Disk drive suspension

Abstract

According to one embodiment, a suspension (10) includes a load beam (20) having a recessed portion (50) and a flexible member (21) including a slider mounting portion (30). The convex surface (51) of the recessed portion (50) is in contact with the slider attachment portion (30). The curvature radius (R) of the convex surface (51) is less than 0.10 mm, and the gain defined by the following formula is 0.9 or more. A is the input amplitude, A is the amplitude, R is the curvature radius of the convex surface (51), and Fpr is the pitching resistance of the bending piece. K1 is the pitching rigidity of the air cushion bearing, and k2 is the pitching rigidity of the sliding block mounting part (30).

Description

Technical Field

[0001] The present invention relates to a disk drive suspension, which includes a swingable slider mounting portion, on which a slider is mounted. Background Technology

[0002] Hard disk drives (HDDs) are used in information processing devices, such as personal computers. An HDD includes disks that rotate about a spindle, and a carriage that rotates about a pivot. The carriage includes arms that rotate about a pivot via a positioning motor such as a voice coil motor.

[0003] A disk drive suspension (hereinafter referred to as "suspension") is mounted on the arm of a bracket. The suspension includes a load beam, a flexible member arranged along the load beam, etc. A slider mounting portion is formed near the distal end of the flexible member, on which a slider is mounted. In the art, this slider mounting portion is commonly referred to as a tongue. The slider moves integrally with the slider mounting portion, at least in the pitch direction. Therefore, the pitch angle of the slider mounting portion described herein can also be referred to as the slider pitch angle.

[0004] The universal joint assembly comprises a load-bearing beam, flexible components, and a slider. The slider is equipped with elements for performing access operations, such as data reading and writing. When using a disk drive, data is accessed through the elements of the slider as the disk rotates.

[0005] Examples of suspension systems are disclosed in JP2014-22013A (Patent Document 1) and JP2020-140749A (Patent Document 2). Each suspension system includes a slider mounting portion. The convex surface of a recessed portion contacts this slider mounting portion. The recessed portion is located on a load beam. The slider mounting portion is elastically supported by a universal joint assembly, such as an outer bracket, and swings about the convex surface of the recessed portion. The slider is fixed to the slider mounting portion by means of bonding or other methods. The slider mounting portion described herein refers not only to the bonded portion of the slider but also to its surrounding area. That is, the slider mounting portion refers to the entire swingable area elastically supported by the universal joint assembly.

[0006] As the disk rotates, airflow forms an air cushion bearing between the leading and trailing edges of the slider. In this article, "leading edge" refers to the side where airflow enters the space between the slider and the disk during rotation. "Trailing edge" refers to the side where airflow exits.

[0007] To accommodate the increasing disk recording density, the distance between the slider and the disk tends to decrease. When the disk rotates and forms an air cushion bearing, the example distance between the leading edge of the slider and the disk is 100 nm. Conversely, the example distance between the trailing edge of the slider and the disk is 10 nm.

[0008] Although the disk recording surface appears flat, it may actually contain ripples with amplitudes of several micrometers in the circumferential direction. The inventors tested the disk's flatness. The results showed that the ripple amplitude was larger in the outer circumferential region of the disk compared to the central clamping area near the center of rotation. The slider needs to move in the pitch direction to follow the ripples on the disk surface.

[0009] The slider oscillates relative to the load beam around the convex surface of the recess. As described herein, pitch refers to the movement of the leading edge of the slider away from or towards the load beam along the longitudinal direction of the suspension. The pitch angle is the angle in the pitch direction from the reference position. As described herein, movement of the leading edge of the slider toward the load beam is a positive pitch angle movement. Conversely, movement of the leading edge of the slider away from the load beam is a negative pitch angle movement.

[0010] As the slider moves towards the peak of the disk ripples, it moves along the disk surface at a negative pitch angle. As the slider moves towards the valley of the ripples, it moves along the disk surface at a positive pitch angle.

