Load and unload ramp with integrated latch

A ramp loading and unloading system for the heads in a disc drive including an integrated latching mechanism for the disc drive actuator. The flexures that support the heads include ramp contact features which engage the ramps, and at least one of the ramp contact features includes a vertical latching face. At least one of the ramps includes a discontinuity forming a ramp latching face with which the vertical latching face of the ramp contact feature engages to latch the actuator. The ramp structure also includes a pivoting member which is rotated under influence of the actuator to allow the latching faces of the flexure and ramp structure to disengage.

FIELD OF THE INVENTION 
This invention relates generally to the field of hard disc drive data 
storage devices, and more particularly, but not by way of limitation, to 
an improved ramp system for unloading the heads of a disc drive from 
engagement with the discs and an actuator latching mechanism for holding 
the actuator mechanism of the disc drive at a park position on the ramps 
in the absence of power. 
BACKGROUND OF THE INVENTION 
Disc drives of the type known as "Winchester" disc drives, or hard disc 
drives, are well known in the industry. Such disc drives magnetically 
record digital data on a plurality of circular, concentric data tracks on 
the surfaces of one or more rigid discs. The discs are typically mounted 
for rotation on the hub of a brushless DC spindle motor. In disc drives of 
the current generation, the spindle motor rotates the discs at speeds of 
up to 10,000 RPM. 
Data are recorded to and retrieved from the discs by an array of vertically 
aligned read/write head assemblies, or heads, which are controllably moved 
from track to track by an actuator assembly. The read/write head 
assemblies typically consist of an electromagnetic transducer carried on 
an air bearing slider. This slider acts in a cooperative hydrodynamic 
relationship with a thin layer of air dragged along by the spinning discs 
to fly the head assembly in a closely spaced relationship to the disc 
surface. In order to maintain the proper flying relationship between the 
head assemblies and the discs, the head assemblies are attached to and 
supported by head suspensions or flexures. 
The actuator assembly used to move the heads from track to track has 
assumed many forms historically, with most disc drives of the current 
generation incorporating an actuator of the type referred to as a rotary 
voice coil actuator. A typical rotary voice coil actuator consists of a 
pivot shaft fixedly attached to the disc drive housing base member closely 
adjacent the outer diameter of the discs. The pivot shaft is mounted such 
that its central axis is normal to the plane of rotation of the discs. An 
actuator bearing housing is mounted to the pivot shaft by an arrangement 
of precision ball bearing assemblies, and supports a flat coil which is 
suspended in the magnetic field of an array of permanent magnets, which 
are fixedly mounted to the disc drive housing base member. On the side of 
the actuator bearing housing opposite to the coil, the actuator bearing 
housing also typically includes a plurality of vertically aligned, 
radially extending actuator head mounting arms, to which the head 
suspensions mentioned above are mounted. When controlled DC current is 
applied to the coil, a magnetic field is formed surrounding the coil which 
interacts with the magnetic field of the permanent magnets to rotate the 
actuator bearing housing, with the attached head suspensions and head 
assemblies, in accordance with the well-known Lorentz relationship. As the 
actuator bearing housing rotates, the heads are moved radially across the 
data tracks along an arcuate path. 
The movement of the heads across the disc surfaces in disc drives utilizing 
voice coil actuator systems is typically under the control of closed loop 
servo systems. In a closed loop servo system, specific data patterns used 
to define the location of the heads relative to the disc surface are 
prerecorded on the discs during the disc drive manufacturing process. The 
servo system reads the previously recorded servo information from the 
servo portion of the discs, compares the actual position of the actuator 
over the disc surface to a desired position and generates a position error 
signal (PES) reflective of the difference between the actual and desired 
positions. The servo system then generates a position correction signal 
which is used to select the polarity and amplitude of current applied to 
the coil of the voice coil actuator to bring the actuator to the desired 
position. When the actuator is at the desired position, no PES is 
generated, and no current is applied to the coil. Any subsequent tendency 
of the actuator to move from the desired position is countered by the 
detection of a position error, and the generation of the appropriate 
position correction signal to the coil. 
When power to the disc drive is lost, servo control of the current flow in 
the coil of the voice coil actuator is lost. In the absence of DC current 
flowing in the coil, the actuator is free to move in response to such 
things as mechanical shock, air movement within the disc drive or 
mechanical bias applied to the actuator by the printed circuit cable (pcc) 
used to carry signals to the coil and to and from the heads mounted on the 
actuator. Since a power loss also means that the spindle motor will also 
cease to rotate the discs, the air bearing supporting the heads also 
begins to deteriorate and contact will be made between the heads and the 
discs. Because of this, it is common practice in the industry to monitor 
input power to the disc drive, and, at the detection of power loss, to 
drive the actuator to a park position and latch it there until power to 
the disc drive is restored. 
