A sheet feeding device includes a drive unit that rotates a roll of a wound sheet in a first direction and in a second direction, a sensor having an output which changes according to a distance between a detecting position facing a peripheral surface of the roll and the peripheral surface of the roll, and a control unit that determines an amplification factor of the sensor on the basis of data. The data is acquired by changing the amplification factor while the roll is rotated once in the second direction and includes a plurality of the output value acquired at different rotation angles.

In one example, a device for unwinding or winding multiple rolls of print substrate includes multiple spindles each to hold a roll of print substrate and a differential operatively connected to one end of each spindle. The spindles are aligned with one another lengthwise along a spindle axis and the differential is to output torque along a differential axis offset from the spindle axis to turn the spindles on the first axis.

A medium transport method, which is performed by a medium transport device having a transport unit which includes rollers that can pinch a medium and which transports the medium, includes inserting the medium to a predetermined position, pressing a side end portion of the medium against a side surface guide, and pinching the medium with the rollers, and transports the medium.

An expansible chuck for holding hollow cylindrical cores used for winding and unwinding sheet material. A portion of the chuck body nearest the flange is stepped up so that the diameter of the chuck near the flange is slightly larger than the diameter of the rest of the chuck. The stepped up portion centers the chuck within the core which helps the expanding elements to uniformly grip the core.

In one example, a device for unwinding or winding multiple rolls of print substrate includes multiple spindles each to hold a roll of print substrate and a differential operatively connected to one end of each spindle. The spindles are aligned with one another lengthwise along a spindle axis and the differential is to output torque along a differential axis offset from the spindle axis to turn the spindles on the first axis.

An expansible chuck for holding hollow cylindrical cores used for winding and unwinding sheet material. A portion of the chuck body nearest the flange is stepped up so that the diameter of the chuck near the flange is slightly larger than the diameter of the rest of the chuck. The stepped up portion centers the chuck within the core which helps the expanding elements to uniformly grip the core.

An apparatus to launch, retrieve, and store a recreational floating mat is described. The apparatus can provide the advantages of helping to ease the potential difficulties associated with launching, retrieving and storing recreational floating mats from dock side, pool side or from a floating vessel such as a boat or floating dock.

In one example, a device for unwinding or winding multiple rolls of print substrate includes multiple spindles each to hold a roll of print substrate and a differential operatively connected to one end of each spindle. The spindles are aligned with one another lengthwise along a spindle axis and the differential is to output torque along a differential axis offset from the spindle axis to turn the spindles on the first axis.

An expansible chuck for holding hollow cylindrical cores used for winding and unwinding sheet material. A portion of the chuck body nearest the flange is stepped up so that the diameter of the chuck near the flange is slightly larger than the diameter of the rest of the chuck. The stepped up portion centers the chuck within the core which helps the expanding elements to uniformly grip the core.

In one example, a device for unwinding or winding multiple rolls of print substrate includes multiple spindles each to hold a roll of print substrate and a differential operatively connected to one end of each spindle. The spindles are aligned with one another lengthwise along a spindle axis and the differential is to output torque along a differential axis offset from the spindle axis to turn the spindles on the first axis.