Abstract:
When a negative pressure slider is used in the magnetic head support mechanism with a loading/unloading function, the gimbals is likely to be deformed or damaged. Apart from the first tab provided to the front end of the suspension, the second tab is provided to the front end of the gimbals. In addition to the Suspension supporting ramp, the ramp portion has the second ramp for supporting the gimbals. This arrangement allows the slider mounting gimbals, in addition to the suspension, to be loaded/unloaded. Unlike the conventional drive in which only the suspension is loaded/unloaded, this arrangement enables the gimbals to be loaded/unloaded while maintaining a predetermined space between the gimbals and the suspension, thus reducing the risk of gimbals deformation and damage.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a magnetic head support mechanism for a magnetic disk drive and more particularly to a magnetic head support mechanism with a loading/unloading mechanism which reduces deformations of and damages to a gimbals during unloading and has excellent impact resistance during operation. 
     In a magnetic disk drive with a conventional loading/unloading mechanism, as disclosed in JP, 8-255320, A a tab provided to the front end of a suspension rides over an inclined portion of a parking mechanism when a disk stops, thereby preventing a contact between a slider and a disk. This eliminates a problem of the slider sticking to the disk due to their contact (the slider and the disk get stuck together, resulting in the disk failing to rotate or the slider failing to float). 
     To realize a uniform floating distance (height of the slider from the disk surface) over the entire surface of the disk, the slider of recent years employs a negative pressure. The slider using a negative pressure (referred to as a negative pressure slider), as disclosed in U.S. Pat. No. 4,420,780, has a pocket formed in that surface of the slider facing the disk to generate a pressure lower than the atmospheric pressure (negative pressure) to make uniform the floating force that would otherwise vary depending on the position along the disk radius, thereby achieving a uniform floating distance. 
     A problem addressed by the present invention is that, where the conventional negative pressure slider is used as the suspension for the loading/unloading mechanism, the slider stays on the disk surface due to the negative pressure while in an unloaded state and the application of a separation force overcoming the negative pressure may deform the gimbals. 
     OBJECT AND SUMMARY OF THE INVENTION 
     An object of the present invention is to prevent the gimbals of the suspension from being deformed and damaged during unloading. 
     To achieve the above objective, the magnetic head support mechanism, which has a magnetic head carrying slider and a suspension that holds the slider against the disk surface from the back of the slider (i.e., from the side opposite the disk facing side), is characterized in that the suspension has a gimbals (also called a flexure) and a load beam and that the load beam is provided at its front end with a first tab and the gimbals is provided at its front end with a second tab. Outside the disk of the magnetic disk drive, a loading/unloading inclined portion (hereinafter referred to as a ramp) is provided. The ramp has a first ramp and a second ramp corresponding to the first tab and the second tab. During the loading/unloading operation, the first tab pulls the load beam away from the disk surface and the second tab pulls the slider away from the disk surface. This allows the loading/unloading operation to be carried out without deforming the gimbals even when the negative pressure slider is used. 
     Further, the friction of sliding portions as well as dust produced in the sliding portions can be reduced by applying a lubricating film or lubricating agent to one or both of sliding surfaces between the first tab and the first ramp and between the second tab and the second ramp, or by forming the sliding surfaces from a material excellent in the lubrication performance. With this arrangement, dust no longer adheres to the slider or causes floating height variations, assuring high reliability. 
     Further, the ramp is formed so that the second ramp begins at a position behind where the first ramp begins. So, when the disk rotation stops, the first tab and the first ramp contact first, followed by the contact between the second tab and the second ramp. In other words, the first tab lifts the load beam first and then the second tab lifts the slider. Therefore, the slider can be pulled up with a zero slider pressing load. 
     As a result, the slider can easily be pulled up and the wear of the second ramp can be reduced. During the loading operation, the slider is first lowered (or loaded) onto the disk surface and is then applied with a load. It is therefore possible to prevent damages which would otherwise be caused by the slider contacting the disk. 
