30 and a storage space for the imaging module 12 are formed in the housing 20. The partition wall 22 is provided with an opening OP2 for optically connecting the upper and lower storage spaces.

  The partition wall 22 is provided with a pedestal 26 on which a later-described shaft holding portion 40 (see FIGS. 5 and 6) is placed. The base 26 is provided with a hole 27. The hole 27 is disposed closer to the side wall 21 than the opening OP2. The hole 27 a is provided near the end of the side wall 21. The hole 27b is provided in the vicinity of the inner corner between the side wall 21a and the side wall 21d.

  In order to increase the strength of the side wall 21, a beam portion 23 is provided at an inner corner between the side wall 21a and the side wall 21b. The beam portion 23 includes an end portion 23a, a flat plate portion 23b, and an end portion 23c. When viewed from the flat plate portion 23b, the end portion 23a extends toward the side wall 21a and is connected to the side wall 21a. When viewed from the flat plate portion 23b, the end portion 23c extends toward the side wall 21b and is connected to the side wall 21b. The beam portion 23 is connected to the upper surface of the partition wall 22. A space is formed between the beam portion 23 and the side walls 21a and 21b.

  In order to increase the strength of the side wall 21, a beam portion 24 is provided at an inner corner between the side wall 21c and the side wall 21d. The beam portion 24 has a base portion 24a, a trunk portion 24b, and an end portion 24c.

  The base end of the base 24a is connected to the side wall 21c. The distal end of the base portion 24a is connected to the proximal end of the body portion 24b. The base 24a extends in a direction away from the side wall 21c. The body portion 24 b extends along the outer periphery of the lens unit 30. Similarly, the end portion 24 c extends along the outer periphery of the lens unit 30. The trunk | drum 24b is thicker than the base 24a and the edge part 24c. As a result, when the casing 20 is molded, the casing 20 can be easily detached from the mold by an extrusion pin or the like. The beam portion 24 is connected to the partition wall 22. A space is formed between the beam portion 24 and the side walls 21c and 21d.

  The rail 25 is disposed at a corner between the side wall 21b and the side wall 21c. The rail 25 is a columnar body extending along the side wall 21. The movement of the lens unit 30 is stabilized by the rail 25.

  Guide pillars (wiring guide portions) 28 are provided inside the side wall 21d. The guide column 28 is a columnar body extending along the side wall 21d. The wiring is positioned between the guide column 28 and the side wall 21d. The guide pillar 28 is a member for positioning the wiring drawn in the housing 20.

  An outlet 29 is provided in the side wall 21c. The wiring in the housing 20 is routed between the guide pillar 28 and the side wall 21d, between the beam portion 24 and the side wall 21d, between the beam portion 24 and the side wall 21c, and is drawn out of the housing 20 through the outlet 29. This is connected to the wiring board 10.

  As shown in FIG. 5, the lens unit 30 includes a lens holder (lens holder) 31, a piezo element (piezoelectric element) 50, a transmission shaft (drive shaft) 51, and a shaft holder 40.

  The lens holder 31 is a cylindrical member and holds the lenses L1 to L4 (see FIG. 17). An opening OP <b> 1 is formed in the upper plate portion of the lens holder 31. The upper plate portion of the lens holder 31 functions as an optical stop. On the outer periphery of the lens holder 31, a connecting portion 32 to which the transmission shaft 51 is connected is provided. The connecting portion 32 includes support plates 32 a and 32 b that fix and support the transmission shaft 51. Note that the lens unit 30 may be grasped without including the shaft holding unit 40.

  The lens unit 30 is movable along the y axis (axis line that coincides with the optical axis of the lenses L1 to L3) in accordance with the driving of the piezo element 50. However, the shaft holding unit 40 is fixed to the housing 20 and does not move in accordance with the driving of the piezo element 50. By adjusting the arrangement height of the lenses L1 to L3 with respect to the imaging surface of the image sensor 13b, a subject image can be formed on the imaging surface of the image sensor 13b as intended.

  The piezo element 50 and the transmission shaft 51 are fixed to each other via an adhesive. The transmission shaft 51 is connected to the lens holder 31 via the connecting portion 32. Specifically, the transmission shaft 51 is press-fitted into the openings of the support plates 32 a and 32 b of the connecting portion 32.

  When the piezo element 50 is fixed to the housing 20, the piezo element 50 may be disposed to be inclined with respect to the flat surface of the housing 20. The same applies to the case where the transmission shaft 51 is fixed to the housing 20. In the present embodiment, the transmission shaft 51 is fixed to the lens holder 31, and the piezo element 50 is fixed to the lens holder 31 via the transmission shaft 51. Therefore, the placement error of the piezo element 50 and the transmission shaft 51 with respect to the housing 20 does not become a problem.

  The lens holder 31, the piezo element 50, and the transmission shaft 51 are fixed in relative positional relationship, and are movable relative to the shaft holding portion 40 that functions as a fixed-side member.

  The piezo element 50 is a general piezoelectric element in which ceramic layers (piezoelectric layers) are laminated. The side surfaces of the piezo element 50 function as a pair of electrode terminals. For example, when one electrode terminal is grounded and a driving voltage is applied to the other electrode terminal, the piezo element 50 expands and contracts in the Y-axis direction.

  The transmission shaft 51 is a rod-like body whose longitudinal direction is the y-axis direction. The transmission shaft 51 is fixed to the upper surface of the piezo element 50 via an adhesive. Note that the transmission shaft 51 may be fixed to the piezo element 50 by a method other than an adhesive. The method of connecting the piezo element 50 and the transmission shaft 51 is arbitrary, and the transmission shaft 51 and the piezo element 50 may be connected to each other by fitting.

