JP2004170692A - Image forming apparatus and heat source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus and a heat source having improved heat efficiency by suppressing a heat loss due to the occurrence of convection caused by a high temperature, in addition to this, capable of securing a satisfactory safety against firing etc., even in the case of a fixing device using a direct radiation heat source. <P>SOLUTION: As for the fixing device wherein a moving body to be heated as a member containing organic materials having a low thermal conductivity is heated by the heat source 10 equipped with a member for emitting light in accordance with the power supply, the heat source 10 is turned on while making a lighting ratio or a lighting voltage variable, and also, the fixing device is provided with a heat insulating space layer 14 arranged between the heat source 10 and the fixing roller 1, and a glass plate 15 for forming the heat insulating space layer 14. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus having a fixing device and a heat source.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a fixing device used in an image forming apparatus, a fixing device that directly fixes by heating from a heat source whose temperature rises rapidly is known. In such a fixing device, contact heating in which a heat source is in contact is also conceivable. However, non-contact heating using a radiant heat source is effective in consideration of long-term stability such as contamination of the heat source and contamination of an object to be heated.
[0003]
However, non-contact heating with a radiant heat source has a fundamental disadvantage of poor thermal efficiency. That is, since radiant heating is non-contact, there is a space between the heat source and the object to be heated, and to heat the moving object to be heated, the space must have an inlet and an outlet for the moving object. The convection heat due to the high temperature of the radiant heat source is released to the outside from these open portions, and the heating efficiency is deteriorated.
[0004]
In addition, as a member / part of the object to be heated by direct heating,
1. Heat the surface of the paper.
2. The surface of the heat-insulating fixing member is heated.
3. A flexible fixing member such as a belt is heated.
4. Heat toner and ink.
[0005]
[Problems to be solved by the invention]
However, in the applications 1 to 4, the object to be heated is mainly an organic substance having a low thermal conductivity, such as cellulose, fluororesin, silicone rubber, and polyester resin. There are points. Further, even when the metal belt or the sleeve is a base material, the same applies to a case where a rubber or resin layer is formed on the base material.
[0006]
The first point is heating without temperature unevenness.
When the lighting of the heat source is not continuous, unless the lighting interval is sufficiently small with respect to the heating time (heating width / moving speed of the object to be heated), striped temperature unevenness in a direction perpendicular to the moving direction occurs. .
[0007]
In the case of continuous lighting, unless the irradiation power itself is variable, the temperature of the object to be heated will not be constant due to a change in the temperature of the surrounding members, causing temperature unevenness.
The second point is to avoid ignition and smoking of the object to be heated.
[0008]
Ignition of the object to be heated occurs when it comes into contact with a heat source. Since the energy from the radiant heat source is transmitted to the object to be heated with a difference of the fourth power of the absolute temperature, the radiant heat source has a very high temperature of at least 1000 ° C. Therefore, when an object to be heated such as an organic substance or a peripheral member comes into contact with a heat source due to some abnormality, it is easily ignited.
[0009]
Further, ignition of the object to be heated occurs when the object to be heated is stopped. Only when the input energy of the radiant heat source is large, this is the case where the heating time of the heated object can only be shortened, but because the temperature rises instantaneously while moving, if the heated object stops due to some abnormality, Because it receives radiant energy for a long time, it becomes high temperature and leads to ignition.
[0010]
Due to such a problem, a fixing device using a direct radiant heat source has not been adopted in recent image forming apparatuses due to danger such as ignition.
The present invention solves the above-mentioned conventional problems, and even in a fixing device using a direct radiant heat source, suppresses heat loss due to convection generated due to high temperature and has good thermal efficiency, and in addition to ignition, etc. An object of the present invention is to provide an image forming apparatus and a heat source that can ensure sufficient safety.
[0011]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides an image forming apparatus having a fixing device that heats an object to be heated, which is a member containing an organic substance having a low thermal conductivity and moved by a heat source having a member that emits light when energized. The heat source is turned on with a variable lighting ratio or a variable lighting voltage, and a heat insulating space layer and a transparent member forming the heat insulating space layer are provided between the heat source and the object to be heated.
[0012]
In addition, the present invention is effective when an energization control unit that shuts off the lighting of the heat source substantially in synchronization with the stop of the object to be heated is provided.
Further, the present invention is effective when the heat insulating space layer is at least a substantially sealed air layer at atmospheric pressure.
