This application relates generally to disc drives and more particularly to a stacked actuator arm assembly in a disc drive. Further, the stacked actuator arm assembly has a printed circuit card mounted on a single stacked element of the stacked actuator arm assembly.
A typical disc drive includes a base to which various components of the disc drive are mounted. The components include a spindle motor, which rotates one or more discs at a constant high speed. Information is written to and read from tracks on the discs through the use of a stacked actuator arm assembly, which rotates during a seek operation about a bearing shaft assembly positioned adjacent the discs. The stacked actuator arm assembly may include a plurality of actuator arms, which extend towards the discs, with one or more head suspension assemblies extending from each of the actuator arms. Each head suspension assembly includes a flexure or load beam and a head mounted on a gimbal assembly at the distal end of the load beam. Each head includes an air bearing slider enabling the head to fly in close proximity above the corresponding surface of the associated disc. Head suspension assemblies are typically attached to the corresponding metallic actuator arms by a metallic spring member spot welded to the metallic load beams and to the metallic actuator arms. The spring member biases the head suspension assembly towards the surface of the disc.
During a seek operation, the track position of the heads is controlled through the use of a voice coil motor, which typically includes a coil attached to the stacked actuator arm assembly, as well as one or more permanent magnets, which establish a magnetic field in which the coil is immersed. Application of current to the coil causes the coil to move. As the coil moves, the stacked actuator arm assembly pivots about the bearing shaft assembly, and the heads are caused to move across the surfaces of the discs.
During the manufacture of a stacked actuator arm assembly it is most important that the number of subassemblies and parts be minimized to simplify the final automated build of the stacked actuator arm assembly. In the past the printed circuit card mounted on the stacked actuator arm assembly has been fastened to the assembly with one pin. This allowed the card to vibrate excessively during track seek moves of the stacked actuator arm assembly. What was needed was a mounting system for the card to reduce vibration by the card without increasing the number or complexity of subassemblies in the final build of the stacked actuator arm assembly.
In accordance with the present invention the above and other problems have been solved by a stacked actuator arm assembly having plural pin mounts and plural support members for a printed circuit card. Further, the plural pins and plural support mounts are part of a single stacked element of the stacked actuator arm assembly. The card is mounted on the stacked element and attached firmly thereto through at least two pins and two supports mounts. The printed circuit card and the single stacked element, to which it is attached, form a subassembly which facilitates final build of the stacked actuator arm assembly.
In another aspect of the invention the printed circuit card is mounted on the overmold spacer in the stacked actuator arm assembly. The overmold spacer has an overmold that carries the actuator coil which when energized rotates the stacked actuator arm assembly. The overmold also carries pins and support mounts for the printed circuit card in addition to the pins and support mounts on the spacer itself.
These and various other aspects and features as well as advantages which characterize the present invention will be apparent from a reading of the following detailed description and a review of the associated drawings.
A disc drive 100 constructed in accordance with a preferred embodiment of the present invention is shown in
During a seek operation, the track position of the heads 118 is controlled through the use of a voice coil motor 124, which typically includes a coil 126 attached to the actuator assembly 110, as well as one or more permanent magnets 128, which establish a magnetic field in which the coil 126 is immersed. Preferably, the coil 126 is formed as an integral part of a plastic mold extension—the overmold—of a spacer between actuator arms 114. The controlled application of current to the coil 126 causes magnetic interaction between the permanent magnet 128 and the coil 126 so that the coil 126 moves in accordance with the well known Lorentz relationship. As the coil 126 moves, the stacked actuator arm assembly 110 pivots about the bearing shaft assembly 112, and the heads 118 are caused to move across the surfaces of the discs 103.
A flex assembly 130 provides the requisite electrical connection paths for the stacked actuator arm assembly 110 while allowing pivotal movement of the actuator assembly 110 during operation. The flex assembly includes a printed circuit board 131 mounted on one side of the stack of actuator arms 114 and a flex cable 132. The mounting of the printed circuit board or card 131 is described in detail hereinafter. Head wires (not shown) are connected to the printed circuit board; the head wires are routed along the actuator arms 114 and the load beams 116 to the heads 118. The printed circuit board 131 preferably includes circuitry for controlling the write currents applied to the heads 118 during a write operation and a preamplifier for amplifying read signals generated by the heads 118 during a read operation. Additionally, the portion of the head wires that are routed along the actuator arms 114 are preferably a flex circuit attached to actuator arms 114 and load beams 116. The flex assembly also includes a flex cable 132 that extends from the circuit board 131 and terminates at a flex bracket 134. The flex bracket 134 communicates through the base deck 102 to a disc drive printed circuit board (not shown) mounted to the bottom side of the disc drive 100.
Referring now to
The stacked assembly is made up of four actuator arms 114 with spacers between the outer actuator arms and the inner actuator arms. The actuator arms and the spacers are stacked on sleeve or hub 150 of bearing shaft assembly 112 (
In addition to the nut 154 holding the stacked actuator arm assembly together, there are also provided two threaded pins, (bolts or screws) 158 (
The load beams 116 are attached to the actuator arms by spring members 162 which provide a spring force to load the heads 118 (
The stacked actuator arm assembly is completed by adding washer 152 to the stack and threading nut 154 onto the threads at the bottom of hub or sleeve 150. With all elements in the stack in proper alignment screws 158 will pass through holes in the arms and spacers and screw into threaded holes 160 in washer 152.
This embodiment of the invention provides three support mounts and two pins of attachment to securely mount the printed circuit card 131 on the overmold spacer and minimize vibration of the card during high frequency seek operations by the actuator arm. There could also be a pin in support mount 206 if three pins are desired. If only two pins are to be used, they might be placed in any two of the support mounts 206, 208 and 210.
It will be clear that the present invention is well adapted to attain the ends and advantages mentioned as well as those inherent therein. While a presently preferred embodiment has been described for purposes of this disclosure, various changes and modifications may be made which are well within the scope of the present invention. For example, many different locations for mounting pins and supports may be used to mount the printed circuit card on a spacer element in accordance with the present invention. Supports and pins might be added to a second spacer element for the purpose of mounting the printed circuit card on a stacked element other than the overmold spacer carrying the actuator coil. Also more than two pins might be used and two or more mounting supports might be used.
Numerous other changes may be made which will readily suggest themselves to those skilled in the art and which are encompassed in the spirit of the invention disclosed and as defined in the appended claims.