JP2011034983A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive and light-weight fixing device equipped with an electromagnetic induction coil, which causes neither temperature history nor variation in temperature on a heat roller due to a size of fed paper. <P>SOLUTION: The fixing device causes a current to flow in the electromagnetic induction coil arranged in proximity to an endless member having a metal layer formed of a conductor to make the endless member generate heat to heat a member to be fixed. The electromagnetic induction coil is divided into a plurality of coils in a moving direction and a perpendicular direction of the member to be fixed, and includes: a mechanism for preventing a decline in temperature of the endless member corresponding to joints of adjacent coils of the divided coils; or a mechanism for preventing a decline in temperature of the endless member corresponding to both ends of unit coils that are formed of the divided coils. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fixing device using an induction heating method, in particular, to a fixing device that fixes a toner image (image) on a member to be fixed in an image forming apparatus such as an electrostatic copying machine or a laser printer.

  A fixing device incorporated in a copying apparatus using an electrophotographic process heats and melts toner as a developer formed on a member to be fixed, and fixes the toner to the member to be fixed. As a method for heating toner that can be used in the fixing device, a method using radiant heat from a halogen lamp is widely used.

  As a method of using a halogen lamp as a heat source, a pair of rollers is provided so as to be able to provide a predetermined pressure to a member to be fixed and toner, and at least one of the rollers is formed as a hollow cylinder in a cylindrical shape in its internal space. A configuration in which a halogen lamp is arranged is widely used. In this configuration, the roller on which the halogen lamp is disposed forms an action portion (nip) at a position in contact with the other roller, and supplies pressure and heat to the fixing member and the toner guided to the nip. . That is, the fixing member, that is, the sheet, is passed through a fixing point that is a pressure contact portion (nip) between a heating roller provided with a lamp and a pressure roller that rotates following the heating roller to fuse the toner on the sheet. It is worn and fixed on the paper.

  In a fixing device using a halogen lamp, light and heat from the halogen lamp are radiated in the entire circumferential direction of the heating roller to heat the whole. In this case, considering the loss when light is converted into heat and the efficiency when the air in the roller is warmed and the heat is transmitted to the roller, the heat conversion efficiency is 60 to 70%. It is known that the power consumption is low and the warm-up time is long.

  In order to solve the problems peculiar to the heater fixing described above, as shown in Patent Documents 1 and 2, etc., a fixing device using an induction heating technique has been proposed.

  Patent Document 1 discloses a fixing device that heats a metal roller itself by causing a current to flow through an induction coil in which a coil is wound around a core provided along a rotation axis of a fixing (metal) roller, and generating an induced current in the roller. It is disclosed.

  Patent Document 2 has a conductive film containing magnetic field generating means and a pressure roller that is in close contact with the conductive film, and heats the conductive film to be conveyed between the conductive film and the pressure roller. A fixing device that fixes toner on a recording medium to the recording medium is disclosed.

JP-A-9-258586 JP-A-8-76620

  In order to shorten the warm-up time, with a fixing device that employs a thin heat roller or a belt, etc., the temperature history is likely to appear on the heat roller depending on the size of the paper passed, and only the part where the paper has passed is heated. Since energy is consumed, temperature unevenness occurs, and therefore, even in a fixing device to which induction heating is applied, temperature control or a partial heating method is required regardless of the paper size.

  The present invention has been made under the circumstances as described above, and includes an inexpensive and lightweight electromagnetic induction coil that does not cause temperature history or temperature unevenness on the heat roller depending on the size of the paper that has passed through. An object is to provide a fixing device.

  In order to solve the above-described problem, the first aspect of the present invention is to heat a member to be fixed by causing a current to flow through an electromagnetic induction coil disposed in the vicinity of an endless member having a metal layer made of a conductor, thereby heating the endless member. In the fixing device, the electromagnetic induction coil is divided into a plurality in a direction perpendicular to the moving direction of the member to be fixed, and the temperature of the endless member corresponding to the joint of adjacent coils divided into the plurality is prevented. There is provided a fixing device including a mechanism for performing the above operation.

  According to a second aspect of the present invention, there is provided a fixing device in which a current is passed through an electromagnetic induction coil disposed close to an endless member having a metal layer made of a conductor to heat the endless member to heat the member to be fixed. The electromagnetic induction coil is divided into a plurality in a direction perpendicular to the moving direction of the member to be fixed, and includes a mechanism for preventing a temperature drop of the endless member corresponding to both ends of a unit coil composed of the divided coils. A fixing device is provided.

  Hereinafter, various aspects and effects of the present invention will be described.

  1. Since a plurality of air-core coils not having a magnetic core therein are provided, an inexpensive and lightweight coil can be configured.

  2. In a coil having a plurality of divided coils, the joint portion of each coil is inclined by a predetermined angle with respect to the direction perpendicular to the moving direction of the object to be heated, thereby energizing all of the divided coils so that a large size paper is obtained. Even if it is a case where it respond | corresponds to, the big temperature fall of the joint part of a coil can be prevented.

  3. In a fixing device having a magnetic core and having a coil divided in a direction perpendicular to the moving direction of the object to be heated, the end of the coil having the core in each coil is perpendicular to the moving direction of the object to be heated. By tilting at a predetermined angle with respect to a certain direction, even when all the divided coils are energized so as to correspond to a large size paper, a large temperature drop in the joint portion of the coils can be prevented.

  4). In a fixing device including a plurality of coils that are divided in a direction perpendicular to a moving direction of an object to be heated by induction heating, an end shape of the core of each of the coils having a core has at least one of an upper part and a lower part. On the other hand, by projecting at one side and including the electric wire part, it is possible to eliminate the interruption of the magnetic flux generated by the rewinding of the electric wire. Even if it is a case where it respond | corresponds to, the big temperature fall of the joint part of a coil can be prevented.

  5. In the induction heating and fixing apparatus in which a plurality of coils are provided in the direction perpendicular to the conveyance direction of the member to be fixed and these are supported by the same holder, the distance between the pair of coil wires near the joint portion of each coil is set. By widening, the cancellation of magnetic flux at both ends of the coil is reduced, the heat generation efficiency is improved, and the temperature drop at the joint can be reduced.

  6). In an induction heating fixing apparatus that includes a plurality of coils and is supported by the same holder in a direction perpendicular to the conveyance direction of the member to be fixed, the thickness of the magnetic core in the vicinity of the seam portion of each coil is set. By widening, the cancellation of magnetic flux at both ends of the coil is reduced, the heat generation efficiency is improved, and the temperature drop at the joint can be reduced.

  7. In an induction heating fixing apparatus that includes a plurality of coils and is supported by the same holder in a direction perpendicular to the conveyance direction of the member to be fixed, the thickness of the magnetic core in the vicinity of the seam portion of each coil is set. By increasing, the cancellation of magnetic flux at both ends of the coil is reduced, the heat generation efficiency is improved, and the temperature drop at the joint can be reduced.

  8). In an induction heating fixing apparatus provided with a plurality of coils and supported by the same holder in a direction perpendicular to the conveying direction of the fixing member to be heated, particularly when a thin heat roller is used, the heat roller The heat energy is not lost to the bearings at both ends, and the temperature drop can be reduced even immediately after warming up.

  9. In an induction heating and fixing apparatus provided with a plurality of coils and supported by the same holder, by narrowing the distance between the coil near the seam portion of each coil and the object to be heated, It is possible to prevent a temperature drop at the joint portion.

  10. In an induction heating fixing apparatus comprising a plurality of coils having magnetic cores and supporting them with the same holder, by narrowing the gap between the core and the object to be heated in the vicinity of the seam portion of each coil, It is possible to prevent a temperature drop at the joint portion of each divided coil.

  11. By reducing the distance between the coil near the end of the coil at both ends in the longitudinal direction of the divided coil and the object to be heated, it is possible to prevent a temperature drop at both ends immediately after warming up.

  12 By reducing the distance between the core near the ends of the coil at both ends in the longitudinal direction of the coil having a magnetic core divided into a plurality and the object to be heated, it is possible to prevent temperature drop at both ends immediately after warming up. .

