JP2008016079A - Driving device and optical disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correctly move and position a driving object in a driving device which moves and positions the driving object engaged with the device by using an electric-mechanical transducer element. <P>SOLUTION: This driving device has a driver 5D movably provided on a base 31B, a piezo-electric element 5C disposed to move the driver 5D, the driving object 31A having a first engaging section 5A and a second engaging section 5B and movably supported by the driver 5D and engaged with the 5A, 5B, and can change the moving amount of the object 31A with respect to the moving amount of the driver 5D by changing speed when the driver 5D moves by the piezo-electric element 5C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an object driving apparatus and an optical disk apparatus, and more particularly to an apparatus for moving a driven body using an electro-mechanical conversion element.

  Conventionally, as a mechanism for driving an optical element, a sawtooth wave drive pulse is supplied to an electro-mechanical conversion element (piezoelectric element) coupled with a drive shaft to displace the drive shaft in the axial direction, and frictionally coupled to the drive shaft. A piezoelectric actuator (driving device) that moves the driven member in the axial direction is known (for example, see Patent Document 1).

  FIG. 5 shows an example of a lens driving device to which such a known piezoelectric actuator is applied, and FIG. 6 is a sectional view taken along line VI-VI in FIG. FIG. 7 is a perspective view in which a part of the configuration of a similar lens driving device is cut away.

  The configuration will be described with reference to FIGS.

  Reference numeral 41 denotes a lens outer cylinder. A holding frame 42 of the first lens L1 is fixedly attached to the left end thereof, and a holding frame of the third lens L3 is formed on the right end thereof. Inside the lens outer cylinder 41, a holding frame 43 of the second lens L2 is disposed so as to be movable in the optical axis direction as will be described later.

  Reference numeral 44 denotes a drive shaft that drives the holding frame 43 of the second lens L2 in the optical axis direction. The shape of the drive shaft is not a round shaft, but a flat surface 44a in which the lower portion of the round shaft is flattened as shown in FIG. It has a shape (D-cut shape). As a result, the anti-rotation effect is obtained, and the anti-rotation shaft 61 as shown in FIG. 7 is not required. The drive shaft 44 is supported by the first flange portion 41 b of the lens outer cylinder 41 and the flange portion 42 b of the holding frame 42 so as to be movable in the optical axis direction, and one end thereof is formed on one surface of the electromechanical conversion element 45. Bonded and fixed.

  Reference numeral 45 denotes an electro-mechanical conversion element that changes its thickness in the thickness direction (left and right in the figure) and displaces the drive shaft 44 in the axial direction. One end surface of the electromechanical conversion element is bonded and fixed to the drive shaft 44, and the other end surface is a lens. It is bonded and fixed to the second flange portion 41 c of the outer cylinder 41.

  The holding frame 43 of the second lens L2 includes a contact member 43b extending downward, and a drive shaft 44 passes through the contact member 43b. A notch groove is formed on the lower surface of the contact member 43b. The contact member 43b and the drive shaft 44 are pressed against each other by a press contact spring 43c fitted between the notch groove and the upper surface of the contact member 43b, and are frictionally coupled with an appropriate frictional force.

  In the above configuration, when a drive pulse having a waveform composed of a gradual rising portion E1 and a subsequent rapid falling portion E2 as shown in FIG. 4 is applied to the electromechanical conversion element 45, the gradual rise of the driving pulse is applied. In the part E1, the electromechanical conversion element 45 is gently displaced in the thickness direction, and the drive shaft 44 is displaced in the direction of arrow a in the axial direction. For this reason, the contact member 43b of the lens holding frame 43, which is in frictional contact with the drive shaft 44 by the pressure contact spring 43c, also moves in the direction of arrow a. Therefore, the lens holding frame 43 can be moved in the direction of arrow a. .

  At the rapid fall portion E2 of the drive pulse, the electromechanical conversion element 45 rapidly undergoes contraction displacement in the thickness direction, and the drive shaft 44 is also displaced in the direction opposite to the arrow a in the axial direction. At this time, the contact member 43b of the lens holding frame 43 that is in pressure contact with the drive shaft 44 by the pressure contact spring 43c overcomes the friction force between the drive shaft 44 by the inertial force and substantially remains in that position. The holding frame 43 does not move.

  Note that the term “substantially” used herein refers to the driving time of the lens holding frame 43 and the drive shaft 44 while sliding between the contact member 43b of the lens holding frame 43 and the drive shaft 44 both in the direction of arrow a and in the opposite direction. It also means that it includes those that move in the direction of arrow a as a whole due to the difference. The type of movement is determined according to the given friction condition.

  By continuously applying the drive pulse having the above waveform to the electro-mechanical conversion element 45, the lens holding frame 43 can be continuously moved in the direction indicated by the arrow a.

  The movement of the lens holding frame 43 in the direction opposite to the arrow a can be achieved by applying a drive pulse having a waveform composed of a rapid rising portion and a subsequent gentle falling portion to the electro-mechanical conversion element 45.

According to this drive device, the contact member 43b of the lens holding frame 43 is fitted and frictionally coupled to the drive shaft 44 having a D-cut cross section, and the contact member is provided with the flat surface 44a on the lower surface of the drive shaft 44 as a guide surface. Since 43b is guided, it can move in the axial direction without rotating the lens holding frame 43, and it is not necessary to provide a guide shaft in addition to the drive shaft.
Japanese Patent Laid-Open No. 08-29658

  In the conventional piezoelectric actuator as shown in FIG. 5, the lens holding frame 43, which is a driven member, is supported by a drive shaft 44, which is another means for preventing rotation of the driven member as shown in FIG. The guide shaft 61 is not required. 7 are the same as those in FIG. 5, but the shape of the drive shaft 44b is cylindrical.

  However, in FIG. 5, in order to accurately move the lens holding frame 43 along the optical axis, it is necessary to configure the contact member 43b fitted to the drive shaft 44 with a sufficiently long length. If the contact member 43b corresponding to the length of the contact member 43b is not sufficiently long, when the lens holding frame 43 is moved, the lower part of the lens holding frame 43 is pitched back and forth with respect to the axial direction. There arises a problem that it cannot be accurately moved and positioned along the optical axis.

