HP blue light

Archived from groups: comp.periphs.printers (More info?)

"geo" <luckyone@iol.it> wrote in message
news ve7d.39597$35.1832652@news4.tin.it...
> During printhead allignment there is a blue light.
> Does anybody know how it works?

The alignment page prints a series of black and yellow blocks, as well as
pattern of black and yellow lines. There is a blue LED and an associated
sensor that measures the offset between the black and yellow blocks in the X
and Y dimensions and then corrects appropriately. Later versions (starting
with the DeskJet 990?) also examine the reflectance from the paper to detect
paper types automatically.

Regards,
Bob Headrick, not speaking for my employer HP

Archived from groups: comp.periphs.printers (More info?)

In article <Pve7d.39597$35.1832652@news4.tin.it>, luckyone@iol.it
says...
> During printhead allignment there is a blue light.
> Does anybody know how it works?

It's simply a blue LED. There is a sensor next to it to read the
reflection. I think the main reason blue is used is because it's 'cool
looking.' At work, we have a DesignJet 650C, which uses green.

By monitoring the refelection while scanning across the special
patterns, the printer can determine the correct cartridge offsets.
Yellow is used for the color cartridge alignment because it looks black
under blue light.

--
If there is a no_junk in my address, please REMOVE it before replying!
All junk mail senders will be prosecuted to the fullest extent of the
law!!
http://home.att.net/~andyross

Archived from groups: comp.periphs.printers (More info?)

1-2 weeks ago the color cart had a bad clog.I ran a cleaning cicle and then
an allignment .On the printed A4 i could clearly see that the cart was still
cloged but the allign procedure was (for HP) perfect.,with the green arrows
on the left(that i could barely distinguish).
So i decided to clean manually the cart ,with success.I ran a new head
allignment but this time i tried to fool him.I printed on a A4 Dark Grey
(almost black) pre-printed paper.The results....Again perfect (for HP).I
doubt that the sensor could "see" the printed patterns.The printer just put
a green arrow again and the allignment was finished.
I don't believe that this procedure works.
Does anybody know how to test it?

Thanks for the replies !!!
"Bob Headrick" <bobh@proaxis.com> wrote in message
news:10lrjt98honfsa9@corp.supernews.com...
>
> "geo" <luckyone@iol.it> wrote in message
> news ve7d.39597$35.1832652@news4.tin.it...
> > During printhead allignment there is a blue light.
> > Does anybody know how it works?
>
> The alignment page prints a series of black and yellow blocks, as well as
> pattern of black and yellow lines. There is a blue LED and an associated
> sensor that measures the offset between the black and yellow blocks in the
X
> and Y dimensions and then corrects appropriately. Later versions
(starting
> with the DeskJet 990?) also examine the reflectance from the paper to
detect
> paper types automatically.
>
> Regards,
> Bob Headrick, not speaking for my employer HP
>
>

Archived from groups: comp.periphs.printers (More info?)

"geo" <luckyone@iol.it> wrote in message
news:qol7d.26295$75.1196725@news3.tin.it...
> So i decided to clean manually the cart ,with success.I ran a new head
> allignment but this time i tried to fool him.I printed on a A4 Dark Grey
> (almost black) pre-printed paper.The results....Again perfect (for HP).I
> doubt that the sensor could "see" the printed patterns.The printer just put
> a green arrow again and the allignment was finished.
> I don't believe that this procedure works.
> Does anybody know how to test it?

The alignment does work. If the sensor could not see the pattern there would
not be a checkmark on the last line. You may notice the sensor first checks
the blank paper to get a nominal reading before it starts the alignment. It is
rather immune to paper types, although it may fail on yellow paper or
transparency.

If you want to test the alignment try making a black box in Photoshop (about 1"
on a side) with sides 1 pixel wide. Now replace a bit of the side and top with
a color strip. An alternate pattern would be a thin cross of black (or color)
with extensions of color (or black). Print in plain paper normal mode.

Regards,
Bob Headrick, not speaking for my employer HP

Archived from groups: comp.periphs.printers (More info?)

On Fri, 1 Oct 2004 14:41:10 -0700, "Bob Headrick" <bobh@proaxis.com>
wrote:

>
>"geo" <luckyone@iol.it> wrote in message
>news ve7d.39597$35.1832652@news4.tin.it...
>> During printhead allignment there is a blue light.
>> Does anybody know how it works?
>
>The alignment page prints a series of black and yellow blocks, as well as
>pattern of black and yellow lines. There is a blue LED and an associated
>sensor that measures the offset between the black and yellow blocks in the X
>and Y dimensions and then corrects appropriately. Later versions (starting
>with the DeskJet 990?) also examine the reflectance from the paper to detect
>paper types automatically.
>
And, the light is used to align the paper. From the 990Cxi onwards
(another good workhorse printer from HP - but I won't be buyi9ng any
more because I know that, as soon as the next MS OS comes out, I won't
be able to run the printer and HP won't produce a driver for at least
a year).