  13. A plurality of coils are provided in a direction perpendicular to the conveyance direction of the fixing member to be heated, and each of them is independent or when several of them are connected to form one coil, the same power source of each coil is used. By making the power consumed during continuous operation when operating at the same drive frequency approximately equal to the integrated power when operating alternately, it is possible to control the amount of heat generated by the paper size and further reduce the warm-up time Is possible.

  14 A so-called solenoid coil and a coil wound in a direction perpendicular to the conveyance direction of the heated object in a direction perpendicular to the conveyance direction of the fixing member to be heated are longer than the solenoid coil. By providing the composite coil provided outside the coil and switching the coil according to the size of the paper to be passed, stable heating can be performed without using the divided coils in combination according to the paper size.

  15. In the induction heating and fixing device with a double coil configuration, magnetic flux cancellation is reduced by increasing the distance between opposing coil wires (pairs) at both ends of the coil that are long in the direction perpendicular to the conveying direction of the object to be heated. Thus, it is possible to prevent a temperature drop at both ends immediately after warming up.

  16. In an induction heating fixing device with a double coil configuration, the generated magnetic flux is effectively reduced by bringing the distance between the wire and the object to be heated at both ends of the coil long in the direction perpendicular to the conveying direction of the object to be heated. By acting, it becomes possible to prevent a temperature drop at both ends immediately after warming up.

  17. In the induction heating and fixing device with a double coil configuration, if there are magnetic cores at both ends of the coil that are at least long in the direction perpendicular to the conveyance direction of the object to be heated, the width of the core is widened, and the generated magnetic flux is effective. Thus, it is possible to prevent a temperature drop at both ends immediately after warming up.

  18. In an induction heating fixing device with a double coil configuration, if there are magnetic cores at both ends of the coil that is at least long in the direction perpendicular to the conveyance direction of the object to be heated, the distance between the core and the object to be heated is reduced. By causing the magnetic flux to act effectively, it is possible to prevent a temperature drop at both ends immediately after warming up.

  19. By disposing a coil having two or more parts partitioned by a magnetic material inside and having different heat generating parts, a coil with independent performance can be provided in one device.

  20. By controlling a plurality of coils having different heat generation widths and different outputs with a single microcomputer, it is possible to smoothly carry out individual energization of the divided coils, and to realize cost reduction.

  21. In the coil of the induction heating fixing device configured by combining a plurality of coils, the output can be adjusted to 200 W or less even if the inductances of the plurality of coils are different.

  According to the present invention, since it is configured to include a plurality of air-core coils that do not have a magnetic core therein, it is possible to obtain a fixing device including an inexpensive and lightweight electromagnetic induction coil.

  In addition, by providing a mechanism for preventing a temperature drop of the endless member corresponding to the joint of adjacent coils divided into a plurality of parts, all of the divided coils are energized to cope with a large size paper. However, it is possible to prevent a large temperature drop at the joint portion of the coil.

  Furthermore, by providing a mechanism for preventing the temperature drop of the endless member corresponding to both ends of the unit coil composed of the plurality of divided coils, it is possible to prevent the temperature drop at both end portions immediately after warming up.

The figure which shows the principal part of the fixing device to which the electromagnetic induction coil which concerns on embodiment of this invention is applied. The perspective view which shows the electromagnetic induction coil which consists of an air core coil divided into 3 based on the 1st Embodiment of this invention. The electromagnetic induction coil which made the coil electric wire of the air core coil divided into three into a predetermined angle from the perpendicular | vertical direction with respect to the rotating shaft direction of a heat roller which concerns on the 2nd Embodiment of this invention is shown. Figure. The figure which shows the electromagnetic induction coil which made the magnetic body core of the three-divided coil based on the 3rd Embodiment of this invention incline by the predetermined angle from the perpendicular direction with respect to the rotating shaft direction of a heat roller. . The figure which shows the electromagnetic induction coil made into the shape which protruded at least any one of the upper-lower-end part vicinity of the joint line of the magnetic body based on the 4th Embodiment of this invention. The figure which shows the electromagnetic induction coil which expanded the distance of the coil electric wire (pair) which opposes in the seam vicinity of the air core coil divided into 3 based on the 5th Embodiment of this invention. The figure which shows the electromagnetic induction coil which expanded the width | variety of the magnetic body core in the joint vicinity vicinity of the coil divided into 3 based on the 6th Embodiment of this invention. The figure which shows the electromagnetic induction coil which extended the distance of the coil electric wire (pair) which opposes in the edge part vicinity of the both ends coil of the air core coil divided into 3 based on the 7th Embodiment of this invention. The figure which shows the electromagnetic induction coil which expanded the magnetic body end part width | variety of the both-ends coil of the coil divided into 3 based on the 8th Embodiment of this invention. The figure which shows the electromagnetic induction coil which made the distance of the coil electric wire and the heat roller close | similar to the joint line of the divided | segmented air-core coil based on the 9th Embodiment of this invention. The figure which shows the electromagnetic induction coil which made the distance of the magnetic body core and heat roller close | similar to the joint of the divided | segmented coil based on the 10th Embodiment of this invention. The figure which shows the electromagnetic induction coil which made the distance of the coil electric wire and heat roller close | similar to the edge part coil of the divided | segmented air-core coil based on the 11th Embodiment of this invention. The figure which shows the electromagnetic induction coil which made the distance of the edge part of the magnetic body core and the heat roller of the edge coil of the divided | segmented coil which approached the 10th Embodiment of this invention close. FIG. 20 is a circuit diagram for explaining a fixing device according to a thirteenth embodiment of the present invention. FIG. 20 is a circuit diagram for explaining a fixing device according to a thirteenth embodiment of the present invention. The figure which shows the electromagnetic induction coil which consists of a double coil based on the 14th Embodiment of this invention. The figure which shows the electromagnetic induction coil which consists of a double coil based on the 14th Embodiment of this invention. The figure which shows the electromagnetic induction coil which consists of a double coil based on the 14th Embodiment of this invention. The figure which shows the electromagnetic induction coil which consists of a double coil based on the 14th Embodiment of this invention. The figure which shows the electromagnetic induction coil which has arrange | positioned the coil which has two heat_generation | fever widths in two area | regions divided by the magnetic body core based on 15th Embodiment of this invention. The figure which shows the electromagnetic induction coil which has arrange | positioned the coil which has two heat_generation | fever widths in two area | regions divided by the magnetic body core based on 15th Embodiment of this invention. The figure which shows the other example of the electromagnetic induction coil which concerns on the 4th Embodiment of this invention.

  Hereinafter, various embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a main part of a fixing device to which an electromagnetic induction coil according to various embodiments of the present invention is applied. In FIG. 1, reference numeral 11 denotes a heat roller, and this heat roller 11 is rotated in the direction of the arrow shown by a drive transmission means (not shown) provided at an end portion in the axial direction. The magnetic field generating means 12 arranged in the heat roller 11 generates an alternating magnetic field by a high frequency circuit (not shown), thereby generating an eddy current in the heat roller 11 and generating heat by the Joule heat. .

  The driven roller 13 is pressed against the heat roller 11 by a pressure mechanism (not shown) so as to maintain a predetermined contact width. The driven roller 13 is rotatable, and is driven by the heat roller 11 in the direction of the arrow. Rotate to. The fixing material P passes through the nip between the heat roller 11 and the driven roller 13, and at this time, the image is fixed on the fixing material P by Joule heat.

  In the example shown in FIG. 1, the heat roller 11 is made of iron having an outer diameter of 60 mm and a thickness of 1.0 mm. When such a thin heat roller 11 is used, the amount of heat deprived from the heat roller 11 varies greatly depending on the size of the paper that has been passed through. Therefore, the temperature is set so as to maintain the replenishment amount of heat energy to the portion where the heat has been largely deprived. When the control is performed, a large temperature unevenness (temperature increase in a non-sheet passing portion) is caused in the rotation axis direction of the heat roller.

  FIG. 2 is a perspective view showing the electromagnetic induction coil according to the first embodiment of the present invention. Each of the electromagnetic induction coils shown in FIGS. 2A, 2B, and 2C is an air-core coil that is divided into three parts, a central coil 21a, 22a, 23a, and two end coils 21b, 22b, 23b and 21c, 22c, 23c. Both end coils 21b, 22b, 23b and 21c, 22c, 23c are operated in the same control mode.