  The transmission shaft 51 transmits the vibration generated in the piezo element 50 to the shaft holding unit 40. The shaft holding part 40 holds the transmission shaft 51 in a slidable state and is fixed to the housing 20. Accordingly, the vibration generated in the piezo element 50 causes the piezo element 50, the transmission shaft 51, and the lens holder 31 to be displaced with respect to the housing 20 and the shaft holding unit 40.

  The transmission shaft 51 is desirably lightweight and highly rigid. The transmission shaft 51 is made of a material having a specific gravity of 2.1 or less. More preferably, the transmission shaft 51 is made of a material having a specific gravity of 2.1 or less and an elastic modulus of 20 GPa or more. More preferably, the transmission shaft 51 is made of a material having a specific gravity of 2.1 or less and an elastic modulus of 30 GPa or more. Thereby, the resonance frequency can be shifted to the high frequency side, and a continuous usable frequency band can be obtained.

  The transmission shaft 51 is preferably molded from glassy carbon, fiber reinforced resin, or epoxy resin. Particularly preferred are glassy carbon composites containing graphite, fiber reinforced resins and glass containing carbon, and epoxy resin composites containing carbon.

  A rail receiving portion 35 is provided on the outer peripheral surface of the lens holder 31. The rail receiving portion 35 receives the rail 25 provided in the housing 20. By fitting the rail receiving portion 35 to the rail 25, the movement of the lens holder 31 is stabilized.

  On the outer peripheral surface of the lens holder 31, support plates 32a and 32b extending outward are disposed at a predetermined interval in the y-axis direction. The support plates 32a and 32b are formed with openings into which the transmission shaft 51 is inserted. The support plates 32a and 32b may be separated from the lens holder 31.

  The support plate 32a fixedly supports the transmission shaft 51. The opening formed in the support plate 32 a is slightly narrower than the diameter of the transmission shaft 51. The transmission shaft 51 can be fixed to the support plate 32a by fitting the transmission shaft 51 by applying pressure to the opening formed in the support plate 32a. The hole diameter of the support plate 32b is the same as that of the support plate 32a.

  By adopting the above-described configuration, the transmission shaft 51 can be tightly held by the support plates 32a and 32b. In other words, the degree of vibration transmission between the transmission shaft 51 and the support plates 32a and 32b can be increased. In this way, the lens holder 31 can be displaced efficiently.

  When adopting a method other than press-fitting, the same effect as described above can be obtained by appropriately selecting an adhesive. For example, it is preferable to employ a thermosetting epoxy adhesive.

  A shaft holding portion 40 is disposed between the support plates 32a and 32b. These assembling methods are arbitrary. For example, the transmission shaft 51 is inserted into these members in a state where the shaft holding portion 40 is disposed between the support plates 32a and 32b.

  By disposing the shaft holder 40 between the support plates 32a and 32b, the movement range of the lens holder 31 can be regulated. However, the transmission shaft 51 may be supported by one of the support plate 32a and the support plate 32b without being limited to such two-point support.

  The shaft holding part 40 holds the transmission shaft 51 in a slidable state along the y axis. The shaft holding part 40 and the transmission shaft 51 are in frictional engagement with each other. The configuration of the shaft holder 40 will be described later.

  As described above, the lens holder 31 holds the lenses L1 to L3. The lens L1 is disposed in the lens holder 31 through an alignment process. The lens L2 and the lens L3 are arranged in the lens holder 31 without undergoing the alignment process. That is, the lens L1 is a lens that requires higher positional accuracy than the lenses L2 and L3.

  The method of incorporating the lenses L1 to L3 into the lens holder 31 is arbitrary. For example, the lens L3 and the lens L2 are laminated in this order, the lens L1 is aligned on the lens L2, the lens L3, the lens L2, and the lens L1 are bonded and fixed, and then the laminated body of the lenses L1 to L3. Is preferably press-fitted into the lens holder 31. The lenses L1 to L3 may be incorporated into the lens holder 31 by a method other than press fitting.

  The configuration of the shaft holding unit 40 will be described with reference to FIGS. As shown in FIGS. 6 and 7, the shaft holding portion 40 includes a main body portion 41, a presser plate (plate member) 42, a spring (elastic body) 43, and a presser plate (plate member) 44. In the direction away from the transmission shaft 51, the presser plate 42, the spring 43, and the presser plate 44 are arranged in this order.

  In the main body 41, a space 41a and a space 41b are formed. The space 41 a houses the presser plate 42 and the spring 43. The space 41 b accommodates the presser plate 44. Moreover, the main-body part 41 has the convex parts 45a and 45b.

  The presser plate 42 is a plate-like member having a left end portion 42a, a body portion 42b, and a right end portion 42c. The spring 43 is a general coil spring. The presser plate 44 is a rectangular plate member.

  The presser plate 42, the spring 43, and the presser plate 44 are sequentially pushed into the space formed in the main body 41. The presser plate 42 and the spring 43 are accommodated in a space 41 a formed in the main body 41. The presser plate 44 is accommodated in a space 41 b formed in the main body 41.

  The presser plate 42, the spring 43, and the presser plate 44 are positioned by bonding and fixing the presser plate 44 to the main body 41. Specifically, the spring 43 is confined in the space of the main body 41 by the presser plate 44 and biases the holding plate 42 toward the transmission shaft 51. The presser plate 42 is urged toward the transmission shaft 51 by a spring 43. The transmission shaft 51 is urged inward by the spring 43 through the presser plate 42 and is held between the main body 41 and the presser plate 42. In other words, the transmission shaft 51 and the shaft holding portion 40 are in frictional engagement with each other.

  By reducing the width along the y-axis of the end portion of the presser plate 42, the vertical displacement of the presser plate 42 inside the main body 41 while suppressing the width along the y-axis of the main body 41 from being increased. Can be regulated. By suppressing the height (width along the y-axis) of the main body portion 41, a sufficient movement range of the lens unit 30 can be ensured.

