MULTIMODE HARD DISPLAY DRIVE RECIRCULATION FILTER SYSTEM

Abstract

A multimode recirculating filter for a hard disk drive (HDD) includes a housing for filter media with first ribs that have a first spacing between them and extend from one side of the disk towards the filter media, a first air chamber on the opposite side of the filter media behind the first ribs and with a closed back, and a flow path to receive the flow into the air chamber, all of which allows for pressure reduction on the disk side to maximize the pressure drop across the filter, while a head stack assembly (HSA) is placed on a ramp.The housing further includes second ribs downstream of the first ribs, between which there is a second gap that is larger than the first gap, and a second air chamber behind the second ribs and with an open back, all of which allows for increased pressure on the disk side in conjunction with the pressure generated by the HSA while it is loaded on a disk stack.

Description

AREA OF EXECUTION FORMS

[0001] Embodiments of the invention may relate generally to hard disk drives and in particular to approaches for a recirculating filter system designed for effectiveness and efficiency across the entire operating range of a head stack assembly (HSA). BACKGROUND

[0002] A hard disk drive (HDD) is a non-volatile storage device housed in a protective enclosure that stores digitally encoded data on one or more circular platters with magnetic surfaces. When an HDD is operating, each magnetic recording platter is rapidly spun by a spindle system. Data is read from and written to a magnetic recording platter using a read / write head (also called a "transducer") housed in a slider, which is positioned over a specific location on a platter by an actuator. A read / write head uses magnetic fields to write data and to read data from the surface of a magnetic recording platter. A write head uses the flow of electricity through its coil to generate a magnetic field. Electrical pulses are sent to the write head with different patterns of positive and negative currents.The current in the coil of the write head generates a localized magnetic field through the gap between the head and the magnetic recording disc, which in turn magnetizes a small area on the recording medium.

[0003] Because the platters inside a hard disk drive (HDD) rotate during operation, a gas flow (air, helium, etc.) is generated. In fact, the air-bearing glider (or gas-bearing glider in general), on which a read / write head is mounted, relies on this gas flow to move across the platter and function as intended. However, small particles of airborne dust can adhere to the air-bearing surfaces of a read / write head or settle on the surface of a platter. If a dust particle becomes lodged on the surface of a read / write head or a platter, the head may not read the data correctly or may scratch the surface of a platter, potentially abrading the thin magnetic film of the platter. This can lead to data loss and possibly render the HDD unusable.During the manufacturing process, airborne dust particles can enter the HDD enclosure. Additionally, during operation, certain internal components can come into contact with each other in a way that releases airborne dust particles. To remove airborne dust particles from inside an HDD, an airflow filter (also known as a "recirculating filter") and a "vent filter" can be installed inside the enclosure to equalize pressure between the inside and outside of the enclosure. These filters are typically located in a stream of air created by the rotation of the platters. As the gas flows through these filters, the particles carried in the gas are trapped, thus cleaning the air.As the amount of gas flowing through a particulate filter increases, so does the number of particulate matter captured by the filter. However, using gases lighter than air inside a hard disk drive (HDD) can negatively impact filter performance because these types of filters operate at a lower pressure differential.

[0004] All approaches that can be described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise stated, it should not be assumed that any of the approaches described in this section qualify as prior art simply because it is included here. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Embodiments are illustrated by way of example and without limitation in the figures of the accompanying drawings, in which the same reference numerals are used to denote similar elements: Fig. Figure 1 is a top view illustrating a hard disk drive (HDD) according to one embodiment; Fig. 2A is a top view showing a spoiler with an HDD; Fig. 2B is a perspective view that shows the spoiler of Fig. 2A illustrates; Fig. 3A is a perspective exploded view illustrating a return flow recirculation filter for an HDD according to one embodiment; Fig. 3B is a perspective view showing the installed backflow recirculation filter of Fig. 3A illustrated according to one embodiment; Fig. Figure 4 is a top-view pressure diagram illustrating a 7-cavity aspect ratio for a reflux recirculation filter according to one embodiment; Fig. 5A is a perspective exploded view illustrating a multimode recirculating filter for an HDD according to one embodiment; Fig. 5B is a perspective view showing the installed multimode recirculation filter of Fig. 5A illustrated according to one embodiment; Fig. Figure 6A is a top view illustrating the functionality of a multimode recirculating filter with a head stack assembly (HSA) placed on the loading / unloading ramp according to one embodiment; Fig. Figure 6B is a top view showing the functionality of the multimode recirculating filter of Fig. 6A illustrated with HSA loaded on the plate according to one embodiment; Fig. Figure 7A is a perspective view illustrating a multimode recirculating filter according to one embodiment; Fig. 7B is a front view showing the multimode recirculating filter of Fig. 7A illustrated according to one embodiment; Fig. 7C is a top view showing the multimode recirculating filter of Fig. 7A illustrated according to one embodiment; Fig. 7D is a side view showing the multimode recirculation filter of Fig. 7A illustrated according to one embodiment; Fig. 7E is a sub-view showing the multimode recirculation filter of Fig. 7A illustrated according to one embodiment; Fig. 7F is a cross-sectional view AA showing the multimode recirculating filter of Fig. 7A illustrated according to one embodiment; and Fig. 7G is a cross-sectional view BB, showing the multimode recirculation filter of Fig. 7A illustrates one embodiment. DETAILED DESCRIPTION

[0006] In general, approaches for a recirculating filter system for hard disk drives (HDDs) are described, designed for operation across the operating range of the head stack assembly (HSA). For explanatory purposes, numerous specific details are presented in the following description to provide a thorough understanding of the embodiments of the invention described herein. However, it will be evident that the embodiments of the invention described herein can be implemented without these specific details. In other cases, known structures and devices may be shown in block diagram form to avoid making the embodiments of the invention described herein unnecessarily unclear. Introduction Terminology

[0007] References herein to “an embodiment” and the like are intended to mean that the particular feature, structure, or characteristic is included in at least one embodiment of the invention. However, the occurrence of such expressions does not necessarily refer to the same embodiment.

