Senior Design Project - Printer Hydration System
mcenbold
Posts: 6
Hey all,
I am working on a design project and need some help with the electronics since everyone is a mechanical engineer. For the project we are taking a current hydration system in a high speed production printer, and replacing and improving components to reduce system cost and increase functionality. The system logic is currently run by an Allen Bradley MicroLogic 4000 PLC. We want to replace the PLC with something less expensive. We don't need the fluidity that the PLC provides and are considering the BASIC Stamp 2. Could we make this work for our project?
I am working on a design project and need some help with the electronics since everyone is a mechanical engineer. For the project we are taking a current hydration system in a high speed production printer, and replacing and improving components to reduce system cost and increase functionality. The system logic is currently run by an Allen Bradley MicroLogic 4000 PLC. We want to replace the PLC with something less expensive. We don't need the fluidity that the PLC provides and are considering the BASIC Stamp 2. Could we make this work for our project?
Comments
2. What do you need to control? What kind of outputs?
3. What kind of feedback does the system provide? What kind of inputs?
4. How fast does the control system need to respond to those inputs?
-Phil
One of Ricoh’s newest improvements is a hydration system for use in their line of high speed production inkjet printers. The company found that after extensive use during the day, the printheads would sit overnight and develop clogs. To remedy this issue Ricoh developed a hydration system that constantly keeps small pads inside the caps wet. The printheads rest on these pads when not in use, allowing them to keep from drying out and clogging. Every day the water in the pads and lines is vacuumed out, along with the glycol left behind by the ink, and the pads are then refilled with water. This is an important process because if the pads dry out, then the glycol in the pads will absorb water from the printheads when they rest on the pads. This causes the ink to dry out and the printheads to clog. The hydration system was a relatively quick fix that has proven to be effective. Ricoh believes however that the system is too expensive and has tasked our team with finding a way to reduce cost. The project is very open ended with possible improvements ranging from finding cheaper materials to design changes in the system.
The current system has an Allen Bradley MircoLogix 1400 PLC, an Allen Bradley MicroLogix 1400 Relay Output Expansion Unit, and and Allen Bradley Panelview C300. The PLC was initially used because there was a lot of potential for the system programming to change.
The Stamp would have to control two large vacuum pumps, 9 solenoids, and receive input from a distance sensor (to determine when the printheads are away from the caps allowing for the cycle to run). The system has three parts to it. When the system starts it vacuums out the lines connected to the caps to remove all water/ink in the lines. It then pumps water back through the lines into the caps to hydrate them, and again purges the lines to clean out excess. This process has to happen once a day to keep the printheads from drying out. The whole process must run in less than 2 minutes, and the time the cycle can run is completely reliant on whether the printheads are in use or not so it does not occur at the same time every day.
This is somewhat difficult to explain without diagrams. Let me know what I can clarify and other questions that need to be answered in order to give you a better idea of whats going on here. Thanks Phil and Mike!
-Phil
With the times involved, the Stamp should be able to keep track of the times involved even though it doesn't have a built-in clock. You should be able to use a PAUSE statement as an accurate time tick for the 24 hour timeout as well as the shorter times for the various parts of the cycle.
The solenoids could probably be driven by a couple of Darlington arrays if the current levels are low enough (500mA). The pumps may need a relay which would be driven by the Darlington array. There are all sorts of other options once you describe the voltage and currents involved.
Take a look at the EFX-TEK Prop-2 controller which uses a BS2 and includes 2 x 8 Darlington arrays that can handle 24V solenoids or relays. You don't have to use all the Darlington outputs and could attach your sensor(s) to some of the I/O pins.
The Prop-2 controller looks pretty good from what I can actually understand about it. I have what might be a dumb question, but this is almost like another language for me... what is the difference between a prop controller and any other type of controller?
Other Stamp boards might be optimized for other uses (in terms of built-in functionality).