3D printer

The invention relates to a printer. A 3D printer comprises a cylinder body, a curing starting switch, a spraying device, a DLP (Digital Light Processing) projector, a piston type worktable and a computer, wherein a storing box of which the upper end is opened is formed between the upper surface of the piston type worktable and the inner surface of the cylinder body; the spraying device comprises a spraying head provided with a spraying port, scrappers, and a driving mechanism which is controlled by a computer and can be used for driving the spraying head to move synchronous with the scrapers; the spraying head and the scrapers are positioned above the piston type worktable; the DLP projector can be used for directly projecting into the storing box from the top of the projecting box; the DLP projector is provided with a light outlet, a light outlet cover, a cover closing spring which can drive the light outlet cover to close the light outlet, and an electromagnet which can drive the light outlet cover to open; the curing starting switch can be triggered when the spraying head moves to an end point of a travel so as to enable the electromagnet to be electrified to generate magnetism. The 3D printer has the advantage that the ultraviolet rays can be directly projected on a resin layer, so that the problem of low utilization rate of the ultraviolet rays of an existing 3D printer can be solved.