Density Check Factors - HP LaserJet II Serie Manual De Instrucciones

HP 33440/HP 33449 COMBINED SERVICE MANUAL
Density Check
The perception of densi~ (blackness) is
customer's print quality with respect to
subjective. For a service representative to evaluate the
densi@, both the service person and the customer must
judge the suspect problem from the same point of view. The following variables must be clarified
or defined before a true evaluation mn OCCUE
Table 7-49. Density Check Factors
1. Densi@ Adjustment
)id.
1. Environment
>onditions.
1. Perceived Density
rersusOptid Density.
;. EP-S Cartridge.
I. Resolution
~nhancement.
HP 33449 only.)
Paper is one of the largest variables that may affect the perception of a
densi~ problem. Ml types of paper react differently to the laser imaging
process. The surface texture, paper color (degree of whiteness), paper
type, and moisture content dl contribute to density perception.
When addressing suspected densi~ problems, both the service
representative and the customer must evaluate the problem from
the same reference point. It is important, therefore, that dl density
evaluations be made using the same type, if not the same lot of paper.
It is recommended that U evaluations be made using Xerox 4024 or
Canon NP copier bond paper.
The printer's Densi~ Adjustment Did changes the developer DC
bias and, therefore, the amount of toner attracted to the drum. For
evaluating suspect density problems, ensure that dl print samples are
printed with the Densi@ Did set to the "5" (mid-range) position, (See
Chapter 4, Section 4-9.)
Mthough difficult to duplicate, factors such as printer location (with
respect to sunlight humidity, and temperature) should not be ruled out
regarding their contribution to print quality.
A difference in perceived density versus optid densi~ is often evident
when someone is asked to judge bold print versus itilc print. In most
roses, bold print is judged to be more dense just because the stoke
weight is heavier and not because the toner is "blacker."
To etiminati the perceived densi~ phenomenon, dl densi~ comparisons
should be made using the same print patterns. It is recommended that
dl density evaluations be based on the Service Mode Self Test Printout.
A new EP-S Cartridge wi~ appear to print sfightiy darker than the last
pages of a my used (approximately 4,000 pages) mrtridge. This is due
to the individud dot sizes being slightiy larger on a well used caltridge.
This condition is the result of a progressive "blooming" effect caused
by the continued working of the laser on the drum's photoconductive
matirid.
The Resolution Enhancement feature of the HP 33449 and the density
adjustment affect each other. See Chapter 3, Section 3-4, for proper
adjustment procedures.
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