  The holding plate 42 is preferably made of a metal material. For example, the holding plate 42 may be formed of a metal material such as a zinc alloy or an aluminum alloy. Accordingly, it is possible to effectively suppress the generation of wear powder from the press plate 42 due to friction between the transmission shaft 51 and the press plate 42.

  The diameter of the spring 43 is substantially the same as or slightly smaller than the width of the presser plate 42. The specific configuration of the spring 43 is arbitrary, and other types of elastic bodies (plate springs, resin rubber, etc.) may be used. The main body 41 is manufactured by molding a resin with a mold. For example, the holding plates 42 and 44 are manufactured by press molding of a metal plate or a resin plate.

  The main body 41 is preferably made of a metal material. When the main body 41 is made of resin, wear powder may be generated due to friction with the transmission shaft 51. In order to avoid the occurrence of such a problem, here, the main body 41 is manufactured by forming a zinc alloy. In addition, you may employ | adopt not only a zinc alloy but an aluminum alloy and another metal material.

  As shown in FIGS. 8 to 10, the shaft holding portion 40 has a thin portion 41p and a thick portion 41q. The thickness (width along the y axis) TH1 of the thin portion 41p is smaller than the thickness (width along the y axis) TH2 of the thick portion 41q. The shaft holding part 40 holds the transmission shaft 51 at the thin part 41p, and is fixed to the housing 20 at the thick part 41q. By adopting this configuration, it is possible to stably fix the shaft holding portion 40 to the housing 20 while sufficiently securing the movement range of the lens unit 30.

  The thin portion 41p is provided with an opening OP10 through which the transmission shaft 51 is inserted. The thin wall portion 41p is provided with a guide groove 41g for fitting the end portions 42a and 42c of the presser plate 42 and guiding the movement of the presser plate 42. The convex portions 45a and 45b described above are provided on the lower surface of the thick portion 41q. A side wall 41r provided corresponding to the side wall 21 of the housing 20 is provided on the upper surface of the thick portion 41q. When the shaft holding portion 40 is fixed to the housing 20, the side wall 21 of the housing 20 and the side wall 41 r of the shaft holding portion 40 are continuous, thereby stabilizing the fixing of the lid 60 to the housing 20. Invasion of dust from the outside to the inside of the body 20 can be effectively suppressed.

  As shown in FIG. 11, projecting portions 47a and 47b projecting toward the transmission shaft 51 are provided on the inner surface of the thin portion 41p where the opening OP10 is formed. Each protrusion 47a, 47b is formed by partially making the inner surface of the opening of the main body 41 a flat surface.

  The transmission shaft 51 is abutted and held at three points by the pressing plate 42, the protruding portion 47a, and the protruding portion 47b between the main body portion 41 and the pressing plate 42. Thereby, the transmission shaft 51 can be stably held. Note that the three contact points are at approximately equal intervals and are sequentially shifted by 120 degrees. Thereby, the transmission shaft 51 can be held more stably.

  FIG. 12 shows a side view of the lens unit 30, and FIG. 13 shows a schematic cross-sectional view of the lens unit 30.

  As shown in FIG. 13, the width along the axis Lx1 of the presser plate 44 is narrower than the width along the axis Lx1 of the presser plate 42. As a result, the spring 43 can be disposed at a position closer to the inner surface of the housing 20, and the camera module 150 can be downsized.

  The spring 43 biases the presser plate 42 in a direction (direction along the axis Lx2) that forms 90 degrees with respect to the arrangement direction (direction along the axis Lx1) of the transmission shaft 51 viewed from the lens holder 31. Thereby, the arrangement space of the shaft holding portion 40 can be effectively reduced, and the camera module 150 can be reduced in size. The angle formed by the axis Lx1 and the axis Lx2 is not limited to 90 degrees. The angle formed by the axis Lx1 and the axis Lx2 may be 45 to 135 degrees.

  As schematically shown in FIG. 14, the shaft holding unit 40 is attached to the housing 20. Holes 27 a and 27 b are provided on the upper surface (mounting surface) of the pedestal 26 provided in the partition wall 22 of the housing 20. Further, convex portions 45 a and 45 b are provided on the lower surface of the main body portion 41 of the shaft holding portion 40. The convex portion 45 a of the main body portion 41 is fitted into the hole portion 27 a of the partition wall 22. Similarly, the convex portion 45 b of the main body portion 41 is fitted into the hole portion 27 b of the partition wall 22. In the present embodiment, the shaft holding portion 40 can be positioned with high accuracy by surface contact between the lower surface of the main body portion 41 and the upper surface of the pedestal 26.

  The side wall 21 of the housing 20 is provided with a notch 21e. By injecting resin into the space between the housing 20 and the shaft holding portion 40, the shaft holding portion 40 can be fixed to the housing 20.

  In the present embodiment, the shaft holding portion 40 is placed on the partition wall 22 of the housing 20, and both are fixed by fitting the hole portion 27 and the convex portion 45. By adopting this configuration, it is possible to avoid the problem of warping of the side wall 21 that becomes a problem when the shaft holding portion 40 is fixed to the side wall 21 of the housing 20. This is because the partition wall 22 is a thin plate-like portion like the side wall 21, but has a shorter length than the side wall 21 and does not warp like the side wall 21.

  In the present embodiment, a pedestal 26 is provided for the partition wall 22, and the shaft holding portion 40 is fixed on the pedestal 26. By adopting this configuration, the shaft holding unit 40 can be stably placed on the housing 20 by surface contact between the upper surface of the base 26 and the surface of the shaft holding unit 40. By molding the upper surface of the base 26 with high accuracy and molding the mounting surface of the shaft holding portion 40 with high accuracy, the positional stability of the shaft holding portion 40 can be effectively increased.

