JPH04337785A - Heating roller device - Google Patents

Abstract

PURPOSE:To enable the heat generation distribution in the axial direction of a heating means to be freely changed and controlled by constituting the means in such a manner that at least two pieces of plural heating elements consisting of parts varying in calorific value can be independently energized. CONSTITUTION:The heating elements 51 to 53 are disposed in the heating means disposed axially in the cylinder of the heating roller. The heating element 51 emits light by having the calorific value H10 over a length L12. The heating element 52 is constituted of the part of a length L13 having the calorific value H11 and the part of a length L14 having the calorific value H12. The heating element 53 is constituted of the part of a length L16 having the calorific value H13 and the part of a length L15 having the calorific value H14. The lengths L12, L13, L16 respectively correspond to the materials to be fixed of 1st to 3rd widths. The heating elements 51 and 52 are combined and are respectively independently electrically heated, by which the calorific value distribution in the axial direction can be changed in the case of fixing of, for example, the material to be fixed of the 2nd width.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating roller device used in copying machines, facsimile machines, printers, etc.

0002

[Prior Art] In recent years, heating roller devices used in copying machines, facsimile machines, printers, etc., which are particularly required to be faster, have higher resolution, be smaller and lower in price, are equipped with rod-shaped heaters that extend in the axial direction within a cylindrical portion. A configuration using a cylindrical heating roller provided with lamps is adopted.

FIG. 2 is a sectional view of an example of a fixing device of a conventional electrophotographic apparatus. As disclosed in Japanese Patent Application Laid-Open No. 63-33152, a heating roller has a built-in heater lamp 91 and is rotatably supported by a support member 5 on the outer peripheral surface of a cylindrical heating roller shaft 3 having a surface layer outside the fixing area. 4 rotates while being in pressure contact with the pressure roller 6. The gear 8 is fixed to the heating roller 4 and transmits rotational force. The base 7 firmly supports the bearings of the support member 5 and the pressure roller 6.

FIG. 3 is a sectional view of another example of a conventional fixing device such as an electrophotographic apparatus. Japanese Patent Publication No. 1986-143160
As disclosed in , a conventional heating roller shaft 13 has flanges 10 formed at both ends. Further, the surface layer 4 is applied only to the large diameter portion of the heating roller shaft 13. First and second heater lamps 1 are installed inside the cylinder of the heating roller 13, respectively.
1 and 12, the second heater lamp 12 has a shorter filament than the filament of the first heater lamp 11, and only one of the first and second heater lamps is selected depending on the width of the object to be heated. It was a device that heated up when lit.

[0005]

[Problems to be Solved by the Invention] However, this configuration has many problems as described below.

(1) In the configurations shown in FIGS. 2 and 3, both ends of the heating roller shaft have opening diameters D and D3, which are larger than the heater lamp, and a large air layer exists between them. The air around the heating roller shaft heated by the radiant heat of the heater lamp reaches a high temperature, and flows out through the opening due to convection. On the other hand, low-temperature outside air easily flows in through the large opening with small air resistance, lowering the temperature inside the heating roller, and furthermore, the end surface of the heating roller shaft made of metal with excellent thermal conductivity is exposed at the opening. Therefore, a large amount of heat is dissipated from here to the outside, resulting in an extreme loss of thermal efficiency of the heating roller, and in order to compensate for this, the heater lamp has no choice but to consume a large amount of electric power.

(2) Due to air convection and heat dissipation from both open ends of the heating roller shaft, the temperature distribution in the axial direction of the heating roller becomes non-uniform, and the temperature at both ends is lower than that at the center. In order to maintain the temperature at both ends above a predetermined value, the center becomes abnormally high, causing toner to adhere to the heating roller (high-temperature offset) and thermal deterioration of the heating roller and pressure roller members, causing equipment damage. This resulted in a loss of durability. In addition, a large amount of heat transfers to the support member from the heat roller shaft, which is in contact with the support member and has good thermal conductivity, resulting in high temperatures, which can lead to an increase in frictional torque on the sliding parts and even seizure, which can lead to equipment stoppage, a fatal flaw. Sometimes it happened.

(3) Air convection and heating roller shaft release Heat dissipation from both ends simultaneously heats the base at the periphery, distorts the base due to thermal distortion due to non-uniform temperature of the base, and the heat roller is attached to the base. This deteriorates relative positional accuracy with other members, causing wrinkles, curls, deformation, etc. of the fixing object (for example, paper). In addition, air convection particularly raises the temperature inside the apparatus, which greatly changes the characteristics of the image carrier, paper, and toner, making it impossible to ensure stable printing characteristics. Furthermore, the seal portion 9 of the heater lamp is easily heated to high temperatures by not only high-temperature air but also radiant heat from the large opening of the heating roller shaft, and deterioration of the seal portion is accelerated at high temperatures, which shortens the life of the heater lamp. This was a factor in shortening it. (4) To prevent overheating of the heater lamp, fixing width L1
Since a heat radiation length L4 is required relative to the heating roller width L2, the heater lamp length L3 becomes large, leading to an increase in the size of the device and an increase in the costs of the heater lamp and the heating roller.

(5) Heating light leaks from both open ends of the heating roller shaft, and some of this may enter the image carrier, impairing printing quality, so special light shielding means is required.

