Drive device and information recording and processing device

A drive device includes a base and a driven member placed on the base. The driven member is capable of rotation on the base and has a circular surface following the direction of rotation. A roller member contacts the outside or inside of the circular surface of the driven member and is supported to be capable of rotation together with the driven member. A vibration actuator contacts the roller member and drives the roller member to rotate. A pressing member presses the vibration actuator in a direction substantially perpendicular to the axis of rotation of the driven member. The pressing member presses the vibration actuator against the roller member, which in turn is pressed against the driven member.

The disclosures of the following publications and applications are herein 
incorporated by reference: 
(1) 222 Piezoelectric Linear Motors for Application to Driving a Light 
Pick-Up Element, by Tomikawa et al., 5th Symposium on Dynamics Related to 
Electromagnetic Force, Collected Papers, pages 393-398, Jun. 9-11, 1993. 
(2) Japanese Laid-Open Patent Application No. 7-143770. 
(3) U.S. patent application Ser. No. 08/377,466 (which is based on 
JP7-143770). 
BACKGROUND OF THE INVENTION 
1. Field of Invention 
The present invention relates to a drive device for driving a member to 
rotate using a vibration actuator. The present invention also relates to 
an information recording and processing device for performing reading 
and/or writing of information by causing an information recording medium 
to rotate using the drive device. 
2. Description of Related Art 
In the past, when rotatably driving a disk such as a turntable using a 
vibration actuator, a disk shaped vibration actuator that rotated was 
used. 
This vibration actuator is provided at least with a disk (rotor) and an 
elastic member (stator) for driving the disk to rotate. A piezoelectric 
element caused vibration in the elastic member, and a pressing member 
pressed the disk into contact with the elastic member. These constituent 
elements are stacked in sequence in the direction of the axis of rotation 
of the disk. 
However, in this type of structure, because the disk, elastic member, 
piezoelectric element, and pressing member, and the like, are stacked in 
sequence in the direction of the axis of rotation of the disk, the space 
in the direction of the axis of rotation of the disk must be made large. 
Therefore, when the vibration actuator is incorporated into an information 
recording and processing device (e.g., a disk drive), it becomes difficult 
to make the size of this processing device compact in the direction of the 
aforementioned axis of rotation. 
Also, because the disk is pressed in the direction of the axis of rotation 
by the pressing member, its position may change in the direction of 
pressing (i.e., as the pressing member is compressed or expanded in the 
pressing direction). Therefore, there is the possibility that the depth of 
focusing of the head for reading/writing the information by projecting a 
light beam on the surface of the disk may change. 
SUMMARY OF THE INVENTION 
One object of the present invention is to provide a drive device that is 
capable of being made compact in the direction of its thickness. Another 
object of the present invention is to provide an information recording and 
processing device for which stable reading/writing operations are possible 
using the aforementioned drive device. 
In order to achieve the above and other objects, according to one 
embodiment of the present invention, a drive device includes a base and a 
driven member placed on the base. The driven member is capable of rotation 
on the base and has a circular surface following the direction of 
rotation. A roller member contacts the outside or inside of the circular 
surface of the driven member and is supported to be capable of rotation 
together with the driven member. A vibration actuator contacts the roller 
member and drives the roller member to rotate. A pressing member presses 
the vibration actuator in a direction substantially perpendicular to the 
axis of rotation of the driven member. The pressing member presses the 
vibration actuator against the roller member, which in turn is pressed 
against the driven member. 
Preferably, the vibration actuator includes a rectangular flat vibration 
element that generates an elliptical movement in a specified portion of 
the vibration element by causing a longitudinal vibration and a bending 
vibration in the vibration element. The vibration element drives the 
roller member to rotate by the elliptical movement. 
The driven member and the vibration actuator can be disposed on the 
identical plane substantially orthogonal to the axis of rotation of the 
driven member. 