  In the present embodiment, the pedestal 26 is disposed in the vicinity of the side wall 21. Thereby, the stability of the shaft holder 40 can be effectively increased. This is because the partition wall 22 is connected to the side walls 21a and 21d in the vicinity of the corner of the housing 20, and the partition wall 22 is unlikely to be deformed such as warpage.

  As shown in FIG. 14, by attaching the shaft holding portion 40 to the housing 20, the main body portion 41 is fitted into the notch 21 e provided on the side wall 21 of the housing 20 as shown in FIG. 15. . In this way, the housing 20 can be effectively downsized. In addition, as shown in FIG. 15, by sticking the seal member 70 to the housing 20 and the shaft holding portion 40 from the outside of the housing 20, it is effective that dust enters the housing 20 from the outside. Can be suppressed. The seal member 70 is, for example, a flexible black tape.

  As shown in FIG. 15, the housing 20 has equal horizontal width and vertical width. That is, the width W1 = the width W2, and the top view shape of the housing 20 is a square shape. In this case, the optical axis of the lens is set near the intersection of the diagonal lines of the housing 20. Accordingly, the optical axis of the lens can be easily positioned by positioning the housing 20. In addition, according to the trial results of the inventors, the vertical width and the horizontal width of the housing 20 can be effectively reduced as compared with the conventional case by adopting the above-described shaft holding portion 40.

  Moreover, as shown in FIG. 11, the outlet 29 is provided in the corner adjacent to the corner of the housing 20 in which the shaft holding portion 40 is disposed. Thereby, the length of the lead wire drawn in the housing 20 can be effectively shortened.

  The configuration of the camera module 150 will be further described with reference to FIGS. 16 to 18. Note that FIG. 16 is a top view of the camera module 150. FIG. 17 is a schematic cross-sectional view of the camera module 150 taken along x17-x17. FIG. 18 is a schematic cross-sectional view of the camera module 150 taken along x18-x18.

  As shown in FIGS. 17 and 18, the height (width along the y-axis) of the stacked body of the piezoelectric element 50 and the transmission shaft 51 is equal to or less than the height of the lens holder 31 (width along the y-axis). Thereby, in order to ensure the movement range of the lens holder 31, it is possible to effectively suppress an increase in the height (width along the y-axis) of the housing 20. As a result, the camera module 150 can be reduced in height.

  The image sensor 13b is bump-mounted on the transparent substrate 13a. A plurality of solder bumps (not shown) are arranged between the transparent substrate 13a and the image sensor 13b. By forming solder bumps on the transparent substrate 13a and mounting the image sensor 13b thereon, the transparent substrate 13a and the image sensor 13b are laminated. A wiring pattern is formed in advance on the back surface of the transparent substrate 13a. In this way, the position between the image sensor 13b and the transparent substrate 13a is fixed, and electrical connection between the two is ensured. Note that the imaging surface of the image sensor 13b is disposed on the transparent substrate 13a side.

  The distance (separation distance) between the image sensor 13b and the transparent substrate 13a is determined by the size of the solder bump described above. By appropriately controlling the size of the solder bumps, it is possible to accurately position the image sensor 13b and the transparent substrate 13a. Further, since the positioning is performed by a plurality of solder bumps, the distance between the image sensor 13b and the transparent substrate 13a is averaged.

  The transparent substrate 13 a is bump-connected to the wiring substrate 10. That is, the transparent substrate 13a is fixed and electrically connected to the wiring substrate 10 via the solder bumps. In this way, the image sensor 13b is electrically connected to the wiring substrate 10 via the transparent substrate 13a.

  A space is secured between the image sensor 13 b and the wiring substrate 10 by the solder bumps between the transparent substrate 13 a and the wiring substrate 10. In other words, the solder bump between the transparent substrate 13 a and the wiring substrate 10 functions as a spacer for forming a space between the image sensor 13 b and the wiring substrate 10.

  Ribs (position restricting portions) are formed on the back side of the partition wall 22 that separates the upper space and the lower space of the housing 20. Thus, when the housing 20 is disposed on the transparent substrate 13a, the transparent substrate 13a can be pressed from above and the transparent substrate 13a can be suitably positioned.

  In order to appropriately position the transparent substrate 13a, ribs facing the side surfaces of the transparent substrate 13a may be formed in the housing 20. Accordingly, when the housing 20 is disposed on the transparent substrate 13a, the position of the transparent substrate 13a can be preferably regulated from the lateral direction, and the transparent substrate 13a can be suitably positioned. In addition, you may regulate the arrangement position of the transparent substrate 13a from the horizontal direction directly with the housing | casing 20, without providing such a rib.

  A reinforcing plate 15 is disposed under the wiring board 10. The reinforcing plate 15 is made of a resin material such as polyimide. The reinforcing plate 15 is black. By arranging the reinforcing plate 15, it is possible to suitably prevent the external light from entering the camera module 150. In addition, in order to further suppress the adverse effect of extraneous light, the black wiring board 10 is employed.

  Next, further description will be given with reference to FIGS.

  The camera module 150 is mounted in the mobile phone 90 shown in FIG. The mobile phone 90 has an upper body 91, a lower body 92, and a hinge 93. The upper main body 91 and the lower main body 92 are both plastic plate members and are connected via a hinge 93. The upper main body 91 and the lower main body 92 are configured to be freely opened and closed by a hinge 93. When the upper body 91 and the lower body 92 are closed, the mobile phone 90 is a flat plate member in which the upper body 91 and the lower body 92 are overlapped.

  The upper main body 91 has a display unit 94 on the inner surface thereof. The display unit 94 displays information (name, telephone number) for identifying the called party, address information stored in the storage unit of the mobile phone 90, and the like. A liquid crystal display device is incorporated under the display unit 94.

