JP2004095304A - Heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the correct film temperature always stably, and improve durability of the device, in the heating device of film heating type or induction exothermic film type by preventing abnormal temperature rise. <P>SOLUTION: This is a heating device which comprises a heater 5 fixed to the holder 4, a film 2 which is driven with its inner face opposed to the heater 5, and a pressurizing member 6 in which a nip part "n" is formed pressing the film 2, and carries out heat treatment by the heat of the film 2 heated by the heater by introducing and passing the heated member P in the above nip part "n". The heating device has a temperature detecting element 1a which contacts the inner face of the film 2 and the temperature detecting element 1a is installed on a face 1c having a curvature of a temperature detecting element support member 1b. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a heating device that is effective when used as an image heating and fixing device mounted on an image forming apparatus such as a printer or a copying machine, and more particularly to a heating device having a flexible rotating body.
[0002]
[Prior art]
For example, the heating device of the "film heating system" or the "induction heating film system" using a film-shaped rotating body as the flexible rotating body has a significantly higher warm-up time than the heating device of the heating roller system. It has the advantage of being short and has low power consumption, and is currently used in many image forming apparatuses.
[0003]
Further, there has been proposed an apparatus capable of coping with a fixing process of a color image in which unevenness of a toner layer is larger than that of a black and white image by using a film having an elastic layer as a film. That is, since the color image is formed by superposing toner layers of a plurality of colors, the unevenness of the toner layer is larger than that of the black and white image. However, the toner image on the recording material on which the unfixed color toner image is formed and When passing through, the elastic layer is deformed along the toner layer, so that the toner that is unevenly placed on the image is wrapped by the elastic layer and is uniformly heated, so that a uniform color toner image is obtained. Fixation is achieved.
[0004]
A color toner image uniformly fixed in this manner has no gloss unevenness, and particularly has a feature that the image has excellent light transmittance when an OHT (transparent sheet for an overhead projector) is fixed.
[0005]
However, the on-demand property is impaired by the presence of the elastic layer, so it is also proposed to make the base layer of the film a metal or to directly detect the temperature of the film to compensate for the on-demand property impaired by the presence of the elastic layer. Have been.
[0006]
Japanese Patent Application Laid-Open Nos. 8-6413 and 10-161445, for example, directly detect the temperature of such a film. In these, the temperature detecting member is brought into contact with the inside of the heating film, or the temperature detecting element is held on a flat surface of a thin leaf spring or the like, and the temperature detecting element is held on the inner surface of the film by the elasticity of the thin leaf spring or the like as a holding member. To detect the temperature of the film by elastically contacting the film.
[0007]
[Problems to be solved by the invention]
However, a thin film such as a thin metal film, which is a heating film, is generally rigid and flexible, and particularly when a driving force is applied to the film, the shape of the film is constantly changed. There has been a problem that the temperature sensing element side held on the flat surface cannot completely follow it. In this case, there is a problem that a gap is generated between the temperature detecting element and the inner surface of the film, and accurate temperature measurement cannot be performed. In particular, in an on-demand heating device that aims to rapidly start up the device together with power supply by thinning the film and suppressing the heat capacity, the temperature measurement error due to the gap is abnormally high with respect to the set temperature of the heating device. It also causes problems.
[0008]
Therefore, the present invention makes it possible to always detect a stable and accurate temperature of a rotating body (film) in a heating apparatus such as a film heating method using a flexible rotating body or an induction heating film method, thereby detecting abnormalities in the rotating body. An object of the present invention is to prevent a temperature rise or the like beforehand and improve the durability of the apparatus.
[0009]
[Means for Solving the Problems]
The present invention is a heating device having the following configuration.
