U.S. patent application number 09/945914 was filed with the patent office on 2003-03-06 for focus stop for limiting actuator assembly focus travel.
Invention is credited to Abrahamson, Scott D., Freeman, Robert D., Manes, Joseph P., Rappel, Brian Lee.
Application Number | 20030043726 09/945914 |
Document ID | / |
Family ID | 27542305 |
Filed Date | 2003-03-06 |
United States Patent
Application |
20030043726 |
Kind Code |
A1 |
Freeman, Robert D. ; et
al. |
March 6, 2003 |
Focus stop for limiting actuator assembly focus travel
Abstract
Disclosed is an apparatus such as a disk drive that includes a
base, a first device, and a second device. The first device can
read or write data to a data storage disk. The first device is
movably mounted to the base. For example, the first device can move
in orthogonal first and second planes. The second device is mounted
to the base and is configured to limit movement of the first device
in the second plane. In one embodiment, the first device is
rotatably mounted to the base and includes first and second
portions. The first portion is rotatably mounted to the base, and
the second portion is rotatably connected to the first portion. In
this embodiment, the first portion rotates in the first plane, and
the second portion rotates in the second plane. The second device
is configured to limit rotation of the second portion in the second
plane. Rotation of the second portion is limited when the second
portion engages the second device. Further, the first portion may
be rotatable between first and second positions, and the second
device may limit rotation of the second portion with respect to the
first portion when the first portion is in any position between the
first and second positions.
Inventors: |
Freeman, Robert D.; (Erie,
CO) ; Manes, Joseph P.; (Arvada, CO) ; Rappel,
Brian Lee; (Lyons, CO) ; Abrahamson, Scott D.;
(Longmont, CO) |
Correspondence
Address: |
MR. STEVE VOLK
CHAIRMAN OF THE BOARD
DATAPLAY, INC.
2560 55TH STREET
BOULDER
CO
80301-5706
US
|
Family ID: |
27542305 |
Appl. No.: |
09/945914 |
Filed: |
September 4, 2001 |
Current U.S.
Class: |
720/659 |
Current CPC
Class: |
G11B 7/121 20130101;
G11B 21/22 20130101; G11B 7/0933 20130101; G11B 5/5521 20130101;
G11B 7/0935 20130101; G11B 5/5552 20130101; G11B 25/043 20130101;
Y10T 29/49126 20150115; G11B 7/08576 20130101; G11B 7/0946
20130101; G11B 21/083 20130101; Y10T 29/49009 20150115; G11B 7/093
20130101; G11B 7/22 20130101; Y10T 29/53165 20150115; Y10T 29/49025
20150115; G11B 17/043 20130101 |
Class at
Publication: |
369/244 |
International
Class: |
G11B 017/00; G11B
021/16 |
Claims
What is claimed is:
1. An apparatus comprising: a base; a first device for reading or
writing data to a data storage disk, wherein the first device
comprises a first portion and a second portion, wherein the first
portion is rotatably mounted to the base, and wherein the second
portion is rotatably connected to the first portion; a second
device fixedly mounted to the base, wherein the second device is
configured to limit rotation of the second portion with respect to
the first portion.
2. The apparatus of claim 1 wherein the first portion is rotatable
between first and second angular positions, wherein the second
portion is rotatable with respect to the first portion when the
first portion is in any position between the first and second
angular positions, and wherein the second device is configured to
limit rotation of the second portion with respect to the first
portion when the first portion is in any position between the first
and second angular positions.
3. The apparatus of claim 1 wherein the second device is configured
to engage the second portion to limit rotation of the second
portion with respect to the first portion.
4. The apparatus of claim 1 wherein the first portion is rotatable
between first and second angular positions, wherein the second
portion extends between first and second ends, wherein the second
end of the second portion is positioned between the base and the
second device as the first portion rotates between the first and
second angular positions.
5. The apparatus of claim 4 wherein the first device comprises a
lens mounted to the second portion between the first and second
ends thereof, wherein the lens is configured to transmit light for
reading or writing data to the data storage disk, wherein the
second device is configured to inhibit contact between the lens and
the data storage disk as the second portion rotates with respect to
the first portion.
6. The apparatus of claim 5 wherein the base comprises a surface
which is contained in a first plane, wherein the second device
comprises a rigid plate a bottom surface of which is contained in a
second plane, wherein the first and second planes are parallel to
each other and separated by a predetermined distance.
7. The apparatus of claim 6 wherein the predetermined distance is
calculated as a function of a focal length of the lens
8. The apparatus of claim 7 further comprising the data storage
disk, wherein the data storage disk comprises a surface contained
in a third plane, wherein the third plane is parallel to the first
and second planes, wherein the predetermined distance is calculated
as a function of Ed, where Ed is a distance which the data storage
disk deflects from the third plane as the first device reads or
writes data to the data storage disk.
9. The apparatus of claim 7 wherein the predetermined distance is
calculated as a function of a manufacturing tolerance of the second
portion.
10. The apparatus of claim 7 wherein the predetermined distance is
calculated as a function of a manufacturing tolerance of the
base.
11. The of claim 7 wherein the predetermined distance is calculated
as a function of manufacturing tolerances of components
intermediate to the lens and the data storage disk.
12. The apparatus of claim 1 wherein the second portion is
rotatable between first and second positions, wherein the second
portion engages the second device when the second portion is in the
second position, and wherein the second portion engages the base
when the second portion is in the first position.
13. An apparatus comprising: a base; a first means for reading or
writing data to a data storage disk, wherein the first device
comprises a first portion and a second portion, wherein the first
portion is rotatably mounted to the base, and wherein the second
portion is rotatably connected to the first portion; a second means
mounted to the base, wherein the second means is configured to
limit rotation of the second portion with respect to the first
portion.
14. An apparatus comprising: a base; a first device rotatably
mounted to the base, wherein the first device is configured to
optically read or write data to a data storage disk, wherein the
first device is configured to rotate in first or second orthogonal
planes, wherein the first plane is parallel to a plane that
contains the data storage disk; a second device mounted to the
base, wherein the second device is configured to limit rotation of
the first device in the second plane.
15. The apparatus of claim 14 wherein the second device is
configured to engage the first device to inhibit contact between
the first device and the data storage disk when the first device
rotates in the second plane.
16. The apparatus of claim 14 wherein the base comprises a surface
which is contained in a first plane, wherein the second device
comprises a rigid plate a bottom surface of which is contained in a
second plane, wherein the first and second planes are parallel to
each other and separated by a predetermined distance.
17. The apparatus of claim 14 wherein the second device is
configured to limit rotation of the first device in the second
plane when the first device is in any angular position within the
first plane.
18. An apparatus comprising: a base; a first device movably mounted
to the base, wherein the first device is configured to optically
read or write data to a data storage disk, wherein the first device
is configured to move in orthogonal first and second planes; a
second device mounted to the base, wherein the second device is
configured to limit movement of the first device in the second
plane.
19. The apparatus of claim 18 wherein the second device is
configured to limit movement of the first device in the second
plane when the first device is in any position within the first
plane.
20. The apparatus of claim 18 wherein the base comprises a surface
which is contained in a first plane, wherein the second device
comprises a rigid plate a bottom surface of which is contained in a
second plane, wherein the first and second planes are parallel to
each other and separated by a predetermined distance.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is related to application Ser. No.
09/854,333, filed May 11, 2001 entitled Optical Data Storage with
Enhanced Contrast, application Ser. No.______ filed Sep. 4, 2001,
entitled Cartridge Load/Eject Mechanism for Data Storage Disk
System (Atty Docket No. M-11682 US); application Ser. No.______
filed Sep. 4, 2001, entitled Focus Motor and Mechanism for Optical
Disk Drive, (Atty. Docket No. M-11128 US); Application No.
60/265,830, filed Jan. 31, 2001, entitled Cartridge Loading
Mechanism for Data Storage Disk (Attorney Docket No. M-9847-V1 US);
and application Ser. No. 09/846,042, filed May 1, 2001, entitled
Optical Pickup Unit Assembly Process all of which are incorporated
herein in their entirety (Attorney Docket No. M-9848 US).
