Maintenance Basics | Development Department (Part 4)

This issue shares the working principle of the Konica Minolta color machine "Development Department". The reference model is C364.

Drive:

In KM color machine, the developer drive is divided into two parts. Black developer K is driven by the transmission motor. The drive is transmitted to the developer K only when the developer electromagnet is activated.
Color developers Y, M, C are driven by the developer motor.

 

Development bias:

The high voltage unit provides development bias (Vdc), which is applied to the development rollers of various color toners through the metal shaft of the development drive gear so that a sufficient amount of toner is adsorbed on the surface of the photosensitive drum.
In addition to the negative DC voltage, the machine also applies an AC voltage during development to make it easier for the toner to be pushed to the surface of the photosensitive drum. This AC voltage is only applied during development. At any other time, the machine only applies a negative DC voltage Vdc.

 

Automatic refining and developing system:

The toner bottle contains toner and carrier. When the toner is added to the developing unit, new carrier will be added. The excess and degraded carrier in the developing unit will be discharged, which can prevent the failure of the carrier in the developing unit and maintain stable image quality for a long time.

 

Toner replenishment:

1. Toner is supplied to toner screw 1 (hereinafter referred to as screw 1) through the toner replenishment port.
2. While the developer is agitated and charged, the toner is transferred to the rear of the machine by screw 1. During this process, the TCR sensor detects the ratio of toner to carrier, referred to as T/C ratio. If it is lower than the pre-run value, toner will be replenished.
3. The developer at the rear of the developing unit is again transferred to the toner supply screw 2 (hereinafter referred to as screw 2). The developer is transferred to the developing roller under the action of the magnetic pole of the developing roller.
4. The height of the magnetic brush is controlled by the developing scraper to keep the magnetic brush flat.
5. After development, the toner contained in the developer is pushed to the place where the laser is irradiated on the surface of the photosensitive drum, and the developer is sent back to screw 2 under the action of the magnetic pole. A part of the circulating developer is collected into the waste toner box through the toner collection port on the front side of screw 2.

 

Toner concentration control:

• A TCR sensor (non-contact magnetic type) is installed under each developer to detect the toner and carrier ratio, with a target ratio of 6.5+1.5%.
• The TCR sensor is integrated with the developer unit. When a new TCR sensor is needed, the entire developer unit must be replaced.

 

The TCR sensor is also used to detect whether the developer unit is installed in place and whether the developer unit is new. When TCR detects that the developer unit is new, the following operations are performed:

1. Execute TCR sensor automatic adjustment control.
2. Execute image stabilization control.
3. The developer unit life counter is reset to zero.
4. Execute life detection control.
5. The result of the new part detection is recorded in the machine.
6. The life counter can be used for developer units of various colors, and the counter value is recorded in the machine.

Lifespan:

The lifespan of the developer unit is determined by the print counter. When the count value reaches the threshold, the machine determines that the developer unit has entered a new state.

 

• When the print counter value reaches the service life threshold, the service life arrival screen will be displayed, and the print cycle can be enabled, but it exceeds the image quality guarantee range).
• When the print counter value reaches the service life end threshold, the service life end screen will be displayed. It is forbidden to initiate a print cycle).

 

Conclusion

The Konica Minolta C364 series uses a sophisticated development system that ensures high-quality color output by precisely controlling toner replenishment and toner concentration. The system integrates various sensors and motors to maintain image stability and prevent toner degradation over time. Regular maintenance and monitoring of the developer unit are essential to maintain optimal performance and extend the life of the machine.