[0013]
Furthermore, the present invention is effective when the heat insulating space layer is a closed gas layer.
Furthermore, the present invention is effective when the gas layer is filled with a gas mainly containing argon, krypton, and xenon.
[0014]
Furthermore, the present invention is effective when the heat-insulating space layer is a depressurized gas layer.
Furthermore, the present invention is effective when the heat insulating space layer is an air layer to be exhausted.
[0015]
Furthermore, the present invention is effective when the heat insulation space layer includes the heat source.
Still further, the present invention is effective when a reflecting means for reflecting the radiation from the heat source toward the object to be heated is provided.
[0016]
Furthermore, the present invention is effective when the reflection means is a reflection film provided on the outer surface of the heat source.
Furthermore, the present invention is effective when the reflection film contains gold as a main component.
Still further, according to the present invention, the heat source includes a glass tube filled with an inert gas, and a filament as a member that emits light when energized, wherein only the inert gas is filled in the glass tube, Is effective if it is made of tungsten.
[0017]
Furthermore, the present invention is effective when the inert gas contains xenon and krypton as main components.
Still further, according to the present invention, the heat source has a glass tube filled with an inert gas, and a filament made of tungsten as a member that emits light when energized. The inert gas contains xenon and krypton as main components. It is effective if a gas containing a small amount of a halogen compound is sealed.
[0018]
Still further, the present invention is effective when the heat source includes a filament mainly composed of carbon.
Furthermore, the present invention is effective when the heat source heats the fixing member.
[0019]
Furthermore, the present invention is effective when the heat source heats the belt.
Furthermore, the present invention is effective when the heat source directly heats the toner.
[0020]
Furthermore, the present invention is effective when the heat source heats a recording medium.
Furthermore, the present invention is effective when the heat source is configured as a unit that can be separately replaced with a fixing unit having the fixing member or the fixing belt.
[0021]
In order to solve the above-mentioned problems, the present invention provides a heat source used for a fixing device in an image forming apparatus, in which a filament that generates heat by energization is sealed in a glass tube together with a sealing gas containing at least an inert gas. It is sealed in a glass tube having a diameter, and a heat insulating layer of a low-pressure gas is provided between the glass tube and the large-diameter glass tube.
The present invention is effective when the large-diameter glass tube has a plurality of heat sources sealed therein, and the plurality of heat sources are integrated with a glass tube in which a filament is sealed.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory diagram showing one embodiment of the present invention.
[0023]
In FIG. 1, reference numeral 1 denotes a fixing roller as a fixing member, 2 denotes a pressing roller pressed against the fixing roller, and the fixing roller 1 is rotationally driven in a direction indicated by an arrow by driving means (not shown). The roller 2 is driven and rotated. The fixing roller 1 is formed by laminating a release layer 5 on the outer periphery of a metal core 3 as a base material via a heat insulating rubber layer 4, while the pressing roller 2 is formed by laminating a rubber layer 7 on the outer circumference of a metal core 6. The release layer 8 is covered through the intermediary. Note that the rubber layer 4 of the fixing roller 1 can be omitted when the demand for image uniformity quality is low. Further, the base material is not limited to the metal core 3, but may be a thin metal sleeve or a resin belt. Even when such a low heat capacity base material is used, the heat insulating rubber layer 4 can be omitted. . Furthermore, the function of the heat insulating rubber layer 4 can be exerted even if it is a laminate of two or more layers divided into a heat insulating layer and a rubber layer.
[0024]
A heat source 10 is provided outside the fixing roller 1, and the surface of the fixing roller 1 is heated by the heat source 10. The heat source 10 is configured by arranging a filament 12 as a member that emits light when energized in a glass tube 11 and filling an inert gas. The heat source 10 is inclined at a U-shaped cross section with the surface facing the fixing roller 1 opened. It is arranged in a reflection plate 13 as a reflection member having a bent shape. A glass plate 15 as a transparent member forming a heat insulating space layer 14 is attached to the open surface of the reflection plate 13.
[0025]
The heat insulating space layer 14 formed by mounting the glass plate 15 is a closed space by closing both sides of the heat source 10, so that convection generated by high temperature is prevented from escaping to the outside air, and thermal efficiency is reduced. Can be enhanced. Furthermore, in such a configuration, the heat insulating space layer 14 exists between the radiant heat source 10 and the fixing roller 1 which is the object to be heated in this example, so that a heat insulating effect of suppressing a temperature rise on the outer surface side of the glass plate 15 can be obtained. . Note that the glass plate 15 is preferably as thin as the strength permits, in order to eliminate slight radiation heat absorption.