[0008] The term "essentially" is to be understood as describing a feature that is largely or almost fully structured, set up, dimensioned, etc., but where, in practice, manufacturing tolerances and the like may lead to a situation in which the structure, setup, dimension, etc., is not always or necessarily exactly as specified. For example, describing a structure as "essentially vertical" would give this term its obvious meaning, such that the structure is vertical for all practical purposes, but may not be exactly at 90 degrees everywhere.

[0009] Even though terms such as "optimal," "optimize," "minimal," "minimize," "maximize," "maximize," and the like may not be associated with specific values, the intention hereof is that the person skilled in the art would understand such terms to refer to a value, parameter, metric, and the like in a beneficial direction consistent with the whole of this disclosure. For example, describing a value of something as "minimal" does not require that the value actually be equal to a theoretical minimum (e.g., zero), but should be understood in a practical sense as meaning that a corresponding objective would be to move the value in a beneficial direction toward a theoretical minimum. context

[0010] It is important to consider that conventional recirculating filter designs for hard disk drives (HDDs) rely on generating a pressure differential across a filter. HDDs filled with helium or another gas lighter than air present a particular challenge compared to air-filled drives because the flow characteristics of helium, with its lower density, result in a kinematic viscosity more than seven times higher. To generate effective pressure across filter media for HDD cleaning, some filter systems incorporate ribs that extend into the airflow between the rotating platters. These ribs provide an effective barrier that redirects particle movement through the filter media. Such ribs can be integrated upstream of a head stack assembly (HSA) spoiler, which may include an opening for a particulate air filter. Fig. Figure 2A is a top view illustrating a hard disk drive (HDD) with a spoiler. The HDD 200 has a spoiler 202 installed in a chassis base 204. Fig. 2B is a perspective view that shows the spoiler of Fig. Figure 2A illustrates this. This view shows the shape of an upper rib 202t of the spoiler 202 as well as the shapes of several middle ribs 202m of the spoiler 202, which are arranged between adjacent plates of a plate stack (removed here for clarity). Fig. Figure 2B further illustrates the presence of a filter pocket 202p of the spoiler 202, which is set up to accommodate a suspended dust particle filter (not shown).

[0011] When a pre-spoiler redirects the gas flow from the head slider, the spoiler creates a region of relatively higher pressure within the gas flow upstream of the spoiler. Gas in this higher-pressure region flows through the particulate filter into a region of relatively lower pressure, thus removing particulate matter from the flow within the HDD enclosure. Attempting to eliminate particulate matter using this approach introduces two significant undesirable effects. The first is that the ribs between the platters create unwanted air resistance, increasing the power consumption of the spindle motor. The second is that this approach to redirecting the particles is not entirely effective in forcing them to be captured by the filter media.Experiments on particle accumulation and CFD (computational fluid dynamics) analyses have shown that particles accumulate on the plate under the ribs at a rate that is disproportionate to other observed particle deposits on the rest of the plate. Backflow recirculation filter

[0012] Fig. 3A is a perspective exploded view showing a return flow recirculation filter for an HDD, and Fig. 3B is a perspective view showing the installed backflow recirculation filter of Fig. 3A represents both according to one or more embodiments. Fig. Figures 3A to 3B illustrate a return flow recirculation filter relative to a conventional hard disk drive (HDD) 100, which has disk media mounted on a spindle (not shown here; see, for example, recording medium 120 of Fig. 1) a head glider that accommodates a read / write converter (not shown here; see e.g. glider 110b, which accommodates a magnetic read / write head 110a of Fig. 1 including), which is configured for reading from and writing to a disk medium of the disk media, an actuating assembly (not shown here; see e.g. voice coil 140 of the voice coil motor of Fig. 1), which is used to move the head slider around a pivot point (see also, for example, rotary shaft 148 with an intermediate rotary bearing assembly 152 of Fig. 1) is set up to access parts of the disk medium. These HDD components are housed in an enclosure including a socket (not shown here; see, for example, HDD Enclosure 168 from [reference missing]). Fig. 1).

[0013] According to one embodiment, a recirculation filter 300 (or simply “filter 300”) is installed upstream (e.g. at a location designated as “7 o’clock”, and with regard to the direction 172 of Fig. The recirculating filter 300 is positioned next to the rotating medium(s) 120 and adjacent to the rotating shaft 148 / bearing assembly 152 (simply referred to as the "pivot point"). The recirculating filter 300 has a housing 302 configured to accommodate filter media 304, the housing 302 having a set of ribs 302a with a first spacing between them, extending from a side of the housing 302 facing the plate towards the filter media 304. The recirculating filter 300 further has an air chamber 306 with a closed rear side on a side opposite the filter media 304 behind the set of ribs 302a. According to one embodiment, the HDD housing 168 includes a disk cover 168a that surrounds a large part of the circumference of a disk stack, including the filter 300 upstream, wherein the disk cover 168a includes a deflection section 168b that is configured to direct the gas flow into the air chamber 306 of the filter 300.In this approach, the flow arriving from the plate stack is redirected through the deflection section 168b of the plate cover 168a behind the filter media 304 and via a supply flow path of the filter 300 into the closed air chamber 306. The geometry of the filter housing 302 is designed such that the pressure on the plate side of the filter media 304 is reduced relative to the side of the air chamber 306, thereby drawing free particles into the filter media 304 (e.g., mainly to the back of the filter media 304). In general, and as shown in the... Fig. As shown in Figures 3A to 3B, each set of ribs 302a of the housing 302 has a substantially flat outermost surface facing the plate, and the set of ribs 302a is provided with a radius of curvature that substantially corresponds to a radius of curvature of the plate media.