[0010]
(1) A first pressing member, a flexible rotating body that rotates around the first pressing member, and a nip portion formed between the first pressing member and the rotating body. In a heating device having a second pressing member and a temperature detecting member that is in contact with the inner surface of the rotating body, and heating the nip portion between the rotating body and the second pressing member through the material to be heated,
The temperature detection member has a leaf spring-like support portion having a curvature on a free end side in a state where no load is applied, and a temperature detection element attached to a portion of the support portion having a curvature. And a heating device.
[0011]
(2) The heating according to (1), wherein the free-end-side tip of the support portion slightly floats from the inner surface of the rotating body while the temperature detecting member is in contact with the inner surface of the rotating body. apparatus.
[0012]
(3) The heating device according to (1), wherein a radius of curvature of a free end side of the support portion is equal to or smaller than a radius of curvature of a contact portion of the rotating body with the temperature detecting member.
[0013]
(4) The heating device according to (1), wherein the first pressure member holds a heating element that generates heat when energized.
[0014]
(5) The heating device according to (1), wherein the rotating body has a conductive layer, and the first pressing member holds a coil for generating an eddy current in the conductive layer.
[0015]
(6) The heating device according to (1), wherein the rotating body has a metal layer and an elastic layer.
[0016]
<Operation>
That is, in the present invention, the inner surface of the rotating body and the temperature detection are provided by having a curvature surface smaller than the inner surface of the flexible rotating body (film) at the tip of the leaf spring-like supporting portion holding the temperature sensing element. By improving the contact property of the element and following the inner surface of the rotating body which is driven and deformed, the temperature of the flexible rotating body can be always detected stably and accurately. This prevents abnormal heating of the rotating body, etc., and improves the durability of the apparatus.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
<First embodiment>
(1) Example of image forming apparatus
FIG. 1 shows a schematic configuration diagram of a color image forming apparatus as one embodiment of the present invention. The image forming apparatus of this example is a color image forming apparatus that obtains a full-color image by superimposing four color toner images of yellow, cyan, magenta, and black using an electrophotographic method.
[0018]
In this color image forming apparatus, a photosensitive drum (1Y, 1C, 1M, 1K) as an image carrier, a charging roller (2Y, 2C, 2M, 2K) as a charging unit, and an electrostatic latent image are visualized. And the so-called all-in-one cartridges Y, C, M, and K in which the developing means (3Y, 3C, 3M, and 3K) and the photosensitive drum cleaning means (4Y, 4C, 4M, and 4K) are combined in one container. I'm using
[0019]
That is, a yellow cartridge Y filled with a yellow toner in a developing device, a cyan cartridge C filled with a cyan toner in a developing device, a magenta cartridge M filled with a magenta toner in a developing device, and a black cartridge K filled with a black toner in a developing device Are used.
[0020]
The optical system (5Y, 5C, 5M, 5K) that forms an electrostatic latent image by exposing the photosensitive drums (1Y, 1C, 1M, 1K) in each of the cartridges Y, C, M, and K has the above-mentioned configuration. It is provided corresponding to the color toner cartridge. As the optical system, a laser scanning exposure optical system is used.
[0021]
Scanning light based on image data from the optical system (5Y, 5C, 5M, 5K) is uniformly charged by the charging means (2Y, 2C, 2M, 2K) to the photosensitive drums (1Y, 1C, 1M, 1K), an electrostatic latent image corresponding to an image is formed on the surface of the photosensitive drum (1Y, 1C, 1M, 1K). By setting the developing bias applied to the developing rollers (3Y, 3C, 3M, 3K) from a bias power supply (not shown) to an appropriate value between the charging potential and the latent image (exposed portion) potential, negative polarity is obtained. Is selectively adhered to the electrostatic latent images on the photosensitive drums (1Y, 1C, 1M, 1K), thereby performing development.
[0022]
The monochromatic toner image developed on the photoconductor drums (1Y, 1C, 1M, 1K) is transferred to the intermediate transfer body 36 that rotates at substantially the same speed in synchronization with the photoconductor drums (1Y, 1C, 1M, 1K). Transcribed up. In the present embodiment, an intermediate transfer belt 36 is used as an intermediate transfer member. The intermediate transfer belt 36 is wound around a driving roller 37, a secondary transfer roller facing roller 44, and a tension roller 38 and stretched by the tension roller 38. 37 drives it to rotate.