It is also well known to use the back electromotive force (BEMF) generated 
by the inertia of the spinning discs to generate the power to move the 
actuator to a park position, and the park position is typically selected 
to be at a location which places the heads closely adjacent the hub of the 
spindle motor. By parking the heads toward the inner diameter of the 
discs, the amount of power necessary to overcome the frictional drag of 
the heads on the discs at power-up is minimized. 
An alternative approach to protecting the heads and discs in the event of a 
power loss to the disc drive is to utilize a ramping system closely 
adjacent the outer diameter of the discs to remove the heads from 
engagement with the discs. The actuator is parked with the heads supported 
by the ramps and latched in this position until power to the disc drive is 
restored. Upon reestablishment of power to the disc drive, the actuator is 
unlatched, and the heads are loaded back into engagement with the discs 
onto an established air bearing. In disc drives utilizing such ramp 
loading and unloading systems, the heads and discs should never come into 
direct contact. 
The principal requirements of an actuator latch mechanism are that it hold 
the actuator at the park position in the presence of a defined maximum 
specified amount of mechanical shock during the time interval when power 
is not applied, and that the latching mechanism be capable of releasing 
the actuator once power has been reapplied to the disc drive and the 
spindle motor brought back up to operational speed. It is also desirable 
if the latching mechanism can be implemented with a minimal cost, both in 
mechanical and electronic components. 
Many forms of latches to hold the actuator at the park position have been 
used and are disclosed in the art. These include magnetic latches, 
solenoid-activated latches, shape-memory metal latches and aerodynamically 
activated latches. For a representative review of several prior art 
actuator latches, the reader is directed to U.S. Pat. No. 5,612,842, 
issued Mar. 18, 1997, U.S. Pat. No. 5,581,424, issued Dec. 3, 1996, U.S. 
Pat. No. 5,555,146, issued Sep. 10, 1996, U.S. Pat. No. 5,365,389, issued 
Dec. 15, 1994, U.S. Pat. No. 5,361,182, issued Dec. 1, 1994, U.S. Pat. No. 
5,313,354, issued May 17, 1994, U.S. Pat. No. 5,262,912, Dec. 16, 1993 and 
U.S. Pat. No. 5,231,556, issued Jul. 27, 1993, all assigned to the 
assignee of the present invention and all incorporated herein by 
reference. 
In latching mechanisms used in association with ramps, it is also desirable 
that the unlatching of the actuator does not require any sudden large 
acceleration of the actuator, since no servo control of the actuator 
exists until after the heads are repositioned in cooperative engagement 
with the discs. It is well known in the industry that the heads must be 
loaded off the ramps and onto the air bearing above the discs at a 
relatively low speed, to ensure that the air bearing is not overcome, 
allowing the heads to contact the disc surfaces. Any such head/disc 
contact greatly increases the possibility of damage to the heads, the 
discs or both. 
Clearly a need exists for a head loading and unloading ramp system which 
incorporates a simple latch mechanism for the actuator in a disc drive, 
which does not require expensive electronic control circuitry, which holds 
the actuator with sufficient force to withstand the maximum specified 
mechanical shock and which is easily released when power to the disc drive 
is restored. 
SUMMARY OF THE INVENTION 
The present invention is a ramp loading and unloading system for the heads 
in a disc drive that includes an integrated latching mechanism for the 
disc drive actuator. The flexures that support the heads include ramp 
contact features which engage the ramps, and at least one of the ramp 
contact features includes a vertical latching face. The ramps in the 
system include beveled portions that lift the heads vertically away from 
the disc surfaces as the heads are moved radially outward from the discs, 
and flat portions extending in parallel with the surfaces of the discs. At 
least one of the flat portions of one of the ramps includes a 
discontinuity forming a ramp latching face with which the vertical 
latching face of the flexure ramp contact feature engages to latch the 
actuator. Associated with the ramp having the latching face is a pivoting 
element which has a contact surface which is non-coplanar with the flat 
portion of the ramp in a first, or latched, quiescent position. The 
pivoting element also includes an unlatching contact feature at the outer 
end of its contact surface. Unlatching of the actuator is accomplished by 
driving the actuator first in an outward direction, moving the flexure 
ramp contact feature associated with the latching mechanism along the 
pivoting element contact surface and into contact with the unlatching 
contact feature. As the flexure ramp contact feature bears against the 
pivoting element unlatching contact feature, the pivoting element is 
rotated into a second, or unlatched, position with its contact surface 
substantially coplanar with the flat portion of the associated ramp. The 
actuator is then moved rapidly inward along the pivoting element contact 
surface until the flexure ramp contact feature is positioned inward of the 
latching face and in contact with the flat portion of the ramp. The 
pivoting element is allowed to return to its first quiescent latched 
position, enabling subsequent latching operations. From the flat portion 
of the ramps, the heads are moved back into engagement with the discs in a 
controlled manner. 