[0014] An HDD, such as the HDD 100, still features a head stack assembly (HSA) (see, for example, HSA of Fig. 1) which is coupled to the actuating assembly and houses the head slider. According to one embodiment, the set of ribs 302a of the housing 302 is arranged relative to the filter media 304 to reduce the pressure on the side of the filter 300 facing the plate, while the HSA is on a loading / unloading ramp (not shown here; see, for example, loading / unloading ramp 190 of Fig. 1) is discontinued. A notable aspect of this approach that makes it effective is the vertical rib geometry on the front of the filter, i.e., the set of ribs 302a. The rib orientation (orthogonal to the fluid flow), height, and spacing utilize a phenomenon known as "lid-driven cavity flow" to reduce the pressure on the plate side. This reduction maximizes the pressure drop across the filter 300, which is a primary objective of maximizing fluid and particle flow through the filter media 304.

[0015] In a classic lid-driven cavity flow, the goal is to maintain a constant pressure across the cavity, which here is formed by the set of ribs 302a in conjunction with the filter media 304. This is typically achieved by a wall-to-bottom ratio of one (1). In the case of the filter 300, the cavity floor (filter media 304) and the walls (set of ribs 302a of the housing 302) are likely not exactly perpendicular. Therefore, the goal of CFD (computational fluid dynamics) is to optimize the design so that pressure fluctuations across the bottom are minimal, but not so small as to reduce the effective filter area. Tests and correlated results from CFD analyses have shown that an effective wall-to-bottom design ratio should be in the range of 1 / 4 to 1.According to one embodiment, the set of ribs 302a of the housing 302 is thus arranged such that the ratio of a distance between each rib of the set of ribs 302a relative to a depth of these ribs 302a is in a range of one (1) to four (4).

[0016] Fig. Figure 4 is a top-view pressure diagram illustrating a 7-cavity aspect ratio for a reflux recirculation filter according to one embodiment. While the number of cavities and corresponding ribs may vary from implementation to implementation, in this non-restrictive example, and considering the spatial and other limitations associated with installing such a recirculation filter 300 at the 7 o'clock position within an HDD directly upstream of the pivot point, a 7-cavity arrangement (e.g., a floor-to-wall ratio of approximately 1:1) is considered suitable for the intended purpose. Alternative arrangements with 6 to 4 cavities would likely achieve a floor-to-wall ratio of approximately 4:1 and are considered suitable for the intended purpose.Here is an example of the effect of the ribs 402a (7 ribs in this example) of a housing on the pressure difference across an air chamber 406 (see also e.g. air chamber 306 of the . Fig. 3A to 3B) with a back panel 402b illustrated, behind the filter media (not shown here; see e.g. filter media 304 of Fig. 3A to 3B). A CFD analysis of this model shows that the pressure of the flow entering the air chamber 406 through a supply flow path 402c is approximately 21 Pa (Pascals), and the flow on the other side of the air chamber 406 (e.g., directly inside the ribs 402a) is approximately 12 Pa, thus indicating that a pressure difference of approximately 9 Pa is achievable at the location where the filter media would be housed in this arrangement. This arrangement with inward filter flow (backflow) relies on the secondary flow, which naturally pulls towards the center of rotation (i.e., the spindle motor hub), and on the immediate proximity of the rear wall 402b to the filter media to prevent flow expansion that would otherwise lead to a lower pressure difference across the filter media.

[0017] As described elsewhere herein, previous recirculating cleaning approaches typically require the addition of obstructive features such as spoilers / ribs / wings to redirect the flow, resulting in greater frictional resistance on the plate stack and requiring higher power consumption to maintain motor speed (revolutions per minute). The recirculating filter approach illustrated and described herein effectively eliminates such resistance-inducing features, and simulations and analyses have shown a reduction in power consumption of approximately 7 to 10% relative to that of the previous approach. Fig. The filtration approach illustrated and described in Figures 2A to 2B results in the following outcomes. Furthermore, these same characteristics can also lead to particle deposits on the plate surface, and this reflux filter approach completely eliminates this risk. Multimode recirculation filter

[0018] According to one embodiment, a recirculating filter combines the most effective features of the backflow concept and the spoiler concept in a complementary system that produces effective cleaning times and high filter efficiency when the HSA is on the ramp (e.g., a first mode) and over the HSA stroke from an outside diameter (OD) to an inside diameter (ID) (e.g., a second mode). Fig. 5A is a perspective exploded view illustrating a multimode recirculating filter for an HDD, and Fig. 5B is a perspective view showing the installed multimode recirculation filter of Fig. 5A illustrates both according to one or more embodiments. Fig. Figures 5A to 5B illustrate a multimode recirculating filter relative to a conventional hard disk drive (HDD) 100, which has disk media mounted on a spindle (not shown here; see, for example, recording medium 120 of Fig. 1) a head glider that accommodates a read / write converter (not shown here; see e.g. glider 110b, which accommodates a magnetic read / write head 110a of Fig. 1 including), which is configured for reading from and writing to a disk medium of the disk media, an actuating assembly (not shown here; see e.g. voice coil 140 of the voice coil motor of Fig. 1), which is used to move the head slider around a pivot point (see also, for example, rotary shaft 148 with an intermediate rotary bearing assembly 152 of Fig. 1) is set up to access parts of the disk medium. These HDD components are housed in an enclosure including a socket (not shown here; see, for example, HDD Enclosure 168 from [reference missing]). Fig. 1).

[0019] According to one embodiment, a recirculation filter 500 (or simply “filter 500”) is positioned upstream (e.g., at the “7 o’clock” position) and next to the pivot point, wherein the recirculation filter 500 has a housing 502 configured to accommodate filter media 504, the housing 502 having a first section (e.g., “reflux section”) having a first plurality of ribs 502a with a first spacing between them and extending from a side of the housing 502 facing the plate toward the filter media 504, and a first section 506a (e.g., “reflux section”) of an air chamber, including a closed rear, on a side opposite the filter media 504 behind the first plurality of ribs 502a.According to one embodiment, the housing 168 includes a plate cover 168a upstream of the recirculating filter, the plate cover 168a enclosing a deflection section 168b configured to direct the gas flow into the first section 506a of the air chamber of the recirculating filter 500. In this approach, the incoming flow is diverted from the plate stack, through the deflection section 168b of the plate cover 168a behind the filter media 504, and into the closed (or “semi-closed,” since it is open to the second section 506b) first section 506a of the air chamber at relatively high pressure. The geometry of the filter housing 502 is designed such that the pressure on the plate side of the filter media 504 is reduced relative to the first section 506a of the air chamber side, thereby diverting free particles into the filter media 504 (e.g., in the region of the first plurality of ribs 502a) at least in the area of ​​the first plurality of ribs 502a.mainly on the back of the filter media 504). Generally and as in the . Fig. As shown in Figures 5A to 5B, each of the first plurality of ribs 502a of the first section of the housing 502 has a substantially planar outermost surface facing the plate, and the first plurality of ribs 502a is provided with a radius of curvature that substantially corresponds to the radius of curvature of the plate media.