BACKGROUND OF THE INVENTION
[0002] Data storage/retrieval devices such as disk drives are well
known in the industry. Disk drives store or retrieve digital data
on a plurality of circular, concentric data tracks on the surfaces
of a rigid data storage disk. The disk is typically mounted for
rotation on the hub of a spindle motor. In disk drives of the
current generation, the spindle motor can rotate the disk at speeds
of up to 10,000 RPM.
[0003] Data is stored to or retrieved from the disk by an actuator
that is controllably moved. The actuator typically includes of an
electromagnetic transducer head carried on an actuator assembly.
The actuator assembly moves the head from track to track and has
assumed many forms historically, with most disk drives of the
current generation incorporating an actuator assembly of the type
referred to as a rotary voice coil actuator assembly. A typical
rotary voice coil actuator assembly includes of a pivot pin fixedly
attached to a disk drive base member. The pivot pin is mounted such
that its central axis is normal to the plane of rotation of the
disk. An actuator assembly frame can be mounted to the pivot pin by
an arrangement of precision ball bearing assemblies, and supports a
coil which is suspended in the magnetic field of an array of
permanent magnets, which are fixedly mounted to the drive base
member. When controlled DC current is applied to the coil, a
magnetic field is formed surrounding the coil that interacts with
the magnetic field of the permanent magnets to rotate the actuator
assembly in accordance with the well-known Lorentz
relationship.
[0004] As the actuator assembly rotates about the pivot pin, the
head is moved across the data tracks along an arcuate path. While
the head is moved across the data tracks, the head may also move in
a vertical direction to bring it closer to the data storage disk.
However, movement in the vertical direction should be limited to
prevent contact between the head and the data storage disk.
SUMMARY OF THE INVENTION
[0005] Disclosed is an apparatus such as a disk drive that includes
a base, a first device, and a second device. The first device can
read or write data to a data storage disk. The first device is
movably mounted to the base. For example, the first device can move
in orthogonal first and second planes. The second device is mounted
to the base and is configured to limit movement of the first device
in the second plane.
[0006] In one embodiment, the first device is rotatably mounted to
the base and includes first and second portions. The first portion
is rotatably mounted to the base, and the second portion is
rotatably connected to the first portion. In this embodiment, the
first portion rotates in the first plane, and the second portion
rotates in the second plane. The second device is configured to
limit rotation of the second portion in the second plane. Rotation
of the second portion is limited when the second portion engages
the second device. Further, the first portion may be rotatable
between first and second positions, and the second device may limit
rotation of the second portion with respect to the first portion
when the first portion is in any position between the first and
second positions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The present invention may be better understood, and its
numerous objects, features and advantages made apparent to those
skilled in the art by referencing the accompanying drawings. The
use of the same reference number throughout the figures designates
a like or similar element.
[0008] FIG. 1 is a perspective view of an exemplary data cartridge
and an exemplary data storage/retrieval system employing the
present invention;
[0009] FIG. 2 is a perspective view of the system shown in FIG. 1
with its cover removed to expose several exemplary components;
[0010] FIGS. 3a and 3b show perspective and top views,
respectively, of the system of FIG. 2;
[0011] FIG. 4 is a perspective view of the cartridge shown in FIGS.
1 and 3;
[0012] FIG. 5a is a top view of the cartridge shown in FIG. 4;
[0013] FIG. 5b is a cross-sectional view of the cartridge shown in
FIG. 5a taken along line AA thereof;
[0014] FIG. 6 is a cross-sectional view of the system of FIG. 3b
taken along line BB thereof;
[0015] FIG. 7a is a perspective view of the system shown in FIG. 2
with several components removed to illustrate several exemplary
components;
[0016] FIGS. 7b-7d are top views of the system shown in FIG.
7a;
[0017] FIG. 8a is a perspective view of an actuator assembly shown
in FIGS. 7a-7d;
[0018] FIG. 8b illustrates operational aspects of the actuator
assembly shown in FIG. 8a;
[0019] FIGS. 9a and 9b show top and side views, respectively, of a
frame of the actuator assembly shown in FIG. 8a;
[0020] FIG. 10a illustrates a perspective view of the upper focus
stop shown in FIGS. 7a-7d;
[0021] FIG. 10b illustrates operational aspects of the upper focus
stop shown in FIG. 10a;
[0022] FIG. 11a is a top view of a parking arm shown in FIGS.
7a-7d;
[0023] FIG. 11b is a bottom, perspective view of the parking arm
shown in FIGS. 7a-7d;
[0024] FIG. 11c is a top, perspective view of the parking arm shown
in FIGS. 7a-7d;
[0025] FIG. 11d is a cross-sectional view of the parking arm shown
in FIG. 11a taken along line CC thereof;
[0026] FIG. 12 is a perspective of the system shown in FIG. 7a with
several components removed to illustrate additional exemplary
components;
[0027] FIG. 13 shows a perspective view of a parking coil and steel
plate shown in FIG. 12;
[0028] FIGS. 14a-14e show isolated cross-sectional views of the
parking arm, parking coil and steel plate of FIGS. 11a-13;
[0029] FIG. 14f illustrates operational aspects of creating Lorentz
forces within the parking coil of FIGS. 14a-14e;
[0030] FIG. 15 is a cross-sectional view of system 100 shown in
FIG. 7c taken along line DD thereof, and;
[0031] FIG. 16a is a top view of a tool used to mount the spindle
motor to the base;
[0032] FIG. 16b is a cross-sectional view of the tool shown in FIG.
16a taken along line EE thereof;
[0033] FIG. 16c illustrates an exploded view of the base, motor and
the tool of FIG. 16a;
[0034] FIG. 16d is a top view of the tool and base shown in FIG.
16b, and;
[0035] FIG. 16e is a cross-sectional view of the tool and base
shown in FIG. 16 taken along line EE thereof.
[0036] While the invention is susceptible to various modifications
and alternative forms, specific embodiments thereof are shown by
way of example in the drawings and will herein be described in
detail. However, the drawings and detailed description thereto are
not intended to limit the invention to the particular form
disclosed. On the contrary, the intention is to cover all
modifications, equivalents, and alternatives falling within the
spirit and scope of the present invention as defined by the
appended claims.
DETAILED DESCRIPTION
[0037] FIG. 1 is a perspective view of an exemplary data
storage/retrieval system 100 and an exemplary data cartridge 102.
Data storage/retrieval systems are often referred to in the art as
disk drives. This description will hereinafter refer to data
storage/retrieval system 100 as "system 100." System 100 is
configured to receive and read/write data to data cartridge
102.
[0038] System 100 includes a base 104 to which all other system 100
components are directly or indirectly connected or mounted, a cover
106, and a door 110 which, together, isolate delicate internal
components from external contaminants. Door 110 is rotatable at its
base between open and closed positions to allow manual loading or
unloading of a data cartridge 102 into or out of system 100.
[0039] System 100 may take form in various sizes. In one
embodiment, the height of system 100 measured in the z direction
may be as small as 10 mm, the width of system 100 measured in the x
direction may be as small as 50 mm, and the length of system 100
measured in the y direction may be as small as 45 mm. Smaller sizes
of system 100 are limited only by the ability to manufacture
smaller components thereof.
[0040] FIG. 2 is a perspective view of the system 100 shown in FIG.
1 with cover 106 removed to expose several exemplary components.
The figures of this detailed description use like reference
numerals to designate like components. With reference to FIG. 2,
exemplary internal components of system 100 include a tray 112 into
which data cartridge 102 (not shown in FIG. 2) is received, a door
spring 114 for biasing door 110 in the closed position, and a
spindle motor 116 (partially shown).
[0041] FIGS. 3a and 3b show perspective and top views of the system
100 of FIG. 2 with data cartridge 102 received in tray 112. FIG. 4
is a perspective view of data cartridge 102 shown in FIGS. 1 and 3.
Data cartridge 102 includes a cartridge shell 120, a top sliding
shutter 122, and a bottom sliding shutter 124. The top and bottom
sliding shutters 122 and 124 are capable of independently sliding
between open and closed states. In FIG. 4, shutter 122 is shown
closed.