It is an object of the invention to provide a ramp system for unloading the 
heads of a disc drive from engagement with the discs and loading the heads 
back into engagement with the discs and a latching mechanism to hold the 
actuator of the disc drive at a park position with the heads supported by 
the ramps. 
It is another object of the invention to provide a latching mechanism which 
requires minimal additional electronic or electrical controls for latching 
or unlatching. 
It is another object of the invention to provide a latching mechanism that 
engages and disengages under influence of the actuator power source. 
These and other objects, features and advantages of the present invention 
can best be understood by a review of the following Detailed Description 
of the Invention, when read in conjunction with an examination of the 
accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION 
Turning now to the drawings and specifically to FIG. 1, shown is a partial 
plan view of a disc drive 100 in which the present invention is 
particularly useful. The disc drive 100 includes a base member 102 to 
which all other components are directly or indirectly mounted and a top 
cover 104 (shown in partial cutaway) which, together with the base member 
102, forms a disc drive housing which encloses delicate internal 
components and isolates these components from external contaminants. 
The disc drive includes a plurality of discs 106 which are mounted for 
rotation on a spindle motor shown generally at 108. The discs 106 include 
on their surfaces a plurality of circular, concentric data tracks, the 
innermost and outermost of which are shown by dashed lines at 110, on 
which data are recorded via an array of vertically aligned head assemblies 
(one of which is shown at 112). The head assemblies 112 are supported by 
head suspensions, or flexures 114, which are attached to actuator head 
mounting arms 116. The actuator head mounting arms 116 are integral to an 
actuator bearing housing 118 which is mounted via an array of ball bearing 
assemblies (not designated) for rotation about a pivot shaft 120. 
Power to drive the actuator bearing housing 118 in its rotation about the 
pivot shaft 120 is provided by a voice coil motor (VCM) shown generally at 
122. The VCM 122 consists of a coil 124 which is supported by the actuator 
bearing housing 118 within the magnetic field of an array of permanent 
magnets (not separately designated) which are fixedly mounted to the base 
member 102, all in a manner well known in the industry. Electronic 
circuitry (partially shown at 126, generally, and partially carried on a 
printed circuit board (not shown)) to control all aspects of the operation 
of the disc drive 100 is provided, with control signals to drive the VCM 
122, as well as data signals to and from the heads 112, carried between 
the electronic circuitry 126 and the moving actuator assembly via a 
flexible printed circuit cable (PCC) 128. 
The disc drive 100 also includes an arrangement of components for limiting 
the range of motion of the actuator. Specifically, the disc drive includes 
an inner limit stop 130. The inner limit stop 130 cooperates with a 
contact feature 134 integral to the coil 124 to define the innermost 
extent to which the actuator mechanism can move the heads 112. 
The disc drive also includes an array of ramps 136 which cooperate with 
ramp contact features, one of which is shown at 138. As can be seen, the 
ramp contact feature is a part of the flexure 114 which supports the heads 
112. The disc drive 100 of FIG. 1 is of the type which utilizes the ramps 
136 and ramp contact features 138 to remove the heads 112 from cooperative 
engagement with the discs 106 when a loss of power is detected. The 
operation of the ramps 136 and ramp contact features 138, as well as the 
operation of a latching mechanism used to maintain the heads on the ramps, 
will be discussed in more detail below. However, it can be noted from the 
figure that the heads 112 are longitudinally offset from the ramp contact 
features 138 of the flexures 114. In the case of the configuration shown 
in FIG. 1, the heads are further from the pivot shaft 120 than the ramp 
contact features 138. Because of this longitudinal offset, the heads 112 
themselves will not contact the ramps 136, and all head lifting is 
accomplished only by contact between the ramps 136 and the ramp contact 
features 138. This is necessary to prevent damage to the delicate gimbal 
components that mount the slider of the head and allow roll and pitch 
compliance. 
FIG. 1-1 shows an alternative configuration of head suspension or flexure 
140. With this flexure 140, the ramp contact feature 142 is located at the 
far distal end of the flexure 140, while the head 144 is supported by a 
gimbal apparatus (not shown) at a position between the ramp contact 
feature 142 and the pivot center of the actuator. An examination of FIG. 
