JP2015158535A - fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device that has accelerated the start-up, and has suppressed the situation where a recording material is drawn to a side opposite to a cylindrical rotating body at a rear end of a fixing nip part to cause paper jam.SOLUTION: A fixing device includes a cylindrical rotating body, an opposing body that is arranged opposite to the cylindrical rotating body to form a fixing nip part fixing a toner image on a recording material with the cylindrical rotating body, and a heating target metallic plate that is in slide contact with the inner peripheral surface of the cylindrical rotating body inside the cylindrical rotating body corresponding to the fixing nip part to receive radiation heat from a heating element. The heating target metallic plate is folded in a direction separated from a recording material conveyance path at a rear end in the recording conveyance direction of the fixing nip part, and temperature detection means is provided at an extension part extended from the folded part or at a position opposite to the extension part.

Description

  The present invention relates to a fixing device in an electrophotographic image forming apparatus such as a printer, a copying machine, or a facsimile.

  2. Description of the Related Art Conventionally, in electrophotographic printers, copying machines, facsimiles, and the like, toner is used as a developer, a toner image is formed on a recording material by electrostatic image forming means, and then a recording material is applied by fixing means. The toner image is melted and fixed by heating and pressing to form an image.

  In recent years, there has been a fixing device in which a metal plate to be heated is arranged in a fixing nip portion so as to replace the function of a conventional ceramic heater, and this is heated in a non-contact manner by a halogen heater in a non-contact manner, thereby speeding up startup. It has been proposed (Patent Document 1).

  FIG. 5A shows a side view of the halogen heater film heating type fixing device 12c. In this halogen heater type film heating type fixing device, a pressure roller is kept the same as a conventional pressure roller, while a heat roller type halogen heater is used as a heater, and a thin metal film having a structure similar to the fixing film as a fixing roller. 16 is used.

  Further, a halogen heater film guide 18 and a halogen heater metal pressure stay 19 are provided. An upper cover stay 17 is provided to prevent the metal pressure stay 19 and the wiring members of the internal electrical components from contacting the fixing film 16.

  Further, a radiation light reflecting member 20 provided for concentrating the radiation light of the halogen heater 13a on the fixing nip portion and a heated metal plate 21 are provided. The metal plate 21 to be heated forms a fixing nip while sliding with the fixing film 16 that rotates and moves between the pressure roller 14 and the function of heating and receiving radiation light reflected by the reflecting member 20. It also functions as a fixed pressure member. Further, a black coating layer 21a is formed on the heater side surface of the metal plate 21 to be heated to enhance the absorption of radiation light.

  In FIG. 5A, the recording material is conveyed from the right side toward the paper surface, passes through the fixing nip portion, and is discharged to the left side of the paper surface. As a feature of this method, the upper fixing unit on the rear end side of the discharged fixing nip portion protrudes from the nip width greatly toward the downstream side. As a result, the fixing film 16 has a longer horizontal transport area before and after the fixing nip portion than the conventional example, and requires a film that is large relative to the fixing nip width in terms of film size.

  As a factor having such characteristics, the internal structure will be described in more detail with reference to the cross-sectional view of FIG. First, the nip downstream side of the metal plate 21 to be heated is extended in the horizontal direction on the downstream side through a one-stage bent portion, and a contact thermistor 22 is provided on the upper surface portion thereof. That is, the contact type thermistor 22 is configured to be in pressure contact with the upper pressure spring 22 a and the upper cover stay 17 screwed to the film guide 18.

  In this system, the method of detecting the contact surface temperature or contactless surface temperature in the conventional heat roller fixing device cannot be used due to insufficient rigidity of the fixing film or position instability. Further, it cannot be formed on the upper surface of the heater as in a film heating type fixing device using a ceramic heater for radiation heating.

  For this reason, as a configuration for detecting a temperature closer to the temperature of the fixing nip portion, a temperature detecting portion is provided at the downstream side of the fixing nip of the heated metal plate by utilizing the thermal conductivity of the metal plate. Therefore, it is necessary to extend a part of the downstream side in this way.

