A hat for the raspberry pi that allows a resin 3D printer's UV light projector to be controlled. Note that this is (in direct form) only suitable for the projector in the Mars 4 DLP. If you have other boards check out the repository for the Anycubic Photon Ultra, or get in touch for modifications needed.
The designs in this repository then allow you to project arbitrary 2560x1440 images with UV light on a surface. The native projected pixel size is 50μm, making PCB fabrication an interesting application. All you would need is a bit of glue code to convert the Gerber files to a rasterised image and then you could easily use the existing 3D printer frame to expose PCB boards. Since you have all the files and access to the code, you can easily tune it to whatever production needs you have.
The UV projector of the Elegoo Mars 4 DLP is developed and produced by Anhua (D63ZS50B), and seems to be this variety. Under the hood it uses the Texas Instruments DLP300s or DLP301s digital micromirror array.
[!NOTE]
While PCB fabrication is the most straightforward application for this board, this is actually developed as part of an effort towards an open hardware photolithography system. Check out the openMLA organisation for more info.If you have a projector using the DLPC1438 that uses the parallel video interface (rather than SPI) then you can check out the PCB design and implementation for the Anycubic Photon Ultra projector.
Running an SPI clock of ~125MHz it takes:
Arbitrary sections of the display can be updated for even shorter transfer times. Note the maximum framerate (below) and that due to technical reasons the smallest image block that can be sent (in terms of transfer size) is 128x2 pixels.
The image is stored in a buffer in the FPGA, so you can incrementally build or update an image, if that saves you time or makes your life easier.
The max achievable framerate seems to be about 10Hz (as there are some artefacts if you update faster). This is not a hard limit I suspect, and it may be possible to get closer to the display signal framerate of 60Hz.
The easiest and cheapest way to source the projector is to buy a Elegoo Mars 4 DLP. At the time of writing (2024-02-02) the resin printer can be purchased in the EU for 275 euro (discounted).
Alternatively, the projector can be purchased directly from Anhua; but there may be small differences in the heatsink, LED source and other items. Also expect to pay a premium due to shipping, broker cost etc.
The total costs for the project consists of 3 parts:
Expense Description | Cost |
---|---|
Elegoo Mars 4 DLP | 274 |
Electronics/PCB | 52.38 |
Enclosure/3D printed parts | - |
The PCB costs are further broken down in the BOM in the PCB directory
A basic 3D printable enclosure is available in the enclosure directory.
Disassembly of the printer is not difficult, but I suggest you take a look at the points below before starting.
Assembly of the board is pretty straightforward. For completeness, here are the steps you will need to take.