JP2007240606A - Image heating device and heating body used for same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image heating device and a heating body used for the same by which temperature rise in an area through which a recording material does not passes is mitigated and throughput of the recording material is raised. <P>SOLUTION: This image heating device has a heating body 100 having a substrate 101, first and second heating bodies 12 provided on the substrate and heats the recording material P which carries an image by heat from the heating body. The first heating body is provided in a first area from one edge to a predetermined position of the substrate. The second heating body is provided in a second area from the other edge to a predetermined position of the substrate. The first and second heating bodies are approximately line symmetry to a virtual line Y at the center of the recording material conveyance direction X. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image heating apparatus suitable for use as a heating and fixing apparatus mounted on an electrophotographic image forming apparatus and a heating body used in the apparatus.

  As an image heating device (fixing device) mounted on an electrophotographic printer or copying machine, a heater having a heating element on a ceramic substrate, a flexible member that moves while contacting the heater, and flexibility Some have a heater and a pressure roller that forms a nip portion via a member. Patent Documents 1 and 2 describe this type of fixing device. The recording material carrying the unfixed toner image is heated while being nipped and conveyed by the nip portion of the fixing device, whereby the image on the recording material is heated and fixed on the recording material. This fixing device has an advantage that the time required to start energization of the heater and to raise the temperature to a fixable temperature is short. Therefore, a printer equipped with this fixing device can shorten the time (FPOT: first printout time) after the printer command is input until the first image is output. This type of fixing device also has an advantage that power consumption during standby for waiting for a print command is small.

  By the way, when a small-size recording material is continuously printed at the same print interval as a large-size recording material with a printer equipped with a fixing device using a flexible member, the area where the recording material of the heater does not pass (non-sheet passing area) Is known to increase excessively (so-called non-sheet passing portion temperature increase). If the non-sheet passing area of the heater is excessively heated, the holder and the pressure roller that hold the heater may be damaged by heat.

  Therefore, a printer equipped with the above fixing device has a control to widen the print interval when continuously printing a small size recording material than when continuously printing a large size recording material, and overheats the non-sheet passing area of the heater. Keeping the temperature down.

However, the control to increase the print interval is to reduce the number of output sheets per unit time, so-called throughput, and it is desired to suppress the number of output sheets per unit time to the same level or slightly less than the case of a large size recording material.
JP 2000-173752 A JP 2001-100558 A

  The present invention is a further development of the above prior art. An object of the present invention is to provide an image heating apparatus and a heating body used in the apparatus that can alleviate the temperature rise in a region through which the recording material does not pass and can improve the throughput of the recording material.

A typical configuration of an image heating apparatus according to the present invention includes a heating body having a substrate and first and second heating elements provided on the substrate, and an image is obtained by heat from the heating body. In an image heating apparatus for heating a recording material to be carried,
The first heating element is provided in a first area from one end of the substrate to a predetermined position, and the second heating element is provided from the other end of the substrate to a predetermined position. An image heating apparatus provided in a second area, wherein the first heating element and the second heating element are substantially line symmetric with respect to a virtual line at a center in a recording material conveyance direction. is there.

A representative configuration of the heating body according to the present invention includes a substrate and first and second heating elements provided on the substrate, and by heat from the first and second heating elements, In a heating element used in an image heating apparatus for heating a recording material carrying an image,
The first heating element is provided in a first area from one end of the substrate to a predetermined position, and the second heating element is provided from the other end of the substrate to a predetermined position. A heating element provided in a second area, wherein the first heating element and the second heating element are substantially line symmetric with respect to a virtual line at a center in a short direction of the substrate. It is.

  ADVANTAGE OF THE INVENTION According to this invention, provision of the heating body used for the image heating apparatus which can relieve the temperature rise of the area | region where a recording material does not pass and can improve the throughput of the recording material is realizable.

Hereinafter, the present invention will be described in detail with reference to the drawings.

(1) Example of Image Forming Apparatus FIG. 7 is a schematic configuration diagram of an example of an image forming apparatus in which the image fixing apparatus according to the present invention can be mounted as a heat fixing apparatus. The image forming apparatus of this example is a tandem type color LBP (color laser beam printer) using an electrophotographic system.

  Y, M, C, and Bk are first to fourth image forming stations for forming toner images of the respective colors of yellow component, magenta component, cyan component, and black component. They are arranged in parallel in order.

  The image forming stations Y, M, C, and Bk are drum-type electrophotographic photosensitive members (hereinafter referred to as photosensitive drums) 1a, 1b, 1c, and 1d, and charging rollers 2a, 2b, 2c, and 2d as charging units, respectively. have. Further, laser beam exposure means (hereinafter referred to as a scanner) 3a, 3b, 3c, 3d, developing devices 4a, 4b, 4c, 4d as developing means, cleaning blades 6a, 6b, 6c, 6d as cleaning means, etc. Have.

  In each of the stations Y to Bk, so-called process cartridges Ca and Cb in which the photosensitive drums 1a to 1d, the charging rollers 2a to 2d, the developing devices 4a to 4d, the cleaning blades 6a to 6d, and the like are collected in one container. , Cc, Cd are used. The developing device 4a of the cartridge Ca is filled with yellow (Y) toner. The developing device 4b of the cartridge Cb is filled with magenta (M) toner. The developing device 4c of the cartridge Cc is filled with cyan (C) toner. The developing device 4d of the cartridge Cd is filled with black (Bk) toner.

  Reference numeral 9a denotes an endless electrostatic attraction and conveyance belt as a carrying and conveying member for the recording material P. The transport belt 9a is arranged in the vertical direction across the stations Y to Bk on the photosensitive drum side (printer front side) of the stations Y to Bk. Reference numerals 9b, 9c, 9d, and 9e denote a driving roller, two fixed rollers, and a tension roller, each of which has a conveyor belt 9a suspended and stretched. The conveyor belt 9a is rotationally driven by a driving roller 9b at a peripheral speed corresponding to the rotational peripheral speed of the photosensitive drums 1a to 1d in the illustrated arrow direction (clockwise).

