The present invention relates to a package comprising a stack of flexible light-sensitive sheet material. Four corner pieces of a strong material embrace the short side edges of the stack, the pack is placed in a rigid box, and spring means are provided in the closed box for urging each corner piece towards the diagonally opposite corner piece on the stack of sheet material.

A packaging structure of planographic printing plates and an internal packaging material for the plates, which reliably protect the planographic printing plates from an external force, and which block the plates from light and keep the plates free from moisture; wherein the internal packaging material and an external packaging material are easily recycled. A stack of the planographic printing plates is internally packaged in the internal packaging material, whose light transmittance is a predetermined value or lower, and the stack is further packaged in the external packaging material. Light coming from the exterior of the closed external packaging material to the interior thereof becomes faint, and moreover, the planographic printing plates are prevented from accidental exposure due to a light-blocking property of the internal packaging material. In order to more reliably protect the planographic printing plates, the external packaging material has a predetermined strength, and further has a buffering property against changes in temperature and humidity.

A film package including sheets of imaging media or film sandwiched between upper and lower stiffeners and enclosed by an envelope. Adhesive strips secure the stiffeners together at overlapping tabs formed on opposite sides of the stiffeners. The stiffeners with the film sheets are removed from the envelope by opening one side of the envelope. The adhesive strips also have tear strips for allowing removal of the upper stiffener after the package has been placed in a drawer of a printer with the aid of offset tabs on the stiffeners which indicate and assure proper orientation. A notch in the corner of the lower stiffener allows a signal to be passed to indicate whether the upper stiffener has been removed. The lower stiffener is also apertured to receive a signal for indicating whether any film sheets remain on the stiffener while in the drawer of the printer.

A film package including sheets of imaging media or film sandwiched between upper and lower stiffeners and enclosed by an envelope. Adhesive strips secure the stiffeners together at overlapping tabs formed on opposite sides of the stiffeners. The stiffeners with the film sheets are removed from the envelope by opening one side of the envelope. The adhesive strips also have tear strips for allowing removal of the upper stiffener after the package has been placed in a drawer of a printer with the aid of offset tabs on the stiffeners which indicate and assure proper orientation. A notch in the corner of the lower stiffener allows a signal to be passed to indicate whether the upper stiffener has been removed. The lower stiffener is also apertured to receive a signal for indicating whether any film sheets remain on the stiffener while in the drawer of the printer.