  Note that the above-described problem occurs not only when the optical element such as the lens holding frame is moved and positioned, but also when the driven body other than the optical element is moved and positioned.

  The present invention has been made in view of the above-described problems. In a driving apparatus that moves a driving member by an electro-mechanical conversion element and moves and positions a driven body engaged with the driving member, It is an object of the present invention to provide a drive device that can accurately move and position a drive body.

  According to a first aspect of the present invention, there is provided a drive member provided on the base member so as to be movable in a uniaxial direction, an electro-mechanical conversion element provided on the base member for moving the drive member, A first engagement portion that engages with the drive member; and a second engagement portion that engages with the drive member apart from the first engagement portion, and is engaged with each engagement portion. The driven member is supported by the driving member and is movable in the uniaxial direction with respect to the driving member, and the moving speed when the driving member moves by the electromechanical conversion element is changed. Thus, the driving device is configured such that the moving amount of the driven body changes with respect to the moving amount of the driving member.

  According to the second aspect of the present invention, the cross section of the plane perpendicular to the longitudinal direction is formed in a non-circular shape, and the drive member provided on the base member is movable in the longitudinal direction, and the expansion / contraction direction is An electro-mechanical machine in which one end portion in the expansion / contraction direction is provided integrally with the base member and the other end portion in the expansion / contraction direction is provided integrally with the drive member so as to be parallel to the longitudinal direction of the drive member. A conversion element, a first engagement portion that engages with the drive member with a first predetermined frictional force, and a second predetermined frictional force that engages with the drive member away from the first engagement portion. A second engaging portion that is supported by the driving member by being engaged with each of the engaging portions, and is movable with respect to the driving member in the longitudinal direction of the driving member. The drive by expansion and contraction of the electro-mechanical conversion element when a voltage is applied A drive device having a driven body that moves in accordance with the movement of the drive member when the movement speed of the member is low and that does not move even when the drive member moves when the movement speed is high. .

  According to a third aspect of the present invention, there is provided a spindle for rotating and driving the optical disc while holding a central portion of the optical disc, reading information recorded on the optical disc held on the spindle, and recording information on the optical disc. A laser generator for generating laser light for performing at least one of erasing information recorded on the optical disc and rewriting information recorded on the optical disc, and applying the generated laser light to the optical disc A pickup mechanism provided with an optical path for guiding, and a track moving means capable of moving and positioning the pickup mechanism in a radial direction of the optical disk held by the spindle together with a housing provided with the pickup mechanism. A frame provided integrally with a housing provided with the pickup mechanism And a cross section formed by a plane orthogonal to the longitudinal direction is formed in a non-circular shape, and the longitudinal direction is a direction intersecting with the radial direction of the optical disk held by the spindle and the optical disk held by the spindle The drive member provided on the frame body and the expansion / contraction direction are parallel to the longitudinal direction of the drive member so as to be perpendicular to the thickness direction and movable in the longitudinal direction. The electromechanical conversion element having one end portion in the expansion / contraction direction integrally provided on the frame body and the other end portion in the expansion / contraction direction integrally provided on the drive member, and a first engaging with the drive member. And a second engagement portion that is separated from the first engagement portion and engages with the drive member, and is supported by the drive member by engaging with each engagement portion. As the drive member moves A holding base that moves in the longitudinal direction of the drive member; and a laser beam that is provided on the holding base and that has passed through the optical path of the pickup mechanism when the holding base is positioned at one end in the moving direction. A first objective lens that irradiates the optical disk held by the laser, and a laser that is provided on the holding base and that has passed through the optical path of the pickup mechanism when the holding base is located on the other end side in the moving direction. An optical disk apparatus having a second objective lens that irradiates light onto the optical disk held by the spindle.

  According to the present invention, in the driving apparatus that moves the driving member by the electro-mechanical conversion element and moves and positions the driven body engaged with the driving member, the driven pair is accurately moved and positioned. There is an effect that can be.

  The driving device includes a driving member, an electromechanical conversion element, and a driven body.

  The drive member has a non-circular cross section (for example, a square shape) formed by a plane orthogonal to the longitudinal direction. The drive member is provided on the base member so as to be movable only in the longitudinal direction.

  The electro-mechanical conversion element is configured such that one end portion in the expansion / contraction direction is integrally provided on the base member so that the expansion / contraction direction is parallel to the longitudinal direction of the drive member, and the other end portion in the expansion / contraction direction is For example, the driving member is integrally provided at one end portion in the longitudinal direction.

  The driven body includes a first engagement portion and a second engagement portion, and is supported by the drive member by being engaged by the engagement portions, and the drive member in the longitudinal direction of the drive member. It is movable with respect to the drive member. In addition, the driven body has a moving speed of the driving member due to expansion and contraction of the electro-mechanical conversion element when a voltage is applied, as in the conventional driving device, depending on the engagement form of each engaging portion. When it is small, it moves in the moving direction of the driving member with respect to the base member according to the movement of the driving member, and when the moving speed is high, it does not move with respect to the base member even when the driving member moves. It has become.

  The first engagement portion is engaged with the drive member in a sliding pair with a first predetermined frictional force on one side in the longitudinal direction of the drive member, and the second engagement The portion is separated from the first engagement portion on the other side in the longitudinal direction of the drive member, and is engaged with the drive member in a sliding pair with a second predetermined frictional force.

  For example, the second engagement portion of the driven body is engaged with the drive member with a slightly smaller frictional force than the first engagement portion.

  The driving device is provided with electro-mechanical conversion element driving means. The electro-mechanical transducer driving means drives the electric-mechanical transducer so that the electro-mechanical transducer repeatedly expands and contracts in order to move the driven body in one direction or another direction opposite to the one direction. A voltage is applied to the mechanical conversion element.

  Here, the optical disk device 1 will be described as an example of the drive device.

  FIG. 1 is a diagram showing a schematic configuration of an optical disc apparatus 1 according to an embodiment of the present invention, FIG. 2 (a) is a diagram showing IIA-IIA in FIG. 1, and FIG. FIG. 2 is a diagram showing an IIB-IIB arrow view in FIG. 1, and FIG. 3 is a III arrow view in FIG.