[0026]
In the fixing device configured as described above, the heat source 10 heats the fixing roller 1 in synchronization with the arrival of the sheet P as the recording medium carrying the unfixed toner image at the nip between the fixing roller 1 and the pressure roller 2. The heat and the pressure between the rollers act to fix the toner on the paper P.
[0027]
The heating of the object to be heated by the heat source 10 is required to be controlled at a constant temperature so as not to cause temperature unevenness. In the present embodiment, the energization of the heat source 10 is turned on with a variable lighting ratio. Specifically, the power supply to the heat source 10 is performed while rotating the fixing roller 1. When the temperature is raised from room temperature to 160 ° C., the AC 100 V is continuously supplied, and immediately before the temperature reaches 160 ° C., the AC 100 V is switched at 100 Hz to 20 kHz. By setting the lighting ratio to 50 to 100%, the heating temperature can be maintained at 160 ° C. ± 5 ° C. Further, even when the energization of the heat source is performed by varying the lighting voltage, good control without temperature unevenness can be performed as in the case of varying the lighting ratio. In this case, the AC voltage itself may be varied between 70V and 100V, and the DC voltage may be varied between 70V and 100V.
[0028]
When the heat source 10 is energized, the fixing roller 1, which is the object to be heated, is restricted during rotation, but it is indispensable to prevent problems such as ignition and smoke. For this reason, a means for detecting the rotation of the fixing roller 1 is provided to detect the stop of the rotation of the fixing roller 1 and synchronously cut off the power supply to the heat source 10. Generally, a means for detecting the rotation of the fixing roller 1 uses a rotary encoder or an optical sensor. However, since these detecting means use a semiconductor which may be broken, it is necessary to pay sufficient attention to durability. is there.
[0029]
Therefore, in the present embodiment, a power generation unit that generates electric power by using a drive that moves the object to be heated is provided, and the power generation unit is configured to supply power to the heat source 10. To shut off the current. Specifically, as shown in FIG. 2, an on / off relay 21 that is turned on / off by the electromotive force is provided in the electromotive force generation circuit of the DC motor 20 that drives the fixing roller 1 in opposition to the DC motor 20. . The electric circuit having the on / off relay 21 includes a power supply unit 22, a heat source 10, a temperature sensor 23, a temperature regulator 24, a thermostat 25, and the like. When the DC motor rotates, the on / off relay 21 is turned on, and the heat source 10 can be energized. On the other hand, when the rotation of the DC motor is stopped, the on / off relay 21 is turned off because no electromotive force is generated in the electromotive force generating circuit. In this off state, the heat source 10 is not energized.
[0030]
With this configuration, if the fixing roller 1 is in the stopped state, the heat source 10 is not energized because the on / off relay 21 does not operate. That is, power is generated by rotating the fixing roller 1 and power is supplied only by activating the on / off relay 21 based on the voltage. Therefore, even if a component other than the on / off relay 21 fails, the heat source 10 is not supplied. If the ON / OFF relay 21 breaks down, it is energized. However, as long as an ON / OFF relay 21 that has obtained safety standards such as UL and CSA is used, the safety of the device is basically guaranteed. Durability can be obtained.
[0031]
FIG. 3 is an explanatory cross-sectional view showing another embodiment of the present invention. In this embodiment, a fixing device for heating a fixing roller from the inside is shown.
In FIG. 3, the object to be heated according to the present embodiment is also a fixing roller 30. The fixing roller 30 includes a 0.4 mm thick aluminum thin sleeve 31 and a rubber layer 32 and a release layer 33 made of Teflon (trade name). It is a laminate. The heat source 10 is provided inside the fixing roller 30, and the outside is covered with a glass tube 16 as a transparent member, and is configured like a double tube. The outer glass tube 16 is preferably as thin as the strength permits, in order to eliminate slight radiant heat absorption.
[0032]
In the fixing device configured as described above, since the heat source 10 is covered with the glass tube 16 so as to form the heat-insulating space layer 14 that is substantially sealed between the heat source 10, the filament 12 is covered with the double glass tube. And the convection of heat is suppressed, and the thermal efficiency is increased. In this embodiment, the heat insulating space layer 14 between the heat source 10 and the outer glass tube 16 can provide the heat insulating effect of suppressing the temperature rise on the outer surface side of the glass tube 16. It does not need that effect.
