Charge/Development Bias Control and Vtref Compensation

Charge/Development bias control and Vtref Compensation is done using the following procedure. Its operating time varies depending on the machine’s line speed.

Adjusting the ID sensor Vsg

This step adjusts ID sensor’s LED’s light intensity so that Vsg, which is the ID sensor output when monitoring the bare surface of the ITB, becomes within 4.0±0.5V. When Vsg does not reach the target value three times, the machine issues SC370 (ID sensor Calibration Error).

• SP3-320-011 (Vsg Error Counter)
• SP3-320-013 (Vsg Upper Threshold)
• SP3-320-014 (Vsg Lower Threshold)
• The above SPs can only be accessed from Special Service mode.

Agitating the Developer

This step agitates the developer, and gets the TD sensor output.

The developer agitation time is determined by the three factors below.

1. The change of absolute humidity
2. Non-use time
3. Coverage

Creating patterns, detecting the density

Five patterns are created by adjusting the charge/development bias on the transfer belt for each color. Then the ID sensor detects the created patterns.

The ID sensor consists of an LED and two types of photo detector. The sensor detects the reflection from the LED [B] with the direct reflection detector (REG) [A] and the diffused reflection detector (DIF) [C].

Determining Vtref from the Development Gamma

Detecting the development gamma value with an ID sensor pattern and measuring Vsp/Vsg determines the charge/development bias for the correct image density.

Also, the reading from the TD sensor and the development gamma determine Vtref, which is the reference value for the TD sensor.

LD Power Control

LD Control is set with SP3-600-001 (Process Control/ Select ProCon: LD Control).

• If SP 3-600-001 is set to LD Power Control by Process Control (Default): The LD strength is adjusted based on a table which is determined by Development Bias Control and Vtref Correction.
• If SP 3-600-001 is set to use a fixed LD power, the LD power that is used depends on the settings of SP2-221-001/002/003/004.

Toner Supply Control

SP3-400-001, -002, -003, -004

0: Fixed supply method

2: PID method

4: DANC method (Default)

• Fixed Supply method
  Toner supply time is calculated based on the supply rate of SP3-440-001 through -004 (DrvTime: Setting).
• PID method
  PID (Proportion Integral Differential)
  The amount of toner supply is calculated based on the pixel information and TD sensor information.
• DANC method
  DANC (Divided Active Noise Control): Conventional PID method + active noise control. It controls the timing to supply the developer to minimize uneven developer density in the development unit.

Toner Near End, Toner End

Toner Near-End

First, the amount of remaining toner is detected with the pixel count and the driving time of the toner supply motor. Then, when the amount of remaining toner is less than the threshold for toner near-end (K = 23 g, CMY = 10 g), the machine determines a toner near-end.

For CMY, when the amount of remaining toner is less than 50 g, or when the toner end sensor, which is a piezoelectric sensor, detects toner near-end twice, the machine also determines a toner near-end.

Toner End

A toner end is detected when the toner end sensor detects the end threshold six times in the toner near-end condition.

The machine also detects a toner end when the difference of the Vt and Vtref, and their total difference are as in the following matrix:

When you open and close the front door, and turn the main power off and on, the machine detects that a new toner bottle is set. The machine then starts the toner supply to recover from the toner end. After supplying toner, the machine checks the toner end sensor and Vt condition and deactivates the toner end condition.

Developer Initial Setting

When a new PCDU is set in the machine, the machine automatically detects it and enters the developer initial setting mode. The machine then detects the count which is an output from the TD sensor. The developer initial setting is done as follows.

1. Starting the developer initial setting mode
   The new unit detection mechanism triggers the developer initial setting mode.
2. Agitating the developer
   The machine rotates the development roller and transport coil to agitate the developer for 30 seconds.
3. Detecting the count (Initial value)
   While agitating the developer, the machine detects the output from the TD sensor, and stores this output as the initial count.
4. Calculating Vt
   The machine calculates Vt using the difference of the current count while referring to the initial count through SP.
5. Forced toner supply (only when newly installing the machine)
   This step is required only when the machine is newly installed because there is no toner in the toner transport route.

When the developer initial setting is successfully completed, the machine stores the calculated Vt as Vtref. The Vtref is used as a reference the next time the machine performs an initial developer setting.

SC360-01 through -04 appears if the results of step 3 are as follows:

The count is equal or exceeds the threshold (6480 [counts]).

The count does not match the target threshold (5800 – 6380 [counts]) three times consecutively.

Process Control and MUSIC are forcibly done after developer initial setting when a PCDU is replaced.