Re: Removing the foam Was: ANOTHER New approach to Refilling

["Charles P Lamb" <CLamb@acm.org>]

----- Original Message -----
From: "Ralph O Brown" <robrown@evergreen-funds.com>
To: <epson-inkjet@leben.com>
Sent: Wednesday, January 19, 2000 11:31 AM
Subject: Removing the foam Was: ANOTHER New approach to Refilling


> I tried this sort of thing a while ago, removing part of the foam and
using an
> open top for filling on an Epson 1200 color cartridge. Apparently the foam
is
> there to hold the ink against gravity via surface tension and viscosity,
which I
> believe is related to why it fills with ink froth as the ink drains. I
tried
> cutting off about the top quarter of the foam and filling the cartridge to
its
> top, so there was a space with ink  but no foam at the top of the
cartridge.
> What happened was the ink simply dripped out until it reached the top of
the
> foam and then stopped. My conclusion was that the foam is essential for
this
> type of cartridge to work.

HP found a way around the sponge problem several years ago.  Their
cartridges contain a bladder glued to a flat spring such that the spring
tries to keep the bladder flat and empty.  The interior of the bladder vents
to the outside.  There is also a vent hole on the bottom of the cartridge
with a ball valve to only let air into the cartridge.  The bladder and
spring ensure a slightly less than ambient pressure in the cartridge.  The
bladder inflates and deflates in response to changes in ambient air pressure
in order to keep the ink inside the cartridge when not in use.  When used
the ink exiting the cartridge reduces the pressure inside the cartridge
causing the bladder to inflate slightly.  Eventually the bladder inflates
enough that the ball valve at the bottom of the cartridge opens letting a
little air into the cartridge.  This method controls the ink very well and
eliminates the sponge.  Its a lot more complicated but does allow more ink
in the cartridges.  I wonder why Epson doesn't adopt a similar design?
Perhaps they can't get around HP's patents.  It is more difficult to refill
than the sponge filled cartridges.  To refill it one must block the ink
nozzles (HP has the nozzles on the cartridge) and the bottom air vent.  Then
fill it with ink.  Then inflate the bladder and keep pressure in it.  Then
seal the ink fill hole.  Then let the bladder return to ambient pressure.
Then unseal the air vent hole and the nozzles.

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