A roll sheet with a continuous sheet wound in a roll form is rotated in a forward direction to supply the sheet to a printing unit. A sensor whose output is changed in accordance with a distance between the sensor and the sheet is used. A rotation direction of the roll sheet is switched from an opposite direction to the forward direction on the basis of the output of the sensor during rotation of the roll sheet in the opposite direction.

A roll sheet with a continuous sheet wound in a roll form is rotated in a forward direction to supply the sheet to a printing unit. A sensor whose output is changed in accordance with a distance between the sensor and the sheet is used. A rotation direction of the roll sheet is switched from an opposite direction to the forward direction on the basis of the output of the sensor during rotation of the roll sheet in the opposite direction.

A roll sheet with a continuous sheet wound in a roll form is rotated in a forward direction to supply the sheet to a printing unit. A sensor whose output is changed in accordance with a distance between the sensor and the sheet is used. A rotation direction of the roll sheet is switched from an opposite direction to the forward direction on the basis of the output of the sensor during rotation of the roll sheet in the opposite direction.

A roll sheet with a continuous sheet wound in a roll form is rotated in a forward direction to supply the sheet to a printing unit. A sensor whose output is changed in accordance with a distance between the sensor and the sheet is used. A rotation direction of the roll sheet is switched from an opposite direction to the forward direction on the basis of the output of the sensor during rotation of the roll sheet in the opposite direction.

A printing apparatus includes: a main body; a cover; a pair of supporters including a movable supporter; a first urging member configured to urge the movable supporter in an approach direction; an engaging member movable between a separated position and an engaged position; and a second urging member configured to urge the engaging member toward the engaged position. When the cover is in an open state, the engaging member is located at the engaged position by an urging force of the second urging member so as to inhibit movement of the movable supporter in the approach direction. When the cover is in a closed state, the engaging member is located at the separated position against the urging force of the second urging member by contact of the cover with the engaging member so as not to inhibit the movement of the movable supporter in the approach direction.

A printing apparatus includes: a main body; a cover; a pair of supporters including a movable supporter; a first urging member configured to urge the movable supporter in an approach direction; an engaging member movable between a separated position and an engaged position; and a second urging member configured to urge the engaging member toward the engaged position. When the cover is in an open state, the engaging member is located at the engaged position by an urging force of the second urging member so as to inhibit movement of the movable supporter in the approach direction. When the cover is in a closed state, the engaging member is located at the separated position against the urging force of the second urging member by contact of the cover with the engaging member so as not to inhibit the movement of the movable supporter in the approach direction.

A printing system and a method for printing a plurality of images on a first web and on a second web are disclosed. The printing system includes a print head, a feed unit for feeding both the first web and the second web simultaneously to the print head in a feed direction relative the print head, a wrap up unit for wrapping up both the first web and the second web simultaneously to form a first output roll and a second output roll respectively, a user interface configured to set a printing arrangement of the plurality of images on the first web and the second web and to input the print head, the feed unit and the wrap up unit for performing printing according to the printing arrangement by ejecting marking material on the respective webs. The printing system includes a prediction module for predicting a first diameter of the first output roll and a second diameter of the second output roll based on the printing arrangement. The prediction module is configured to establish a difference of the predicted first diameter and the predicted second diameter, and to provide to the user interface a warning when the established difference is larger than a predetermined diameter difference threshold.

A roll sheet with a continuous sheet wound in a roll form is rotated in a forward direction to supply the sheet to a printing unit. A sensor whose output is changed in accordance with a distance between the sensor and the sheet is used. A rotation direction of the roll sheet is switched from an opposite direction to the forward direction on the basis of the output of the sensor during rotation of the roll sheet in the opposite direction.

A roll sheet with a continuous sheet wound in a roll form is rotated in a forward direction to supply the sheet to a printing unit. A sensor whose output is changed in accordance with a distance between the sensor and the sheet is used. A rotation direction of the roll sheet is switched from an opposite direction to the forward direction on the basis of the output of the sensor during rotation of the roll sheet in the opposite direction.

A feeding unit for feeding a plastic film in packaging machines for wrapping paper rolls, including: a unit for unwinding the film from a reel; a cutting device adapted to cut the film transversely; a transfer device including, on the right and on the left side of the feeding unit, drive belts configured for engaging the upper and lower faces of the film; and a positioning device including, on the right and on the left side of the unit, a predetermined number of drive belts configured for engaging the upper and lower faces of the film. On each side of the feeding unit, the transfer device comprises two pairs of belts. On each side of the feeding unit, the positioning device comprises a third pair of belts. The three pairs of belts are actuated by independent actuators.