(6) In the case of the configuration shown in FIG. 2, a coating of fluorine-containing resin or the like is used on the surface layer of the outer periphery of the heating roller, but since it rotates and slides on a supporting member made of a bearing material, etc., it is wear-resistant. properties and lubrication resistance are required. Depending on the bearing material, the fluorine-containing resin coating often wears out, resulting in poor sliding during high-temperature sliding. Furthermore, because the heating roller rotates eccentrically due to wear, stable contact between the heating roller and the pressure roller cannot be maintained, resulting in unstable fixing. In order to prevent this, the surface layer is applied to the parts other than the sliding parts that fit with the support member. Therefore,
Means for selectively fixing the surface layer to the heating roller shaft (
For example, it is necessary to perform additional work (for example, masking) or only the sliding part with the support member to expose the heating roller shaft and make it slide with the support member, which inevitably increases the number of man-hours and makes it more complicated.

(7) In the case of the configuration shown in FIG. 3, in particular, since the heating roller shaft has a flange portion, the preload from the pressure roller causes stress concentration on the flange portion, causing damage and breakage. In order to prevent this, the flange part and heating roller shaft are made thicker, but on the other hand, the heat capacity increases, which slows down the thermal response characteristics of the heating roller. It took time to upload. In addition, the processing is special and complicated, and it is necessary to adequately manage the manufacturing of the rollers and the maintenance of the equipment.

(8) The heating roller rotates while receiving a preload of several kg to several tens of kg from the pressure roller. Figure 2
In the case of the configuration, the radius of the rotating sliding part is the same as the heating roller radius and is large, so the torque required for rotation is extremely large, requiring a large drive motor with high output, which reduces the cost of the device. This hindered miniaturization.

(9) When fixing objects of different sizes, the temperature distribution of the contact area of the heating roller and the non-contact area of the object is different, and the temperature of the heating roller is not uniform when fixing objects of a small to large width continuously. response was impaired and unnecessary power was wasted. In order to compensate for this, as shown in FIG. 3 (Japanese Unexamined Patent Publication No. 143160/1982), two heater lamps were used and one of them was selectively turned on for heating. However, according to this configuration, since the two heater lamps are inserted into the cylinder of the heating roller shaft, when one heater lamp turns on and heats up, a part of the radiant heat is absorbed by the other heater lamp and the heating roller is heated. It did not contribute to the heat generation of the heat roller, resulting in a loss and lowering the thermal efficiency of the heating roller.

(10) FIG. 4 is a radial cross-sectional view of a fixing device of a conventional electrophotographic apparatus. When the heater lamps 11 and 12 are inserted into the cylinder of the heating roller shaft 13 having the surface layer 2 and the heater lamp 11 is selectively turned on, the radiant heat is directly transmitted downward in the figure to the heating roller shaft 1.
3 becomes a high temperature, but since there is a heater lamp 12 above in the figure, the radiant heat is absorbed by this, and the heating roller shaft 13 becomes low temperature. Arrow 14 represents the temperature in the circumferential direction of the heating roller, and solid line 15 represents the temperature distribution. The temperature distribution is asymmetrical with respect to the center 17 of the heating roller, with the temperature being lower at the top and higher at the bottom. Further, the heating roller rotates in the direction of the arcuate arrow 16. Therefore, thermal strain, deformation, and stress are applied to the heating roller and the supporting member every rotation, resulting in fatigue of the heating roller material, decreased strength of the bonded portion, and uneven wear of the supporting member.

(11) Since two heater lamps are inserted into both open ends of the heating roller shaft, the opening diameter D3 becomes larger and larger, and convection is promoted due to the asymmetric temperature distribution. Therefore, the convective flow of hot air increases, the temperature drop at both ends and the heat transfer to the surrounding area, especially the seal area of the heater lamp, is accelerated, and the radiant heat of one heater lamp is transferred to the seal area of the other heater lamp. Direct heating further deteriorated the seal and shortened its lifespan.

(12) Due to (10) and (11), the thermal efficiency of the heating roller is further reduced, power consumption is increased, the temperature of each part of the device is increased, and it is necessary to provide special light shielding means.

(13) Since the two heater lamps were designed to selectively turn on and heat only one of the first and second heater lamps depending on the width of the object to be heated, the resulting temperature distribution of the heating roller Each type has a unique meaning, and there are only two types, and it has been impossible to control the shape of the axial temperature distribution of the heater lamp.

(14) In the case of a fixing device such as an electrophotographic device, the paper and toner to be fixed are electrically charged, and when the heating roller is electrically charged, the paper is wound around the heating roller by electrostatic force. This caused paper jams, resulting in fire and smoke, which was a major drawback of the device. Furthermore, the toner adsorbs to the heating roller after being heated and melted, causing offset, which deteriorates print quality.

The present invention is intended to solve these problems, and its purpose is to provide a roller that has high thermal efficiency with little loss of heat transfer to the outside, and can control the distribution of heat generation in the axial direction. The purpose of the present invention is to provide a heating roller device with a simple structure, which has a small driving torque and is free from paper wrapping and offset.

[0020]

[Means for Solving the Problems] The heating roller device of the present invention consists of a heating roller and a pressing roller that rotate while being in pressure contact with each other, and has a plurality of portions each having a different amount of heat generated in the axial direction within the cylinder of the heating roller. The present invention is characterized in that heating elements are arranged and at least two of the heating elements can be independently energized.

[0021]

[Operation] Both ends of the heating roller are covered by supporting members. For this reason, (1) the air resistance at both ends increases due to the orifice effect and the labyrinth effect, so convection is inhibited, and there is little outflow of high-temperature air to the outside.

(2) The heat insulating effect of the support member prevents heat loss due to heat transfer from both ends of the heating roller shaft.