  In the present specification, for convenience of explanation, one of the radial directions of the optical disk 6 held on the spindle 4 is referred to as an X-axis direction, which is a direction orthogonal to the X-axis direction and is attached to the spindle 4. A direction in contact with the circumferential direction of the held optical disk 6 is referred to as a Y-axis direction, and a direction orthogonal to the X-axis direction and the Y-axis direction (the thickness direction of the optical disk 6 held by the spindle 4) is referred to as a Z-axis direction. is there.

  The optical disk device 1 includes three semiconductor laser generators with different output wavelengths (in FIG. 1, other than one semiconductor laser generator 1A is omitted), and two objective lenses 2A and 2B with different numerical apertures. It has. The optical disc apparatus 1 uses various types of optical discs such as Blu-ray discs in addition to CDs and DVDs by appropriately switching between these semiconductor laser generators (semiconductor lasers) and objective lenses 2A and 2B. 6, at least one of reading information recorded on the optical disk 6, recording information on the optical disk 6, erasing information recorded on the optical disk 6, and rewriting information recorded on the optical disk 6 can be performed. ing.

  The optical disk apparatus 1 includes a main body housing (not shown). A disk tray (not shown) is provided in the main body housing so as to be freely inserted and removed, and a spindle 4 is provided. The spindle 4 rotates the optical disk 6 while holding the central portion of the thin disk-shaped optical disk 6.

  In addition, the optical disc apparatus 1 is provided with a pickup mechanism 3 and a track moving means 101. The pickup mechanism 3 receives the above-described semiconductor laser generator 1A and the like and the laser beam generated by the semiconductor laser generator 1A through an objective lens 2A or objective lens 2B (an optical disc held on the spindle 4). ) And an optical path (not shown) for guiding to 6.

  The track moving means 101 holds the pickup mechanism 3 on the spindle 4 together with the housing 3A in which the pickup mechanism 3 is provided in accordance with the position of recording information on the optical disk 6 held on the spindle 4. This is for moving and positioning the optical disk 6 in the radial direction (X-axis direction). As will be described in detail later, the track moving means 101 is constituted by, for example, a thread motor 103 and a lead screw 40 (see FIG. 8).

  The pickup mechanism 3 includes a lens switching drive unit (slide drive unit) for moving the objective lenses 2A and 2B in the Y-axis direction and switching the objective lenses 2A and 2B through which the laser light applied to the optical disc 6 passes. 5 is provided.

  The lens switching drive unit 5 includes a frame body 31B that is an example of a base member, a drive member 5D, an electro-mechanical conversion element (piezoelectric element) 5C, and a holding base 31A that is an example of a driven body. Has been. The frame 31B is integrally provided on the housing 3A in which the pickup mechanism 3 is provided using a fastener such as a bolt.

  The drive member 5D is provided on the frame body 31B so that the longitudinal direction is the Y-axis direction. Further, the drive member 5D has a cross section formed by a plane orthogonal to the longitudinal direction, for example, in a square shape. Furthermore, the drive member 5D is supported by the frame body 31B at or near both ends in the longitudinal direction, and can move relative to the frame body 31B only in the longitudinal direction (Y-axis direction) of the drive member 5D. Yes.

  The piezoelectric element 5C has one end in the expansion / contraction direction integrally attached to the frame 31B so that the expansion / contraction direction is parallel to the longitudinal direction (Y-axis direction) of the drive member 5D. One end of the drive member 5D in the longitudinal direction is integrally attached to the end. It is desirable that the central axis of the piezoelectric element 5C extending in the expansion / contraction direction (Y-axis direction) of the piezoelectric element 5C and the central axis extending in the longitudinal direction (Y-axis direction) of the driving member 5D coincide with each other.

  The holding base 31A includes a first engagement portion 5A and a second engagement portion 5B, and is supported by the drive member 5D when the drive member 5D is engaged with the engagement portions 5A and 5B. ing. And it is movable with respect to the drive member 5D only in the longitudinal direction (Y-axis direction) of the drive member 5D.

  The first engagement portion 5A is engaged with the drive member 5D by a first predetermined frictional force on one side in the longitudinal direction of the drive member 5D so as to form a sliding pair. The second engagement portion 5B is separated from the first engagement portion 5A on the other side in the longitudinal direction of the drive member 5D and is engaged with the drive member 5D by a second predetermined frictional force.

  As will be described later, the second engagement portion 5B is engaged with the drive member 5D with a slight frictional force that is sufficiently smaller than the first engagement portion 5A and can be ignored. However, the degree of difference between the frictional forces is not limited to that described above. For example, the second engaging portion 5B has the same frictional force as the first engaging portion 5A. The structure may be engaged with the driving member 5D.

  Each engagement portion 5A, 5B (particularly the first engagement portion 5A) is engaged with the drive member 5D as described above, so that the drive member due to expansion and contraction of the piezoelectric element 5C when a voltage is applied. When the moving speed of 5D is low, the holding base 31A moves in the moving direction of the driving member 5D with respect to the frame 31B according to the movement of the driving member 5D. In addition, when the moving speed of the driving member 5D due to expansion and contraction of the piezoelectric element 5C when a voltage is applied is high, the holding base 31A does not move relative to the frame body 31B even if the driving member 5D moves. Yes.

  As will be described in detail later, when the driving member 5D is repeatedly moved in the forward and reverse directions at an appropriate speed, the holding base 31A moves in an appropriate direction, and the objective lenses 2A and 2B are moved in an appropriate direction together with the holding base 31A and the like. The objective lenses 2A and 2B can be switched.

  As already understood, the driving member 5D is provided with two objective lenses 2A and 2B and two sets of lens actuators (lens driving means) 21A and 21B (details will be described later) for correcting and driving the objective lenses 2A and 2B. The holding base 31A is a member that drives the holding base 31A to the use position, and since the cross-sectional shape is square, this has the effect of preventing rotation, and means for preventing rotation of the holding base 31A is unnecessary. It has become.