[0011] The slider is tilted relative to the disk surface at a small positive pitch angle. This pitch angle is typically very small, for example, 0.006°. When the ripple amplitude is, for example, 3 to 6 μm, the slider needs to be adjusted in the pitch direction at a relatively large angle, for example, ±0.03° to ±0.06°.

[0012] Recently, with the development of disk drives, suspension lengths have tended to shorten. A load beam is positioned at a specific angle relative to the disk surface in the pitch direction. A slider mounting portion located at the top of the load beam moves about a recessed portion relative to the load beam in the pitch direction. When the suspension length is shortened, the angle change of the slider in the pitch direction increases. It is known, for example, that when the suspension length becomes approximately 6 mm, the amount of slider angle change will increase.

[0013] If the slider cannot quickly follow the disk's ripples, it may come too close to the disk surface. Subsequently, friction will create high-temperature areas on the slider, disk, or air bearing. In extreme cases, the slider may come into contact with the disk, causing damage to either the disk or the slider.

[0014] Through in-depth research, the inventors discovered that in areas of significant pitch angle change, such as near the peaks or valleys of the disk's ripples, the slider sometimes approaches the disk excessively. Based on this, the inventors realized that the gain value relative to the input amplitude plays a crucial role in preventing interference between the disk and the slider. A detailed explanation of this gain is provided below.

[0015] Traditionally, it is believed in the art that the slider mounting portion, such as the tongue, oscillates in a state of essentially single-point contact with the convex surface of the recess. Since the contact between the convex surface of the recess and the slider mounting portion is equivalent to the contact between a sphere rolling on a plane and a plane, this contact is considered a Hertzian elastic contact. In Hertzian elastic contact, the friction between the slider mounting portion (plane) and the convex surface (sphere) of the recess can be effectively ignored. Therefore, conventional understanding does not consider the influence of convex surface friction on the motion of the slider mounting portion.

[0016] The embodiments described herein generally relate to providing a disk drive suspension capable of suppressing interference between the rotating disk and the slider. Summary of the Invention

[0017] Through in-depth research, the inventors discovered that a friction-like force, opposite to the pitch direction, is generated at the contact point between the convex surface of the recess and the slider mounting part. This force is defined as Flexure Pitching Resistance (Fpr). When the slider mounting part oscillates on the convex surface of the recess, the Flexure Pitching Resistance (Fpr) is generated at the contact point between the slider mounting part and the convex surface.

[0018] According to one embodiment, a suspension includes a load beam with a recess and a flexible member disposed along the load beam. The flexible member includes a slider mounting portion on which a slider is mounted. The slider mounting portion has a first surface facing the load beam and a second surface on which the slider is fixed by adhesive or similar means. The convex surface of the recess contacts the first surface of the slider mounting portion at a contact point. The slider mounting portion is supported by a universal joint assembly to achieve oscillation at least in the pitch direction. The suspension of this embodiment effectively avoids interference between the disk and the slider by setting the gain to 0.9 or higher. The definition of gain will be detailed later.

[0019] When the gain reaches 0.95 or higher, the suspension can more effectively avoid interference between the disk and the slider. It was also found that the radius of curvature of the convex surface and the pitch drag (Fpr) of the flexure element affect the gain. In this embodiment, the radius of curvature of the convex surface is less than 0.10 mm, less than 0.04 mm, or even smaller. More preferably, the radius of curvature of the convex surface is less than 0.85 mm. The pitch drag (Fpr) of the flexure element is 0.005 N or even smaller.

[0020] According to an embodiment of the present invention, the suspension can suppress interference between the slider and the disk that moves in the pitch direction in response to the ripples of the rotating disk.

[0021] Other objects and advantages of the present invention will be set forth in the following description, some of which may be derived directly from the description or learned by practicing the invention. The objects and advantages of the invention may be achieved by the technical means and combinations thereof specifically pointed out below. Attached Figure Description

[0022] The accompanying drawings, which form part of the specification, illustrate embodiments of the present invention and, together with the above overview and the detailed description of specific embodiments below, serve to explain the principles of the present invention.

