Printing cylinder positioning device and method

A rotatable printing cylinder positioning device, comprising:

• drive means for rotating the cylinder about a cylinder axis at a relatively high speed and for rotating the cylinder about the cylinder axis at a relatively low speed;
• sensor means for detecting rotational positions of the cylinder and for providing a signal which varies in response to detected rotational positions of the cylinder;
• target means for exciting said sensor means;
• and
• control means for controlling said drive means in response to the signal from said sensor means including means for controlling said drive means to rotate the cylinder at the relatively high speed until the cylinder reaches a first rotational position, for controlling said drive means to rotate the cylinder at the relatively low speed from the first rotational position to a second rotational position, and for controlling said drive means to cease rotation of the cylinder when the cylinder is at the second rotational position.

A rotatable printing cylinder positioning device, comprising:

• drive means for rotating the cylinder about a cylinder axis at a relatively high speed and for rotating the cylinder about the cylinder axis at a relatively low speed;
• sensor means for detecting rotational positions of the cylinder and for providing a signal which varies in response to detected rotational positions of the cylinder;
• target means for exciting said sensor means, said target means having first and second edges spaced along a segment of the cylinder, said sensor means being aligned with said first edge of said target means at a first rotational position of the cylinder and being aligned with said second edge of said target means at a second rotational position of the cylinder, the cylinder being rotatable through a rotational segment between the first and second positions;
• and
• control means for controlling said drive means in response to the signal from said sensor means including means for controlling said drive means to rotate the cylinder at the relatively high speed when the cylinder is not at a position on the rotational segment and until the cylinder reaches the first rotational position, for controlling said drive means to rotate the cylinder at the relatively low speed when the cylinder is located at a position on the rotational segment and until the cylinder is at the second rotational position, and for controlling said drive means to cease rotation of the cylinder when the cylinder is at the second rotational position.