CENTER SUPPORTED ACTUATOR CARRIAGE ASSEMBLY

Abstract: A carriage assembly (1) for use in optical recording apparatus wherein the carriage body (8) to which the sensing means are attached is mounted to the assembly guide (rails 6, 7) through the combined center of mass (29) of the carriage body and sensing means so that upon activation, the apparatus is not subjected to bending or torsional stresses which cause the tangential and radial tracking errors. By placing the center of mass in the plane of the bearing support, the carriage body can be constructed of lighter weight materials thus allowing for more rapid and precise assembly movement.

Description: CENTER SUPPORTED ACTUATOR CARRIAGE ASSEMBLY BACKGROUND OF THE INVENTION 1. Field of Invention This invention relates to the field of transport mechanisms in data storage devices, and in particular, to the field of carriage assemblies for supporting and transporting data sensing elements in the data storage devices. 2. Description of the Prior Art In magnetic and optical disk data storage devices, it is necessary to rapidly move the data sensing head over the rotating disk in order to write or read digital data. In the prior art, the bi-directional movement of the head assembly is accomplished with attachment of the sensing device to a carriage assembly, which in turn is attached to the armature of a voice coil motor. The movement of the armature, and in turn the carriage assembly, is extremely rapid, in the order of miliseconds, therefore requiring a relatively low mass carriage assembly. In addition, the sensing means must be moved exceedingly small distances, on the order of microinches. Because such • rapid movements of the relatively large structure over relatively small distances, it is necessary, a high degree of stability be established in the carriage assembly. The carriage assembly should also have minimal mechanical resonances and mechanical friction in order to minimize radial tracking errors. The prior art has addressed this problem by constructing carriage bodies having desirable vibration characteristics, and by providing special undercarriage assemblies to minimize undesirable resonant vibrations. In U.S. Patent No. 3,838,455, issued to Barnard, September 24, 1974, wherein a carriage assembly is disclosed having the carriage body supported by roller bearings O PI WHO mounted on the bottom of the carriage body. One problem encountered in this design, is that the voice coil motor armature when attached to the carriage body, will not be acting through the center of the bearing support, thereby accentuating the bending and corresponding vibration of the carriage body during rapid acceleration and deceleration movements. - The present invention addresses this problem by providing for the mounting of the carriage body upon its supports in such a manner as to have the center of mass of the carriage assembly coincident with the plane through which the carriage assembly is supported by the carriage guides. This significantly reduces the bending forces to which the carriage assembly is subjected, thereby significantly reducing the generation of vibrations in the carriage body. The present invention is also an improvement over the prior art iri that the carriage body can be simply and inexpensively constructed. It is an object of this invention to provide a low mass carriage assembly for transmission of the reciprocating motion of a voice coil motor armature to a data sensing means in a disk information storage device. It is another object of this invention to minimize the vibration of the carriage assembly in a disk information storage device. It is still another object of this invention to minimize the radial tracking error of the data sensing means in a disk information storage device. it is yet a further object of this invention to minimize the tangential tracking error and movements normal to the disk surface of the data sensing means in a disk information storage device. It is still yet another object of this invention to provide a low cost carriage assembly for a disk information recording device. It is still yet a further object of this invention to provide an easily constructed carriage assembly for a disk information recording device. OMPI BRIEF SUMMARY OF THE INVENTION In the preferred embodiment of the present invention, a carriage assembly, a high mass base is provided to which is attached a pair of cylindrical guide rails or rods which support and guide the carriage body. The carriage body has mounted thereon, a plurality of roller or ball bearings, which cooperate to retain the carriage body on the guide rods and allow the free reciprocal movement of a carriage body along the support guide rods. Depending upon the mass and configuration of the sensing means attached to the front of the carriage body, the roller bearings are mounted such that the center of mass of the combined carriage body and data sensing means lies in a plane formed by the pair of support rails and thus in the same plane as the bearings. The center of force of the voice coil armature lies in the same plane. In this manner, no bending movement is applied to the carriage assembly as the carriage assembly is rapidly actuated back and forth along the support guide • rods. The rear of the carriage body is attached to the front face armature of the voice coil motor, said motor providing the reciprocal movement means in the data storage device. This entire assembly is located in the data storage device such that the data sensing means is able to translate in a radial direction over the information recording disk and is constrained against movements in all other directions. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective representation of the disassembled carriage and assemblies. FIG. 2 is a front view of the preferred embodiment with the back end of the carriage body attached to a voice coil motor armature, and the front end of the carriage body having a slider with a magnetic transducer attached thereto. FIG. 3 is a top view of the preferred embodiment of the disclosed invention, with the back end attached to the armature of a voice coil motor, and the front end having a slider with a magnetic transducer attached. FIG. 4 is a pictorial representation on an alternative embodiment having a cylindrical carriage body. FIGS. 5 and 6 are pictorial representations of alternative embodiments of the disclosed invention. FIG. 7 is a pictorial representation of an alternative embodiment of the disclosed invention having two optical heads attached thereto for sensing data on a disk having data on both sides of said disk. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a pictorial representation of the disclosed invention in a disassembled configuration. The carriage-rail assembly 1 is composed of the carriage body 8 and the rail assembly 5. The carriage body 8 is attached to the armature 2 of a voice coil motor 3 by means of mounting holes 4 in the end of the armature 2. The rail assembly 5 is comprised of, a U-shaped base 28 and a pair of support rails 6 and J. The support rails 6 and 7, are mounted on the upper legs 9 and 10, of the U-shaped base 28, on shoulders 11 and 12, which are located on the upper inner surface of the legs 9 and 10, such that the support rails 6 and 7 are horizontal and precisely parallel to each other. The support rails 6 and 7 are attached to the shoulders 11 and 12 through a plurality of holes 13 in the upper portion of the legs 9 and 10 and secured through threaded holes 14 in the rails 6 and 7 for that purpose, with a plurality of threaded bolts 15. The carriage body 8 is mounted on the support rails 9 and 10 by means of a plurality of roller bearings 16 which retain the carriage body 8 on the support base 28 allowing the carriage body 8 to reciprocate in a direction parallel to the axis of the support rails 9 and 10. The carriage body 8 is _ OMPI secured to the armature 2 by means of a connecting strut 17 which is bolted to the armature 2 through a plurality of holes 18 in the strut 17 for that purpose. The sensing means is secured to the front of the carriage body 8 through holes 19. As shown in FIG. 2, the roller bearings 16 are attached to the carriage body 8 such that the center of mass of the carriage body 8 and the data sensing means, in this drawing an air bearing slider assembly 20, lie in the first plane 21 formed by the parallel support rods 6 and 7. The center of force from the armature lies in this plane. In FIG. 2, a first x-Plane 21 is normal to the plane of the drawing. As shown in FIGS. 1 and 2, by having the center of mass 29i of the carriage body 8 coincident with the line 30 representing the force vector from the armature 2, and co-incident with the plane of support 21, deformation of the carriage body 8 resulting from the rapid acceleration and deceleration of the carriage body 8 is reduced. This in turn results in decreases radial and tangential errors in data sensing means with respect to the disk surface, particularly reducing the errors caused by the vibration of the carriage body 8 as resonant frequencies. In addition, because less bending and torsional stresses are placed on the carriage body 8, the carriage body 8 can be made of lighter weight material and more easily constructed. As shown in FIG. 2, the moving portion of the carriage-rail assembly 1 is symmetrical with respect to the first x-Plane 21 (normal to the plane of the drawing) and passing through the center of the assembly 1 in the X-direction 22, and with respect to a second y-Plane 23, which is normal to the plane of the drawing and passes through the center of the assembly 1 in the Y-direction 24. Having two axis of symmetry further reduces the off center-of-mass forces which would cause deformation of the carriage body 8 and the slider assembly 20.- The center of mass 31 of the slider assembly 20 is also coincident with the center of force 30 from the armature, O PI and the plane 21 of bearing supports 6 and 7. FIG. 3 shows a top vies of the disclosed invention showing the symmetrical nature of the carriage assembly and sensing assembly with respect to the 23 plane. FIG. 4 shows an alternative embodiment of the disclosed invention wherein the carriage body 8 is cylindrical in shape having a tapered nose 25 to which a slider assembly 20 (not shown) can be attached. In FIG. 4, the carriage body 8 has eight roller bearings 16 attached thereto. It should be noted that while the drawings disclose the use of either six or eight roller bearings 16, it is understood that any number of roller bearings may be used and that alternative means of mounting the carriage body 8 to the rails 6 and 7 for the free sliding translation of the carriage body 8 are contemplated by this disclosure. FIG. 5 shows the alternative embodiment of the disclosed invention wherein attached to the front of the carriage body 8 is an attachment 26 for connecting optical elements which transmit the light beams from the light source through to the disk surface. FIG. 6 shows the alternative embodiment wherein a dual slider configuration 27 is attached to the carriage body- 8. In this embodiment, the carriage-rail assembly is configured to translate the dual sliders assembly with respect to a two-sided disk or even between two disks. More than two sliders could be used (with more disks) also. As shown in FIGS. 6 and 7, this configuration is particularly well suited for use with devices having a moveable spindle for loading and unloading removable disks. In this mode, the simplicity of the present invention specifically increases the utility of the radial direction short stroke actuator in allowing the us of a smaller carriage body 8, and in allowing the manufacture of a lighter weight material carriage body 8. \. _-- . - ~ ~ In FIG. 7, a dual head 31 and 32 optical configuration is represented , for use with a removable optical di3k spindle assembly 33.