  The lower main body 92 has a plurality of buttons 95 on its inner surface. The operator of the cellular phone 90 operates the button 95 to open the address book, make a call, set the manner mode, and operate the cellular phone 90 as intended. The operator of the mobile phone 90 activates the camera module 150 in the mobile phone 90 based on operating this button 95.

  With reference to FIG. 20, the system configuration (configuration of the actuator drive unit) for operating the camera module 150 will be described. As shown in FIG. 20, the output of the image acquisition unit 80 is connected to a controller (control unit) 81. The output of the controller 81 is connected to a drive voltage generation circuit (drive voltage supply unit) 82. The output of the drive voltage generation circuit 82 is connected to the vibration source 83. The image acquisition unit 80 is equivalent to the above-described image sensor 13b. The vibration source 83 is equal to the piezo element 50 described above.

  The controller 81 is a CPU incorporated in the mobile phone 90 and generates various commands by executing a program. The controller 81 activates the function of the camera module in response to the operation of the mobile phone 90 by the operator.

  The controller 81 has a function of adjusting the moving speed of the lens holder 31. The controller 81 determines whether or not the lens holder 31 is in the in-focus position based on the processing for the image transmitted from the image acquisition unit 80, and in order to bring the lens holder 31 into the in-focus state, The movement direction and movement amount of the holder 31 are calculated. When moving the lens holder 31 from a position away from the focus position to the focus position, the controller 81 controls the drive voltage generation circuit 82 so that the lens holder 31 moves at high speed. When moving the lens holder 31 to the in-focus position within a distance close to the in-focus position, the controller 81 controls the drive voltage generation circuit 82 so that the lens holder 31 moves at a low speed. The drive voltage generation circuit 82 supplies a drive voltage to the vibration source 83 in accordance with a control signal supplied from the controller 81. In the embodiment described later, the specific operation contents of the controller 81 will be described.

  The configuration and operation of the drive voltage generation circuit 82 will be described with reference to FIGS.

  As illustrated in FIG. 21, the drive voltage generation circuit (drive voltage supply unit) 82 includes a switching pulse generation circuit (switching pulse generation unit) 85 and a drive voltage generation unit including switches SW1 to SW4. The drive voltage generator further includes current sources CS1 and CS2 and a power source PS.

  The output of the controller 81 is connected to the switching pulse generation circuit 85. The switching pulse generation circuit 85 generates a switching pulse having a frequency corresponding to the control signal transmitted from the controller 81 and supplies the switching pulse to the switches SW1 to SW4. The drive voltage generator supplies the drive voltage to the piezo element 50 by controlling the switches SW1 to SW4 according to the switching pulse.

  A switch SW1, a current source CS1, and a switch SW2 are connected in series between the power supply PS and the ground potential GND. A switch SW3, a current source CS2, and a switch SW4 are connected in series between the power supply PS and the ground potential GND. A node between the current source CS1 and the switch SW2 is connected to a node between the switch SW3 and the current source CS2. The node between the current source CS1 and the switch SW2 and the node between the switch SW3 and the current source CS2 are connected to one end of the piezo element PZ. The other end of the piezo element PZ is connected to the switch SW2, the switch SW4, and the ground potential GND. The switches SW1 to SW4 are switching elements such as MOS (Metal Oxide Semiconductor) transistors.

  As shown in FIG. 22, the switching pulse generation circuit 85 controls the operation states of the switches SW1 to SW4. The switching pulse generation circuit 85 has terminals T1 to T4. The operating states of the switches SW1 to SW4 are determined by the switching pulses VS1 to VS4 output from the terminals T1 to T4. For example, when the switching pulse is at a high level, the switches SW1 to SW4 are turned on. When the switching pulse is at a low level, the switches SW1 to SW4 are turned off.

  In the first state shown in FIG. 22, the piezo element PZ is rapidly charged by the current source CS1. In the second state, the piezo element PZ discharges slowly. In the third state, the piezo element PZ is slowly charged by the current sources CS1 and CS2. In the fourth state, the piezo element PZ discharges rapidly. By repeatedly switching between the first state and the second state, the lens holder 31 is displaced in the forward direction (object side) one side. By repeatedly switching between the third state and the fourth state, the lens holder 31 is displaced in the reverse direction (image sensor side).

  Further description will be given with reference to FIGS.

  As shown in FIG. 23, the switching pulse VS1 from the terminal T1 of the switching pulse generation circuit 85 is supplied to the switch SW1, and the switching pulse VS2 from the terminal T2 is supplied to the switch SW2. In response to this, the drive voltage VW1 is applied to the piezo element PZ. In response to this, the lens holder 31 is displaced in the forward direction. In FIG. 23, the displacement of the lens holder 31 is schematically indicated by an arrow. That is, the lens holder 31 is displaced between time t1 and time t2, and is not displaced between time t2 and time t3. The same applies to other periods.

  Note that the switching pulse VS1 and the switching pulse VS2 are in an inverted relationship. Since one switching pulse may be generated by inverting the other switching pulse, the circuit configuration of the switching pulse generation circuit 85 can be simplified. The time interval between time t1 and time t2 is sufficiently shorter than the time interval between time t2 and time t3. This point is clear from the description regarding the duty ratio described later.

  In the present embodiment, the lens holder 31 is displaced at a time corresponding to the supply time of the switching pulse SP included in the switching pulses VS1 and VS2. According to the study by the inventors, the expansion and contraction of the piezo element 50 and the displacement of the lens holder 31 are linked as shown in FIG. The drive voltage VW1 rises steeply between time t20 (corresponding to time t1 in FIG. 23) and time t21 (corresponding to time t2 in FIG. 23). The piezo element PZ expands in response to the rise of the drive voltage VW1. The lens holder 31 is displaced in a direction away from the shaft holding portion 40 in accordance with the extension of the piezo element PZ. Between time t21 and time t25 (corresponding to time t3 in FIG. 23), the drive voltage VW1 falls slowly. In response to the fall of the drive voltage VW1, the piezo element 50 contracts relatively slowly. At this time, the piezo element PZ stays in place due to its inertia. Since the switching pulse is a high frequency, the lens holder 31 holds the moving force between the times t2 and t3.

