Paper Thickness, Double Feed Detection

The best conditions for image transfer and fusing depend on paper thickness and paper type. Therefore, it is important to select the correct paper thickness on the operation panel for high quality printing. Also, fusing failure or paper jam can occur if the paper thickness is different from the one selected on the operation panel.
For the above reasons, this machine has a paper thickness/double feed detection feature to prevent problems caused by selecting the wrong paper thickness on the operation panel.

Basic Operation

The paper type sensor (lever-type encoder sensor) [A] measures the thickness of the paper. Then the machine uses the measurement results to check that the paper thickness is correct and that there is no double feed. If the paper thickness is different or a double feed has occurred, the machine stops feeding the paper.

The paper type sensor [A] detects the rotation amount of the lever [B], and then checks if the paper thickness is correct and that there is no double feed.

There are two paper type sensors. One is installed in the bypass relay transport section and the other is in the relay transport section. The paper type sensor [A] in the bypass relay transport section detects the thickness of the paper transported from the bypass tray. The paper type sensor [B] in the relay transport section detects the thickness of the paper transported from the bank feed section/LCIT (option)/duplex transport section.

Paper Removal Method

If the machine detects the wrong paper thickness or a double feed, you can remove the paper in the same way as the usual jam removal operation. You need to do the following after removing the paper.

• If the machine detected the wrong paper thickness:
  Change the paper in the paper tray, so that the thickness of the paper in the tray matches the one selected on the operation panel.
  -or-
  Change the paper thickness on the operation panel, so that the paper thickness selected on the operation panel matches the one in the paper tray.
  
  
• If the machine detected a double feed:
  Fan the stack of paper in the paper tray.

Paper Thickness Detection

After the first sheet of paper reaches the paper thickness measurement section, the paper type sensor measures the paper thickness and the machine compares the measurement result and the paper thickness selected on the operation panel (Tray Setting).
If the measured thickness is not within the allowable range as shown in the table below, the machine determines that the paper thickness is wrong, and stops feeding the paper. Then J098 (JAM) is displayed on the operation panel.

Double Feed Detection

There are two types of double feed:

• The preceding sheet is double fed, but the succeeding sheet is fed normally: J095 is displayed
• The preceding sheet is fed normally, but the succeeding sheet is double fed: J099 is displayed

The machine compares the thickness of two paper sheets (preceding sheet and succeeding sheet) consecutively fed from the same paper tray. If the paper thickness difference between the two paper sheets is larger than the double-feed detection threshold, the machine detects a double feed and stops feeding the paper. Then J095 or J099 is displayed on the operation panel.
The measured paper thickness value, which is used for the double-feed judgement, is reset at the following times.

• When the main power is turned ON. (The machine resets the measured values of the paper which has been fed from all the paper trays.)
• When all the doors are closed while the main power is ON.
• When the paper tray is pulled out and inserted again. (The machine resets the measured values of the paper which has been fed from the paper tray which was pulled out and inserted again.)
• When the status of the bypass tray paper end sensor is shifted from the paper absent state to the paper present state. (The machine resets the measured value of the paper which was fed from the bypass tray.)
• When printing on paper for the first time since the paper thickness setting was changed on the operation panel. (The machine resets the measured value of the paper fed from the paper tray for which the paper thickness setting was changed.)
• When a double feed occurs. (The machine resets the measured value of the paper transported from the paper tray in which the double feed occurred)
• When a paper jam occurs.
• After returning from the energy saving mode.