[0042] FIG. 5a is a top view of data cartridge 102 shown in FIG. 4
with shutter 122 in the opened state to expose data storage disk
126. With shutter 122 open, spindle motor 116 (FIG. 2) can rotate
disk 126 while data is written thereto or read therefrom. FIG. 5b
is a cross-sectional view of the data cartridge 102 shown in FIG.
5a taken along line AA thereof. As seen in FIG. 5b, data storage
disk 126 is capable of free rotation within cartridge shell
120.
[0043] For purposes of explanation only, the present invention will
be described with reference to system 100 that optically
reads/writes data to the data storage disk 126 in data cartridge
102, it being understood that the present invention may find
application in other types of data storage/retrieval systems
including those that magnetically or electro-magnetically
read/write data to the disk in data cartridge 102. Data storage
disk 126 in data cartridge 102 may take form in the optical data
storage disk described in application Ser. No. 09/854,333 filed May
11, 2001, entitled Optical Data Storage With Enhanced Contrast.
[0044] FIG. 6 is a cross-sectional view of the data system 100 of
FIG. 3b taken along line BB thereof In FIG. 6, data cartridge 102
is shown in a fully loaded position with data storage disk 126
engaging cylinder 130 of spindle motor 116. Application Ser.
No.______, filed Sep. 4, 2001, entitled Cartridge Load/Eject
Mechanism for Data Storage Disk System (Atty Docket No. M-11682
US), and Provisional Application No. 60/265830, filed Jan. 31,
2001, entitled Cartridge-Loading Mechanism For Data Storage Disk,
illustrate operational aspects of loading data cartridge 102 into
system 100. In this position, cylinder 130 can rotate data storage
disk 126 freely within cartridge shell 120 while data is written to
or read from data storage disk 126. Disk 126 includes on its
surfaces a plurality of circular, concentric data tracks or a
single spiral data track which data may be written to or read from
via a light beam (not shown in FIG. 6) incident thereon.
Hereinafter, unless indicated otherwise, disk 126 will be described
as having a plurality of circular, concentric data tracks, it being
understood that disk 126 should not be limited thereto.
[0045] FIG. 7a is a perspective view of system 100 shown in FIG. 2
with several components, such as tray 112, removed. FIGS. 7b-7d are
top views of system 100 shown in FIG. 7a. FIGS. 7a-7d illustrate
several components of system 100. More particularly, FIGS. 7a and
7b illustrate exemplary embodiments of spindle motor 116, z-datums
132a-132d, actuator assembly 134, parking arm 136, and upper focus
stop 140. Although data cartridge 102 is not shown in FIGS. 7a and
7b, spindle motor 116, z-datums 132a-132d, actuator assembly 134,
parking arm 136, and upper focus stop 140 are normally positioned
beneath data storage disk 126 of data cartridge 102 when data
cartridge 102 is fully loaded in system 100.
[0046] With continued reference to FIGS. 7a and 7b, actuator
assembly 134 is one embodiment of a device for reading or writing
data to data storage disk 126. Actuator assembly 134 is rotatably
mounted to base 104 via bearing assembly 138 and actuator assembly
pivot pin 142. As will be more fully described below, a rotation
motor is provided to rotate actuator assembly 134 about actuator
assembly pivot pin 142 in the positive or negative .theta.
directions. Actuator assembly 134 includes a frame 144 (FIGS. 9a
and 9b) which in turn includes a focus arm 146 rotatably connected
to a tracking arm 150. As will be more fully described below, a
focus motor is provided to rotate focus arm 146 about axis 152 in
the positive or negative .beta. directions. It is noted that
positive and negative .beta. directions are perpendicular to sheet
on which FIG. 7b is drawn.
[0047] Actuator assembly 134 further includes a head assembly or
optical pick-up unit (OPU) 154 mounted to focus arm 146. OPU 154
performs a variety of functions one of which is to illuminate data
storage disk 126 with a focused beam of light for reading or
writing data. The focus motor functions to rotate focus arm 146
about rotational axis line 152 to bring a lens 156 of OPU 154 into
focus with a surface (not shown in FIGS. 7a and 7b) of data storage
disk 126. The figures and detailed description illustrate a system
100 having one actuator assembly 134. System 100 may include a
second actuator assembly, possibly mounted to a second base, such
that disk 126 is positioned between two actuator assemblies. In
this embodiment, shutters 122 and 124 (FIGS. 4 and 5b) may be
simultaneously open when cartridge 102 is loaded so that the two
actuator assemblies can simultaneously read or write data.
[0048] Parking arm 136 is one embodiment of a device for
selectively inhibiting movement of actuator assembly 134. Parking
arm 136 is rotatably mounted to base 104 via parking pivot pin 160.
Parking arm 136 is rotatable about pin 160 between parked and
unparked positions. FIGS. 7a and 7b show parking arm 136 in the
parked position. As will be more fully explained below, when
parking arm 136 is in the parked position, it "parks" or engages
actuator assembly 134 to inhibit further movement thereof. FIG. 7c
shows parking arm 136 in the unparked position. With parking arm
136 in the unparked position, actuator assembly 134 is "unparked"
or free to move. Parking arm 136 is capable of parking actuator
assembly 134 at any position in its range of rotation about
actuator assembly pivot pin 142.
[0049] Upper focus stop 140 is one embodiment of a device for
limiting movement of actuator assembly 134 in the positive .beta.
direction. Upper focus stop 140 is fixedly mounted to base 104. As
noted above, focus arm 146 (and thus OPU 154) rotates in the
positive or negative .beta. directions about axis line 152 to bring
lens 156 into focus with the surface of data storage disk 126.
However, rotation of focus arm 146 should be limited to prevent
contact between lens 156 and data storage disk 126. As will be more
fully described below, upper focus stop 140 operates to prevent
contact between lens 156 and data storage disk 126. Upper focus
stop 140 is capable of limiting positive .beta. rotation of focus
arm 146 of actuator assembly 134 at any position in actuator
assembly's range of rotation about actuator assembly pivot pin
142.
[0050] With continued reference to FIGS. 7a and 7b, FIGS. 8a and 8b
show perspective and front views, respectively, of actuator
assembly 134. Actuator assembly 134 includes OPU 154, frame 144,
actuator assembly pivot pin 142, a tracking wire coil 170, and a
focus wire coil 172. Coils 170 and 172 are components of separate
electromagnets. As noted above, actuator assembly 134 is rotatably
mounted on base 104 via actuator assembly pivot pin 142, and frame
144 includes focus arm 146 rotatably attached to tracking arm 150.
In one embodiment, focus arm 146 is rotatably connected to tracking
arm 150 via flex plate 174. Alternative embodiments for rotatably
connecting focus arm 146 to tracking arm 150 are contemplated.
[0051] With continued reference to FIGS. 8a and 8b, FIGS. 9a and 9b
show top and side views, respectively, of frame 144. In one
embodiment, focus arm 146 is formed from carbon fiber layers
176a-176e connected together using an adhesive. Similarly, tracking
arm 150, in one embodiment, is formed from carbon fiber layers
180a-180e connected together using an adhesive. When aligned and
adhered together, carbon fiber layers 180a-180e form an aperture
182 for receiving actuator assembly pivot pin 142 (not shown in
FIGS. 9a and 9b). Further, when aligned and adhered together,
carbon fiber layers 180a-180e form a pair of tracking coil arms
184a and 184b that receive tracking coil 170. Carbon fiber layers
176a-176e when aligned and adhered together form a recess 186 for
receiving the OPU 154. In one embodiment, each of the carbon fiber
layers 176a and 176b includes an extension 190a and 190b,
respectively. As will be more fully described below, extension 190b
interacts with upper focus stop 140 to limit rotation of focus arm
146 in the positive direction, and extension 190a interacts with a
surface on base 104 to limit rotation of focus arm 146 in the
negative .beta. direction. Further, as will be described below,
when parking arm 136 "parks" actuator assembly 134, extension 190b
interacts with the parking arm 136 while extension 190a interacts
with the surface on base 104.