  Furthermore, since the cross section of the drive member 5D is formed in a square shape, it is not necessary to consider the direction of the drive member 5D when installing the drive member 5D, and the assembly of the apparatus is facilitated. Further, since the drive member 5D has a square cross section, the drive member 5D is reduced in weight with a small amount of material, and the drive member 5D is twisted (centered on the central axis extending in the Y-axis direction, which is the longitudinal direction). The rigidity against twisting) can be improved. The cross section of the drive member 5D may be non-circular, but is most preferably square in this way.

  Here, the track moving means 101, the slide driving means 5 and the like will be described in more detail.

  The housing 3A of the pickup mechanism 3 is formed in a “T” shape in which the width of the portion 105 on the spindle 4 side (length in the Y-axis direction) is wide and the width of the portion 107 on the anti-spindle side is narrow. On both sides in the width direction of the side portion 105, the guide member 109 is engaged and supported, and is movable in the X-axis direction. Then, as described above, the pickup motor 3, the frame 31B, the drive member 5D, the holding base 31A, the objective lenses 2A and 2B, and the like are driven by the thread motor 103 shown in FIG. It has become.

  The frame body 31 </ b> B extends in the Y-axis direction and is provided on the housing 3 </ b> A of the pickup mechanism 3. The frame 31B is provided between the optical disk 6 held by the spindle 4 and the housing 3A of the pickup mechanism 3 in the Z-axis direction, and the housing 31A of the pickup mechanism 3 in the X-axis direction. Of the portion 105 on the spindle 4 side, it is provided near the portion 107 on the anti-spindle side.

  A flange portion 31C for fixing one end portion of the piezoelectric element 5C is provided at one end portion in the longitudinal direction (Y-axis direction) of the frame body 31B. A first guide portion 31E for supporting the drive member 5D so as to be movable in the Y-axis direction is provided near the flange portion 31C, and the drive member is provided at the other end portion in the longitudinal direction of the frame body 31B. A second guide portion 31D is provided for supporting 5D movably in the Y-axis direction. The flange portion 31C and the guide portions 31D and 31E are provided on one straight line in the Y-axis direction, and are provided on the side away from the housing 3A of the pickup mechanism 3 in the Z-axis direction. ing.

  When viewed from the Y-axis direction, each guide portion 31D, 31E is provided with a square through hole. This square through hole is formed to be slightly larger than the square cross section of the drive member 5D. The drive member 5D enters the through holes of the guide portions 31D and 31E, and the drive member 5D. And the guide portions 31D and 31E are engaged with each other with a small frictional force so that the drive member 5D can be easily engaged with the frame 31B only in the longitudinal direction (Y-axis direction) of the drive member 5D. It can be moved.

  Since the piezoelectric element 5C is provided between the flange portion 31C and one end of the drive member 5D, the drive member 5D is relative to the frame body 31B by the amount of expansion / contraction of the piezoelectric element 5C. To move to. The length of the drive member 5D is slightly longer than the distance between the guide portions 31D and 31E of the frame 31B. Even when the piezoelectric element 5C expands and contracts and the driving member 5D moves, the driving member 5D continues to engage with the guide portions 31D and 31E.

  The holding base 31A is provided between the housing 3A of the pickup mechanism 3 and the optical disk 6 held by the spindle 4 in the Z-axis direction, and is provided in a portion 105 on the spindle 4 side of the pickup mechanism 3 in the X-axis direction. It has been. The holding base 31A includes a main body 111 and the engaging portions 5A and 5B. The main body 111 is formed in a plate shape, and the length of the main body 111 (the length in the Y-axis direction) is a predetermined length shorter than the drive member 5D. Each of the engaging portions 5A and 5B is provided integrally with the main body 111 on one end side (the side away from the spindle 4) in the width direction (X-axis direction) of the main body 111.

  As shown in FIG. 2A, the first engagement portion 5A is provided with a square through hole. The size of the through hole 113 of the first engagement portion 5A is formed larger than the square cross section of the drive member 5D, and in the state where the drive member 5D enters the first engagement portion 5A, Two surfaces (two surfaces adjacent to each other orthogonal to each other) 115 and 117 of the through hole 113 of one engagement portion 5A are two surfaces (two surfaces adjacent to each other orthogonal to each other) 115D. 119 and 121 are in contact with each other to make a sliding pair. Further, the other two surfaces (two surfaces adjacent to each other orthogonally) 123 and 125 of the through hole 113 of the first engagement portion 5A are the other two surfaces (the surfaces orthogonal to each other). Two adjacent surfaces) 127 and 129 are opposed to each other with a predetermined distance.

  An elastic body 5E (131) is provided between the surface 123 of the through hole 113 of the first engaging portion 5A and the surface 127 of the driving member 5D facing away from the surface 123. An elastic body 5E (133) is also provided between the surface 125 of the through hole 113 of the first engagement portion 5A and the surface 129 of the driving member 5D facing away from the other surface 125. It has been.

  The surface 119 of the drive member 5D is pressed against the surface 115 of the through hole 113 by the elastic body 5E (131), and the surface 121 of the drive member 5D is pressed against the surface 117 of the through hole 113 by the elastic body 5E (133). In addition, a predetermined amount of frictional force acts between the first engaging portion 5A and the driving member 5D.

  Further, as shown in FIG. 2B, the second engagement portion 5B is provided with a square-shaped through hole 135. The size of the through hole 135 of the second engaging portion 5B is formed to be the same size as the square cross section of the driving member 5D or slightly larger, and is driven into the through hole 135 of the second engaging portion 5B. In the state in which the member 5D is inserted, the four surfaces of the through hole 135 of the second engagement portion 5B and the four surfaces of the drive member are engaged with each other by sliding with a small frictional force. In this way, only a negligible frictional force (fine frictional force) can be exerted between the second engaging portion 5B and the driving member 5D.

  Here, the installation state of the elastic body 5E will be described in detail with reference to FIG.

  First, the installation state of the elastic body 131 provided between one surface 123 of the through hole 113 of the first engaging portion 5A and the surface 127 of the driving member 5D facing away from the surface 123. Will be described. The elastic body 131 is composed of a rectangular thin plate member made of metal such as spring stainless steel.