[0023] Figure 1 This is a plan view of a portion of the suspension according to one embodiment.

[0024] Figure 2 For along Figure 1 A cross-sectional view of the suspension and part of the slider taken from the F2-F2 line.

[0025] Figure 3 This is a cross-sectional view of an example disk drive.

[0026] Figure 4 for Figure 2 A schematic side view of the suspension, slider, and part of the disk shown.

[0027] Figure 5 for Figure 4 A schematic side view showing the slider moving in a negative pitch direction.

[0028] Figure 6 for Figure 4 A schematic side view showing the slider moving in the positive pitch direction.

[0029] Figure 7 for Figure 4 The diagram shows the suspension, slider, and disk motion system.

[0030] Figure 8 A graph showing the relationship between the calculated slider pitch angle and the disk rotation angle.

[0031] Figure 9 This is a graph showing the relationship between the actual slider pitch angle and the disk rotation angle.

[0032] Figure 10 This is a schematic diagram showing the relationship between the disk outline and the slider pitch angle.

[0033] Figure 11 This is a graph showing the relationship between the disk pitch angle and the slider pitch angle in an example with a gain of 0.701.

[0034] Figure 12 The graph shows the relationship between disk pitch angle and slider pitch angle in the example with a gain of 0.934.

[0035] Figure 13 The graph shows the relationship between the disk pitch angle and the slider pitch angle in the example with a gain of 0.105.

[0036] Figure 14This is a schematic diagram of the gain values ​​for samples 1 to 17.

[0037] Figure 15 The graph shows the relationship between the pitch resistance Fpr of the flexure and the gain.

[0038] Figure 16 This is a graph showing the relationship between the radius of curvature R of the convex surface and the gain. Detailed Implementation

[0039] The following description, in conjunction with the accompanying drawings, describes an embodiment of a disk drive suspension. This disk drive suspension will be referred to simply as a suspension.

[0040] Figure 1 This is a plan view of part of the suspension 10. Figure 2 For along Figure 1 A cross-sectional view of the suspension 10 taken from the F2-F2 line. Figure 3 This is an exemplary cross-sectional schematic diagram of a disk drive 11 including a suspension 10. The disk drive 11 has one or more disks 12. A detailed description of the disk drive 11 will follow later; the suspension 10 will be described first.

[0041] The suspension 10 includes a load beam 20 and a flexible member 21 disposed along the load beam 20. The load beam 20 is made of stainless steel sheet and extends along the length of the suspension 10. Figure 1 The direction indicated by the double arrow X1 is the longitudinal direction of the load beam 20, which is also the longitudinal direction of the suspension 10. The thickness of the load beam 20 is, for example, 20 to 40 μm, but other thickness values ​​may also be used.

[0042] The flexible member 21 includes a metal substrate 22 made of a thin stainless steel sheet and wiring portions 23 disposed along the metal substrate 22. An example value for the thickness of the metal substrate 22 is 20 μm (12 to 25 μm). The thickness of the metal substrate 22 is less than the thickness of the load beam 20.

[0043] like Figure 1 As shown, the metal substrate 22 is fixed to the load beam 20 by multiple welded portions (e.g., first welded portion W1 and second welded portion W2). The wiring portion 23 includes a base insulating layer made of an electrically insulating resin such as polyimide, a plurality of conductors formed on the base insulating layer, and a cover layer covering the conductors.

[0044] A portion of the metal substrate 22 has a slider mounting portion 30 formed thereon. In the art, this slider mounting portion 30 may be referred to as a tongue. As used herein, "slider mounting portion" refers to a component in a flexible member on which a slider is mounted. In other words, "slider mounting portion" is also referred to as a "slider mounting part" or "the part on which the slider is to be mounted." Figure 2As shown, the slider mounting portion 30 has a first surface 30a and a second surface 30b. The first surface 30a faces the load beam 20. The second surface 30b is located on the side opposite to the first surface 30a in the thickness direction of the metal substrate 22. The slider 31 is fixed to the second surface 30b by means of adhesive or the like.