(3) Reflecting means disposed at both ends of the heating roller reflect the leaked heat-generating light (electromagnetic waves) from both ends into the interior of the heating roller to heat it.

(4) From (1), (2), and (3),
The temperature drop at the end of the shaft is reduced, and the uniformity of the temperature distribution of the heating roller is improved.

(5) Since there is little heat transfer to the peripheral portions of the heating roller, thermal deformation, thermal deterioration, and characteristics of the image carrier are stabilized at various peripheral portions.

(6) Since the diameter of the second cylindrical surface that performs sliding rotation is small, the torque for driving and rotating the heating roller is small.

(7) The first cylindrical surface on the outer periphery of the heating roller does not perform sliding rotation, and therefore does not require wear resistance or lubrication resistance.

(8) Since the heating roller shaft is composed of a thin pipe with a constant thickness, its heat capacity is small and its thermal response characteristics are fast.

(9) Since the support member has conductivity, the heating roller can be set to a predetermined potential.

(10) Since a plurality of heat generating elements are disposed in one heat generating means, the amount of loss due to radiation light from one being absorbed by the other is extremely small.

(11) Since the amount of current applied to a plurality of heat generating elements having portions with different amounts of heat generated in the axial direction is simultaneously and independently controlled, the shape of the heat distribution in the axial direction of the heat generating means can be freely changed and controlled.

(12) By integrally molding, the drive transmission means can also have the wear resistance, lubrication resistance, and heat resistance that the support member has.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic cross-sectional view of a heating roller device according to the present invention. Components having substantially the same functions and names as those in FIGS. 2, 3, and 4 are given the same numbers, and description thereof will be omitted. A case will be described in which the heating roller device of the present invention is used in a fixing device of an electrophotographic device or the like. The heat generating means 1 has a length that corresponds to or exceeds the length of the object to be fixed, and heat generating elements 30 and 31 consisting of portions with different heat generation amounts are inserted in the axial direction of the long rod-shaped envelope. , and is configured to be sealed by sealing portions 9 at both ends thereof, and an infrared halogen lamp, a ceramic heater, or the like is used, for example. Further, the seal portion 9 has terminals corresponding to the respective heating elements 30 and 31 at its outer end, and can be energized independently or simultaneously. Although not shown, the heat generating means 1 is engaged and fixed to the base 7. heating roller 4
is composed of a heating roller shaft 23 made of, for example, aluminum, stainless steel, ceramics, etc., and a surface layer 22 made of, for example, an elastic layer of synthetic rubber or a coating of fluorine-containing resin, etc. The first cylindrical surface 91 having a diameter D1 is fitted and pivoted by the support member 25, and rotates around the heat generating means 1 together with the support member 25. The support member 25 is made of a bearing material that has wear resistance, lubrication resistance, and excellent heat resistance, and more specifically, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polybutylene terephthalate (PBT). , polyether sulfone (
PES), polyimide (PI), polyamideimide (P
AI), fluorine-based materials such as tetrafluoroethylene (PTFE), polysulfone (PSF), glass-filled phenol (PH
) etc. are processed into a specified shape by compression molding, extrusion, or injection molding, and then coated or oil-impregnated as necessary, or oil-impregnated alloys, graphite, molybdenum disulfide, etc. are used. It is also possible. In addition, the support member 2
A drive transmission means 36, such as a gear or a sprocket, for driving the heating roller 4 is integrally formed on the heating roller 5. Furthermore, by imparting electrical conductivity to such a sliding material, it becomes possible to apply a predetermined potential to the heating roller. Preferably, it is desirable to use a material having a volume resistivity of 101 to 106 Ωcm, more preferably 101 to 102, or less. The support member 25 has a second cylindrical surface 9 having a diameter D2.
2, and is fitted into a hole provided in the base 7 and slidably rotated, thereby pivotally rotating the heating roller 4. It also has an opening 93 having a diameter D larger than the diameter of the heat generating means 1 and less than the diameter of the second cylindrical surface 92, and the heat generating means 1 is inserted into the opening 93. This forms a side surface that connects the first cylindrical surface 91 and the opening 93 and covers the open end of the heating roller 4 . Further, a reflecting means 26 is provided on this side surface. The heat generating means 1 is provided with a reflecting means 27. The reflecting means 26 and 27 reflect electromagnetic waves (from visible light to mid-infrared rays in the case of a halogen lamp) emitted from the heating means 1, for example, metal surfaces, preferably metal mirror surfaces or white surfaces with high reflectance.
Made of materials. Therefore, the electromagnetic wave 32 directed from the heating means 1 toward the end of the heating roller 4 is reflected with high efficiency by the reflecting means 26 and 27, and then selectively radiated to the heating roller shaft 23. On the other hand, the pressing roller 6 includes a pressing roller shaft 33, an elastic member 28 fitted onto the pressing roller shaft 33, and a coating layer 29 fitted onto the elastic member 28.
It is made up of. The pressure means 35 presses the pressure roller 6 against the pressure roller 4. The elastic member 28 is made of a material that allows the pressure roller 6 to contact the pressure roller 4 with a predetermined pressure by the pressure means 35 while maintaining a predetermined nip width, and has sufficient heat resistance, etc., specifically, HTV silicone. Rubber, LT
It is made of heat-resistant elastic material such as V silicone rubber, RTV silicone rubber, fluororubber, and EPDA rubber. Covering layer 29
is made of a material that satisfies wear resistance and heat resistance, such as a fluororesin tube. A pressure means 35 held by the base 7 presses and rotates the pressure roller 6 via a bearing 34 and a pressure roller shaft 33.