The roller can be mounted such that the axis of rotation of the roller 
member can move in relation to the base. 
The base can be formed in a rectangular flat shape, and the vibration 
actuator can be disposed in a corner of the base. 
The drive device can be used in an information recording and processing 
device for performing reading and/or writing of information against an 
information recording medium. In particular, the driven member can be the 
information recording medium or a turntable on which the information 
recording medium is installed. 
Additionally, a roller support member for supporting the aforementioned 
roller member can be provided. This roller support member can be 
configured with an axis member fixed on the aforementioned base and a main 
body supported on the axis member so as to be capable of rotation centered 
on the axis member. The axis of rotation of the roller support member can 
be supported by the main body. The main body of the supporting member can 
be supported within a surface substantially parallel to the surface 
orthogonal to the axis of rotation of the driven member so as to be 
capable of rotation centered on the axis member. 
The vibration actuator can be a type having a first driving force output 
member and a second driving force output member. In this case, the roller 
member can include a first roller in contact with the first driving force 
output member and a second roller in contact with the second driving force 
output member. Also, the roller support member can include a first roller 
support member and a second roller support member for independently 
supporting the first roller and the second roller, respectively. 
When the vibration actuator has a first driving force output member and a 
second driving force output member, the roller member can include a first 
roller in contact with the first driving force output member and a second 
roller in contact with the second driving force output member. The main 
body of the roller support member can include a first member supported on 
the axis member fixed to the base so as to rotate centered on the axis 
member, a second member supporting the axis of rotation of the first 
roller and the axis of rotation of the second roller, and a linking member 
linking the first member and the second member to be capable of mutual 
rotation. 
In a configuration in which the vibration actuator has a first driving 
force output member and a second driving force output member, and the 
roller member can have a first roller in contact with the first driving 
force output member and a second roller in contact with the second driving 
force output member, a first support member and a second support member 
for supporting the driven member. The first support member can be disposed 
in a position symmetrical to the center of the first roller and the driven 
member, and the second roller can be disposed in a position symmetrical to 
the second roller and the driven member. 
Furthermore, the driven member may be provided with a first part having a 
first diameter and a second part having a second diameter smaller than the 
first diameter, and the roller member can be configured so as to contact 
the driven member at the second part.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
FIG. 1 is a plan view showing a first embodiment of the drive device of the 
present invention. FIG. 2 is a cross-sectional view along A--A of the 
drive device in FIG. 1. FIG. 3 is a perspective view specifically showing 
a configuration of a vibration actuator of the drive device according to 
the first embodiment. 
In the present description, the drive device is explained using as examples 
an information recording and processing device for mounting and driving an 
information recording medium such as a CD (compact disk), MD (mini disk), 
DVD (digital video disk), and LD (laser disk), and reading/writing 
information on that information recording medium. 
Base 1 is a one-piece fixed member, e.g., a part of the case (housing) of 
the information recording and processing device. An axis (or shaft) 2 is 
attached to the base 1. The axis 2 supports a disk 3 so that disk 3 is 
capable of rotation. Disk 3 can be a turntable for mounting an information 
recording medium. 
Axes (or shafts) 4a and 4b also are attached to base 1. A lever 6a is 
attached to axis 4a and is capable of rotation about axis 4a. Also, a 
lever 6b is attached to axis 4b and is capable of rotation about axis 4b. 
A roller 8a is attached by an axis (or shaft) 7a to the other end of lever 
6a and is capable of rotation about axis 7a. Also, a roller 8b is attached 
by an axis (or shaft) 7b to the other end of lever 6b and is capable of 
rotation about axis 7b. By this configuration, lever 6a is capable of 
rotating centered on axis 4a on a surface substantially parallel to the 
surface orthogonal to axis 2. Also, lever 6b is capable of rotating 
centered on axis 4b on a surface substantially parallel to the surface 
orthogonal to axis 2. Therefore, roller 8a is supported centered on axis 
4a so as to be capable of rotating (swinging) in the direction indicated 
by arrow P1. Also, roller 8b is supported centered on axis 4b so as to be 
capable of rotating (swinging) in the direction indicated by arrow P2. 