1-1 reveals that the ramps 146 which interact with the ramp contact 
features 142 are mounted closely adjacent the outer diameter of the discs 
106, and that the ramp contact features 142 are again offset from the 
heads 144 along the longitudinal axis 148 of the flexures 140, although in 
the opposite direction from the configuration of FIG. 1. FIG. 1-1 also 
shows that the ramps 146 are integrally formed with head protection 
surfaces 139. These head protection surfaces 139 are substantially 
coplanar with the discs 106 and, as such will lie between facing heads 144 
when the flexure ramp contact features 142 have contacted and moved onto 
the ramps 146. In this location, the head protection surfaces 139 prevent 
contact between facing heads 144 that might cause damage to the heads 144. 
More discussion of the head protection surfaces 139 will be found in the 
following discussion. 
FIG. 2-1 is a simplified elevation view showing the relevant components of 
a disc drive and a prior art ramp system for unloading and loading the 
heads. FIG. 2-1 shows the outermost portion of three discs, one of which 
is designated 106, and six heads, one of which is designated 112, 
cooperatively engaged with the surfaces of the discs 106. The heads 112 
are mounted to and supported by flexures, one of which is designated 114, 
and the flexures can be seen to each include a ramp contact feature 138 
extending laterally from the flexures 114. The person of skill in the art 
will realize that the specific number of discs 106 and heads 112 in the 
figures is selected for purposes of illustration only in this and all 
subsequent discussion, and thus should not be considered as limiting to 
the scope of the invention. 
FIG. 2-1 also shows a ramp structure 136 such as that shown in FIG. 1. The 
ramp structure 136 can be seen to be made up of a plurality of ramp 
fingers 150, each of which serves to interact with a pair of facing ramp 
contact features 138, and each side of which includes a flat portion 152 
and a beveled portion 154. The left ends of the ramp fingers 150 are 
joined by a backing member 156 in a comb-like manner, while the right ends 
of the ramp fingers 150 each lie opposite a disc 106. 
FIG. 2-1 shows the component relationship that exists when the actuator has 
moved the heads 112 outward to the point where contact between the flexure 
ramp contact features 138 and the beveled portion 154 of the ramp fingers 
150 is first made. The heads 112 are shown in their operational 
relationship to the discs 106, flying on an air bearing (not visible at 
the scale of the drawing) above the disc surfaces. 
FIG. 2-2 shows a similar prior art ramping system, and represents the 
component relationship that exists as the actuator continues to move the 
flexures 114 and heads 112 outward from the outer diameter of the discs 
106. Specifically, FIG. 2-2 shows that the heads have been moved outward 
until the flexure ramp contact features 138 have reached the juncture of 
the beveled portions 154 and flat portions 152 of the ramp fingers 150. A 
comparison of FIG. 2-1 to FIG. 2-2 clearly shows that, as the actuator 
moves the heads 112 outward, the beveled portions 154 of the ramp fingers 
150 serve to lift the heads away from the plane of the disc surfaces. In 
this manner, the heads 112 are moved away from the discs 106 in both the 
vertical and horizontal axes of the figure. If it is recalled that this 
ramp unloading of the heads is typically performed in response to the 
detection of power loss, it is apparent that such ramp unloading of the 
heads will prevent any contact between the heads and discs as the discs 
decelerate to a stop. 
FIG. 2-2 also shows the presence of head protection surfaces 139, one of 
which extends toward the viewer from the lateral surface of each ramp 
finger 150. The head/flexure configuration in the figure is assumed to be 
similar to that of FIG. 1, i.e., the heads 112 are located farther from 
the pivot point of the actuator than the flexure ramp contact features 
138, and thus closer to the viewer in the figure. It is also evident from 
the figure that, as the heads 114 and flexures 114 are moved outward and 
up the beveled portions 154 of the ramp fingers 150, the heads 106 whose 
operational surfaces face each other will be separated by one of the head 
protection surfaces. It is known to those of skill in the art that the 
heads 106, unsupported by an air bearing, will be free to move to a 
relatively large extent as a result of applied mechanical shocks when 
parked on the ramp, and it is also known that uncontrolled contact between 
facing heads can cause damage to one or the other of the contacting heads, 
or both. The head protection surfaces 139 are typically formed of the same 
material as the other ramp elements, and this material is typically a 
plastic, polymer resin or "hard" elastomer, all of which are significantly 
softer than the calcium titanate, or other very hard, brittle material, 
from which the sliders of typical heads are formed. Therefore, the head 
protection surfaces of the figure serve not only to prevent head-to-head 
contact, but also provide a relatively soft surface for head contact as a 
result of applied mechanical shocks. 