[0045] A slider 31 is disposed on the second surface 30b of the slider mounting portion 30, with the wiring portion 23 located therebetween. A portion of the slider 31 is fixed to the slider mounting portion 30 by adhesive. The slider 31 has a leading edge portion 31a and a trailing edge portion 31b relative to the rotation direction of the disk 12. As used herein, "leading edge" refers to the side where airflow enters the space between the disk 12 and the slider 31 when the disk rotates. "Trailing edge" refers to the side where airflow exits.

[0046] The trailing edge 32 of the slider 31 is provided with a plurality of elements 33 capable of converting magnetic signals to electrical signals. (An example of element 33 is an MR element.) These elements 33 are used for access, such as reading data from or writing data to the recording surface of the disk 12. A heater 34 may be provided near the elements 33, and when current is applied to the heater 34, the trailing edge 31b expands due to heat. This increases the distance h1 between the trailing edge 31b and the disk 12 (see...). Figures 4 to 6 This can be further reduced. For example, the spacing h1 can be reduced to 1 nm or less.

[0047] The distance h1 between the trailing edge 31b of slider 31 and disk 12 can be called the head-to-disk pitch (HMS). This distance h1 is smaller than the distance h2 between the leading edge 31a and disk 12. Here, h2 is, for example, 100 nm, while h1 is, for example, 10 nm.

[0048] like Figure 1 As shown, the slider mounting portion 30 is elastically supported on the load beam 20 via a universal joint assembly 40. An example of this universal joint assembly 40 includes first arms 41 and 42 and second arms 43 and 44. The first arms 41 and 42 and the second arms 43 and 44 are formed from portions of the metal base 22. The universal joint assembly 40 can vary depending on the design of the flexible element 21 and is not limited to it. Figure 1 The illustrated embodiment.

[0049] The universal joint portion 45 is formed within the flexible member 21 via the slider mounting portion 30, the universal joint assembly 40, etc. The slider mounting portion 30 is a swingable component that elastically supports the universal joint assembly 40. The slider mounting portion 30 includes the portion where the slider 31 is bonded and its surrounding area. Actuating elements 46 and 47 can be provided on both sides of the slider 31. The actuating elements 46 and 47 are made of piezoelectric materials, such as lead zirconate titanate (PZT). By applying a voltage to the actuating elements 46 and 47, the trailing edge 31b of the slider 31 can be slightly rotated in the width direction.

[0050] The distal ends of the first arms 41 and 42 are each supported on the load beam 20 by a first welded part W1. The proximal ends 43a and 44a of the second arms 43 and 44 are each fixed to the load beam 20 by a second welded part W2. The slider mounting part 30 is elastically supported by a universal joint assembly 40 so that it can swing relative to the load beam 20.

[0051] Limiting members 48 and 49 may be provided between the slider mounting portion 30 and the distal end 21a of the flexible member 21. Limiting members 48 and 49 are made of resin such as polyimide. Limiting members 48 and 49 are used to suppress excessive oscillation of the slider mounting portion 30 when the suspension 10 is subjected to external impact. Depending on the design of the flexible member 21, limiting members 48 and 49 can also serve as part of the universal joint assembly 40.

[0052] A recess 50 is formed on the load-bearing beam 20. For example... Figure 2 As shown, the recess 50 has a convex surface 51 that protrudes in a dome shape towards the slider mounting portion 30. This convex surface 51 is shaped by rotating an arc with a radius of curvature R about the vertical axis Y. Therefore, the convex surface 51 appears approximately circular in the top view of the slider mounting portion 30. The arc with the radius of curvature R does not need to be a perfect circle. In other words, the convex surface 51 is shaped similarly to a portion of a hemisphere. The apex of the convex surface 51 contacts the first surface 30a of the slider mounting portion 30. The radius of curvature R refers to the radius of curvature at the point where the slider mounting portion 30 may contact the first surface 30a when it swings. The remaining portion, i.e., the portion not in contact with the first surface 30a, may have a radius of curvature different from R.

