The present invention relates to a system of controlling a micro-actuator of an information recording disk drive device. More particularly, the present invention relates to a head gimbal assembly (HGA) with a micro-actuator, a flexible printed cable (FPC) for controlling the micro-actuator, a head stack assembly (HSA) with a plurality of the HGAs and a disk drive unit with the head stack assembly.
Disk drive is an information storage device that uses magnetic media to store data and a movable read/write head that is positioned over the media to selectively read from or write to the media.
Consumers are constantly desiring greater storage capacity for such disk drive devices, as well as faster and more accurate reading and writing operations. Thus, disk drive manufacturers have continued to develop higher capacity disk drives by increasing the recording and reproducing density of the information tracks on the disks. However, each increase in track density requires that the disk drive device have a corresponding increase in the positional control of the read/write head. As track density increases, it becomes more and more difficult to quickly and accurately position the read/write head over the desired information tracks on the disk. Thus, disk drive manufacturers are constantly seeking ways to improve the positional control of the read/write head in order to take advantage of the continual increases in track density.
One common disk drive includes a serve controller driving a voice coil motor (VCM) to position a read/write head over a desired track of a magnetic disk. Referring to
In order to solve the problem, an additional actuator mechanism, for example a piezoelectric (PZT) micro-actuator, is introduced in the head gimbal assembly of the disk drive device in order to modify the displacement of the slider. The piezoelectric micro-actuator could corrects the displacement of the slider on a much smaller scale, as compared to the voice coil motor, in order to compensate for the resonance tolerance of the voice coil motor. Generally, the micro-actuator enables, for example, the use of a smaller recording track pitch, and can increase the “tracks per inch” (TPI) value by 50% for the disk drive unit, as well as provide an advantageous reduction in the head seeking and settling time.
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However, when regarding to the whole structure of the head gimbal assembly 200/300 of the prior technology, it is recognized that the micro-actuator 220/320 and the suspension 230/330 of the head gimbal assembly 200/300 are both complex in structure. That is, the micro-actuator 210/310 forms at least three pads and the suspension 230/330 accordingly needs to provide at least three pads for electrical connection with the micro-actuator 210/310. Moreover, the suspension 230/330 forms two operation channels with two suspension inner traces 233/333 for electrically connecting the micro-actuator 220/320 with the flexible printed cable. Moreover, the dual operation channels for the micro-actuator 220/320 need a complex drive generator for the full hard disk drive (HDD) to provide the sine actuating voltage in opposite phase and also a complex printed circuit board assembly (PCBA) design and manufacture. All of the above-mentioned features lead the head gimbal assembly 200/300 complex in trace and pad layout, more components and its control circuit, which accordingly, not only increase the manufacturing cost but also complicates the fabrication process.
In addition, as in the prior art, the inner traces 233/333 are intermixed among read traces and write traces of the suspension outer traces 232/332, high-voltage signal inputted into the inner traces 233/33 will adversely induce cross-talk between the read traces of the suspension outer traces 232/332 and the inner traces 233/333, which could weaken quality of signal transmitted into the slider 210/310 as well as the micro-actuator 220/320 and accordingly badly affect the operation characteristics of the head gimbal assembly 200/300.
Moreover, as the flexible printed cable need to provide multiple voltage leads to drive or simulate respective two piezoelectric elements of the micro-actuator 220/320, which not only takes large space and makes a bulky size, but also wastes electricity resource.
Finally, once the micro-actuator 220/320 is driven, the PZT elements of the micro-actuator 220/320 will be excited to move and according lead the slider 210/310 to translate. The translation of the slider 210/310 generates a lateral inertia force, and the lateral inertia force will adversely causes a vibration resonance on suspension 230/330, which in turn, drives an off-track motion of the slider 210/310, finally making the head out of TMR (Track Mis-Registration) budget. Moreover, because of the requirement of progressively miniaturized size and large storage capacity, head stack assembly equipped with a plurality of head gimbal assemblies has gained a wide popularity. Because every two head gimbal assemblies are mounted to a common drive arm, and because each head gimbal assembly has provided with a corresponding micro-actuator, thus when operating all these micro-actuators, the micro-actuators in the two head gimbal assemblies will move in the same direction, for example outward or toward their respective disks. The same-direction motion will couple and interact together, thus causing extraordinarily serious vibration on the corresponding drive arm, which further leads the sliders to be off-track and out of TMR budget. This, accordingly, seriously affects the dynamic performance of each head gimbal assembly and limits the servo band width and the capacity improvement of the disk drive.
Hence, a need has arisen for providing a head gimbal assembly, a flexible printed cable, a head stack assembly and a disk drive unit to overcome the above-mentioned disadvantages.
Accordingly, an object of the present invention is to provide a head gimbal assembly with a simple layout of minimum channel and pads.
Another object of the present invention is to provide a head gimbal assembly avoiding the occurrence of cross-talk.
Still another object of the present invention is to provide a flexible printed cable with a simple layout of leads for saving space and reducing size of the flexible printed cable.