FIG. 2-3 shows a ramping system similar to that of FIG. 2-1 and FIG. 2-2, 
and illustrates the component relationships when the actuator has moved 
the heads 112 further outward from the discs 106. In moving from the 
position of FIG. 2-2 to the position of FIG. 2-3, the heads 112 and 
flexures maintain the same vertical relationship, since the flexure ramp 
contact features are moving along the parallel flat portions 152 of the 
ramp fingers 150. Prior art disc drives have typically utilized such 
ranges of linear parallel motion of the actuator components to provide 
motion necessary to engage some sort of actuator latch used to hold the 
actuator at a park position. 
FIG. 2-4 shows a common prior art actuator latching scheme that is 
incorporated in disc drives using head unloading ramps. In FIG. 2-4, it 
can be seen that the flat portions 156 of the ramp fingers 150 have been 
modified to include indentations or detents 158 at some point along their 
lengths. As the actuator moves outward, the flexure ramp contact features 
138 encounter these detents 158 and the load force of the flexures 114, 
which acts to encourage the heads 112 toward the disc surfaces, causes the 
flexure ramp contact features 138 to engage the detents 158, as shown. 
Such detent actuator latching systems have been use quite frequently in 
the art since the only modification needed is the inclusion of the detents 
158. 
A careful analysis of FIG. 2-4, however, will reveal that such detent 
latching schemes are usually unsatisfactory compromises between the amount 
of latching force available to hold the actuator against movement as a 
result of applied mechanical shocks and the amount of force necessary to 
move the actuator away from the detents when power is restored. The figure 
shows the flexure ramp contact features 138 as having angled faces, and 
the detents 158 are also shown to have angled faces. While angling the 
contact surfaces of the flexure ramp contact features 138 and the detents 
158 facilitates the unlatching of the actuator, it also serves to make the 
latch easier to unintentionally unlatch due to applied mechanical shocks. 
Furthermore, if the contact surfaces were to be made more vertical, the 
latch would be more resistant to unintended unlatching, but more difficult 
to unlatch. Indeed, if the latching contact surfaces were truly 
perpendicular to the flat portion 154 of the ramp fingers 150, it would be 
impossible to unlatch the actuator without providing some additional 
apparatus to lift the flexure vertically, thus adding cost and complexity 
to the disc drive. The present invention provides a vertical latching 
contact surface to maximize the latching force applied to the actuator, 
and then makes use of available force applied by the actuator motor to 
move the flexure latch contact surface away from the vertical latch face 
during unlatching operations. 
Turning now to FIGS. 3-1 and 3-2, shown are two versions of a ramp 
structure 160, 162 which form a part of the ramp and latching system of 
the present invention. The two versions of ramp structure 160, 162 differ 
only in the type of flexure with which they are intended to be used. 
Specifically, the ramp structure 160 of FIG. 3-1 is intended for use with 
a flexure configuration similar to that shown in FIG. 1, that is, a 
flexure configuration in which the flexure ramp contact feature (138 in 
FIG. 1) lies between the head (112 in FIG. 1) and the actuator pivot 
point, while the ramp structure 162 of FIG. 32 is intended for use with 
flexure configurations similar to that of FIG. 1-1, or flexures which 
mount the head (144 in FIG. 1-1) between the flexure ramp contact feature 
(142 in FIG. 1-1) and the actuator pivot point. Thus the following 
discussion will refer to similarly numbered features in both FIG. 3-1 and 
FIG. 3-2. 
The ramp structures 160, 162 of FIG. 3-1 and FIG. 3-2 include a backing 
member 164 from which a number of ramp fingers 150, 166 are cantilevered. 
The ramp fingers 150 are similar to those described above in relationship 
to FIG. 2-1 through FIG. 2-4, i.e., they include beveled portions 154 and 
flat portions 152, intended for interaction with flexure contact features 
(138, 142 in FIG. 1 and FIG. 1-1, respectively) in the manner described 
above for the prior art. 
The topmost ramp finger 166 also includes beveled portions 154, and, on its 
lower side, a flat portion 152 of similar function to the prior art. It is 
on the upper side of the ramp finger 166 that differences associated with 
the present invention occur. Examination of FIG. 3-1 and FIG. 3-2 reveals 
that the upper side of ramp finger 166 includes a shortened flat portion 
168 which is terminated by a discontinuity or vertical latching surface 
170. The manner in which the latching surface 170 is used to latch the 
actuator will be discussed in more detail below. From the figures, it can 
be seen that the structure of the upper side of the ramp finger 166 then 
extends in parallel with the flat portions 154, 168 of the ramp fingers 
150, 166 from the base of the latching surface 170 to the backing member 
164. 