Roller 8a and disk 3 are in contact with each other on their respective 
sides (outer surfaces). Also, roller 8b and disk 3 are in contact with 
each other on their respective sides (outer surfaces). Also, roller 8a and 
disk 3, and roller 8b and disk 3, are configured so as to rotate 
integrally (i.e., together). Axis 2 and axes 7a and 7b are disposed 
substantially parallel to each other. 
Vibration actuator 100 includes a rectangular flat elastic member 10, a 
piezoelectric element 11, which is an electromechanical conversion 
element, attached (e.g., bonded) to the elastic member 10, sliding members 
12a and 12b attached (e.g., bonded) to the force output portions of 
elastic member 10, and a pressing member (a spring) 13, and the like. The 
vibration actuator is configured such that, when a first drive signal 
having a specified frequency and voltage and a second drive signal having 
a different phase from the first drive signal are applied to piezoelectric 
element 11, a first-order longitudinal vibration, vibrating in the 
lengthwise direction of the elastic member 10, and a fourth-order bending 
vibration are generated in the elastic member 10. In the present 
embodiment, vibration actuator 100 is a so-called ultrasonic motor using 
vibrations in the ultrasonic region. 
Such ultrasonic motors are known and are disclosed, for example, in 
"Longitudinal L1-Bending B4 Mode Flat-Plate Motor," disclosed in "222 
Piezoelectric Linear Motors for Application to Driving a Light Pick-Up 
Element," 5th Symposium on Dynamics Related to Electromagnetic Force, 
Collected Papers, pages 393-398, in Japanese Laid-Open Patent Application 
No. 7-143770, and in U.S. Pat. application Ser. No. 08/377,466 (which is 
based on JP7-143770). 
Vibration actuator 100 includes grooves 10a and 10b on both sides of 
elastic member 10, as shown in FIG. 3. Also, as shown in FIG. 2 (which is 
a cross-sectional view along A--A in FIG. 1) and FIG. 3, a pin 15a 
attached to the flange 1a of base 1 is inserted into groove 10a. Also, a 
pin 15b attached to the flange 1a of base 1 is inserted into groove 10b. 
Accordingly, vibration actuator 100 is supported so as to be capable of 
moving only in the direction of pins 15a and 15b. 
Pressing member 13 is a plate-shaped spring member for pressing vibration 
actuator 100 in the direction of disk 3. This pressing direction is 
established in a direction substantially orthogonal to the axis of 
rotation 2 of disk 3. The pressing member 13 is disposed between vibration 
actuator 100 and the flange 1a of base 1. Also, a contact member 14 is 
attached to pressing member 13. Pressing member 13 is in contact with 
vibration actuator 100 via contact member 14. 
The portions of elastic member 10 where the antinodes of the bending 
vibration generated in elastic member 10 are located function as force 
output members. When a fourth-order bending vibration is generated in 
elastic member 10, the antinodes of the bending vibration are formed in 
six locations including both ends of elastic member 10. In the case of the 
present embodiment, sliding members 12a and 12b are provided in two such 
places where the antinodes are located along the longitudinal direction 
excluding the aforementioned both ends. Sliding member 12a also is 
disposed in the position where elastic member 10 contacts roller 8a. 
Sliding member 12b also is disposed in the position where elastic member 
10 contacts roller 8b. By such placement, when pressing member 13 pushes 
elastic member 10 in the direction of disk 3, sliding member 12a and 
roller 8a come into contact, and sliding member 12b and roller 8b come 
into contact. As a result, roller 8a and disk 3 come into contact, and 
roller 8b and disk 3 also come into contact. 