In the configuration shown in FIG. 1, both ends of the heating roller 4 are covered by a support member 25, and the support member 25 has an opening diameter D, which is set slightly larger than the heat generating means 1. Preferably, they face each other with a clearance of 2 mm or less. Therefore, the air resistance is large due to the orifice effect in this clearance part, and at the same time, it prevents the high temperature air around the heating roller shaft heated by the radiant heat of the heat generating means 1 from flowing out through the opening part due to convection. Since the inflow of low-temperature outside air is also inhibited, the air temperature inside the heating roller can be maintained at a high temperature. In addition, the reflecting means 26 and the heating roller shaft 2
3 and the reflecting means 27 face each other with a narrow clearance, so the same effect can be obtained even in this clearance portion. Furthermore, in this clearance section, one of the two opposing surfaces is fixed and the other rotates, resulting in a labyrinth effect and a very large air resistance, so that the high temperature air within the heating roller 4 is maintained at an appropriate level. Further, the support member 25 covers the end face of the heating roller shaft made of metal or the like having excellent thermal conductivity via the reflecting means 26. The support member 25 is made of a material with low thermal conductivity such as resin, and its heat insulating effect prevents heat from being dissipated and wasted from the end surface of the heating roller shaft to the outside. Furthermore, the leaked heat generated light from the end of the heating roller, which conventionally was dissipated and wasted outside the periphery, is reflected into the cylinder by the reflecting means 32 and can be used to heat the heating roller. These effects made it possible to significantly improve the thermal efficiency of the heating roller 4. As a result, the heating means 1
It is now possible to maintain the heating roller at a sufficiently high temperature with a small amount of electric power.

Since air convection and heat dissipation from both open ends of the heating roller shaft were prevented, the temperature distribution in the axial direction of the heating roller 4 became substantially uniform. Low temperatures at both ends and abnormally high temperatures at the center are prevented, ensuring stable print quality without toner adhesion to the heating roller (high temperature offset), and no thermal deterioration of the heating roller or pressure roller components. We were able to create a device with excellent durability. Furthermore, since the support member 25 has low thermal conductivity, the temperature of the second cylindrical surface 92 located away from the heating roller is maintained low.
The mechanical reliability of the device has been improved, with no fatal defects such as an increase in frictional torque in sliding parts or even seizures that could cause the device to stop.

It is possible to prevent air convection and heat dissipation from both open ends of the heating roller shaft 23, and to reduce power consumption of the device, there is little heating of the base 7 in the peripheral area, resulting in uneven temperature of the base 7. Since the thermal distortion of the base 7 due to the fixation is reduced, the relative positional accuracy with other members attached to the base 7 is kept constant, and it is possible to perform good fixing without wrinkling, curling, deformation, etc. of the fixing object (for example, paper). It became. Additionally, since the temperature rise inside the device was suppressed to a small level, stable printing characteristics could be ensured without changing the characteristics of the image carrier, paper, or toner. Furthermore, by the support member 25 and the reflection means 26 and 27, the seal portion 9 of the heating means can be kept at a low temperature without being heated not only by high-temperature air convection but also by radiant heat from the large opening of the heating roller shaft 23. Since high-temperature deterioration of the seal portion 9 is suppressed, the life of the heat generating means 1 is kept long and the mechanical reliability of the device is improved.

Since the heat transfer to the seal portion 9 of the heat generating means 1 can be suppressed to a minimum, the heat dissipation length L4 with respect to the fixing width L1 and the heating roller width L2 can be made very small, so that the length L3 of the heat generating means 1 can be made small. This makes it possible to reduce the size and weight of the device, and to reduce the cost of the heat generating means 1 and the heating roller 4.

Highly efficient reflection by the reflecting means 26 and 27, the supporting member 25, the reflecting means 26 and 27, and the heating roller shaft 23
Due to the narrow clearance structure, there is almost no leakage of heating light from both open ends of the heating roller shaft, and no special light shielding means for the image carrier is required.

The surface layer 22 on the outer periphery of the heating roller 4 is fitted and pivotally supported by the heating roller 4 at the support member 25 and the first cylindrical surface 91, but there is no sliding at this part and the surface layer 22 is wear resistant and lubrication resistant. Since properties are not required, it is only necessary to use a material with the best heat-resistant mold release properties. Therefore, high temperature offset could be easily prevented. Further, since there is no sliding wear, there is no wear eccentricity between the support member 25 and the heating roller 4, and the heating roller 4 and the pressing roller 6 are in constant contact, making stable fixing possible. Even if there was an increase in friction torque, the fitting pivot force was improved, further securing strength was ensured, and desirable effects were obtained. Therefore, the surface layer 22 can be applied to the entire surface of the heating roller shaft at once, no special processes such as additional machining or masking are required, and the quality is also stable.

Since the heating roller shaft 23 can be constructed from a pipe having a constant thickness without flanges or the like, it has a simple structure and is inexpensive. Since there are no flanges, no special processing is required, simplifying roller manufacturing management and equipment maintenance management. In addition, there is no stress concentration on the flange, and the heating roller shaft 2
3 can be configured to have a thin wall, so that the heat capacity of the heating roller 4 is small and the thermal response characteristics of the heating roller 4 are fast, and it is possible to shorten the warm-up time at the time of start-up and when continuously fixing objects of different sizes.