[0020] As with the 300 circulation filter from Fig. As illustrated and described in Figures 3A to 3B, an HDD such as the HDD 100 further comprises an HSA coupled to the actuating assembly and housing the head slider. According to one embodiment, the first plurality of ribs 502a of the return section of the housing 502 is arranged relative to the filter media 504 to reduce the pressure on the side of the filter 500 facing the disk, while the HSA is located on a load / unload ramp (LUL ramp) (not shown here; see, for example, load / unload ramp 190 of [reference missing]). Fig. 1) is switched off. Here too, the vertical rib geometry on the front of the filter, i.e., the first plurality of ribs 502a, whose orientation (orthogonal to the fluid flow), height, and spacing exploit the lid-driven cavity flow phenomenon, causes a pressure reduction on the plate side. This reduction maximizes the pressure drop across the filter 500, mainly across the return section, which features the first plurality of ribs 502a in conjunction with the closed back wall of the first section 506a of the air chamber. This is a primary objective of maximizing the fluid and particle flow through the filter media 504 while the HSA is switched off on the LUL ramp.

[0021] Here too, in the case of filter 500, the cavity floor (filter media 504) and the walls (first plurality of ribs 502a of the housing 502) are likely not exactly perpendicular. Therefore, the goal of CFD is to optimize the design so that the pressure fluctuations across the floor are minimal, but not so small as to reduce the effective filter area. According to one embodiment, the first plurality of ribs 502a of the first section of the housing 502 is arranged such that the ratio of the spacing between each rib of the first plurality of ribs 502a relative to the depth of these ribs 502a is in the range of one (1) to four (4).

[0022] According to one embodiment, the housing 502 of the filter 500 further comprises a second section located downstream of the first section and thus closer to the pivot point. The second section has a second plurality of ribs 502b with a second spacing between them that is greater than the first spacing between the first plurality of ribs 502a and the spacing extending from the side of the housing 502 facing the plate towards the filter media 504. It should be noted that the first plurality of ribs 502a and the second plurality of ribs 502b may include a common rib, as shown in Fig. 5B is shown. It should also be noted that the second set of ribs 502b includes the most downstream and / or terminal structure, which is located in the Fig. Figures 5A to 5B show a structure that, in appearance, could also be considered a housing "wall," but for the purposes of this description, it is referred to as a "rib" due to its function. While the second set of ribs 502b is shown here with only two ribs, it should be noted that the number of cavities and corresponding ribs of the second set of ribs 502b may vary from implementation to implementation, as one or more additional ribs may be required for reasons of structural stiffness, containment of the filter media 504, ease of manufacture, and the like.

[0023] According to one embodiment, the second section of the recirculation filter 500 further comprises a second section 506b of the air chamber, including an open rear side, on the opposite side of the filter media 504 behind the second plurality of ribs 502b. According to another embodiment, the second section of the housing 502 is configured to allow increased pressure on the plate-facing side of the recirculation filter 500 in conjunction with the stagnation pressure generated by the HSA arms while they are loaded onto the plate media. In this multimode approach, which in operation / functionality corresponds to the previously mentioned spoiler approach of the spoiler 202, Fig. Similar to 2A to 2B, the pressure on the plate side is increased as the HSA moves from the OD to the ID because the arms of the HSA effectively build up a high pressure that forces particles from the plate to / through the filter media 504, and the absence of a complete rear wall (e.g., a rear-opening air chamber) allows the flow to push outwards from the plate stack and expand into the cavity of the voice coil motor (VCM).

[0024] In a multimode recirculating filter like Filter 500, it is likely that particles will be captured on both sides of the filter media 504. This is because at times (i.e., when the HSA is in one mode on the ramp), the first downstream fraction is operationally predominant, as most of the flow through the filter media 504 is from back (air chamber) to front (plate), and the influence of the HSA is less pronounced. Conversely, at other times (i.e., when the HSA is loaded onto the plate stack in another mode), the second downstream fraction is operationally predominant, as most of the flow through the filter media 504 is from front to back, and the influence of the HSA is greater.

[0025] However, a potential disadvantage of using the first and second sets of ribs 502a, 502b for the purposes described herein is the reduction of the effective filter area due to the presence of vertical ribs that block the incoming flow on the side facing the plate. One approach involves minimizing the width of such ribs (e.g., within the limits of manufacturing capabilities and tolerances) and / or maximizing the spacing and thus the open area between adjacent ribs (e.g., "windows"), corresponding to the second section of the filter 500.

[0026] Fig. Figure 6A is a top view illustrating the functionality of a multimode recirculating filter with a head stack assembly (HSA) placed on the loading / unloading ramp according to one embodiment. As with Filter 500 ( Fig. 5A to 5B) according to one embodiment, a recirculation filter 600 (or simply “filter 600”) is positioned upstream (e.g., at the “7 o’clock” position) and next to the pivot point, wherein the recirculation filter 600 has a housing 602 configured to accommodate filter media 604. The housing 602 has a first section (e.g., “return section”) comprising a first plurality of ribs 602a with a first spacing between them, extending from a side of the housing 602 facing the plate toward the filter media 604, and a first section 606a (e.g., “return section”) of an air chamber, including a closed back 602c, on a side opposite the filter media 604 downstream of the first plurality of ribs 602a. According to one embodiment, the filter 600 further comprises a supply flow path 605 (e.g.,an inlet, a scoop) which is designed to receive a gas stream that is directed into the first section 606a of the air chamber of the recirculating filter 600. In this approach, the counterflow from the plate stack is directed under relatively high pressure behind the filter media 604 and into the closed (or “semi-closed”, since it is open to the second section 606b) first section 606a of the air chamber.