[0053] like Figure 2 As shown, the convex surface 51 of the recessed portion 50 contacts the slider mounting portion 30. In this state, the slider mounting portion 30 can be positioned at least in the pitch direction ( Figure 2 (As indicated by the double arrow P) oscillates. This causes the slider mounting portion 30 to generate at least a vertical displacement centered on the convex surface 51. The slider mounting portion 30 is supported by a universal joint assembly 40 so that it can oscillate relative to the load beam 20, at least in the pitch direction (vertical oscillation direction) and the roll direction (lateral oscillation direction). The universal joint assembly 40 may include an outer support member, an arm, etc.

[0054] Figure 3 This is an exemplary cross-sectional schematic diagram of a disk drive (HDD) 11. The HDD 11 includes a disk 12, a housing 70 (partially shown), a bracket 72, a positioning motor 73 for driving the bracket 72, etc. The disk 12 rotates about a spindle. The bracket 72 is rotatable about a pivot 71. The housing 70 is sealed by a cover. A suspension 10 is mounted at the end of the arm 74 of the bracket 72.

[0055] When the positioning motor 73 drives the bracket 72 to rotate, the suspension 10 moves radially along the disk 12. The slider 31 thus moves to the desired position on the disk 12. As the disk 12 rotates, airflow flows from the leading edge 31a to the trailing edge 31b of the slider 31. This forms an air cushion bearing 80 between the disk 12 and the slider 31.

[0056] Figure 4 The schematic diagram shows the surface 12a of the disk 12, the slider 31, and the recess 50 along the planar reference plane N. The reference plane N is a virtual plane extending perpendicular to the central axis of the rotating disk 12. The slider mounting portion 30, elastically supported by the universal joint assembly 40, remains in contact with the convex surface 51. Therefore, the slider mounting portion 30 and the convex surface 51 are in contact with each other at the contact portion 90.

[0057] When the slider mounting part 30 is in contact with the convex surface 51 at the contact portion 90, it moves around the center of curvature Z1 to roll around the convex surface 51. At this time, the convex surface 51 and the slider mounting part 30 have an elastic contact between a plane and a sphere (Hertzian elastic contact). Therefore, it is conventionally believed that there is no sliding at the contact portion and friction loss is negligible.

[0058] However, it was actually discovered that a type of frictional force acts on the contact portion 90 between the slider mounting part 30 and the convex surface 51. This force is the pitch resistance Fpr of the flexural member discovered by the inventors. The pitch resistance Fpr of the flexural member can be obtained through analysis of the design of the flexible member 21 (mainly the design of the universal joint part 45).

[0059] Figure 5 The diagram schematically shows slider 31 moving along surface 12a with a negative pitch angle θ1 relative to reference plane N. When slider 31 moves along surface 12a with a negative pitch angle θ1, contact portion 90 moves from reference line Y1 along the first direction P1, and slider mounting portion 30 rotates without substantial sliding on the surface of convex surface 51. At this time, a flexural pitch resistance Fpr, opposite to the direction of movement of slider mounting portion 30, acts tangentially along convex surface 51 on contact portion 90. Slider 31 is mounted on slider mounting portion 30. Therefore, the pitch angle of slider 31 and the pitch angle of slider mounting portion 30 described herein are synonymous.

[0060] The pitch resistance Fpr of the flexural element acts on the contact portion 90 with the radius of curvature R as the lever arm. Therefore, the torque around the center of curvature Z1 is expressed as the product of the pitch resistance Fpr and the radius of curvature R (Fpr×R), which acts on the slider mounting portion 30. This torque increases with the radius of curvature R, generating resistance to the movement of the slider mounting portion 30 in the pitch direction.