[0052] Frame 144 should not be limited to that shown in the figures
of this detailed description; alternative assemblies are
contemplated. For example, frame 144 may take form in an integrally
formed focus arm 146 rotatably connected to an integrally formed
tracking arm 150. Moreover, extension 190a or 190b could be
separately formed and attached to focus arm 146 rather than
integrally formed with carbon fiber layers 176a and 176b,
respectively.
[0053] With continued reference to FIGS. 9a and 9b, focus arm 146
is rotatably connected to tracking arm 150 via flex plate 174. In
one embodiment, flex plate 174 is formed from a sheet of metal such
as stainless steel. This sheet of metal may be crimped to form
front and back portions 192a and 192b, respectively, rotatably
connected together via a crimped portion 194. Front portion 192a
and back portion 192b are connected to focus arm 146 and tracking
arm 150, respectively. Flex plate 174 functions like a hinge. Flex
plate 174 allows front and back portions 192a and 192b, and thus
focus arm 146, to rotate about axis 152. The narrowest portion of
crimped portion 194 defines axis line 152 about which focus arm 146
rotates. In one embodiment, front portion 192a is fixedly attached
between carbon fiber layers 176b and 176d using an adhesive, and
back portion 192b is fixedly attached between carbon fiber layers
180b and 180d using an adhesive.
[0054] With continued reference to FIGS. 7a, 7b, 8a, and 8b, the
mechanical force for rotating focus arm 146 about axis line 152 is
provided by the focus motor mentioned above. Application Ser.
No.______ filed Sep. 4, 2001, entitled Fringing Field Focus Motor
And Mechanism for Optical Disk Drive (Attorney Docket No. M-11128
US) describes one embodiment of a focus motor. In the embodiment
shown, the focus motor includes focus coil 172 mounted to actuator
assembly 134 and an array of permanent focus magnets 200a-200c
attached to base 104. A variably controlled electrical current is
provided to focus coil 172 via flex circuit 202 (FIGS. 7a and 7b).
The variably controlled electrical current is provided to flex
circuit 202 by system electronics (not shown) mounted on a printed
circuit board (PCB) which, in turn, is attached to the underside of
base 104. The variably controlled current flowing through focus
coil 172 creates a variably controlled magnetic field that
interacts with the permanent magnetic field created by the array of
permanent focus magnets 200a-200c (FIGS. 7a and 7b). The
interaction of these magnetic fields causes focus arm 146 to
controllably rotate about axis line 152 in the positive or negative
.beta. direction depending on the polarity and/or magnitude of the
current provided to focus coil 172. Through the interaction of the
permanent and variably controlled magnetic fields, the distance D
(FIG. 8b) between OPU 154 and the data storage disk 126 positioned
above OPU 154, can be adjusted to bring lens 156 of OPU 154 into
focus with surface 204 of data storage disk 126. With reference to
FIGS. 8a and 8b, OPU 154 includes a lens 156, a light generation
device (not shown) and one or more light detectors (not shown). One
embodiment of OPU 154 is described in application Ser. No.
09/846,042, filed May 1, 2001, entitled Optical Pickup Unit
Assembly Process. The light generation device may take form in a
light emitting diode that generates a light beam 206 (FIG. 8b) for
reading or writing data to data storage disk 126 as data storage
disk 126 is rotated by spindle motor 116 (not shown in FIGS. 8a and
8b). When writing data to data storage disk 126, the intensity of
light beam 206 is modulated by the light generation device in
accordance with data to be written. When reading data from data
storage disk 126, the intensity of light beam 206 is substantially
constant.
[0055] The one or more light detectors detect light reflected from
data storage disk 126 and generate corresponding electrical signals
in response thereto. The magnitude of the electrical signals
generated by the one or more detectors is generally proportional to
the intensity of light reflected from data storage disk 126. With
reference to FIG. 8b, lens 156 focuses the light beam 206 onto data
storage disk 126. Light reflected by the data storage disk 126 also
passes through lens 156 before being detected by the one or more
light detectors of OPU 154.
[0056] FIG. 8b shows that lens 156 is separated from disk surface
204 by distance D. Ideally D should substantially equal focal
length L of lens 156. With D substantially equal to L, lens 156 is
in focus with surface 204 and OPU 154 can properly read or write
data to data storage disk 126. Due to dynamic factors such as
physical irregularities in surface 204 (the physical irregularities
are dynamic in the sense that they cause the surface 204, as seen
by lens 156, to deviate while data storage disk 126 rotates),
improper angular alignment between actuator assembly pivot pin 142
and base 104 more fully described below, or unexpected mechanical
forces applied to either actuator assembly 134 or data storage disk
126, D may vary from L and take lens 156 out of focus with surface
204. Fortunately, if D varies from L, the variances can be detected
in signals generated by the one or more detectors of OPU 154.
[0057] Signals generated by the one or more detectors of OPU 154
are transmitted to system electronics attached to the PCB via flex
circuit 202 (FIGS. 7a and 7b) where they are monitored, for
example, during data read/write operations. The magnitude of these
signals will increase or decrease as D varies with respect to L.
The system electronics compare the generated signals with a
predetermined signal S. The magnitude of S is calculated as a
function of L. If the generated signals compare equally or
substantially equal to S, then distance D should equal or
substantially equal L, and lens 156 is in focus or substantially in
focus with surface 204. If the magnitude of the generated signals
is greater or less than S, then lens 156 is substantially out of
focus with surface 204. In the latter situation, the system
electronics can adjust the magnitude and/or polarity of current
provided to focus coil 172, which in turn causes the focus arm 146,
and thus lens 156 of OPU 154, to rotate about axis 152 until the
magnitude of the generated signals equals or substantially equals
S. With the magnitude of the generated signals equal to S, lens 156
should again be in focus with surface 204.
[0058] Actuator assembly 134 is rotatably mounted to base 104 via
actuator assembly pivot pin 142 (FIGS. 7a. 7b, and 8b). Ideally,
pivot pin 142 should be mounted to base 104 with an angle
therebetween that aligns actuator assembly 134 to disk 126.
Actuator assembly 134 is aligned to disk 126 when a constant
distance separates tracking arm 150 and disk 126 as actuator
assembly 134 rotates about pin 142. Actuator assembly 134 is also
said to be aligned to disk 126 when a constant distance separates
focus arm 146 and disk 126 as actuator assembly 134 rotates about
pin 142. Thus, if the distance D between lens 156 and data storage
disk 126 is constant or substantially constant (e.g., distance D is
equal to or substantially equal to L, the focal length of lens 156)
as actuator assembly 134 rotates through its full range of motion
about pin 142, then actuator assembly 134 is properly aligned with
disk 126. This latter definition of actuator assembly 134 to disk
126 alignment assumes that the angular position of focus arm 146
relative to tracking arm 150 remains constant while actuator
assembly 134 rotates. It is noted that with no current or a
constant current provided to focus coil 172, the angular position
of focus arm 146 relative to tracking arm 150 should remain
constant during rotational movement of actuator assembly 134 about
pivot pin 142.
[0059] If the angular position of pivot pin 142 relative to base
104 is improper, actuator assembly 134 and disk 126 will be
misaligned and, assuming no relative motion between focus arm 146
and tracking arm 150, the distance D between lens 156 and data
storage disk 126 will vary as actuator assembly 134 rotates about
pin 142. System 100 can properly operate notwithstanding
misalignment of actuator assembly 134 and disk 126. More
particularly, when distance D varies from L, as noted above, the
system electronics can adjust the magnitude and/or polarity of
current provided to focus coil 172, which in turn causes the focus
arm 146 to rotate about axis 152 until distance D equals L. In this
fashion, a misalignment between actuator assembly 134 and disk 126
can be corrected. However, this correction requires power
consumption by focus coil 172. Power consumption by system 100 is
sought to be limited particularly when a battery provides the
power.