  FIG. 6 is a perspective view of main fixing parts for easily explaining the shape and arrangement of these parts. 6A is an upper cover stay 17, FIG. 6B is a film guide stay 18, FIG. 6C is a metal pressure stay 19, FIG. 6D is a radiation reflecting member 20, FIG. E) shows the halogen heater 13a. FIG. 6F shows a thermistor 22 disposed at the fixing central portion and the end portion, and a thermo switch 22a disposed at the central portion. FIG. 6G shows a heated metal plate having a shape in which the three temperature sensor contact seats 21b are partially extended to the downstream side in order to secure the contact location between the thermistor 22 and the thermo switch 22a. 21 are shown.

  Here, each temperature sensor is abutted through three temperature sensor abutting square holes 18a opened in a film guide stay 18 (not shown).

JP 2012-212066 A

  However, in Patent Document 1, there is a concern that jamming may occur due to winding around the pressure roller. That is, when the paper passing durability is actually advanced, the surface of the fixing film or the pressure roller may be caused by adhesion of foreign matter such as paper dust of the recording paper as a recording material or its additive, or surface scraping by the edge of the paper. The releasability decreases.

  When the toner adheres during fixing, if the adhesion to the back of the paper increases due to toner contamination on the surface of the pressure roller, the separation angle to the fixing side is not provided at the rear end of the fixing nip portion. A force is exerted by the roller surface to pull the recording material downward. On the other hand, the rear end paper discharge portion of the fixing nip portion of the upper fixing unit only tries to keep the recording material horizontal. For this reason, as shown in FIG. 7, at the rear end (exit) of the fixing nip portion, the recording material is attracted and wound on the pressure roller side (side facing the fixing film, which is a cylindrical rotating body), leading to jamming. The possibility increases.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device that suppresses the occurrence of jamming due to the recording material being attracted to the side facing the cylindrical rotating body at the rear end of the fixing nip portion as well as increasing the startup speed. It is in.

  In order to achieve the above object, a fixing device according to the present invention includes a cylindrical rotating body and a fixing nip that faces the cylindrical rotating body and fixes a toner image on a recording material together with the cylindrical rotating body. And a metal plate to be heated that slides on the inner peripheral surface of the cylindrical rotating body within the cylindrical rotating body corresponding to the fixing nip portion and receives radiant heat from the heating element A fixing device having the fixing nip portion bent at a rear end portion in the recording material conveyance direction of the fixing nip portion in a direction away from the recording material conveyance path, or a bent extension portion, or the extension portion. A temperature detecting means is provided opposite to the above.

  According to the present invention, it is possible to provide a fixing device which can suppress the occurrence of a jam by attracting a recording material to the side facing the cylindrical rotating body at the rear end of the fixing nip portion as well as increasing the startup speed. Can do.

(A) is explanatory drawing of the arrangement configuration in the fixing device which concerns on the 1st Embodiment of this invention, (B) is a perspective view of the to-be-heated metal plate which concerns on 1st Embodiment. 1 is an explanatory diagram of an overall configuration of an image forming apparatus equipped with a fixing device according to an embodiment of the present invention. (A) is explanatory drawing of the arrangement structure in the fixing device which concerns on the 2nd Embodiment of this invention, (B) is a perspective view of the to-be-heated metal plate which concerns on 2nd Embodiment. (A) is explanatory drawing of arrangement | positioning structure in the fixing device which concerns on the 3rd Embodiment of this invention, (B) is explanatory drawing of non-contact arrangement | positioning of a temperature detection part, (C) is a perspective view of a to-be-heated metal plate. is there. (A) is a side view showing a conventional fixing device, and (B) is a sectional view of the conventional fixing device. FIG. 7 is a perspective view illustrating the shapes of main components of a conventional fixing device, in which (A) is an upper cover stay, (B) is a film guide stay, (C) is a metal pressure stay, and (D) is radiation light. A reflective member, (E) a halogen heater, (F) a thermistor disposed at the fixing central and end portions, a thermoswitch disposed at the central portion, and (G) a heated metal plate. FIG. 10 is a diagram for explaining a state when a paper pressure roller winding jam occurs during fixing in a conventional fixing device.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<< First Embodiment >>
(Image forming device)
FIG. 2 is a diagram showing an overall configuration of an electrophotographic monochrome printer as an image forming apparatus equipped with a fixing device according to an embodiment of the present invention. In FIG. 2, the surface of the photosensitive drum 2 is uniformly charged to a predetermined polarity by the charging roller 1, and then only the area where the photosensitive drum 2 is exposed by the exposure means 3 such as a laser is neutralized to be placed on the photosensitive drum 2. A latent image is formed.

