Label Variations And The Label Sensor

Your T4204 is equipped with a transmissive sensor that detects the gap between labels while they are being printed. The trailing edge of the gap establishes the Top-of-Form position. This feature depends on the ability of the sensor to “see through” the label liner, index hole or notch in the media. In order to support this type of media, select the Transmissive option under the PRINTER CONTROL Media Sensor menu. The Transmission Media Sensor Assembly must be partitioned correctly. (See Sensor Assembly Horizontal Adjustment, below.)

A reflective sensor located on the lower portion of the same sensor assembly detects a black horizontal stripe on media with reflective label backing. The trailing edge of the black stripe establishes the Top-of-Form position. This feature depends on the ability of the sensor to detect the difference in the amount of light reflected off the back of the label material and the black stripe. Select the Reflective option under the PRINTER CONTROL Media Sensor menu in order to support this type of media. Additionally, the Reflector Sensor must be in the correct horizontal position.

Sensor Assembly Horizontal Adjustment

In order to accurately detect the gap, hole, notch, or narrow black stripe, the transmissive sensor assembly can be moved 1.4 inches along the width of the media by squeezing together the two blue locking tabs, located under the label guide, and sliding the sensor to the desired position. The actual location of the transmissive sensor is indicated by the sensor crystal visible at the front of the label guide when the printhead assembly is open.

Position the transmissive sensor directly under the hole or notch. If it extends the full width of the media, position it in the middle of the transmission liner gap.

The reflective sensor is located directly below R2, the resistor farthest to the right on the sensor PCBA. The resistor is visible when the printhead is open. The reflective sensor should be positioned as close as possible in the middle of the width of the label black stripe.

When you use either Transmissive or Reflective Media sensing, adhere to the media specifications described in Appendix A and ensure that the Page Length value set in the PRINTER CONTROL Main Menu of the Configuration Menu (or Page Length value sent via software command) matches the physical length of the label or tag stock installed in the printer. In addition, do the sensor calibration procedure described below whenever a different type of media sensing will be required (Transmissive or Reflective), when installing untried media, or when the printer is losing Top-of-Form position. Loss of Top- of-Form is usually followed by an error message on the LCD, such as “GAP NOT DETECTED Check Media” or “LOAD PAPER”.

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Printronix T4204 manual Label Variations And The Label Sensor, Sensor Assembly Horizontal Adjustment