  Reference numerals 5a, 5b, 5c, and 5d denote first to fourth transfer rollers, which are in pressure contact with the photosensitive drums 1a to 1d of the stations Y to Bk, respectively, via the transport belt 9a.

  In each of the stations Y to Bk, the photosensitive drums 1a to 1d are rotationally driven at a predetermined process speed in the direction indicated by the arrow (counterclockwise). Scanning light based on image data from the scanners 3a to 3d exposes the surfaces of the photosensitive drums 1a to 1d uniformly charged by the charging rollers 2a to 2d on the outer peripheral surfaces (front surfaces) of the photosensitive drums 1a to 1d. Thereby, electrostatic latent images corresponding to the image data are formed on the surfaces of the photosensitive drums 1a to 1d. By setting the developing bias applied to the developing rollers of the developing devices 4a to 4d from a bias power source (not shown) to an appropriate value between the charging potential and the latent image (rear-exposure) potential, it is charged to a negative polarity. The toner is selectively attached to the electrostatic latent images on the surfaces of the photosensitive drums 1a to 1d. Thus, the electrostatic latent image is developed with each color toner.

  On the other hand, a recording material (transfer sheet) P is accommodated in a feeding cassette 8a disposed below the image forming apparatus main body. The recording material P is stored in a state in which any one side abuts against a rib or wall as a fixed reference (conveyance reference) provided in the cassette 8a and the other side opposite to the one side abuts against a movable rib. It is. During image formation, the feed roller 8b rotates to feed the uppermost recording material P in the cassette 8a. At this time, the recording material P is fed to the registration roller pair 8c using the rib or the wall as a transport reference (one-side reference transport). The recording material P is temporarily stopped when the leading end abuts against the registration roller pair 8c. After forming a loop, the rotation of the conveying belt 9a and the image writing position are synchronized, and the recording material P is fed to the conveying belt 9c by the roller pair 8c. Go.

  The negative color toner images developed on the surfaces of the photosensitive drums 1a to 1d are charged with positive charges from the transfer rollers 5a to 5d through the conveying belt 9a to the recording material P conveyed by the conveying belt 9a. By being applied to P, it is superimposed and transferred onto the recording material P surface.

  At the stations Y to Bk, the surfaces of the photosensitive drums 1a to 1d after the transfer of the toner image onto the recording material P are subjected to repeated image formation by removing residual deposits such as transfer residual toner by the cleaning blades 6a to 6d.

  The recording material P that has been subjected to the superimposed transfer of the toner image from each of the photosensitive drums 1 a to 1 d and conveyed to the upper end of the conveying belt 9 a is separated from the surface of the conveying belt 9 a at the drive roller 9 b, and is fixed to the fixing device (fixing device) 10. Is sent to. After the toner image is heated and fixed in the fixing device 10, the toner image is discharged to the discharge tray 14 by the discharge roller 13.

  The above is the operation of the apparatus in the single-sided printing mode. In the double-sided printing mode, the recording material P is conveyed by the discharge roller 13 until the rear end of the recording material P passes through the discharge double-side guide 15. After that, the recording material P is guided to the conveyance path on both sides by reversing the discharge roller 13. Specifically, the rear end of the recording material P is conveyed along the upper surface of the discharge duplex guide 15 by the reverse rotation of the discharge roller 13. The recording material P is further conveyed along guide ribs 11 a provided at the lower part of the ventilation duct 11 and guide guides 12 a provided at the lower part of the operation panel 12, and sent to the double-sided roller 14. Further, the recording material P passes through the downstream duplex rollers 16 and 17 and is then conveyed along the U-turn guide 18. The roller pair 8 c synchronizes the rotation of the conveying belt 9 a and the image writing position to the conveying belt 9 c. It will be fed. Subsequent operations are the same as those in the single-sided printing mode.

(2) Fixing device 10
FIG. 8 is a schematic configuration model diagram of the fixing device 10 in this embodiment. The fixing device 10 of this example is a fixing sleeve heating method and a pressing rotary member driving method (tensionless type).

1) Overall Configuration of Apparatus 10 Reference numeral 20 denotes a fixing sleeve (first fixing member) as a heating member in contact with the image surface of the recording material. The fixing sleeve 20 is a cylindrical (endless sleeve) member in which an elastic layer is provided on a sleeve member. FIG. 10 is a model diagram of the layer structure of the fixing sleeve 20. The sleeve 20 has, for example, an endless belt in which SUS is formed in a cylindrical shape with a thickness of about 50 μm as a base layer 20a, and a silicone rubber layer with a thickness of about 300 μm is formed on the outer peripheral surface as an elastic layer 20b by a ring coating method. The elastic layer 20b is covered with a PFA resin tube having a thickness of about 30 μm as the release layer 20c. For the silicone rubber layer, it is desirable from the viewpoint of temperature rise to use a material having as high a thermal conductivity as possible and to reduce the heat capacity of the sleeve 20. In this embodiment, the material having a thermal conductivity of about 1.0 × 10 ⁻³ cal / sec · cm · K and a silicone rubber having a high thermal conductivity were used. By providing the fluororesin layer on the surface of the sleeve 20, the release property of the surface can be improved, and the offset phenomenon that occurs when the toner once adheres to the surface of the sleeve 20 and moves to the recording material again can be prevented. In addition, by using a PFA tube as the fluororesin layer on the surface of the sleeve 20, a uniform fluororesin layer can be formed more easily.

  An elastic pressure roller (second fixing member) 22 as a pressure member forms the sleeve 20 and the nip portion (fixing nip portion, heating nip portion) N. This pressure roller 22 is formed by forming a silicone rubber layer 22b having a thickness of about 3 mm as an elastic layer 22b on a stainless steel core 22a by injection molding, and a PFA resin tube having a thickness of about 70 μm as a release layer 22c thereon. Covered.

  Reference numeral 100 denotes a fixing heater as a heating body. The heater 100 is a backside heating type ceramic heater as will be described later in section 3). Reference numeral 17 denotes a sleeve guide having heat resistance and rigidity having a substantially semicircular arc shape in cross section. The heater 100 is disposed on the lower surface of the sleeve guide 17 along the length of the holder (direction perpendicular to the rotation direction of the fixing sleeve). The sleeve 20 is loosely fitted on the sleeve guide 17. The sleeve guide 17 is formed of a liquid crystal polymer resin having high heat resistance, plays a role of holding the heater 100 and guiding the fixing sleeve 20.