The heating roller 4 rotates while receiving a preload load of several kg to several tens of kg from the pressure roller 6. The radius of the second cylindrical surface 92 of the support member 25, which is a rotating and sliding part, is smaller than the radius of the heating roller 4, and the temperature in this part is kept low, so rotation can be performed without increasing the coefficient of friction. The torque required for movement is extremely small, and a small, lightweight drive motor with low output is sufficient to function, making the device lower in price, smaller in size, lighter in weight, and lower in power consumption.

Since the support member 25 is integrally formed with a drive transmission means 36 such as a gear or a sprocket for driving the heating roller 4, there is no need for a dedicated gear or a key, a spline, etc. to firmly connect the gear, and there are no parts required. We were able to reduce the number of points and processing. Further, since the material of the support member 25 is a bearing material having wear resistance, lubrication resistance, and excellent heat resistance, it is also suitable for use in drive transmission.

By imparting conductivity to the support member 25, it becomes possible to apply a predetermined potential to the heating roller. For example, by keeping it at zero level, the heating roller is charged by charging the paper or toner that is the object to be fixed, and by contact friction. Can remove static electricity. Furthermore, by applying a potential with a polarity opposite to that of the paper and toner, the releasability of the paper and toner from the heating roller was significantly improved due to the repulsive force of static electricity. This improves the reliability of the device by preventing paper from wrapping around the heating roller, smoke and fire caused by paper jams, and improves print quality by eliminating offset.

FIG. 5 is a radial cross-sectional view of the heating roller device of the present invention. One heat generating means 1 is constructed so that heat generating elements 30 and 31 consisting of parts having different heat generation amounts are inserted in the axial direction thereof and sealed with seals 9 at both ends thereof, and is composed of a surface layer 22 and a heating roller shaft 23. Because it is inserted into the cylinder of the heating roller 4 and can be energized independently and simultaneously, when one heating element lights up and heats up, only a small amount of its radiant heat is absorbed by the other heating element, and most of the radiant heat is absorbed by the other heating element. contributes to the heat generation of the heating roller 4. Therefore, the temperature of the heating roller 4 is approximately symmetrical with respect to the center 37 of the heating roller 4. The arrow 38 represents the temperature in the circumferential direction of the heating roller 4, and the solid line 39 represents the temperature distribution. The temperature distribution is approximately circular with respect to the center 37 of the heating roller 4. In this way, a heating roller device with low loss, high thermal efficiency, and uniform temperature distribution was realized.

FIG. 6 is a sectional view of another example of the heating roller device of the present invention. Components having substantially the same functions and names as those in FIG. 1 are given the same numbers and their explanations will be omitted. The heating roller 4 is fitted and pivoted by a support member 45 at a first cylindrical surface having a diameter D3 at both ends of its inner periphery, and together with the support member 45, the heat generating means 1
rotate around. The support member 45 has a small diameter, is compact, and has increased rigidity, so that the deformation due to the pressure applied by the pressure means 35 is small, and both rollers stably contact each other. In addition, the cost was reduced because the amount used was small. Furthermore, if the support member 45 is conductive, it can be directly fixed to the pressure roller shaft made of aluminum, stainless steel, etc. by press-fitting or shrink-fitting, so the electrical contact resistance on the first cylindrical surface is very small. did it. The reflecting means 46 is disposed on the end face of the support member 45, and the leaked heat generated from the end of the heating roller, which conventionally was dissipated to the outside, is reflected inside the cylinder by the reflecting means 46, and is used to heat the heating roller. Can be done. Unlike the configuration of FIG. 1, there is no reflecting means 27, but either reflecting means 46, 27 can sufficiently reflect electromagnetic waves.
Encapsulation effect can be obtained. Further, the reflecting means 46 is connected to the supporting member 4.
5 can be made of a material with a high reflectance color such as white or metallic, or by applying a coating with a high reflectance color.

FIG. 7 is a sectional view of still another example of the heating roller device of the present invention. Components having substantially the same functions and names as those in FIGS. 1 and 6 are given the same numbers, and description thereof will be omitted. The support member 45 closes the opening of the heating roller shaft 23 and the reflection means 50
, the narrow clearance formed together with the heat generating means 1 and the heating roller shaft 23 prevents the movement of high temperature air to the outside, and the reflection means 50 reduces the amount of leakage radiant heat from the end, so the seal part 9 of the heat generating means is supported. Even if it is placed inside the member 45 and placed in a position overlapping the heating roller 4, the temperature of the seal portion 9 can be kept within the usable range. Therefore, the length of the heat generating means 1, which was long due to the sealing part and the heat radiation length L4, can be reduced and the distance between both support members can be kept to less than L5, reducing dead space and making the device more compact. became possible.