[0060] Before pivot pin 142 is fixedly mounted to base 104, the
angular position of pivot pin 142 relative to base 104 can be
checked. For example, with data cartridge 102 loaded and cylinder
130 engaging data storage disk 126, current to focus coil 172 can
be externally monitored as actuator assembly 134 travels through
its full range of motion in the positive and negative .theta.
directions. If an improper angular position exists between pivot
pin 142 and base 104, current to focus coil 172 will vary in
essentially a linear manner as actuator assembly 134 travels
through its full range of motion. In the latter situation, the
angular position between pivot pin 142 and base 104 can be adjusted
until the monitored current provided to focus coil is constant as
actuator assembly 134 travels through its full range of motion.
[0061] Ideally, for power conversation reasons, focus coil 172
should draw no current as actuator assembly 134 travels through its
full range of motion. If a non-zero constant current is provided to
focus coil 172 as actuator assembly 134 travels through its full
range of motion, the distance measured in the z-direction between
the actuator and base 104 can be adjusted accordingly. For example,
actuator assembly 134 can be moved up or down on pivot pin 142
until no current is provided to focus coil 172. Alternatively, the
angle between pivot pin 142 and base 104 can be further adjusted
until no current is provided to focus coil 172. This latter angular
adjustment should occur in a direction which is orthogonal to the
angular adjustment direction which resulted in a constant current
provided to focus coil 172 as actuator assembly travels through is
full range of motion in the .theta. direction.
[0062] The angular position between pivot pin 142 and base 104 may
also be checked by monitoring the signals generated by OPU 154 as
actuator assembly 134 travels through its full range of motion.
This method presumes that the focus motor is turned off (i.e., no
current or a constant current is provided to focus coil 172). For
example, with data cartridge 102 loaded and cylinder 130 engaging
data storage disk 126, OPU 154 generates signals in response to
receiving light reflected from data storage disk 126 as actuator
assembly 134 rotates through its full range of motion. If a proper
angular position exists between pivot pin 142 and base 104, then
the magnitude of the signals generated by OPU 154 will be constant
as actuator assembly 134 travels through its full range of motion.
If, however, an improper angular position exists between pivot pin
142 and base 104, the magnitude of the generated signals will vary
approximately linearly as actuator assembly 134 travels through its
full range of motion. In the latter situation, the angular position
of pivot pin 142 relative to base 104 can be adjusted until the
magnitude of the generated signals is constant as actuator assembly
134 travels through its full range of motion. With a proper angle
between base 104 and pivot pin 142, actuator assembly 134 will be
properly aligned with data storage disk 126, and pivot pin 142 can
be fixedly attached to base 104. In one embodiment, the pivot pin
142 can be fixedly attached to base 104 by adhesive bonding with an
ultraviolet (UV) light sensitive adhesive such as EMCAST 612.
[0063] Focus coil 172 functions to rotate focus arm 146 and keep
lens 156 in focus with data storage disk 126. However, rotation of
focus arm 146 and thus lens 156 must be limited to prevent contact
between lens 156 and data storage disk 126. If contact occurs
between lens 156 and data storage disk 126 while data storage disk
126 is rotating, damage may result. Upper focus stop 140 functions
to prevent contact between lens 156 and data storage disk 126. With
continued reference to FIGS. 7a and 7b, FIG. 10a illustrates a
perspective view of one embodiment of upper focus stop 140 having
oppositely facing top and bottom surfaces. Upper focus stop 140
constitutes a rigid plate fixedly mounted to base 104 via fasteners
210a and 210b.
[0064] With upper focus stop 140 mounted to base 104, a gap is
created between upper focus stop 140 and surface (lower focus stop)
212 of base 104 that allows limited rotation of focus arm 146 in
the positive or negative .beta. directions. FIG. 10b illustrates a
side view of actuator assembly 134 with extensions 190a and 190b
positioned in gap G between upper focus stop 140 and base 104.
Upper focus stop 140 is positioned to limit the rotation of focus
arm 146 in the positive .beta. direction. More particularly, before
lens 156 can contact data storage disk 126, extension 190b of focus
arm 146 engages the bottom surface of upper focus stop 140. Once
extension 190b and upper focus stop 140 engage each other, focus
arm 146, and thus lens 156, can no longer rotate in the positive
.beta. direction. Lower focus stop 212 is defined as a surface of
base 104 that limits the negative rotation of focus arm 146. Once
extension 190a and lower focus stop 212 engage each other, focus
arm 146 can no longer rotate in the negative .beta. direction.
[0065] With no forces applied to actuator assembly 134, distance A
(FIG. 10b) separates extension 190b from upper focus stop 140 and
distance B separates extension 190a from lower focus stop 212. As
mentioned above, dynamic factors such as mechanical forces or
surface irregularities in data storage disk 126 may cause the
surface of data storage disk 126 to fluctuate in the positive or
negative .beta. direction. For example, an unexpected mechanical
force applied to data storage disk 126 may cause data storage disk
126 to move from its normal direction shown in FIG. 10b in the
positive or negative .beta. directions by an error distance Ed. To
ensure that enough space is available for focus arm 146 to rotate
and bring lens 156 in focus with data storage disk 126 when data
storage disk 126 is subjected to dynamic factors, actuator assembly
134 should be mounted to base 104 and/or gap G should take into
account Ed. In one embodiment, actuator assembly 134 should be
mounted and/or gap G should be formed so that:
A>Ed, and (1)
B>Ed (2)
[0066] Ed may vary over the distance between the center of data
storage disk 126 and the outer edge of data storage disk 126, with
the magnitude of Ed being the greatest at the outer edge of data
storage disk 126. Ed should be selected in accordance with the
maximum position of actuator assembly 134 in the negative .theta.
direction. A budget for Ed can be assessed for L.
[0067] As noted above, upper focus stop 140 functions to prevent
contact between lens 156 and data storage disk 126. To ensure that
lens 156 does not come into contact with data storage disk 126 even
when the disk is deflected in the positive .beta. direction and
focus arm 146 rotates in the negative .beta. direction from its
normal position, actuator assembly 134 should be mounted to base
104 and/or gap G should be formed so that:
A<(L-Ed) (3)
[0068] The components that form system 100 are subject to
manufacturing tolerances. For example: the thickness of actuator
assembly 134 from the top of lens 156 to the bottom of carbon fiber
layer 176a may vary within a tolerance from actuator assembly to
actuator assembly. These tolerances are static in nature for a
given component. However, the static tolerances in components
between and including lens 156 and data storage disk 126 should be
taken into account when selecting distances A and B. Thus, actuator
assembly 134 should be mounted to base 104 and/or gap G should be
formed so that:
A>Ed+Et, (4)
B>Ed+Et, and (5)
A<(L-Ed-Et), (6)
[0069] where Et represents the tolerances in components of the
system between and including the focus lens 156 and data storage
disk 126.
[0070] With reference to FIG. 10b, lens 156 is positioned close to
extensions 190a and 190b in the radial direction as measured from
axis 152. A and B are measured with respect to the points of
extensions 190a and 190b that engage lower focus stop 212 and upper
focus stop 140, respectively. Ideally, the radial distances,
measured with respect to the axis line 152 (FIG. 9a) of lens 156
and points on extensions 190a and 190b that engage lower focus stop
212 and upper focus stop 140, respectively, should be as close to
each other as possible. Because the radial distances of lens 156
and points on extensions 190a and 190b that engage lower focus stop
212 and upper focus stop 140, respectively, are relatively long,
the rotational travel of the points of extensions 190a and 190b
substantially equals the rotational travel of lens 156. Thus,
mounting actuator assembly 134 and/or forming gap G in accordance
with equations (4)-(6) above ensures that lens 156 will not contact
data storage disk 126, and that focus arm 146 has sufficient room
to travel in the positive or negative .beta. directions to bring
lens 156 into focus with data storage disk 126 should data storage
disk 126 vary from its normal position.