[0027] Here too, the geometry of the filter housing 602, i.e., the geometry of the first plurality of ribs 602a on the front of the filter housing 602 relative to the filter media 604, is designed to exploit the lid-driven cavity flow phenomenon to effect a pressure reduction on the plate side of the filter media 604 relative to the first section 606a of the air chamber side of the filter 600, mainly while the HSA is on an LUL ramp (not shown here; see, e.g., loading / unloading ramp 190 of Fig. 1) is switched off. Thus, free particles are drawn into the filter media 604, e.g., mainly to the back side of the filter media 604 from the first section 606a of the air chamber, as illustrated by a flow arrow 608. The flow arrow 608 generally represents the operation / functionality of the return section of the filter 600, as described in more detail with respect to filter 500. According to one embodiment, the first plurality of ribs 602a of the first section of the housing 602 is arranged such that the ratio of a distance between each rib of the first plurality of ribs 602a relative to a depth of these ribs 602a is in a range of one (1) to four (4).

[0028] Fig. Figure 6B is a top view showing the functionality of the multimode recirculating filter of Fig. Figure 6A illustrates HSA loaded on the plate according to one embodiment. According to one embodiment, the housing 602 of the filter 600 further comprises a second section downstream of the first section and thus closer to the rotating shaft 148 / bearing assembly 152. The second section has a second plurality of ribs 602b with a second spacing between them that is larger than the first spacing between the first plurality of ribs 602a, and which extend from the side of the housing 602 facing the plate towards the filter media 604. It should be noted that the first plurality of ribs 602a and the second plurality of ribs 602b may include a common rib. It should also be noted that the second plurality of ribs 602b includes the most downstream and / or final structure, which is located in the Fig. Figures 6A to 6B show a structure that, in appearance, could also be considered a housing "wall," but for the purposes of this description, it is referred to as a "rib" due to its function. While the second set of ribs 602b is shown here with only two ribs, it should be noted that the number of cavities and corresponding ribs of the second set of ribs 602b may vary from implementation to implementation, as one or more additional ribs may be required for reasons of structural stiffness, containment of the filter media 604, ease of manufacture, and the like.According to one embodiment, the second section of the recirculating filter 600 further comprises a second section 606b of the air chamber including an open back on the opposite side of the filter media 604 behind the second plurality of ribs 602b, wherein the air chamber with the open back allows the flow to push outwards from the plate stack and expand into the VCM cavity.

[0029] Here too, the second section of the housing 602 is configured to allow increased pressure on the plate-facing side of the recirculating filter 600 in conjunction with the back pressure generated by the arms of the HSA 620 while they are loaded onto the plate medium(s) 120, as illustrated by a flow arrow 609. The flow arrow 609 generally represents the operation / functionality of this second (e.g., spoiler) section of the filter 600, which utilizes the back pressure generated by the HSA. With this spoiler section of the multimode approach, the pressure on the plate side is increased as the HSA moves from the OD to the ID, because the arms of the HSA 620 effectively build up a high pressure that forces particles from the plate stack through the filter media 604 and into the VCM cavity to the filter media 604.

[0030] Fig. Figure 7A is a perspective view illustrating a multimode recirculating air filter. Fig. 7B is a front view showing the multimode recirculating filter of Fig. 7A illustrates, Fig. 7C is a top view showing the multimode recirculating filter of Fig. 7A illustrates, Fig. 7D is a side view showing the multimode recirculation filter of Fig. 7A illustrates, and Fig. 7E is a sub-view showing the multimode recirculation filter of Fig. Figure 7A illustrates everything according to one or more embodiments. The Multimode Recirculating Filter 700 (or simply "Filter 700") is shown in the detailed views of Fig. 7A to 7G are shown to provide better and more precise visual clarity, and are set up somewhat differently (e.g. fewer ribs 702a) than the 500 filter. Fig. 5A to 5B. However, the description for filter 500 is still largely applicable to filter 700.

[0031] The recirculation filter 700 is installed upstream for positioning (e.g. at the "7 o'clock" position) and is positioned next to the pivot point (see e.g. rotary shaft 148 / bearing assembly 152 of Fig. 1) According to one embodiment, the filter 700 has a housing 702 for accommodating filter media (not shown here for clarity; see, e.g., filter media 504 of Fig. 5A to 5B), wherein the housing 702 has a first section (e.g., "return section") comprising a first plurality of ribs 702a with a first spacing between them, extending from a side of the housing 702 facing the plate toward a filter media cavity 703 (or simply "filter cavity 703"), and a first section 706a (e.g., "return section") of an air chamber, including a closed rear, on a opposite side of the filter cavity 703 downstream of the first plurality of ribs 702a. According to one embodiment, the filter 700 further comprises a supply flow path 705 (e.g., an inlet, a vane) configured to receive a gas flow that is directed into the first section 706a of the air chamber of the recirculating filter 700. For example, a suitable HDD enclosure (see e.g. enclosure 168 from Fig. 1) a panel cover (see e.g. panel cover 168a of Fig. 5A to 5B) upstream of an installed circulation filter 700, wherein the plate cover 168a includes a deflection section (see, for example, deflection section 168b of Fig. 5A to 5B), which is configured to direct the gas flow into the first section 706a of the air chamber of the recirculating filter 700. In this approach, the counterflow is diverted from the plate stack, behind the filter cavity 703, and into the closed (or “semi-closed,” since it is open to the second section 706b) first section 706a of the air chamber under relatively high pressure. The geometry of the filter housing 702 is designed such that the pressure on the disc side of the filter media is reduced relative to the first section 706a of the air chamber side, thereby drawing free particles into the filter media (e.g., mainly to the back side of the filter media) at least in the region of the first plurality of ribs 702a.In general and as shown in one embodiment, each of the first plurality of ribs 702a of the first section of the housing 702 has a substantially flat outermost surface facing the plate, and the first plurality of ribs 702a is provided with a radius of curvature that substantially corresponds to the radius of curvature of the plate media.