FIG. 8 is an explanatory diagram of an example of the heating means of the heating roller device of the present invention. A long heat generating means 1 extending in the axial direction is disposed inside the cylinder of the heating roller, and includes a heat generating element 3.
1 and 30 are placed. As shown in FIG. 8(A),
In the heat generating element 30, the light is distributed such that both end portions having lengths L6 and L7 have a higher calorific value per unit length (hereinafter simply referred to as calorific value) than the central portion having length L8. Both ends of the heating element 31 have lengths L9 and L10,
The light is distributed so that the amount of heat generated is lower than that at the central portion, which has a length L11. Further, the length L20 corresponds to a maximum width object to be fixed, and the length L11 corresponds to a narrow object to be fixed. In FIGS. 8(B), (C), and (D), the horizontal axis L indicates the length of the device, and the vertical axis H indicates the amount of heat generated. FIG. 8(B) shows a calorific value distribution 60 of the heating element 30. The amount of heat generated H1 at both ends is slightly higher than the amount of heat generated H2 at the center in order to compensate for heat transfer from both ends of the heating roller. FIG. 8(C) shows a calorific value distribution 61 of the heating element 31. In contrast to the heat generation amount H4 at the central portion through which the narrow object to be fixed passes, the amount of heat generation H3 is set at both ends where the object to be fixed does not pass in order to keep warm. When fixing a narrow object to be fixed, only the heating element 31 is energized to maintain the temperature at both ends at a predetermined value. When fixing a large object to be fixed continuously, only the heating element 30 is energized. As a result, when switching the object to be fixed, since both ends are preheated, the time required to reach the fixing temperature can be shortened. Moreover, FIG. 8(C) shows a calorific value distribution 62 when the heating elements 30 and 31 are energized at the same time. Calorific value distribution 63 when the heating element 31 is energized so that the calorific value H8 is generated at the central part
is shown by the dashed-dotted line in the figure. On the other hand, a broken line in the figure shows a calorific value distribution 64 when the heating element 30 is energized so that the calorific value H9 is generated at the central portion. When both are energized at the same time, the addition of these results in the heat generation distribution 62 shown by the solid line in the figure, which is the heat generation amount H5 at the center, the heat generation amount H6 at both ends, and the heat generation amount H7 at the middle part. It will be done. Even in the non-passing areas at both ends when a narrow object is passing through, the closer you get to both ends, the greater the loss due to heat transfer.To compensate for this, the amount of heat generated at the extreme end H6 is equal to the amount of heat generated at the middle portion H7.
It is desirable to make it larger than . Since the calorific value distribution 62 has a calorific value such that the central portion H5>both end portions H6>middle portion H7, an even better heat generating state can be achieved. Furthermore, by independently changing the amount of electricity applied to the heating elements 30 and 31, the ratio of the amount of heat generated at the central portion H5, both end portions H6, and the intermediate portion H7 could be freely selected. Furthermore, if a temperature sensor is placed in the axial direction of the heat generating means 1 and the amount of current applied to each heat generating element is feedback-controlled,
Furthermore, it is effective. In this way, it has become possible to freely change and control the axial calorific value distribution shape of the heat generating means 1 (in other words, the temperature distribution of the heating roller). Therefore, it has been possible to realize a heat generating means that can freely respond to and control changes in the temperature of the heating roller due to changes in temperature, humidity, and thickness of the object to be fixed.

FIG. 9 is an explanatory diagram of another example of the heating means of the heating roller device of the present invention. 9(A) shows the structure of the heat generating means 1, and FIG. 9(B) shows the calorific value distribution 71 of the heating element 51.
9(C) shows the calorific value distribution 72 of the heating element 52, FIG. 9(D) shows the calorific value distribution 73 of the heating element 53,
9(E) and 9(F) show the calorific value distribution of the heat generating means 1. FIG. As shown in FIG. 9(A), the heating means 1 includes a heating element 51.
, 52, 53 are arranged. The horizontal axis L indicates the length of the device, and the vertical axis H indicates the amount of heat generated. The heating element 51 has a length L12
It emits light with a calorific value H10. The length L12 corresponds to the effective heat generation length for the object to be fixed with the first width. The heating element 52 is composed of a portion with a length L13 having a calorific value H11 and a portion having a length L14 with a calorific value H12, and has a length L1.
3 corresponds to the effective heat generation length for the object to be fixed having the second width. The length L14 corresponds to a residual heat portion through which the second width of the object to be fixed does not pass. The heating element 53 is composed of a length L16 portion with a heat generation amount H13 and a length L15 portion with a heat generation amount H14, and the length L16 corresponds to the effective heat generation length for the object to be fixed having the third width. The length L15 corresponds to a residual heat portion through which the third width of the object to be fixed does not pass. When fixing objects having the first, second, and third widths, each of the heating elements 51, 52, and 53 may be electrically heated independently. When fixing an object, the heat generating elements 51 and 52 and 51 and 53 are used in combination to energize and heat each of them simultaneously and independently, thereby changing the distribution of heat generation in the axial direction. It is now possible to control the temperature distribution fluctuations of the heating roller. heating element 52
, 53 length L17 of the overlapping part of length L13 and L16
corresponds to the effective heat generation length of the object to be fixed having the fourth width. FIG. 9E shows a calorific value distribution 74 when the heating elements 52 and 53 are energized simultaneously. Calorific value distribution 7 when the heating element 52 is energized so that the calorific value H14 is obtained at L13
5 is indicated by a broken line in the figure. On the other hand, a calorific value distribution 76 in the case where the heating element 53 is energized to have a calorific value H15 at L16 is shown by a dashed line in the figure. When both are energized at the same time, they are added, and a heat generation amount distribution 74 shown by a solid line in the figure is obtained, with the heat generation amount H16 at L17 and the heat generation amounts H17 and H24 at both ends. In addition, a heating element 5 is added to this.
1 can be energized simultaneously and independently. Figure 9(F)
shows a calorific value distribution 77 when the heating elements 51, 52, and 53 are energized at the same time. Calorific value distribution 80 when the heating element 51 is energized to have a calorific value H20 at L12
is shown by the two-dot chain line in the figure. Calorific value distribution 7 when the heating element 52 is energized to have a calorific value H18 at L13
8 is indicated by a broken line in the figure. On the other hand, a calorific value distribution 79 in the case where the heating element 53 is energized to have a calorific value H19 at L16 is shown by a dashed line in the figure. When the three are energized at the same time, the addition of these results in the heat generation amount H21 at L17, and the heat generation amount H22 and H23 at both ends, resulting in a heat generation distribution 77 shown by a solid line in the figure. Heating elements 51, 52, 5
By independently changing the amount of electricity applied to 3,
The ratio of the calorific values of H21, H22, and H23 could be freely selected. In addition, temperature sensors 54, 5
5 and 56 in the axial direction of the heat generating means 1 (for example, above the heating roller shaft 23 indicated by the two-dot chain line in FIG. It is even more effective if the amount of current applied to the heating element is controlled by feedback. As a result, a heat generating means can be realized which can be freely controlled in response to changes in the temperature of the heating roller and changes in temperature distribution due to changes in temperature, humidity, and thickness as well as the width of the object to be fixed.