[0023]
Primary transfer rollers (9Y, 9C, 9M, 9K) are used as primary transfer means for transferring the toner images on the photosensitive drums (1Y, 1C, 1M, 1K) to the intermediate transfer belt 36. The primary transfer roller (9Y, 9C, 9M, 9K) is applied with a primary transfer bias having a polarity opposite to that of the toner from a bias power supply (not shown), so that the toner image is primarily transferred to the intermediate transfer belt 36. Is done.
[0024]
After the primary transfer, the toner remaining on the photosensitive drums (1Y, 1C, 1M, 1K) as transfer residues is removed by cleaning means (4Y, 4C, 4M, 4K). In this embodiment, blade cleaning using a urethane blade is used as the cleaning means.
[0025]
The above steps are performed for each color of yellow, magenta, cyan, and black in synchronization with the rotation of the intermediate transfer belt 36, and primary transfer toner images of each color are sequentially superimposed on the intermediate transfer belt 36. At the time of forming an image of only a single color (single color mode), the above steps are performed only for the target color.
[0026]
The recording material P set in a recording material cassette 40 serving as a recording material (transfer material) supply unit is fed by a feed roller 41, and is sent to a secondary transfer unit at a predetermined timing by a registration roller 42. Is conveyed to the nip between the intermediate transfer belt 36 and the secondary transfer means 43.
[0027]
The primary transfer toner image formed on the intermediate transfer belt 36 is applied to a secondary transfer roller 43 as a secondary transfer unit by a bias having a polarity opposite to that of the toner, which is applied by a bias applying unit (not shown). The batch is transferred to the top.
[0028]
The secondary transfer residual toner remaining on the intermediate transfer belt 36 after the secondary transfer is removed by the intermediate transfer belt cleaning unit 45. In this embodiment, the intermediate transfer member is cleaned by a urethane blade, similarly to the cleaning means of the photosensitive drum.
[0029]
The toner image secondary-transferred onto the recording material P is fused and fixed on the recording material P by passing through a fixing device F serving as a fixing unit, and becomes an output image of the image forming apparatus.
[0030]
(2) Fixing device F
1) Description of overall configuration of fixing device F
FIG. 2 is an enlarged cross-sectional model view of the fixing device F. FIG. 3 is a side view of the gear train installation side, and FIG. 4 is an exploded perspective view of a main part.
[0031]
The fixing device F is a color heating-on-demand fixing device of a film heating type, in which a cylindrical film (fixing film) as a heating film (flexible rotating body) is pressed with a pressing roller as a second pressing member. This is a heating device having a pressing member driving configuration that is driven to rotate by being driven to rotate.
[0032]
Reference numeral 7 denotes an apparatus frame. Between both front and rear side plates 71a and 71b of the apparatus frame 7, the shafts at both ends of an elastic pressure roller 6 as a second pressure member are freely rotatable via bearings. It is arranged with bearing support. The elastic pressure roller 6 is formed, for example, by forming a silicone rubber layer and a release layer on a cored bar.
[0033]
10 is a film assembly as a heating member,
▲ 1 ▼. A horizontally long metal rigid stay 3 with a U-shaped cross section,
▲ 2 ▼. A film guide 4 serving as a first pressing member also serving as a horizontally long heater holder made of a heat-resistant resin having a substantially semicircular cross section and having a cross section fixed and supported on the stay 3;
(3). A horizontally long ceramic heater 5 as a heating element which is fitted and fixedly supported in a groove provided along the longitudinal direction of the guide on the lower surface of the film guide 4;
▲ 4 ▼. A thermistor unit 1 as a temperature detecting means (temperature detecting member) disposed inside the film guide 4;
▲ 5 ▼. A cylindrical film (fixing film, sleeve) 2 as a heating film (rotating body) loosely fitted to the assembly of the stay 3, the film guide 4, the heater 5, and the thermistor unit 1.
