Print quality problems. Form stacking, curling, melting problems. Top Of Form (TOF) and Pagination problems. Premature wear of print engine.

CAUSE:

Incompatible print media.

SOLUTION/PROCEDURE:

Use print media that complies with the following specifications.

GENERAL:

When evaluating label stock, remember that the LM1000 uses a thermal fusing/pressure process. The fusing temperature is 177∞ Centigrade. This is a fixed temperature for the LM1000 Models 1 & 3, and is the factory default for The LM1000 Models 5 & 6. The fuser temperature is adjustable on the Models 5 & 6. Ideally, it is best to lower the fuser temperature (Mode) for narrow forms (Mode = 4 or 5) to avoid "Fuser Failure". See Technical Bulletin 92-LM1000-145 for more information regarding fuser temperatures. The available fuser modes with there respective temperatures are as follows.

Fuser Temperatures in degrees Centigrade

0 - 130
1 - 138
2 - 146
3 - 153
4 - 161
5 - 169
6 - 177
7 - 184

Supported form widths for all LM1000 printers is 3.5"to 8.5"media with a 4"to 9.5 "carrier. These measurements are from outside edge to outside edge. The carrier must be wide enough to engage the paper out switch and the label must be wide enough to "sink enough heat away from the upper fuser roller". The maximum printable width is 8". Images cannot be forced outside of 8". The maximum printable width of the HPIII is 8.25".

Nonstandard form lengths for the LM1000 Model 1 & 3 range from .5 inch through 22 inches in .5 inch increments as well as the same standard page sizes that are supported on the HP Laserjet II (letter, legal, A4, etc.). It is best to design short labels and forms as a sheet of labels that will fit within a "letter"or 11 inch size page. The Models 1 & 3 will resync TOF every 11 inches or multiple thereof. Letter and 11 inch page sizes give the best registration and the least amount of creep and drift. If Letter size is used, allow for a top and bottom no print area of 1/5 inch. The 11 inch size does not have any non-printable areas.

Alternatively, Use a form length with repeats between the range specified above. This approach may not yield registration exactly, but it will be much easier to program the software for.

Nonstandard form lengths available for the Models 5 & 6 range from .5 inch through 33 inches in 1/8 inch increments. Metric sizes from 12 to 838 millimeters in 1 millimeter increments. The same standard pages sizes are also supported on the HP Laserjet III. The Model 5 & 6 have the capability to resync TOF at the bottom of any page size or can be set to resync every .5 inches. Registration is usually not an issue for the Model 5 or 6.

None of the LM1000 models can support page sizes by number of lines unless the selected size happens to fall upon a supported form increment. In other words, form lengths such as 3.66666 inches (22 lines) can not be supported.

Forms designed for the Models 1 and 3 are compatible with the Models 5 and 6. This is not necessarily true the other way around.

All LM1000 models require that the leading edge of the first form loaded into the printer, be separated from a perforation that splits directly between two drive holes. If the first form loaded has been separated on a perforation in any other position, TOF alignment will be erratic. It is best to avoid any off center perforation when designing new forms. The size A4 form has been known to exhibit this problem.

* Perforation Positions

LABEL STOCK:

Labels consist of three items: the label stock itself, an adhesive, and a backing paper.

When evaluating label stock, remember that the LM1000 engines uses a thermal fusing/pressure process. The fusing temperature is approximately 177∞C (392∞F). This means that labels that are used in a Dot Matrix printer, may not be suitable for the LM1000. Contact the label manufacturer for verification that a given label can withstand thermal fusing.

There are four kinds of label stock that are common today: plain paper, PVC (Polyvinyl Chloride), PET (Polyethylene Terephlatate), and Tyvek. PVC and PET are both vinyl plastic, we recommend plain paper or PET labels for this printer. We discourage the use of Tyvek because its adhesive damages the fuser roller and the label material melts. Note that PET labels may melt or burn when they touch a hot fuser and are not moving. If the print on the label seems smeared or smudged, the toner may not be getting fused into the label correctly and this tends to happen on PVC (vinyl) labels. The label stock is probably at fault if regular paper prints with no problems.

Two kinds of adhesives are common in labels: Acrylic Emulsion and Acrylic Solvent (We recommend Acrylic Emulsion labels). Acrylic Solvent labels are not recommended for use in thermal fusing because the adhesive may melt in the fuser, get squeezed out by the pressure roller, and come off on the fuser roller where it can't be removed by the fuser wiper. The adhesive then burns onto the fuser roller and shortens its life. Note also that labels peeling off their backing in the printer (before the fuser) should be replaced by labels that have a stronger adhesive.

The two types of backing (base) paper are Kraft and semi-glassine. We recommend Kraft paper backing because it tends to handle the fuser heat better. Its one drawback is that it sometimes stretches as it goes through the fuser. This may result in the print shifting on labels being printed later in the print run. Semi-glassine backing paper should not be used because it tends to get stiff after it has passed through the fuser. Extremely thick backing sometimes causes problems in the toner transfer process. This is evident by weak or broken characters that appear only on labels and not on paper. If this problem occurs labels with a thinner backing should be tried.