  The pressure roller 22 is disposed such that both ends of the cored bar 22a are rotatably supported by bearings between side plates (not shown) of the apparatus frame 24 on the back side and the front side. On the upper side of the pressure roller 22, the heating assembly including the heater 100, the sleeve guide 17, the sleeve 20, and the like is arranged in parallel with the pressure roller 22 with the heater 100 facing downward. Then, both end portions of the sleeve guide 17 are urged in the axial direction of the pressure roller 22 with a force of one side 98N (10 kgf) and a total pressure 196N (20 kgf) by a pressure mechanism (not shown). As a result, the downward surface of the heater 100 is brought into pressure contact with the elastic layer of the pressure roller 22 through the sleeve 20 with a predetermined pressing force against the elasticity of the elastic layer, and a predetermined width required for heat fixing (fixing sleeve rotation) A nip portion N having a dimension in the direction) is formed. The pressurization mechanism has a pressure release mechanism, and is configured to release the pressurization and remove the recording material P at the time of jam processing or the like.

  Reference numerals 18 and 19 denote two thermistors, ie, a main thermistor and a sub-thermistor as first and second temperature detecting means. FIG. 9 is a schematic perspective view showing the positional relationship among the fixing sleeve 20, the heater 100, the main thermistor 18, and the sub-thermistor 19.

  The main thermistor 18 is disposed in elastic contact with the inner surface of the fixing sleeve 20 (near the longitudinal end of the fixing sleeve 20). This thermistor 18 has a thermistor element 18b attached to the tip of a stainless steel arm 18a fixedly supported by a sleeve guide 17. Then, the temperature of the inner surface of the sleeve 20 is detected by the thermistor element 18 b that is in contact with the inner surface of the fixing sleeve 20 above the sleeve guide 17.

  The sub-thermistor 19 is disposed in contact with the back surface of the heater 100 that is a heat source, and detects the temperature of the back surface of the heater 100. The location of the thermistors 18 and 19 will be described in detail in the next section 3).

  The thermistors 18 and 19 are connected to a control circuit (CPU) 27 (FIG. 8) as control means of the image forming apparatus. The control circuit 27 determines the temperature control content of the fixing device 10 based on the outputs of the thermistors 18 and 19, and controls the energization of the heater 100 by the heater drive circuit 28.

  In FIG. 8, reference numerals 23 and 26 denote an entrance guide and a fixing paper discharge roller assembled to the apparatus frame 24, respectively. The entrance guide 23 plays a role of guiding the recording material P so that the recording material P separated from the surface of the conveyance belt 9a in the driving roller 9b portion is accurately guided to the nip portion N.

  Each of the members 20, 22, 23, 26, 100 is an elongated member in the direction perpendicular to the recording material conveyance direction X on the surface of the recording material P.

2) Description of fixing operation The pressure roller 22 is rotated by the driving means M in the counterclockwise direction indicated by the arrow at a predetermined peripheral speed. A rotational force acts on the cylindrical sleeve 20 by the pressure friction force at the nip portion N between the outer surface of the pressure roller 22 and the sleeve 20 due to the rotation of the pressure roller 22. Due to the rotational force, the sleeve 20 is rotated in the clockwise direction indicated by the arrow around the outer periphery of the sleeve guide 17 while the inner surface of the sleeve 20 is in close contact with the downward surface of the heater 100 and slides. In the state where the heater 100 is energized and the heater 100 is heated up to a predetermined fixing temperature (target temperature) and the temperature is adjusted, the recording material P carrying the unfixed toner image t in the nip portion N is in the entrance guide 23. Will be introduced along the way. The recording material P introduced into the nip portion N is closely conveyed to the outer surface of the sleeve 20 with the toner image carrying surface side held between the nip portion N and the sleeve 20. In this nipping and conveying process, the heat of the heater 100 is applied to the recording material P through the sleeve 20, and the unfixed toner image t on the recording material P is heated and pressurized on the recording material P to be melted and fixed. The recording material P that has passed through the nip N is separated from the sleeve 20 by the curvature, and is discharged by the fixing discharge roller 26.

3) Description of the heater 100 FIG. 1 is a diagram illustrating an example of the heater 100, and is a view of the heater 100 viewed from the surface on which the heating element pattern is formed. Further, FIG. 1 also shows the positions of the thermistors 18 and 19 in the longitudinal direction of the heater 100. FIG. 2 is a view showing a cross section of the heater 100 in the short direction (width direction) and a relationship between the heater 100, the fixing sleeve, and the pressure roller 22.

  The heater 100 includes a heater substrate 101, the first heating element 1, the second heating element 2, connection electrodes 102 and 103, an insulating coat layer 104, and a sliding surface protective layer 105. .

  The heater substrate 101 is an elongated member in a direction orthogonal to the recording material conveyance direction X. As the heater substrate 101, an insulating ceramic such as alumina or aluminum nitride, or a substrate provided with an insulating layer by means such as applying a glass coat to a metal plate such as SUS can be used. In this example, aluminum nitride was used.

  A first heating element 1 and a second heating element 2 are formed on one side of the heater substrate 101. As the first and second heating elements 1 and 2, a conductive paste applied on the surface of the substrate 101 or a nichrome wire or the like fixed on the surface of the substrate 101 by a known method such as adhesion may be used. Further, the heating elements 1 and 2 do not need to be formed directly on the surface of the substrate 101, and may be, for example, via a glaze layer for preventing diffusion of heat to the substrate 101. Further, the heating elements 1 and 2 may be formed on either the front or back surface of the substrate 101 with respect to the image surface of the recording material P. In the embodiment, a conductive paste containing silver or palladium alloy is uniformly applied to the surface opposite to the image surface of the recording material P on the substrate 101 by a screen printing method, and then fired. Thus, the heating elements 1 and 2 were formed.