  In the actuator according to the present embodiment, the lens holder 31 is displaced with respect to the shaft holding portion 40 when the piezo element 50 is rapidly expanded. In other words, the lens holder 31 is not displaced with respect to the shaft holder 40 when the piezo element 50 contracts slowly. In this case, in order to displace the lens holder 31 efficiently, it can be said that the piezo element 50 is extended in a short time by narrowing the pulse width of the switching pulse SP. Considering that it is necessary to ensure the discharge time of the current accumulated in the piezo element 50, it can be said that the duty ratio of the switching pulse should be set small.

  More specifically, as shown in FIG. 25, the lens holder 31 is efficiently displaced by setting the duty ratio of the switching pulse from α% to β% (where β% <α%). be able to. By displacing the lens holder 31 more efficiently, the lens holder 31 can be displaced at a higher speed. The duty ratio D can be calculated from the pulse width / cycle. As shown in FIG. 25A, it is calculated by ta / Ta = α. As shown in FIG. 25B, it is calculated by tb / Tb = β. ta and tb are pulse widths. Ta and Tb are periods.

  The setting of the switching pulse will be described with reference to FIG. In FIG. 26, the duty ratio of the switching pulse is in the range of 4% to 40%. The frequency band of the switching pulse was 40 kHz to 200 kHz. If the duty ratio is 2% or less, it is expected that the level of the drive voltage applied to the piezo element will decrease. Therefore, here, the duty ratio is set to a value of 2% or more (that is, the minimum duty ratio = 4%).

  In addition, about the test result, it evaluates in three steps of (triangle | delta) *. The characteristics of the actuator improve in the order of ○> △> ×. In the case of ○, the actuator operates at a high speed of 1 mm / s or more without any problem. In the case of Δ, the operating characteristics of the actuator deteriorate compared to the case of ○. In the case of ×, it is difficult to ensure the normal operation of the actuator.

  As shown in FIG. 26, according to the prototype evaluation result of the actuator according to the present embodiment, if the duty ratio D of the switching pulse is 25%, the actuator is normally operated on condition that an appropriate frequency is selected. Can do. Compared with the case where the duty ratio D exceeds 30%, the waveform of the drive voltage becomes steep, and the lens holder 31 can be displaced efficiently.

  More preferably, the duty ratio D of the switching pulse may be 20%. As a result, in addition to the same effects as described above, the selectable frequency band can be expanded. The degree of freedom in design is improved by expanding the selectable frequency band. Further, adverse effects (deterioration of yield, etc.) due to fluctuations in the frequency of the actually generated switching pulse can be avoided.

  Even more preferably, the duty ratio D of the switching pulse is 15% or less, 10% or less, 8% or less, or 6% or less. The selectable frequency band can be further expanded, and the same effect as described above can be obtained. The results shown in FIG. 26 are based on the assumption that the lens holder 31 is displaced in the forward direction. When the lens holder 31 is displaced in the reverse direction, the duty ratio D becomes a different value. For example, in order to obtain the same result as the duty ratio D = 10% applied in the forward direction, the duty ratio D = 90% is set in the reverse direction.

  In the present embodiment, by setting the duty ratio D of the switching pulse to be small, the lens holder 31 can be displaced efficiently, and the selectable frequency band can be significantly expanded. The degree of freedom in design is improved by expanding the selectable frequency band. Further, adverse effects (deterioration of yield, etc.) due to fluctuations in the frequency of the actually generated switching pulse can be avoided. If the switching pulses VS1 and VS2 are set in a high frequency band, the lens holder 31 can be displaced at a higher speed than in the prior art. Thereby, the operating characteristics of the actuator can be improved.

  With reference to FIG. 27, a process in which the moving speed of the lens holder 31 is changed based on a command from the controller 81 will be described. The controller 81 calculates the current position of the lens holder 31 with respect to the in-focus position based on the image data transmitted from the image acquisition unit 80, and sends the moving direction and moving speed of the lens holder 31 to the drive voltage generation circuit 82. Instruct. The drive voltage generation circuit 82 generates a switching pulse having a predetermined frequency based on a command from the controller 81, supplies this to a predetermined switching element, and thereby supplies a drive voltage to the vibration source 83.

  As shown in FIG. 27, the lens holder 31 continuously moves at a high speed until time t30, and continuously moves at a low speed after time t30. In the present embodiment, when the lens holder 31 is far from the in-focus position, the lens holder 31 is first moved at a high speed, and when the lens holder 31 is close to the in-focus position, the lens holder 31 is moved at a low speed. As a result, the time required for focusing can be reduced as a whole. Note that by moving the lens holder 31 at a low speed, it is possible to more reliably determine whether or not the lens holder 31 is in the in-focus position.

  Until time t30, based on the command of the controller 81, the switching pulse generation circuit 85 supplies the switching pulse to the switches SW1 and SW2 as described in FIG. The switching pulse has a duty ratio of 10% and a frequency of 120 kHz.

  When the time t30 has elapsed, the switching pulse generation circuit 85 supplies switching pulses having different frequencies to the switches SW1 and SW2 as described with reference to FIG. The switching pulse after time t30 has a duty ratio of 7% and a frequency of 80 kHz.