The ramp structures 160, 162 also include a pivoting member 172. This 
pivoting member 172 is connected to the backing member 164 by a thin, 
flexible hinge element 174. The pivoting member 172 is shown in the 
figures in its quiescent position and is free to pivot relative to the 
backing member 164 and the ramp fingers 150, 166 at the flexible hinge 
element 174. The allowed range of motion of the pivoting member 172 in the 
upward direction is limited by an upward contact pin 176 extending from 
the lateral surface of the top ramp finger 166 and a pivot contact feature 
178. A similar downward contact pin (hidden from view in FIG. 3-1 and FIG. 
3-2) will be shown in other figures and limits the downward rotation of 
the pivoting member 172 to the quiescent position shown. 
The pivoting member 172 also includes a pivoting ramp surface 180 and an 
unlatching contact feature 182. The operation of the pivoting member 172 
and its interaction with other system elements will be discussed in detail 
below. 
FIG. 4-1 shows a first configuration of a ramp contact/latching feature 184 
that is another element of the ramp and latching system of the present 
invention. A person of skill in the art will appreciate that the ramp 
contact/latching feature 184 can be incorporated in the flexure at either 
the location shown at 138 in FIG. 1 or at the location shown at 142 in 
FIG. 1-1. The ramp contact/latching feature 184 is shown as an integral 
portion of the flexure (114 in FIG. 1, 140 in FIG. 1-1), and includes a 
beam portion 186 extending laterally from the flexure. At the distal end 
of the beam portion 186, the ramp contact/latching feature 184 is formed 
to provide specific elements critical to the present invention. In 
particular, the ramp contact/latching feature 184 can be seen to include a 
vertical latching face 188 extending downward from the distal end of the 
beam portion 186 and a cylindrical contact element 190 continuing from the 
lowermost end of the vertical latching face 188. The latching face 188 and 
cylindrical contact element 190 interact with certain features and 
elements of the ramp structure (160, 162 in FIG. 3-1 and FIG. 3-2, 
respectively) in a manner to be discussed below to implement the present 
invention. 
FIG. 4-2 shows a second configuration of a ramp contact/latching feature 
184a. This alternative configuration also includes a beam portion 186 
integral to and extending laterally from the head supporting flexure 
114/144 as in FIG. 4-1. The distal end of the beam portion 186 is formed 
into a cylindrical support portion 190a which is used to support a pin 
element 189 which is cantilevered from the support portion 190a. The 
direction in which the pin element extends from the support portion will 
be dependent on the type of flexure/head configuration with which it is 
used, i.e., the configuration of FIG. 1 or the configuration of FIG. 1-1. 
In the alternative configuration of ramp contact/latching feature 184a of 
FIG. 4-2, actual contact between the ramp structure and the flexure will 
occur at the pin element 189, as will be appreciated by one of skill in 
the art. Subsequent discussions of the operation of the present invention 
will be directed to the configuration of ramp contact/latching feature 184 
of FIG. 4-1, but a person of skill in the art will understand that such 
discussions are also applicable to the configuration of ramp 
contact/latching feature 184a of FIG. 4-2. 
Turning now to FIG. 5-1 through FIG. 5-4, shown are simplified elevation 
views of the relevant components of a disc drive that incorporates the 
ramp and latching system of the present invention. FIG. 5-1 through FIG. 
5-4 illustrate, in turn, the component relationships involved in the steps 
of unloading the heads from the discs, latching the actuator, unlatching 
the actuator, and preparing to reload the heads back onto the discs, 
respectively. 
FIG. 5-1 shows a ramp structure 162 similar to that described above in 
relationship to FIG. 3-2, the outermost portions of three discs 106, and 
six heads 112. The five lower heads 112 can be seen to be supported on 
flexures including typical prior art ramp contact features 138 and will 
interact with elements of the ramp structure 162 in the manner described 
above in relationship to FIG. 2-1 through FIG. 2-4. 
The topmost head in the figures is mounted on and supported by a flexure 
which includes the ramp contact/latching feature 184 of FIG. 4-1. FIG. 5-1 
shows the position of components when the actuator has moved the heads 112 
outward (in the direction of arrow 192) and shows that the heads 112 have 
been lifted vertically away from the surfaces of the discs 106 as the ramp 
contact features 138 and ramp contact/latching feature 184 travel in 
contact with the beveled portions of the ramp fingers up to the flat 
portions of the ramp fingers. 
FIG. 5-2 shows that, as the actuator continues to move the heads outward, 
the ramp contact/latching feature 184 reaches the latching face 170 of the 
top ramp finger, and the flexure load pressure causes the ramp 
contact/latching feature 184 to drop down, in the direction of arrow 194, 
into its latched position. In the latched position, the vertical latching 
face (188 in FIG. 4) of the ramp contact/latching feature 184 is in 
contact with the latching face 170 of the top ramp finger, thus 
effectively preventing motion of the actuator back toward the discs 106. 