  The electromagnetic induction coil shown in FIG. 2 (a) is a so-called solenoid type coil in which both the central coil and the two end coils are wound around the rotation axis of the heat roller, and the electromagnetic induction shown in FIG. 2 (b). The two end coils are solenoid type coils, the central coil is a spiral-shaped so-called planar coil extending in the longitudinal direction, and the electromagnetic induction coil shown in FIG. Both coils are planar coils.

  The electromagnetic induction coils shown in FIGS. 2A, 2B, and 2C are so-called air-core coils that do not have a magnetic core. Since the air-core coil does not have a heavy magnetic core, weight reduction can be achieved, and there is no problem with the Curie point of the magnetic core, so the heat generation efficiency does not decrease.

  However, the air-core coil requires a high current value in order to bring out the necessary coil performance. Therefore, the electric wire forming the coil needs to have a thickness that can withstand this high current, but a thick electric wire cannot be used due to a known skin effect. Therefore, it is necessary to use a litz wire as the electric wire forming the coil. Incidentally, in the present embodiment, 19 heat-resistant enameled wires (polyimide coating) having a thickness of 0.5 mm are twisted.

  In the electromagnetic induction coil according to the present embodiment, the total length of the coil is 320 mm, and the length of the central coil is the most necessary A4 vertical size (210 mm) as a small size paper even when only the central coil is operated. 200 mm or more close to the A4 vertical size is preferable, and in this embodiment, it is set to 230 mm, which is slightly longer than the A4 vertical size.

  As shown in FIG. 2, each coil electric wire is wound around supports 21d, 22d, and 23d of various shapes, and the support needs to have heat resistance, such as polyimide, heat-resistant phenol, A liquid crystal polymer or the like can be used.

  Further, it is possible to fix the coil electric wire by applying a silicone varnish to the surfaces of the supports 21d, 22d, and 23d, thereby suppressing the vibration of the coil.

  As described above, according to the first embodiment, the coil is divided into a plurality of parts, and at least one of the divided coils is an air-core coil, thereby obtaining an inexpensive and lightweight electromagnetic induction coil. It is possible.

  FIG. 3 shows an electromagnetic induction coil according to the second embodiment of the present invention.

  As shown in FIG. 2, the coil can be divided into three parts and energized as necessary to control the temperature. However, when the whole is energized or alternately energized due to the upper limit of power, It has been confirmed that heat generation is reduced at the joint of the coil. As described above, when the heat generation is reduced at the joint, the difference in the fixing rate, the difference in the glossiness of the image surface, the generation of wrinkles due to the difference in the extension of the paper, and the like occur at the joint.

  The electromagnetic induction coil according to the present embodiment prevents a decrease in heat generation at the joint of such a coil.

  That is, as shown in FIG. 3A, the coil is divided into a central coil 31a and two end coils 31b and 31c, and each coil wire is perpendicular to the rotation axis direction of the heat roller. It is wound so as to have an angle inclined by a predetermined angle (30 ° in FIG. 3A). The inclination angle is not particularly limited, but is preferably an angle that eliminates the coil break in the longitudinal direction, and is preferably about 5 ° to 60 °.

  In the electromagnetic induction coil shown in FIG. 3 (a), each turn of the coils 31a, 31b, 31c is wound in an inclined manner. In the electromagnetic induction coil shown in FIG. 3 (b), each of the coils 32a, 32b, 32c is wound. The position of the turn is shifted up and down, and in the electromagnetic induction coil shown in FIG. 3C, the center coil 33a is wound with the position of each turn shifted up and down, and the two end coils 33b and 33c are wound. In the electromagnetic induction coil shown in FIG. 3D, the center coil 34a has a configuration in which the coil length of the upper coil is increased and the coil length of the lower coil is decreased. The two end coils 34b and 34c have a configuration in which the coil length of the upper coil is reduced and the coil length of the lower coil is increased. In the electromagnetic induction coil shown in FIG. And the lower coil are shifted, the both end coil 35b has a smaller coil length of the upper coil, and the lower coil has a larger coil length, and the both end coil 34c has a larger coil length of the upper coil. The coil length is made smaller and larger.

  With such a configuration, the heat generation length of each coil is partially different. Therefore, although there is a temperature drop at the seam portion, the position in the axial direction differs depending on the rotation angle of the heat roller, and the one that has been lowered by about 30 ° C. falls within 10 ° C. It became possible to suppress the decrease in temperature at. As a result, it is possible to suppress the occurrence of wrinkles due to the difference in fixing rate at the seam, the difference in glossiness on the image surface, and the difference in paper extension.

  The electromagnetic induction coil according to the present embodiment is also a so-called air-core coil that does not have a magnetic core, as in the first embodiment. Since the air-core coil does not have a heavy magnetic core, weight reduction can be achieved, and there is no problem with the Curie point of the magnetic core, so the heat generation efficiency does not decrease.

  However, the air-core coil needs a high current value in order to bring out the necessary coil coil performance. Therefore, the electric wire forming the coil needs to have a thickness that can withstand this high current, but a thick electric wire cannot be used due to a known skin effect. Therefore, it is necessary to use a litz wire as the electric wire forming the coil. Incidentally, in the present embodiment, 19 heat-resistant enameled wires (polyimide coating) having a thickness of 0.5 mm are twisted.

  In the electromagnetic induction coil according to the present embodiment, the total length of the coil is 320 mm, and the length of the central coil is the most necessary A4 vertical size (210 mm) as a small size paper even when only the central coil is operated. In addition, the heat escape to the heat roller facing both end coils is 230 mm, which is slightly longer than the A4 vertical size.

  As shown in FIG. 3, each coil wire is wound around supports 31d, 32d, 33d, 34d, and 34e of various shapes, and the support needs to have heat resistance. , Heat-resistant phenol, liquid crystal polymer, and the like can be used.

  Moreover, it is also possible to fix the coil electric wire by applying a silicone varnish to the surfaces of the supports 31d, 32d, 33d, 34d, and 34e, thereby suppressing the vibration of the coil.

  The coil shape is not limited to the shape shown in FIG. 3, and the same effect can be expected if adjacent coils are inclined at the same angle. Moreover, even if not all air-core coils but a type of coil having a magnetic core is included, or even if all the coils are types of coils having a magnetic core, the same effect can be expected. I can do it.

  As described above, according to the second embodiment, the coil is divided into a plurality of parts, and each coil has an angle inclined by a predetermined angle from the vertical direction with respect to the rotation axis direction of the heat roller. Because it is configured, even when all the divided coils are energized to accommodate large-size paper, it is possible to suppress a decrease in heat generation at the joints of the coils, and as a result, the fixing rate at the joints It is possible to suppress the occurrence of wrinkles due to the difference in the gloss, the difference in the glossiness of the image surface, the difference in the elongation of the paper.

  FIG. 4 shows an electromagnetic induction coil according to the third embodiment of the present invention.

  As shown in FIG. 2, the coil can be divided into three parts and energized as necessary to control the temperature. However, when the whole is energized or alternately energized due to the upper limit of power, It has been confirmed that heat generation is reduced at the joint of the coil. As described above, when the heat generation is reduced at the joint, the difference in the fixing rate, the difference in the glossiness of the image surface, the generation of wrinkles due to the difference in the extension of the paper, and the like occur at the joint.

  The electromagnetic induction coil according to the present embodiment prevents a decrease in heat generation at the joint of such a coil.

  That is, as shown in FIG. 4 (a), the coil is divided into a central coil 41a and two end coils 41b and 41c, and the cores 42a, 42b and 42c made of a magnetic material are heated. Is inclined at a predetermined angle from a direction perpendicular to the axial direction of the rotation. The inclination angle is not particularly limited, but is preferably about 5 ° to 60 °.

  With such a configuration, the heat generation length of each coil is partially different. Therefore, although there is a temperature drop at the seam portion, the position in the axial direction differs depending on the rotation angle of the heat roller, and the one that has been lowered by about 30 ° C. falls within 10 ° C. It became possible to suppress the decrease in temperature at. As a result, it is possible to suppress the occurrence of wrinkles due to the difference in fixing rate at the seam, the difference in glossiness on the image surface, and the difference in paper extension.