  The electrodes 102 and 103 function as contacts for supplying power to the heating elements 1 and 2 from the power supply of the fixing device 10 and the image forming apparatus, respectively, with the amount of power specified by the heater drive circuit 28. In this example, silver paste was formed on both ends of the surface of the substrate 101 by applying a silver paste uniformly by a screen printing method to a film having a thickness of 20 μm, followed by baking, as with the heating elements 1 and 2. .

  The insulating coat layer 104 is formed in a shape that protects the heating elements 1 and 2. The insulating coat layer 104 is formed of an insulating material such as glass or resin, and is provided to ensure the withstand voltage of the heating elements 1 and 2 and the electrodes 102 and 103. In this embodiment, the coating layer made of insulating glass is provided by screen printing with a thickness of 80 μm.

  The sliding surface protective layer 105 in contact with the fixing sleeve 20 is intended to improve the slidability of the fixing sleeve 20 and to protect and prevent scraping of the sliding surface of the heater 100 due to friction with the fixing sleeve 20. It is provided as. For the protective layer 105, for example, a material having heat resistance and low friction such as polyimide (PI) is used. In this embodiment, a varnish-like polyimide precursor having a thickness of 3 to 10 μm is applied and baked to form a polyimide.

  Reference numeral 3 denotes a boundary portion between the first heating element 1 and the second heating element 2.

  The first heating element 1 and the second heating element 2 will be described in more detail.

  In each of the first heating element 1 and the second heating element 2, a heat generation area of heat generated by energization is divided into two in the longitudinal direction of the substrate 101. In the present embodiment, the first heat generating element 1 and the second heat generating element 2 are respectively the first heat generating portions 1a and 2a on the upstream side in the recording material conveyance direction and the second heat generation on the downstream side in the recording material conveyance direction. Part 1b, 2b. The first heat generating element 1 and the second heat generating element 2 are electrically connected in series with the first heat generating parts 1a and 2a and the second heat generating parts 1b and 2b, respectively, through the connecting parts 1c and 2c. Has been. The connecting portions 1c and 2c are formed in parallel with the recording material conveyance direction X.

  In the first heating element 1, the heat generation areas of the first and second heat generating portions 1 a and 1 b correspond to the area where the small size recording material P is conveyed on the one-side conveyance reference along the conveyance reference position O. The length of each heat generating portion 1a, 1b in the longitudinal direction of the substrate 101 is set. The second heat generating element 2 has a large heat generating area of the first and second heat generating portions 2a, 2b outside the heat generating area of the first heat generating element 1 and a large size recording material P on the one-side conveyance reference along the conveyance reference position O. The lengths of the heat generating portions 2a and 2b in the longitudinal direction of the substrate 101 are set so as to correspond to the area where the heat is transferred. As a result, when the small-size recording material P is transported on the one-side transport basis, only the first heating element 1 corresponding to the recording material width in the longitudinal direction of the substrate 101 is used, and the second corresponding to the non-sheet passing region. By not generating heat in the heat generating area of the heating element 2, the temperature rise of the non-sheet passing portion can be mitigated.

  Therefore, it is inevitable to use a heater that uses the same heating element for all the recording materials that can be used in the image forming apparatus. Therefore, it is not necessary to reduce the throughput for the purpose of securing the throughput. Further, the heat generation in the non-sheet passing area of the heater 100 is unnecessary for the function of the fixing device 10 that heats and fixes the unfixed toner image t of the recording material P. For this reason, not generating heat in the heat generating area of the second heating element 2 corresponding to the non-sheet passing area reduces the power used to heat the non-sheet passing area, thereby reducing power consumption. Is done.

  In the first and second heating elements 1 and 2, the first heat generating portions 1 a and 2 a on the upstream side in the recording material conveyance direction are provided at substantially the same position with respect to the recording material conveyance direction X. The second heat generating portions 1b and 2b on the downstream side in the recording material conveyance direction are provided at substantially the same position with respect to the recording material conveyance direction X. In the first heating element 1, the positional relationship between the position of the first heat generating portion 1a upstream in the recording material transport direction and the position of the second heat generating portion 1b downstream in the recording material transport direction is the length of the substrate. It is parallel to the direction and provided at substantially the same position with respect to the recording material conveyance direction X. Further, in the second heat generating element 2, the positional relationship between the position of the first heat generating portion 2a on the upstream side in the recording material transport direction and the position of the second heat generating portion 2b on the downstream side in the recording material transport direction is the longitudinal direction of the substrate. It is parallel to the direction and provided at substantially the same position with respect to the recording material conveyance direction X. As described above, the shape of the heating element is parallel to the longitudinal direction of the substrate, and the upstream heating unit and the downstream with respect to the imaginary line Y shown in the figure, which is the center of the substrate short direction or the recording material conveyance direction. The side heat generating part is line-symmetric.

  By disposing the heat generating portions 1a, 1b, 2a and 2b of the first and second heat generating elements 1 and 2 as described above, the heat generating elements 1 and 2 can move in the recording material conveyance direction X. The heat generation area can be made equal. Thus, no matter which heating element 1 or 2 is used, the time from the toner melting to fixing with the nip pressure does not change. Therefore, there is no difference in image characteristics such as fixability and gloss.

  The electrode 102 has two electrodes 102a and 102b that are individually connected to the heat generating portions 1a and 1b of the first heat generating element 1 at one end in the longitudinal direction on the substrate 101. An AC voltage is applied to the heating element 1 through the electrodes 102a and 102b. The electrode 103 has two electrodes 103a and 103b that are individually connected to the heating portions 2a and 2b of the second heating element 2 at one end in the longitudinal direction on the side different from the electrode 102 on the substrate 101. An AC voltage is applied to the heating element 1 through the electrodes 103a and 103b. Thereby, although the connector for electric power feeding (not shown) is connected to the longitudinal direction both ends of the heater 100, the form which supplies with electricity with respect to the one heat generating body 1 and 2 from one connector can be taken.

  In addition, since the conveyance of the recording material P is based on the one-side conveyance, when the recording material corresponds to two types of recording materials, the large size recording is performed on one side adjacent to the first heating element 1 corresponding to the small size recording material. It is only necessary to provide the second heat generating element 2 corresponding to the material, and the heat generating area may be divided into two places in the longitudinal direction of the substrate 101. Therefore, it is possible to reduce the number of heat generation areas in the longitudinal direction of the substrate 101, and to make the conductive pattern and the heating element pattern simpler. In addition, the wiring to the heating elements 1 and 2 can also be simplified.