  When viewed from the Y-axis direction, grooves 137 and 139 are formed through both ends of one surface 123 of the through hole 113 of the first engagement portion 5A so as to penetrate in the Y-axis direction. One end of a thin plate-like elastic body 131 is, for example, press-fitted into one groove 137 of each groove 137, 139, and the thin plate-like elastic body 131 is inserted into the other groove 139 of each groove 137, 139. The other end of the elastic member 131 is inserted, for example, by being press-fitted, and the thin plate-like elastic body 131 is fixed to the first engaging portion 5A so as not to move in the Y-axis direction. The intermediate portion of the thin plate-like elastic body 131 fixed in this way is bent toward the drive member 5D, and the substantially central portion of the thin plate-like elastic body 131 is in contact with the drive member 5D with a predetermined pressure. . Note that the length of the thin plate-like elastic body 131 in the Y-axis direction is substantially equal to the length of the first engaging portion 5A in the Y-axis direction. It fits in the through hole 113 of the engaging portion 5A.

  A thin plate-like elastic body 133 is also formed between the other one surface 125 of the through hole 113 of the first engagement portion 5A and the surface 129 of the driving member 5D facing away from the surface 125. It is provided similarly.

  Since the elastic bodies 131 and 133 are provided in this way, as described above, the first engaging portion 5A is engaged with the drive member 5D with a predetermined frictional force.

  In the state where the engaging portions 5A and 5B are engaged with the driving member 5D and the holding base 31A is supported by the driving member 5D, the engaging portions 5A and 5B are respectively connected to the frame body 31B in the Y-axis direction. It is located inside the guide portions 31D and 31E.

  By the way, as shown in FIG. 1, the main body 111 of the holding base 31A is provided with a first objective lens casing (holder) 141 and a second objective lens casing (holder) 143. Yes. The first objective lens housing 141 is provided with a first objective lens 2A and first lens driving means 21A for correcting and driving the first objective lens 2A. The objective lens casing 143 is provided with a second objective lens 2B and second lens driving means 21B for correcting and driving the second objective lens 2B.

  The first objective lens 2A is a lens for irradiating the optical disc 6 held by the spindle 4 with the laser beam that has passed through the optical path of the pickup mechanism 3, and includes the first objective lens housing 141 and the first objective lens 2A. Along with the lens driving means 21A, the holding base 31A is provided at one end in the Y-axis direction. The second objective lens 2B is also a lens for irradiating the optical disc 6 held by the spindle 4 with the laser beam that has passed through the optical path of the pickup mechanism 3, and the second objective lens housing 143, Along with the second lens driving means 21B, the holding base 31A is provided on the other end side in the Y-axis direction.

  The objective lens housings 141 and 143 are disposed between the main body 111 of the holding base 31A and the optical disc 6 held by the spindle 4 in the Z-axis direction, and each objective lens in the X-axis direction. The lens housings 141 and 143 and the objective lenses 2A and 2B are disposed at substantially the same position in the main body 111 of the holding base 31A.

  The distance between the engaging portions 5A and 5B of the holding base 31A (the distance between the center of the first engaging portion 5A and the center of the second engaging portion 5B in the Y-axis direction) SA is shown in FIG. As shown in (a), the distance between the objective lenses 2A and 2B (the distance between the centers of the objective lenses 2A and 2B in the Y-axis direction) SB is substantially equal to or larger than SB. Further, the distance SA between the engaging portions 5A and 5B of the holding base 31A is the respective objective lenses (centers of the objective lenses) 2A and 2B and the engaging portions (centers of the engaging portions) 5A and 5B of the holding base 31A. Is approximately equal to or greater than the distance SC in the X-axis direction. Instead of the distance SA, the end of the first engagement portion 5A (the end opposite to the second engagement portion 5B) and the end of the second engagement portion 5B (the first portion You may employ | adopt the distance SD between the engaging part 5A and the edge part on the opposite side).

  Further, when the distance SB and the distance SC are greatly different, the distance SA is substantially equal to or larger than the larger distance of the distances SB and SC. It is desirable.

  Further, the drive member 5D moves and the holding base 31A (the objective lenses 2A and 2B) moves in the Y-axis direction. The engagement of the holding base 31A to the guide portions 31D and 31E of the frame body 31B. When the portions 5A and 5B come into contact with each other, the movement stroke of the holding base 31A is regulated.

  That is, as shown in FIG. 3A, in a state where the holding base 31A is located on one side in the Y-axis direction, the engaging portion 5A of the holding base 31A and the guide portion 31E of the frame 31B are connected. The holding bases 31A are in contact with each other, and in this state, the positions of the center of the spindle 4 and the center of the one objective lens 2A substantially coincide with each other. As shown in FIG. 3B, when the holding base 31A is located on the other side in the Y-axis direction, the engaging portion 5B of the holding base 31A and the guide portion 31D of the frame 31B are connected. The holding bases 31A are in contact with each other, and in this state, the center of the spindle 4 and the center of the other objective lens 2B substantially coincide with each other in the Y-axis direction.

  When viewed from the Z-axis direction, the frame body 31B, the holding base 31A, and the like are arranged so as to fit inside the part (part on the spindle 4 side) 25 that constitutes the housing 3A of the pickup mechanism 3. (See FIG. 3).

  Further, the first engagement portion 5A is arranged on one side in the Y-axis direction, and the second engagement portion 5B is arranged on the other side, but the position of the first engagement portion 5A in the Y-axis direction is arranged. And the position of the second engaging portion 5B may be interchanged. Further, for example, second engagement portions (engagement portions with a slight frictional force) 5B are arranged at both ends in the Y-axis direction, and first engagement portions (engagement portions with a predetermined frictional force) 5A at the middle portion. It may be a configuration in which is arranged.

  Here, the lens actuators 21A and 21B will be described.

  As shown in FIG. 9, the lens actuator 21A holds the objective lens 2A on a lens holder 212 fixed in a state that can be minutely displaced by a plurality of wires 211, and a coil (illustrated) provided on a side surface of the lens holder 212. The lens holder 212 is displaced by a force generated by the magnet 213 disposed in opposition to the magnet 213 or a force generated by a magnet (not shown) provided in the lens holder 212 and a coil disposed opposite thereto. The minute position correction is performed.

