Xerox DocuColor 12 question

I have a quick question regarding the DocuColor 12. The specs show 50
ppm b&w, 12 color. My question is if there's spots of color, does the
entire page slow down to 12 ppm, or does it only slow down for the
parts of the page that has color? For example, if I only have color on
a logo at the top of the page, does it only slow down for the logo then
speed back up for the remainder of the document? If not, do any of
laser printers do that?
Wes

"wes" <> wrote:
>I have a quick question regarding the DocuColor 12. The specs show 50
>ppm b&w, 12 color. My question is if there's spots of color, does the
>entire page slow down to 12 ppm, or does it only slow down for the
>parts of the page that has color? For example, if I only have color on
>a logo at the top of the page, does it only slow down for the logo then
>speed back up for the remainder of the document? If not, do any of
>laser printers do that?
>Wes

Laser printers only operate at one speed for any particular print format.
So if there is colour in the print it will operate at the colour speed for the
entire page. They do not accelerate or decelerate during printing.
Tony

In article < .com>,
"wes" <> wrote:

> I have a quick question regarding the DocuColor 12. The specs show 50
> ppm b&w, 12 color. My question is if there's spots of color, does the
> entire page slow down to 12 ppm, or does it only slow down for the
> parts of the page that has color?

A laser printer is a page printer; the entire page must be composed
before the paper goes in.

The entire page slows down.

There should probably be some distinction made here.

There are several things that go into print output speed.

1) Time taken for first copy to be color separated and rasterized within
the computer and transferred to the printer memory

2) Time taken for the laser(s) to create the image on the drum(s) (when
several colors are used)

3) Time taken for the drum image to be transferred to either paper or
transfer belt

4) Time taken for paper to be fused and ejected from printer.


The times provided by most laser printer companies are usually optimal,
may or may not include first print out times or any computer processing
time, and are averages based upon the content of the image.

Spot color images may take less time than a full page color graphic
image, for instance, especially if it only requires one toner color
besides black to be accomplished. If there is a lot of blending and
shading requiring all 4 toner colors, that will slow the process down.

You will notice in most printer reviews that a suite of document types
using different software are fed to each printer and an average time is
usually presented. This is because each printer will take differing
time for each process. It isn't like there are two "speeds" one black
and white, one full color or any use of color at all. The speed will be
determined by the demands made of the printer.

Art

Elmo P. Shagnasty wrote:

> In article < .com>,
> "wes" <> wrote:
>
>
>>I have a quick question regarding the DocuColor 12. The specs show 50
>>ppm b&w, 12 color. My question is if there's spots of color, does the
>>entire page slow down to 12 ppm, or does it only slow down for the
>>parts of the page that has color?
>
>
> A laser printer is a page printer; the entire page must be composed
> before the paper goes in.
>
> The entire page slows down.
>

In message <mI1_g.160503$1T2.39706@pd7urf2no>, Arthur Entlich
<e-> writes
>The times provided by most laser printer companies are usually optimal,
>may or may not include first print out times or any computer processing
>time, and are averages based upon the content of the image.

They tend to be engine speeds and so for the DC12, once its up and
running it will churn pages out a 50 per minute (assuming they are
duplicate copies) in mono or 12 in color (presumably 12.5 4x12.5=50) It
might have an option to use 2 or 3 of its four colours, which should
make it proportionately quicker.

So if the page has a bit of C,M,Y & K on it, even if its a very simple
page the machine would slow down to the 12 ppm, but a simple page would
have a shorter time between you pressing print and the first page coming
out the machine.

A thing I've noticed with my Bizhub is every now and then it takes a
breather in the middle of a print run, I think the display says its
doing image stabilisation or some such. Maybe about 20 seconds?


--
Timothy

In article <mI1_g.160503$1T2.39706@pd7urf2no>,
Arthur Entlich <e-> wrote:

> It isn't like there are two "speeds" one black
> and white, one full color or any use of color at all. The speed will be
> determined by the demands made of the printer.

Dude, you are entirely wrong.

I worked on the DocuColor 12 engineering team. You are so far off base.
You are talking just to hear yourself talk.

The DC12 engine has two speeds at which it passes paper: one if there's
color on the page, and one if there's black only on the page.

For you to stand there and try to convince the world otherwise is to
shout your ignorance from the rooftops.

Thanks for the correction, Elmo. Apparently, I've been misinformed. Is
this two step engine speed true for all color laser printers, or is it
the nature of the Xerox products, or this particular printer?

See, I can shout from the same rooftops that I've been misinformed about
something and learned something new. ;-) No big "ting".

Art

Elmo P. Shagnasty wrote:

> In article <mI1_g.160503$1T2.39706@pd7urf2no>,
> Arthur Entlich <e-> wrote:
>
>
>>It isn't like there are two "speeds" one black
>>and white, one full color or any use of color at all. The speed will be
>>determined by the demands made of the printer.
>
>
> Dude, you are entirely wrong.
>
> I worked on the DocuColor 12 engineering team. You are so far off base.
> You are talking just to hear yourself talk.
>
> The DC12 engine has two speeds at which it passes paper: one if there's
> color on the page, and one if there's black only on the page.
>
> For you to stand there and try to convince the world otherwise is to
> shout your ignorance from the rooftops.
>

In article <JJi_g.166004$5R2.31207@pd7urf3no>,
Arthur Entlich <e-> wrote:

> Is
> this two step engine speed true for all color laser printers, or is it
> the nature of the Xerox products, or this particular printer?