  The longitudinal position of the heating element pattern in this embodiment will be described with reference to FIG. The values in parentheses shown indicate the longitudinal position from the conveyance reference position O (0 mm). The illustrated conveyance reference position O is used as a recording material conveyance reference, and recording materials of all sizes are conveyed such that one side in the width direction moves along that position.

  Here, the “predetermined position” described in claims 1 and 7 of the present invention is, for example, the position shown in FIG. The region including the first heating element 1 is defined as the first area, and the second heat generation is generally performed with the boundary line 3 cut at this position in the short direction of the heating body 100, that is, the recording material conveyance direction X. A region including the body 2 is defined as a second area. In this embodiment, the heat generating element 1 for the small size recording material, which is the first heat generating element 1, corresponds to the B5 size (width: 185 mm), and generates heat so that the maximum sheet passing width corresponds to the LTR size (width: 216 mm). The body pattern is set. A position (190.5 mm) from the conveyance reference position O is set as a predetermined position.

  The heating element 1 had a B5 size recording material as a heat generating area from the position of (-3 mm) to the position of (188 mm) so that the conveyance area in the longitudinal direction and the both ends increased by 3 mm. The heating area of the heating element 2 corresponds to an A4 size (210 mm) and an LTR size (216 mm) which is the maximum sheet passing width. An area from the transport reference position O to the position (193 mm) to the position (219 mm) was defined as a heat generation area.

  The main thermistor 18 is disposed within the minimum sheet passing width (minimum sheet passing region), and the recording material P is not affected by the temperature rise of the non-sheet passing portion even when the recording material P having any size is conveyed by the nip portion N. It is configured so that the temperature applied to the can be controlled. For this reason, it may be arranged between the conveyance reference position O and the envelope size which is the minimum sheet passing width, and in this embodiment, it is (49 mm) from the conveyance reference position O so as to be the center of the conveyance area in the longitudinal direction of the minimum size recording material. It was provided in the position.

  Since the sub-thermistor 19 detects the non-sheet passing portion temperature rise, the sub thermistor 19 needs to be arranged in an area within the maximum sheet passing width and outside the minimum sheet passing width. In the present embodiment, the heating element 1 is disposed at a position corresponding to the connection portion 1c which is the end portion on the folded portion side.

In Table 1, in the image forming apparatus provided with the heating body 100 of the present embodiment shown in FIG. 1 and the conventional two types of heating bodies, the temperature rise of the non-sheet passing portion at the time of passing a small size recording material, The result of examining the gloss difference between the printing of the small size recording material and the printing of the large size recording material is shown. Of the two conventional types of heating elements, one is the heating element 900 shown in FIG. 11 which is a single-circuit feeding type, and the other is the multiple-circuit feeding type shown in FIG. This is a heating body 1000. The heating element 1000 shown in FIG. 12 is also configured so that the heat generation area in the longitudinal direction of the heating element for small size recording material corresponds to the B5 size.

  The temperature rise of the non-sheet-passing part when passing through small-size recording materials is 10 sheets of regular envelope paper (width 105mm) continuously under the conditions that the temperature control temperature of the main thermistor 18 is 197 ° C and the process speed is 181mm / sec. When the paper was passed, the sub-thermistor 19 measured the heater back surface temperature that would be the non-paper passing portion. In the heating body 100 and the heating body 1000, a small-size recording material heating element is used. The temperature rise of the non-sheet passing portion of the heating body 900 exceeded 300 ° C., and the sleeve guide 17 was melted at the end portion. Thus, in the heating body 900, it is necessary to reduce the fixing temperature by cooling the member and slowing the process speed by reducing the throughput.

  On the other hand, the temperature increase in the non-sheet passing portion of the heating body 100 and the heating body 1000 was about 240 ° C. This is a temperature rise that does not damage the member, and the heating body 100 and the heating body 1000 can eliminate the need for a throughput reduction.

Next, the difference between the gloss at the time of passing the small size recording material and the gloss at the time of passing the large size recording material was examined. A solid image of yellow, magenta, cyan, and black under the conditions that the temperature control temperature of the main thermistor 18 is 177 ° C. and the process speed is 60 mm / sec, glossy paper with a basis weight of 120 g / m ² in B5 size and LTR size (hp glossy photo & imaging gloss paper).

  The gross value was measured with a probe with an incident angle of 75 ° using a gloss meter (PG-3D) manufactured by Nippon Denshoku Technical Center. In the heating body 100 and the heating body 900, the gloss of the fixed image hardly changed between the envelope width size paper and the LTR size paper.

  However, in the heating body 1000, gloss substantially the same as that of the heating body 100 and the heating body 900 was obtained with the LTR size paper, but the gloss was an image as low as about 30% in the envelope width size.

  As described above, the heating body 100 of the present embodiment can reduce the temperature rise of the non-sheet passing portion and can eliminate the need for throughput reduction, and the image quality of the fixed image can be seen depending on the recording material size as seen in the heating body 1000. It was possible to avoid the problem of damage. From the above, the effect of the present embodiment described above was shown.

  That is, in the heating body 100 of the present embodiment, the first heating element 1 is provided in a first area from one end of the substrate 101 to a predetermined position. The second heating element 2 is provided in a second area from the other end of the substrate 101 to a predetermined position. The first heating element 1 and the second heating element 2 are substantially line symmetric with respect to a virtual line at the center in the recording material conveyance direction.

  Therefore, when the fixing device 10 is mounted on an image forming apparatus that transports a recording material such that one side of the recording material P moves along a fixed reference regardless of the size of the recording material P, a small-sized recording material is transported. Even at times, only the first heating element 1 corresponding to the recording material width is used. That is, by not generating heat in the heat generating area of the second heat generating element 2 corresponding to the non-sheet passing area when the small-size recording material is conveyed, the temperature increase in the non-sheet passing section can be mitigated and the throughput can be secured.

