Techncial Note 4 - Print Station
The print head is a precisely machined slice of ceramic, on the bottom edge of which is a row of tiny heating elements (resistors), 300 to the inch. A thin glaze coating protects the heating elements. Under normal operating conditions the head is capable of printing many thousands of images.
Damage to the head, meaning a permanent failure of one or more heating elements (“pixels”), can be caused by solid particles on the card surface, even though the color ribbon affords some degree of protection. The automatic card cleaning system in the P640 takes care of most issues, but the operator should keep the inside of the printer clean by occasional vacuuming. Also bear in mind that it is not a good idea to run the printer with the cover open (by cheating the interlock switch), except for test purposes.
Missing, or “blown” heating elements show up as a white unprinted line. This calls for a replacement print head. Less seriously, a faint line may be due to debris or contamination, which can sometimes be corrected by cleaning the print head. (A faint line may also indicate a heating element on the verge of failure, or a
small piece of torn ribbon stuck under the head.)
Examples of printhead problems
The white line in the center of the black stripe suggests a number of blown pixels. The wide black stripe means that a large number of pixels are fully on (hot) all the time. Either of these problems may call for a replacement printhead (but the black stripe may be caused instead by image handling issues between printer driver and the application that created the card layout).
Caution • Do not touch the bottom edge of the print head. Grease or other contaminants from the hands can attract particles that may in time dameage the head.
Electric Shock Caution • Make sure power is disconnected before working on the print head. Also note that the head will likely be destroyed if power is reapplied while you are in porcess of reconnecting the cable, or if the plug is not seated properly.
Cleaning the print head
Do this only if print quality has deteriorated and all other corrective actions have failed.
1.Open the main cover (this will raise the print head).
2.Remove the color ribbon.
3.Wipe the bottom edge of the print head a few times using a
4.Dry off with the lint free cloth, taking care not to touch the active edge.
Important • The angle of the print head relative to the surface of the card is set by this
3
Not Used
Access for
head
2 angle
Yaw adjust (technician
only)1
44 | P640i Card Printer User Guide |