The DC12 has one imaging drum; it must be imaged four times to make a
complete image.

It's imaged for one plate, which gets transferred to the intermediate
belt; it then gets imaged for the next plate, which is transferred to
the belt; and so on, until all four separations are on the intermediate
belt. It then pulls paper and transfers the fully composed image from
the belt to the paper.

Doing this, the DC12 runs at 12ppm.

If you're using only one of the inks (any one), it will go at 50ppm.

Other printers use four separate imaging drums, which obviously
dramatically increases the speed of color printing--but on the other
hand, even a black-only page prints at the exact same speed as a full
color page.

OK, that explains a lot to me. I wasn't familiar with the design of the
DocuColor 12. The insides of most consumer color lasers I have looked
at in recent years do use 4 separate toner cartridges with integrated
drums and one transfer belt.

Art

Elmo P. Shagnasty wrote:

> In article <JJi_g.166004$5R2.31207@pd7urf3no>,
> Arthur Entlich <e-> wrote:
>
>
>>Is
>>this two step engine speed true for all color laser printers, or is it
>>the nature of the Xerox products, or this particular printer?
>
>
> The DC12 has one imaging drum; it must be imaged four times to make a
> complete image.
>
> It's imaged for one plate, which gets transferred to the intermediate
> belt; it then gets imaged for the next plate, which is transferred to
> the belt; and so on, until all four separations are on the intermediate
> belt. It then pulls paper and transfers the fully composed image from
> the belt to the paper.
>
> Doing this, the DC12 runs at 12ppm.
>
> If you're using only one of the inks (any one), it will go at 50ppm.
>
> Other printers use four separate imaging drums, which obviously
> dramatically increases the speed of color printing--but on the other
> hand, even a black-only page prints at the exact same speed as a full
> color page.
>

Colour laser printers come in two flavours. The industry terms are
four-pass, and single-pass. Oops, guess which we have here in the
DocuColor 12?

I'm not saying any of you are absolutely wrong. In fact, I think
you've all got a piece of the puzzle. But I think Elmo got the
biggest piece in this particular case.

Effective throughput of a printer is dependant on quite a number of
variables. Document complexity, duplex/simplex, input bandwidth, and
yes, engine speed can all affect throughput, depending on the severity
of the condition. Resolution can cause a change in absolute engine
speed, but this usually occurs only between print jobs (600 dpi and
1200 dpi image mode on a mono Lexmark Optra, for example). Also, if
you try to feed your fast, 60 ppm printer a 1200 dpi, image-laden
data stream across a 9600 bps serial line, of course it will choke,
big time! This is one of many reasons that can cause a printer
stall, so-called because it results in the engine stopping, even
momentarily. In our business, the fastest we can drive workgroup
lasers across our national network during peak hours, with all kinds
of other online traffic, is about 35-45 pages per minute. Putting a
bigger printer on the end of that pipe accomplishes absoluting
nothing, unless we pump up the bandwidth. However, local performance
might still be outstanding.

But that's not what is happening here.

Early colour lasers (and now 'value-level' colour lasers) are
four-pass devices. Available technology at the time allowed only one
colour to be imaged at a time, required four full passes of the media
(either the transfer drum/belt, or the paper) to image all four
colours (CMYK). These devices differentiated only between colour and
monochrome print jobs, not by pages. Either the job was a single-pass
monochrome, or it was four-pass colour. There is no 2-pass, or 3-pass
mode, no in-between speed. If any colour was called for on any page,
the printer's effective throughput for the entire print job would be
reduced by a factor of 4 because of the 4-pass operation. There's
your speed difference. The DocuColor 12 is an earlier, four-pass
printer. The first 4-pass I encountered, was the Xerox 4700 II (Huge,
300 dpi floorstanding model rated at 7.5 ppm colour, 30 ppm
monochrome). A more recent desktop example is the Lexmark C710 -
loud and clunky as the cartridges rotated to the next colour between
passes. A current example of a value four-pass is the Xerox Phaser
6120.

Current technology has rendered the four-pass almost obsolete, except
for value devices. Most colour lasers are now single-pass devices,
which allow full imaging of all 4 colours (CMYK) in a single pass of
the media. These devices usually have matching colour and monochrome
speeds, and they're a lot quieter. Some models may be slightly
faster at monochrome, based on printer design, because the paper path
may be shorter due to bypassing colour imaging stations. Current
example of such a single-pass device: Xerox Phaser 6350.

Here's a recent review of 3 'value' colour lasers, two single-pass
devices, and a four-pass device... interesting.

http://www.crn.com/sections/hp/hp.jh...leId=175701284

Regardless, the absolute print engine speed in both one-pass and
four-pass devices should be constant, all other variables being
equal, and non-detrimental to performance.