  Furthermore, no matter which heating element 1 or 2 is used, the time from the toner melting to the fixing with the nip pressure does not change, and therefore it is possible to avoid the occurrence of a difference in image characteristics such as fixing properties and gloss. .

  Further, when the heater 100 capable of providing both of these effects is obtained, if the heater 100 is mounted on the fixing device 10 and the image forming apparatus of one-side reference conveyance, in order to correspond to N recording material sizes, the longitudinal direction is required. What is necessary is just to divide the heat generating area into N in the direction. However, in the central reference transport fixing device that transports the recording material by aligning the center of the recording material with the transport width center of the recording material, 2N-1 heating regions are formed in the longitudinal direction in order to correspond to the size of N recording materials. Will be divided. Therefore, the number of divisions of the heat generation area of the heater can be reduced as compared with the central reference conveyance. That is, the heating element pattern of the heater 100 that provides the above-described effect can be realized with a simpler shape in the one-side transfer machine, and therefore can be created at a lower cost.

  As described above, it is possible to provide a fixing device having a simple heater pattern and a heater suitable for an image forming apparatus that performs one-side reference conveyance that can reduce the temperature rise of the non-sheet passing portion.

  Next, another example of the heating body according to the present invention will be described.

  The same members and portions as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The heating body of the present embodiment is different from the heating body 100 described in Embodiment 1 in that the shape of the folded portion of the heating element is appropriately set. Except this point, the second embodiment is the same as the first embodiment.

  The heating body of this embodiment is intended to further improve the image uniformity such as the fixability in the width direction of the recording material and the gloss of the fixed image of the large size recording material as compared with the first embodiment. Therefore, a contrivance is made to increase the uniformity of the amount of heat given to the recording material P between the heating element 1, the heating element 2, and the boundary portion 3 between the heating element 1 and the heating element 2.

  3 and 4 show the heating elements 300 and 400 of the present embodiment, respectively. In the heating elements 300 and 400, the width and thickness of the heating elements 1 and 2 are uniform, and the amount of heat generated from one heating element is uniform.

In the heating element 300 according to the first embodiment of the present embodiment shown in FIG. 3, both the first heating element 1 and the second heating element 2 are heated on the upstream side in the recording material conveying direction, and the recording material. The lengths of the heat generating portions 1b and 2b on the downstream side in the transport direction are different. Further, the heating portions 1a, 2a on the upstream side in the recording material conveyance direction and the connection portions 1c, 2c connecting the heat generation portions 1b, 2b on the downstream side in the recording material conveyance direction are heat generation portions, and the heat generation portions are arranged in the recording material conveyance direction X. On the other hand, it is tilted. Thereby, the gap in the longitudinal direction between the heat generating area of the heat generating element 1 and the heat generating area of the heat generating element 2 can be reduced.
And in the heating body 400 which is the 2nd form of a present Example shown in FIG. 4, the heat generating parts 1a and 1b of the 1st heat generating body 1, the heat generating parts 2a and 2b of the 2nd heat generating body 2, and the heat generating body 1 The following relational expression is established for the boundary 3 between the heating element 2 and the heating element 2. That is, in the recording material conveyance direction X, the length or width l _1a of each of the upstream heat generating portion 1a, the downstream heat generating portion 1b, the upstream heat generating portion 2a, the downstream heat generating portion 2b, and the boundary portion 3 _; For l _1b , l _2a, l _2b , and l ₃ , the following relational expressions were established.

l _1a ≠ l _1b ,
l _2a ≠ l _2b ,
l _1a + l _2a = l _1b + l _2b ,
| L _1a- l _1b | ≧ l ₃
In the heating portions 1a, 1b, 2a, and 2b of the first and second heating elements 1 and 2b, the positions of the end portions on the electrodes 102 and 103 side are the same positions on the upstream side and the downstream side in the recording material conveyance direction X. Is set to Thereby, the heat generating area in the longitudinal direction of the substrate 101 of the heating element 1 and the heat generating area in the longitudinal direction of the substrate 101 of the heating element 2 can be set to have an overlapping area.

  Here, in this embodiment, the heat generation area of the first heating element 1 cannot be included in the first area with the “predetermined position” defined in claims 1 and 7 as a boundary, and the second area is not included. The heat generation area of the second heating element 2 cannot be included. However, since the heating area of the heating element 1 and the first area substantially show the equivalent range, they are included in the scope of the present invention.

  An LTR size recording material (width: 216 mm) was printed as a large size recording material using an image forming apparatus equipped with the fixing device 10 having the heating body 400 of this example. Then, compared with the case where the heating element 100 of Example 1 is used, a fixed image with more uniform image characteristics such as gloss and fixability is obtained in the region of the boundary portion 3 between the heating element 1 and the heating element 2. I was able to.

  As described above, the effect of the present embodiment described above was shown.

  That is, also in the form of the heating elements 300 and 400 of the present embodiment, the first heating element 1 is provided in the first area from one end of the substrate 101 to a predetermined position. The second heating element 2 is provided in a second area from the other end of the substrate 101 to a predetermined position. The first heating element 1 and the second heating element 2 are substantially line symmetric with respect to a virtual line at the center in the recording material conveyance direction. Therefore, the same operations and effects as those of the first embodiment can be obtained.

  Further, the heating elements 300 and 400 of the present embodiment are the heating elements 1a and 2a on the upstream side in the recording material conveyance direction and the heat generation on the downstream side in the recording material conveyance direction with respect to the first heating element 1 and the second heating element 2. The heating portions 1c and 2c connecting the portions 1b and 2b are formed to be inclined with respect to the recording material conveyance direction X. In addition, a part of the heat generation area in the longitudinal direction of the substrate 101 of the first heating element 1 and a part of the heat generation area in the longitudinal direction of the substrate 101 of the second heating element 2 overlap. As a result, it is possible to further improve the image uniformity such as the fixing property and gloss in the recording material width direction of the fixed image of the large size recording material as compared with the heating body 100 of the first embodiment.

  Next, another example of the heating body according to the present invention will be described.

  The same members and portions as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The heating body of the present embodiment is different from the heating bodies 300 and 400 described in Embodiment 2 in that the resistivity of the folded portion of the heating element is appropriately set. Except this point, the second embodiment is the same as the first embodiment.