  The latent image is obtained by frictionally charging the toner 5 of the developing device 4 between the developing blade 4a and the developing sleeve 4b to the same polarity as the surface of the photosensitive drum, and then conveying the toner 5 to the opposite portion of the photosensitive drum and the developing sleeve. A bias is applied in a superimposed manner, and the image is developed by floating vibration by an electric field effect. The toner image portion formed by being selectively adhered onto the photosensitive drum 2 is conveyed to the transfer nip portion formed by the transfer roller 6 and the photosensitive drum 2 by the rotation of the photosensitive drum 2.

  In addition to the non-contact method described above, contact development in which the toner is selectively attached to the latent image forming portion of the photosensitive drum by applying a DC bias while the elastic developing roller is in contact with the photosensitive drum. There are also methods.

  On the other hand, the recording material 7 such as paper on which an image is recorded is fed from the recording material storage box 7a to the vertical conveyance roller pair 7d by the paper feed roller pair 7c and then transferred by the vertical conveyance roller pair before transfer. It is conveyed to the conveyance roller 7e. Further, the recording material is conveyed by the pre-transfer conveying roller to the transfer nip portion along the transfer guide plate 9 at a predetermined entry angle. Then, the charge eliminating brush 8 for removing unnecessary charging on the surface of the recording material is brought into contact with the back side of the recording material being conveyed, and then discharged to the transfer nip portion.

  In the transfer nip portion, the toner on the photosensitive drum is electrostatically attracted and moved to the recording material side. For this reason, the transfer charge for continuously holding the toner by charging the back surface of the recording material with the reverse polarity to the toner while applying a high voltage of the reverse polarity to the toner to the transfer roller 6 on the back surface of the recording material. To grant.

  Finally, the recording material onto which the toner image has been transferred is conveyed to a fixing nip portion of the fixing device 12 including the heating rotator 16 and the pressure roller 14. In the fixing nip portion, the toner image is fixed by heating and pressurizing while being controlled at a constant temperature by a constant temperature control means (not shown) provided on the heating rotator 13 side so as to maintain a preset fixing temperature. .

  A slight amount of deposits such as toner having different polarities remain on the surface of the photosensitive drum 2 after the toner image is transferred. For this reason, the surface of the photosensitive drum 2 after passing through the transfer nip portion is scraped off by the cleaning container 10 and the cleaning blade 10a counter-contacted with the surface of the photosensitive drum. Then, after being cleaned in this way, it waits for the next image formation.

  The above process is a case where a single color toner is used. However, in the case of a color printer using a plurality of color toners, a plurality of color toner images are developed on one photosensitive drum, or a plurality of color toners are used. A photosensitive drum is used.

  For color printer transfer, multiple transfer onto the intermediate transfer belt and then secondary transfer onto the recording material at once, or multiple transfer onto the recording material while adsorbing and transporting the recording material onto the transfer belt, etc. There are various methods for forming a toner image on a recording material.

  In any transfer method, in order to fix the toner image on the transferred recording material, printing is finally finished through a fixing device that pressurizes and heats the toner and fixes the toner image on the recording material. is there.

