UV bandings

[AFFCup]

Hi all,

I've used the ColorSpan 5440 (or DJH 45500 from HP), ink used is UV ink.

The software is Onyx Production House 7.3

Normally, when I print the job with the image is OK, but for the solid color or background, alot of UV banding appeared on the print out.

Do you have any experience about the UV bandings? Please help

Thanks

 

[Ford Prefect]

What kind of banding do you see? Is it parallel with the motion of the Printheads?

 

[AFFCup]

Hi Ford Prefect,

The bandings look like the ink density different between pass, because the UV ink will be dried when the head carriage move to the left to right side, and the second pass from the right to the left, so it make the density different between directions and we call the UV bandings.

We also calibrated the media feed already. All head status are good.
I've hear that this is the limitation if we use the UV ink technology.

Thanks for your help.

 

[beermonster]

its a by product of uv's - usually more in production mode as it puts less ink down as it's going faster - hence the banding - there's some fancy name for it - i forget

you can try single strike, unidirection and even up to 12 pass - but thats almost into top quality mode - it sgoes slower, hence puts more ink down hence less banding

basically it's a trade off between quality and speed

some heads give less - variable dot size heads may give less perhaps compared to fixed picolitre heads - again its a trade off

long story sideways - top quality gets rid of most banding

ohhh just remembered - it's called "striping"

i saw no/VERY little banding in production mode with the acuity, some with arizona, lots with apollo , some with gerber

 

[guru]

The term is Chromatic banding. This is a problem with all UV machines.

Its caused by two different problems one is the overlapping of colours (registration) this is a result of the piezo technology. It is impossible to keep the head alignment in line with over lapping of each pass. You can compensate for example if you compensate for the correction on green then you will through out the compensation for red as cyan over lapping yellow has to be dealt with differently to yellow overlapping magenta. This is handing to know to deal with specific artwork but really most of the time middle of the fence is the best.


The second issue is caused by the UV lamps. As the lamp cure one pass then cure the second pass the lamp covers a large amount of area so the previous pass gets a second dose and creates a band.

I find the best solution is unidirectional advised by beermonster at high pass rate.

 

[VladCanada]

Different countries - different names. Somewhere in Europe I heard
''Stitching effect"

 

[Eyal Gragir]

UV Gloss Banding

UV Gloss Banding

Uni directional is the solution. multi passing will eliminate gloss so beware.
i would also recommend doing a linearisation ink limiting and color profile using the same mode of printing to avoid color problems.

 

[Ford Prefect]

AFFCup,
Sorry I did not reply sooner. I have been rather busy. Looks like the others have already said what I would suggest, using Unidirectional printing. This will eliminate this problem in most cases.

 

[Eyal Gragir]

if you want to keep the paste with bidirectional printing try tunings the lamps to equal power. lamp power differences will create gloss banding even in high quality modes.

 

[printheadz]

You could also try turning your trailing lamp on only, if your printer supports that. I've found that one lamp at a high power is our best looking print.

 

[ScotJ]

i saw no/VERY little banding in production mode with the acuity, some with arizona, lots with apollo , some with gerber

The acuity and arizona are the exact same machine. Fuji just relabels it as there own.

 

[JohnPNE]

Take it to uni-directional. That may help.

Color Span printers are very low end and do not have the algorithms to properly interlace in bidirectional mode.

If the bands are really small, like 1pt it is head drop out. If they are the same size as the each pass, it is banding do the limitations of the ink. Since the inks do not whet out as much as solvent, the refract the light in opposing directions. Same concept for the grass on a baseball field.

John
http://printnewengland.com

 

[JohnPNE]

Buy a Vutek QS or GS series or a Fuji Spyder.

Most low end presses (under 200K) are crap.

 

[beermonster]

scotJ - i know

it was interesting to see same machine by 2 vendors give different results......run by different rips though