[0071] As mentioned above, actuator assembly 134 is capable of
rotation about pivot pin 142 in the positive or negative .theta.
direction as shown, for example, in FIGS. 7b or 8b. Actuator
assembly 134 includes tracking coil 170, which is a part of the
rotation motor for rotating the actuator assembly about pivot pin
142. The rotation motor also includes an array of permanent
rotation magnets (not shown) mounted indirectly to base 104 above
tracking coil 170. A variably controlled electrical current is
provided to tracking coil 170 via flex circuit 202 (FIGS. 7a and
7b). The variably controlled currents provided to focus coil 172
and tracking coil 170 originates with the system electronics. The
variably controlled current flowing through tracking coil 170
creates a variably controlled magnetic field that interacts with
the permanent magnetic field created by the array of permanent
rotation magnets. The interaction of these magnetic fields causes
actuator assembly 134 to controllably rotate about actuator
assembly pivot pin 142 in the positive or negative .theta.
directions depending on the magnitude and/or polarity of current
provided to tracking coil 170. Through this action, lens 156 of OPU
154 may be controllably positioned underneath any of the concentric
data tracks of data storage disk 126 for the purpose of reading or
writing data thereto.
[0072] Although actuator assembly 134 is rotatable in the positive
and negative .theta. directions, this rotation should be limited
for a variety of reasons. For example, rotation of actuator
assembly 134 should be limited to prevent contact between actuator
assembly 134 and cylinder 130. If contact occurs, damage may result
to actuator assembly 134 or cylinder 130. FIGS. 7a-7d illustrate
one embodiment of a device for adjustably limiting the positive
.theta. movement of actuator assembly 134. More particularly, FIGS.
7a-7d show an exemplary eccentric cam 220 rotatably mounted onto
base 104. In the embodiment shown, eccentric cam 220 includes a
camming surface 222 that, when engaging tracking coil 170, prevents
contact between actuator assembly 134 and cylinder 130. It is noted
that eccentric cam 220 is shown mounted vertically on base 104. In
the alternative, eccentric cam may be mounted horizontally to base
104.
[0073] Because eccentric cam 220 is rotatable on base 104, the
rotational limit of actuator assembly 134 is adjustable. The point
on camming surface 222 that engages tracking coil 170 corresponds
to the rotational limit of actuator assembly 134. As eccentric cam
220 is rotated, a different point on camming surface 222 can be
selected to engage tracking coil 170. By rotating eccentric cam 220
clockwise (i.e., in the positive .theta. direction), actuator
assembly 134 can rotate further in the positive .theta. direction
so that OPU 154 can read or write data to concentric data tracks
which are closer to a center point of data storage disk 126. FIGS.
7c and 7d show eccentric cam 220 in different positions. In FIGS.
7c and 7d, eccentric cam 220 engages actuator assembly 134 thereby
inhibiting further rotation thereof in the positive .theta.
direction. Contrasting FIGS. 7c and 7d illustrates the effect of
adjusting eccentric cam 220 and thus the rotational limit of
actuator assembly 134.
[0074] In the embodiment shown, eccentric cam 220 is manually
rotatable on base 104. In another embodiment, a motor may be
mounted to base 104 for rotating eccentric cam 220 in response to
signals generated internally by electronics of system 100 or
signals externally received by system 100.
[0075] The position of eccentric cam 220 may coincide with the
innermost data track of data storage disk 126. In other words, with
eccentric cam 220 engaging actuator assembly 134 at tracking coil
170, lens 156 may be positioned under the innermost data track of
data storage disk 126. This innermost data track often contains
important information about data storage disk 126. While eccentric
cam 220 engages tracking coil 170, focus arm 146 is free to rotate
about axis 152 and bring lens 156 in focus with the innermost data
track on data storage disk 126.
[0076] FIGS. 7c and 7d show eccentric cam 220 placed on base 104 to
engage tracking coil 170. The position of eccentric cam 220 need
not be limited to that shown. For example, eccentric cam 220 can be
repositioned on base 104 to engage tracking coil arm 184a.
Alternatively, eccentric cam 220 can be repositioned to engage
tracking arm 150 near axis line 152. Eccentric cam 220 could be
also be mounted, directly or indirectly, to base 104 to engage
focus arm 146 before actuator assembly 134 engages cylinder 130.
Once engaged in this alternative embodiment, focus arm 146 will
experience friction with the engaging eccentric cam 220 as the
focus motor attempts to rotate focus arm 146 in the positive or
negative .beta. directions to bring lens 156 into focus with the
innermost data track of data storage disk 126. The friction may
prevent lens 156 from being moved into focus with data storage disk
126. If enough current is provided to focus coil 172, the friction
may be overcome. However, attempts to focus lens 156 with data
storage disk 126 while focus arm 146 engages eccentric cam 220 (or
a similar device) may be erratic or slow, and may require a power
drain from, for example, a battery providing power to system 100.
With eccentric cam 220 engaging tracking coil 170 as shown in FIGS.
7c and 7d, no friction occurs between eccentric cam 220 and
tracking coil 170 as focus arm 146 rotates in the positive or
negative .beta. directions. Indeed, tracking arm 150 rotates only
in the positive or negative .theta. directions. Accordingly, there
are benefits to placing eccentric cam 220 on base 104 as shown in
FIGS. 7b-7c.
[0077] Although not shown, a second eccentric cam similar to
eccentric cam 220 may be mounted to base 104 to selectively adjust
the rotational limit of actuator assembly 134 in the negative
.theta. direction. In the embodiment shown, actuator 134 is limited
in the negative .theta. direction by a wall of base 104. With a
second eccentric cam rotatably mounted to the base 104 near, for
example, upper focus stop 140 and having a camming surface
configured to engage focus arm 146, the rotational limit of
actuator assembly 134 in the negative .theta. direction would also
be adjustable.
[0078] In the operative state, electrical current is provided to
focus coil 172 and/or tracking coil 170 of actuator assembly 134
while, for example, data is written to or read from data storage
disk 126. When current flows through focus coil 172 and/or tracking
coil 170, the magnetic field created by the focus coil 172 and/or
tracking coil 170 interacts with the magnetic fields created by the
permanent focus magnets 200a-200c and the permanent rotation
magnets, respectively. The interaction of the magnetic fields
maintains the position of actuator assembly 134. However, in the
non-operative state, no current is provided to focus coil 172
and/or tracking coil 170. As a result, no magnetic fields are
created by focus coil 172 and/or tracking coil 170 to maintain the
position of actuator assembly 134. In the non-operative state,
actuator assembly 134 may freely move in response to whatever force
is applied thereto. Free movement of actuator assembly 134 may
result in damage thereto as a result of, for example, shocks
experienced by actuator assembly 134 when it repeatedly bounces off
of upper focus stop 140 or eccentric cam 220.
[0079] Parking arm 136 (FIGS. 7a-7d) is an exemplary device for
preventing free movement, and thus damage, to actuator assembly 134
while it is in the non-operative state. As noted above, parking arm
136 is mounted to base 104 and is rotatably moveable about parking
pivot pin 160 between parked and unparked positions (FIGS. 7b and
7c). In one embodiment, a parking motor is provided for moving
parking arm 136 between the parked and unparked positions.
[0080] With reference to FIGS. 11a-11d, parking arm 136 includes a
steel plate 230, a counterweight 232, an arm 234, a wedge 236, a
permanent parking magnet 240, a magnet housing 242, and a parking
pivot pin 160. Magnet 240 can be more clearly seen in FIGS. 11b and
11d. Steel plate 230 operates to complete a magnetic circuit
created by magnet 240 and a steel plate 246 (FIGS. 12 and 13), as
more fully described below.
[0081] In one embodiment, arm 234, magnet-housing 242, and wedge
236 may be integrally formed, for example, from an thermoplastic
material such as nylon, teflon, delrin, or a teflon filled
polycarbonate. An aperture formed through arm 234 fixedly receives
parking pivot pin 160. Counterweight 232 is also fixedly attached
to arm 234 and acts to balance rotation of parking arm 136 about
pivot pin 160 when parking arm 136 is mounted to base 104.
[0082] Steel plate 230 and permanent parking magnet 240 of parking
arm 136 are also exemplary components of the parking motor
mentioned above. FIG. 12 is a perspective view of system 100 shown
in FIG. 7a with actuator assembly 134, upper focus stop 140, and
parking arm 136 removed to show other exemplary components of the
parking motor. More specifically, FIG. 12 shows a parking wire coil
244 and steel plate 246. Parking coil 244 is a component of an
electromagnet. FIG. 13 shows a perspective view of parking coil 244
and steel plate 246. Parking coil 244 and steel plate 246 are
mounted to the PCB which, in turn, is mounted to the underside of
base 104. Parking coil 244 includes wire leads 250a and 250b that
are coupled to bond pads (not shown) of the PCB so that system
electronics can provide current to parking coil 244 without an
intervening flex circuit, like the flex circuit that transmits
current to focus and tracking coils 172 and 170, respectively.