It should also be noted that the cylindrical contact element (190 in FIG. 
4) of the ramp contact/latching feature 184 rests on the pivoting ramp 
surface 180 of the pivoting member 172, and the beam portion (186 in FIG. 
4) rests on the flat portion (168 in FIG. 3-2) of the top ramp finger. 
Such contacts, however, are not critical to the latching function of the 
present invention, and a person of skill in the art will appreciate that 
the significant latching contact is that between the vertical latching 
faces (188 in FIG. 4, 170 in FIG. 3-2). 
It can also be seen in FIG. 5-2 that any tendency of the pivoting member 
172 to rotate clockwise as a result of contact with the ramp 
contact/latching feature 184 is prevented by contact between the lower 
surface of the pivoting member 172 and a downward contact pin 196 
extending from the top ramp finger in a manner similar to that shown for 
the upward contact pin in the description of FIG. 3-1 and FIG. 3-2 above. 
It should be restated at this point that the latching function of the 
present invention typically operates as a result of the detection of a 
power loss to the disc drive, and, as such, occurs only as a result of the 
actuator being driven outward using the back emf of the spindle motor 
power. Thus the latching operation is totally passive and requires only 
this actuator motion to operate. 
FIG. 5-3 illustrates component motion and relationships which provide the 
unlatching function of the present invention. Since unlatching of the 
actuator will only occur upon restoration of power to the actuator, all 
events described subsequently will be under control of the disc drive 
electronic control circuitry, in manner well known in the industry. 
In disc drives incorporating head ramps, it is common practice to wait 
after application of power until the discs have accelerated to a speed 
sufficient to establish an air bearing for the heads before initiating 
unlatching of the actuator and reloading the heads into their operating 
relationship to the discs. Thus, in disc drives incorporating the present 
invention, once other disc drive actions necessary to overall operations 
have been completed, the internal power up programming of the disc drive 
initiates the unlatch sequence. 
As shown in FIG. 5-3, in the first operation of the unlatching sequence, 
the actuator is driven outward along the pivoting ramp surface 180 in the 
direction of arrow 198. This results in contact between the cylindrical 
contact element 190 of the ramp contact/latching feature 184 and the 
unlatching contact feature 182 of the pivoting member 172. As the actuator 
continues to be driven outward the flexible hinge element 174 is bent and 
the pivoting member is rotated counterclockwise, as shown by arrow 200, 
until contact is made between the upward contact pin and the pivot contact 
feature (176, 178 in FIG. 3-2, respectively). When this limit to rotation 
is reached, the pivoting ramp surface 180 is lifted to a position in which 
it is at an angle slightly above the flat portion 168 of the top ramp 
finger 166. This relationship is shown in detail in FIG. 5-3-1. 
FIG. 5-3-1 shows a portion of the pivoting member 172 in the position to 
which it would be driven for unlatching operation. From the figure, it is 
clear that the pivoting ramp surface 180 is slightly above the flat 
portion 168 of the ramp, and that the amount of non-coplanarity of these 
surfaces is determined by the contact between the upward limit pin 176 and 
the pivot contact feature 178. Bringing the pivoting ramp surface 180 into 
this relationship with the flat portion 168 of the ramp structure is 
necessary because, once the actuator begins to move the heads toward the 
discs, the force applied by the actuator to rotate the pivoting member 172 
(as shown in FIG. 5-3) is removed, and the pivoting member 172 begins to 
return to its rest position under influence of the load force of the 
flexure exerted on the pivoting ramp surface 180 and the stress induced in 
the flexible hinge element 174 during the rotation of the pivoting member 
172. Thus, the extent to which the pivoting ramp surface 180 rises above 
the flat portion 168 will be determined as a function of the material of 
the ramp structure 162, the dimensions of the flexible hinge element 174 
and the load force exerted by the flexure against the pivoting ramp 
surface 180, all selected based on how quickly the actuator can move the 
heads from the unlatch position of FIG. 5-3 to a position wherein the ramp 
contact/latching feature 184 is located inward of the latching face 170 of 
the ramp structure. 
In practice, the rotation of the pivoting member 172 back to its rest 
position (as shown in FIG. 5-1 and FIG. 5-2) is envisioned as a damped 
motion. That is, the entire ramp structure 162 is envisioned as 
manufactured from a plastic or polymer. Such materials are known to be 
relatively slow in returning from a deformed state to an undeformed state. 