▲ 6 ▼. Annular flange members 8a and 8b for restricting the shift of the film fitted to the front and rear ends of the film guide 4
And so on.
[0034]
The above-mentioned film assembly 10 is arranged such that the heater 5 side faces downward, and the front and back side annular flange members 8a are provided between the front and back side plates 71a and 71b of the apparatus frame 7 on which the pressure roller 6 is already disposed. 8b is fitted into the lower opening slit holes 7a and 7b provided on the front and rear side plates 71a and 71b, respectively, and is dropped on the upper surface of the pressure roller 6 to be disposed. I do.
[0035]
Reference numeral 19 denotes a pressurizing frame, which is held swingably about the fulcrum 19a with respect to the apparatus frame 7. The pressing frame 19 is rotationally urged by the pressing spring 18 in a direction of pressing the front and rear ends of the film assembly 10 downward against the elasticity of the pressing roller 6, respectively. The downward heater 10 is pressed against the upper surface of the pressure roller 6 with a constant pressure against the upper surface of the pressure roller 6 with the film 2 interposed therebetween, thereby forming a fixing nip portion n having a predetermined width.
[0036]
Further, a discharge guide 21 for guiding the recording material P is attached to the downstream side of the fixing nip portion n in the recording material conveyance direction so as to be able to pivot about a rotation fulcrum 21a. A paper discharge roller 11 for transporting the recording material P together with 21 is in contact with the apparatus frame 7 by the spring force of a paper discharge spring 22 and is positioned. Reference numeral 11a denotes a pinch roller for the discharge roller 11.
[0037]
Further, a sensor lever 9 for detecting the passage or stagnation of the recording material P is provided in an upper paper discharge guide 23 for guiding the upper portion of the recording material P. The sensor lever 9 is swingably mounted. When the recording material P passes, the lever portion 9b of the sensor lever 9 is pushed up by the recording material P and rotated, so that a flag provided at an end of the sensor lever 9 is provided. 9a is configured to block the light receiving portion of the paper discharge sensor 20 provided in the image forming apparatus main body, and to detect the passage or stagnation of the recording material P based on the light blocking time.
[0038]
In the gear train of FIG. 3, the driving force transmitted from a driving source (not shown) on the image forming apparatus main body side is usually a pressure roller via a first idler gear 12, a second idler gear 13, and a third idler gear 14. The pressure roller 6 rotates counterclockwise in FIG. 2 by being transmitted to the pressure roller gear 15 fixed to 6. The paper discharge roller 11 also receives power transmission via the gear trains 15, 16a, 16b, and 17 and rotates in the paper discharge direction at a peripheral speed substantially equal to the rotational peripheral speed of the pressure roller 6.
In the present embodiment, the cylindrical fixing film 2 as a heating film is a flexible member formed by covering a cylindrical thin metal film as a base and coating an outer peripheral surface thereof with a silicone rubber layer as an elastic layer. It is. The cylindrical thin metal film as the base layer is, for example, a Ni electroformed film having a thickness of about 50 μm. The thickness of the silicone rubber layer is desirably as large as possible from the viewpoint of image quality such as OHT transparency and "spot" (fine gloss unevenness) on an image. However, if the thickness is large, on-demand properties are impaired. According to the study of the present inventors, it has been found that a rubber layer thickness of 50 μm or more is necessary to obtain a satisfactory level of image quality.
[0039]
Further, by providing a fluororesin layer on the surface of the fixing belt 20, the releasability of the surface is improved, and the offset phenomenon that occurs when toner temporarily adheres to the surface of the fixing belt 20 and moves to the transfer material P again is reduced. Can be prevented.
