Various Control Mechanisms; Controlling The Speed Of The Fixing Unit; Fixing Temperature Control; Speed Control On Small Size Paper (Throughput Down Control) - Canon LBP5050 Series Service Manual

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Service manual (104 pages)

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Table of Contents

- Thermal fuse (FU1): Prevents the fixing heater temperature from rising abnormally high

The thermal fuse is located at the center of the fixing heater.

If the temperature of the fixing heater rises abnormally high, the thermal fuse blows to interrupt power supply to the fixing heater.

These temperature controls in the fixing unit are performed by the fixing control circuit and the fixing heater safety circuit according to the commands from the DC

controller.

2.6.2 Various Control Mechanisms

2.6.2.1 Controlling the Speed of the Fixing Unit

2.6.2.1.1 Speed control on small size paper (Throughput down control)

LBP5050N / LBP5050

This is the control to prevent the overheating at the edge of the fixing heater when continuously printing the smaller width paper than A4 size.

When continuously printing the smaller width paper than 210mm (A4 size), the machine slows down the throughput by extending the paper pickup interval

according to the number of print.

Paper type

Plain paper (75 to 90 g/m2)

Thin paper (60 to 74 g/m2)

Thick paper (91 to 120 g/m2)

Thick paper (121 to 163 g/m2)

2.6.2.2 Fixing Temperature Control

2.6.2.2.1 Fixing temperature control

LBP5050N / LBP5050

The fixing control circuit brings the fixing heater temperature at the targeted temperature.

Fixing unit

Fixing film unit

Pressure

FU1: Temperature fuse

TH802:Thermistor

The DC controller monitors the FIXING HEATER TEMPERATURE (MAINTH) signal and sends the FIXING HEATER DRIVE (FSRD+, FSRD-) signals ac-

cording to the detected temperature. The fixing heater drive circuit controls the fixing heater depending on the signals so that the heater remains at the targeted

temperature.

1) Warm up temperature control

This control is to warm up the fixing heater until the fixing temperature reaches the required fixing temperature.

Warm up temperature differs depending on the elapsed time from the previous print, paper type or environment.

2) Print temperature control

This control is to keep the fixing sleeve temperature at a targeted temperature during printing.

CPU changes the target temperature corresponding to the number of print step-by-step. Target temperature differs depending on paper type.

Setting on driver

Plain paper

Plain paper L

Think paper 1

Thick paper 2