     Because the first tab is formed longer than the second tab, the second ramp does not need to be formed directly below the first ramp. In other words, the second ramp can be formed by the side of the first ramp, which enables the ramp to have a sufficient strength. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing an overall construction of the magnetic disk drive of the present invention. 
     FIG. 2A is a plan view showing the magnetic head support mechanism of a first embodiment of the invention. 
     FIG. 2B is an enlarged view of an encircled part of FIG.  2 A. 
     FIG. 2C is a cross section taken along the line IIC—IIC of FIG.  2 B. 
     FIG. 3A is a plan view showing a gimbals of the first embodiment installed in place. 
     FIG. 3B is a plan view of the gimbals. 
     FIG. 3C is a front view of the gimbals. 
     FIG. 3D is a side view of the gimbals. 
     FIG. 4 is a side view showing the first embodiment at rest. 
     FIG. 5A is a perspective view of a ramp of the invention. 
     FIG. 5B is a side view of the ramp of FIG.  5 A. 
     FIG. 6A is a side view showing a conventional gimbals structure resting on the ramp. 
     FIG. 6B is a s id e view showing a gimbals structure of the invention resting on the ramp. 
     FIG. 7A is a schematic view of an impact tester. 
     FIG. 7B is a graph of impact test results. 
     FIG. 8 is a perspective view showing another ramp of the invention. 
     FIG. 9 is a side view showing another tab of the invention. 
     FIG. 10A is a side view showing another tab structure of the invention in a floated state. 
     FIG. 10B is a side view showing the tab structure of FIG. 10A resting on the ramp. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The first embodiment of the present invention will be described by referring to FIG.  1  through FIG.  7 . To explain about the operational or performance difference between a conventional magnetic head support mechanism and a mechanism of the invention, structural differences between these magnetic head support mechanisms are shown in FIG.  6 . 
     FIG. 1 shows an overall view of a magnetic disk drive mounting the magnetic head support mechanism of the invention. 
     Magnetic disks  1  for recording information are mounted in layers on a spindle. A magnetic head (not shown) for recording and reproducing information onto and from the magnetic disk  1  is mounted on a slider (not shown) of a magnetic head support mechanism  2 . The magnetic head support mechanism  2  is connected to an arm  6 . The magnetic head is positioned at a predetermined radial position by a positioning mechanism  7  including a pivot, a bearing and a voice coil motor. These mechanisms are accommodated in a lunchbox-shaped base  8  and sealed by a cover (not shown). The magnetic head support mechanism  2 , when the disk is at rest, has its front end supported on a ramp  5  which is provided outside the magnetic disk  1 . 
     FIG. 2A shows an overall view of the magnetic head support mechanism as the first embodiment of the invention. 
     An arm mounting portion  20  is connected to a spring portion  21 , which in turn is connected to a load beam  22 . The front end of the load beam  22  is provided with a pivot  23  and a first tab  24 . FIG. 2B shows an enlarged view of a portion A of FIG.  2 A. Around the pivot  23  is formed a window  230 , through which a part of a slider mounting gimbals  31  shows. This window  230  is used to insert a jig for gripping the gimbals or slider to weld the slider to the gimbals. 
     FIG. 2C shows a cross section taken along the line IIC—IIC. 
     A joint portion  25  of the gimbals  31  is welded at one end to the load beam  22  and at the other end is connected to a flexible finger portion  26 , which has a step portion  27 , a lateral frame  28 , a mounting portion  29  and a second tab  30 . The mounting portion  29  is attached with a slider  40  and applied with a pressing load from a side opposite the slider  40  by the pivot  23 . 
     The first tab  24  is provided at the front end of the load beam  22  and the second tab  30  at the front end of the gimbals  31 . The second tab  30  is located below the first tab  24  (i.e., on the slider side) without contacting it. The second tab  30  is formed shorter than the first tab  24 . In this example, the difference in length between the two tabs is called L. The gimbals  31  is also kept out of contact, except at one end of the joint portion  25 , with the load beam  22  and the first tab  24 . 