  Unlike the first and second embodiments, the electromagnetic induction coil according to the present embodiment is a coil having a magnetic core. Each coil is a coil wound in the axial direction of the heat roller having the same shape.

  In the electromagnetic induction coil according to the present embodiment, the total length of the coil is 320 mm, and the length of the central coil 41a is the most necessary A4 vertical size (small size paper) even when only the central coil 41a is operated. 210 mm) and 230 mm, which is slightly longer than the A4 vertical size, because there is heat escape to the heat roller facing both end coils.

  The bobbins of the magnetic cores 42a, 42b, and 42c need to have heat resistance, and polyimide, heat-resistant phenol, liquid crystal polymer, and the like can be used. By applying a silicone-based varnish to the surface of the bobbin, the coil electric wire can be fixed, thereby suppressing the vibration of the coil.

  The coil shape is not limited to the shape shown in FIG. 4A, and the same effect can be expected if the ends of adjacent magnetic cores are inclined at the same angle. For example, the same effect can be obtained by providing an angle as shown in FIG. Alternatively, the shape of FIG. 4A and the shape of FIG. 4B may be combined. Further, the same effect can be expected even if a coil having an air core coil is included instead of a coil having a magnetic core.

  As described above, according to the third embodiment, the coil is divided into a plurality of parts, and the core made of the magnetic material is inclined at a predetermined angle from the direction perpendicular to the axial direction of the heat roller rotation. Therefore, even when energizing all of the divided coils in order to handle large-size paper, it is possible to suppress a decrease in heat generation at the joints of the coils. Further, it is possible to suppress the occurrence of wrinkles due to the difference in the fixing rate at the joint, the difference in the glossiness of the image surface, and the difference in the extension of the paper.

  FIG. 5 shows an electromagnetic induction coil according to a fourth embodiment of the present invention.

  As shown in FIG. 2, the coil can be divided into three parts and energized as necessary to control the temperature. However, when the whole is energized or alternately energized due to the upper limit of power, It has been confirmed that heat generation is reduced at the joint of the coil. As described above, when the heat generation is reduced at the joint, the difference in the fixing rate, the difference in the glossiness of the image surface, the generation of wrinkles due to the difference in the extension of the paper, and the like occur at the joint.

  The electromagnetic induction coil according to the present embodiment prevents a decrease in heat generation at the joint of such a coil.

  That is, as shown in FIG. 5, the coil is divided into a central coil 51a and two two-end coils 51b and 51c, and the cores 52a to 56c made of a magnetic material are at least one of the upper and lower ends. The shape is such that it protrudes at either side and accommodates the coil wire inside. By making the shape of the end portion of the core in this way, the magnetic flux from the coil comes out of the coil end portion slightly toward the heat roller as compared with the case where it is not projected. As a result, the portion with low magnetic flux density at the end of each coil is reduced, and the decrease in heat generation is suppressed.

  Although the length which the edge part of a core protrudes is not specifically limited, About 2-10 mm is preferable.

  In the electromagnetic induction coil shown in FIG. 5A, the upper and lower ends of the cores 52a, 52b, 52c protrude, and in the electromagnetic induction coil shown in FIG. 5B, only the upper and lower ends of the central core 53a protrude. In the electromagnetic induction coil shown in FIG. 5C, the lower end of only the central core 54a protrudes, and in the electromagnetic induction coil shown in FIG. 5D, the lower end of only the central core 54a, The upper end portions of the cores 55b and 55c at both ends protrude greatly, and in the electromagnetic induction coil shown in FIG. 5E, the lower end portions of only the central core 54a and the upper end portions of the cores 55b and 55c at both ends are small. It is the structure which protrudes. Moreover, it is also possible to set it as a structure as shown to Fig.22 (a)-(c).

  With such a configuration, the temperature that has conventionally been reduced by about 30 ° C. at the joint portion of the coil is reduced to within 10 ° C., and the temperature reduction at the joint portion can be suppressed. As a result, it is possible to suppress the occurrence of wrinkles due to the difference in fixing rate at the seam, the difference in glossiness on the image surface, and the difference in paper extension.

  Note that this effect is more effectively exhibited when the distance from the heat roller at the end of the core is shorter than the shortest distance between adjacent cores.

  Unlike the first and second embodiments, the electromagnetic induction coil according to the present embodiment is a coil having a magnetic core. Each coil is a coil wound in the axial direction of the heat roller having the same shape.

  In the electromagnetic induction coil according to the present embodiment, the total length of the coil is 320 mm, and the length of the central coil is the most necessary A4 vertical size (210 mm) as a small size paper even when only the central coil is operated. In addition, the heat escape to the heat roller facing both end coils is 230 mm, which is slightly longer than the A4 vertical size.

  The bobbin of the magnetic core must have heat resistance, and polyimide, heat-resistant phenol, liquid crystal polymer, or the like can be used. By applying a silicone-based varnish to the surface of the bobbin, the coil electric wire can be fixed, thereby suppressing the vibration of the coil.

  The coil shape is not limited to the shape shown in FIG. 5, and the same effect can be expected as long as the end of the magnetic core protrudes. Further, the same effect can be expected even if a coil having an air core coil is included instead of a coil having a magnetic core.

  FIG. 6 shows an electromagnetic induction coil according to the fifth embodiment of the present invention.

  As shown in FIG. 2, the coil can be divided into three parts and energized as necessary to control the temperature. However, when the whole is energized or alternately energized due to the upper limit of power, It has been confirmed that heat generation is reduced at the joint of the coil. As described above, when the heat generation is reduced at the joint, the difference in the fixing rate, the difference in the glossiness of the image surface, the generation of wrinkles due to the difference in the extension of the paper, and the like occur at the joint.

  The electromagnetic induction coil according to the present embodiment prevents a decrease in heat generation at the joint of such a coil.

  That is, as shown in FIGS. 6 (a) and 6 (b), the coil forming method and the outer shape are not changed, and the configuration of the winding is increased in the distance between the opposing coil wires (pairs) in the vicinity of the end. It is said. This prevents a decrease in the generation of magnetic flux at the joints of the coils and promotes heat generation at both ends of each divided coil.

  In the electromagnetic induction coil shown in FIG. 6 (a), the distance between the opposing wires in the adjacent portions of the ends of the coils 61a, 61b, 61c is widened. In the electromagnetic induction coil shown in FIG. 6 (b), The space | interval of the electric wire which opposes in the edge part only of the center coil 61a is made wide.

  Although the space | interval which the electric wire which opposes in a coil edge part was expanded is not specifically limited, About 1.1 to 2 times the space | interval of the electric wire which opposes the longitudinal direction center part of a coil is preferable.

  In the present embodiment, the distance between the opposing wires at both ends of the 20 mm long coil is increased by 5 mm, thereby enabling the temperature on the conductor corresponding to the joint of the coil to be raised by 10 ° C. or more. Yes.

  With such a configuration, it is possible to suppress a decrease in temperature at the joint portion. As a result, it is possible to suppress the occurrence of wrinkles due to the difference in fixing rate at the seam, the difference in glossiness on the image surface, and the difference in paper extension.

  The electromagnetic induction coil according to the present embodiment is also a so-called air-core coil that does not have a magnetic core, as in the first embodiment. Since the air-core coil does not have a heavy magnetic core, weight reduction can be achieved, and there is no problem with the Curie point of the magnetic core, so the heat generation efficiency does not decrease.

  However, the air-core coil requires a high current value in order to bring out the necessary coil coil performance. Thus, the electric wire forming the coil needs to have a thickness that can withstand this high current, but because of the known skin effect, a thick electric wire cannot be used. Therefore, it is necessary to use a litz wire as the electric wire forming the coil. Incidentally, in the present embodiment, 19 heat-resistant enamel wires (polyimide coating) having a thickness of 0.5 mm are twisted.

  In the electromagnetic induction coil according to the present embodiment, the total length of the coil is 320 mm, and the length of the central coil is the most necessary A4 vertical size (210 mm) as a small size paper even when only the central coil is operated. In addition, the heat escape to the heat roller facing both end coils is 230 mm, which is slightly longer than the A4 vertical size.

  As shown in FIG. 6, each coil wire is wound around supports 61d and 62d. The support needs to have heat resistance, and polyimide, heat-resistant phenol, liquid crystal polymer, or the like is used. I can do it.

