A method accurately determines internal stress in a film roll and prevents defects in the film roll. A film winding device includes a take-up roller and a winding tension adjustment device. A calculation device uses a winding equation in which a winding tension function is explicitly expressed, the winding tension function expressing a winding tension as a function of a radius of a core. The winding tension adjustment device controls winding tension in accordance with a winding tension distribution function calculated by the calculation device.

A method accurately determines internal stress in a film roll and prevents defects in the film roll. A film winding device includes a take-up roller and a winding tension adjustment device. A calculation device uses a winding equation in which a winding tension function is explicitly expressed, the winding tension function expressing a winding tension as a function of a radius of a core. The winding tension adjustment device controls winding tension in accordance with a winding tension distribution function calculated by the calculation device.

A medium feeding apparatus includes a feeding roller which feeds a medium unwound from a roll body around which the medium is wound, a roll motor which applies torque for rotating the roll body to the roll body, and a roll control portion which controls the roll motor at the time of a feeding operation based on effective tension calculated by acquiring a feeding amount of the medium fed at each of a plurality of acquiring timings included in a pre-feeding operation, which is a feeding operation performed in advance, acquiring tension applied to the medium between the roll body and the feeding roller between a plurality of the acquiring timings, and weighting a plurality of the acquired tensions with the corresponding feeding amount.

There is provided a medium feeding apparatus including a feeding roller that feeds a printing medium, a roll holding portion that holds a roll body on which the printing medium is wound, an intermediate roller that pulls out the printing medium from the roll body and feeds the printing medium on the feeding roller, a rotation amount detection portion that detects an amount of rotation of the intermediate roller and an amount of rotation of the roll body when the printing medium is fed by the intermediate roller, and a controller that calculates a roll diameter of the roll body based on the detected amount of rotation of the intermediate roller and the detected amount of rotation of the roll body.

The roller-to-roller conveyance control apparatus includes an amplitude target setting unit that sets an amplitude target value of the tension deviation; an adjustment execution command generation unit that provides a command to adjust the control gain; an adjustment manipulated-variable output unit that outputs an adjustment manipulated variable; a manipulated-variable amplitude determination unit that increases the amplitude of the adjustment manipulated variable until the amplitude of the tension deviation becomes larger than the amplitude target value; and a control-gain calculation device that calculates the control gain from the amplitude and the vibration period of the tension deviation. A tension-shaft speed controller controls a tension-control-shaft motor on the basis of the line speed reference and the adjustment manipulated variable during the adjustment of the control gain.

The roller-to-roller conveyance control apparatus includes an amplitude target setting unit that sets an amplitude target value of the tension deviation; an adjustment execution command generation unit that provides a command to adjust the control gain; an adjustment manipulated-variable output unit that outputs an adjustment manipulated variable; a manipulated-variable amplitude determination unit that increases the amplitude of the adjustment manipulated variable until the amplitude of the tension deviation becomes larger than the amplitude target value; and a control-gain calculation device that calculates the control gain from the amplitude and the vibration period of the tension deviation. A tension-shaft speed controller controls a tension-control-shaft motor on the basis of the line speed reference and the adjustment manipulated variable during the adjustment of the control gain.

A sheet feeding device includes a feeding guide of resin material constituting a sheet feeding path along which a sheet is fed; a feeding roller for feeding the sheet along the feeding path, the feeding roller being provided with a metal shaft; a sheet sensor configured to detect the sheet fed along the sheet feeding path; and a grounding member electrically grounding the shaft. The feeding guide has a guiding surface for guiding the sheet, and the guiding surface is provided with a hole portion for exposing the shaft to the sheet feeding path.

A sheet feeding device includes a feeding guide of resin material constituting a sheet feeding path along which a sheet is fed; a feeding roller for feeding the sheet along the feeding path, the feeding roller being provided with a metal shaft; a sheet sensor configured to detect the sheet fed along the sheet feeding path; and a grounding member electrically grounding the shaft. The feeding guide has a guiding surface for guiding the sheet, and the guiding surface is provided with a hole portion for exposing the shaft to the sheet feeding path.

A medium conveying apparatus includes a conveyance roller to convey a medium, a motor to drive the conveyance roller, a signal generator to output a pulse signal, a pulse width of which changes according to a rotation speed of the motor, and a processor to rotate the conveyance roller by controlling the motor, and detect a fluctuation of the pulse width caused by a load fluctuation when the conveyance roller conveys a medium to determine a thickness of the medium according to the pulse width.

A medium conveying apparatus includes a conveyance roller to convey a medium, a motor to drive the conveyance roller, a signal generator to output a pulse signal, a pulse width of which changes according to a rotation speed of the motor, and a processor to rotate the conveyance roller by controlling the motor, and detect a fluctuation of the pulse width caused by a load fluctuation when the conveyance roller conveys a medium to determine a thickness of the medium according to the pulse width.