Parking coil 244 and steel plate 246 extend through apertures in
base 104 to take the position shown in FIG. 12.
[0083] Operational aspects of the parking motor will be explained
with reference to FIGS. 14a through 14f. However, before
operational aspects of the parking motor are explained, some
background on the creation of Lorentz forces may be helpful. FIG.
14f shows a length of wire 248 from parking coil 244 through which
electric current i.sub.cw flows. Current i.sub.cw is selectively
provided by system electronics. Although parking magnet 240 is not
shown in FIG. 14f, parking magnet 240 creates a magnetic field B
that envelopes wire length 248. For purposes of explanation, FIG.
14f shows only one flux line 250 of the magnetic field B passing
through wire length 248. The exact orientation of the magnetic
field B on each length of wire of parking coil 244 is slightly
different, as the flux lines of magnetic field B are not all
parallel or straight and are not of equal magnitude.
[0084] The interaction of i.sub.cw with magnetic field B creates a
Lorentz force F.sub.cw. F.sub.cw acts on wire length 248 in a
direction 90 degrees to the direction of i.sub.cw and in a
direction perpendicular to the plane defined by the current
i.sub.cw vector and the magnetic field B vector. The magnitude of
F.sub.cw is proportional to the magnitude of B, the length of the
wire, and the magnitude of i.sub.cw Since parking coil 244 is
fixedly connected to the base 104 via a printed circuit board,
F.sub.cw cannot move parking coil 244. The total Lorentz force FC
acting on parking coil 244 is the sum of the Lorentz forces
F.sub.cw for each wire leg of parking coil 244.
[0085] FIGS. 14a and FIG. 14b show isolated cross-sectional views
of parking arm 136, parking coil 244 and steel plate 246 in the
unparked state. FIGS. 14c, 14d, and 14e show isolated
cross-sectional views of parking arm 136, parking coil 244 and
steel plate 246 in the parked state. As noted, parking arm 136 is
capable of rotation about parking pivot pin 160 in the positive and
negative .theta. directions between the parked and unparked
states.
[0086] FIG. 14e shows parking arm 136 in the parked state with no
current i.sub.cw flowing through parking coil 244. As noted above,
parking arm 136 secures actuator assembly 134 from movement. In the
parked state, counterweight 232 counterbalances parking arm 136 at
pivot pin 160 so that parking arm 136 will not rotate out of the
parked state if system 100 experiences an external mechanical shock
in any direction in the .theta. plane. Additionally, because
parking arm 136 rotates in the positive or negative .theta.
directions (i.e., in the .theta. plane), parking arm 136 should be
able to withstand mechanical shocks in a direction perpendicular to
the .theta.0 plane.
[0087] In FIG. 14e, F2 represents the force of attraction between
base steel plate 246 and parking magnet 240. F2 consists of
orthogonal F2.sub..theta. and F2.sub..beta. components. With
continued reference to FIG. 14e, FIG. 14d illustrates that a
Lorentz force F.sub.cw, described above with reference to FIG. 14f,
is created when current i.sub.cw is first provided to parking coil
244 by system electronics. For purposes of explanation, FIG. 14f
shows only one Lorentz force F.sub.cw acting on one wire segment
248 of coil 244. When all the Lorentz forces F.sub.cw acting on
respective wire segments of parking coil 244 are summed, a
collective Lorentz force FC is created. A force F1 equal and
opposite to FC, is created when FC is created. F1 acts on parking
arm 136. For purposes of explanation, FIG. 14d shows only F1.sub.74
, the .theta. component of F1, it being understood that an
orthogonal .beta. component of F1 is also created. F1.sub..theta.
is equal and opposite to FC.sub..theta..
[0088] With continued reference to FIGS. 14d and 14e, FIG. 14c
shows both forces F1.sub.74 and F2 acting on parking arm 136 when
current i.sub.cw is first provided to parking coil 244.
Additionally, FIG. 14c shows frictional force Ff acting on parking
arm 136. As noted above, F1.sub..theta. results from current
i.sub.cw flowing through coil 244 in the presence of magnetic field
B. F1.sub..theta. is in a direction opposite to F2.sub..theta., one
of the orthogonal components of F2. Ff is in the same direction as
F2.sub..theta. and results from friction between the parking arm
136 and, for example, base 104. The frictional force Ff can be
calculated as a function of F2.sub..beta. and the coefficient of
friction Mu between, for example, the parking arm 136 and base
104.
[0089] To unpark parking arm 136 from the parked state,
F1.sub..theta. should exceed F2.sub.74 plus Ff. It is a design goal
to unpark parking arm 136 with the lowest current i.sub.cw possible
to save power. This can be done by increasing the magnetic field B,
the number of turns times current, minimizing the gap between
parking coil 244 and parking magnet 240, and/or minimizing the
coefficient of friction Mu between the parking arm 136 and base
104.
[0090] FIG. 14b shows parking arm 136 in the unparked state. As
will be more fully described below, parking coil 244 is energized
with current i.sub.cw to maintain parking arm 136 in the unparked
state. The magnitude of current i.sub.cw to maintain parking arm
136 in the unparked state should be less than the magnitude of
i.sub.cw needed to unpark parking arm 136. In FIG. 14b the
interaction of i.sub.cw flowing through wire 248 and the magnetic
field B creates Lorentz force F.sub.cw. For purposes of
explanation, FIG. 14b shows only one Lorentz force F.sub.cw 248
acting on wire segment 252 of coil 244 through which current
i.sub.cw flows. When all the Lorentz forces F.sub.cw acting on
respective wire segments of parking coil 244 are summed, a
collective Lorentz force FC is created. A force F1 that is equal
and opposite to FC, is created when F1 is created. F1 acts on
parking arm 136. For purposes of explanation, FIG. 14b shows only
the .theta. components of F1 and FC, it being understood that
orthogonal .beta. components of F1 and FC are also created.
[0091] FIG. 14a shows F1.sub..theta. resulting from the current in
the coil 24 (FIG. 14b) as well as F2 which is the attractive force
of the magnets to the base steel plate 246. F2.sub..theta., the
horizontal component of F2, works in the direction opposite that of
F1.sub..theta.. Because parking magnet 240 is positioned further
away from the parking coil 244 in the positive .theta. direction,
the magnitude of force vector F2.sub..theta. is greater than that
shown in FIG. 14c. The result is a stronger F2.sub..theta. to park
the parking arm 136 when coil 244 is de-energized.
[0092] When coil 244 is de-energized, F1 is eliminated. When
parking arm 136 parks focus arm 146, F.sub.f appears. Here, F.sub.f
will be in the direction opposite that of F2.sub..theta. and have a
magnitude of F2.sub..beta. multiplied by Mu. Thus, the parking arm
136 will park when:
F2.sub..theta.>F2.sub..beta.*Mu, or F2.sub..theta.>F.sub.f,
(7)
[0093] The magnitude of F2.sub..theta. in FIG. 14c is smaller than
in FIG. 14a, since the parking magnet 240 is nearly aligned
vertically with base plate 246 in FIG. 14c. In other words, the
attractive force between the parking magnet 240 and base plate 246
is largely in the .beta. direction in FIG. 14c. It is noted that F1
and F2 in FIG. 14a are different than F1 and F2 shown in FIG.
14c.