[0040]
The heater 5 as a heating element is a ceramic heater in this example, and is formed of a horizontally long heater substrate made of alumina, aluminum nitride, or the like having a length perpendicular to the paper passing direction, and formed on the heater substrate surface along the substrate length. Silver-palladium, Ta ₂ The resistance heating element such as N is used as a basic component, and has a low heat capacity as a whole, and the temperature is quickly raised by energizing the resistance heating element.
[0041]
The thermistor unit 1 includes a stationary seat portion 1d, an elongated thin leaf spring portion (leaf spring-like supporting portion) 1b as a temperature sensing element support portion having a base fixed to the stationary seat portion 1d, and an elongated thin leaf spring portion 1b. A temperature detecting element (thermistor element) 1a fixedly disposed on the front end surface 1c, a stationary portion 1d fixed to the film guide 4, and the temperature detecting element 1a attached to the inner surface of the film 2 by an elongated thin plate spring portion 1b. Are arranged in contact with each other under pressure due to the bending elasticity.
[0042]
The elongated thin plate spring portion 1b has a curvature on the free end side in a state where no load is applied, and the temperature detecting element 1a is attached to a portion having the curvature. The radius of curvature of the elongated thin plate spring portion 1b on the free end side is equal to or smaller than the radius of curvature of the portion of the film 2 in contact with the temperature detecting element. In the state where the temperature detecting element 1a is in contact with the inner surface of the film 2, the free end side tip of the elongated thin plate spring portion 1b slightly floats from the inner surface of the film.
[0043]
The temperature detecting element 1a is electrically connected to a control circuit (CPU) (not shown) via an elongated thin plate spring 1b and a seat 1d, and the control circuit includes a film 2 detected by the temperature detecting element 1a. Based on the inner surface temperature information, the control content of the temperature control of the heater 5 is determined, and the power supply to the heater 5 is controlled. The energization of the heater 5 is controlled by, for example, PID control, and the input power is controlled so that the inner surface temperature of the film 2, that is, the temperature detected by the temperature detecting element 1a is maintained at a predetermined set temperature.
[0044]
In normal use, the driven rotation of the film 2 starts when the rotation of the pressure roller 6 starts, and the inner surface temperature of the film 2 rises with the temperature rise accompanying the energization of the heater 5.
[0045]
That is, in FIG. 2, when the pressure roller 6 is driven to rotate in the counterclockwise direction indicated by the arrow, the rotational force is applied to the film 2 by the frictional force between the pressure roller 6 and the outer surface of the film 2 in the fixing nip n. Acting, the inner surface of the film slides in close contact with the lower surface, which is the surface of the heater 5, in the fixing nip portion n, and rotates around the outer periphery of the film guide 4 in the clockwise direction of the arrow following the rotation of the pressure roller 6. I do. The film guide 4 holds the film 2 and plays a role in guiding the rotation of the film 2. In this case, in order to reduce the sliding resistance between the inner surface of the film 2 and the lower surface of the heater 5 on which the film 2 slides, a lubricant such as heat-resistant grease is interposed between the two to secure the sliding property.
[0046]
When the pressure roller 6 is driven to rotate, the film 2 is driven to rotate accordingly, and the heater 5 rises to a predetermined fixing temperature and the temperature is adjusted. During this time, the recording material P that has passed through the secondary transfer nip as described above is guided by the entrance guide 24 of the fixing device F, introduced into the fixing nip n, and nipped and conveyed. The unfixed toner image side of the recording material P is the film 2 side. In the process in which the recording material P is nipped and conveyed through the fixing nip portion n, the unfixed toner image on the recording material P is received by the heat from the heater 5 via the film 2 and the pressure of the fixing nip portion n. The recording material P is heated and fixed on the surface. The recording material P that has exited the fixing nip portion n is separated from the surface of the film 2 and is discharged and conveyed by discharge rollers 11a.
