Magnetic head arm assembly

DETAILED DESCRIPTION Although the need for effective damping of out-of-plane resonances of head support arms has been recognized in the prior art, the various solutions proposed, that involve friction damping or constrained layer damping in a bending mode, have had a major structural impact on the support arm.
Furthermore neither of these methods of damping is as effective as shear damping.
According to the present invention, there is provided a head support arm for a disk file adapted to support a transducing head at one end and adapted at the other end to be mounted on a positioning apparatus in cantilever fashion, the arm comprising a relatively rigid beam structure of flattened cross-section defining a plane therethrough, which structure is susceptible to out-of-plane resonances, and damping means to damp said resonances, characterized in that the damping means comprises a relatively rigid sidebar located alongside one longitudinally extending edge of the beam structure, and a layer of relatively compliant damping material providing a mechanical connection between the sidebar and the beam structure whereby out-of-plane resonances of the beam structure are damped by shear of the damping material as a result of relative motion between the beam and sidebar.
By employment of shear damping, out-of-plane resonances of the beam structure are very effectively damped in a manner which does not alter the main structure of the support arm.
This type of damping is most effective if the orientation of the layer of damping material is normal to the plane of the beam structure.
Effectiveness is also increased if sidebars and layers of damping material are employed on both sides of the beam structure.
The preferred damping material is a layer of double sided adhesive tape, specifically a polyester backing membrane with an acrylic adhesive.
This bonds to the sidebar and to the beam structure, thus providing a mechanical connection between them.
Other materials have also been tried such as a simple layer of adhesive to bond the sidebar and arm directly together