[0061] Figure 6 The schematic diagram shows slider 31 moving along surface 12a with a positive pitch angle θ2 relative to reference plane N. (Example) Figure 6As shown, when the slider 31 moves along the surface 12a at a positive pitch angle θ2, the contact portion 90 moves from the reference line Y1 along the second direction P2, and the slider mounting portion 30 rotates on the convex surface 51 without substantial sliding. At this time, the pitch resistance Fpr of the flexural member, which is opposite to the direction of movement of the slider mounting portion 30, acts tangentially on the contact portion 90 along the convex surface 51.

[0062] Figure 7 This is a schematic diagram of a motion system including slider 31. (The following text and...) Figure 7 In the formula shown, k1 is the pitch stiffness of the slider surface 31c facing the air cushion bearing 80 [Nm / rad]. k2 is the pitch stiffness of the universal joint portion 45 of the flexible member 21 [Nm / rad]. c is the viscous damping coefficient between the slider surface 31c facing the air cushion bearing 80 and the universal joint portion 45. ζ is the viscous damping ratio. θ is the slider pitch angle [rad], a is the input amplitude [rad], Fpr is the pitch resistance of the flexible member [N], R is the radius of curvature R of the convex surface of the recess [m], and ω is the angular frequency [rad / s]. I is the inertia (mass) of the slider 31 including the slider mounting portion 30, but for the sake of simplifying the calculation, only the inertia (mass) of the slider 31 is considered.

[0063] Fpr×R is the resistance torque opposite to the direction of rotation. Therefore, its single-degree-of-freedom motion equations are shown in the following formulas (1) and (2).

[0064] -when

[0065]

[0066] -when

[0067]

[0068] K1; Pitch stiffness of the air cushion bearing surface (ABS); K2; Pitch stiffness of the flexible component (Fx).

[0069] C; Viscous damping coefficient of flexible component (Fx),

[0070] R; radius of the recess, F pr ; Flexural resistance pitching force

[0071] θ; Slider pitch angle,

[0072] a; Input amplitude, I; Slider inertia.

[0073] ω; angular frequency.

[0074] By transforming equations (1) and (2), we obtain the following equations (3) and (4).

[0075] -when

[0076]

[0077] -when

[0078]

[0079] here, The natural angular frequency, and Let be the viscous damping ratio. In equations (3) and (4), the principle of linear superposition holds. Therefore, the steady-state vibration solution is assumed to be as follows (5).

[0080] θ p =U sinωt + Vcosωt + C … (5)

[0081] such as θ p , Substituted into equations (3) and (4),

[0082] -when

[0083]

[0084] -when

[0085]

[0086] When comparing the left and right sides

[0087] -when

[0088]

[0089] 2ξω0ωU+(ω0 2 -ω 2 V = 0

[0090]

[0091] -when

[0092]

[0093] 2ξω0ωU+(ω0 2 -ω 2 V = 0

[0094]

[0095] When U, V, and C are obtained from the above formula,

[0096] U and V and when time and when The same as the current expression.

[0097]

[0098] C as when time and when It has changed with the current style of expression.

[0099] -when

[0100]

[0101] -when

[0102]

[0103] The steady-state solution θp is obtained from equations (6) to (9).

[0104] θ p =U sinωt+Vcosωt+C=Asin(ωt-δ)+C

[0105] When the resistance torque (pitch resistance Fpr of the flexure) is zero, the amplitude A and phase δ are expressed by the following formulas.

[0106] amplitude

[0107] phase

[0108] When Fpr is 0 (N) and the sign of the constant term C remains unchanged, the disk pitch angle matches the slider pitch angle. However, when there is a resistance torque Fpr and the sign of the constant term C changes, the disk pitch angle and the slider pitch angle do not match.

[0109] Figure 8 This displays the relationship between the disk rotation angle and the calculated slider pitch angle when Fpr is 0.01N. Figure 8 In this context, when the disk rotation angle is between 0° and 90°, the constant term C is negative. Therefore, the slider pitch angle is smaller than the disk pitch angle.