Vibration actuator 100, roller 8a, and disk 3 are disposed in sequence next 
to each other on the identical plane substantially orthogonal to axis 2 of 
disk 3, as shown in FIG. 2. Roller 8b is not illustrated in FIG. 2, but is 
disposed in the same manner substantially on the identical plane. 
Next, the operation of the drive device according to the first embodiment 
is explained. 
A drive circuit (not illustrated) is connected to piezoelectric element 11 
to apply alternating current voltage to the piezoelectric element 11. The 
drive circuit generates a first alternating current voltage (first drive 
signal) having a specified frequency and voltage and a second alternating 
current voltage (second drive signal) having a frequency and voltage equal 
to the first alternating current voltage and having a different phase. 
When the first alternating current voltage and second alternating current 
voltage are applied, piezoelectric element 11 generates a first-order 
longitudinal vibration and a fourth-order bending vibration in the elastic 
member 10, as described before. As a result, sliding members 12a and 12b 
provided on the force output members of the elastic member 10 move in an 
elliptical path (i.e., perform elliptical movement). 
Because sliding member 12a performs an elliptical movement, roller 8a in 
contact with this sliding member 12a rotates centered on axis 7a. Also, 
because sliding member 12b performs an elliptical movement, roller 8b 
rotates centered on axis 7b. These rollers 8a and 8b rotate in the 
identical direction (for example, in the clockwise direction indicated by 
arrow Q in FIG. 1). At this time, disk 3 in contact with rollers 8a and 8b 
rotates in the reverse direction to rollers 8a and 8b centered on its axis 
2 (for example, in the counterclockwise direction indicated by arrow R in 
FIG. 1). 
The direction of rotation and speed of rotation of disk 3 can be varied by 
changing the phase between the first alternating current voltage and the 
second alternating current voltage applied to piezoelectric element 11, or 
the frequency, or the voltage, or the like. 
According to the first embodiment, disk 3 can be driven to rotate by 
pressing vibration actuator 100 in contact with the side of disk 3 in a 
direction substantially orthogonal to axis 2. Therefore, vibration 
actuator 100, rollers 8a and 8b, and disk 3 can be disposed on the 
identical plane substantially orthogonal to axis 2 of disk 3. By this 
construction, it is possible to make the overall device compact in the 
direction of the axis 2 of disk 3. Also, the driving force generated by 
vibration actuator 100 is propagated efficiently to disk 3 by rollers 8a 
and 8b following the movement of disk 3. 
If, for example, the length of elastic member 10 (refer to FIG. 1) is made 
to be 25 mm, the width of elastic member 10 (refer to FIG. 3) can be about 
5 mm. Also, the length of the flange 1a of base 1 (that is, the width of 
the device) can be made to be about 7-8 mm. 
FIG. 4 is a plan view showing a second embodiment of the drive device of 
the present invention. In each embodiment explained below, the identical 
symbols are assigned to the parts serving the same functions as in the 
first embodiment described before. Accordingly, redundant explanation 
thereof is omitted. 
The second embodiment has a different support mechanism for rollers 8a and 
8b compared with the first embodiment. 
A lever 21 is attached so as to be capable of rotation (swinging) by 
rotatably attaching one of its ends to an axis (shaft) 20 attached to base 
1. Also, an axis (shaft) 24 is attached to the other end of lever 21. A 
lever 22 is attached to axis 24 so as to be capable of rotation relative 
to lever 21 about axis 24. 
Axes (shafts) 23a and 23b are attached to both ends of lever 22. Roller 8a 
is attached to axis 23a so as to be capable of rotation. Roller 8b is 
attached to axis 23b so as to be capable of rotation. 
Also, roller 8a is in contact with sliding member 12a of vibration actuator 
100, and roller 8b is in contact with sliding member 12b of vibration 
actuator 100. Furthermore, rollers 8a and 8b are in contact with the 
(outer) side of disk 3. Disk 3 is configured so as to be driven to rotate 
by vibration actuator 100 in the same manner as in the first embodiment. 
