Patent Application
20080037159
For a fuller understanding of the nature and advantages of the present invention as well as the preferred mode of use, reference should be made to the following detailed description read in conjunction with the accompanying drawings.
Prior Art
Prior Art
The following description is the best mode presently contemplated for carrying out the present invention. This description is made for the purpose of illustrating the general principles of the present invention and is not meant to limit the inventive concepts claimed herein. Further, particular features described herein can be used in combination with other described features in each and any of the various possible combinations and permutations.
In the drawings like and equivalent elements are numbered the same throughout the various figures.
The embodiments described below disclose a new tape guide assembly used in conjunction with single or multiple tape supports. This invention eliminates the space restrictions of the conventional approach and so enables low cost and simpler head fabrication, and at the same time effectively reduces the amplitude of sporadic lateral transients.
In use, the tape 306 is threaded around the roller guide 304 and the supports 310, 312. Suitable threading mechanisms are known in the art, and may include or be a variant of the threading mechanisms such as those used in Video Cassette Recorder (VCR) machines or Linear Tape Open (LTO) machines. The head 314 is placed in contact with the tape 306 at a desired depth in order to achieve about a preferred wrap angle of the tape 306 relative to the head 314. In preferred embodiments, the head 314 contacts the data surface in the short span adjacent the support (in a single support embodiment) or between the supports 310, 312 (as shown). See also
As the roller guide 304 rotates, the backside of the tape 306 contacts the roller guide 304 and the tape 306 is carried across the head 314. As noted above, tape skew during reading or writing is undesirable. The present invention minimizes tape lateral motion because the tape 306 is anchored down to the roller guide 304. This in turn reduces skew.
The outer surface of the roller guide 304 may be textured. This enhances the sliding friction between tape 306 and roller guide 304, which is important for limiting sporadic and other lateral transients. In one embodiment, the outer surface of the roller guide 304 has grooves extending circumferentially therealong. Other illustrative texturing include cross hatching, raised regions, etc. The texturing, can be uniform or nonuniform along the outer surface of the roller guide 304.
As mentioned above, the back coat of the tape 306 is typically intentionally made rough to help it roll up on the reel without excess air build up between wraps on the reel. This roughness also enhances the anchoring of the tape 306 to the roller guide 304.
The supports 310, 312 are mounted very close to, or optionally in contact with, the associated roller guide 304. The supports 310, 312 are preferably rigid, smooth and properly contoured and accurately positioned relative to the roller guide 304.
The supports 310, 312 may have any of various shapes. For example, the supports 310, 312 may have a rounded shape profile, e.g. such as a semicircle, or more preferably, having a shape about conforming to a portion of a Cornu spiral, as shown. Such shapes are believed to minimize tape-induced wear.
In a preferred embodiment, the supports 310, 312 have a shape profile that enables an air bearing to form between the supports 310, 312 and the tape 306 to eliminate wear due to streaming tape. To further minimize wear, the supports 310, 312 may be constructed of a hard, wear resistant ceramic, such as AlTiC. Other suitable materials include hard metals such as stainless steel, etc.
In embodiments where the supports are rounded, the smaller the radius of curvature of the supports 310, 312, the more likely the tape 306 is to come into rubbing contact on the supports. Thus, a preferred minimum radius of the supports 310, 312 is about 5 mm for a tape having a thickness of about 5-25 microns.
A short span between the supports 310, 312 is preferred, as a short span tends to minimize flutter and other periodic and aperiodic disturbances of the tape 306 relative to the head 314. An illustrative span is between about 0.5 and about 10 mm.
The tape bearing surface of the head 314 faces the roller guide 304. Because the tape 306 is positioned between the head 314 and roller guide 304, there is plenty of room for the head, cables, etc.
The design of the head 314 is not critical. For instance, the head 314 can have a flat tape bearing surface, rounded tape bearing surface, and combinations thereof. For a head having a flat contour tape bearing surface, an illustrative wrap angle of the tape relative to the tape bearing surface is between about 0.8 and about 1.0 degrees.
The actuator 316 can be any type of actuator. For example, the actuator 316 may include a coarse actuator, a fine actuator, or both. The head/actuator assembly pivots down in the drawing to enable loading and unloading of the tape 306.
One skilled in the art will appreciate that the dimensions given above and other places herein are presented by way of example only and can be made larger or smaller per the design and fabrication constraints, performance considerations, etc.
Any of the above embodiments or combinations of portions thereof can also be applied to any type of tape head and magnetic tape recording systems, both known and yet to be invented. For example, the teachings herein are easily adaptable to interleaved heads, which typically include opposing modules each having an array of alternating readers and writers configured to provide read-while-write capability.
As shown, a tape supply reel 320 and a take-up reel 321 are provided to support a tape 306. These may form part of a removable cassette and are not necessarily part of the system. A guide assembly 302 guides the tape 306 across a preferably bidirectional tape head 314. Such tape head 314 is in turn coupled to a controller assembly 328 via a connector cable 330. The controller 328, in turn, controls head functions such as servo following, write bursts, read functions, etc. An actuator 316 controls position of the head 314 relative to the tape 306, and may operate under control of the controller.
A tape drive, such as that illustrated in
While various embodiments have been described above, it should be understood that they, have been presented by way of example only, and not limitation. Thus, the breadth and scope of a preferred embodiment should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.
