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AssigneeRicoh Company, Ltd.
InventorsJun Yura, Takashi Fujita, Hirokazu Ikenoue, Atsushi Nakafuji
Estimating the term…
A fixing device for forming a toner image formed on a recording medium includes a heat roller accommodating a halogen heater. The halogen heater includes a glass tube formed of transparent quartz and provided with a wall thickness of 0.8 mm or below to increase transmission thereof. The increased transmission reduces a heat loss ascribable to the glass tube at the time of warm-up of the fixing device. The heat roller has such a thermal capacity that it can be warmed up in 10 seconds or less. The glass tube is filled with inactive gas whose major component is krypton or xenon. A tungsten filament accommodated in the glass tube has its diameter reduced in order to implement a color temperature of 2,500 K or above. An image forming apparatus using the fixing device is also disclosed.
In a halogen heater comprising a glass tube filled with inactive gas and a halogen substance, said glass tube has a mean transmission of 94% with respect to light having a wave length of 300 nm to 3,000 nm.
In a halogen heater comprising a glass tube filled with inactive gas and a halogen substance, said glass tube has a wall thickness of 0.8 mm or below.
In a halogen heater comprising a glass tube filled with inactive gas and a halogen substance, said glass substrate is formed of transparent quartz made from crystal.
In a halogen heater comprising a glass tube filled with inactive gas and a halogen substance, said inactive gas contains either one of krypton and xenon as a major component.
In a halogen heater comprising a glass tube filled with inactive gas and a halogen substance, said glass tube is formed of transparent quartz made from crystal and has a wall thickness of 0.8 mm or below.
A fixing device comprising:
A fixing device comprising:
A fixing device comprising:
A fixing device comprising:
In an image forming apparatus including a fixing device comprising a heat roller accommodating a halogen heater, which comprises a glass tube filled with inactive gas and a halogen substance, and a press roller pressed against said heat roller, said glass tube has a mean transmission of 94% with respect to light having a wavelength of 300 nm to 3,000 nm.
In an image forming apparatus including a fixing device comprising a heat roller accommodating a halogen heater, which comprises a glass tube filled with inactive gas and a halogen substance, and a press roller pressed against said heat roller, said glass tube has a wall thickness of 0.8 mm or below.
In an image forming apparatus including a fixing device comprising a heat roller accommodating a halogen heater, which comprises a glass tube filled with inactive gas and a halogen substance, and a press roller pressed against said heat roller, said glass tube is formed of transparent quartz made from crystal.
In an image forming apparatus including a fixing device comprising a heat roller accommodating a halogen heater, which comprises a glass tube filled with inactive gas and a halogen substance, and a press roller pressed against said heat roller, said glass tube is formed of transparent quartz made from crystal and has a wall thickness of 0.8 mm or below.
In a fixing device comprising a hollow cylindrical member to be heated that accommodates a radiation heat source, a temperature of said member to be heated rises to a set temperature in 10 seconds or less while a color temperature of said radiation heat source is 2,500 K or above in a steady state.
In a fixing device comprising a hollow cylindrical member to be heated that accommodates a radiation heat source, a temperature of said member to be heated rises to a set temperature in 10 seconds or less, a rated voltage of 120 V is applied to said radiation heat source, and a color temperature of said radiation heat source is 2,500 K or above in a steady state.
In a fixing device comprising a hollow cylindrical member to be heated that accommodates a radiation heat source, there holds a relation:
In an image forming apparatus including a fixing device comprising a hollow cylindrical member to be heated that accommodates a radiation heat source, a temperature of said member to be heated rises to a set temperature in 10 seconds or less while a color temperature of said radiation heat source is 2,500 K or above in a steady state.
In an image forming apparatus including a fixing device comprising a hollow cylindrical member to be heated that accommodates a radiation heat source, a temperature of said member to be heated rises to a set temperature in 10 seconds or less, a rated voltage of 120 V is applied to said radiation heat source, and a color temperature of said radiation heat source is 2,500 K or above in a steady state.
In an image forming apparatus including a fixing device comprising a hollow cylindrical member to be heated that accommodates a radiation heat source, there holds a relation:
In a fixing device comprising a member to be heated that accommodates a radiation heat source, said radiation heat source comprises a glass tube accommodating a filament and filled with at least inactive gas whose major component is lower in heat conductivity than argon.