[0033]
FIG. 4 is an explanatory sectional view showing still another embodiment of the present invention. In this embodiment, the fixing device heats a fixing belt from the inside.
In FIG. 4, a fixing belt 40 is used as an object to be heated, and the fixing belt 40 is configured by covering a rubber substrate 42 and a Teflon layer 43 on a polyimide base material 41. A fixing member 44 is provided inside the belt facing the pressure roller 2, and the fixing belt 44 and the pressure roller 2 are in contact with each other at a predetermined pressure by the fixing member 44. The heat source 10 covered with the glass tube 16 is provided in the fixing belt 40 with the heat insulating space layer 14 interposed therebetween.
[0034]
In the fixing device configured as described above, the heat source 10 is covered by the glass tube 16 via the heat-insulating space layer 14 that is substantially closed, so that the filament 12 has a structure in which the filament 12 is covered by a double glass tube. Convection is suppressed and thermal efficiency is increased. Although the fixing belt 40 is rotated by a driving unit (not shown), if the fixing belt 40 is intentionally cut and broken and rotated, a part of the belt contacts the heat source side. In this experiment, no problem occurred due to the heat insulating effect of the heat insulating space layer 14 in the heat source having the double tube structure of the present embodiment, but when a general single tube heat source other than the double tube was used, smoke was generated from the contact portion. Occurred.
[0035]
FIG. 5 is an explanatory cross-sectional view showing still another embodiment of the present invention. This embodiment is a system for heating toner with a heat source.
In FIG. 5, a transfer fixing belt 53 is provided facing an intermediate transfer body 51 to which a toner image is transferred from a photoconductor 50. The transfer fixing belt 53 is formed by coating a rubber substrate 55 and a Teflon layer 56 on a polyimide base material 54, and a fixing member 57, a radiant heat source 58, and a transfer member 59 are provided inside the belt. The fixing member 57 is opposed to the pressure roller 2, and the transfer fixing belt 53 and the pressure roller 2 are in contact with each other with a predetermined pressure. Outside the transfer fixing belt 53, there is provided a heat source 10 disposed in a reflection plate 13 as a reflection member having a shape of a cross-section U having an open face and having a slanted cross section. A glass plate 15 as a transparent member forming the heat insulating space layer 14 is attached to the open surface of the reflection plate 13.
[0036]
In this system, the toner on the intermediate transfer body 51 is not paper but the toner transferred on the transfer fixing belt 53 is sufficiently heated and then pressed against the paper. In this system, it is possible to control both the temperature of the toner upper layer portion which becomes the upper surface of the image after fixing and the temperature of the toner lower layer / paper interface. Since the toner lower layer / paper interface temperature can be controlled by directly heating the toner and / or by heating the paper, the direction of the reflector 13 of the heat source 10 is adjusted to heat only the toner and heat only the paper. It is possible to heat the two simultaneously at an appropriate ratio by using one heat source 10. In this case, the heat source 10 is also excellent in heat transfer and safety can be secured by disposing the glass plate 15.
[0037]
FIG. 6 is an explanatory cross-sectional view showing still another embodiment of the present invention. This embodiment is a system for heating toner and paper with a heat source.
In FIG. 6, a fixing belt 60 is formed by coating a rubber layer 62 and a Teflon layer 63 on a polyimide base material 61. A fixing member 64 and a radiant heat source 65 are provided inside the belt. The fixing member 64 is opposed to the pressure roller 2, and the fixing belt 60 and the pressure roller 2 are in contact with each other with a predetermined pressure. A heat source 10 disposed in the reflection plate 13 is provided near the nip between the fixing belt 60 and the pressure roller 2 and on the upstream side in the transport direction of the sheet P as a recording medium. The reflecting plate 13 is formed in a shape in which the cross section U whose surface on the paper P side is opened is inclined, and a glass plate 15 as a transparent member forming the heat insulating space layer 14 is attached to the open surface of the reflecting plate 13. ing.
[0038]
Also in the fixing device having such a configuration, the glass plate 15 forming the heat insulating space layer 14 is disposed on the reflection plate 13, so that excellent heat transfer and sufficient safety can be ensured. Further, the fixing device is downsized. The heating amount of the heat source 10 can be adjusted according to the type of paper.