[0047]
The entrance guide 24 is assembled to the apparatus frame 7 and serves to guide the recording material P so that the recording material P that has passed through the secondary transfer nip is accurately guided to the fixing nip portion n.
[0048]
2) Arrangement configuration of temperature detecting element 1a
▲ 1 ▼. Conventional configuration
In the above-described fixing device configuration, for example, FIGS. 8 to 10 show an example of a conventional example, and the shape of a distal end surface portion 1c on which a temperature detecting element 1a of an elongated thin plate spring portion 1b as a temperature detecting element supporting portion is fixedly arranged is set. If the flat surface remains, the distal end surface portion 1c of the spring portion 1b comes into contact with the inner surface of the film 2 first, and the temperature detecting element 1a to be originally brought into contact with the inner surface of the film 2 cannot be accurately detected. This occurs when the film 2 relatively rotates along the film guide 4 as shown in FIG. 8, when the film 2 is separated from the film guide 4 by a driving force as shown in FIG. In the case where the film 2 sags extremely downstream as shown in FIG. 2, the temperature sensing element 1a to be originally brought into contact at any position other than the specific angle coincident with the tangential direction is also higher than the inner surface of the film 2. It was difficult to accurately detect the temperature at a distance.
[0049]
▲ 2 ▼. Configuration of the present embodiment
The elongated thin plate spring portion 1b has a curvature on the free end side in a state where no load is applied, and the temperature detecting element 1a is attached to a portion having the curvature. The radius of curvature of the elongated thin plate spring portion 1b on the free end side is equal to or smaller than the radius of curvature of the portion of the film 2 in contact with the temperature detecting element. In the state where the temperature detecting element 1a is in contact with the inner surface of the film 2, the free end side tip of the elongated thin plate spring portion 1b slightly floats from the inner surface of the film.
[0050]
That is, as shown in FIGS. 5 to 7, the distal end surface portion 1 c of the elongated thin plate spring portion 1 b as the temperature detecting element support portion, in which the temperature detecting element 1 a is fixedly arranged, has the same shape as at least the curvature of the film 2. A curved surface having a curvature equal to or less than that is provided, and the temperature detecting element 1a is fixedly disposed on the curved surface. That is, the temperature detecting element is arranged at the R portion of the thin plate spring 1b having a rounded tip at the downstream end from the vicinity of the fixing nip portion on the inner surface of the film.
[0051]
The distal end surface portion 1c of the elongated thin plate spring portion 1b serving as a temperature detection element support portion, on which the temperature detection element 1a is fixed, is formed into a curved surface shape having, for example, about one fifth of the curvature of the film 2. As shown in FIG. 5, even when the film 2 relatively rotates along the film guide 4, the temperature detecting element portion 1a is in close contact with the inner surface of the film 2. Similarly, when the film 2 is separated from the film guide 4 by the driving force as shown in FIG. 6, or when the film 2 is extremely slack downstream as shown in FIG. 2 is in close contact with the inner surface.
[0052]
From this, the temperature detecting element 1a accurately detects the inner surface temperature of the film 2, sends the information to the control circuit unit, and the control circuit unit determines whether or not the temperature is appropriate for the preset temperature, and determines from the power supply device. The film 2 is controlled to an appropriate temperature by controlling the electric power supplied to the heater 5. As a result, the recording material P is caught in the fixing nip n formed between the film 2 heated to a certain temperature and the rotating pressure roller 6. As a result, heat appropriate to the pressure and paper type is applied, and the unfixed toner is softened and melted, and is pressed against the recording material P and cooled to form a permanently fixed image.
[0053]
In other words, it is difficult to stably detect the temperature at the heater 5 due to the thermal conductivity of the rubber (elastic layer). A rubber surf fuser (a film heating type heating device using a film to which an elastic layer is added as a heating film). In this case, accurate temperature in the vicinity of the fixing nip was detected, and stable temperature control became possible.