[0032] According to one embodiment, the housing 702 of the filter 700 further comprises a second section located downstream of the first section and thus closer to the pivot point. The second section has a second plurality of ribs 702b, which have a second spacing between them that is greater than the first spacing between the first plurality of ribs 702a, and which extend from the side of the housing 702 facing the plate towards the filter cavity 703. It should also be noted that the first plurality of ribs 702a and the second plurality of ribs 702b can include a common rib, as illustrated. It should also be noted that the second plurality of ribs 702b includes the most downstream and / or final structure, which is located in the Fig. Figures 7A to 7E show a second plurality of ribs 702b, which can also be considered a housing “wall” in appearance, but is referred to as a “rib” for the purposes of this description due to its function. While the second plurality of ribs 702b is shown here with only two ribs, it should be noted that the number of cavities and corresponding ribs of the second plurality of ribs 702b may vary from implementation to implementation, as one or more additional rib(s) may be required for reasons of structural rigidity, containment of the filter media, ease of manufacture, and the like. According to one embodiment, the second section of the recirculating filter 700 further comprises a second section 706b of the air chamber, including an open rear, on the opposite side of the filter cavity 703 behind the second plurality of ribs 702b.According to one embodiment, the second section of the housing 702 is configured to allow increased pressure on the disk-facing side of the recirculating filter 700 in conjunction with the pressure generated by corresponding HSA arms of an HDD while they are loaded onto the disk media. In this multimode approach, the disk-side pressure increases as the HSA moves from the OD to the ID, since the HSA arms effectively build up high pressure, forcing the particles from the disk side to / through the filter media. Furthermore, the absence of a complete rear wall (e.g., a rear-opening air chamber) allows the flow to push outward from the disk stack and expand into a VCM cavity of the corresponding HDD.

[0033] Fig. 7F is a cross-sectional view AA showing the multimode recirculating filter of Fig. 7A is illustrated according to one embodiment. With reference to section AA of Fig. Figure 7C further illustrates the cross-sectional view AA, which is configured to receive a gas flow directed into the air chamber of the recirculating filter 700, as by means of a corresponding upstream deflection section 168b of a plate cover 168a of an HDD in which a filter such as filter 700 is to be installed. As described, the counterflow is diverted from the plate stack behind the filter cavity 703 and into the first section 706a of the air chamber.

[0034] Fig. 7G is a cross-sectional view BB, showing the multimode recirculation filter of Fig. 7A illustrates one embodiment. With reference to section BB of Fig. Figure 7D further illustrates the cross-sectional view BB, showing the flow path 705 into the rear-closed first section 706a of the air chamber, which is supported by the rear wall 702c. This view further illustrates the second section 706b of the air chamber, including an open rear section that opens to a VCM cavity (see, for example, the Fig. 6A to 6B), in which a filter such as Filter 700 is to be installed.

[0035] Techniques for improving gas filtration in a hard disk drive (HDD) are described, which are achieved at least in part by creating a pressure differential across a filter medium. This causes gas at the relatively higher pressure area to flow through particle filter media into a relatively lower pressure area, thereby removing airborne dust particles from the stream within the HDD enclosure. Furthermore, a single multimode recirculating filter unit, such as the one illustrated and described herein, e.g., Filter 600 ( Fig. 6A to 6B), Filter 700 ( Fig. 7A to 7E), the phenomenon of lid-driven cavity flow to cause a pressure reduction on the disk side, primarily while the HSA is parked on the loading / unloading ramp (e.g., one mode), and relies on the immediate proximity to the pressure generated by the HSA arms to cause a pressure increase on the disk side, primarily while the HSA is loading onto a disk stack (e.g., another mode). Such a recirculating filter is thus effective at forcing airborne dust particles to filter media in order to capture these particles across the entire operating range of an HDD in general and the HSA in particular. Physical description of an illustrative operational context

[0036] These embodiments can be used in conjunction with a digital data storage device (DSD), such as a hard disk drive (HDD). Thus, according to one embodiment, in Fig. Figure 1 shows a top view illustrating a conventional HDD 100 to aid in describing the usual operation of an HDD.

[0037] Fig. Figure 1 illustrates the functional arrangement of components of the HDD 100, including a slider 110b enclosing a magnetic read / write head 110a. Collectively, the slider 110b and the head 110a can be referred to as the head slider. The HDD 100 includes at least one gimbal head assembly (HGA) 110, which includes the head slider, a guide suspension 110c typically attached to the head slider by a bend, and a load beam 110d attached to the guide suspension 110c. The HDD 100 also includes at least one recording medium 120 rotatably mounted on a spindle 124 and a drive motor (not shown) attached to the spindle 124 to rotate the medium 120. The read / write head 110a, which can also be referred to as a converter, includes a write element and a read element for writing and reading information stored on the medium 120 of the HDD 100.The medium 120 or a variety of plate media can be attached to the spindle 124 using a plate clamp 128.

[0038] The HDD 100 further includes an arm 132 attached to the HGA 110, a carriage 134, a voice coil motor (VCM) comprising an armature 136 including a voice coil 140 attached to the carriage 134, and a stator 144 including a voice coil magnet (not shown). The armature 136 of the VCM is attached to the carriage 134 and configured to move the arm 132 and the HGA 110 to access sections of the medium 120, all of which are mounted together on a rotary shaft 148 with an intermediate rotary bearing assembly 152. In the case of a multi-platter HDD, the carriage 134 can be referred to as an "E-block" and / or a comb, since the carriage is arranged to support a coupled series of arms, giving it the appearance of a comb.

