Color QSU Technology by Direct Heating System
The Direct Heating (DH) Fixing System significantly reduces heat required for the fusing roller while improving the efficiency of heat transfer. Heating the fusing roller directly with a halogen heater made this possible to reconcile energy saving and high definition, without spoiling the user-friendliness of multifunction copiers.
The fourth generation QSU achieves start-up time of 9.1 seconds and a 22% improvement in TEC value
In energy saving of a multifunction copier, it is important to reduce power consumption at standby, which is said to be about 90% (*1) per day. Consequently, "energy-saving mode" was spawned to automatically shift to a power-save status when a certain time passes while the device remains idle. QSU (Quick Start-Up) is a technology to quickly recover a multifunction copier to be ready for use from energy-saving mode (sleeping), but the speed required for start up depends on the time required to warm the fusing roller to operating temperature once it’s cold.
Ricoh has worked on developing QSU technology for more than 15 years to provide customers with energy-saving mode stress-free operation. The imagio MP C5002 (*2) with the new “color QSU technology (DH fixing system)” achieves a recovery time of 9.1 seconds (*3) from sleep (energy-saving). Typical Electricity Consumption or TEC (*4) was improved by 22% to 2.34kWh from 3.01kWh, compared with conventional devices; this reduced power consumption significantly.
Challenge a fixing technology to provide immediate warm up and transfer heat efficiently
Ricoh has evolved a fusing unit with a unique QSU technology spawned from the first generation QSU equipped on a product in 2001. It has moved to the second generation for high-speed devices and to the third generation color QSU, which adopts the IH fixing system.
The fusing unit in Figure 1 uses the fourth generation QSU technology, which eliminates the heating pipe at the inner side of the fusing roller. It adopts a new structure to warm the fusing belt directly with a halogen heater. This enabled to make a smaller diameter fusing roller (belt) with a thinner wall and to reduce heat required significantly. Beyond that, the new system uses a fixing pad to maintain contact width, rather than using the elasticity and larger diameter of the roller. It is structured to secure the necessary contact width for fixing and to keep the equivalent heat quantity given to a toner, even if the roller diameter is small.
These iterations solved issues with the third generation IH fixing system in which the configuration become oversized by such components as the magnet coil while they deliver excellent thermal efficiency. The new technology makes possible a compact fusing unit that warms up immediately, allowing efficient heat conduction. Beyond that, the in-house life cycle assessment (*5) calculated a 30% reduction of environmental impact.
Transition of QSU technology
QSU technology evolved through the following technology developments and iterations to arrive at the fourth generation.
First generation (Monochrome, middle and low-speed devices): 2001 –
The conventional fusing roller took time to warm up but did not cool down soon. In order to lower heat required for the roller, we reduced the thickness of roller wall and also developed a technology to equalize temperature distribution by controlling multiple heaters. Further, to improve the efficiency of heat transmission, we adopted a sponge pressure roller and enlarged contact width of the fusing roller with the paper. The start-up time, which was 30 seconds with conventional devices, was shortened to achieve the first in the world start-up time of 10 seconds with a monochrome device.
Second generation (Monochrome, high-speed devices): 2003 –
The first generation thin-wall fusing roller was easy to warm up and easy to cool down, so when high speed printing of 75 sheets a minute is done, the heat of the fusing roller west out with the paper. This makes it impossible to maintain copying quality and processing speed. As a remedy, we used electric storage capacitor technology capable of fast charge and discharge. Electric power during standby is stored in the capacitor as auxiliary power, which is used to replenish the heat of the roller taken away by paper through an auxiliary heater. We achieved a start-up time of 10 seconds and below in high-speed devices.
Third generation (Color): 2008 -
Color devices require far greater heat than monochrome devices to fix multiple colors of toners on paper. We therefore adopted IH (electromagnetic induction heating) technology for the fusing roller itself to generate heat using magnetism, and succeeded in improving heat transfer efficiency. We achieved quick start-up time of 9.9 seconds* for the first below 10 seconds in color devices.
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