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.
In energy saving for multifunction copiers, 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 time required for startup depends on the time required to warm the fusing roller to operating temperature once it's cold.
*1: Assuming a 40 sheet/min device operated 20 days in an office, outputting 50,000 sheets monthly.
Ricoh has worked on developing QSU technology for more than 15 years to provide customers with energy-saving mode stress-free operation. The "RICOH MP C6003/C5503/C4503/C3503/C3003" (*2) with "the 4th generation color QSU technology (DH fixing system)" using direct heat system have shortened recovery time from a sleep mode sharply to some 5 seconds, besides achieving an industry top level energy saving (*4) in standard power consumption (TEC value) (*3). (For details on environmental performance for every model, see our product page.)
*2: The result after using the Color PxP-EQ Toner, which achieved low-temperature fixing, a smart position motor, and a low-power driven application specific integrated circuit (ASIC).
*3: The value is measured according to the method determined by the International Energy Star Program
*4: As of June 22, 2013, based on studies by Ricoh
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 haloge
*5: To assess the degree and type of environmental impact quantitatively, from resource extraction of raw material for manufacture through the manufacturing process, transportation, sales, use, maintenance, recovery and disposal.
n 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.
QSU technology evolved through the following technology developments and iterations to arrive at the fourth generation.
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.
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.
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.
*imagio MP C3301/C2801 (Released in 2010).