  In the present embodiment, the moving speed of the lens holder 31 is changed by modulating the frequency of the switching pulse. At this time, the frequency of the switching pulse is changed without providing a time interval. That is, no time interval is provided between the frequency 120 kHz period (high-speed movement period) and the frequency 80 kHz period (low-speed movement period). The lens holder 31 maintains a state of continuously moving before and after the switching pulse change time without completely stopping once when the frequency of the switching pulse is changed. As described with reference to FIG. 32, when the lens holder 31 is completely stopped, a movement loss occurs during the initial movement of the lens holder 31, and an error occurs in the position of the lens holder 31 after the movement. End up. In this embodiment, the frequency modulation of the switching pulse is executed without providing a time interval. Thereby, it is possible to suppress an error from occurring in the position of the lens holder 31 after the movement.

  FIG. 28 shows the case of the reference example. In the case of the reference example shown in FIG. 28, the position of the lens holder 31 is adjusted based on the change in the number of switching pulses per unit time without modulating the frequency of the switching pulses. In this case, the lens holder 31 remains in the moving state until time t35. However, after time t35, the lens holder 31 is also completely stopped in response to the supply of the switching pulse being stopped. Although the amount of movement of the lens holder 31 can be assumed to some extent depending on the number of switching pulses, as described at the beginning, an error may occur in the position of the lens holder 31 when the movement is started and when the movement is stopped. As a result, in order to bring the lens holder 31 into focus, it may be necessary to repeat the movement of the lens holder 31 toward the object side and the movement toward the imaging plane side.

  In the present embodiment, as the lens holder 31 approaches the in-focus position, the moving speed is reduced by frequency modulation of the switching pulse, and no time interval is provided during frequency modulation. Thereby, the lens holder 31 is kept in the moving state over the period before and after the speed change to avoid stopping the lens holder 31 completely. Thereby, it is possible to effectively suppress a loss in the movement amount of the lens holder 31 and to displace the lens holder 31 with higher accuracy. In this embodiment, since the selection range of the frequency of the switching pulse is expanded, the moving speed of the lens holder 31 can be changed in a wide range.

  In the present embodiment, a piezo element 50 and a transmission shaft 51 are attached to the lens holder 31. If the weight of the moving object increases, it may not be easy to control the position with high accuracy. As in the present embodiment, in the type of actuator in which the lens holder 31, the piezo element 50, and the transmission shaft 51 are displaced together, as described above, the moving speed of the lens holder 31 is adjusted by frequency modulation of the switching pulse. Moreover, not providing a time interval when changing the moving speed is very effective in increasing the positional accuracy of the lens holder 31 after the movement.

  Next, a comparative example will be described with reference to FIGS. In FIG. 30, the operation results of the actuator are evaluated in the same manner as in FIG. In the case of the comparative example, a circuit similar to that in FIG. 21 is adopted.

  FIG. 29 shows a camera module according to a comparative example. As shown in FIG. 29, the movable part MU is formed by the lens holder 31 and the shaft holding part 40. The piezo element 50 is fixed to the wiring board 10. The transmission shaft 51 is fixed with respect to the piezo element 50. The lens holder 31 and the shaft holder 40 move together in accordance with the driving of the piezo element 50.

  When the comparative example is compared with the present embodiment, the point that the piezo element PZ is driven with the sawtooth drive voltage VW1 is the same. However, the relationship between the waveform of the drive voltage VW1 and the timing at which the lens holder 31 is displaced differs between the two. That is, in the case of the present embodiment, the lens holder 31 is displaced when the waveform of the drive voltage VW1 changes in a short time. In the comparative example, the lens holder 31 is moved when the waveform of the drive voltage VW1 changes slowly. Displace. Therefore, in the case of the comparative example, it is required to ensure a sufficient period during which the waveform of the drive voltage VW1 changes slowly. In this case, it is not meaningful to set the duty ratio of the switching pulse small. This is because, in the case of the comparative example, when the waveform of the drive voltage VW1 changes sharply, the lens holder 31 is not substantially displaced.

  As shown in FIG. 30, in the comparative example, the selection range of the duty ratio of the switching pulse is narrow. In addition, the selection range of the frequency of the switching pulse is narrow. The selectable frequency band is narrow because, in the case of the comparative example, the piezo element 50 is coupled to the housing 20 and resonance occurs due to the system including the housing 20.

  As shown in FIG. 31, in the case of this embodiment, compared with the case of a comparative example, the frequency band of a switching pulse can be expanded on the conditions which set the switching pulse to desired duty ratio. This is because in this embodiment, the resonance frequency is shifted to the high frequency side. In this embodiment, the switching pulse can be set to a higher frequency as compared with the comparative example. Thereby, the lens holder 31 can be displaced at higher speed.

  When the selectable frequency band is narrow, it is difficult to displace the lens holder 31 due to the cause that the operating frequency deviates from the selected frequency band due to variations in characteristics of the piezo element alone or changes in the operating environment of the actuator. There is a risk. On the other hand, in this embodiment, the selectable frequency band itself is expanded. Therefore, it is possible to effectively suppress the frequency selected for some unexpected cause from being included in the resonance frequency band.

  The resonance frequency depends on the shape and weight of the housing and the bonding state between the piezoelectric element and the housing. The resonance frequency may be different for each product in which the drive device is incorporated. In a band where the resonance frequency exists, it may be difficult to accurately control the actuator. In other words, the determination of whether the actuator functions normally must wait for the actuator to be incorporated into the product. Depending on the setting error of the frequency of the switching pulse, the product yield may be reduced. In the present embodiment, occurrence of such a problem can be effectively suppressed.

[Example 1]
In the present embodiment, the lens holder 31 is moved at a high speed toward the target position, and after the lens holder 31 has passed the target position, the lens holder 31 is moved at a low speed in the opposite direction, and the lens holder 31 is disposed at the target position. As a result, the lens holder 31 can be arranged at a desired position in a short time.

  The movement control of the lens holder 31 can be realized by a program. Specifically, the controller 81 controls the moving speed of the lens holder 31 by designating the frequency of the switching pulse to the drive voltage generation circuit 82.