[0039]
The fixing device has a closed configuration including both ends of the heat source 10 so that the heat insulating space layer 14 formed by the transparent member forms a closed space. At the time of sealing, it is important to select a material that absorbs the difference in linear expansion between the heat source 10 and the glass of the transparent member at both ends of the heat source 10, and glass, ceramic, metal, or the like can be used alone or in combination. In order to obtain such a closed structure, the glass plate 15 may be a double glass plate having a space formed therein as shown in FIG. 7, or a glass tube 16 may be formed in the space as shown in FIG. When the double glass tube is formed in which is formed, it is effective against a difference in linear expansion. Further, the glass plate 15 and the glass tube 16 having the double structure have an advantage of further enhancing the heat insulating effect.
[0040]
By the way, the heat insulating space layer 14 formed by the glass plate 15 and the glass tube 16 is advantageous in terms of heat efficiency and safety due to a heat insulating effect when a reduced pressure gas layer, that is, a vacuum is used. In this case, it is difficult to make the heat insulating space layer 14 a complete vacuum, but it can be said that the closer to the complete vacuum, the more preferable. In addition, encapsulating a polymer gas containing argon, krypton, and xenon as main components in the heat insulating space layer 14 is also effective in terms of thermal efficiency and safety due to the heat insulating effect. Furthermore, although the heat insulating space layer 14 is not hermetically sealed, an inlet and an outlet may be provided in the closed space layer, and external air may flow in from the inlet, and may be exhausted from the outlet. In such a configuration, the thermal efficiency is deteriorated, but the safety is effective.
[0041]
The present inventor has described the thermal efficiency and safety in the case where the heat insulating space layer 14 is an open space, in the case of a closed air layer, in the case of vacuum, in the case of polymer gas sealing, in the case of flowing air. Experiments to compare were performed.
[0042]
As a result, vacuum was the best in terms of thermal efficiency, followed by polymer gas, closed space, open space, and air flow. In terms of safety, vacuum was the best, followed by air flow, polymer gas, open space, and closed space. However, in terms of safety, the heat insulating layer is most easily maintained in the open space in the long term, followed by the air flow, the closed space, the polymer gas, and the vacuum.
[0043]
By the way, the reflector 13 is effective in increasing the thermal efficiency of the heat source 10, but it is difficult to install the reflector 13 when the heat insulating space layer 14 is formed by the glass tube 16. Therefore, in the apparatus for forming the heat insulating space layer 14 with the glass tube 16, as shown in FIG. 9, the reflection film 13a is formed on a part of the outer surface of the glass tube 11 of the heat source 10 by painting, vapor deposition, or the like. The heat efficiency of the heat source 10 configured as described above is improved, and the heat efficiency is further improved as compared with the case where the reflection film 13a is arranged by attaching the heat source 10 or the like.
[0044]
When the efficient arrangement of the reflectors was examined, it was found that by applying a reflective coating on the outer surface of the heat source 10, the heat efficiency was higher than when the reflector was arranged outside the heat source 10. This is probably because the reflection film 13a is smaller and closer to the heat source, so that the amount of heat absorbed without reflection can also contribute to the radiation of the heat source. Further, as a result of examining the material of the reflective film 13a, it is found that gold is the most excellent because it has a high heat resistance due to being close to the heat source 10, a high melting point, and a high reflectance with a high resistance to chemical changes such as oxidation. It has been found. Therefore, it is preferable that the reflective film 13a contains gold as a main component.
[0045]
It is also known that a high-speed printer or the like uses a plurality of heat sources having different orientation distributions of heat generation width in order to maintain temperature uniformity when using paper of various paper widths. Furthermore, it may be required to use heat sources having different wavelengths simultaneously or alternately depending on the properties of the object to be heated. Therefore, in the present invention, as shown in FIGS. 10A and 10B, a plurality of heat sources, for example, a central heat source 10a and an end heat source 10b can be arranged in one glass tube 16. . With this configuration, the plurality of heat sources 10a and 10b are included in one heat-insulating space 14, so that the device can be downsized and the number of parts can be reduced. Further, when a plurality of heat sources 10a and 10b are arranged in one glass tube 16, as shown in FIG. 11, a glass tube 11 of the heat source 10 is formed in a shape of a section 8 and integrated. The use of the tubes 11 results in a heat source structure with less glass material and excellent strength than provided independently. Further, the large-diameter glass tube 16 can be made smaller, and the entire heat source portion can be reduced in size. The number of heat sources is not limited to two, but may be three or more.