[0054]
3) Other
In the above-described embodiment, the heating film 2 may have a heat resistant resin film as a base layer. An elastic layer or a release layer may be omitted. In addition, a multi-layer structure in which other functional layers are added can be employed.
[0055]
The temperature detecting element 1a can be, for example, a thermocouple other than the thermistor element.
[0056]
The heater 5 as a heating element can be an electromagnetic induction heating member such as an iron plate other than the ceramic heater.
[0057]
The heater 5 as a heating element does not always need to be located at a position corresponding to the fixing nip portion n, and may be disposed at a position shifted upstream of the fixing nip portion n in the film rotation direction.
[0058]
<Second embodiment>
In the first embodiment, a fixing device of a film heating type using the heater 5 is taken as an example, but the present invention is not limited to this. For example, the film has a ferromagnetic conductive layer (heating layer). A magnetic force is generated by applying a high-frequency bias from an exciting circuit to an exciting coil as a magnetic field generating means, and an induced current (eddy current) is generated in the ferromagnetic conductive layer of the film by the action of the magnetic force. A similar effect can be obtained by applying the present invention to a heating device of the "method".
[0059]
FIG. 11 shows an example thereof. The film guide 4 has a substantially cylindrical shape, and a magnetic field generating means 25 composed of a magnetic core 25a and an exciting coil 25b is arranged in a substantially right half of the inner space. The lower surface of the film guide 4 is a nip forming portion, and a film sliding member 26 is disposed there. Reference numeral 2A denotes a cylindrical induction heating film as a heating film having a heating layer for generating electromagnetic induction heat, which is loosely fitted to the film guide 4. A fixing nip n is formed between the film sliding member 26 and the elastic pressure roller 6 with the induction heating film 2A interposed therebetween.
[0060]
As in the case of the above-described embodiment, the induction heating film 2 </ b> A is driven to rotate while the inner surface is in close contact with the lower surface of the film sliding member 26 by the rotational driving of the elastic pressure roller 6.
[0061]
An excitation circuit 101 applies a high-frequency bias to the excitation coil 25b of the magnetic field generating means 25. As a result, the magnetic field generating means 25 generates a high-frequency magnetic field, and an induced current is generated in the heat generating layer of the induction heat generating film 2A by the action of the magnetic field, so that the heat generating layer generates heat and the film 2A is heated.
[0062]
The inner surface temperature of the induction heating film 2A is detected by the temperature detecting element 1a brought into contact with the inner surface of the film, and the detected temperature information is input to the control circuit unit 100. The control circuit unit 100 determines the content of the temperature control of the film 2A based on the inner surface temperature information of the film 2A detected by the temperature detecting element 1a, and controls the energization to the exciting coil 25b of the magnetic field generating means 25. That is, energization of the excitation coil 25b is controlled so that the temperature detected by the temperature detecting element 1a is maintained at a predetermined set temperature.
[0063]
Then, the recording material P is introduced between the film 2A of the fixing nip n and the elastic pressure roller 6 and is nipped and conveyed, and receives heat of induction heat of the film 2A and pressure of the fixing nip n to receive the recording material P. The unfixed toner image on the recording material P is heated and fixed on the surface of the recording material P.
[0064]
Also in this embodiment, as in the previous embodiment, the distal end surface portion 1c of the elongated thin plate spring portion 1b serving as the temperature sensing element support portion, in which the temperature sensing element 1a is fixedly arranged, has a shape at least corresponding to the curvature of the film 2A. The temperature sensing element 1a is fixedly disposed on the curved surface portion having the same or less curvature, and the same effect as that of the above embodiment is obtained.
[0065]
<Others>
1) The second pressing member is not limited to the roller body. A belt body that can be driven to rotate can also be used. The pressing member can also be configured to be heated by a heat source.
[0066]
2) The image forming principle and process for the recording material of the image forming apparatus are appropriate.