[0094] FIG. 15 is a cross-sectional view of system 100 shown in
FIG. 7b taken along line DD thereof and illustrates operational
aspects of parking actuator assembly 134. When current I1 to
parking coil 244 is terminated, F1 is eliminated. Force
F2.sub..theta. causes parking arm 136 to rotate in the positive
.theta. direction and drive wedge 236 into the gap between
extension 190b and upper focus stop 140. Force F2.sub..theta. is
sufficient in magnitude to drive wedge 236 into the gap between
extension 190b and upper focus stop 140, after (1) wedge 236 first
engages upper focus stop 140, or (2) wedge 236 first engages
extension 190b. Thus, F2.sub..theta. causes wedge 236 to slide
against the bottom surface of upper focus stop 140 or extension
190b after wedge 236 first engages upper focus stop 140 or
extension 190b. While wedge surface 238 slides against extension
190b, focus arm 146 rotates about axis 152 (FIG. 8a) in the
negative .beta. direction until the bottom surface of extension
190a engages lower focus stop 212 of base 104 (FIG. 10b). With the
bottom surface of extension 190a engaging lower focus stop 212,
wedge surface 238 may continue to slide against extension 190b
until wedge 236 engages upper focus stop 140.
[0095] As shown in FIG. 15, with wedge 236 engaging both extension
190b and upper focus stop 140, extension 190a engaging lower focus
stop 212, and F2.sub..theta. applied to parking arm 136, a
compressive force is created in the stack consisting of the base
104, focus arm 146, wedge 236 and upper focus stop 140 that parks
or inhibits movement of actuator assembly 134. Frictional force
between extension 190b and wedge 236, and frictional force between
extension 190a and base 104 inhibit rotation of actuator assembly
134 in the positive or negative .theta. directions.
[0096] At some point, with electrical current applied to focus coil
172 parking arm 136 will unpark actuator assembly 134 so that
actuator assembly 134 may move in response to forces created by the
rotation and focus motors. It is noted actuator assembly 134 will
be in substantially the same .theta. position it was before it was
parked.
[0097] Although not shown, a raised portion may be formed on wedge
236 at position 252 shown in FIGS. 11a and 11c. Ideally, this
raised portion would have a rounded surface that engages upper
focus stop 140 while parking arm 136 parks actuator assembly 134.
The raised portion would operate to reduce friction between the
parking arm 136 and upper focus stop 140.
[0098] It is noted that extension 190b is shown with a right-angled
edge that engages wedge surface 238. In the alternative, this edge
may be beveled to reduce the friction between wedge surface 238 and
extension 190b. It is also noted that frame 144 includes carbon
fiber layer 176a having extension 190a. In the alternative, carbon
fiber layer 176a could be eliminated so that extension 190b engages
surface (lower focus stop) 212 while actuator assembly 134 and
parking arm 136 are in the parked state.
[0099] With reference to FIGS. 7a and 12, spindle motor 116 is
mounted to a surface of base 104 opposite to that shown in FIG. 7a.
For purposes of definition, two components can be mounted, coupled,
or connected together directly or indirectly via one or more
intermediate components. Cylinder 130 of spindle motor 116 extends
through an aperture in base 104 and is rotatable therein. As noted
above, when data cartridge 102 is fully loaded in system 100,
cylinder 130 engages and rotates data storage disk 126. Z-datums
132a-132d define raised surfaces of base 104. When data cartridge
102 is fully loaded in system 100, the cartridge shell 120 (FIG. 4)
rests on z-datums 132a-132d while spindle motor cylinder 130
rotates data storage disk 126. To ensure that data storage disk 126
rotates freely in cartridge shell 120, spindle motor 116 should be
mounted to base 104 so that z-datums 132a-132d are contained in a
plane that is parallel to and separated by a length R from a plane
that defines the top of cylinder 130.
[0100] FIG. 16a is a top view of a tool 260 for mounting spindle
motor 116 to base 104. FIG. 16b is a cross-sectional view of tool
260 shown in FIG. 16a taken through line EE thereof. Tool 260, in
one embodiment, is integrally formed from steel or other rigid
material that is attracted to a magnet. With continued reference to
FIG. 16b, tool 260 has oppositely facing top and bottom surfaces
262 and 264, respectively. Bottom surface 264 should be flat or
substantially flat. A disk shaped recess 266 is formed in the
bottom surface 264. A recess sidewall 270 and a recess surface 272
define recess 266. Recess surface 272 should be flat or
substantially flat and parallel or substantially parallel to bottom
surface 264. Recess surface 272 should be separated from bottom
surface 264 by length R, the same length that separates the plane
containing z-datums 132a-132d from the plane that contains the top
of cylinder 130. Lastly, tool 260 includes an aperture 274
extending between the top and bottom surfaces 262 and 264. Tool
aperture 274 is sized to receive pin 264 extending from z-datum
132c (FIG. 12).
[0101] With continued reference to FIGS. 16a and 16b, FIG. 16c
shows an exploded perspective view of tool 260, base 104, and
spindle motor 116. Base 104 includes an aperture 280 through which
cylinder 130 extends when spindle motor 116 is mounted. Tool 260 is
securely positioned on base 104 so that bottom surface 264 engages
z-datums 132a-132d and datum pin aperture 274 receives datum pin
276. A clamp (not shown) can be used to secure the position of tool
260 on base 104. FIG. 16d is a top view of tool 260 securely
positioned on base 104.
[0102] An adhesive such as a UV light sensitive adhesive is applied
to base to motor bonding surface 268 and/or spindle motor bonding
surface 278. ASEC 550 LVUV-J is one UV light sensitive adhesive
that may be used. The amount of applied adhesive should be enough
to coat bonding surfaces 268 and/or 278, but should be limited to
prevent squeeze out of adhesive between bonding surfaces 268 and
278 when spindle motor is mounted to base 104. Thereafter, cylinder
130 is inserted through base aperture 280 until the top of cylinder
130 engages recess surface 266 of tool 260. In this position,
bonding surfaces 268 and 278 engage each other with a thin layer of
adhesive therebetween. It should be noted cylinder 130 may be
inserted through base aperture 280 before tool 260 is positioned on
z-datums 132a-132d. It should also be noted that the adhesive might
be applied to bonding surfaces 268 and/or 278 after cylinder 130 is
inserted through base aperture 280. In this latter embodiment, a
small gap is created between bonding surfaces 268 and 278 into
which the adhesive is wicked. More particularly, adhesive is
provided at the end of the gap between adjacent bonding surfaces
268 and 278. The adhesive is then drawn into the gap by capillary
action between the bonding surfaces 268 and 278 until the gap is
filled or substantially filled.
[0103] FIG. 16e is a cross-sectional view taken along line FF of
FIG. 16d. FIG. 16e shows cylinder 130 extending through base 104
and engaging recess surface 272, datum pin 276 received in datum
pin aperture 274, and bottom surface 264 engaging z-datum 132c. A
disk chuck 282 of spindle motor 116 magnetically attracts spindle
motor 116 to tool 260 and operates to maintain contact between
cylinder 130 and recess surface 272. With cylinder 130 engaging
tool 260, the top of cylinder 130 is in proper alignment with
z-datums 132a-132d. In other words, with cylinder 130 engaging tool
260, the plane containing the top of cylinder 130 is substantially
parallel to and separated by R from the plane containing z-datums
132a-132d.
[0104] While the base 104, motor 116, and tool 260 are in position
shown in FIG. 16e, the adhesive between base 104 and spindle motor
116 is cured to create a fixed bound therebetween. For example, UV
light is applied to the UV light sensitive adhesive between base
104 and spindle motor 116 for approximately 10 to 30 seconds to
first create a tacked bond between base 104 and spindle motor 116.
When the adhesive is wicked into the gap between bonding surfaces
268 and 278, a UV cured surface may be formed on the adhesive. This
UV cured surface may prevent oxygen from passing therethrough.
Without oxygen, the remaining adhesive between bonding surfaces 268
and 278 may experience anaerobic curing to further bond the
surfaces. The tacked and/or anaerobic bond is not strong, but
strong enough to maintain alignment of the spindle motor through a
thermal cure process to create a stronger bond. The process for
creating the fixed bond can vary from 15 minutes to several hours
depending on the process. After the fixed bond is created, tool 260
is separated from base 104.
[0105] Although the present invention has been described in
connection with several embodiments, the invention is not intended
to be limited to the specific forms set forth herein. On the
contrary, it is intended to cover such alternatives, modifications,
and equivalents as can be reasonably included within the spirit and
scope of the invention as defined by the appended claims.
* * * * *