(Fixing device)
FIGS. 1A and 1B show a configuration of a halogen heater film heating type fixing device 12 as a fixing device according to the first embodiment of the present invention. In this halogen heater type film heating type fixing device, a fixing film 16 (thin metal film) as an endless belt which is a cylindrical fixing rotating body and a pressure as a pressure rotating body are used as members for forming a fixing nip portion. A roller 14 is provided. Then, a halogen heater 13a as a heating element, and a radiant light reflecting member 20 ′ provided for concentrating the radiant light of the halogen heater 13a on the fixing nip portion are provided. In addition, 17 'is an upper cover stay, 18' is a film guide stay, 19 'is a metal pressure stay for halogen heaters.

  Further, in the present embodiment, as shown in FIG. 1A, the extension portion of the metal plate 21 having the conventional configuration described in FIG. 5 is extended in the vertical direction (away from the recording material conveyance path) at the rear end of the fixing nip portion. It is replaced with a heated metal plate 23 bent in the direction). The heated metal plate 23 is slidably disposed on the inner peripheral surface of the fixing film 16 inside the fixing film 16 corresponding to the fixing nip portion, and receives radiant heat from the halogen heater 13a.

  The extension portion of the metal plate 23 to be heated is provided with a contact thermistor 22 and a thermo switch 22a that contact the extension portion of the metal plate 23 to be heated as temperature detecting means. It is arranged horizontally on the opposite side of the nip. Here, the contact type thermistor 22 and the thermo switch 22a are each opened in the film guide stay 18 ′ by two pieces, one piece in the longitudinal direction of the heated metal plate 23 (direction perpendicular to the recording material conveyance direction). It abuts on the metal plate 23 to be heated through two abutting square holes.

  The metal plate 23 to be heated is made of stainless steel, and the shape of the metal plate 23 to be heated in the longitudinal direction (direction perpendicular to the recording material conveyance direction) is shown in FIG. That is, in order to provide a plurality of temperature detection means in a direction orthogonal to the recording material conveyance direction, in this embodiment, three temperature sensor contact portions 23b for two thermistors and one thermoswitch are provided on the metal plate 23 to be heated. Provided as an extension. Thus, the metal plate 23 to be heated is bent and extended in the vertical direction with respect to the plane constituting the fixing nip portion in the minimum necessary range.

  In the present embodiment, the metal plate to be heated 21 has the following function as well as the function of holding the temperature detection element described above. In other words, the function of heating by receiving radiation light reflected by the reflecting member 20 and the fixed pressure member that forms the fixing nip portion while sliding with the fixing film 16 that rotates and moves between the pressure roller 14. It also has the function as In the present embodiment, a black coating layer 21a is formed on the heater-side surface of the metal plate 21 to be heated to enhance the absorption of radiation light.

In this embodiment, the changes of the peripheral members accompanying the replacement with the heated metal plate 23 are listed below.
(1) Arrangement of the halogen heater 13a on the fixing nip side (2) Reduction of the height of the pressurizing metal stay 19 '(about 30%)
(3) Height reduction of the radiant light reflecting member 20 '(about 30%)
(4) Horizontal arrangement of each temperature sensor and its pressure spring in the upper part of the pressurizing metal stay 19 '(5) Modification of the internal structure of the upper cover stay 17' and the film guide stay 18 'In this embodiment, The replacement with the heated metal plate 23 has the following effects. First, regarding the design circular orbit of the fixing film 16 that is assumed to rotate in contact with the film guide stay 18 ′, it can have a symmetrical shape (including a substantially symmetrical shape) with respect to the center of the fixing nip portion. For this reason, it is possible to suppress the occurrence of jamming around the discharge of the pressure roller due to contamination of the pressure roller when used for a long time with the conventional configuration. That is, it is possible to form a separation angle for separating the paper discharge front end portion upward on the fixing upper unit side downstream of the fixing nip portion.

  Further, the outer diameter (diameter) size of the fixing film 12 which has been conventionally 33 mm can be reduced to 25 mm, and the cost reduction can be promoted by improving the heating efficiency and reducing the amount of materials used for the fixing film. Furthermore, the volume of the upper cover stay 17 'and the film guide stay 18' on the downstream side of the fixing nip is reduced by about 50%.