  The driving direction of the objective lens 2A by the lens actuator 21A is the triaxial direction of the tilt angle direction corresponding to the focus direction of the light of the objective lens 2A, the tracking direction same as the radial direction of the optical disc, and the tilt in the radial direction of the optical disc. . Various proposals have been made for these driving methods, and various driving methods can be applied to this lens actuator. The other lens actuator 21B has the same configuration.

  Next, the control unit of the optical disc apparatus 1 will be described.

  FIG. 8 is a block diagram illustrating a schematic configuration of the control unit of the optical disc apparatus 1.

  In FIG. 8, the laser light emitted from the semiconductor laser 1A is condensed on the optical disc 6 through the objective lens 2A and reflected by the recording groove and the guide groove. This light is incident and collected on the light receiving unit 8 via the half mirror 7. The analog signal processing circuit 9 detects and outputs the tracking error signal TE, the focus error signal FE, and the sum signal PE from the signal photoelectrically converted by the pickup mechanism 3.

  The tracking error signal TE is converted from analog to digital by the analog-to-digital converter 10 </ b> A and taken into the microcomputer 11. Similarly, the focus error signal FE is converted from analog to digital by the analog-to-digital converter 10 </ b> B and taken into the microcomputer 11. Further, the sum signal PE is analog-digital converted by the analog-digital converter 10 </ b> C and is taken into the microcomputer 11.

  A ROM 12 is connected to the microcomputer 11, and programs and fixed data are stored therein. Further, a RAM 13 is connected to the microcomputer 11, and variable values and the like are stored therein.

  A digital-analog converter 14A is connected to the microcomputer 11. Here, data obtained by calculating a tracking control drive signal is output, and the tracking control coil 16 is driven through this drive circuit 15A.

  Further, a digital-analog converter 14B is connected to the microcomputer 11. Here, data obtained by calculating a focus control drive signal is output, and the focus control coil 17 is driven via the drive circuit 15B with this value. Although not shown, the tilt control coil is similarly provided to perform tilt control.

  Note that the pickup mechanism 3 of the present embodiment has two systems of movable parts 18 so as to be compatible with optical discs of two or more types. When an optical disc 6 having a standard different from the standard to which one movable part 21A corresponds is loaded, the microcomputer 11 determines this and uses the other movable part 21B. That is, using an element driving means (not shown), an appropriate voltage is applied to the piezoelectric element 5C so that the piezoelectric element 5C repeatedly expands and contracts, the driving member 5D is appropriately driven (moved), and the holding base 31A is moved. Each objective lens 2A, 2B is positioned in the state shown in FIG. 3 (a) or FIG. 3 (b). In addition, the electrical system can be switched accordingly.

  As shown in FIGS. 1 and 8, the pickup mechanism 3 includes two objective lenses 2A and 2B and two sets of lens actuators (lenses) that respectively perform minute position correction of the objective lenses 2A and 2B. Drive means) 21A and 21B.

  The two objective lenses 2A and 2B are different from, for example, a compatible objective lens for DVD and CD and an objective lens for BD. That is, when information is read from a CD (optical disc), the laser generator 1A and the objective lens 2A are used (see FIG. 3A), and the laser light generated by the laser generator 1A is the objective lens. The CD is irradiated through 2A. Similarly, when reading information from a DVD, one of the two laser generators other than the laser generator 1A and the objective lens 2A are used (see FIG. 3A). In the case of reading information from a Blu-ray disc (BD), the other laser generator out of the two laser generators other than the laser generator 1A and the objective lens 2B are used ( (Refer FIG.3 (b)).

  By the way, in the above configuration, when a driving pulse having a waveform composed of a gradual rising portion E1 and a subsequent rapid falling portion E2 as shown in FIG. 4 is applied to the piezoelectric element 5C, the gradual rising portion E1 of the driving pulse is applied. Then, the piezoelectric element 5C gently (at a slow speed) undergoes an elongation displacement in the thickness direction, and the drive shaft (drive member) 5D is displaced in the direction of the arrow AR1 (see FIG. 1) in the Y-axis direction. For this reason, the holding base 31A of the lens switching drive unit 5 that is frictionally coupled to the drive shaft 5D by a pressure contact spring (elastic body) 5E also moves in the direction of the arrow AR1, so that each objective lens 2A, 2B is moved to the arrow. It can be moved in the direction of AR1.

  At the rapid falling portion E2 of the drive pulse, the piezoelectric element 5C rapidly contracts in the thickness direction (at a high speed), and the drive shaft 5D is also displaced in the axial direction opposite to the arrow AR1 (in the direction of the arrow AR2). To do. At this time, the holding base 31A of the lens switching drive unit 5 pressed against the drive shaft 5D by the press contact spring 5E overcomes the frictional force with the drive shaft 5D by its inertial force and substantially remains at that position. The switching drive unit 5 does not move.

  Note that the term “substantially” used herein refers to the additional movement while causing a slip between the holding base 31A drive shaft 5D of the lens switching drive unit 5 in both the direction of the arrow AR1 and the opposite direction (the direction of the arrow AR2). It also means that it moves and moves in the direction of arrow AR1 as a whole due to the difference in driving time. The type of movement is determined according to the given friction condition.

  By continuously applying the drive pulse having the above waveform to the piezoelectric element 5C, the lens switching drive unit 5 can be continuously moved in the direction indicated by the arrow AR2 until the state shown in FIG.

  When the lens switching drive unit 5 (holding base 31A) is moved in the direction opposite to the arrow AR2 (in the direction of the arrow AR1) to the state shown in FIG. 3B, the rapid rising part and the subsequent gentle rising are performed. This can be achieved by applying a driving pulse having a waveform of a falling portion to the piezoelectric element 5C.

  Here, the relationship between the moving speed of the driving member 5D and the movement of the driven body (holding base 31A) will be described in more detail.

  First, the case where the piezoelectric element 5C extends and the holding base 31A moves in the direction of the arrow AR1 will be described.

  By changing the extension speed of the piezoelectric element 5C, the speed in the direction of the arrow AR1 in the drive member 5D provided integrally with the piezoelectric element 5C changes. Here, the value of the speed of the driving member 5D in the direction of the arrow AR1 is expressed in ascending order of a first predetermined speed (positive value) v1 and a second predetermined speed (positive value) v2. (First predetermined speed v1 <second predetermined speed v2).