[0039] An assembly comprising a gimbal head assembly (e.g., HGA 110) including a bend to which the head slider is coupled, an actuating arm (e.g., the arm 132) and / or load beam to which the bend is coupled, and an actuating element (e.g., VCM) to which the actuating arm is coupled, can be collectively referred to as a head stack assembly (HSA). However, an HSA may include more or fewer components than those described. For example, an HSA may refer to an assembly that also includes electrical connection components. In general, an HSA is the assembly configured to move the head slider to access sections of the medium 120 for read and write operations.The HSA is designed to mechanically interact with a loading / unloading ramp (LUL ramp) 190 to move the head stack assembly (HSA), including read / write head sliders, away from and off the plates and to position it securely on the support structure of the LUL ramp.

[0040] With further reference to Fig. 1. Electrical signals (e.g., current to the voice coil 140 of the VCM), comprising a write signal to and a read signal from the head 110a, are transmitted via a flexible cable assembly (FCA) 156 (also referred to as a “flexible cable” and / or “flexible printed circuit board” (FPC)). The connection between the flexible cable 156 and the head 110a may include an arm electronics (AE) module 160, which may include an integrated preamplifier for the read signal as well as other electronic components of the read and write channels. The AE module 160 may be attached to the carriage 134 as shown. The flexible cable 156 may be coupled to an electrical connector block 164, which in some configurations provides an electrical connection through an electrical feedthrough provided by an HDD enclosure 168.The HDD enclosure 168 (also referred to as a “enclosure base” and / or “base plate” and / or simply “base”) in conjunction with an HDD cover provides a semi-sealed (or in some facilities hermetically sealed) protective enclosure for the information storage components of the HDD 100.

[0041] Other electronic components, including a disk controller and servo electronics including a digital signal processor (DSP), provide electrical signals to the drive motor, the voice coil 140 of the VCM, and the head 110a of the HGA 110. The electrical signal provided to the drive motor enables the drive motor to rotate and provide torque to the spindle 124, which in turn is transmitted to the medium 120 attached to the spindle 124. This causes the medium 120 to rotate in a direction 172. The rotating medium 120 creates an air cushion that acts as an air bearing on which the air bearing surface (ABS) of the glider 110b runs, allowing the glider 110b to float above the surface of the medium 120 without coming into contact with a thin magnetic recording layer in which information is recorded.Similarly, in an HDD where a lighter gas than air is used, such as helium as a non-restrictive example, the rotating medium 120 creates a gas cushion that acts as a gas or fluid bearing on which the glider 110b runs.

[0042] The electrical signal supplied to the voice coil 140 of the VCM enables the head 110a of the HGA 110 to access a track 176 on which information is recorded. Thus, the armature 136 of the VCM oscillates through an arc 180, allowing the head 110a of the HGA 110 to access various tracks on the medium 120. Information is stored on the medium 120 in a multitude of radially nested tracks in sectors on the medium 120, such as sector 184. Accordingly, each track is composed of a multitude of sectored track segments (also referred to as a "track sector"), such as a sectored track segment 188. Each sectored track section 188 can include recorded information and a header containing error correction code information and a servo burst signal pattern, such as an ABCD servo burst signal pattern, which is information that identifies the track 176.When accessing track 176, the reading element of the head 110a of the HGA 110 reads the servo burst signal pattern, which provides the servo electronics with a position error signal (PES). This PES controls the electrical signal supplied to the voice coil 140 of the VCM, thus enabling the head 110a to follow track 176. After locating track 176 and identifying a specific sectored track segment 188, the head 110a either reads information from track 176 or writes information to track 176, depending on instructions received by the disk controller from an external agent, for example, a microprocessor of a computer system.

[0043] The electronic architecture of a hard disk drive (HDD) incorporates numerous electronic components for performing their respective functions in operating the HDD, such as a hard disk controller (HDC), an interface controller, an arm electronics module, a data channel, a motor driver, a servo processor, buffer memory, and so on. Two or more such components can be combined on a single integrated circuit board, referred to as a "system-on-a-chip" (SoC). Some, if not all, of these electronic components are typically located on a circuit board that is coupled to the bottom of an HDD, such as the HDD enclosure 168.

[0044] References herein to a hard disk drive, such as the HDD 100, which refers to Fig.As illustrated and described in Figure 1, a data storage device, sometimes referred to as a hybrid drive, may have the functionality of both a conventional hard disk drive (HDD) (see, for example, the HDD 100) and a solid-state storage device (SSD) using non-volatile memory, such as flash memory, or other solid-state memory (e.g., integrated circuits) that is electrically erasable and programmable. Since the operation, management, and control of the different types of storage media typically differ, the solid-state portion of a hybrid drive may include its own corresponding control functionality, which, along with the HDD functionality, can be integrated into a single controller.A hybrid drive can be designed and configured to serve and utilize the solid-state portion in various ways, such as, but not limited to, using the solid-state storage as cache memory, for storing frequently accessed data, for storing I / O-intensive data, and so on. Furthermore, a hybrid drive can essentially be designed and configured as two storage devices in a single enclosure—that is, a traditional hard disk drive and an SSD—with either one or more interfaces for host connectivity. Extensions and alternatives

[0045] The preceding description described embodiments of the invention with reference to numerous specific details that may vary from implementation to implementation. Therefore, various modifications and changes may be made to it without departing from the broader spirit and scope of protection of the embodiments. Thus, the sole and exclusive indicator of what the invention is and what the applicants refer to as the invention is the set of claims arising from this application, in the specific form in which those claims are asserted, including any subsequent amendment. All definitions expressly set forth herein for terms contained in such claims govern the meaning of the terms used in the claims.Therefore, no limitation, element, property, feature, advantage, or attribute that is not expressly mentioned in a claim should in any way restrict the scope of protection of such claim. Accordingly, the description and drawings should be considered illustrative rather than limiting.

[0046] Furthermore, this description may specify that certain process steps can be performed in a particular order, and alphabetical and alphanumeric reference symbols may be used to identify specific steps. Unless expressly stated otherwise in the description, embodiments are not necessarily restricted to a specific order of performing such steps. In particular, the reference symbols are used solely for the convenience of identifying steps and are not intended to specify or require a particular order of execution.

