FNO Warning. Read only if you have a technical interest.
This half off thread, and half on thread. It concerns Canon iP4200, etc., the chipped devils, and CIS.
I am seriously considering a CIS that uses the maker's own spongeless cartridge in the printer. The maker has solid claims and some good reports. A spongeless in the CIS assembly is very desirable, as a periodic flushing is probably avoided. The CIS assembly offers a unique opportunity for its designer, in that he can more directly control the ink pressure sent to the print head.
The action of a sponge in a cartridge is a little on the black magic side. The presence of two different textures of sponge in the Canon OEM cartridges makes the mystery even deeper. Canon doesn't do this for laughs. They may have learned from a great deal of emperical trials. When I look at the combination of the sponges, the air vent above them, the necessity of perfect sealing of the tank side, and the ink path at the bottom of the tank into the bottom of the sponge, I believe I understand the goal, but I could not predict that it would be accomplished.
Maybe the sponged cartridge function is somewhat like a felt tip marker. The marker is willing to give up ink when the tip is touching something that will absorb some ink, but it won't continue to flow and puddle once the touched spot is wet enough. (The felt tip marker normally is touched to paper, but will act the same way when touching something that can only absorb so much ink before being too wet to absorb more.) When needed, more ink is fed to the marker tip from the wick-like material in the tube which is the marker's ink reservois. There is a definite air vent in the marker's reservois area. If one were to tap an ink tank into the marker's ink reservois tube, maybe part way up the tube, and have it be a sealed tank with no top air vent, would the ink move from this tank into the the reservois tube's wick material just as needed, and not more? Since the tank will drop to a negative pressure when ink is removed, only wicking action, due to low enough surface tension, will move ink from the tank and into the wick. When the pressure in the tank is low enough, some air must be allowed into the tank. This air must come through the wick of the reservois and back into the ink tank, and as it does, the tank pressure will rise enough to allow a bit more ink to move into the wick.
Now, figure out how to make a felt tip marker with a felt-like tip, which uses ink with a viscosity near water, has a tank of liquid ink connecting directly to the felt tip, and isn't prone to letting too much ink go through the felt tip and mess up your shirt pocket. I would never, ever, say it can't be done, but I believe it would be a big challenge to the ingenuity of the engineer who would tackle the problem.
If making a spongeless cartridge is for simplicity, that could be a business reason to try.
If making a spongeless cartridge is for economy, that may not be a good enough reason. Very small costs.
If making a spongeless cartridge is to eliminate periodic flushing, that would be good.
If making a spongeless cartridge just moves a problem on down to the print head, is that good?
I understand that periodic cartridge flushing is to remove some collected gunk from the sponge.
Without a sponge, does the same gunk collect in the wick material at the print head entrance?
Wouldn't gunk in the print head entrance wick, if it occurs, be a problem?
If there were no sponge, could we imagine that no gunk would form?
Are my hopes for the CIS with no sponges, thus no periodic flushing, just false hopes?
Haven't I typed enough now?