[0046]
Since the heat source 10 is turned on with a variable lighting ratio or variable lighting voltage, the halogen cycle is not stable even with a general halogen heater, and the life of the filament 12 is reduced.
[0047]
Therefore, by using a heater in which the tungsten filament 12 is sealed only with the inert gas as the heat source 10, the breaking of the filament 12 is suppressed even when lighting with a variable lighting ratio or a variable lighting voltage is performed because no halogen compound is contained. You. The inert gas is argon, more preferably xenon or krypton. Xenon and krypton are inert gases that do not chemically erode the filament even at a high temperature of 2000K, and are the largest molecules except for the radioactive element radon. The cross-sectional area is large and the evaporation of tungsten molecules in the filament can be suppressed. That is, it is possible to reduce the mean free path in which evaporated atoms of tungsten move without colliding with other atoms.
[0048]
Further, the heat source 10 may be one in which a trace amount of a halogen compound and an inert gas containing xenon and krypton as main components are sealed. Even when the heat source 10 configured as described above is turned on with a variable lighting ratio or a variable lighting voltage, the life of the filament can be extended by the effect of suppressing the evaporation of xenon and krypton and the halogen cycle using a small amount of a halogen compound.
[0049]
Further, the life of the heat source 10 can be extended by using the filament 12 mainly composed of carbon which does not easily evaporate. In addition, carbon is a heat source that emits far-infrared rays, and the thermal efficiency is increased.
[0050]
In addition, when the heat source in which the inert gas was sealed or the heat source of the carbonized filament was turned on with a variable lighting ratio or a variable lighting voltage, the life of the halogen heater was about 1000 hours, and the life was greatly extended to 5000 hours. In the configuration using carbon as the filament, the rise was slightly delayed due to the large heat capacity of carbon. However, the thermal efficiency was improved by infrared rays due to a small average power and a low color temperature during continuous paper passing.
[0051]
As described above, since the configuration in which the heat insulating space layer is provided between the heat source 10 and the object to be heated is more complicated than that of the conventional heater, the cost increases accordingly, but the heating unit having the heat source and the fixing member are required. Each of the fixing units has a separate unit, so that the fixing units can be replaced separately. Therefore, it is possible to separately replace a long-life heat source and a fixing member including a pressure roller that needs to be replaced due to heating, toner fixation, or the like, thereby reducing running costs.
[0052]
【The invention's effect】
According to the configuration of the first aspect, the heat source is turned on with a variable lighting ratio or a variable lighting voltage, and the heat source includes the heat insulating space layer and the transparent member that forms the heat insulating space layer between the heat source and the object to be heated. It is possible to suppress the occurrence of temperature unevenness in the object to be heated due to the long flashing interval of, and to greatly reduce the risk of ignition due to contact with the heat source.
[0053]
According to the configuration of the second aspect, since the power supply control means for limiting the lighting of the heat source only when the object to be heated is moved is provided, the safety is dramatically improved.
According to the configuration of the third aspect, since the heat insulating space layer is at least a substantially closed air layer at atmospheric pressure, good heat insulating properties can be maintained for a long time.
[0054]
According to the configuration of the fourth aspect, since the heat insulating space layer is a sealed gas layer, the gas layer does not easily discharge heat to the outside, so that the thermal efficiency increases.
According to the configuration of claim 5, since the gas layer is filled with a gas containing argon, krypton, and xenon as main components, the kinematic viscosity is the highest among inert gas molecules (excluding the radioactive element radon) having high safety. And convection hardly occurs, and the thermal conductivity is low. In terms of thermal conductivity, chlorine, ammonia and the like also have high heat insulating properties, but the above-mentioned gas is suitable in view of the danger of leakage at high temperatures. Therefore, the pressure difference from the outside can be reduced, and even if an impact is applied, the possibility of breakage is low, heat does not flow out, and the thermal efficiency is the highest.
[0055]
According to the configuration of the sixth aspect, since the heat insulating space layer is a depressurized gas layer, it is vacuum and has the highest heat insulating property. In addition, heat does not flow out, and the heat efficiency is highest. As compared with the case where the heat insulating space layer is made of gas, pressure increase due to expansion of the gas at the time of heating does not occur, and stable heat insulation can be obtained. Regarding the heat insulating property, it is known in air bottles and the like that the pressure is preferably 0.1 Pa or less in the case of air.