Yet another object of the present invention is to provide a head stack assembly which not only possesses a simple layout of minimum channel and pads but also reduces or even prevents suspension vibration resonance and arm vibration resonance as well as avoids sliders in the head stack assembly from off-track and out of TMR budget.
Still another object of the present invention is to provide a disk drive unit with a simple structure and a sound performance.
To achieve above objects, a head gimbal assembly comprises a micro-actuator with two piezoelectric elements of opposite polarization and a suspension. The suspension has a top portion and a tail portion. The micro-actuator is disposed on the top portion. The tail portion has a bonding terminal adapted for establishing electrical connection with a flexible printed cable. The suspension provides a single channel electrically connecting the bonding terminal with the micro-actuator for controlling the movement of the micro-actuator.
As an embodiment of the present invention, the micro-actuator provides only two pads respectively formed on corresponding piezoelectric elements and both electrically connected with the bonding terminal thus forming the single channel.
As another embodiment of the present invention, the micro-actuator provides a ground pad and a signal-input pad respectively formed on corresponding piezoelectric elements, and the bonding terminal provides only one signal-control lead, and the single channel is formed by electrically connecting the signal-control lead of the bonding terminal with the signal-input pad of the micro-actuator.
In the invention, the bonding terminal further provides a slider flying height adjustment lead, a pair of read differential leads and a pair of write differential leads, and the signal-control lead is laminated between the pair of write differential leads.
A head gimbal assembly comprises a slider, a micro-actuator with two piezoelectric elements of opposite polarization, and a suspension. The suspension has a top portion and a tail portion. The slider and the micro-actuator are disposed on the top portion. The tail portion has a bonding terminal adapted for establishing electrical connection with a flexible printed cable. The bonding terminal provides a signal-control lead, a slider flying height adjustment lead, a pair of read differential leads and a pair of write differential leads. The signal-control lead is electrically connected to the micro-actuator. The slider flying height adjustment lead, the pair of read differential leads and the pair of write differential leads are electrically connected to the slider respectively. The signal-control lead is laminated between the pair of write differential leads.
As an embodiment of the present invention, the bonding terminal has three windows. One window accommodates the pair of read differential leads, another window accommodates one of the pair of write differential leads and the slider flying height adjustment lead, and still another window accommodates the other write differential lead and the signal-control lead.
The present invention provides a flexible printed cable adapted for connecting a group of stacked head gimbal assemblies with a control system. Each head gimbal assembly has a micro-actuator. The flexible printed cable comprises a top portion, an end portion opposite the top portion for connecting to the control system, and one common voltage lead for transmitting micro-actuator drive voltage. The top portion has a plurality of connection terminals adapted for connecting to the respective head gimbal assemblies. The connection terminals each have a signal-control pad adapted for establishing electrical connection with the corresponding micro-actuator. All of the signal-control pads of the connection terminals are connected to the common voltage lead.
In embodiments of the invention, each of the connection terminals further has a slider flying height adjustment pad, a pair of read differential pads, and a pair of write differential pads.
Preferably, each of the connection terminals has three windows, one window accommodates the pair of read differential pads, another window accommodates one of the pair of write differential pads and the slider flying height adjustment pad, and still another window accommodates the other write differential pad and the signal-control pad.
A head stack assembly comprises a plurality of drive arms, a group of up-face head gimbal assemblies facing upward, a group of down-face head gimbal assemblies facing downward, and a flexible printed cable for electrically controlling the operation of all the head gimbal assemblies. The up-face and the down-face head gimbal assemblies are connected to the drive arms in such a manner that the up-face head gimbal assemblies and the down-face head gimbal assemblies are alternately arranged and stacked. Each of the head gimbal assembly comprises a slider, a micro-actuator with two piezoelectric elements of opposite polarization, and a suspension having a top portion and a tail portion. The slider and the micro-actuator are disposed on the top portion. The tail portion has a bonding terminal electrically connected with the flexible printed cable. The suspension provides a single channel electrically connecting the bonding terminal with the micro-actuator. The up-face head gimbal assemblies and the down-face head gimbal assemblies have a relation that if align the up-face head gimbal assemblies and the down-face head gimbal assemblies in the same direction, the piezoelectric elements and the channels of all the head gimbal assemblies are same.
A disk drive unit comprises a head stack assembly, a stack of disks, a spindle motor operable to spin the disks. The head stack assembly comprises a plurality of drive arms, a group of up-face head gimbal assemblies facing upward, a group of down-face head gimbal assemblies facing downward, and a flexible printed cable for electrically controlling the operation of all the head gimbal assemblies. The up-face and the down-face head gimbal assemblies are connected to the drive arms in such a manner that the up-face head gimbal assemblies and the down-face head gimbal assemblies are alternately arranged and stacked. Each of the head gimbal assembly comprises a slider, a micro-actuator with two piezoelectric elements of opposite polarization, and a suspension having a top portion and a tail portion. The slider and the micro-actuator are disposed on the top portion. The tail portion has a bonding terminal electrically connected with the flexible printed cable. The suspension provides a single channel electrically connecting the bonding terminal with the micro-actuator. The up-face head gimbal assemblies and the down-face head gimbal assemblies have a relation that if align the up-face head gimbal assemblies and the down-face head gimbal assemblies in the same direction, the piezoelectric elements and the channels of all the head gimbal assemblies are same.
