[Operating method and changer for optical module/printer module system]

A changer for driving a first module or a second module, the changer comprising:

• a roller having at least a latching element for latching with either the first module or the second module, wherein the roller further includes a first spiral groove on a side surface of the roller and the first spiral groove spirals around the central axis of the roller such that depth of the first spiral groove increases gradually, and the roller also includes a second spiral groove on another side surface of the roller and the second spiral groove spirals around the central axis of the roller such that depth of the second spiral groove increases gradually;
• a first lever rod for dipping into the first spiral groove and pressing against the bottom surface of the first spiral groove;
• and
• a second lever rod for dipping into the second spiral groove and pressing against the bottom surface of the second spiral groove.

A method of operating a multi-module system that uses a changer to drive either a first module or a second module, the method comprising the steps of:

• step one:
• providing a changer having:
• a first lever rod;
• a second lever rod;
• a roller having a latching element, wherein the roller has a first spiral groove on a side surface of the roller and the first spiral groove spirals around the central axis of the roller such that depth of the first spiral groove increases gradually, and the roller also has a second spiral groove on the side surface of the roller and the second spiral groove spirals around the central axis of the roller such that depth of the second spiral groove increases gradually, depth of the first spiral groove increases in a direction opposite to the second spiral groove, the roller travels in a straight line, the first lever rod and the second lever rod are positioned at the same end of the traveling path of the roller, and the roller further includes a latching element attached to the perimeter surface of the roller;
• wherein if the latching element on the roller of the changer engages with the first module initially, the changer is able to drive the first module;
• step two:
• the roller moves to one end of its traveling path close to the first lever rod;
• step three:
• the first lever rod dips into the first spiral groove and presses against the bottom surface of the first spiral groove so that the roller rotates, the latching element on the roller detaches from the first module and re-engages with the second module;
• step four:
• the roller moves and pulls the second module along the traveling path of the roller;
• step five:
• the roller moves to another end of the traveling path of the roller close to the second lever rod;
• step six:
• the second lever rod dips into the second spiral groove and presses against the bottom surface of the second spiral groove so that the roller rotates, the latching element on the roller detaches from the second module and re-engages with the first module;
• and
• step seven:
• the roller moves and pull the first module along the traveling path of the roller.

A method of operating a multi-module system that uses a changer to drive either a first module or a second module, the method comprising the steps of:

• step one:
• providing a changer having:
• a first lever rod;
• a second lever rod;
• a roller having a latching element, wherein the roller has a first side surface and a corresponding second side surface, the roller also has a first spiral groove and a second spiral groove, the first spiral groove is on the first side surface of the roller and spirals around the central axis of the roller such that depth of the first spiral groove increases gradually, the second spiral groove is on the second side surface of the roller and spirals around the central axis of the roller such that depth of the second spiral groove increases gradually, the roller travels in a straight line, the first lever rod and the second lever rod are positioned at the opposite end of the traveling path of the roller, and the roller further includes a first latching element, a second latching element and a third latching element attached to the perimeter surface of the roller;
• wherein if the first latching element on the roller of the changer engages with the first module initially, the changer is able to drive the first module;
• step two:
• the roller moves to one end of its traveling path close to the first lever rod;
• step three:
• the first lever rod dips into the first spiral groove and presses against the bottom surface of the first spiral groove so that the roller rotates in a first direction, the first latching element on the roller detaches from the first module and the second latching element re-engages with the first module;
• step four:
• the roller moves to another end of its traveling path close to the second lever rod;
• step five:
• the second lever rod dips into the second spiral groove and presses against the bottom surface of the second spiral groove so that the roller rotates in a second direction just opposite to the first direction, the second latching element on the roller detaches from the first module and the third latching element on the roller re-engages with the second module;
• step six:
• the roller moves and pulls the second module along the traveling path of the roller;
• step seven:
• the roller moves to another end of its traveling path close to the second lever rod;
• step eight:
• the second lever rod dips into the second spiral groove and presses against the bottom surface of the second spiral groove so that the roller rotates in the second direction, the third latching element of the roller detaches from the second module and the first latching element of the roller re-engages with the first module;
• and
• step nine:
• the roller moves and pulls the first module along the traveling path of the roller.