Laserjet print quality on large grey shaded areas

L

leewm

Hi,

Recently I had to print a document which had a fine grey shaded
background on my HP laserjet 3030.

Dark words and lines came out crisp. However, I noticed that there is
some kind of faint horizontal banding which repeats every
approximately 20 mmin the shaded background.

The fine grey shaded background is made up of evenly spaced, tiny
dots.

The toner cartridge was changed but the "problem" persisted.

Is this a hardware limitation of the HP laserjet or is there some
hardware problem (eg: a spoilt 6mm diameter roller)?

Is it time to send it in for repair?

thx
weemeng
 
T

Tony

leewm said:
Hi,

Recently I had to print a document which had a fine grey shaded
background on my HP laserjet 3030.

Dark words and lines came out crisp. However, I noticed that there is
some kind of faint horizontal banding which repeats every
approximately 20 mmin the shaded background.

The fine grey shaded background is made up of evenly spaced, tiny
dots.

The toner cartridge was changed but the "problem" persisted.

Is this a hardware limitation of the HP laserjet or is there some
hardware problem (eg: a spoilt 6mm diameter roller)?

Is it time to send it in for repair?

thx
weemeng
Click to expand...

This printer does not contain a roller with a 20mm circumference. The smallest
is about 30mm. I assume you are measuring from the beginning of one defect to
the beginning of the next, vertically (A4 or letter portrait).
Most laser printers can suffer shading in large gray areas and it is usually
the toner cartridge. Are you using original HP cartridges or remanufactured
cartridges?
Tony
MS MVP Printing/Imaging
 
A

Arthur Entlich

I can't say for sure what the cause is of the described defect, but I
have noticed that some image files with grayscale gradients develop a
type of interference phenomenon similar to what you've reported.

If you can, try using a different dithering or dot pattern in your
printer driver, or even try changing the printer resolution in use, and
see if that has any effect. I don't know which program you used to
create the document or to print the document, but some allow you to
alter the formation of the dots, dot placement or density, and this may
help you to get around the problem.

Art
 
L

leewm

Hi Tony,
This printer does not contain a roller with a 20mm circumference. The smallest
is about 30mm. I assume you are measuring from the beginning of one defect to
the beginning of the next, vertically (A4 or letter portrait).
Most laser printers can suffer shading in large gray areas and it is usually
the toner cartridge. Are you using original HP cartridges or remanufactured
cartridges?
Click to expand...

I used MS Word, grey filled, rectangular box. I tried increasing the
shading from 25% to 80%.

As it became darker, I could see that there are small fine horizontal
lines that appeared as well.
The horizontal shading banding was most obvious when the shading was
25%.
At 40% shading, I could see numerous horizontal fine lines clearly.
They were not so obvious as it became darker.

There's so many banding but staring at the 80% shaded rectangle, it
seem to repeat every 90mm or so.
After 90mm, there's a 20mm lighter coloured banding, followed by some
random horizontal banding. Then there is the 20mm lighter banding
again.

I'm using original HP toners.

thx
weemeng
 
T

Tony

leewm said:
Hi Tony,


I used MS Word, grey filled, rectangular box. I tried increasing the
shading from 25% to 80%.

As it became darker, I could see that there are small fine horizontal
lines that appeared as well.
The horizontal shading banding was most obvious when the shading was
25%.
At 40% shading, I could see numerous horizontal fine lines clearly.
They were not so obvious as it became darker.

There's so many banding but staring at the 80% shaded rectangle, it
seem to repeat every 90mm or so.
After 90mm, there's a 20mm lighter coloured banding, followed by some
random horizontal banding. Then there is the 20mm lighter banding
again.

I'm using original HP toners.

thx
weemeng
Click to expand...

Sorry I really don't know what this is. There isn't a roller with a 90mm
circumference. The largest is about 76mm (Drum in the cartridge).
The rollers in the printer have circumferences of
31mm
38mm
76mm
All in the cartridge

41mm
57mm
In the fuser

46mm Transfer roller

55mm Paper feed roller (this will never cause shading issues).

I guess it could be the transfer roller but your description indicates a less
than regular repetition so it is hard to diagnose.
this printer uses the Laserjet 1010, 1015 series engine and in my opinion these
engines do not produce great prints that have large shaded areas.

1. Press MENU/ENTER.
2. Use the < or > button to select Reports and then press MENU/ENTER.
3. Use the < or > button to select either Config report , Demo Page , or Menu
Structure
and then press MENU/ENTER. The product exits the Menu settings and prints the
report.

I think the demo page may have a shaded block on it, what does that look like?
Tony
MS MVP Printing/Imaging
 
W

Warren Block

Tony said:
Sorry I really don't know what this is. There isn't a roller with a 90mm
circumference. The largest is about 76mm (Drum in the cartridge).
Click to expand...

Sounds like it could be halftone artifacts. The clue would be if the
lines are different at different gray levels. I looked for a web page
that would explain this easily, but didn't find anything in a quick
search except patents on methods of avoiding artifacts.

For the OP: try lots of different gray levels. You may find a few that
are much better than the others; it depends on resolution and halftone
screen.
 
T

Tony

Warren Block said:
Sounds like it could be halftone artifacts. The clue would be if the
lines are different at different gray levels. I looked for a web page
that would explain this easily, but didn't find anything in a quick
search except patents on methods of avoiding artifacts.

For the OP: try lots of different gray levels. You may find a few that
are much better than the others; it depends on resolution and halftone
screen.
Click to expand...

You could well be right. As I previously mentioned I am not entirely happy with
this engines ability to produce large gray blocks, what I don't know is whether
someone produces a specialised toner cartridge that does a better job (for
grayscale photographs for instance). I have a customer who does excatly this
from a LJ1020 for proofing grayscale photographs and he is not entirely happy
with the results and to date we have been unable to resolve the issue.
Tony
 
A

Arthur Entlich

That would also be my opinion based upon the nature of the description.
Each laser printer uses a different screening method and indeed some
create interference patters and other anomalies.

Art
 
A

Arthur Entlich

Creation of grayscale is a complex function with a laser printer. It is
dependent upon internal firmware as well as driver and sometimes even
the document source. The dpi of the engine should improve grayscale
definition the higher the dpi density is, in theory, but I have found
that there can be conflicts between the document data and the firmware
and engine design. Unfortunately, the specs on "paper" don't always
tell you what you'll get ON the paper.

Art
 
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