[0056]
According to the configuration of claim 7, since the heat insulating space layer is an air layer to be exhausted, convection heat is discharged, so that the heat insulating property is as high as vacuum. In addition, although the heat efficiency is slightly deteriorated because the heat is discharged to the outside, there is no pressure difference from the outside and the possibility of damage is low even if an impact is applied.
[0057]
According to the configuration of claim 8, since the heat insulating space layer contains the heat source, the smallest size and safety by heat insulation can be achieved. Also, it is possible to include two heat sources having different light distributions.
[0058]
According to the configuration of the ninth aspect, since the reflecting means for reflecting the radiation from the heat source to the object to be heated is provided, the radiant heat can be concentrated and the thermal efficiency is increased.
According to the configuration of claim 10, since the reflection means is a reflection film provided on the outer surface of the heat source, reflection is performed at a portion closest to the heat source. Therefore, a large reflection film is not necessarily required, and miniaturization is possible. , Heat loss is small.
[0059]
According to the configuration of claim 11, the heat source has a glass tube filled with an inert gas, and a filament as a member that emits light when energized, and only the inert gas is filled in the glass tube. Is made of tungsten, and therefore has a heater configuration that does not contain a halogen compound. Therefore, even if the lighting is performed with a variable lighting ratio or variable lighting voltage, the breakage of the filament is suppressed.
[0060]
According to the twelfth aspect of the invention, since the inert gas contains xenon and krypton as main components, the dependency on the halogen cycle is eliminated, and a long life can be obtained by the effect of suppressing the filament evaporation of xenon and krypton.
[0061]
According to the structure of claim 13, since the heat source is filled with a tungsten filament and a gas containing a small amount of a halogen compound mainly containing an inert gas of xenon and krypton, the filament evaporation of xenon and krypton is suppressed. The effect and the breakage of the filament can be suppressed together with the halogen cycle by a trace amount of the halogen compound.
[0062]
According to the structure of claim 14, since the heat source is provided with a filament containing carbon as a main component, the life is improved by using carbon which is less likely to evaporate than tungsten, and the carbon can be made of far infrared rays. And the heating efficiency can be improved.
[0063]
According to the configuration of the fifteenth aspect, since the heat source is the fixing device that heats the fixing member, even if a part of the fixing member attempts to contact the heat source side due to breakage or the like, it is lower than the ignition temperature insulated by the heat insulating space layer. There is no danger of fire because the transparent member prevents contact. Since the fixing surface is heated by the radiant heat, the temperature can be quickly raised, and the use of the image can be started immediately at the time of image formation.
[0064]
According to the configuration of claim 16, since the heat source is a fixing device that heats the belt, even if a part of the fixing member attempts to contact the heat source side due to breakage or the like, the transparent member is lower than the ignition temperature insulated by the heat insulating space layer. The danger of fire does not occur because the contact is prevented by the conductive member. Further, since the inner surface of the fixing member is heated by radiant heat and the temperature of the thin fixing member is increased by heat conduction, the temperature can be quickly increased, and the use of the image can be started instantaneously at the time of image formation.
[0065]
According to the configuration of claim 17, since the heat source is a fixing device that directly heats the toner, even if the toner tries to come into contact with the heat source due to scattering or the like, a transparent member lower than the ignition temperature insulated by the heat insulating space layer is used. There is no danger of fire since contact is prevented. The toner is heated by the radiant heat, so that the temperature can be quickly raised, and stable image formation is possible.
[0066]
According to the configuration of the eighteenth aspect, since the heat source is a fixing device that heats the recording medium, even if paper tries to contact the heat source side, the contact is made with a transparent member lower than the paper ignition temperature insulated by the heat insulating space layer. There is no danger of ignition because it is prevented. Since the paper surface is heated by the radiant heat, the temperature can be quickly raised.
[0067]
According to the nineteenth aspect, the heat source is configured as a separately replaceable unit with the fixing unit having the fixing member or the fixing belt. The running cost can be reduced because the secondary transfer fixing member (including the integral pressing member) can be replaced separately.
[0068]
According to the configuration of claim 20, the filament that generates heat by energization is sealed in a glass tube together with a sealing gas containing at least an inert gas, and the glass tube is sealed in a large-diameter glass tube. Since the heat-insulating layer of the low-pressure gas is provided between the tubes, it is possible to provide a heat source having a long life and high thermal efficiency.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a fixing device according to an embodiment of the present invention.