[0049]

[Effects of the Invention] As described above, according to the present invention, (1
) In the configuration of FIG. 1, both ends of the heating roller 4 are connected to the support members 2.
5, the support member 25 has an opening diameter D, which is set slightly larger than the heat generating means 1. Preferably, they face each other with a clearance of 2 mm or less. Therefore, the air resistance is large due to the orifice effect in this clearance, and at the same time, it prevents the high temperature air around the heating roller shaft heated by the radiant heat of the heat generating means 1 from flowing out through the opening due to convection. Since the inflow of low-temperature outside air is also inhibited, the air temperature inside the heating roller can be maintained at a high temperature. Further, since the reflecting means 26, the heating roller shaft 23, and the reflecting means 27 face each other with a narrow clearance, the same effect can be obtained even in this clearance portion. Furthermore, in this clearance part, one of the two opposing surfaces is fixed,
The other roller has a labyrinth effect because it rotates and has a very large air resistance, so the high temperature air inside the heating roller 4 is maintained at an appropriate level. In addition, the end surface of the heating roller shaft made of metal or the like having excellent thermal conductivity is connected to the supporting member 25 through the reflecting means 26.
covers. The support member 25 is made of a material with low thermal conductivity such as resin, and its heat insulating effect prevents heat from being dissipated and wasted from the end surface of the heating roller shaft to the outside. Furthermore, the leaked heat generated light from the end of the heating roller, which conventionally was dissipated and wasted outside the periphery, is reflected into the cylinder by the reflecting means 32 and can be used to heat the heating roller. These effects made it possible to greatly improve the thermal efficiency of the heating roller 4. Moreover, as a result, the heating means 1 can maintain the heating roller at a sufficiently high temperature with a small amount of electric power.

(2) Since air convection and heat dissipation from both open ends of the heating roller shaft were prevented, the heating roller 4
The temperature distribution in the axial direction was approximately uniform. Low temperatures at both ends and abnormally high temperatures at the center are prevented, ensuring stable print quality without toner adhesion to the heating roller (high temperature offset), and no thermal deterioration of the heating roller or pressure roller components. We were able to create a device with excellent durability. Furthermore, support member 2
5 has low thermal conductivity, so the temperature is kept low on the second cylindrical surface 92 located away from the heating roller, resulting in an increase in the frictional torque of the sliding part and even problems such as seizure. There were no fatal flaws that would cause the system to stop, improving the mechanical reliability of the equipment.

(3) Air convection and heating roller shaft 23
It is possible to prevent heat dissipation from both open ends of the device, and to reduce the power consumption of the device, there is less heating of the base 7 in the peripheral area, and thermal distortion of the base 7 due to uneven temperature of the base 7 is reduced. The relative positional accuracy with respect to other members attached thereto is maintained constant, making it possible to perform good fixing without wrinkling, curling, deformation, etc. of the fixing object (for example, paper). Additionally, since the temperature rise inside the device was suppressed to a small level, stable printing characteristics could be ensured without changing the characteristics of the image carrier, paper, or toner. Furthermore, by the support member 25 and the reflection means 26 and 27, the seal portion 9 of the heating means can be kept at a low temperature without being heated not only by high-temperature air convection but also by radiant heat from the large opening of the heating roller shaft 23. Since high-temperature deterioration of the seal portion 9 is suppressed, the life of the heat generating means 1 is kept long and the mechanical reliability of the device is improved.

(4) Since the heat transfer from the heat generating means 1 to the seal portion 9 could be suppressed to a minimum, the fixing width L1
, by making the heat radiation length L4 with respect to the heating roller width L2 very small, the length L3 of the heat generating means 1 becomes small,
The device can be made smaller and lighter, and the cost of the heat generating means 1 and the heating roller 4 can be reduced.

(5) Due to the highly efficient reflection by the reflecting means 26 and 27 and the narrow clearance structure between the supporting member 25, the reflecting means 26 and 27, and the heating roller shaft 23, heating light leaks from both open ends of the heating roller shaft. This eliminates the need for special light shielding means for the image carrier.

(6) Surface layer 22 on the outer periphery of the heating roller 4
is fitted and pivotally supported by the heating roller 4 between the support member 25 and the first cylindrical surface 91, but there is no sliding in this part and wear resistance and lubrication resistance are not required. It is only necessary to use a material with the best mold releasability. Therefore, high temperature offset could be prevented. Further, since there is no sliding wear, there is no wear eccentricity between the support member 25 and the heating roller 4, and the heating roller 4 and the pressing roller 6 are in constant contact, making stable fixing possible. Even if there was an increase in friction torque, the fitting pivot force was improved, further securing strength was ensured, and desirable effects were obtained. Therefore, the surface layer 22 can be applied to the entire surface of the heating roller shaft at once, no special processes such as additional machining or masking are required, and the quality is also stable.

