Patent ID: 7952703

Claim:
A film measuring method for measuring a physical amount of a microporous film to be formed on at least one of electrode plates of a positive electrode and a negative electrode of a secondary battery, the method comprising steps of: converting a color tone of a color image obtained by shooting the microporous film into gradation data of respective color components; and obtaining a physical amount of the microporous film by referring to pre-measured reference values of the physical amount of the microporous film corresponding to the gradation data of at least one of the color components obtained in the conversion step, using the gradation data of the at least one color component as lookup data, the reference values being stored as table data, wherein in the conversion step, the color image is converted into the gradation data of at least one color component selected in accordance with a material of the microporous film, and the table data represents the reference values of the physical amount of the microporous film stored corresponding to gradation levels of the at least one color component.