  When the speed of the driving member 5D is smaller than the first predetermined speed v1, the static friction force between the driving member 5D and the first engaging portion 5A of the holding base 31A (the holding base with respect to the driving member 5D) Between the driving member 5D and the first engaging portion 5A of the holding base 31A due to the frictional force between the driving member 5D and the first engaging portion 5A when 31A is not relatively moving. The holding base 31 </ b> A moves in the direction of the arrow AR <b> 1 by the same amount as the amount of movement of the drive member 5 </ b> D in the direction of the arrow AR <b> 1 by one extension of the piezoelectric element 5 </ b> C without slipping. .

  When the speed of the driving member 5D is larger than the second predetermined speed v2, a static friction force or a dynamic friction force (relative to the driving member 5D) is generated between the driving member 5D and the first engaging portion 5A of the holding base 31A. Despite the presence of the frictional force between the drive member 5D and the first engaging portion 5A when the holding base 31A is relatively moving, the inertial force due to the mass of the holding base 31A etc. Thus, even if slip occurs between the driving member 5D and the first engaging portion 5A of the holding base 31A and the driving member 5D moves in the direction of the arrow AR1 due to the extension of the piezoelectric element 5C, the holding base 31A does not move. The holding base 31A does not move relative to the frame 31B without moving in the direction of the arrow AR1.

  Friction between the drive member 5D and the first engagement portion 5A of the holding base 31A when the speed of the drive member 5D is equal to or higher than the first predetermined speed v1 and equal to or lower than the second predetermined speed v2. A certain amount of slip occurs between the driving member 5D and the first engaging portion 5A of the holding base 31A due to the force (dynamic friction force or static friction force) and the inertial force due to the mass of the holding base 31A, etc., and the piezoelectric element 5C The holding base 31A is moved in the direction of the arrow AR1 by an amount smaller than the amount of movement of the drive member 5D in the direction of the arrow AR1 by the one-time extension. As the speed of the drive member 5D approaches the second predetermined speed v2, the amount of slip between the drive member 5D and the first engagement portion 5A of the holding base 31A increases, and the drive member 5D The difference between the amount of movement and the amount of movement of the holding base 31A increases.

  The case where the piezoelectric element 5C contracts and the drive member 5D moves in the direction opposite to the direction of the arrow AR1 (the direction of the arrow AR2) is the same as the case where the piezoelectric element 5C extends.

  Then, for example, the voltage applied to the piezoelectric element 5C is appropriately controlled as shown in FIG. 4 to move the driving member 5D in the direction of the arrow AR1 at a speed smaller than the first predetermined speed v1, and thereafter If the operation of moving the driving member 5D in the direction of the arrow AR2 at a speed larger than the second predetermined speed v2 is repeated, the holding base 31A moves in the direction of the arrow AR1.

  Conversely, the drive member 5D is moved in the direction of the arrow AR1 at a speed larger than the second predetermined speed v2, and then the drive member 5D is moved in the direction of the arrow AR2 at a speed smaller than the first predetermined speed v1. If the operation of moving to is repeated, the holding base 31A moves in the direction of the arrow AR2.

  Note that since the frictional force between the second engaging portion 5B of the holding base 31A and the driving member 5D is very small, even if the driving member 5D moves at a speed smaller than the first predetermined speed v1. A slip is generated between the second engagement portion 5B of the holding base 31A and the drive member 5D. However, since the holding base 31A is also engaged with the driving member 5D by the one engaging portion 5A, even when the speed of the driving member 5D is smaller than the first predetermined speed v1, the driving member 5D. The holding base 31 </ b> A moves with the movement.

  When the holding base 31A is moved, the waveform of the voltage applied by the piezoelectric element 5C does not have to be composed of only a straight portion as shown in FIG. Further, instead of or in addition to the speed of the drive member 5D, the acceleration of the drive member may be appropriately controlled to move the holding base 31A.

  By the way, in the optical disc apparatus 1, when the optical disc 6 is inserted into a disc tray (not shown) and detected, the screw shaft 40 is rotationally driven by the control circuit, and the pickup mechanism 3 is moved to the innermost peripheral position of the optical disc 6. To discriminate the disc. At the time of disc discrimination, the lens switching drive unit 5 is driven to move the objective lens 2A or 2B to a predetermined position to select the red laser or blue laser in order to make the best discrimination as the system.

  According to the optical disc apparatus 1, since the holding base 31A is supported by the driving member 5D at the engaging portions 5A and 5B provided apart from each other, the holding base 31A moves relative to the driving member 5D. Even if a moment is generated in the holding base 31A due to the inertial force or the like of the holding base 31A, the generated moment can be accurately received, and yawing (oscillation around the Z axis), pitching (X axis) of the holding base 31A (Rocking around) can be reduced. Furthermore, the rolling (swinging around the Y axis) of the holding base 31A can be reduced, and the holding base 31A moves smoothly with respect to the drive member 5D. Further, the holding base 31A can be positioned in an accurate position and not in a tilted state. Therefore, each objective lens 2A, 2B can be positioned at an accurate position.

  More specifically, if the second engagement portion 5B does not exist, the distance equivalent to the distance SA shown in FIG. 3A becomes small, and the support of the holding base 31A with the driving member 5D becomes unstable. Thus, the moment generated in the holding base 31A due to the inertial force of the holding base 31A when the holding base 31A moves with respect to the drive member 5D causes yawing or pitching in the holding base 31A, and the first engaging portion Although 5A is slightly inclined with respect to the driving member 5D, the frictional force in the first engaging portion 5A is increased, and there is a risk that problems such as the holding base 31A not moving with respect to the driving member 5D may occur. Since the second engaging portion 5B is provided at a position distant from the first engaging portion 5A, the situation of slightly tilting as described above is avoided, and the holding base 31A is supported by the driving member 5D. It is possible to avoid a situation where it becomes unstable.

  Further, according to the optical disc apparatus 1, each engagement portion 5A, 5B is not engaged with the drive member 5D with a predetermined friction force, but the first engagement portion 5A is driven with a predetermined friction force. Since the second engaging portion 5B engages with the member 5D and the driving member 5D is engaged with a slight frictional force, in other words, a force is applied from the driving member 5D only through the first engaging portion 5A. Since the holding base 31A is moved, the holding base 31A can be moved in a stable state.