     FIG. 3A shows the slider mounting side of the portion A of FIG.  2 A. 
     As shown in the figure, the slider  40  is mounted on the mounting portion  29  of the gimbals  31 . The other end of the mounting portion  29  is connected to the lateral frame  28 , which has its ends connected to the step portion  27  which in turn is connected to the flexible finger portion  26 . The second tab  30  is formed by extending the lateral frame  28  in a direction opposite the slider  40 . 
     FIG. 3B shows the detail of the gimbals  31  attached with the second tab  30 . FIG. 3C shows the gimbals as seen from its end and FIG. 3D shows the cross section of the gimbals cut along the center line. 
     As shown in these figures, the mounting portion  29 , the lateral frame  28  and the second tab  30  are formed on almost the same plane. The height of the flexible finger portion  26  from these portions is determined by the height of the step portion  27 . The second tab  30  may be bent in U shape to improve its mechanical strength. 
     FIG. 4 shows the magnetic head support mechanism  2  pulled away from the disk surface by the loading/unloading inclined surface (hereinafter referred to as a ramp  51 ) (in an unloaded state). The ramp  51  is formed with a first ramp  52  and a second ramp  53 . The first tab  24  is applied a separation force F 1  from the first ramp  52  and the second tab  30  is applied a separation force F 2  from the second ramp  53 , with the result that they are unloaded from the disk surface. 
     FIG. 5A shows the detail of the ramp and FIG. 5B shows the difference in dimension between the first ramp and the second ramp. 
     As described above, the ramp  51  has two ramps, first ramp  52  and second ramp  53 . The first ramp  52  has an inclined portion  52 A and a flat portion  52 B. The second ramp  53  similarly has an inclined portion  53 A and a flat portion  53 B. As the disk rotation stops, the first tab and the second tab of the magnetic head support mechanism are pulled away from the disk surface by the inclined portions  52 A,  53 A and held on the flat portions  52 B,  53 B. The flat portions may be formed with a recess or inclination to securely hold the tab. The second ramp is provided nearer to the magnetic head support mechanism  2  than the first ramp by a distance of about L 3  and the width of the second ramp is provided by a distance of L 4 . This is due to the difference in length L between the first tab and the second tab. The height difference H between the flat portion of the first and second ramps is set almost equal to the height difference H between the first and second tabs. These arrangements combine to prevent the deformation of gimbals during unloading. 
     FIG. 5B details the difference between the first ramp and the second ramp. Changing the positional difference L 3  between the first ramp and the second ramp can adjust the unloading/loading timings of the suspension and the slider. In this embodiment, the second ramp is provided a distance L 3  behind the first ramp. With this arrangement, during the unloading operation, the suspension is first pulled away from the disk surface, followed by the slider. This allows the slider to be pulled away from the disk surface with a zero slider load, which in turn can reduce variations of the floating height of the slider and damages to the disk caused when the slider contacts the disk (because of the zero load). 
     Further, changing inclination angles θ 1 , θ 2  and lengths L 1 , L 2  of the inclined portions of the first and second ramps allows the loading/unloading conditions of the suspension and the slider to be controlled desirably. For example, if the inclination angle θ 2  of the second ramp is reduced, the slider can be loaded or unloaded slowly onto or from the disk surface. This in turn can reduce damages to the slider and the disk surface that may be caused during the loading/unloading operation. 
     In the conventional magnetic head support mechanism, as shown in FIG. 6A, there is one tab  24  at the tip of the support mechanism and one ramp  5 . Hence, in the case of the negative pressure slider, even when the tab  24  is lifted by the ramp  5 , the slider  40  remains on the disk surface due to the negative pressure. The suspension  2  on the other hand is pulled away from the disk surface, so the flexible finger portion  26  of the gimbals  31  deforms, giving rise to a problem that the slider  40  cannot be lifted stably. 
