Contact sheet recording with a self-acting negative air bearing

A flat head and a tape transport arrangement impart a wrap angle to the tape at the upstream corner of the head. The wrap angle, corner sharpness and tape stiffness are sufficient to cause a moving tape to form a hollow bump at the upstream corner, thereby creating a hollow into which entrained air can expand, causing a subambient pressure within and downstream of the bump. This pressure keeps the tape in contact with the head. It is created without the need for a groove or complex pressure relief slot(s). No contact pressure arises at the signal exchange site due to media wrap. The highest contact pressures are developed at a wrapped upstream corner. For a tape drive, traveling in both forward and reverse, the wrap can be at both the upstream and downstream (which is the reverse upstream) corners. Heads that are not flat can also be used, if the wrap angle relative to a main surface is sufficient and not too large. The wrapped head can also be used with rotating media, such as disks (floppy and hard) and rotating heads, such as helical wound heads for video recording. Multiple flat tape bearing surfaces can be separated by grooves and/or angles. Each flat can carry heads along one or more gap lines. Multiple adjacent narrow tracks can thus be written for extreme high track density recording

Helical scan recording with a self-acting negative air bearing

A flat head and a tape transport arrangement impart a wrap angle to the tape at the upstream corner of the head. The wrap angle, corner sharpness and tape stiffness are sufficient to cause a moving tape to form a hollow bump at the upstream corner, thereby creating a hollow into which entrained air can expand, causing a subambient pressure within and downstream of the bump. This pressure keeps the tape in contact with the head. It is created without the need for a groove or complex pressure relief slot(s). No contact pressure arises at the signal exchange site due to media wrap. The highest contact pressures are developed at a wrapped upstream corner. For a tape drive, traveling in both forward and reverse, the wrap can be at both the upstream and downstream (which is the reverse upstream) corners. Heads that are not flat can also be used, if the wrap angle relative to a main surface is sufficient and not too large. The wrapped head can also be used with rotating media, such as disks (floppy and hard) and rotating heads, such as helical wound heads for video recording. Multiple flat tape bearing surfaces can be separated by grooves and/or angles. Each flat can carry heads along one or more gap lines. Multiple adjacent narrow tracks can thus be written for extreme high track density recording

Thin tape traction over a grooved roller

Traction between a thin, O(5 μm), tensioned tape and a grooved roller is studied. In the slow tape speed limit, tape contact over a grooved roller is studied analytically. A closed form relationship for the belt-wrap formula for grooved rollers is developed. In this range, air lubrication effects can be negligible and tape-to-roller contact is dominated by tape deflection in the lateral direction. At operational tape transport speeds, O(1-5 m/s), a relatively wide range of design parameters (groove width, land width) and device parameters (velocity and tension) were used to characterize the traction of a thin tape over a grooved roller. It was shown that air lubrication effects reduce the contact force, however the underlying effects of tape mechanics are not entirely eliminated. This work contributes to our understanding of traction mechanics of thin webs over grooved rollers, which has been understudied in the past, and helps in selecting design parameters for improved traction

General model of lateral web dynamics between two reels

A flexible web unavoidably deviates from its prescribed (linear) path during processing. The lateral web dynamics can be caused by tilt of rollers, web defects, off axis motion of the reels and other factors. In this work we present a generalized model of web transport between two reels, supported by numerous rollers. The mechanics of the web between the two reels is represented by a single partial differential equation, hence coupling of web-spans or lack thereof can be predicted. Web-to-roller interaction is modeled by assuming that tape sticks to the roller surface. The results of this general model are compared to the well-known model by Shelton and Reid (SR), which is applicable in the free span between two rollers. Good agreement between the present model and SR-model is found when the upstream free-span is stiff (or the downstream free-span is compliant), when the wrap angle is large and lateral bending rigidity is high. The present model otherwise predicts coupling of the mechanics of the free spans. The model is flexible to consider a variety of imperfections related to the web geometry and the path components. The lateral motion of a weaved web which is transported on a path with tilted rollers is simulated. The amplitude and the direction of the scatter wind due to this effect are predicted. In general the model shows that the coupling between the upstream and downstream web spans around a roller should not be neglected

Free vibration analysis of thin, tensioned, helically wrapped webs using Mindlin-Reissner finite element method

Free vibration analysis of a thin tensioned web, wrapped around a reverser was studied. The effect of helix angle was considered. The eigen-problem was formed using finite elements and solved numerically. Design parameters such as tension, radius of cylinder, wrap angle, width of the web, lengths of non-wrapped web and helical wrap angle were studied. It was seen that the free edges cause a frequency clustering of the lateral-modes about the dominant longitudinal-mode. It was also seen that the effectiveness of the plate-shell junction to act as a stiff support depends on problem parameters. Eigenmodes with same mode-shape numbers are observed in symmetric and anti-symmetric fashion about the center of the plate, for configurations with equally long unwrapped sections. The results also showed that the first natural frequency is reduced at large helical angles for the parameters studied

Manufacturing and performance evaluation of carbon nanotube-parylene sandwich thin films

Parylene-C, an inert and relatively mechanically strong polymer, which can be deposited in a conformal manner, is a promising substrate candidate for flexible electronics (Flextronics) devices. Parylene-CNT sandwich-films were fabricated by utilizing single-walled carbon nanotube (SWNT) layers sandwiched between two, 10 μm thick parylene layers. The device was fabricated using shadow mask technology and SWNT drop casting on top of the Parylene substrate. The electrical conductivity and mechanical properties of the samples were tested under tensile loading. The load-unload tests showed small change in electrical resistance (~1%) when applying a strain in the range 0 - 2%, with negligible hysterisis. The tensile test also showed ~32% increase in the elastic modulus (E) of the sandwich film, relative to pure parylene. Potential applications are in interconnects for flexible electronics devices, and strain sensors for biological systems