In the second embodiment, axis 2 and axes 23a and 23b are disposed 
substantially parallel to each other. Also, vibration actuator 100, 
rollers 8a and 8b, and disk 3 are disposed on the identical plane 
substantially orthogonal to axis 2 of disk 3, in the same manner as in the 
first embodiment (refer to FIG. 2). 
According to the second embodiment, levers 21 and 22 can be made longer 
compared with levers 6a and 6b in the first embodiment. Therefore, it 
becomes easy for rollers 8a and 8b to follow the movement of disk 3, 
making the operation more stable. 
FIG. 5 is a plan view showing a third embodiment of the drive device of the 
present invention. FIG. 6 is a cross-sectional view along B--B of the 
drive device in FIG. 5. 
The third embodiment uses a cylindrical member 30 instead of the disk 3 of 
the first embodiment. Also, as opposed to the first embodiment in which 
disk 3 is supported by axis 2 disposed in its center, the third embodiment 
differs in that the cylindrical member 30 is supported by two rollers 17a 
and 17b mounted so as to be capable of rotation. Roller 17a is rotatably 
provided on axis (shaft) 16a provided on base 1, and roller 17b is 
provided so as to be capable of rotating on axis (shaft) 16b. These 
rollers 17a and 17b are disposed so as to come in contact with the outer 
perimeter of cylindrical member 30. Also, roller 17a is disposed in a 
position symmetrical to the center of roller 8b and cylindrical member 30. 
Similarly, roller 17b is disposed in a position symmetrical to the center 
of roller 8a and cylindrical member 30. In other words, a line passing 
through the centers of rollers 17a and 8b also passes through the center 
of rotation of cylindrical member 30. The same is true for a line passing 
through the center of rollers 17b and 8a. By such placement, stable 
support and pressing can be performed in relation to cylindrical member 
30. 
According to the third embodiment, member 30 can be supported stably even 
when configured so as to be pressed from the side by vibration actuator 
100. Also, the space in the center part of cylindrical member can be used 
for placing the control circuit, and the like, on base 1. This is an 
advantage in that the freedom of design (layout) is increased. 
Furthermore, because the center part of member 30 is not fixed, that center 
part can be used as a recording area. This design also is an effective 
structure when a disk-shaped information recording medium is used instead 
of the cylindrical member 30. In other words, the third embodiment can 
easily be used to directly drive a recording medium disk in that the disk 
can be substituted for cylindrical member 30. 
FIG. 7 is a plan view showing a fourth embodiment of the drive device of 
the present invention. FIG. 8 is a cross-sectional view along C--C of the 
drive device in FIG. 7. 
The fourth embodiment differs from the first embodiment in that sliding 
members 12a and 12b are not provided on elastic member 10 of vibration 
actuator 100. The fourth embodiment is preferred when disk 3 and elastic 
member 10 are made of metal and rollers 8a and 8b are made of resin, and 
the like. 
FIG. 9 is a plan view showing a fifth embodiment of the drive device of the 
present invention. FIG. 10 is a cross-sectional view along D--D of the 
drive device in FIG. 9. 
In the fifth embodiment, a grooved space S is provided on the inside of 
disk 3, formed in the direction of the perimeter, as shown in FIG. 10. 
Thus, disk 3 is cup-shaped. The drive unit is made compact compared to the 
first embodiment. Other than size, however, the drive unit is the same as 
that of the first embodiment and includes vibration actuator 100, pressing 
member 13, pin 15, rollers 8a and 8b, and levers 6a and 6b, and the like. 
The drive unit is disposed in space S of disk 3. Referring to FIG. 10, 
roller 8a is in contact with a sliding member 12a of vibration actuator 
100 and with a curved surface 3a (i.e., a radially inward facing surface) 
on the inner surface of the outer perimeter of space S of disk 3. In the 
present embodiment, the direction in which pressing member 13 pushes 
vibration actuator 100 is the direction away from the center of disk 3. 