     In the present invention, as shown in FIG. 6B, the second tab  30  and the second ramp  53  combine to prevent the slider  40  from remaining on the disk surface and deforming the flexible finger portion  26  during unloading even when the negative pressure slider is used. 
     To eliminate the drawback of the conventional support mechanism, it may be possible to adopt a construction that has a hook extending upward from the slider mounting portion to above the load beam. When the load beam is pulled away from the disk surface by the tab, the hook engages the load beam and lifts the slider at the other end of the hook from the disk surface. As a result, the gimbals deformation problem does not occur. However, an impact test during operation (conducted with the slider floating over the rotating disk), which has gained importance in recent years, has found that impacts may vibrate the load beam and cause the hook to engage the load beam, disturbing the floating attitude of the slider, which may in turn cause damages to the disk. When the hook is not used on the other hand, such a problem is not likely to occur. 
     An impact tester as shown in FIG. 7A was used to determine an impact resistance limit acceleration and the test result is shown in FIG.  7 B. 
     Comparison of the impact resistance limit accelerations indicates, as shown in FIG. 7B, that the present invention improves the limit performance over the support mechanism using the hook. 
     A second embodiment of the present invention will be described by referring to FIG.  8 . In this embodiment the starting positions of the inclined portions of the first and second ramps are aligned (L 3  in FIG. 4C is set to 0) and the lengths of the ramps are set shorter. This enables a reduction in the size of the ramp, an increase in the data surface of the magnetic disk, and a reduction in the size of the magnetic disk drive. In this embodiment, too, the second tab and the second ramp combine to lift the slider away from the disk surface, preventing the gimbals from being damaged. 
     A third embodiment of the present invention will be described by referring to FIG.  9 . The point in which this embodiment differs from the first embodiment is that the second tab  30  is stepped toward the side of the slider&#39;s floating surface with respect to the slider mounting portion  29 . With this arrangement, it is possible to widen the gap between the first tab and the second tab, reducing the possibility of the two contacting each other and improving the productivity. This embodiment can also produce the effect similar to that of the first embodiment. 
     A fourth embodiment of the present invention will be described by referring to FIGS. 10A and 10B. 
     This embodiment differs from the first embodiment in that the first tab and the first ramp are eliminated and only the second tab and the second ramp are provided. Further, the load beam has a second pivot (dowel)  100  at the front end. In the normal floating state, this pivot  100  remains out of contact with the second tab of the gimbals with a predetermined small gap between them, as shown in FIG.  10 A. This gap is held at a magnitude such that they do not contact each other when the manufacturing tolerance is considered or when a variety of vibrations are generated during the operation of the disk drive. This gap is set in a range from about 10 μm to about 50 μm in this embodiment. The size of this gap, however, depends largely on the machining precision. 
     FIG. 10B shows the second pivot in contact with the second tab  30  during loading/unloading. When the second tab rides over the second ramp, the front end of the second tab inclines and deforms causing the second tab  30  to contact the second pivot. As a result, the pressing force from the second ramp is transmitted directly to the second pivot of the load beam, without being passed to the gimbals. Therefore the load beam can also be loaded/unloaded by only the second ramp. 
     This embodiment can thus produce the similar effect to that of the first embodiment. Because the first tab and the second tab can be eliminated, the construction can be made simpler than that of the first embodiment. The second pivot  100  of this embodiment can be formed by pressing, simultaneously with the pivot  23 , so additional manufacturing burden is small. 
     With this invention, if the magnetic head support mechanism for loading/unloading uses a negative pressure slider, the second tab provided to the gimbals and the second ramp can prevent deformation of the gimbals and thus a highly reliable magnetic head support mechanism can be provided. Further, the loading/unloading conditions of the load beam and the slider can be changed freely and independently of each other. This makes it possible to realize a loading/unloading condition suited to a particular purpose.