[0110] Figure 8 In the calculation, when the disk rotation angle exceeds 90°, the constant term C becomes positive. Consequently, the slider pitch angle increases discontinuously at 90° and exceeds the disk pitch angle. When the disk rotation angle exceeds 270°, the constant term C becomes negative. Therefore, calculations show that the slider pitch angle decreases discontinuously at 270°. When the disk rotation angle is between 270° and 450°, the change in slider pitch angle lags behind the change in disk pitch angle.

[0111] When ξ = 0 and phase δ = 0, the solution is expressed by the following equation.

[0112] θ p =Asin(ωt)+C

[0113] -0 < disk angle < 90 degrees, 270 < disk angle < 360 degrees

[0114]

[0115] -90 < Disk angle < 270 degrees

[0116]

[0117] Therefore, within the aforementioned θ range, the slider pitch angle increases or decreases at a constant angle C. The change in the slider pitch angle is as follows: Figure 9 As shown. This phenomenon will be combined with Figure 9 and Figure 10 This will be explained below. It should be noted that the slider pitch angle is equivalent to the slider mounting pitch angle. As described herein, the slider mounting pitch angle can also be referred to as the slider pitch angle.

[0118] Figure 10 The schematic diagram shows the relationship between the profile of the rotation direction of the disk 12 surface and the slider pitch angle. Figure 10 The solid line L1 represents the disk outline. Figure 10 The dashed line L2 in the figure represents the movement trajectory of the slider along the surface of disk 12 when C=0.

[0119] like Figure 9 and Figure 10 As shown, when the disk rotation angle is between 0° and 90°, the disk pitch angle is positive. Therefore, the disk pitch angle changes in the direction of increase. Thus, when the slider rotates in the positive pitch direction, Fpr is a negative value. Therefore, as... Figure 10 As shown by the solid line S1, the slider pitch angle lags positively relative to the disk pitch angle due to the resistance of Fpr.

[0120] When the disk rotation angle exceeds 90°, the disk pitch angle changes in the direction of decreasing disk pitch angle (negative pitch direction), causing Fpr to change from a negative value to a positive value. Therefore, as Figure 10 As shown by the dashed line S2, when the disk rotation angle exceeds 90°, the positive value Fpr applies a positive pitching force to the slider.

[0121] However, when the disk rotation angle exceeds 90°, the disk pitch angle changes towards the negative pitch direction. Therefore, even with a positive Fpr action, the positive pitch rotation of the slider is still suppressed. Thus... Figure 10 As shown in shaded area S3, the slider pitch angle θp remains constant during the period when the disk rotation angle exceeds 90° to 180°.

[0122] When the disk rotation angle exceeds 180°, the disk pitch angle becomes negative and its absolute value increases. At this time, because Fpr is positive, the resistance generated by Fpr acts in the direction that reduces the slider's pitch angle. Therefore, as... Figure 10 As shown in S4, before the disk rotation angle approaches 270°, the change in slider pitch angle lags behind the disk pitch angle.

[0123] When the disk rotation angle exceeds 270°, the disk pitch angle changes in the positive direction, causing Fpr to change from a positive value to a negative value. Therefore, when the disk rotation angle exceeds 270°, the negative Fpr exerts a negative pitch force on the slider.

[0124] However, when the disk rotation angle exceeds 270°, the disk pitch angle changes towards positive pitch. Therefore, even with negative Fpr action, the negative pitch rotation of the slider is suppressed. Thus, the slider pitch angle remains constant between 270° and 360°. When the disk rotation angle exceeds 360°, the same phenomenon that occurs between 0° and 360° will repeat.

[0125] like Figure 9 As shown, when the input amplitude is a, the gain is expressed by the following formula. Where A is the amplitude, R is the radius of curvature of the convex surface 51, Fpr is the pitch resistance of the flexure, k1 is the pitch stiffness of the air cushion bearing, and k2 is the pitch stiffness of the slider mounting part 30.

[0126]

[0127] Figure 11 The relationship between disk pitch angle and slider pitch angle is shown in the example with a gain of 0.701. Figure 11 In the example, the large difference between the disk pitch angle and the slider pitch angle may cause interference between the slider and the disk.

