Offset print apparatus and methods

Patent metadata

Field	Value
Publication number	US-12162265-B2
Application number	US-201917255740-A
Country	US
Kind code	B2
Filing date	Feb 22, 2019
Priority date	Feb 22, 2019
Publication date	Dec 10, 2024
Grant date	Dec 10, 2024

Abstract

Offset print apparatus comprises a blanket arranged in a closed loop around a plurality of rollers. Each of the plurality of rollers is rotatable about a respective roller axis to support and convey the blanket around the closed loop. The plurality of rollers comprises: a primary steering roller rotatable about a primary roller axis and being pivotable about a primary steering axis perpendicular to the primary roller axis; and a secondary steering roller rotatable about a secondary roller axis and being pivotable about a secondary steering axis perpendicular to the secondary roller axis. The primary and secondary steering rollers are each independently pivotable. The offset print apparatus further comprises an actuator to actuate pivoting of the primary steering roller and the secondary steering roller.

First claim

The invention claimed is:

1. Offset print apparatus comprising a blanket arranged in a closed loop around a plurality of rollers, each of the plurality of rollers being rotatable about a respective roller axis to support and convey the blanket around the closed loop,
wherein the plurality of rollers comprises:
a primary steering roller rotatable about a primary roller axis and being pivotable about a primary steering axis perpendicular to the primary roller axis; and
a secondary steering roller rotatable about a secondary roller axis and being pivotable about a secondary steering axis perpendicular to the secondary roller axis;
wherein the primary and secondary steering rollers are each independently pivotable and the offset print apparatus further comprises an actuator to actuate pivoting of the primary steering roller and the secondary steering roller;
wherein the primary steering roller is configured to steer the blanket by twisting and the secondary steering roller is configured to steer the blanket by stretching.

2. Offset print apparatus according to claim 1 , comprising a controller to independently actuate the primary steering roller and the secondary steering roller to pivot about their respective steering axes to steer the blanket.

3. Offset print apparatus according to claim 2 , wherein the controller is to select one of the primary steering roller and the secondary steering roller to actuate for a steering operation based on a magnitude of a difference between a lateral position and/or skew of the blanket and a predetermined baseline position and/or skew corresponding to the steering operation;
wherein the controller is to select the primary steering roller for a steering operation when the magnitude of the difference exceeds a threshold; and
wherein the controller is to select the secondary steering roller for a steering operation when the magnitude of the difference is below the threshold.

4. Offset print apparatus according to claim 3 , wherein the controller is to control a printing agent applicator so that the printing agent applicator is disengaged for steering operations when the magnitude of the difference exceeds a threshold, and is engaged for steering operations when the magnitude of the difference is below the threshold.

5. Offset print apparatus according to claim 1 , wherein a wrap angle of the blanket around the primary steering roller is greater than a wrap angle of the blanket around the secondary steering roller.

6. Offset print apparatus according to claim 5 , wherein the wrap angle of the blanket around the primary steering roller is greater than about 45° and the wrap angle of the blanket around the secondary steering roller is less than about 45°.

7. Offset print apparatus according to claim 1 , wherein a diameter of the primary steering roller is greater than a diameter of the secondary steering roller.

8. Offset print apparatus according to claim 1 , wherein the primary steering axis is inclined by no more than 45° relative to a plane tangent to a portion of the primary steering roller wrapped by the blanket such that pivoting the primary steering roller introduces the twist to the blanket and the secondary steering axis is perpendicular or inclined by more than 45° relative to any plane tangent to a portion of the secondary steering roller wrapped by the blanket.

9. Offset print apparatus according to claim 1 , wherein the primary steering axis and the secondary steering axis are substantially perpendicular to one another.

10. Offset print apparatus according to claim 1 , wherein the primary steering roller is translatable along a tensioning direction normal to the primary roller axis to vary a tension in the blanket, and wherein the offset print apparatus comprises a tensioning actuator to drive translation of the primary steering roller in the tensioning direction.

11. Offset print apparatus according to claim 1 , wherein the offset print apparatus comprises a plurality of secondary steering rollers, each secondary steering roller being rotatable about a respective secondary roller axis and being pivotable about a respective secondary steering axis perpendicular to the corresponding secondary roller axis.

12. Offset print apparatus according to claim 2 further comprising a sensor to determine a lateral position and/or skew of the blanket, and wherein the controller is to independently actuate the primary steering roller and the secondary steering roller to pivot about their respective steering axes based on an output from the sensor.

13. A method of operating offset print apparatus of claim 1 comprising:
determining a difference between a lateral position and/or skew of the blanket and a predetermined baseline position and/or skew;
when a magnitude of the difference exceeds a threshold, causing the primary steering roller to pivot about the primary steering axis to adjust the position and/or skew of the blanket to bring the magnitude below the threshold; and subsequently,
when the magnitude of the difference is below the threshold, causing the secondary steering roller to pivot about the secondary steering axis to adjust the position and/or skew of the blanket while the primary roller axis of the primary steering roller remains static.

14. Offset print apparatus comprising a blanket arranged in a closed loop around a plurality of rollers, each of the plurality of rollers being rotatable about a respective roller axis to support and convey the blanket around the closed loop,
wherein the plurality of rollers comprises:
a primary steering roller rotatable about a primary roller axis and being pivotable about a primary steering axis perpendicular to the primary roller axis, the primary steering axis being inclined by no more than 45° relative to a plane tangent to a portion of the primary steering roller wrapped by the blanket such that pivoting the primary steering roller is configured to introduce twist to the blanket; and
a secondary steering roller rotatable about a secondary roller axis and being pivotable about a secondary steering axis perpendicular to the secondary roller axis, the secondary steering axis being perpendicular or inclined by more than 45° relative to any plane tangent to a portion of the secondary steering roller wrapped by the blanket such that the secondary steering roller is configured to introduce stretch to the blanket;
wherein the primary and secondary steering rollers are each independently pivotable and the offset print apparatus further comprises an actuator to actuate pivoting of the primary steering roller and the secondary steering roller.

Assignees

• Hewlett Packard Development Co

Inventors

• Seemann Ziv
• Unaeve Boris
• Barazani Avi
• Katz Israel

Classifications

• B41J2/01

  Ink jet · CPC title

• B41F17/007

  Use of printing belts · CPC title

• B41F16/00

  Transfer printing apparatus · CPC title

• B41J2002/012

  with intermediate transfer member · CPC title

• G03G15/1615

  relating to the driving mechanism for the intermediate support, e.g. gears, couplings, belt tensioning · CPC title