Canon LBP6000, HP LaserJet Pro P1102, M1132 and M1212 Transfer Roller RM1-4023.

Transfer Roller

These printers look different but are all based on the same print engine, so the transfer roller does the same job.

The transfer roller is close to the heart of what a laser printer does so if there are image quality problems it could be the cause. They do decay with age, can be damaged by mishandling but most likely the roller and its surround are just dirty.

Changing the roller will often improve print quality but it rarely addresses a fundamental fault where the printer just doesn't work. A brief explanation of how the print process works may help.


Transfer Roller Purpose

A laser printer makes the page image on an electrically charged OPC drum. OPC is "Organic Photo Conductor" - a plastic material which is non conductive in the dark but conductive in the light. The drum is located in the cartridge and is given a charge of several hundred volts by a pre-charge roller located in the top of the cartridge. The drum then rotates past a slit which the laser scans across. Exposure by laser light discharges the drum and the result is a "latent image" in static electricity.

Laser Printer Function

The drum continues rotating past a developer roller, also part of the cartridge. The developer carries a layer of toner powder close to the drum. Differences in the static charge on the drum and the triboelectric charge carried by the toner "develop" the image

  • little or no toner sticks to the white areas of the latent image
  • sufficient toner to give a solid black image sticks to the dark areas

The drum continues rotating until it is over the page to be printed, which is travelling under it propelled by the registration rollers.

Under the page at this point is the transfer roller. It is conductive plastic and carries a charge that attracts the toner off the drum, holding it firmly on the page.

The page travels on to the fuser, where the toner is heated and pressed into the paper making a very robust image.

The OPC drum rotates further past a scraper blade which removes waste toner, leaving the drum surface ready to go past the precharge roller and start again.

Paper Path

Transfer Roller Issues

If paper fails to pass the registration station the leading edge sensor won't move at the right time and the printer will stop with paper stuck in position between the registration rollers.

However a minor mis-timing could result in the page continuing to move but not being positioned correctly. Toner will then miss the paper and get onto the transfer roller. A build up will alter the voltage on the surface of the transfer roller.

Transfer rollers are black foam. Rollers with toner contamination look matt black, the foam texture of the roller is not discernible. Transfer roller contamination is not readily discerning looking at the print; the rear of newly printed pages will have erratic streaks of black, but those could also come from the fuser - and if the transfer roller is dirty the fuser will innevitably pick up some contamination.

Transfer rollers attract paper dust as well as toner. Low cost mechanically cut paper often has some paper dust in the stack, and this will build up on and near the roller. Transfer rollers with excessive dust contamination look rather grey.

The usual issue with a dirty transfer roller is that the page lacks contrast and any solid black areas may have dropouts that fade to grey. Toner that should have transferred goes to waste.

Transfer Roller

Transfer Roller Cleaning

The Canon LBP6000 service manual says: Basically, do not touch it with your hands or clean it. When cleaning is absolutely necessary, clean with a dry lint-free paper. Take care not to touch the roller and let solvents or oils be removed.

The quickest way to deal with transfer roller contamination is to use a toner-rated vacuum cleaner. Rotate the roller by it's cog, not by fingering the foam. (Do not use an ordinary vacuum cleaner, the dust will penetrate the pores in the bag and blow around. Toner dust may form an explosive mixture as well - a dirty printer is better than an exploding vacuum cleaner! )

Cleaning the roller and its recess without a vacuum cleaner is annoying. It is possible to take the transfer roller out and remove most of the dust with a clean paintbrush. Using a can of spray-duster will help- but do it outside where the dust can mix with city grime and diesel particulates. Alternatively use damp tissue to remove the dust but obviously things have to dry thoroughly.

If the transfer roller becomes contaminated again the cartridge is suspect. Refurbished cartridges sometimes leak a bit. Typically the drum seals intended to prevent waste toner leaking out get slightly buckled either during use or during the refurb process and toner dribbles through the gap. The corners of the cartridge are particularly vulnerable.

If the transfer roller has been in use for some time it will be denatured and worn by contact with the leading edge of the paper and need replacement.

Extracts from the Canon Instructions


Extracts from the HP Instructions

The roller seems to appear under several part codes:

HP Documentation says the roller is RM1-4023-000CN (AKA RM1-4234).

Canon distributors say RM1-4023 as well which is the roller used in the HP P1005, P1006, P1009, P1505, M1120 and M1522.

Although HP use a different grade of toner in the Laserjet Pro M1132 and M1210 this doesn't seem to mean any difference in transfer roller.