(7) Since the heating roller shaft 23 can be constructed of a pipe of a constant thickness without flanges or the like, it has a simple structure and is inexpensive. Since there are no flanges, no special processing is required, simplifying roller manufacturing management and equipment maintenance management. In addition, since the heating roller shaft 23 can be constructed with a thin wall without stress concentration on the flange portion, the heat capacity is small and the thermal response characteristics of the heating roller 4 are quick. We were able to save time.

(8) The heating roller 4 rotates while receiving a preload load of several kg to several tens of kg from the pressing roller 6. The radius of the second cylindrical surface 92 of the support member 25, which is a rotating and sliding part, is smaller than the radius of the heating roller 4, and the temperature in this part is kept low, so rotation can be performed without increasing the coefficient of friction. The torque required for movement is extremely small, resulting in small output and
Because it functions satisfactorily with a small and lightweight drive motor, the device has been made lower in price, smaller in size, lighter in weight, and lower in power consumption.

(9) The heating roller 4 is attached to the support member 25.
Since the drive transmission means 36, such as gears and sprockets, for driving the gears is integrally molded, there is no need for dedicated gears, keys, splines, etc. to firmly connect the gears, and the number of parts and processing can be reduced. Furthermore, since the material of the support member 25 is a bearing material that has wear resistance, lubrication resistance, and excellent heat resistance, it is also suitable for use in drive transmission.

(10) By imparting conductivity to the support member 25, it becomes possible to apply a predetermined potential to the heating roller, and by keeping it at zero level, for example, it reduces the charging and contact friction of paper and toner that are the objects to be fixed. Electrification of the heating roller due to the heat roller can be removed. Furthermore, by applying a potential with a polarity opposite to that of the paper and toner, the releasability of the paper and toner from the heating roller was significantly improved due to the repulsive force of static electricity. This improves the reliability of the device by preventing paper from wrapping around the heating roller, smoke and fire caused by paper jams, and improves print quality by eliminating offset.

(11) The temperature of the seal portion 9 can be kept within the usable range even if the seal portion 9 of the heating means is placed inside the support member 45 and placed in a position overlapping the heating roller 4. Therefore, the length of the heat generating means 1, which was long due to the sealing part and the heat radiation length L4, can be reduced and the distance between both support members can be kept to less than L5, reducing dead space and making the device more compact. became possible. (12) One heat generating means 1 is constructed so that heat generating elements 30 and 31 consisting of portions with different heat generation amounts are inserted in the axial direction and sealed with the seal portions 9 at both ends, and are enclosed within the cylinder of the heating roller shaft 23. Because they are inserted through each other and can be energized independently and simultaneously, when one heating element lights up and heats up, only a small amount of its radiant heat is absorbed by the other heating element, and most of the radiant heat is generated by the heating roller 4. As a result, a heating roller device with low loss, high thermal efficiency, and uniform temperature distribution was realized.

(13) The amount of current applied to the plurality of heating elements is
By changing each independently, the ratio of the amount of heat generated at each part in the axial direction of the device, such as the center, both ends, and the middle part, could be freely selected. Further, it is even more effective if a temperature sensor is arranged in the axial direction of the heat generating means 1 and the amount of current applied to each heat generating element is feedback-controlled. In this way, it has become possible to freely change and control the axial calorific value distribution shape of the heat generating means 1 (in other words, the temperature distribution of the heating roller). This not only shortens the warm-up time when continuously fixing objects of various widths, but also allows for flexible control in response to changes in the temperature of the heating roller caused by changes in temperature, humidity, and thickness of the object. A heating roller device was realized.

[0061] It has the above effects.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional schematic diagram of a heating roller device of the present invention.

FIG. 2 is a sectional view of an example of a fixing device of a conventional electrophotographic apparatus.

FIG. 3 is a sectional view of another example of a fixing device of a conventional electrophotographic apparatus.

FIG. 4 is a radial cross-sectional view of a fixing device of a conventional electrophotographic apparatus.

FIG. 5 is a radial cross-sectional view of the heating roller device of the present invention.

FIG. 6 is a sectional view of another example of the heating roller device of the present invention.

FIG. 7 is a sectional view of still another example of the heating roller device of the present invention.

FIG. 8 is an explanatory diagram of an example of a heat generating means of the heating roller device of the present invention.

FIG. 9 is an explanatory diagram of another example of the heat generating means of the heating roller device of the present invention.

[Explanation of symbols]

1 Heat generating means 4 Heating roller 6 Pressing roller 7 Base 8 Gear 9 Seal portion 11 12 91 Heater lamp 22 Surface layer 3 13 23 Heating roller shaft 5 25 45 Support member 26 27 46 50 Reflection means 30 3
1 51 52 53 Heating element 33 Pressure roller shaft 34 Bearing 35 Pressure means 36 47 Drive transmission means 54 55 56 Temperature sensor 91 First cylindrical surface 92 Second cylindrical surface 93 Opening

Claims (2)

[Claims] 1. A heating roller device comprising a heating roller and a pressure roller that rotate while being in pressure contact with each other, wherein a plurality of heating elements each having a different amount of heat generation are disposed in the axial direction within a cylinder of the heating roller, and the heating roller comprises: A heating roller device characterized in that at least two of the heating elements can be independently energized. 2. The heating roller device according to claim 1, wherein at least two of the heating elements can be independently and simultaneously energized and controlled independently.