Inkjet Controls

rlj2104

I have a few of the HP 51604A cartridges used in the serial inkjet kit, and am trying to get them to fire. I don't have a huge amount of electronics experience...I'm pretty sure I've ruined a cartridge or two in the testing process. I've been looking at this document for an explanation of how things work:

http://www.parallax.com/dl/docs/prod/robo/InkjetKitDocs-v1.0.pdf

It says that the cartridge needs a series of pulses ranging from 4.5-6 microseconds with inactive periods of 500 microseconds between firing. I've been using an atmega to turn on the power to the cartridge for 6 microseconds and then off for 500 repeatedly...but am not seeing any results. I've also just been using 9v batteries (one...then two...then three) to try to get some reaction out of the thing, but still nothing. Any input on how I can make this thing give me some ink would be very greatly appreciated, as this cartridge seems to be a bit more tricky than I thought (i.e. I can't just plug something into two of its contacts and make it fire...or can I?).

Sorry if this is too general of a question, let me know if there is any more info that is needed. Thanks in advance.

Leon

A couple of people on the Homebrew PCB Yahoo forum have modified inkjet printers for applying resist directly to copper for making PCBs.

Leon

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rlj2104

Yeah, there are definitely a lot of interesting modifications to inkjet technology going around. I'm specifically trying to use the cartridge without a printer or any other pre-made controller. I want to be able to turn on and off the flow of ink from the cartridge, but I can't figure out what I need to give it to make it fire (the more minimal the better in terms of circuitry).

kwinn

Do you have a schematic of the printer or the actual printer so you can take a look at the signals going to the scope? Most inkjets use a resistor behind each nozzle to vaporize a small amount of ink. The pressure from that vapor bubble forces the ink in front of it out of the nozzle. The resistors could be tied to a common (ground/V+) and individually activated, or wired in a matrix similar to how 7 segment led displays are wired for multiplexing.

kwinn

After looking at your original post I notice you said "cartridge". Does the cartridge include the print head on this model?

rlj2104

Thanks for the fast responses!

http://www.hp.com/oeminkjet/products/51604A/specifications.html

That is the cartridge that I have (used in the serial inkjet kit), with the print head built in. It says in the specs that there are 12 nozzles, and considering that there are 13 contacts I'm assuming that the larger slightly separated one (visible in the picture) is the common ground. I still can't get any ink out of it. I think that I just need to know the right voltage/amperage/pulse speed, but so far my experimentation hasn't yielded anything.

kwinn

I think you are probably right about the contacts/nozzles. Do you have a scope you can use to look at the signal on one of the pads?

Zoot

The inkjet cartridge needs much higher voltage and current than what your micro will supply, unless you are using a driver and some kind of high-voltage source or a boost regulator. I believe that the cartridge needs somewhere on the order of 24v to fire -- the Parallax Inkjet board used an onboard boost regulator along with a sink-driver to drive the nozzles.

You could just hook up a bench 24v supply to the common term. of your nozzle driver and for the + side of the cartridge, tie the grounds together, and run the rest of your circuit from regular 5v supply (on board or external). That would let you test it out, anyway.

See page 33 of the Inkjet kit docs PDF for a schematic (boost reg. and sink driver). Unfortunately, Parallax no longer makes this amazingly well-designed board.

I have SX/B code over on my other machines that I can track down (based on Parallax's driver) if you want to see some timing code for nozzle firings combined w/data reads for printing character bitmaps and the like. It won't run on your micro, obviously, but will show a pretty decent outline of timing and the like.

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rlj2104

Kwinn, I don't have a scope, but the cartridge is pretty easy to see with the bare eye...but everything disappears under the plate that contains all the nozzles anyways, so I think I'm left to assume.

I read in the inkjetdoc that the cartridge needs around 24 volts, so I have been using what batteries I had to test it out...I connected 3 9v batteries in series (27v) and didn't get anything. I'm using a transistor (TIP31 AG) in a setup pretty similar to the one shown here (insert ink cartridge in place of solenoid):
http://www.arduino.cc/playground/uploads/Learning/solenoid_driver.pdf[noparse][[/noparse]url]
With various battery arrangements, I've given it 9, 18, 21, and 27 v, turning the signal on for 5 microseconds and off for 500 repeatedly, but with no response. I'm not very skilled with electronics, but that schematic helps a little bit...I think that code would help a lot as well if it isn't too much of a bother (thanks Zoot). It is really too bad that board isn't available anymore...I'm hoping that I can get some of the information from it to make something a bit less sophisticated on my own.

A bit about what I'm going for: I wrote a program that brings up a black and white jpeg on the screen, and sends a signal to the transistor whenever my mouse is over a black pixel, which then should send a shock to the cartridge to theoretically make it fire. The idea is that one can hold a cartridge next to a mouse, and move about randomly and have the image on the screen printed onto any surface. I think this would be really cool, and everything is in line (I tested it all with an LED)...but I just can't make this thing give me any ink! Hopefully that code will tell me something that I don't know about the necessary power supply and pulse speed...I didn't think that these cartridges would be so finicky...

Zoot

Here's the Parallax driver. A lot of the code is for managing comm. with micro host via TTL serial and writing/reading an I2C EEPROM which contains the character bitmaps as byte-based columns of pixels.... the part you will find of interest is the main print loop: bytes of pixels are fetched, doesn't matter from where, then broken up into the ALTERNATE inkjet nozzles (adjacent nozzles should not be fired simulataneously). See the main loop and the sub PUT_MAP.

Essentially it fires the EVEN nozzles, then ODD nozzles, but quickly enough it's like printing the whole column.

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Bean

rlj2104,
If you don't supply the correct voltage/amps/timing to those cartridges the nozzle heater will blow very easy. Then you get nothing.
Make sure you have extra cartridges to "play" with.

Bean.

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rlj2104

Thanks for that file Zoot, it gives me a bit more info on the timing and when to fire simultaneous nozzles. I still can't get even one though.

Bean...I've learned the hard way that these cartridges blow very easily. My experimentation has definitely destroyed a few with no real results, and at 16 bucks a pop I don't know how much longer I'm willing to attempt the guess and check method. I'm still hoping to get a bit more info on what this cartridge needs before I try it again. I'm pretty sure that it needs 24 volts with 5 microseconds on, 500 microseconds off, and I'm pretty sure that the larger contact that is slightly separated is the common ground, but I'm not sure about what amperage it will take, and in turn, what I should use for power...does anyone know if this info is in the book that comes with the kit?

Thanks again.

Zoot

The book has a full discussion of theory, implementation, various wiring/firing schemes, etc.

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rlj2104

So, I still can't get any ink out of the 51604 cartridge (or any at this matter) and am starting to feel like I'm hunting for the holy grail. I've got 22.5-24 volts with 5us on and 500 off for timing, but still nothing. I've looked everywhere for the "Inkjet Applications" book that came with the kit, but it is out of stock (out of print?) everywhere. I would really like to get this thing working. Does anyone have a copy of the "Inkjet Applications" book, and might be able to either: a. look at it for the most basic instructions/explanation of how to make the cartridge fire b. sell it on the cheap c. let me borrow it or have a look (NYC area). Any help would be really appreciated.

Thanks!

deadwhale

I think this MIGHT relate to what you are trying to do...

http://hackedgadgets.com/2007/01/17/injkjet-hacks/

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