Re: Refilling cartridges - how do you cover the hole?

Gary Tait <classicsat@xxxxxxxxx> wrote:
>Tony <TonytheTigurrrrr@xxxxxxx> wrote in
>news:part1of1.1.G8uYEChzyoMAwA@xxxxx:
>
>> "ZR" <ZR@xxxxxxx> wrote:
>>>>>>Another question is why the cartridge will leak if the hole is not
>>>>>>air tight, considering there are breathing holes on the cartridge?
>>>>>
>>>>>
>>>>> That's easy to answer. The cartridge is a balance between surface
>>>>> tention and gravity. For example take a straw, put it in a drink.
>>>>> Cover the straw tip with your finger. Pull it out. The liquid has
>>>>> enough surface tention to not drip. But start removing your finger
>>>>> slowly and then it'll drip drip drip depending on the size of the
>>>>> gap.
>>>>>
>>>>> That's why you don't want a huge hole... it'll leak. A small hole
>>>>> is needed above the sponge to replace the displaced ink but make it
>>>>> too large and it'll leak too quickly.
>>>>>
>>>>> Very simple but effective design.
>>>>>
>>>> Strictly speaking surface tension has nothing to do with the finger
>>>> on a straw example. It is a balance between the weight of the
>>>> liquid and air pressure. The same principle keeps water in the
>>>> chicken waterer, the dog water machine, the humming bird feeder,
>>>> etc. The effect is easiest to observe with an old fashioned
>>>> mercury tube barometer.
>>>>
>>>> As gravity pulls the liquid down, a vacuum develops at the top of
>>>> the tube and air pressure on the liquid pool at the bottom pushes
>>>> the liquid back up the tube. To see anything significant with water
>>>> you need a very long tube, but with mercury you can watch as the top
>>>> of the mercury column moves up and down around 30 inches above the
>>>> pool as the air pressure changes.
>>>>
>>>> In and ink cartridge, the first compartment of an ink cartridge acts
>>>> as the sealed tube and second compartment (sponge compartment) acts
>>>> as the pool. The only way for the ink level to move down in the
>>>> first compartment is for air to enter from the sponge compartment to
>>>> increase the bubble of air at the top. If you could watch it you
>>>> would see a bubble of air develop at the bottom hole and rise to the
>>>> top of the first compartment, just like what happens with a
>>>> hummingbird feeder.
>>>>
>>>> Although surface tension is necessary, it isn't really a factor in
>>>> an ink cartridge because the surface tension of water is great
>>>> enough that water will hang in columns that are many feet in length.
>>>> Anyone who has use the old type of water pump that operates with
>>>> the piston at the top of the well could tell you that.
>>>
>>>Sounds like the fundamental design of inkjet print is inherently
>>>unstable and unreliable. Fortunately I got a laser as backup.
>>>
>>>Thanks!
>>
>> With respect that is a little unfair on inkjets. It is important to
>> remember that when they were first designed there was no alternative,
>
>How so? For general purpose personal, even commercial, printing, people
>used either daisywheel or dot matrix impact. Later on Dot matrix impact
>got color, and at least at 1985, simple (black or single color) dot-
>matrix ink printers were around, and least to regular users, in the
>later 80s/earlier 90s.

I was referring to quality rather than text printng and I may not have made
that clear.
My recollection is that colour dot matrix printers only printed the colours on
the ribbon, photographs weren't an option.
So far as I, know short of buying a professional printer for megabucks, the
average person could not buy a photo printer until the inkjet came of age
albeit they were not very good at that job in the early days. That was the
point I was trying to make as well as that especially in the early days of
inkjets the technology was very challenging.

>The tech has been around, at least in the lab, since the late 1970s.
>
>> it was the only technology that allowed ordinary people to print at a
>> reasonable cost. Things have changed, lasers are so much cheaper now
>> but even the best colour lasers are not as good as photo quality
>> inkjets at producing high quality prints unless you pay thousands of
>> dollars. Epson seem to have the edge in photo quality.
>> Having said that, inkjets are actually extremely high tech, the simple
>> appearance of these printers belies decades of research. And what you
>> get for the money now that the bulk of the research has been amortised
>> is quite remarkable. Sure there are problems with inkjet technology
>> but the problems are not out of line with their complexity in my
>> opinion. Tony
>
>I am goindg to disagree with you, to a point. The tech is pretty well
>the same, a far as the core bits, it has been improved, as well as the
>ink and papers.
The real advances in recent years relate to speed of throughput and at the same
time far greater resolution and longevity, that results from superior head and
ink design, especially the heads.
I don't think we really disagree, if you want to spend the money you can buy
superb fast inkjets with high reliability like the HP professional printers
with separate heads or top of the line Epsons that produce superb photographs,
but we are talking 3-4 times the price of a modest inkjets. Having said that
the high end printers are much cheaper than they were.
Cost of running them is an entirely different topic!
Tony

.

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