Web transport control circuit
AssigneeDennison Manufacturing Company
InventorsWay D. Woo, William Steddom
Life of this patent
Estimating the term…
Abstract
Method and apparatus is disclosed for driving the take up and supply spools of a web transport system. The apparatus includes a pair of direct current motors, one for each spool, and a circuit for regulating the current in the two motors. The circuit senses the counter EMF across the takeup motor, and accordingly controls the current in the supply motor, in order to apply a proper dragging torque to the supply spool. In the event of a loss of power to the web transport, the two spools are brought to a stop in a controlled manner by electronic means.
Claims10
Improved apparatus for controlling the transport of a web between two spools, of the type including a driving spool, rotated by a driving motor, and a driven spool, to which a drag is applied by a driven motor, and means for energizing the motors, wherein the web is transported from the driven spool to the driving spool, in which the improvement comprises improved apparatus for controlling the angular speed of the spool rotations comprising:
- means for detecting a back electromotive force ("back EMF signal") produced by the driving motor during rotation of the driving spool;
- further detecting means for detecting a back EMF signal produced by the driven motor during rotation of the driven spool;
- a feedback signal path containing a resistor and diode in parallel for routing the back EMF signal produced by the driving motor back to that motor, wherein the diode blocks the back EMF signal produced by the driving motor;
- and
- a further feedback signal path containing a resistor and diode in parallel for routing the back EMF signal produced by the driven motor back to that motor, wherein the diode passes the back EMF signal produced by the driven motor.
Improved apparatus for transporting a web between two spools, of the type including a driving spool, rotated by a driving motor, and a driven spool, to which a drag is applied by a driven motor, wherein the web is transported from the driven spool to the driving spool and induces a rotation of the driven spool, in which the improvement comprises apparatus for regulating the tension of the web during transport comprising:
- means for energizing said driving motor;
- means for detecting transient signals produced by said driving motor during its rotation of said driving spool;
- and
- means responsive to the detected transient signals for regulating an excitation of said driven motor to maintain a prescribed tension in said web,
- wherein a signal path is included between said motors having an intermediate ground connection, thereby establishing a reference level for the regulating means.
Improved apparatus for transporting a web between two spools, of the type including a driving spool, rotated by a driving motor, and a driven spool, to which a drag is applied by a driven motor, wherein the web is transported from the driven spool to the driving spool and induces a rotation of the driven spool, in which the improvement comprises apparatus for regulating the tension of the web during transport comprising:
- means for energizing said driving motor;
- means for detecting transient signals produced by said driving motor during its rotation of said driving spool, including a Zener diode to approximate said transient signals;
- and
- means responsive to the detected transient signals for regulating an excitation of said driven motor to maintain a prescribed tension in said web.
Improved apparatus for transporting a web between two spools, of the type including a driving spool, rotated by a driving motor, and a driven spool, to which a drag is applied by a driven motor, wherein the web is transported from the driven spool to the driving spool and induces a rotation of the driven spool, in which the improvement comprises apparatus for regulating the tension of the web during transport comprising:
- means for energizing said driving motor;
- means for detecting transient signals produced by said driving motor during its rotation of said driving spool;
- means responsive to the detected transient signals for regulating an excitation of said driven motor to maintain a prescribed tension in said web;
- and
- means for controlling the angular speed of spool rotation, comprising:
- alternative detecting means for detecting a back electromotive force ("back EMF signal") produced by the driving motor during rotation of the driving spool;
- further detecting means for detecting a back EMF signal produced by the driven motor during rotation to the driven spool;
- a feedback signal path for routing the back EMF signal produced by the driven motor during rotation to the driven spool;
- a feedback signal path for routing the back EMF signal produced by the driving motor back to that motor, in a manner tending to reduce its speed of rotation;
- and
- a further feedback signal path for routing the back EMF signal produced by the driven motor back to that motor, in a manner tending to reduce its speed.
Dependencies are inferred from the claim text.