FIG. 2 is a circuit diagram of a power generation unit provided in the fixing device.
FIG. 3 is a schematic configuration diagram of a fixing device showing another embodiment of the present invention.
FIG. 4 is a schematic configuration diagram of a fixing device showing still another embodiment of the present invention.
FIG. 5 is a schematic configuration diagram of a fixing device showing still another embodiment of the present invention.
FIG. 6 is a schematic configuration diagram of a fixing device showing still another embodiment of the present invention.
FIG. 7 is an explanatory diagram showing an embodiment of the heat source of the present invention.
FIG. 8 is an explanatory view showing another embodiment of the heat source of the present invention.
FIG. 9 is an explanatory view showing still another embodiment of the heat source of the present invention.
FIGS. 10 (a) and (b) are side and front explanatory views showing still another embodiment of the heat source of the present invention.
FIG. 11 is an explanatory sectional view showing a modification of the heat source shown in FIG. 10;
[Explanation of symbols]
1,30 fixing roller
2 Pressure roller
10. Heat source
13 Reflector
14 Thermal insulation space layer
15 Glass plate
16 Glass tube
40 Fixing belt

Claims (22)

An image forming apparatus having a fixing device that heats an object to be heated, which is a member containing an organic substance having a low thermal conductivity and moved by a heat source having a member that emits light when energized,
An image forming apparatus, wherein the heat source is turned on with a variable lighting ratio or a variable lighting voltage, and further comprising a heat insulating space layer between the heat source and the object to be heated and a transparent member forming the heat insulating space layer. The image forming apparatus according to claim 1, further comprising an energization control unit that shuts off lighting of the heat source substantially in synchronization with the stop of the object to be heated. 2. The image forming apparatus according to claim 1, wherein the heat insulating space layer is at least a substantially closed air layer at atmospheric pressure. The image forming apparatus according to claim 1, wherein the heat insulating space layer is a sealed gas layer. The image forming apparatus according to claim 4, wherein the gas layer is filled with a gas containing argon, krypton, and xenon as main components. The image forming apparatus according to claim 1, wherein the heat insulating space layer is a depressurized gas layer. The image forming apparatus according to claim 1, wherein the heat insulating space layer is an air layer to be exhausted. The image forming apparatus according to claim 1, wherein the heat insulating space layer includes the heat source. The image forming apparatus according to claim 1, further comprising a reflection unit configured to reflect radiation from the heat source toward the object to be heated. The image forming apparatus according to claim 9, wherein the reflection unit is a reflection film provided on an outer surface of the heat source. 11. The image forming apparatus according to claim 10, wherein the reflection film contains gold as a main component. The heat source has a glass tube filled with an inert gas, and a filament as a member that emits light when energized, only the inert gas is filled in the glass tube, and the filament is made of tungsten. The image forming apparatus according to claim 1. 13. The image forming apparatus according to claim 12, wherein the inert gas contains xenon and krypton as main components. The heat source has a glass tube filled with an inert gas, and a filament made of tungsten as a member that emits light when energized. Xenon and krypton as the inert gas are mixed with a slight amount of a halogen compound. The image forming apparatus according to claim 1, wherein a gas is sealed. The image forming apparatus according to claim 1, wherein the heat source includes a filament containing carbon as a main component. The image forming apparatus according to claim 1, wherein the heat source heats the fixing member. The image forming apparatus according to claim 1, wherein the heat source heats the belt. The image forming apparatus according to claim 1, wherein the heat source directly heats the toner. The image forming apparatus according to claim 1, wherein the heat source heats a recording medium. The image forming apparatus according to claim 1, wherein the heat source is configured as a unit that can be separately replaced with a fixing unit having the fixing member or the fixing belt. In a heat source used for a fixing device in an image forming apparatus,
A filament that generates heat by energization is sealed in a glass tube together with a sealing gas containing at least an inert gas, and the glass tube is sealed in a large-diameter glass tube, and a heat-insulating layer of a low-pressure gas is provided between the glass tube and the large-diameter glass tube. The heat source characterized in that a heat source is provided. 22. The heat source according to claim 21, wherein a plurality of the heat sources are enclosed in the large-diameter glass tube, and the plurality of heat sources are integrated with a glass tube in which a filament is enclosed.

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