  In addition, it demonstrates below whether the disadvantage accompanying the said change arises. In the present embodiment, since there is an extended portion (from the rear end (exit) of the fixing nip portion to the temperature detecting portion) in the metal plate 23 to be heated, a delay until the same temperature detection is conceivable with respect to the conventional configuration. However, in the configuration in which the detection is performed by at least a contact-type temperature sensor having a relatively high heat capacity, there is no particular problem in terms of temperature control of the actual machine even if the length of the metal plate having good heat conduction is extended by about 10 mm.

  In addition, heat leak due to contact between the metal plate of the routing extension part and another member can be considered, but in the configuration of the present embodiment, since the heat leak path is increased without increasing, the conventional configuration and Temperature detection without much difference is possible. That is, in the present embodiment, the metal plate 23 to be heated after being bent in the vertical direction at the rear end portion of the fixing nip portion is a film guide for supporting the metal plate end portion in the reflection member and the temperature detecting portion as in the conventional configuration. No contact portion is provided other than the minute protrusion provided in the inside.

  More specifically, since the metal plate 23 to be heated is extended to the temperature detection unit through a cavity provided inside the film guide stay, it is configured to be adiabatic without increasing the number of heat leak paths.

  Characteristics of the performance of the fixing device according to this embodiment include the following.

  (1) Since a fixing film having a lower heat capacity than that of the fixing roller of the heat roller type fixing device can be used, the start-up time of the fixing device can be shortened.

  (2) For a conventional film heating type fixing device that directly heats only the nip portion with a ceramic heater, a metal member having a higher heat conductivity than a ceramic heater is generally used as a metal plate to be heated, although it depends on the type of ceramic. Can be used as For this reason, it is advantageous for the temperature rise at the end when small-size paper is passed.

  (3) Since the temperature detector can detect near the fixing nip and using the heat conduction of metal, the measurement accuracy is improved and the surface of the fixing roller is damaged like a roller surface contact type thermistor in the heat roller method. No stains occur. In addition, since the temperature of the metal plate to be heated can be directly detected, reliability can be increased.

<< Second Embodiment >>
FIG. 3A is an explanatory diagram of an arrangement configuration in a fixing device according to the second embodiment of the present invention, and FIG. 3B is a perspective view of a metal plate to be heated according to the second embodiment. In the present embodiment, the shape of the metal plate 23 to be heated in the first embodiment is further changed, and the metal plate 24 to be heated is used which is bent and extended obliquely from the rear end of the fixing nip portion. The shape and the arrangement of the temperature sensor are changed according to this shape.

  In this embodiment, the extension part of the metal plate 24 to be heated is provided with a contact thermistor 22 and a thermo switch 22a that contact the extension part of the metal plate 24 to be heated as temperature detection means. It is arranged on the upper side. Specifically, a thermistor 22 and a thermo switch 22 ′ as temperature detecting units are obliquely installed on the slope of the metal pressure stay 19.

The metal plate 24 to be heated is made of stainless steel, and the shape of the metal plate 24 to be heated in the longitudinal direction (direction perpendicular to the recording material conveyance direction) is shown in FIG. In this embodiment, the metal plate 24 to be heated is arranged so that two thermistors 22 and one thermo switch 22a as temperature detecting portions are obliquely above the plane of the fixing nip portion in the longitudinal direction.
An extension is provided. That is, as the extended portion of the metal plate 24 to be heated, the three contact portions 24b of the temperature detecting portion are provided by being bent obliquely upward with respect to the plane constituting the fixing nip portion within the minimum necessary range. Yes.