  Further, it is possible to fix the coil electric wire by applying a silicone varnish to the surfaces of the supports 61d and 62d, thereby suppressing the vibration of the coil.

  The coil shape is not limited to the shape shown in FIG. 6, and the same effect can be expected as long as the distance between the opposing electric wires at the coil end portion is widened. Moreover, even if not all air-core coils but a type of coil having a magnetic core is included, the same effect can be expected.

  As described above, according to the fifth embodiment, since the coil is divided into a plurality of parts and the distance between the opposing coil electric wires (pairs) is increased in the vicinity of the end of the coil, the large size Even when all the divided coils are energized in order to handle the paper of this type, it is possible to suppress a decrease in heat generation at the joints of the coils. As a result, the difference in the fixing rate at the joints and the glossiness of the image surface It is possible to suppress the occurrence of wrinkles due to the difference in the paper length and the difference in the paper extension.

  FIG. 7 shows an electromagnetic induction coil according to a sixth embodiment of the present invention.

  As shown in FIG. 2, the coil can be divided into three parts and energized as necessary to control the temperature. However, when the whole is energized or alternately energized due to the upper limit of power, It has been confirmed that heat generation is reduced at the joint of the coil. As described above, when the heat generation is reduced at the joint, the difference in the fixing rate, the difference in the glossiness of the image surface, the generation of wrinkles due to the difference in the extension of the paper, and the like occur at the joint.

  The electromagnetic induction coil according to the present embodiment prevents a decrease in heat generation at the joint of such a coil.

  That is, as shown in FIG. 7, the width of the magnetic core divided into three parts is changed, thereby changing the shape of the cross section between the end part and the central part, and as a result, the generation of magnetic flux at the joint of the coil is reduced. Heat generation is promoted at both ends of each divided coil.

  In the magnetic core shown in FIG. 7A, the width of both ends of the central core 71a is widened, and the width of the end adjacent to the central core 71a of both cores 71b and 71c is widened. In the magnetic core shown in FIG. 7B, the widths of both ends of the central core 71a are widened, and the widths of the cores 71b and 71c are not particularly changed.

  The widened width at the end of the magnetic core is not particularly limited, but is preferably about 1.1 to 2 times the width of the central portion in the longitudinal direction of the magnetic core.

  In the present embodiment, the width at both end portions of the 30 mm long core is increased by 3 mm, whereby the temperature on the conductor corresponding to the joint of the coil can be increased by 10 ° C. or more.

  With such a configuration, it is possible to suppress a decrease in temperature at the joint portion. As a result, it is possible to suppress the occurrence of wrinkles due to the difference in fixing rate at the seam, the difference in glossiness on the image surface, and the difference in paper extension.

  The electromagnetic induction coil according to the present embodiment is a coil having a magnetic core. In addition, all the coils can use the coil wound in the heat roller axial direction of the same shape.

  In the electromagnetic induction coil according to the present embodiment, the total length of the coil is 320 mm, and the length of the central coil 41a is the most necessary A4 vertical size (small size paper) even when only the central coil 41a is operated. 210 mm) and 230 mm, which is slightly longer than the A4 vertical size, because there is heat escape to the heat roller facing both end coils.

  The bobbins of the magnetic cores 71a, 71b, 71c need to have heat resistance, and polyimide, heat-resistant phenol, liquid crystal polymer, or the like can be used. By applying a silicone-based varnish to the surface of the bobbin, the coil electric wire can be fixed, thereby suppressing the vibration of the coil.

  The shape of the core is not limited to the shape shown in FIG. 7, and the same effect can be expected if the width of the end of the magnetic core is widened. Further, the same effect can be expected even if a coil having an air core coil is included instead of a coil having a magnetic core.

  As described above, according to the sixth embodiment, the coil is divided into a plurality of parts and the width near the end of the core made of the magnetic material is widened. Even when all the divided coils are energized to handle large-size paper, it is possible to suppress a decrease in heat generation at the joints of the coils. It is possible to suppress the occurrence of wrinkles due to the difference in glossiness and the difference in paper extension.

  FIG. 8 shows an electromagnetic induction coil according to a seventh embodiment of the present invention.

  As shown in FIG. 2, the coil can be divided into three parts and energized as necessary to control the temperature. However, in the configuration in which the electric wire is wound in a simple manner, the coil unit includes all the divided coils. As a result, the temperature at both end portions of the heat roller decreases due to heat escape from the open portion of the heat roller or heat escape from a bearing or the like.

  The electromagnetic induction coil according to the present embodiment prevents a decrease in temperature at both ends of such a coil unit.

  That is, as shown in FIGS. 8 (a) and 8 (b), the coil forming method and the outer shape are not changed, and the configuration of the winding is changed to the distance between the opposing coil electric wires (pairs) in the vicinity of the ends of both end coils. It is supposed to be expanded. This prevents a decrease in magnetic flux density at both ends of the coil unit, and promotes heat generation at both ends of the coil unit.

  In the electromagnetic induction coil shown in FIG. 8 (a), the distance between the opposed electric wires at the outer ends in the axial direction of both end coils 81b and 81c is widened without changing the distance between the opposed electric wires of the central coil 81a. The space | interval of the opposing electric wire in the edge part adjacent to 81a is not made wide.

  Further, in the electromagnetic induction coil shown in FIG. 8B, the distance between the opposed electric wires at both ends of the central coil 82a is widened, and the distance between the opposed electric wires of the both end coils 82b and 82c is widened as a whole. .

  Although the space | interval which the electric wire which opposes in a both-ends coil was not specifically limited, about 1.1 to 2 times the space | interval of the electric wire which opposes when it is not spread is preferable.

  In this embodiment, the distance between the opposing wires in the 30 mm long end coil is increased by 3 mm, thereby enabling the temperature on the conductor corresponding to both end portions of the coil unit to be raised by 10 ° C. or more. Yes.

  The electromagnetic induction coil according to the present embodiment is also a so-called air-core coil that does not have a magnetic core, as in the first embodiment. Since the air-core coil does not have a heavy magnetic core, weight reduction can be achieved, and there is no problem with the Curie point of the magnetic core, so the heat generation efficiency does not decrease.

  However, the air-core coil needs a high current value in order to bring out the necessary coil coil performance. Therefore, the electric wire forming the coil needs to have a thickness that can withstand this high current, but a thick electric wire cannot be used due to a known skin effect. Therefore, it is necessary to use a litz wire as the electric wire forming the coil. Incidentally, in the present embodiment, 19 heat-resistant enameled wires (polyimide coating) having a thickness of 0.5 mm are twisted.

  In the electromagnetic induction coil according to the present embodiment, the total length of the coil is 320 mm, and the length of the central coil is the most necessary A4 vertical size (210 mm) as a small size paper even when only the central coil is operated. In addition, the heat escape to the heat roller facing both end coils is 230 mm, which is slightly longer than the A4 vertical size.

  As shown in FIG. 8, each coil wire is wound around supports 81d and 82d, and the support needs to have heat resistance, and polyimide, heat-resistant phenol, liquid crystal polymer, or the like is used. I can do it.

  Further, it is possible to fix the coil electric wire by applying a silicone varnish to the surfaces of the supports 81d and 82d, thereby suppressing the vibration of the coil.

  The coil shape is not limited to the shape shown in FIG. 8, and the same effect can be expected as long as the distance between the opposing electric wires at the ends of the two end coils is widened. Moreover, even if not all air-core coils but a type of coil having a magnetic core is included, the same effect can be expected.

  As described above, according to the seventh embodiment, the coil is divided into a plurality of parts, and the distance between the opposing coil wires (pairs) in the vicinity of the end portions of the both end coils is increased. Even when energizing all of the divided coils in order to accommodate the size paper, it is possible to suppress a decrease in heat generation at the end of the coil unit.

  FIG. 9 shows an electromagnetic induction coil according to the eighth embodiment of the present invention.

  As shown in FIG. 2, the coil can be divided into three parts and energized as necessary to control the temperature. However, in the configuration in which the electric wire is wound in a simple manner, the coil unit includes all the divided coils. As a result, the temperature at both end portions of the heat roller decreases due to heat escape from the open portion of the heat roller or heat escape from a bearing or the like.