  First, the controller 81 controls the drive voltage generation circuit 82 so that the lens holder 31 is moved at high speed toward the target position. Next, the controller 81 detects that the lens holder 31 has passed the target position based on the output of the image acquisition unit 80. Next, the controller 81 controls the drive voltage generation circuit 82 so that the lens holder 31 moves at a low speed in the opposite direction. Next, the controller 81 determines whether or not the lens holder 31 has reached the target position.

  Whether or not the lens holder 31 has passed the target position can be realized by a program determination process. For example, it is possible to determine whether or not the lens holder 31 has passed the target position by comparing and evaluating the quality of images acquired at different timings.

  Also in this embodiment, the frequency of the switching pulse is changed without time division, and the moving speed of the lens holder 31 is changed. Thereby, it is possible to suppress an error from occurring in the position of the lens holder 31 after the movement.

[Example 2]
In this embodiment, the lens holder 31 is moved at a high speed toward the target position, and as the lens holder 31 approaches the target position, the moving speed of the lens holder 31 is decreased and the lens holder 31 is stopped at the target position. . As a result, the lens holder 31 can be arranged at a desired position in a short time.

  The movement control of the lens holder 31 can be realized by a program as in the first embodiment. The distance between the lens holder 31 and the target position can be detected by a determination process by a program. For example, the switching pulse may be gradually changed from a frequency of 120 kHz and a duty ratio of 10% to a frequency of 80 kHz and a duty ratio of 70%. Specific numerical values of the frequency and the duty ratio are arbitrary, and by appropriately setting these conditions, the lens holder 31 can be smoothly decelerated until the moving speed of the lens holder 31 becomes zero.

  Thus, by controlling the movement state of the lens holder 31, the lens holder 31 can be gradually decelerated as it approaches the target position. Also in the present embodiment, the frequency of the switching pulse is changed without time division, and the moving speed of the lens holder 31 is changed. Thereby, it is possible to suppress an error from occurring in the position of the lens holder 31 after the movement.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. The system configuration of the drive unit is arbitrary. A circuit for generating a switching pulse may be incorporated in the CPU. In the embodiment, the speed control of the lens holder 31 is realized by changing both the frequency of the switching pulse and the duty ratio, but it can also be realized by changing only one of them.

150 Camera module

DESCRIPTION OF SYMBOLS 10 Wiring board 11 Connector 12 Imaging module 13a Transparent substrate 13b Image sensor 13c Imaging area 15 Reinforcement board 20 Housing | casing 21 Side wall 22 Partition 23 Beam part 24 Beam part 25 Rail 26 Base 27 Hole part 28 Guide pillar 29 Exit 30 Lens unit 31 Lens holder 32 Connecting portion 35 Rail receiving portion 40 Shaft holding portion 41 Main body portion 42 Holding plate 43 Spring 44 Holding plate 45 Protruding portion 47 Protruding portion 50 Piezo element 51 Transmission shaft 60 Lid 70 Seal member

80 Image acquisition unit 81 Controller 82 Drive voltage generation circuit 83 Vibration source 85 Switching pulse generation circuit

Claims (9)

A piezoelectric element that expands and contracts according to the driving voltage;
A drive shaft that receives vibration generated in the piezoelectric element;
A fixed-side member engaged with the drive shaft in a state where the drive shaft is slidable;
A lens holder that holds at least one lens and is displaced relative to the stationary member in synchronization with the piezoelectric element and the drive shaft;
A drive voltage supply unit for supplying the drive voltage to the piezoelectric element;
A drive device comprising:
The drive voltage supply unit supplies the drive voltage to the piezoelectric element based on switching pulses generated intermittently at least in the first and second cycles,
The driving device, wherein the switching pulse is changed from the first period to the second period without being divided in time.   The drive device of claim 1, wherein the drive voltage swings between a first and a second voltage level. When the driving voltage swings in a relatively short time between the first and second voltage levels, the lens holding body is displaced with respect to the fixed side member,
3. The lens holder is not substantially displaced with respect to the fixed-side member when the drive voltage is amplified over a relatively long time between the first and second voltage levels. The drive device described in 1. The drive voltage supply unit includes:
A switching pulse generator for generating the switching pulse;
A drive voltage generation unit including a plurality of switching elements whose operation state is determined according to the switching pulse;
The drive device according to any one of claims 1 to 3, further comprising: A control unit for controlling an operation state of the drive voltage supply unit;
5. The drive device according to claim 1, wherein the control unit controls the drive voltage supply unit so that the lens holding body gradually decelerates as it approaches a target position. 6. . A driving device according to any one of claims 1 to 5,
Imaging means for capturing an image input via the lens;
An image acquisition apparatus comprising:   An electronic apparatus comprising the image acquisition device according to claim 6. A piezoelectric element that expands and contracts according to the driving voltage;
A drive shaft that receives vibration generated in the piezoelectric element;
A fixed side member engaged with the drive shaft in a state in which the drive shaft is slidable;
A lens holder that holds at least one lens and is displaced relative to the stationary member in synchronization with the piezoelectric element and the drive shaft;
A drive voltage supply unit for supplying the drive voltage to the piezoelectric element;
A method for controlling a drive device comprising:
Supplying a switching pulse intermittently at least in the first and second periods;
Supplying the drive voltage to the piezoelectric element based on the supplied switching pulse;
Changing the period of the switching pulse from the first period to the second period without providing a time interval;
A method for controlling a drive device comprising: When the driving voltage swings between the first and second voltage levels in a relatively short time, the lens holder is displaced with respect to the fixed side member,
9. The lens holding body is not substantially displaced with respect to the fixed-side member when the driving voltage swings between the first and second voltage levels over a relatively long time. A method for controlling the driving device according to claim 1.

Images