[0128] Figure 12 The example showing the gain of 0.934 demonstrates the relationship between the disk pitch angle and the slider pitch angle. Figure 12 In the example, because the difference between the disk pitch angle and the slider pitch angle is small, the possibility of interference between the slider and the disk is low.

[0129] Figure 13 The relationship between disk pitch angle and slider pitch angle is shown in the example with a gain of 0.105. Figure 13 In the example, because the pitch angle of the disk and the pitch angle of the slider are significantly different, the possibility of interference between the slider and the disk is relatively high.

[0130] Figure 14The gain values ​​of suspension samples 1 through 17 are displayed. Samples 1 through 9 are deemed unacceptable (NG) because their gain is too low, which may cause interference between the slider and the disk. Samples 10 through 17 successfully avoid interference between the slider and the disk. To avoid interference, the gain must be 0.9 or higher, preferably 0.95 or higher.

[0131] Figure 15 This shows the relationship between the pitch resistance Fpr of the flexure and the gain. The pitch resistance Fpr affects the gain. The smaller the Fpr, the greater the gain. In particular, when Fpr is less than 0.005N, the gain is closer to the desired value. Figure 16 Analysis results of the relationship between the radius of curvature R of the depression and the gain when Fpr = 0.005N: When the radius of curvature R of the depression is less than 0.1, the gain can approach 0.9. In particular, when the radius of curvature R is less than 0.085, the gain can be set to 0.9 or higher.

[0132] Through in-depth research, the inventors discovered that setting the gain to 0.9 or higher, preferably 0.95 or higher, can effectively suppress interference between the slider and the disk. To achieve a gain of 0.9 or higher, the pitch resistance Fpr of the flexure needs to be set to 0.005N or less, and the radius of curvature R of the convex surface needs to be set to less than 0.10mm, more preferably less than 0.085mm.

[0133] Due to limitations of the molding die for the recessed portion 50, the radius of curvature R is practically difficult to be less than 0.04 mm. Therefore, the radius of curvature R is set to 0.04 mm or greater. The height of this recessed portion h3 (see...) Figure 4 Examples are 0.04mm to 0.07mm, but other height values ​​may also be used.

[0134] When implementing this invention, various modifications can be made to the specific shapes and positions of the suspension components (including load beams, flexible elements, sliders, and recesses). The disk drive is not limited to the above embodiments and can be implemented in various forms as needed.

[0135] Other advantages and modifications will be readily apparent to those skilled in the art. Therefore, the present invention is not limited in its specific details and representative embodiments shown and described herein. Consequently, various modifications may be made without departing from the overall inventive concept and scope defined by the appended claims and their equivalents.

Claims

1. A disk drive suspension, characterized in that, include: Load-bearing beam (20); A flexible member (21) provided along the load beam (20) includes a slider mounting portion (30) on which a slider (31) is mounted, the slider mounting portion (30) having a first surface (30a) facing the load beam (20) and a second surface (30b) on which the slider (31) is provided; A recess (50) formed on the load beam (20) has a convex surface (51) that contacts the first surface (30a) of the slider mounting portion (30); and A universal joint assembly (40) for pivotally supporting a slider mounting portion (30) in at least the pitch direction, wherein the radius of curvature (R) of the convex surface (51) in contact with the slider mounting portion (30) is less than 0.10 mm and less than 0.04 mm or smaller. And the gain is 0.9 or higher as defined by the following formula: a: Input amplitude A: Amplitude R: Radius of curvature of the convex surface of the recess F pr Flexural component pitch resistance K1: Air cushion bearing pitch stiffness K2: Pitch stiffness of flexible component (universal joint).

2. The suspension according to claim 1, characterized in that, The gain is 0.95 or higher.

3. The suspension according to claim 1, characterized in that, The radius of curvature (R) of the convex surface (51) is less than 0.85 mm.

4. The suspension according to claim 1, characterized in that, When the slider mounting part (30) moves in the pitch direction, the pitch resistance of the flexure acting on the contact part that contacts the convex surface (51) is 0.005N or less.

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