  The electromagnetic induction coil according to the present embodiment prevents a decrease in temperature at both ends of such a coil unit.

  That is, as shown in FIG. 9, the width of the magnetic core divided into three parts is changed, thereby changing the shape of the cross section between the end part and the center part. As a result, the generation of magnetic flux at both ends of the coil unit is changed. This prevents the decrease and promotes heat generation at both ends of the coil unit.

  In the magnetic core shown in FIG. 9A, the width of the center core 91a is not changed, and the widths of the end portions of the cores 91b and 91c are widened. The magnetic body shown in FIG. In the core, the width of both end portions of the central core 92a and the width of the end portions of both end cores 92b and 92c are widened. In the magnetic core shown in FIG. 9C, the center core 93a and both end cores 93b are widened. , 93c, both end portions are wider than the center portion.

  The expanded width at the end of the magnetic core is not particularly limited, but is preferably about 1.1 to 2 times the width of the unexpanded portion.

  In the present embodiment, the width at the end of both end cores having a length of 30 mm is increased by 3 mm, thereby enabling the temperature on the conductor corresponding to both end portions of the coil unit to be raised by 10 ° C. or more. .

  The electromagnetic induction coil according to the present embodiment is a coil having a magnetic core. In addition, all the coils can use the coil wound in the heat roller axial direction of the same shape.

  In the electromagnetic induction coil according to the present embodiment, the total length of the coil is 320 mm, and the length of the central coil 41a is the most necessary A4 vertical size (small size paper) even when only the central coil 41a is operated. 210 mm) and 230 mm, which is slightly longer than the A4 vertical size, because there is heat escape to the heat roller facing both end coils.

  The bobbin of the magnetic core must have heat resistance, and polyimide, heat-resistant phenol, liquid crystal polymer, or the like can be used. By applying a silicone-based varnish to the surface of the bobbin, the coil electric wire can be fixed, thereby suppressing the vibration of the coil.

  The shape of the core is not limited to the shape shown in FIG. 9, and the same effect can be expected if the widths of the ends of the magnetic cores at both ends are widened. Further, the same effect can be expected even if a coil having an air core coil is included instead of a coil having a magnetic core.

  As described above, according to the eighth embodiment, the coil is divided into a plurality of parts, and the width in the vicinity of the ends of both end cores made of a magnetic material is increased. Even when energizing all of the divided coils in order to handle large-size paper, it is possible to suppress a decrease in heat generation at the end of the coil unit.

  FIG. 10 shows an electromagnetic induction coil according to the ninth embodiment of the present invention.

  As shown in FIG. 2, the coil can be divided into three parts and energized as necessary to control the temperature. However, when the whole is energized or alternately energized due to the upper limit of power, It has been confirmed that heat generation is reduced at the joint of the coil. As described above, when the heat generation is reduced at the joint, the difference in the fixing rate, the difference in the glossiness of the image surface, the generation of wrinkles due to the difference in the extension of the paper, and the like occur at the joint.

  The electromagnetic induction coil according to the present embodiment prevents a decrease in heat generation at the joint of such a coil.

  That is, as shown in FIGS. 10A and 10B, the electric wire and the heat roller 102 in the vicinity between the divided adjacent coils 101a and 101b and in the vicinity between the coils 103a and 103b. , 104 is approaching. Thereby, the magnetic flux generated in the coil can be effectively applied to the heat roller, and heat generation at both end portions of each divided coil can be promoted.

  In the case of this embodiment, in the vicinity of the joint of the divided coils, the distance between the electric wire and the heat roller is made close to 1 mm over 30 mm, so that the temperature on the conductor corresponding to the joint of the coil can be increased. It was.

  With such a configuration, it is possible to suppress a decrease in temperature at the joint portion. As a result, it is possible to suppress the occurrence of wrinkles due to the difference in fixing rate at the seam, the difference in glossiness on the image surface, and the difference in paper extension.

  The electromagnetic induction coil according to the present embodiment is also a so-called air-core coil that does not have a magnetic core, as in the first embodiment. Since the air-core coil does not have a heavy magnetic core, weight reduction can be achieved, and there is no problem with the Curie point of the magnetic core, so the heat generation efficiency does not decrease.

  However, the air-core coil needs a high current value in order to bring out the necessary coil coil performance. Therefore, the electric wire forming the coil needs to have a thickness that can withstand this high current, but a thick electric wire cannot be used due to a known skin effect. Therefore, it is necessary to use a litz wire as the electric wire forming the coil. Incidentally, in the present embodiment, 19 heat-resistant enameled wires (polyimide coating) having a thickness of 0.5 mm are twisted.

  In the electromagnetic induction coil according to the present embodiment, the total length of the coil is 320 mm, and the length of the central coil is the most necessary A4 vertical size (210 mm) as a small size paper even when only the central coil is operated. In addition, the heat escape to the heat roller facing both end coils is 230 mm, which is slightly longer than the A4 vertical size.

  Each coil electric wire is wound around a support, and the support needs to have heat resistance, and polyimide, heat-resistant phenol, liquid crystal polymer, or the like can be used.

  Further, it is possible to fix the coil electric wire by applying a silicone-based varnish on the surface of the support, thereby suppressing the vibration of the coil.

  Note that the same effect can be expected even if not all air-core coils but a type of coil having a magnetic core is included.

  As described above, according to the ninth embodiment, the coil is divided into a plurality of parts, and the distance between the coil wire near the end of the adjacent coil and the object to be heated is shortened. Even when all the divided coils are energized in order to handle the paper of this type, it is possible to suppress a decrease in heat generation at the joints of the coils. As a result, the difference in the fixing rate at the joints and the glossiness of the image surface It is possible to suppress the occurrence of wrinkles due to the difference in the paper length and the difference in the paper extension.

  FIG. 11 shows an electromagnetic induction coil according to the tenth embodiment of the present invention.

  As shown in FIG. 2, the coil can be divided into three parts and energized as necessary to control the temperature. However, when the whole is energized or alternately energized due to the upper limit of power, It has been confirmed that heat generation is reduced at the joint of the coil. As described above, when the heat generation is reduced at the joint, the difference in the fixing rate, the difference in the glossiness of the image surface, the generation of wrinkles due to the difference in the extension of the paper, and the like occur at the joint.

  The electromagnetic induction coil according to the present embodiment prevents a decrease in heat generation at the joint of such a coil.

  That is, as shown in FIG. 11A, the distance between the heat roller 112, 114 and the portion near the joint between the magnetic cores 111a, 111b of the divided adjacent coils is made closer. Thereby, the magnetic flux generated in the coil can be effectively applied to the heat roller, and heat generation at both end portions of each divided coil can be promoted. In FIG. 11B, the distance between the heat roller 114 and the vicinity of the seam of the magnetic core 113a adjacent to the magnetic core 113b of the end coil is made close without changing the magnetic core 113b of the end coil.

  In the case of this embodiment, in the vicinity of the joint of the divided coils, the distance between the magnetic core and the heat roller is made close to 1 mm over 30 mm, so that the temperature on the conductor corresponding to the joint of the coil can be increased. became.

  With such a configuration, it is possible to suppress a decrease in temperature at the joint portion. As a result, it is possible to suppress the occurrence of wrinkles due to the difference in fixing rate at the seam, the difference in glossiness on the image surface, and the difference in paper extension.

  The electromagnetic induction coil according to the present embodiment is a coil having a magnetic core. In addition, all the coils can use the coil wound in the heat roller axial direction of the same shape.

  In the electromagnetic induction coil according to the present embodiment, the total length of the coil is 320 mm, and the length of the central coil is the most necessary A4 vertical size (210 mm) as a small size paper even when only the central coil is operated. In addition, the heat escape to the heat roller facing both end coils is 230 mm, which is slightly longer than the A4 vertical size.

  The bobbin of the magnetic core must have heat resistance, and polyimide, heat-resistant phenol, liquid crystal polymer, or the like can be used. By applying a silicone-based varnish to the surface of the bobbin, the coil electric wire can be fixed, thereby suppressing the vibration of the coil.

  The shape of the core is not limited to the shape shown in FIG. 11, and the same effect can be expected if the size of the end of the magnetic core in the vicinity of the joint is increased and the distance to the heated body is reduced. I can do it. Further, the same effect can be expected even if a coil having an air core coil is included instead of a coil having a magnetic core.

