| 摘要 |
Photo film has pairs of perforations arranged at a regular pitch (L1+L2) along at least one edge thereof. Each of the pairs of perforations includes first and second perforations arranged at a small regular interval (L1) away from one another. A photo film advancing device has a rotatable sprocket wheel (41, 72, 80, 152, 252), a periphery of which has at least one pair of teeth, respectively including first and second teeth disposed away from one another nearly at the regular interval. The first tooth is engaged with the first perforation. The second tooth is engaged with the second perforation. A retaining member (44) causes the sprocket wheel to have a locked state, and disables the photo film from advancing when the second perforation is engaged with the second tooth. The retaining member causes the sprocket wheel to have an unlocked state and enables the sprocket wheel to rotate when a shutter operates. A plate spring (45) is associated with the sprocket wheel, and operates after the sprocket wheel is rotated as much as a small amount by advancement of the photo film while the sprocket wheel has the unlocked state. The plate spring rotates the sprocket wheel further as much as a predetermined amount in the same direction when the second tooth is moved away from the second perforation, so as to cause the first tooth to stand by for engaging with a succeeding pair of the pairs of perforations with the first tooth in contact with the photo film. The photo film is advanced in contact with the first tooth.
|