In the fifth embodiment, the driving force generated by vibration actuator 
100 is propagated via rollers 8a and 8b to curved surface 3a on the outer 
perimeter of space S formed in disk 3. Thus, disk 3 is driven to rotate. 
According to the fifth embodiment, because disk 3 is driven from the 
inside, it is possible to make the device compact even in the planar 
direction. This structure is particularly suitable when the diameter of 
the driven disk 3 is large. 
FIG. 11 is a plan view showing a sixth embodiment of the drive device 
according to the present invention. FIG. 6 has the drive unit previously 
described disposed in a corner of base 1 having a rectangular plane 
surface. Accordingly, the dead space created in the rectangular (e.g., 
square) base 1 and disk 3 can be utilized effectively. 
FIG. 12 is a plan view showing a seventh embodiment of the drive device of 
the present invention. In FIG. 12, for the sake of explanation, one part 
of disk 3 is shown in a cut-open state. FIG. 13 is a cross-sectional view 
along E--E of the drive device in FIG. 12. 
In the seventh embodiment, disk 3 is constituted by a first part 3b having 
a large diameter and a second part 3c having a smaller diameter than part 
3b. Also, rollers 8a and 8b are in contact with the outer perimeter of the 
second part 3c. 
In the configuration of the seventh embodiment, when the identical drive 
unit (as the first embodiment) is used and the diameter of the first part 
3b of disk 3 is set to the same size as the diameter of disk 3 of the 
first embodiment, the diameter of rollers 8a and 8b are set larger than in 
the first embodiment. Therefore, the speed of rotation of disk 3 can be 
raised compared with the first embodiment. 
Because rollers 8a and 8b are not effected by the speed of rotation of disk 
3, that speed may be set suitably in the design, considering the space of 
the device, and the like. 
As explained in detail above, according to the present invention, by 
pressing the vibration actuator in contact in a direction substantially 
orthogonal to the axis of the driven member from the side of the driven 
member, the driven member can be driven to rotate. Therefore, the 
vibration actuator, roller member, and driven member can be disposed on 
the identical plane substantially orthogonal to the axis of rotation of 
this driven member, and it becomes possible to make the device compact in 
the direction of the axis of the driven member. 
Also, the present invention is not limited to the embodiments explained 
above. Various modifications and variations are possible. 
For example, in each embodiment, the disk 3 functioned as a turntable. 
However, when the information recording medium is fabricated from a hard 
material, the information recording medium may be directly driven to 
rotate, like the disk 3. In this case, a mechanism for clamping the disk 3 
should be provided that is capable of rotation. 
Also, as long as no logical contradictions are caused, the characteristics 
of each embodiment can be combined with other embodiments. For example, 
other than for the fourth embodiment, the sliding member can be omitted. 
Also, the structure of the drive unit of the second embodiment can be 
applied to the placement of the drive unit of the fourth and fifth 
embodiments. 
The described vibration actuator used a first-order longitudinal vibration 
and a fourth-order bending vibration (L1-B4 type). The invention is not 
limited to this type of actuator. For example, the vibration actuator may 
also be made in a configuration using a sixth-order bending vibration 
(L1-B6 type), or the like. 
Additionally, a piezoelectric member was used as the electromechanical 
conversion element. The invention is not limited to this type of 
electromechanical conversion element. The invention is applicable to other 
devices that convert electrical energy into mechanical displacement. For 
example, an electrostrictive element may be used instead of the 
piezoelectric member. 
While this invention has been described in conjunction with specific 
embodiments thereof, it is evident that many alternatives, modifications 
and variations will be apparent to those skilled in the art. Accordingly, 
the preferred embodiments of the invention set forth herein are intended 
to be illustrative, not limiting. Various changes may be made without 
departing from the spirit and scope of the invention as defined in the 
following claims.