--

Hecate - The Real One
Hecate@newsguy.com
veni, vidi, reliqui

Archived from groups: comp.periphs.printers (More info?)

The head allignment is still "perfect" even with damaged printhead
http://www.webalice.it/geocha/cart_78.htm
"Bob Headrick" <bobh@proaxis.com> wrote in message
news:10ls7jbraulb08@corp.supernews.com...
>
> "geo" <luckyone@iol.it> wrote in message
> news:qol7d.26295$75.1196725@news3.tin.it...
> > So i decided to clean manually the cart ,with success.I ran a new head
> > allignment but this time i tried to fool him.I printed on a A4 Dark Grey
> > (almost black) pre-printed paper.The results....Again perfect (for HP).I
> > doubt that the sensor could "see" the printed patterns.The printer just
put
> > a green arrow again and the allignment was finished.
> > I don't believe that this procedure works.
> > Does anybody know how to test it?
>
> The alignment does work. If the sensor could not see the pattern there
would
> not be a checkmark on the last line. You may notice the sensor first
checks
> the blank paper to get a nominal reading before it starts the alignment.
It is
> rather immune to paper types, although it may fail on yellow paper or
> transparency.
>
> If you want to test the alignment try making a black box in Photoshop
(about 1"
> on a side) with sides 1 pixel wide. Now replace a bit of the side and top
with
> a color strip. An alternate pattern would be a thin cross of black (or
color)
> with extensions of color (or black). Print in plain paper normal mode.
>
> Regards,
> Bob Headrick, not speaking for my employer HP
>
>

Archived from groups: comp.periphs.printers (More info?)

I don't own an HP printer, but I have watched the alignment process on
them on occasion.

From what I can see, the alignment requires a certain amount of yellow
and black printing. If the "damaged" cartridge you speak of was able to
provide enough black and yellow information printed onto the paper, the
alignment process should work. I suspect if very little or no yellow
and or black ink was printing, then the alignment process would not have
enough printed information to make the necessary adjustments, but it
certainly is possible the alignment process doesn't require fully
functional printheads to do so. The heads may well be aligned and still
be partially clogged or "damaged", if that be the case.

Anyway, the image is either aligned or it isn't... unaligned heads would
show up with off-registered color.

Art

geo wrote:

> The head allignment is still "perfect" even with damaged printhead
> http://www.webalice.it/geocha/cart_78.htm
> "Bob Headrick" <bobh@proaxis.com> wrote in message
> news:10ls7jbraulb08@corp.supernews.com...
>
>>"geo" <luckyone@iol.it> wrote in message
>>news:qol7d.26295$75.1196725@news3.tin.it...
>>
>>>So i decided to clean manually the cart ,with success.I ran a new head
>>>allignment but this time i tried to fool him.I printed on a A4 Dark Grey
>>>(almost black) pre-printed paper.The results....Again perfect (for HP).I
>>>doubt that the sensor could "see" the printed patterns.The printer just
>
> put
>
>>>a green arrow again and the allignment was finished.
>>> I don't believe that this procedure works.
>>>Does anybody know how to test it?
>>
>>The alignment does work. If the sensor could not see the pattern there
>
> would
>
>>not be a checkmark on the last line. You may notice the sensor first
>
> checks
>
>>the blank paper to get a nominal reading before it starts the alignment.
>
> It is
>
>>rather immune to paper types, although it may fail on yellow paper or
>>transparency.
>>
>>If you want to test the alignment try making a black box in Photoshop
>
> (about 1"
>
>>on a side) with sides 1 pixel wide. Now replace a bit of the side and top
>
> with
>
>>a color strip. An alternate pattern would be a thin cross of black (or
>
> color)
>
>>with extensions of color (or black). Print in plain paper normal mode.
>>
>>Regards,
>>Bob Headrick, not speaking for my employer HP
>>
>>
>
>
>

Archived from groups: comp.periphs.printers (More info?)

Andrew Rossmann <andysnewsreply@no_junk.comcast.net> writes:

> In article <Pve7d.39597$35.1832652@news4.tin.it>, luckyone@iol.it
> says...
> > During printhead allignment there is a blue light.
> > Does anybody know how it works?
>
> It's simply a blue LED. There is a sensor next to it to read the
> reflection. I think the main reason blue is used is because it's 'cool
> looking.' At work, we have a DesignJet 650C, which uses green.
>
> By monitoring the refelection while scanning across the special
> patterns, the printer can determine the correct cartridge offsets.
> Yellow is used for the color cartridge alignment because it looks black
> under blue light.

Also the LED is used to determine the paper type (assuming you have auto paper
type selected in the driver).

--
Michael Meissner
email: mrmnews@the-meissners.org
http://www.the-meissners.org

Archived from groups: comp.periphs.printers (More info?)

>By monitoring the refelection while scanning across the special
>> patterns, the printer can determine the correct cartridge offsets.

I wonder why more printers don't use this, for example they could create a
servo system that could be used to print better photos on color paper or could
be used to clean the head repeatedly until there are no clogs. Remember the 3
head cassette decks?? It could work like that.