  As described above, according to the tenth embodiment, the coil is divided into a plurality of parts, and the distance between the end near the seam of the core made of a magnetic material and the object to be heated is reduced. Because it is configured, even when all the divided coils are energized to accommodate large-size paper, it is possible to suppress a decrease in heat generation at the joints of the coils, and as a result, the fixing rate at the joints It is possible to suppress the occurrence of wrinkles due to the difference in the gloss, the difference in the glossiness of the image surface, the difference in the elongation of the paper.

  FIG. 12 shows an electromagnetic induction coil according to the eleventh embodiment of the present invention.

  As shown in FIG. 2, the coil can be divided into three parts and energized as necessary to control the temperature. However, in the configuration in which the electric wire is wound in a simple manner, the coil unit includes all the divided coils. As a result, the temperature at both end portions of the heat roller decreases due to heat escape from the open portion of the heat roller or heat escape from a bearing or the like.

  The electromagnetic induction coil according to the present embodiment prevents a decrease in temperature at both ends of such a coil unit.

  That is, as shown in FIGS. 12 (a) and 12 (b), the coil forming method and the outer shape are not changed, and the configuration of the winding is changed between the coil electric wire and the heat roller 122, It is assumed that the distance to 124 is narrowed. This prevents a decrease in magnetic flux density at both ends of the coil unit, and promotes heat generation at both ends of the coil unit.

  In the present embodiment, the distance between the coil electric wire and the heat roller is made close to 1 mm over the end 30 mm of the both end coils, whereby the temperature on the conductor corresponding to both end portions of the coil unit can be increased by 10 ° C. became.

  The electromagnetic induction coil according to the present embodiment is also a so-called air-core coil that does not have a magnetic core, as in the first embodiment. Since the air-core coil does not have a heavy magnetic core, weight reduction can be achieved, and there is no problem with the Curie point of the magnetic core, so the heat generation efficiency does not decrease.

  However, the air-core coil needs a high current value in order to bring out the necessary coil coil performance. Therefore, the electric wire forming the coil needs to have a thickness that can withstand this high current, but a thick electric wire cannot be used due to a known skin effect. Therefore, it is necessary to use a litz wire as the electric wire forming the coil. Incidentally, in the present embodiment, 19 heat-resistant enameled wires (polyimide coating) having a thickness of 0.5 mm are twisted.

  In the electromagnetic induction coil according to the present embodiment, the total length of the coil is 320 mm, and the length of the central coil is the most necessary A4 vertical size (210 mm) as a small size paper even when only the central coil is operated. In addition, the heat escape to the heat roller facing both end coils is 230 mm, which is slightly longer than the A4 vertical size.

  Each coil electric wire is wound around a support, and the support needs to have heat resistance, and polyimide, heat-resistant phenol, liquid crystal polymer, or the like can be used.

  Further, it is possible to fix the coil electric wire by applying a silicone-based varnish on the surface of the support, thereby suppressing the vibration of the coil.

  Note that the same effect can be expected even if not all air-core coils but a type of coil having a magnetic core is included.

  As described above, according to the eleventh embodiment, the coil is divided into a plurality of parts, and the distance between the coil electric wire and the heated object is reduced in the vicinity of the ends of the both end coils. Even when energizing all of the divided coils in order to cope with the paper, it is possible to suppress a decrease in heat generation at the end of the coil unit.

  FIG. 13 shows an electromagnetic induction coil according to a twelfth embodiment of the present invention.

  As shown in FIG. 2, the coil can be divided into three parts and energized as necessary to control the temperature. However, in the configuration in which the electric wire is wound in a simple manner, the coil unit includes all the divided coils. As a result, the temperature at both end portions of the heat roller decreases due to heat escape from the open portion of the heat roller or heat escape from a bearing or the like.

  The electromagnetic induction coil according to the present embodiment prevents a decrease in temperature at both ends of such a coil unit.

  That is, as shown in FIG. 13, among the divided coils, the distance between the end of the magnetic core 131b of the both end coils and the heat roller 132 is reduced. The adjacent magnetic core 131a is not changed at all. This prevents a decrease in magnetic flux density at both ends of the coil unit, and promotes heat generation at both ends of the coil unit.

  In this embodiment, the distance between the magnetic core 131b and the heat roller 132 is reduced by 1 mm over the end 30 mm of the both end coils, thereby increasing the temperature on the conductor corresponding to both end portions of the coil unit by 10 ° C. Became possible.

  The electromagnetic induction coil according to the present embodiment is a coil having a magnetic core. In addition, all the coils can use the coil wound in the heat roller axial direction of the same shape.

  In the electromagnetic induction coil according to the present embodiment, the total length of the coil is 320 mm, and the length of the central coil is the most necessary A4 vertical size (210 mm) as a small size paper even when only the central coil is operated. In addition, the heat escape to the heat roller facing both end coils is 230 mm, which is slightly longer than the A4 vertical size.

  The bobbin of the magnetic core must have heat resistance, and polyimide, heat-resistant phenol, liquid crystal polymer, or the like can be used. By applying a silicone-based varnish to the surface of the bobbin, the coil electric wire can be fixed, thereby suppressing the vibration of the coil.

  Note that the same effect can be expected even when a coil having an air-core coil is included instead of a coil having a magnetic core.

  As described above, according to the twelfth embodiment, the coil is divided into a plurality of parts, and the distance between the end of the both end core made of a magnetic body and the object to be heated is narrowed. Even when energizing all of the divided coils in order to handle large-size paper, it is possible to suppress a decrease in heat generation at the end of the coil unit.

  14 and 15 are circuit diagrams for explaining a fixing device according to a thirteenth embodiment of the present invention.

  In the present embodiment, as shown in FIG. 14, the electromagnetic induction coil is divided into a central coil 141a and both end coils 141b and 141c, and both end coils 141b and 141c are driven by the same control method. . As a method for driving the coils, a method is considered in which all coils are energized at the time of warm-up, and the other coils are switched by control as necessary. In this case, assuming that all coils are energized simultaneously during warm-up, the output allowed for the fixing device is the sum of the outputs of the central coil 141a and the end coils 141b and 141c.

  For example, assuming that the power allowed for the heating source of the fixing device is 1400 W at the maximum during warm-up when all other device parts are not operating and 900 W at the time of copying, the output of the central coil 141a is 700 W, and both end coils 141b and 141c. The total output is 700W. Normally, the outputs of these coils are varied according to the frequency and are operated mainly at the same timing. However, when a plurality of coils are driven at the same time, a slight difference in frequency causes a beat and noise.

  This can be prevented by the half-bridge method which is forced oscillation, but for example, the number of switching elements increases, which causes an increase in cost. Therefore, if the plurality of coils are respectively driven at the maximum value allowed for the heating device of the fixing device as the central coil 1400W and the two end coils 1400W at the time of warming up, the outputs are 1400W. It remains the same as the heating source, and during copying, it is possible not only to adjust the output by adjusting the frequency, but also to supply the maximum allowable power to the necessary part, as well as to reduce the cost. It is also possible to use a quasi-E class method that is an oscillation.

  At this time, in induction heating, since the range of frequencies that can oscillate is limited, in order to use the output range widely with a plurality of coils, it is necessary to design each coil to obtain the same output at substantially the same frequency. There is.

  Therefore, in this embodiment, the output is set to 700 W to 1400 W at 100 V and the frequency 20 Khz to 40 kHz, and the upper limit of the output is substantially the same, which is the maximum value allowed for the fixing device. Specifically, for example, assuming that the sum of the outputs of the central coil and both end coils is 1400 W at a frequency of about 21 KHz, the frequency is about 39 W at a frequency of about 39 KHz. It is necessary to suppress the coil inductance to a difference of about ± 30.

  At that time, since the center coil and both end coils are driven alternately, it is necessary not to energize at the same time.In addition, when these output differences are large, the voltage drop of the same power line is reduced when driving alternately. Therefore, as shown in FIG. 14B, when alternating energization, the output difference is 200 W or less, and at zero crossing, the energization interval at switching is set to 0 to 20 msec or less, and a plurality of coils are switched. ing.