Claims: CLAIMS We claim: 1. A moveable carriage-rail assembly for supporting the transverse reciprocal movement of a digital data sensing means in a data storage device having a rotating disk information storage medium, comprising: a digital data sensing means, said sensing means fixedly attached to a carriage body for reciprocate radial translation over the rotating information disk surface; a means for actuating the reciprocating movement of the data sensing means over the data storage disk; a carriage body for transferring the reciprocating movement of the actuator means to the digital data sensing means; a guide means for supporting the longitudinal reciprocating movement of the carriage body through the center of mass of the moving portion of the carriage assembly. 2. A moveable carriage-rail assembly of claim 1 wherein the reciprocating movement actuator means is comprised of a linear motor having a armature coil deposed in said motor, said armature moving in a linear movement in response to varying current in said armature. 3. A moveable carriage-rail assembly of claim 1 wherein the guide means is comprised of: a support base, attached to the frame of the storage device, said base having a means for attachment support of guide rails to said base; a pair of guide rails, said rails fixedly mounted to the support base and mounted parallel to each other, andj a means for moveably mounting the carriage body to the guide supports such that the carriage body is free to reciprocate O PI upon the guide supports. 4. A moveable carriage-rail assembly of claim 3 wherein the base is further comprised of a U-shaped base having a horizontal bottom member which is fixedly mounted to the frame of the storage device, and a pair of vertical members, each vertical member having a shoulder on the upper inner edge for placement of the guide supports, said shoulders each having the longitudinal axis horizontally oriented and parallel ' to each other. 5. A moveable carriage-rail assembly of claim 3 wherein the means for moveably mounting the carriage body to the guide supports is comprised of a plurality of roller ' ball bearings, rotatably attached to the carriage body such that the center of mass of the combined body and sensing means, lies in the plane formed by the parallel rails. 6. A moveable carriage-rail assembly of claim 5 further comprising mounting said bearings such that at least one bearing on each side oppositely mounted with respect to the rails in order that the body is firmly held to the rails and having only one degree of freedom is free to reciprocate only in a direction parallel to the longitudinal axis of the rails. 7. A moveable carriage-rail assembly of claim 6 wherein the body with the sensing means attached thereto is symmetrical with respect to a first vertical plane passing normal to longitudinal axis and through the- combined center of mass such that the combined body and sensing means have one degree of axial symmetry. 8. A moveable carriage-rail assembly of claim 5 wherein the body with the sensing means attached thereto is symmetrical with CVfFI . IPO respect to a second, horizontal plane passing through the combined center of mass such that the combined body and sensing means have one degree of axial symmetry. 9. A moveable carriage-rail assembly of claim 8, wherein the plane formed by the geometric centers of said carriage bearings is co-planar with said second horizontal plane. 10. A moveable carriage-rail assembly of claim 5 wherein the body with the sensing means attached thereto is symmetrical with respect to a first, vertical, plane and a second, horizontal, plane, both normal to the longitudinal axis, and both said first and second planes passing through the combined center of mass such that combined body and sensing means has two degrees of axial symmetry. 11. A moveable carriage-rail assembly of claim 1 wherein the data sensing means is comprised of an objective lens system for focusing a coherent light beam onto the surface of an optical recording disk and returning said beam after reflection from the disk surface. 12. A moveable carriage-rail assembly of claim 7 wherein the data sensing means is comprised of an objective lens system for focusing a coherent light beam onto the surface of an optical recording disk and returning said beam after reflection from the disk surface. 13. A moveable carriage-rail assembly of claim 1 wherein the data sensing means is comprised of a slider assembly and transducer for writing and sensing the data on a magnetically encoded information disk. O ?I 14. A moveable carriage-rail assembly of claim 1 wherein the data sensing means is comprised of a dual head slider and transducer assembly for writing and sensing the data on a two sided magnetically encoded information disk. 15. a moveable carriage-rail assembly of claim 10 wherein the data sensing means is comprised of a slider assembly and transducer for sensing the data on a magnetically encoded-information disk. 16. A moveable carriage-rail assembly of claim 1 wherein the data sensing means is comprised of a dual head optical assembly for writing and sensing the data on a two sided optically encoded disk.

Inventors: RICKERT DAVID W, WILKINSON RICHARD A JR, RICKERT, DAVID, W., WILKINSON, RICHARD, A., JR.
Applicants: STORAGE TECHNOLOGY PARTNERS, STORAGE TECHNOLOGY PARTNERS II
Application year: 1984
Main classification: G11B5
IPC codes: G11B5, G11B7, G11B21