In a fixing device comprising a member to be heated that accommodates a radiation heat source, said radiation heat source comprises a glass tube accommodating a filament and filled with at least inactive gas whose major component is higher in molecular weight than argon.
In an image forming apparatus including a fixing device comprising a member to be heated that accommodates a radiation heat source, said radiation heat source comprises a glass tube accommodating a filament and filled with at least inactive gas whose major component is lower in heat conductivity than argon.
In an image forming apparatus including a fixing device comprising a member to be heated that accommodates a radiation heat source, said radiation heat source comprises a glass tube accommodating a filament and filled with at least inactive gas whose major component is higher in molecular weight than argon.
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Backward citations are indexed for grants only.
Using contact heat: structural details of heat elements, e.g. structure of roller or belt, eddy current, induction heating
Electrography
Term end not estimated
The present invention relates to a copier, printer, facsimile apparatus or similar imago forming apparatus and more particularly to a fixing device included in an image forming apparatus for fixing a toner image on a recording medium by using a halogen heater as a heat source.
A copier, for example, electrostatically forms a latent image representative of a document image on a photoconductive element or image carrier, develops the latent image with developing means to thereby produce a corresponding toner image, and transfers the toner image to a paper sheet or similar recording medium. The copier then fixes the toner image on the paper sheet with a fixing device including a heat roller. The fixing device generally uses a halogen heater or similar radiation heater or radiation heat source. The radiation heater includes a glass tube accommodating a tungsten filament and filled with inactive gas, which is generally nitrogen, argon or krypton. This kind of fixing device is low cost, safe and long life and extensively used in various image forming apparatuses including a copier.
The above-described type of fixing device includes a heat roller and a press roller pressed against the heat roller. While a paper sheet is passed through a nip between the heat roller and the press roller, a toner image carried on the paper sheet is fixed by heat and pressure. The halogen heater is accommodated in the heat roller in order to heat the heat roller by radiating heat. This kind of heating system is generally referred to as an indirect heating system. In a direct heating system the heat roller is provided with a heat generating layer on its inner or outer periphery, so that the surface of the roller generates heat. The indirect heating system needs a longer period of time for the heat roller to be warmed up to a preselected fixing temperature than the direct heating system.
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken with the accompanying drawings in which:
FIG. 1 is a graph showing the warm-up characteristic of a halogen heater;
FIG. 2 is a graph showing a relation between the temperature elevation of a conventional heat roller included in an energy saving type of fixing device and having a thin wall, the temperature elevation of a glass tube included in a halogen heater, and power input to the halogen heater;
To better understand the present invention, why a fixing device using a halogen heater needs a long warm-up time will be described with reference to FIGS. 1 through 3. FIG. 1 shows the warm-up characteristic of a halogen heater. As shown, it takes almost 2 seconds (about 1.7 seconds) for the output of a halogen heater to reach a 90% output since the turn-on of a power source. This period of time is necessary for a filament itself to be stabilized at a color temperature. Such a warm-up time is dependent on the thermal capacity, i.e., volume of the filament and decreases with a decrease in the diameter and length of the filament.
A warm-up time to a fixing temperature has been as long as about several ten seconds until the development of an energy saving type of fixing device achieving a warm-up time of about 10 seconds. In this sense, the warm-up time of about 1.7 seconds necessary for the heater itself to reach the fixing temperature may be short. However, the ratio of the period of time of about 1.7 seconds to the about 10 seconds of warm-up time of the energy saving type of fixing device is great. In this respect, there is roam for improvement in further reducing the warm-up time to less than 10 seconds.
Assume an energy saving type of fixing device using a heat roller having a small wall thickness. FIG. 2 shows a relation between the temperature elevation of a core included in the heat roller, the temperature elevation of a glass tube included in a halogen heater, and power input to the halogen heater. As shown, the temperature elevation is slow for about 1 second since the turn-on of a power source. This period of time is necessary for tungsten forming a filament to be heated to about 2,500K. During this period of time, power rises because the resistance of tungsten depends on temperature (PTC characteristic). The filament color temperature in the subsequent range where power is stabilized is set as a rated color temperature.