  Actually, if these controls are performed by a single microcomputer, it is possible to smoothly perform the timing operation at the time of alternate operation, and furthermore, the magnetic characteristics and coil characteristics of the heat roller change due to the temperature change of the heat roller. Thus, even if the oscillation conditions are different, a drive command is smoothly issued, which is simplified as compared with the case of using a plurality of microcomputers, and the cost can be reduced.

  In addition, when alternately energizing each coil, it is possible to include a method of gradually decreasing the frequency without suddenly rising to a predetermined output by changing the frequency, or by supplying a current at a predetermined frequency. It is also possible to take a method of energizing and calculating the power, and then adjusting the output by controlling the frequency. Furthermore, it is also possible to determine the frequency and output based on the previous energization conditions.

  In this embodiment, at the initial stage of alternating energization, the frequency is gradually decreased and the output is gradually increased, so-called soft start is performed for a period of 0.5 seconds or less, and thereafter, the frequency is set based on the previous value. Decide and output, and make corrections while detecting the output. The output is detected by detecting the input voltage and current.

  The fixing device according to the present embodiment includes one power supply unit (a circuit that smoothes alternating current into direct current) and a plurality of oscillation units for the respective coils, and these are controlled by a single microcomputer. Although the oscillation system uses a quasi-E class circuit, the same effect can be obtained by using other known oscillation systems such as a half bridge and full bridge system.

  Further, in the fixing device according to the present embodiment, the temperature of the heat roller generated by each coil and the temperature of the coil itself are detected by a thermistor or the like, and the state of heat generation is monitored, and a thermostat is also provided. .

  Furthermore, the energization time to each coil during the alternate energization can always be switched by the temperature detection means depending on the consumption state and temperature of the heat energy. Drive pattern in advance, and select the pattern by detecting the operating status (for example, warming up, copying, small-size paper copying, ready) with the operating status of the machine body and the temperature detection means described above It is used as.

  Incidentally, as an example of the pattern, there are a combination of 2 seconds for the center coil and 1 second for both end coils, a combination for 2 seconds for the center coil and 0.5 seconds for both ends coils, and the like. Furthermore, a method of detecting the temperature of each coil by the above method and always energizing the lower one is also possible. In these cases, it goes without saying that it is necessary to set an upper limit and a lower limit of the set temperature.

  16 to 19 show an electromagnetic induction coil according to a fourteenth embodiment of the present invention.

  In this embodiment, the electromagnetic induction coil corresponds to the outer coil corresponding to the maximum length of the paper to be heated and the small size paper disposed inside the electromagnetic induction coil, which should originally bring out the main maximum performance. A double structure consisting of the inner coil.

  In the electromagnetic induction coil shown in FIG. 16, the inner coil 162 is a solenoid-wound coil wound around the rotation axis of the heat roller, and the outer coil 161 is used in order to reduce the loss in each coil by setting the magnetic field generation direction to a right angle. Is a winding method (planar type) along the axial direction. A magnetic core 163 is disposed inside the core of the electromagnetic induction coil. In the electromagnetic induction coil shown in FIGS. 17 and 18, both the outer coil 171 and the inner coil 172 are wound along the axial direction. FIG. 17B is a cross-sectional view of the central portion of the electromagnetic induction coil shown in FIG.

  In the case of the electromagnetic induction coil, particularly the outer coil, it is necessary to reinforce heat generation at both ends of the coil as compared to the central portion due to heat radiation from the open portion of the heat roller at both ends and heat lost to the bearings. For this purpose, if both ends of the coil are air cores, as shown in FIG. 19, the distance between the wires at the end of the coil 191 may be increased to reduce the cancellation of the magnetic flux (for example, the minimum portion should be 10 mm). 15mm), or the distance between the wire and the heat roller at the end may be narrowed (3mm to 2mm). When both ends of the coil have a core, the width of the core may be widened at the end (5 mm to 8 mm), or the distance between the end of the core and the heat roller may be brought closer (8 mm is 4 mm). What).

  Note that, by reducing the distance between the core and the heat roller, the temperature drop immediately after the warm-up time can be kept uniform (within 10 ° C.) in the direction of the heat roller rotation axis. Also, this coil is driven by warming up the first coil during warm-up or normal copying. However, when printing on small paper or when both ends generate heat above the set value, the inner coil Will only drive.

  At this time, in induction heating, since the range of frequencies that can oscillate is limited, in order to use the output range widely with a plurality of coils, it is necessary to design each coil to obtain the same output at the same frequency. is there.

  Therefore, in this embodiment, the output is set to 700 W to 1400 W at 100 V and the frequency 20 Khz to 40 kHz, and the upper limit of the output is substantially the same, which is the maximum value allowed for the fixing device. This requires that the plurality of coils are all substantially the same.

  At this time, since the outer coil and the inner coil are driven alternately, it is necessary not to energize at the same time.Furthermore, when these output differences are large, the voltage drop of the same power line is reduced when driving alternately. Therefore, during alternate energization, the output difference is 200 W or less, zero crossing, and the energization interval at the time of switching is set to 0 to 20 msec or less to switch the plurality of coils.

  Actually, if these controls are performed by a single microcomputer, it is possible to smoothly perform the timing operation at the time of alternate operation, and furthermore, the magnetic characteristics and coil characteristics of the heat roller change due to the temperature change of the heat roller. Thus, even if the oscillation conditions are different, a drive command is smoothly issued, which is simplified as compared with the case of using a plurality of microcomputers, and the cost can be reduced.

  Further, in the fixing device according to the present embodiment, the temperature of the heat roller generated by each coil and the temperature of the coil itself are detected by a thermistor or the like, and the state of heat generation is monitored, and a thermostat is also provided. .

  20 and 21 show an electromagnetic induction coil according to a fifteenth embodiment of the present invention.

  The electromagnetic induction coil according to the present embodiment is intended to constitute a coil having a plurality of heat generation widths by preventing leakage of magnetic flux generated by the coil with a magnetic core and combining them.

  That is, as shown in FIG. 20, the electromagnetic induction coil is composed of a long coil 201a and a short coil 201b. The long coil 201a is formed by winding an electric wire around a portion protruding below the core 202, and the short coil 201b. Is configured by winding an electric wire around a portion protruding upward, back to back with the long coil 201a.

  In the example shown in FIG. 21, two E-shaped cores used in a transformer are used back to back, the long coil 211a is configured by winding an electric wire around the lower E-shaped core 212a, and the short coil 211b is An electric wire is wound around the upper E-shaped core 212b.

  The electromagnetic induction coil according to the present embodiment is usually used when the temperature of both end portions rises, such as when starting up the apparatus using a long coil corresponding to the maximum paper width and passing small-size paper. Drive a short coil, opposed to this. Thereby, it becomes possible to prevent the temperature rise of the part of the heat roller corresponding to both ends of the coil.

  DESCRIPTION OF SYMBOLS 11 ... Heat roller, 12 ... Magnetic field generation means, 13 ... Driven roller, 21a, 22a, 23a, 31a, 32a, 33a, 35a, 35a, 41a ... Central coil, 21b, 22b, 23b , 21c, 22c, 23c, 31b, 32b, 33b, 31c, 32c, 33c, 34b, 34c, 35b, 35c, 41b, 41c ... Coil at both ends, 21d, 22d, 23d ... Support, 42a, 42b , 42c... Magnetic body core.

Claims (2)

In a fixing device that heats a member to be fixed by causing a current to flow through an electromagnetic induction coil that is disposed in proximity to an endless member having a metal layer made of a conductor to heat the endless member,
The electromagnetic induction coil is divided into a plurality in a direction perpendicular to the moving direction of the member to be fixed, and includes a mechanism for preventing a temperature drop of the endless member corresponding to the joint of adjacent coils divided into the plurality. A fixing device. In a fixing device that heats a member to be fixed by causing a current to flow through an electromagnetic induction coil that is disposed in proximity to an endless member having a metal layer made of a conductor to heat the endless member,
The electromagnetic induction coil is divided into a plurality in a direction perpendicular to the moving direction of the member to be fixed, and includes a mechanism for preventing a temperature drop of the endless member corresponding to both ends of a unit coil composed of the divided coils. A fixing device characterized by that.

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