Servo system

In combination for operating upon a medium having stretchable characteristics to vary the tension in the medium,

• a guide surface,
• means for providing a source for the medium,
• means for providing a receptacle for the medium,
• means for driving the medium from the source to the receptacle,
• means for passing the medium over the guide surface during the movement of the medium from the source to the receptacle,
• means for producing a variable fluid pressure between the medium and the guide surface sufficient to separate the medium from the guide surface, and
• means disposed relative to the guide surface for regulating the tension of the medium in accordance with the variations in the fluid pressure to regulate the separation between the medium and the guide surface,
• there being an image on the medium,
• the image on the medium being in magnetic form and the medium being a master tape and the image on the master tape being transferred to a slave tape,
• a pinch roller disposed after the guide surface in the direction of movement of the master tape, and
• a capstan disposed in abutting relationship to the pinch roller for receiving the slave tape to provide a transfer of the magnetic information on the master tape to the slave tape.

In combination for operating upon a medium having stretchable characteristics to vary the tension of the medium, the medium having a particular product of medium width, medium thickness and Youngs modulus,

• first means for holding the medium,
• second means for holding the medium,
• third means for driving the medium from the first means to the second means,
• guide means having a peripheral surface defining a segment of a cylinder,
• fourth means for maintaining the medium at a variable distance from the periphery of the guide means, and
• fifth means for regulating the tension of the medium in accordance with the particular product of the width, the thickness and the Youngs modulus of the medium and in accordance with the fourth means and the variation in the distance of the medium from the periphery of the guide means.

A method of regulating the tension on a stretchable medium, including the steps of:

• providing a medium extending continuously in a longitudinal direction and having first and second spaced and parallel surfaces and having a width and a thickness and a Youngs modulus and having a particular product of the width, thickness and Youngs modulus to provide the medium with a particular strain when the medium is subjected to a first force on the medium in a direction substantially parallel to the first surface of the medium, the medium having properties of becoming stretched in accordance with the stress imposed upon the medium,
• providing a second variable force on the first surface of the medium in directions substantially perpendicular to the first surface of the medium,
• providing a third retarding force on the medium substantially in the direction opposite to the direction of the first force,
• varying the third retarding force on the medium in accordance with the second force on the first surface of the medium and the particular product of the width, thickness and Youngs modulus of the medium to obtain a regulation of the tension of the medium,
• providing a movement of the medium in a particular direction past the position at which the third retarding force is regulated.

In combination for operating upon a medium having stretchable characteristics to vary the tension of the medium, the medium having a particular product of medium width, medium thickness and Youngs modulus,

• first means for holding the medium,
• second means disposed in spaced relationship to the first means for holding the medium,
• third means for driving the medium from the first means to the second means,
• guide means having a peripheral surface, the guide means being disposed between the first means and the second means for receiving the medium on the peripheral surface of the guide means during the movement of the medium from the first means to the second means,
• fourth means for producing a vacuum on a first portion of the peripheral surface of the guide means,
• fifth means for producing a pneumatic force on a second portion of the peripheral surface of the guide means, and
• sixth means for varying the vacuum from the fourth means in accordance with the product of the width, thickness and Youngs modulus of the medium and in accordance with variations in the separation between the medium and the peripheral surface of the guide means at the second positions on the peripheral surface of the guide means to maintain such separation at a particular value.

In a method of operating upon a medium having stretchable characteristics to vary the tension of the medium, the medium having a particular product of medium width, medium thickness and Youngs modulus, the steps of:

• providing a guide with a peripheral surface,
• moving the medium along the peripheral surface,
• applying a vacuum force to a first portion of the peripheral surface on the guide,
• applying a pneumatic force to a second portion of the peripheral surface on the guide, and
• varying the vacuum force at the first portion of the peripheral surface on the guide in response to variations in the separation between the medium and the peripheral surface at the second portion of the peripheral surface and in accordance with the particular product of the width, thickness and Youngs modulus of the medium to regulate at a particular value the separation between the medium and the peripheral surface at the second portion of the peripheral surface.