Claims

[1] Hard disk drive (HDD), comprising: Disc media that are rotatably mounted on a spindle; a head glider that houses a read / write converter set up to read from and write to a disc medium of disc media; an actuating assembly designed to move the head slider about a pivot point in order to access sections of the plate medium; a recirculation filter that is positioned upstream of and next to the pivot point, wherein the recirculation filter has: a housing designed to accommodate filter media, the housing having a first section having a first plurality of ribs with a first spacing between them, extending from a side of the housing facing the plate towards the filter media, and a first section of an air chamber, including a closed back, on a side opposite the filter media behind the first set of ribs; and a housing comprising a plate cover upstream of the recirculation filter, wherein the plate cover includes a deflection section configured to direct a gas flow into the air chamber. [2] HDD according to claim 1, further comprising a head stack assembly (HSA) coupled to the actuating assembly and accommodating the head slider, wherein the first plurality of ribs of the first section of the housing is arranged relative to the filter media to reduce the pressure on the disk-facing side of the recirculating filter while the HSA is placed on a loading / unloading ramp. [3] HDD according to claim 1, wherein the first plurality of ribs of the first section of the housing is arranged such that a ratio of a distance between each rib of the first plurality of ribs relative to a depth of these ribs is in a range of one to four. [4] HDD according to claim 1, wherein the recirculation filter further comprises a supply flow path configured to receive a gas flow directed into the air chamber. [5] HDD according to claim 1, wherein: Each of the first multiple ribs of the first section of the casing has an essentially flat outermost surface facing the plate; and the first multitude of ribs is set up with a radius of curvature that essentially corresponds to a radius of curvature of the plate media. [6] HDD according to claim 1, wherein: the housing further comprises a second section downstream of the first section, the second section comprising a second plurality of ribs having a second spacing between them that is greater than the first spacing between the first plurality of ribs, and extending from the side of the housing facing the plate towards the filter media; and The recirculation filter continues to have a second section of the air chamber, including an open rear, on the opposite side of the filter media behind the second set of ribs. [7] HDD according to claim 6, further comprising a head stack assembly (HSA) coupled to the actuating assembly and accommodating the head slider, wherein the second section of the recirculation filter housing is configured to increase, in conjunction with the HSA, the pressure on the disk-facing side of the recirculation filter while it is loaded onto the disk media. [8] HDD according to claim 1, wherein the recirculation filter is positioned inside the housing at a 7 o'clock position. [9] Recirculation filter for a hard disk drive (HDD), wherein the recirculation filter comprises: Filter media; a housing designed to accommodate the filter media, the housing having a first section having a first plurality of ribs with a first spacing between them, extending from a side of the housing facing the plate towards the filter media; a first section of an air chamber, including a closed back, on a side opposite the filter media behind the first set of ribs; and a supply flow path for receiving flow into the air chamber. [10] Recirculating filter according to claim 9, wherein the first plurality of ribs of the first section of the housing is arranged to reduce the pressure on the side of the recirculating filter facing the plate in a first operating mode relative to the filter media. [11] Recirculating filter according to claim 9, wherein the first plurality of ribs of the first section of the housing is arranged such that a ratio of a distance between each rib of the first plurality of ribs relative to a depth of these ribs is in a range of one to four. [12] Recirculating filter according to claim 9, wherein: the housing further comprises a second section downstream of the first section, the second section comprising a second plurality of ribs having a second spacing between them that is greater than the first spacing between the first plurality of ribs, and extending from the side of the housing facing the plate towards the filter media; and The recirculation filter continues to have a second section of the air chamber, including an open rear, on the opposite side of the filter media behind the second set of ribs. [13] Recirculating filter according to claim 12, wherein the second section of the housing of the recirculating filter is configured to increase the pressure on the side of the recirculating filter facing the plate while it is loaded onto the plate media in conjunction with a head stack assembly (HSA). [14] Hard disk drive comprising the recirculation filter according to claim 12. [15] Hard disk drive (HDD), comprising: Disc media that are rotatably mounted on a spindle; Means for reading from and writing to a disk medium of disk media; Means for moving the head glider around a pivot point in order to access sections of the disk medium; a recirculation filter that is positioned upstream of and next to the pivot point, wherein the recirculation filter has: a housing designed to accommodate filter media, the housing having a first section having a first plurality of ribs with a first spacing between them, extending from a side of the housing facing the plate towards the filter media, and a first section of an air chamber, including a closed back, on a side opposite the filter media behind the first set of ribs; and a housing comprising a plate cover upstream of the recirculation filter, the plate cover including means for directing a gas flow into the air chamber. [16] HDD according to claim 15, further comprising a head stack assembly (HSA) coupled to the means for moving and accommodating the means for reading and writing, wherein the first plurality of ribs of the first section of the housing of the recirculation filter is arranged relative to the filter media to reduce the pressure on the side of the recirculation filter facing the disk while the HSA is placed on a load / unload ramp. [17] HDD according to claim 15, wherein the first plurality of ribs of the first section of the housing of the recirculating filter is arranged such that a ratio of a distance between each rib of the first plurality of ribs relative to a depth of these ribs is in a range of one to four. [18] HDD according to claim 15, wherein: the housing of the recirculating filter further comprises a second section downstream of the first section, the second section having a second plurality of ribs having a second spacing between them that is greater than the first spacing between the first plurality of ribs, and extending from the side of the housing facing the plate towards the filter media; and The recirculation filter continues to have a second section of the air chamber, including an open rear, on the opposite side of the filter media behind the second set of ribs. [19] HDD according to claim 18, further comprising a head stack assembly (HSA) coupled to the means for moving and accommodating the means for reading and writing, wherein the second section of the recirculation filter housing is configured to increase, in conjunction with the HSA, the pressure on the disk-facing side of the recirculation filter while it is loaded onto the plurality of disk media. [20] HDD according to claim 15, wherein the recirculation filter is positioned inside the housing at a 7 o'clock position.

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