  More specifically, when the engagement portions 5A and 5B are engaged with the drive member 5D with a predetermined friction force that is not weak, the engagement portions 5A and 5B are always driven with the physically same friction force. If it is engaged with the member 5D, there is no particular problem. However, since the engaging portions 5A and 5B are composed of mechanical parts, the engaging portions 5A and 5B are physically the same. The drive member 5D is not engaged by frictional force, and the frictional force of the engaging portions 5A and 5B is different due to temperature change and long-term use.

  As described above, when the drive member 5D is moved and the holding base 31A is moved in a state where there is a difference between the frictional forces of the engaging portions 5A and 5B, the drive member 5D is moved at the same speed. However, in some cases, the holding base 31A moves through both the engaging portions 5A and 5B, and in some cases, the holding base 31A moves through only one engaging portion 5A. The holding base 31A moves in an unstable state.

  However, in the optical disc apparatus 1, since the force for moving the holding base 31A is received only through the first engaging portion 5A, the above-described problems are avoided and the holding base is stable. 31A can be moved.

  The optical disc apparatus 1 includes a drive member that is movably provided on a base member, an electro-mechanical conversion element that is provided to move the drive member, and a first engagement that engages with the drive member. And a second engagement portion that engages with the drive member apart from the first engagement portion, and is supported by the drive member by being engaged with the engagement portions, with respect to the drive member A movable body that is movable, and a movement amount of the driven body with respect to a movement amount of the driving member by changing a speed at which the driving member moves by the electro-mechanical conversion element. It is an example of the drive device comprised so that may change.

It is the perspective view which showed the structure of the optical pick-up switching mechanism in the optical disk apparatus to which the positioning mechanism using an electro-mechanical conversion element is applied. It is a figure which shows the II-II arrow in FIG. It is a top view explaining the state in which the pickup mechanism is operating. It is a figure which shows an example of the waveform of the drive pulse applied to an electromechanical conversion element. It is sectional drawing which showed the structure of the lens assembly to which the positioning mechanism using the conventional electromechanical conversion element was applied. It is sectional drawing along the VI-VI line of the lens assembly shown in FIG. It is the perspective view which showed the structure of the lens assembly to which the positioning mechanism using the conventional electromechanical conversion element was applied. It is a block diagram explaining the control part of an optical disk device. It is a perspective view explaining the structure of a lens actuator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk apparatus 1A Semiconductor laser generator 2A 1st objective lens 2B 2nd objective lens 3 Pickup mechanism 3A Housing | casing 4 Spindle 6 Optical disk 5A 1st engaging part 5B 2nd engaging part 5C Piezoelectric element 5D Drive member 21A First lens driving means 21B Second lens driving means 31A Holding base 31B Frame 101 Track moving means

Claims (3)

A drive member provided on the base member so as to be movable in a uniaxial direction;
An electro-mechanical conversion element provided on the base member for moving the drive member;
A first engagement portion that engages with the drive member; and a second engagement portion that engages with the drive member apart from the first engagement portion, and is engaged with the engagement portions. A driven body supported by the driving member and thereby movable in the uniaxial direction with respect to the driving member;
And the moving amount of the driven body with respect to the moving amount of the driving member is changed by changing the moving speed when the driving member moves by the electro-mechanical conversion element. A drive device characterized by that. A drive member provided on the base member so that a cross section by a plane perpendicular to the longitudinal direction is formed in a non-circular shape and is movable in the longitudinal direction;
One end of the expansion / contraction direction is provided integrally with the base member so that the expansion / contraction direction is parallel to the longitudinal direction of the drive member, and the other end of the expansion / contraction direction is provided integrally with the drive member. An electro-mechanical transducer;
A first engagement portion that engages with the drive member with a first predetermined friction force, and a second engagement portion that is separated from the first engagement portion and engages with the drive member with a second predetermined friction force. Engaging with each of the engaging portions, and supported by the driving member so as to be movable with respect to the driving member in the longitudinal direction of the driving member, and a voltage is applied. When the moving speed of the driving member due to expansion and contraction of the electro-mechanical conversion element is small, the driving member moves according to the movement of the driving member, and when the moving speed is large, it does not move even when the driving member moves. A driven body that is;
A drive device comprising: A spindle that holds the central portion of the optical disc and rotationally drives the optical disc;
At least one of reading information recorded on the optical disk held by the spindle, recording information on the optical disk, erasing information recorded on the optical disk, and rewriting information recorded on the optical disk A pick-up mechanism provided with a laser generator for generating a laser beam for performing any of the above and an optical path for guiding the generated laser beam to an optical disc;
Track moving means which can move and position the pickup mechanism in a radial direction of the optical disc held by the spindle together with a housing provided with the pickup mechanism;
A frame integrally provided in a casing provided with the pickup mechanism;
A cross section formed by a plane orthogonal to the longitudinal direction is formed in a non-circular shape, and the longitudinal direction intersects the radial direction of the optical disk held by the spindle and the thickness of the optical disk held by the spindle A driving member provided on the frame so as to be movable in the longitudinal direction so as to be in a direction orthogonal to the direction;
One end of the expansion / contraction direction is provided integrally with the frame, and the other end of the expansion / contraction direction is provided integrally with the drive member such that the expansion / contraction direction is parallel to the longitudinal direction of the drive member. An electro-mechanical transducer;
A first engagement portion that engages with the drive member; and a second engagement portion that is separated from the first engagement portion and engages with the drive member. A holding base that is supported by the drive member by moving together and moves in the longitudinal direction of the drive member as the drive member moves;
A first objective that is provided on the holding base and irradiates an optical disc held on the spindle with laser light that has passed through the optical path of the pickup mechanism when the holding base is positioned on one end side in the moving direction. With a lens;
A second laser is provided on the holding base, and irradiates the optical disc held on the spindle with laser light that has passed through the optical path of the pickup mechanism when the holding base is positioned on the other end side in the moving direction. Objective lens;
An optical disc apparatus comprising:

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