Labels cut with the surrounding material (but not the backing) removed are called "Matrix-off"labels. "Matrix-on"labels are recommended because the matrix-off labels tend to allow adhesives to melt onto the fuser roller. Matrix-off labels also can slip in the fuser due to the difference in height between the label and the backing. Slippage is especially evident when the height difference is large due to an extremely thick label and a thin backing. Slipping usually doesn't result in paper jams, but may result in blurred print. the backing also tends to be slippery and the fuser will sometimes not pull labels through the printer correctly. When label stock slips in the fuser, the stock moves slower and the surface of the OPC drags across the label causing blurred print and possibly loss of TOF.

* Matrix On: Full-Coverage Label Stock

* Matrix Off: Label Stock having space between each label

PAPER STOCK:

Paper stock can affect the fixability of the toner and the overall print quality. Fixability is a measure of how well the toner adheres to the paper. Paper is produced with two dissimilar sides which are the "felt"side and the "wire"side. The felt side is recommended, but it is difficult to tell which side is which due to manufacturing techniques. The toner is a specially formulated powder with certain electrostatic and thermoplastic characteristics. It must melt with the heat provided by the fuser, then it must adhere to the stock with the pressure provided by the pressure roller. The electrostatic characteristics of the toner generate a charge from the rubbing together of toner particles due to agitation in the developer. This charge enables it to be properly attracted to the OPC drum and to adhere to the stock being printed.

The LM1000 Print Engine is designed to work with most types of paper. However, some variables in different papers may have a significant affect on print quality. The quality of the paper is an important factor in the proper transfer of toner onto the paper. These quality factors/specifications include:

• To improve stacking performance use paper with a "double perf". Double perf has twice as long cut out segments with narrow attaching segments. Avoid micro or laser perf paper.
• Bond vs. xerographic/laser paper type - Typical "bond"paper performs adequately, but is not optimum. "Xerographic"paper is similar, but usually has more tightly controlled moisture content and smoothness. This should result in better image quality, fixability, and less curl after fusing.
• Conductivity/surface electrical resistance - 108-1012 ohms at 20∞C and 65% humidity. The target resistance is 109 ohms. This is a measure of the paper's ability to conduct electricity. The paper must be a relatively good insulator in order to get the developed image to transfer from the OPC drum to the paper.
• Moisture content - 4-6% by weight - The moisture content of the paper can be effected by the humidity in the air it is stored in. It is recommended that paper be stored in moisture proof package at 15 to 32∞C (59 to 90∞F) and at a humidity of 30 to 70%. It is a good idea to let a new box of paper sit next to the printer for a couple of days before use. This allows it to acclimate to the temperature and humidity it will be used at.
• Paper that is extremely dry will have a tendency to build a great deal of static electricity as it is being printed. This then discharges and may cause image quality and stacking problems. Extremely wet paper will tend to cause problems in the transfer process and may result in a weak image.
• Curl - This usually happens with paper that has a high moisture content. The side of the paper towards the fuser/heat roller dries more than the side with the pressure roller. This results in the paper curling toward the heat roller side. "Xerographic"paper tends to be less susceptible to this phenomenon than "bond"paper.
• Smoothness - 100-200 Sheffield or 30± Bekk - Smoother paper allows more consistent contact with the OPC and results in better toner transfer. Paper that is extremely smooth, shiny, coated, or is highly textured should not be used.
• Caliper/thickness - 3.2 - 4.5 mils - Paper that is very thin, recycled, or light weight is not recommended as it doesn't stack well after it has been fused. The fuser tends to iron or press the fold out of the paper.
• Source - Where and from whom the paper is bought can effect the print quality. For instance, Japanese paper tends to be about 10% better in fixability than comparable American paper. Contact Output Customer Technical Service for recommended forms sources.
• Basis Weight - 15-24 lb. (56-90 g/m) - the basis weight is the weight of one ream (500 sheets) of the parent sheet for the type of stock being weighed. The parent sheet size will vary according to the type of stock.
• Fusing Compatibility - The stock being fused must not scorch, melt, or release hazardous materials when heated to 200o C (392o F) for 0.3 seconds.
• Sizing material - the sizing used in the manufacture of the paper may effect the ability of the toner to be fused into the paper.

• Papers with oil, dust, or adhesive material on them.
• Paper having extremely strong or weak between page perforations.
• Letterheads using low temperature dyes or thermography. These materials may offset onto the fuser roller and cause damage. Any pre-printed stock should use inks compatible with 200∞C (392∞F) for 0.3 seconds.
• Damaged (creased, ripped, torn, or highly curled) or wrinkled paper.
• Paper that is cut at more than 14∞ off of square on the long side. This tends to skew in the printer.
• Paper that has been previously passed through the laser printer.