Calibration and Cleaning Intervals

The HP Color LaserJet 4600 and 5500 series printers automatically calibrate and clean at various times to maintain the highest level of print quality. The user may also request the printer to calibrate via the printer's control panel.

While calibrating or cleaning, the printer will pause printing for the amount of time it takes to complete calibrating or cleaning. For most calibrations and cleanings, the printer will not interrupt a print job, but will wait for the job to complete.

These are the types of calibration executed by the HP Color LaserJet 4600 and 5500 either automatically or when the user requests a calibration at the control panel:

Density (DMAX)

Half tones (DHALF)

Color plane registration (CPR)

Drum phase (when calibration is requested from the control panel)

How does it work?

The printer performs several types of calibrations, including Maximum Density, Halftone Adjustment, and Color Plane Registration. For Maximum Density and Halftone Adjustment, the calibration is used to adjust the printer to a "nominal" state. This desired state is the result of characterizing many printers over life in different environmental conditions.

Halftone Adjustment calibration

The purpose of the Halftone Adjustment is to adjust the density between zero and 100%. As with Maximum Density calibration, patches are developed onto the electrostatic transport belt and read by the sensors. The data is then used to calculate the halftone mapping that will generate the desired nominal performance. The HP Color LaserJet4600 has the capability of mapping the 256 (8 bit) levels to over a thousand of possible internal printer halftone levels (halftone cell size times 8 bits). This is possible because of the internal laser modulation.

Color Plane Registration (CPR) calibration

CPR calibration sets several printer parameters: top of page, start of line, and scale in the scan direction. As with Maximum Density and Halftone Adjustment, all of the CPR calibrations come from writing patterns on the electrostatic transport belt and then using sensors to read the patterns. Variations in the timing of the patterns tell the printer how to compensate for top of page, start of line, and scale in the scan direction.

Once each of the calibrations is complete, the developed patches of toner are then cleaned off the carrier belt so the user never sees them. None of the internal calibration data is passed outside of the printer.

The HP Color LaserJet 4600 and 5500 calibrate at the following times, with these durations

After turning the printer on
75 seconds. Combined with other initialization activities, the printer will take a total of two minutes to come to a READY state.
65 seconds. Combined with other initialization activities, the printer will take a total of two minutes to come to a READY state.
DMAX and DHALF

After installing one or more color cartridges that have not previously been installed in the printer.
One minute and 15 seconds.
One minute and 50 seconds.
DMAX, DHALF, and CPR

After 50 pages have printed since installing a color cartridge, but at the end of the currently printing job.
75 seconds.
65 seconds.
DMAX and DHALF

After 1,000 pages have printed since the last calibration, but at the end of the currently printing job.
75 seconds.
65 seconds.
DMAX and DHALF

After eight hours since the last calibration, but not while the printer is in power save mode.

Typically, this calibration occurs on the first job or control panel interaction after an overnight idle period.
75 seconds.
65 seconds.
DMAX and DHALF

After requesting calibration from the control panel.
312 seconds (5.2 minutes)
Five minutes
DMAX, DHALF, CPR, and Drum Phase adjustment

The HP Color LaserJet 4600 and 5500 cleaning intervals

These are the types of cleaning automatically performed by the HP Color LaserJet 4600and 5500:

Electro-photographic process cleaning

Transfer belt cleaning

After the printer continuously printer for 51 pages with no idle period or spin down.
Five seconds (for toner charging roller)

21 seconds (for toner charging roller and ETB).

Note: Five seconds is the most common cleaning duration.

At intervals of 90 to 140 pages, but at the end of the currently printing job.
16 seconds (for the ETB).

When does color plane registration normally need to be executed?

Normally, color plane registration only needs to be executed after replacing a print cartridge. The HP Color LaserJet 4600 and 5500 will detect that a newly installed print cartridge or a cartridge that has not previously been in the printer. In each case, the HP Color LaserJet 4600 and 5500 will automatically execute color plane registration.

When the printer is turned on, it will not automatically execute color plane registration unless the printer detects a new or previously not seen print cartridge. Otherwise, the printer will only execute density and half-tone calibrations.

© 2005 Hewlett-Packard