  In this embodiment, the length of the extended portion (heated metal plate) from the rear end (exit) of the fixing nip portion to the temperature detection portion is shorter than that of the first embodiment (as compared to the detection portion of the conventional configuration). This is to avoid the possibility of delay until the same temperature is detected. In particular, the temperature detection responsiveness when the apparatus is further accelerated can maintain substantially the same performance as the conventional configuration. And while suppressing the occurrence of jamming around the pressure roller of the recording paper as the recording material after fixing, heating efficiency is improved and costs are reduced by reducing the amount of materials used for fixing films, etc. as the fixing device becomes smaller and lighter Promotion becomes possible.

<< Third Embodiment >>
4A is an explanatory diagram of an arrangement configuration in a fixing device according to a third embodiment of the present invention, FIG. 4B is an explanatory diagram of a non-contact arrangement of a temperature detection unit, and FIG. 4C is a perspective view of a metal plate to be heated. FIG. In the present embodiment, a part of the extension of the metal plate 24 to be heated in the second embodiment is replaced with a graphite sheet 25 having a higher thermal conductivity than the metal, and the temperature detection unit is disposed in a non-contact manner. It is characterized by that. That is, in the present embodiment, a non-contact temperature detection system that is not easily affected by the high temperature detection response in the graphite sheet 25 and the extra heat capacity is used. The same reference numerals as those in the second embodiment are omitted to indicate the same members.

  The graphite sheet 25 in this embodiment has a thickness of 75 μm, and has a thermal conductivity that is one digit higher than that of a conventional heated metal plate that uses stainless steel, and a heat capacity that is one digit lower. Then, in order to increase the degree of adhesion with the graphite sheet 25, the upper surface of the rear end of the metal plate 18 ″ a to be heated is polished to increase the smoothness, and the back surface of the sheet guide is placed on the opposing film guide 17 The bonded graphite sheet 25 is brought into pressure contact from above.

  Here, as shown in FIG. 4B, the graphite sheet 25 having the end closely attached to the heated metal plate 18 ″ a has the surface (temperature) as it is in contact with the heated metal plate 18 ″ a. It is drawn to a non-contact thermistor 27 and a surface facing the thermo switch 27 ′ as the detection unit. This effectively utilizes the thermal conductivity characteristic that the surface thermal conductivity of the graphite sheet 25 is much higher than the volume thermal conductivity in the thickness direction of the graphite sheet 25.

  Further, in FIG. 4B, on the surface of the film guide member 17, there are two locations, a region where the graphite sheet 25 rises vertically from the contact surface with the metal plate 18 ″ a and a temperature detection target region. A gap 26 is provided in Thereby, the contact between the back surface of the graphite sheet 25 and the film guide member 17 is prevented. Thereby, it is the structure which can avoid the addition of the extra heat capacity to the graphite sheet 25, and the addition of a heat leak path | route.

  In this way, the surface temperature of the graphite sheet 25 approaches the temperature of the fixing nip portion, and the response to the change can be dramatically improved over the conventional metal plate.

  In the present embodiment, the non-contact thermistor 27 and the thermo switch 27 ′ as temperature detecting units are obliquely installed on the slope of the metal pressure stay 19 as in the second embodiment. Unlike the conventional contact type thermistor 22 and the thermo switch 22 ′ shown in the first and second embodiments, since it is a non-contact type, it is less susceptible to the influence of an extra heat capacity.

  As described above, according to the present embodiment, the temperature change at the fixing nip portion can be transmitted to the temperature detection unit at a higher speed, and a higher temperature detection response can be obtained, which can be applied to a further high-speed printing apparatus. Even in such a high-speed device, the occurrence of jamming around the pressure roller for discharging the paper is suppressed, and the heating efficiency is improved and the cost is reduced by reducing the amount of material used for the fixing film, etc., as the fixing device is reduced in size and weight. Down promotion is possible.

(Modification)
In the above-described embodiment, the preferred embodiment of the present invention has been described. However, the present invention is not limited to this, and various modifications can be made within the scope of the present invention.

(Modification 1)
In the embodiment described above, the endless belt is provided on the first rotating body (fixing rotating body). However, the endless belt is opposed to the second rotating body (facing the first rotating body and the first rotating body together with the fixing nip). May be provided on a rotating body forming the portion. An endless belt may be provided on both the first rotating body and the second rotating body.

