An air flow controller includes: a box-shaped body cover that is disposed above and/or below a film running surface to be adjacent to an upstream side of an entrance of a tenter oven in a film running direction and/or a downstream side of an exit of the tenter oven in the film running direction, the box-shaped body cover extending in the film running direction and having a surface facing the film running surface and being open. The box-shaped body cover includes at least one partition structural body in the box-shaped body cover, the partition structural body extending in a width direction of the film and separating inside of the box-shaped body cover into a plurality of chambers, and each of at least two of the chambers is provided with an air discharge mechanism configured to discharge air in a corresponding chamber.

The separator production method in accordance with an embodiment of the present invention includes a coated article taking up step of taking up a separator original sheet by winding the separator original sheet on an outer peripheral surface of a core while oscillating the core in the rotation axis direction; a coated article winding off step of winding off the separator original sheet, which has been taken up in the coated article taking up step, from the core; and a transferring step of transferring the separator original sheet, which has been wound off in the coated article winding off step, such that a state of being distorted in a wavelike manner in the transverse direction is maintained.

A method of making an optical film includes providing a film, substantially uniaxially orienting the film, and heat setting the oriented film. The film includes a polymeric material capable of developing birefringence.

A method of making an optical film includes providing a film, substantially uniaxially orienting the film, and heat setting the oriented film. The film includes a polymeric material capable of developing birefringence.

A film-stretching apparatus in accordance with an embodiment of the present invention includes a stretching furnace which is divided into a plurality of air amount control zones. In a case where the number of the plurality of air amount control zones is seven, a total amount of air to be discharged from, out of the plurality of air amount control zones, three air amount control zones which are located on an entrance side of the stretching furnace is controlled so as to be larger than a total amount of air to be discharged from, out of the plurality of air amount control zones, three air amount control zones which are located on an exit side of the stretching furnace.

A film-stretching apparatus in accordance with an aspect of the present invention includes a stretching furnace which has (i) an entrance through which a material film is transferred into the stretching furnace and (ii) an exit through which the material film having been stretched is transferred out of the stretching furnace, an airflow in the entrance being controlled so as to be directed toward an outside of the stretching furnace.

A film-stretching apparatus in accordance with an embodiment of the present invention includes a stretching furnace having (i) an entrance through which a material film is transferred into the stretching furnace and (ii) an exit through which the material film having been stretched is transferred out of the stretching furnace. An airflow in the entrance is controlled so as to be directed toward an inside of the stretching furnace. A gas in the stretching furnace is controlled so as to be discharged outside the stretching furnace.

A film-stretching apparatus in accordance with an aspect of the present invention includes a stretching furnace which has (i) an entrance through which a material film is transferred into the stretching furnace and (ii) an exit through which the material film having been stretched is transferred out of the stretching furnace, an airflow in the entrance being controlled so as to be directed toward an outside of the stretching furnace.

A film-stretching apparatus in accordance with an embodiment of the present invention includes a stretching furnace which is divided into a plurality of air amount control zones. In a case where the number of the plurality of air amount control zones is seven, a total amount of air to be discharged from, out of the plurality of air amount control zones, three air amount control zones which are located on an entrance side of the stretching furnace is controlled so as to be larger than a total amount of air to be discharged from, out of the plurality of air amount control zones, three air amount control zones which are located on an exit side of the stretching furnace.

A film-stretching apparatus in accordance with an embodiment of the present invention includes a stretching furnace having (i) an entrance through which a material film is transferred into the stretching furnace and (ii) an exit through which the material film having been stretched is transferred out of the stretching furnace. An airflow in the entrance is controlled so as to be directed toward an inside of the stretching furnace. A gas in the stretching furnace is controlled so as to be discharged outside the stretching furnace.