  In order to further improve the image uniformity as compared with the heating body of the second embodiment, the heating body of the present embodiment has a heating element 1, a heating body 2, and a boundary portion 3 between the heating body 1 and the heating body 2. The device is devised to further increase the uniformity of the amount of heat applied to the recording material P in comparison with the second embodiment.

  Therefore, in this embodiment, the folded portions (heat generating portions 1c and 2c) shown in the second embodiment are inclined with respect to the recording material conveyance direction X, and the heat generating area in the longitudinal direction of the substrate 101 of the heat generating element 1 and the heat generating element 2 The heating elements 1 and 2 are formed so that the heating area in the longitudinal direction of the substrate 101 overlaps. In addition, the partial resistance of the folded portions of the heating elements 1 and 2 is increased to increase the amount of heat generation.

  5 and 6 show heating bodies 500 and 600 of the present embodiment, respectively.

In the heating elements 500 and 600, the thicknesses of the heating elements 1 and 2 are uniform, and the partial resistance of the heating elements 1 and 2 is determined by the heating element width. Partial resistance R and heating element width w are R∝1 / w
There is a relationship.

Since the current value I is constant, the partial power consumption W in the heating elements 1 and 2 is W = I ² R∝1 / w
It is. That is, the partial power consumption W in the heating elements 1 and 2 is in inverse proportion to the heating element width w. Assuming that the partial heat generation amount is proportional to the partial power consumption W, it is derived that the partial heat generation amount is inversely proportional to the heating element width w.

  Based on the above formula, the resistance of the heating element increases at the narrowed portion where the width of the heating element is narrowed, and the amount of heat generated when the same value of current flows also increases.

In the heating element 500 according to the first embodiment of the present embodiment shown in FIG. 5, such a constricted portion is used as the heating element 1a, 2a on the upstream side in the recording material conveyance direction of the heating element 1 and the heating element 2, and the recording material conveyance. The heat generating portions 1c and 2c connecting the heat generating portions 1b and 2b on the downstream side in the direction are provided. The longitudinal width of the boundary portion 3 between the heating element 1 and the heating element 2 is 5 mm. The width of the heating element was set to w ₁ = 2 mm except for the throttle parts (heat generating parts 1c and 2c), while w ₂ = w ₁ × (2/3) = 1.33 mm was set for the throttle part. As a result, the partial heat generation amount of the throttle portion is inversely proportional to the heating element width w, and thus is 1.5 times that of other portions than the throttle portion.

Further, in the heating element 600 according to the second embodiment of the present embodiment shown in FIG. 6, the above-mentioned throttle part is the heating element 1a, 2a on the upstream side in the recording material conveyance direction of the heating element 1 and the heating element 2, and the recording material. The connecting portions 1c and 2c connecting the heat generating portions 1b and 2b on the downstream side in the transport direction are provided. Here, the aperture portions (connection portions 1c and 2c) are conductive patterns that are non-heat generating portions. However, there is no problem with the diaphragm portion as a heat generating portion. The longitudinal width of the boundary part 3 between the heating element 1 and the heating element 2 is 5 mm, and the heating element width is w ₁ = 2 mm except for the throttle part and w ₂ = w ₁ × except for the throttle part as in the first embodiment. (2/3) = 1.33 mm was set, and the throttle portion was provided at the connecting portion side end 5 mm of the heating element 1 and the heating element 2.

  By adopting the heating body configuration described above, the amount of heat generated in the vicinity of the folded portion is transferred to the boundary portion 3 between the heating element 1 and the heating element 2 in the longitudinal direction of the substrate 101, on the substrate 101, and in the fixing sleeve 20. It is propagated through etc. As a result, a shortage of heat at the boundary 3 between the heating element 1 and the heating element 2 can be compensated.

  An LTR size recording material (width: 216 mm) was printed as a large size recording material using an image forming apparatus equipped with the fixing device 10 having the heating element 500 or 600 of this example. Then, compared with the case of using the heating body 400 of Example 2, it was possible to obtain a fixed image having more uniform image characteristics such as gloss and fixability.

  As described above, the effect of the present embodiment described above was shown.

  That is, also in the form of the heating elements 500 and 600 of the present embodiment, the first heating element 1 is provided in the first area from one end of the substrate 101 to a predetermined position. The second heating element 2 is provided in a second area from the other end of the substrate 101 to a predetermined position. The first heating element 1 and the second heating element 2 are substantially line symmetric with respect to a virtual line at the center in the recording material conveyance direction. Therefore, the same operations and effects as those of the first embodiment can be obtained.

  In addition, in the heating elements 500 and 600 of the present embodiment, the heating element width of at least one of the first heating element 1 and the second heating element 2 is narrower than the heating element width at other positions. The configuration is as follows. That is, the heating element width of at least one of the heating elements is at least one of the connecting portions 1c and 2c, the connecting portion side end portion of the first heating portion 1, and the connecting portion side end portion of the second heating portion 2. It is set as the structure where the part narrowed compared with the heat generating body width | variety of another position exists more than a location. As a result, it is possible to further improve the image uniformity such as the fixing property and gloss in the recording material width direction of the fixed image of the large size recording material as compared with the heating body 100 of the first embodiment.

  In the present embodiment, the heating element pattern that can obtain the image uniformity between the heating element boundary portion and the heating element has been described. However, the heating value may be distributed in the heating area of the heating element. . For example, there is a case where a narrowed portion is provided in the vicinity of both longitudinal ends of the heating element. At the longitudinal end, heat generated by the heating element escapes through the substrate in the direction of the longitudinal end, so that the amount of heat generated at the end is increased in order to compensate for the heat radiation. As a result, it is possible to reduce the fixability and insufficient gloss at the end of the recording material.

  In this embodiment, the sizes corresponding to the two heating elements are the B5 size and the LTR size, but it is not necessary to be limited to these sizes. Also, the case where two heating elements are used has been described, but it is not necessary to be limited to two, and three or more heating elements may be used and set to correspond to three or more sizes. good.

[Others]
1) In each embodiment, the heating elements 1 and 2 are configured to have the first heating portions 1a and 2a, the second heating portions 1b and 2b, and the connecting portions 1c and 2c that connect these heating portions. For example, the heating elements 1 and 2 may be composed of a single heating part.