(Modification 2)
In the above-described embodiment, the case where the first rotating body (fixing rotating body) and the pressurizing rotating body as the pressurizing body pressurize the fixing rotating body has been described. However, the present invention is not limited to this, and can be similarly applied to a case where a rotating body as an opposing body is pressed from an endless belt as a fixing rotating body, not as a pressing body. Here, the opposing body is a member that faces the fixing rotator, presses against the fixing rotator, forms a fixing nip portion, and clamps the moving recording material at the fixing nip portion.

(Modification 3)
In the above-described embodiment, the pressure rotating body (pressure roller) that rotates together with the fixing rotating body is shown as the pressure body. However, the present invention is not limited to this, and a flat plate-shaped pressure body fixed as the pressure body. A pad can also be applied.

(Modification 4)
In the embodiment described above, the recording paper has been described as the recording material. However, the recording material in the present invention is not limited to paper. Generally, a recording material is a sheet-like member on which a toner image is formed by an image forming apparatus. For example, regular or irregular plain paper, cardboard, thin paper, envelope, postcard, seal, resin sheet, OHP sheet, Includes glossy paper. In the above-described embodiment, for the sake of convenience, the recording material (sheet) P has been described using terms such as passing paper, discharging, paper feeding, paper passing portion, and non-paper passing portion. The recording material is not limited to paper.

(Modification 5)
In the above-described embodiment, the fixing device that fixes an unfixed toner image to a sheet has been described as an example. However, the present invention is not limited to this, and the toner image that is supposedly attached to the sheet is used to improve the gloss of the image. The present invention can be similarly applied to a device for heating and pressing (also called a fixing device in this case).

14 .... Pressure roller, 16 .... Fixing film, 22 .... Thermistor, 22a ... Thermo switch, 23 ... Metal plate to be heated

Claims (10)

A cylindrical rotating body;
An opposing body that forms a fixing nip portion that faces the cylindrical rotating body and fixes a toner image on a recording material together with the cylindrical rotating body;
A metal plate to be heated that slides with the inner peripheral surface of the cylindrical rotating body inside the cylindrical rotating body corresponding to the fixing nip portion and receives radiant heat from the heating element;
A fixing device comprising:
Bending the heated metal plate in the direction away from the recording material conveyance path at the rear end portion in the recording material conveyance direction of the fixing nip,
A fixing device, characterized in that a temperature detecting means is provided on the bent extension portion or facing the extension portion. A metal pressure stay that pressurizes the heated metal plate;
A reflection member provided between the metal pressure stay and the heating element and between the metal pressure stay and the heated metal plate, and reflecting the radiation light from the heating element;
A guide member for guiding the cylindrical rotating body to the fixing nip portion;
The fixing device according to claim 1, further comprising: Bending the rear end of the heated metal plate at the rear end of the fixing nip,
The fixing device according to claim 2, wherein the temperature detection unit that contacts the bent extension portion is provided in a horizontal direction. Bending the rear end of the heated metal plate at the rear end of the fixing nip,
The fixing device according to claim 2, wherein the temperature detection unit that contacts the bent extension portion is provided in an oblique direction. Bending the rear end of the heated metal plate at the rear end of the fixing nip,
The fixing device according to claim 1, wherein a graphite sheet is provided in the bent extension portion, and the temperature detecting unit is provided in a non-contact manner so as to face the graphite sheet.   6. The fixing device according to claim 3, wherein the temperature detecting unit is in contact with the metal pressure stay.   The fixing device according to claim 1, wherein the metal plate to be heated 24 is made of stainless steel.   The fixing device according to claim 1, wherein the cylindrical rotating body is an endless belt.   The fixing device according to claim 1, wherein the opposing body is a pressure roller.   The fixing device according to claim 1, wherein a plurality of the temperature detection units are provided in a direction orthogonal to the recording material conveyance direction.