摘要 |
A laser printer comprises a cartridge of a photosensitive unit, a printing mechanism (10) for effecting a printing operation by electrifying a photosensitive member of the photosensitive unit, applying a light beam to the electrified photosensitive member to form an electrostatic latent image thereon, developing the electrostatic latent image to create a visible image and then transferring the image to printing paper, and a nonvolatile memory (2) for storing data indicating the printing history of the photosensitive unit. The printing device further comprises a microprocessor (1) for updating the data stored in the nonvolatile memory (2) each time the printing operation is effected, checking whether the data stored in the nonvolatile memory (2) has reached a value corresponding to a service life of the photosensitive unit (42, 132), and generating a replacement requiring signal when it is detected that the data stored in the nonvolatile memory (2) has reached the value. |