  2) In each embodiment, the case where the heating member is applied to a sleeve fixing type fixing device has been described. However, the heating member is not limited to this and can be applied to a film fixing type fixing device. Further, any fixing device that fixes an image on a recording material using heat heated by a plate heater as a heat source may be used. For example, a sleeve fixing system including a fixing roller, a fixing sleeve suspended from the fixing roller, and a pressure roller that is arranged to face the fixing roller and pressurizes between the fixing roller. The heating body may be configured to be heated, or the fixing roller may be heated by a plate heater.

  3) In the embodiment, an example in which the fixing device 10 is mounted on a so-called ETB type image forming apparatus that directly transfers a toner image onto a recording material sucked and conveyed on the electrostatic transfer conveyance belt has been described. However, the fixing device 10 is not limited thereto, and may be mounted on a so-called ITB type image forming apparatus in which toner of each color is transferred to an intermediate transfer belt and then transferred to a recording material. Further, the fixing device 10 may be mounted on a monochrome laser printer. The fixing device 10 is not limited to a laser printer, and may be mounted on a copying machine. In short, an image forming apparatus that obtains a fixed image by heating an unfixed toner image may be mounted as a device that functions as a fixing device.

It is a figure showing an example of the heater which concerns on Example 1, and is the figure which looked at the heater from the surface in which the heat generating body pattern was formed. It is a figure showing the cross section of the transversal direction of a heater, and the relationship between a heater, a fixing sleeve, and a pressure roller. It is a figure showing an example of the heater which concerns on Example 2, and is the figure which looked at the heater from the surface in which the heat generating body pattern was formed. It is a figure showing an example of the heater which concerns on Example 2, and is the figure which looked at the heater from the surface in which the heat generating body pattern was formed. It is a figure showing an example of the heater which concerns on Example 3, and is the figure which looked at the heater from the surface in which the heat generating body pattern was formed. It is a figure showing an example of the heater which concerns on Example 3, and is the figure which looked at the heater from the surface in which the heat generating body pattern was formed. 1 is a schematic configuration diagram of an example of an image forming apparatus. FIG. 3 is a schematic configuration model diagram of a fixing device. FIG. 3 is a perspective model diagram illustrating a positional relationship among a fixing sleeve, a heater, a main thermistor, and a sub-thermistor in the fixing device. FIG. 3 is a diagram illustrating a layer configuration of a fixing sleeve. It is a top view of the heating body (heater) of the prior art example 1. It is a top view of the heating body (heater) of the prior art example 2.

Explanation of symbols

1: heating element corresponding to a small size recording material, 1a, 1b: heating part, 1c: connection part,
2: heating element corresponding to large size recording material, 2a, 2b: heating part, 2c: connection part,
3: boundary between heating elements, 100, 300, 400, 500, 600: heater (heating element),
101: substrate, 102, 103: electrode, 104: insulating protective layer, 105: sliding protective layer

Claims (12)

In an image heating apparatus having a heating body having a substrate and first and second heating elements provided on the substrate and heating a recording material carrying an image by heat from the heating body,
The first heating element is provided in a first area from one end of the substrate to a predetermined position, and the second heating element is provided from the other end of the substrate to a predetermined position. An image heating apparatus provided in a second area, wherein the first heating element and the second heating element are substantially line symmetric with respect to a virtual line at a center in a recording material conveyance direction.   The apparatus is mounted on an image forming apparatus that conveys a recording material such that one side of the recording material moves along a fixed reference regardless of the size of the recording material. 2. The image heating apparatus according to claim 1, wherein only the body is energized, and the first heating element and the second heating element are energized to generate heat when conveying a large size recording material.   The first heating element and the second heating element are respectively a first heating part, a second heating part downstream of the first heating part in the transport direction, the first heating part, and the second heating element. The image heating apparatus according to claim 1, further comprising: a connecting portion that connects the heat generating portion, wherein the connecting portion includes a heating body that is inclined with respect to the recording material conveyance direction.   The heating element is formed so that a part of the heat generation area in the longitudinal direction of the substrate of the first heating element overlaps with a part of the heat generation area in the longitudinal direction of the substrate of the second heating element. Image heating device   2. The image heating apparatus according to claim 1, wherein at least one of the first heating element and the second heating element has a width of a heating element at a connection portion that is narrower than a width of a heating element at another position.   At least one of the first heating element and the second heating element has a narrower heating element width at the connection part side end of the first heating element or the second heating element than the heating element width at other positions. The image heating apparatus according to claim 1. An image heating apparatus that includes a substrate and first and second heating elements provided on the substrate, and that heats a recording material carrying an image by heat from the first and second heating elements. In the heating element used,
The first heating element is provided in a first area from one end of the substrate to a predetermined position, and the second heating element is provided from the other end of the substrate to a predetermined position. A heating element provided in a second area, wherein the first heating element and the second heating element are substantially line symmetric with respect to a virtual line at a center in a short direction of the substrate. .   The image heating apparatus is mounted on an image forming apparatus that conveys a recording material such that one side of the recording material moves along a fixed reference regardless of the size of the recording material. 8. The heating element according to claim 7, wherein only one heating element is energized, and the first heating element and the second heating element are energized to generate heat when a large-sized recording material is conveyed.   The first heating element and the second heating element are respectively a first heating part, a second heating part arranged in parallel with the first heating part, the first heating part, and the second heating element. The heating body according to claim 7, further comprising: a connecting portion that connects the heat generating portion, wherein the connecting portion is inclined with respect to the recording material conveyance direction.   The heating element is formed so that a part of the heat generation area in the longitudinal direction of the substrate of the first heating element overlaps with a part of the heat generation area in the longitudinal direction of the substrate of the second heating element. Heating body.   The heating element according to claim 7, wherein at least one of the first heating element and the second heating element has a width of the heating element at the connection portion that is narrower than a width of the heating element at other positions.   At least one of the first heating element and the second heating element has a narrower heating element width at the connection part side end of the first heating element or the second heating element than the heating element width at other positions. The heating body according to claim 7.