| 摘要 |
A laser printer comprises a cartridge of a photosensitive unit, a printing mechanism 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 for storing data indicating the printing history of the photosensitive unit. The printing device further comprises a microprocessor for updating the data stored in the nonvolatile memory each time the printing operation is effected, checking whether the data stored in the nonvolatile memory has reached a value corresponding to a service life of the photosensitive unit, and generating a replacement requiring signal when it is detected that the data stored in the nonvolatile memory has reached the value.
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