Thus, by selection of the material of the ramp structure 162 and selection 
of the dimensions of the flexible hinge element 174, the speed at which 
the pivoting member 172 rotates back to its rest position can be 
determined, and, in the present invention, this rotation speed is 
envisioned to be such that the rotation of the pivoting ramp surface 180 
to a position below the top of the latching face 170 of the ramp structure 
162 will require several milliseconds. The actuator of a typical disc 
drive in which the present invention can be implemented is capable of 
moving the ramp contact/latching feature 184 from the position of FIG. 5-3 
to a position inward of the latching face 170 in approximately two 
milliseconds, including the time to accelerate the actuator and bring it 
to either rest or low velocity with the ramp contact/latching feature 184 
in a position to controllably reload the heads onto the surfaces of the 
discs. 
FIG. 5-4 illustrates the actuator motion that must occur to complete the 
unlatching action of the present invention. In the figure, it can be seen 
that the actuator has driven the heads inward in the direction of arrow 
202 and to a position where the cylindrical contact element 190 rests on 
the flat portion 168 of the ramp structure. Again, this movement must 
occur before the pivoting ramp surface 180 can rotate in the direction of 
arrow 204 to a position below the top of the latching face 170. From the 
actuator position shown in FIG. 5-4, the heads 112 can be moved down the 
beveled portion 154 of the ramps and into their operative relationship 
with the discs 106 in a manner consistent with the prior art. 
Additional optional features of the ramp system are also shown in FIG. 5-1 
through FIG. 5-4. For instance, the figures show head protection surfaces, 
represented by dotted lines designated 206 in FIG. 5-4, extending from the 
lateral surfaces of the ramp fingers between facing pairs of heads 112, as 
was discussed in relationship to the prior art FIG. 2-2 through 2-4. Since 
the pivoting member 172 in FIG. 5-1 through FIG. 5-4 is shown on the near 
side of the ramp fingers, and since it is desirable to have the heads 112 
located in close proximity to the ramp contact features of the flexures, 
the heads 112, as shown in FIG. 5-1 through FIG. 5-4, are on the far side 
of the ramp structure. Such relationships are consistent with flexure 
configurations such as that of FIG. 1-1. 
A ramp structure 208, such as that shown in FIG. 5-1 through FIG. 5-4, 
incorporating the optional head protection surfaces 206 is shown in FIG. 
6-2, while FIG. 6-1 shows a similar ramp structure 210 useful with flexure 
configurations such as that of FIG. 1. 
Further examination of FIG. 6-2 reveals that the rearmost portion of the 
lowermost ramp finger includes a step-down 212 which extends rearward to 
define the lower extent of the backing member 214. Similar step-downs are 
also shown in FIG. 3-1 and FIG. 3-2, FIG. 5-1 through FIG. 5-4 and in FIG. 
6-1. This step-down 212 is included to provide spacing for the lowermost 
head/flexure assembly, and it will be readily recognized that such spacing 
could alternatively be provided by a relief feature in the disc drive 
housing base member. 
It is presently envisioned that the ramp structure of the present invention 
will be mounted in the disc drive by an adhesive applied to the lower 
surface 216 of the backing member and bonding the ramp structure to the 
housing base member. However, one of skill in the art will realize that 
the backing member 214 can be easily modified to incorporate a mounting 
flange which can be attached to the housing base member using machine 
screws or other similar fasteners. 
FIG. 7 shows an alternative embodiment of the ramp/latching system of the 
present invention in which the ramp structure 218 includes the latching 
and unlatching features described on both the top and bottom ramp fingers. 
Such a structure would provide substantially double the latching security 
of the previously described embodiments, should this be desirable in the 
disc drive in which the present invention is incorporated. It will also be 
recognized that the ramp/latching system of the present invention could be 
implemented with the described latching features associated with only the 
lowermost ramp surfaces. 
The person of skill in the art will also realize that the latching 
mechanism of the present invention could also be implemented in disc 
drives of the type wherein the heads are parked on the disc surfaces near 
the inner diameter of the discs. Such a latching system would include a 
latching feature integral to the actuator coil which has vertical 
compliance, a single ramp feature having a vertical latching face and a 
pivoting element similar to that already described to enable unlatching 
under control of actuator movement. 
From the foregoing, it is apparent that the present invention is 
particularly well suited to achieve the objects and provide the benefits 
set forth hereinabove as well as others inherent therein. While particular 
embodiments of the invention have been described herein, modifications to 
the embodiments which fall within the envisioned scope of the invention 
may suggest themselves to one of skill in the art who reads this 
disclosure. Therefore, the scope of the invention should be considered to 
be limited only by the following claims.