In comparison with the prior art, as the head gimbal assembly employs a single channel to control the movement of the micro-actuator, and the micro-actuator forms only two pads to form the single channel, thus the head gimbal assembly possesses a simple layout. Therefore, the head gimbal assembly has a simple layout of minimum channel and pads.
In addition, the head gimbal assembly of the present invention make the signal-control lead to be laminated between the pair of write differential leads, thus the write differential leads will works as a shield which prevent the signal conducting to the micro-actuator from coupling to the read differential leads, advantageously reducing or preventing cross-talk between the read differential leads and the signal-control lead, therefore operational performance of the head gimbal assembly is optimized.
Moreover, as the flexible printed cable utilizes a common voltage lead to connect all the signal-control pads of the connection terminals for simultaneously transmitting micro-actuator drive voltage, thus the flexible printed cable has a simple layout of leads for saving space, and the size of the flexible printed cable can be reduced.
Finally, as the up-face head gimbal assemblies and the down-face head gimbal assemblies have a relation that if align the up-face head gimbal assemblies and the down-face head gimbal assemblies in the same direction, the piezoelectric elements and the channels of all the head gimbal assemblies are same, thus when operating the micro-actuators of all the head gimbal assemblies, the micro-actuator of each up-face head gimbal assembly will rotate in oppose direction against the micro-actuator of each down-face head gimbal assemblies. Accordingly, the rotation forces in oppose direction cancel each other, which prevents suspension vibration resonance and arm vibration resonance, thus significantly avoiding the sliders from off-track and out of TMR budget.
Other aspects, features, and advantages of this invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate by way of example, principles of this invention.
The accompanying drawings facilitate an understanding of the various embodiments of this invention. In such drawings:
a shows a typical head gimbal assembly with a micro-actuator for precise positional control of the read/write head according to a first conventional prior art;
b shows a tongue region of the head gimbal assembly of
c is a perspective view of the micro-actuator shown in
d shows a detailed process of mounting a slider of the head gimbal assembly to the micro-actuator of
a shows a tongue region of a head gimbal assembly according to a second conventional prior art.
b is a perspective view of a micro-actuator of the head gimbal assembly shown in
c is a circuit diagram generally showing circuit connection relationships within the micro-actuator shown in
a is a perspective view of a micro-actuator of the head gimbal assembly shown in
b is a circuit diagram generally showing circuit connection relationships within the micro-actuator shown in
a is a plan view showing a tail portion of the head gimbal assembly of
b is an enlarged, plan view of a bonding terminal of the tail portion shown in
a is a plan view showing a flexible printed cable according to the present invention;
b is an enlarged, plan view of a top portion of the flexible printed cable of
a is a plan view showing a tail portion of the down-face head gimbal assembly of
b is an enlarged, plan view of a bonding terminal of the tail portion in
a is a plan view showing a tail portion of the up-face head gimbal assembly of
b is an enlarged, plan view of a bonding terminal of the tail portion in
Various preferred embodiments of the invention will now be described with reference to the figures, wherein like reference numerals designate similar parts throughout the various views. The present invention provides a head gimbal assembly with a simple layout of a single channel and only two pads for micro-actuator. Moreover, the present invention provides a head gimbal assembly which could avoid occurrence of cross-talk and a flexible printed cable with a common voltage lead adapted to connect all the signal-control pads which enable to reduce the size of the flexible printed cable. Besides, the present invention employs a head stack assembly with alternately arranged and stacked head gimbal assemblies, which reduces or even prevents suspension vibration resonance and arm vibration resonance as well as avoids all sliders in the head stack assembly from off-track and out of TMR budget.
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a-9b illustrate a flexible printed cable 600 according to the present invention for connecting a group of stacked head gimbal assemblies mentioned above with a control system. The flexible printed cable 600 comprises a top portion 650 having a plurality of connection terminals for connecting to the respective head gimbal assemblies and an end portion 660 opposite the top portion 650 for connecting to the control system. The flexible printed cable 600 further comprises one common voltage lead 680 (referring to
In the subject embodiment, each of the connection terminals has three windows, one window accommodates one read differential pad 651a/651′a and the other read differential pad 651b/651′b, another window accommodates one write differential pads 652a/652′a and the slider flying height adjustment pad 652/652′ and still another window accommodates the other write differential pad 653b/653′b and the signal-control pad 653/653′.
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According to the principle of the present invention, each of the micro-actuators 920/920′ provides two pads respectively formed on corresponding piezoelectric elements and both electrically connected with the corresponding bonding terminal 950/950′ thus forming the corresponding single channel.
In the subject embodiment, the micro-actuator of each of the down-face/up-face head gimbal assemblies 900/900′ provides a ground pad and a signal-input pad. Take the down-face head gimbal assembly for illustrated, referring to
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As illustrated, the flexible printed cable 600 is featured as mentioned above.
The foregoing description of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. Such modifications and variations that may be apparent to those skilled in the art are intended to be included within the scope of this invention as defined by the accompanying claims.