US 5,392,976 A · Servo system

Abstract

A master tape movable in a closed loop including a pinch roller transfers a mirror image to a slave tape movable in a closed loop including a capstan. A thermomagnetic layer on the slave tape has a Curie temperature above which magnetic information is destroyed and below which magnetic information can be recorded on such layer. The thermomagnetic layer is heated above the Curie temperature, thereby becoming lengthened by thermal expansion just before the slave tape reaches the capstan. A downstream portion of a peripheral surface, preferably defining a cylindrical segment, on a first guide receives a pressurized fluid for sensing the tape tension in accordance with the tape width, distance from the cylinder axis and fluid pressure. An upstream portion of the guide peripheral surface receives a vacuum adjustable to regulate tape tension in response to variations in the pressurized fluid pressure. In regulating the tape tension, the spacing between the slave tape and the peripheral surface at the downstream portion is controlled. The master tape is lengthened by a second guide having the same construction as the first guide to compensate for the slave tape lengthening by the heater and the first guide, thereby producing a mirror image on the slave tape after the slave tape has cooled to the ambient temperature. Each of the master and slave tapes has a particular product of the Youngs modulus, tape width and tape thickness to provide a controlled strain on such tape when the tension on such tape is regulated.

Claims43

Dependent claims

In combination for regulating the tension of a medium having a first surface and having a particular width, a particular thickness and a particular Youngs modulus and having a particular product of the width, thickness and Youngs modulus of the medium,

first means for subjecting the medium to a first force in a direction substantially parallel to the first surface of the medium,
second means for providing a variable force on the first surface of the medium in a direction substantially perpendicular to the first surface of the medium,
third means for providing a retarding force on the medium in a direction opposite to the direction of the first force,
fourth means responsive to the particular product of the width, thickness and Youngs modulus of the medium and responsive to variations in the force on the first surface of the medium in the direction substantially perpendicular to the first surface of the medium for varying the retarding force on the medium to regulate the tension of the medium, and
fifth means for providing a movement of the medium in a particular direction past the position at which the retarding force is varied and the variable force is provided.

2 more elements

In combination for operating upon a medium having stretchable characteristics to vary the tension in the medium, means for providing for a movement of the medium, guide means for providing a variable pneumatic force on the medium, means for regulating the tension of the medium in accordance with the variation in the pneumatic force on the medium, the guide means including a hollow interior and a peripheral surface and first orifices extending from the hollow interior to the peripheral surface of the guide means, the medium having a variable displacement from the surface of the guide means, the guide means further including means for providing for the production of a variable vacuum through the first orifices from the hollow interior to tension the medium in accordance with the variations in said vacuum, the guide means further including means for regulating the vacuum pressure through the first orifices in response to variations in the displacement of the medium from the peripheral surface of the guide means.

In combination for use with a medium having a particular width, thickness and Youngs modulus and a particular product of the particular width, thickness and Youngs modulus,

first means for providing a movement of the medium in a particular direction,
guide means having a peripheral surface and having orifices communicating with the peripheral surface, the guide means being disposed to receive the medium on its peripheral surface,
second means for producing on the medium through the orifices a variable pneumatic force to displace the medium from the peripheral surface of the guide means in response to the variations in such pneumatic force, and
third means for controlling the spacing between the medium and the peripheral surface of the guide means in response to the particular product of the width, thickness and Youngs modulus of the medium and to the variations in the pneumatic force on the medium.

1 more element

In combination for regulating the tension of a medium,

first means for driving the medium in a longitudinal direction,
a guide having a peripheral surface and having first orifices and second orifices displaced from the first orifices, the first and second orifices communicating with the peripheral surfaces, the second orifices being disposed upstream from the medium relative to the first orifices in the direction of movement of the medium,
first pneumatic means for producing a variable first pneumatic force on the medium through the first orifices in response to variations in the separation between the medium and the peripheral surface of the guide,
second pneumatic means for producing a second pneumatic force on the medium through the second orifices to retard the movement of the medium in the longitudinal direction, and
third means for pneumatically intercoupling the first and second pneumatic means to vary the second pneumatic force in response to the variations in the first pneumatic force for controlling the distance between the medium and the peripheral surface of the guide.

2 more elements

Dependencies are inferred from the claim text.

Servo system

Life of this patent

Servo system

Life of this patent

Abstract

Claims43