Maintenance Basics | Secondary Transfer Unit (Part 7)

This issue shares the working principle of the Konica Minolta color printer's "Second Transfer Unit". The reference model is C364.
In the color printer, the second transfer unit uses a transfer roller and is the key component that actually transfers the image to the paper. If there is a problem with the second transfer unit, it will affect the overall image because it is a common part of the imaging process and all paper images must pass through the second transfer unit.

 

Drive

The second transfer roller is driven by the transfer motor to rotate the transfer belt. It presses on the transfer belt and rotates with it.

 

Transfer voltage

1. The high voltage unit provides the transfer voltage of the second transfer roller.
2. The transfer voltage will change due to the environment, usage time and other factors.
3. In order to maintain the best output voltage, the second transfer control is provided to pass a fixed current to the second transfer roller and detect the output voltage value at the same time. The appropriate second transfer voltage is determined based on the measured voltage value and other information such as "paper type used", "temperature and humidity", "color mode or black and white mode" and "single-sided/double-sided".

 

In addition to the above second transfer control, another control is provided during image stabilization. When the image is stabilized, a detection pattern image is generated on the transfer belt. In order to reduce the amount of toner adhering to the second transfer roller, a negative voltage is applied to the second transfer roller.

Cleaning

The second transfer roller does not have a cleaning mechanism like the first image transfer belt. So how to clean the toner adhering to it?

The machine will alternately apply a positive/negative charge to transfer the residual toner on the second transfer roller to the transfer belt, which will be cleaned by the cleaning mechanism of the transfer belt.

 

De-electrification and paper separation

After the second transfer roller completes the image transfer, the paper must be de-electrified and separated.

• The guide plate behind the second transfer roller is equipped with a de-electrification needle to eliminate the residual charge of the paper.
• A separation claw is installed in the center of the transfer belt to separate the paper.
• There is also a paper winding prevention guide above the transfer belt to prevent the paper from rolling into the back of the transfer belt and causing image failure.

IDC sensor protection

The IDC sensor is very important in the KM device, and many tests are completed by it. What if it gets dirty? It will cause detection abnormality, so the IDC sensor is equipped with a baffle mechanism to prevent it from being stained by toner. The baffle is controlled by an electromagnet to open or close.

Life

The life counter of the second transfer roller controls the life detection of the second transfer roller. If the count value of the transfer roller counter reaches the threshold, the machine will determine that the transfer roller has entered a new state.

When replacing new parts

• The second transfer roller is not equipped with a new part detection mechanism. Generally, it is replaced together with the transfer belt. The life clearance is the same as the transfer belt clearance. The new product release of the transfer belt is done in "Maintenance Mode-Counter-Life". The transfer roller life will be reset to zero.
• In order to prevent the substance contained in the new roller from sticking to the surface of the transfer belt and causing noise in the image, yellow toner will be applied to its surface when the second transfer roller is replaced. The process is to form a yellow toner image corresponding to two full circles of the transfer roller on the surface of the transfer belt, and then transfer the red image to the surface of the second transfer roller.

Conclusion

The Second Transfer Unit is a crucial component in the Konica Minolta color printer, directly impacting print quality and efficiency. Regular maintenance, proper handling, and understanding of its working principles—such as transfer voltage control, cleaning mechanisms, and life cycle management—are essential for ensuring optimal performance and longevity of your device. By following these guidelines, you can prevent common issues and maintain the high-quality output expected from your printer.