3-D Printer

Additive manufacturing, or 3D printing, is a process of laying down successive layers of material to produce a 3-D physical object. The object is specified by a 3D Computer Aided Design (CAD) model. 3D printer software transforms the virtual 3D model into a series of layers suitable for printing the object.

It is often used to quickly create detailed prototypes. With this technology, printing parts of a material can be done in a single process flow. 3D printers are becoming more affordable for medium and small scale businesses in which rapid prototyping is brought all the way into the office, no longer requiring manufacturing floor space.

Two common methods for 3D printing are digital exposure and laser sintering. The high level principles for incorporating DLP technology into a 3D printing solution can be applied to both methods, but digital exposure is represented in the system block diagram.

For the digital exposure technique, the 3D object is constructed by laying down successive thin horizontal cross-sections or layers of an ultraviolet (UV) curable liquid photopolymer resin. For each layer, the UV light image from the DLP® Digital Micromirror Device (DMD) creates a pattern which hardens the polymer resin where it is exposed to the light.

The cross-section pattern is produced by the individual mirrors that correspond to each pixel on the current layer. This pattern projects through an imaging lens onto the surface of the UV curable liquid photopolymer resin, curing or hardening it where the pixels are on. As depicted in the diagram, one resin is the build material and the second is material to support overhanging features and thin vertical walls during construction. The support material is later removed by heat or dissolved with a solvent or water.

These layers fuse automatically and the process repeats one layer at a time until the model is built. Cure rates are possible under 0.2 seconds per layer. Layer thickness typically ranges from 1um to 250um based upon the resin and wavelength of the UV light used. More detailed images require more discrete cross-sections to assume the continuous smooth surface effect of the resulting object.

The diagram shows a DLP chipset, which includes the DMD, and a DMD Controller chip, plus a DMD Analog Control chip (depending on the specific DLP chipset). DLP chipsets are available with different DMD sizes, pixel pitches, resolutions, and other specifications. DLP also offers devices targeted for use with UV light. The best choice for a DLP chipset may depend on the desired object feature size, patterning speed and necessary wavelengths to cure the resin.

The CAD model is produced by software running on a PC. The system control and signal processing is accomplished by the Embedded Processor (Such as TI OMAP®). Power is provided by TI Power devices. The details of the optical layout and components are not shown in the diagram. The diagram is intended to convey as simply as possible the overall functionality of a DLP-based 3D Printer application. An actual product will require additional optical components and optical design in order to achieve full functionality.