[0067]
3) The heating device of the present invention is not limited to the heating and fixing device of the embodiment, but may be any other type of image heating device, an image heating device that reheats a recording material bearing an image to improve surface properties such as luster, It can also be used as a heating device or the like that can be used for heat treatment such as drying, heat lamination, hot press wrinkle removal, and hot press decurling by passing a sheet-shaped material to be heated.
[0068]
【The invention's effect】
As described above, according to the present invention, a heating apparatus using a flexible rotating body, such as a “film heating method” or an “induction heating film method”, has conventionally been provided with an inner surface shape of a flexible rotating body. In conventional temperature sensing elements (such as inscribed thermistors), which could not follow the change and the detected temperature was different, the element attachment part has a curvature to prevent the change in shape of the flexible rotating body. As a result, the element portion can always be brought into contact with the inner surface of the rotating body, thereby enabling more stable and accurate detection of the inner surface temperature of the rotating body.
[0069]
As a result, in the image heating and fixing apparatus, not only is the performance of the fixing apparatus itself improved, such as stability of the fixing property and prevention of uneven gloss due to a temperature change in one sheet, but also efficient power supply becomes possible, thereby saving power. It is also effective for resource utilization. Similarly, stable temperature detection is possible even for rapid startup, preventing runaway and improving safety, and enabling the supply of an on-demand fixing device that enables faster startup. Was.
[Brief description of the drawings]
FIG. 1 is a schematic configuration model diagram of an image forming apparatus according to a first embodiment.
FIG. 2 is an enlarged schematic cross-sectional view of a fixing device.
FIG. 3 is a schematic side view of the fixing device on the gear train side.
FIG. 4 is an exploded perspective view of a main part of the fixing device.
FIG. 5 is an explanatory diagram (part 1) of a contact state of a temperature detection element with an inner surface of a film.
FIG. 6 is an explanatory view (No. 2) of a contact state of a temperature detecting element to an inner surface of a film.
FIG. 7 is an explanatory view (part 3) of a contact state of the temperature detecting element with the inner surface of the film.
FIG. 8 is an explanatory view (part 1) of a contact state of a temperature detecting element to an inner surface of a film in a conventional fixing device.
FIG. 9 is an explanatory diagram (part 2) of a contact state of a temperature detecting element to an inner surface of a film in a conventional fixing device.
FIG. 10 is an explanatory view (part 3) of a contact state of a temperature detecting element with an inner surface of a film in a conventional fixing device.
FIG. 11 is a schematic diagram illustrating the configuration of a fixing device according to a second embodiment.
[Explanation of symbols]
1 ‥‥ Thermistor unit, 2 ‥ Film (rotating body), 3 ‥ Stay, 4 ‥ Film guide (first pressing member), 5 ‥ Heater, 6. ‥ Pressurizing roller (2nd pressing member) )

Claims (6)

A first pressing member, a flexible rotator rotating around the first pressing member, and a second nip formed with the first pressing member with the rotator interposed therebetween. In a heating device having a pressing member and a temperature detecting member that is in contact with the inner surface of the rotating body, and heating the material to be heated through a nip portion between the rotating body and the second pressing member,
The temperature detection member has a leaf spring-like support portion having a curvature on a free end side in a state where no load is applied, and a temperature detection element attached to a portion of the support portion having a curvature. And a heating device. The heating device according to claim 1, wherein a free end side tip of the support portion slightly floats from the rotating body surface in a state where the temperature detecting member is in contact with the rotating body surface. The heating device according to claim 1, wherein a radius of curvature of a free end side of the support portion is equal to or smaller than a radius of curvature of a contact portion of the rotating body with the temperature detecting member. The heating device according to claim 1, wherein the first pressing member holds a heating element that generates heat when energized. The heating device according to claim 1, wherein the rotating body has a conductive layer, and the first pressing member holds a coil for generating an eddy current in the conductive layer. The heating device according to claim 1, wherein the rotating body has a metal layer and an elastic layer.

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