JP6679336B2 - Image heating device and image forming device - Google Patents

Description

  The present invention relates to a film heating type image heating apparatus for heating a developer image on a recording material and an image forming apparatus including the image heating apparatus.

A conventional film heating type image heating apparatus of this type generally has a contact heating type configuration in which a fixing nip is formed between a heat roller and a pressure roller while a ceramic heater is in contact with the inner surface of the heat resistant film. ing. On the other hand, in recent years, as described in Patent Document 1, a film heating type fixing device (image heating device) in which a heater portion is composed of a radiant heating element such as a halogen heater has begun to be commercialized.
The fixing device described in Patent Document 1 is arranged so as to be in sliding contact with a flexible film-shaped tubular member, a halogen heater disposed inside the tubular member, and an inner peripheral surface of the tubular member. And a heated plate made of metal. The heated plate is configured to be heated by receiving radiant heat from the halogen heater, and further includes a reflecting member that reflects the radiant heat of the halogen heater toward the heated member. Then, by sandwiching the tubular member between the heated plate heated by the halogen heater and the pressing member, a fixing nip is formed between the heating member and the pressing member.
In this way, a heated plate is placed in the fixing nip so as to replace the function of the conventional ceramic heater, and the halogen heater centrally heats this in a non-contact manner to obtain a fixing device with the same high startup performance. There is.

However, the fixing device described in Patent Document 1 does not take sufficient measures against so-called edge temperature rise that occurs when a small-sized recording material is continuously fed.
That is, conventionally, since the halogen heater heats the entire length in the longitudinal direction of the heated plate in accordance with the recording material of the maximum size, when the recording material of a small size is passed, heat is not generated in the passing portion of the recording material. The temperature drops because it is taken away by the recording material.
On the other hand, in the non-sheet passing area at the end where the recording material does not pass, the temperature does not easily decrease and the temperature rises. Since the plate to be heated is a metal plate, if a metal material having a high thermal conductivity is used, heat from the non-paper-passing region of the plate to be heated easily moves, and the temperature rise at the edges is reduced. There is a limit in heat conduction alone. In practice, the material to be heated is a stainless steel plate having a lower thermal conductivity than alumina (thermal conductivity = about 30 W / mk), which is a typical substrate material for ceramic heaters, in consideration of cost and durability. (Thermal conductivity = about 20 W / mk) is adopted.
Therefore, it is conceivable to use two heaters, which are designed so that the light distribution ratios are different between the central portion and the end portion, as the halogen heaters and control the lighting ratio of each heater to obtain the end portion temperature rise suppression effect. .
However, if two heaters are used, there is a problem that the size becomes large and the cost also increases.

On the other hand, Patent Document 2 describes a technique of providing a rotary light shielding member around one halogen heater in a heat roller fixing device as a measure against the temperature rise at the end portion during small size fixing.
That is, a rotation light shielding member that covers the heater is provided inside the heating roll, and the exposure width in the longitudinal direction of the heater (direction orthogonal to the sheet passing direction) is switched according to the paper size.
Inside the heating roll, a fixed sleeve having a slit that regulates the exposure width of the recording material in the transport direction so as to surround the halogen heater is arranged, and a rotary light shielding member is arranged inside the fixed sleeve. The rotation shading member is adapted to adjust the axial length of light emitted from the halogen heater to the slit of the fixed sleeve by rotation. The rotation shading member has a cylindrical shape and is provided with a cutout portion for emitting light toward the slit, and the cutout portion gradually changes the axial length of the light emitted to the slit along with the rotation. Is cut out like. Then, the irradiation area is adjusted according to the paper width size, and the end area, which is the non-sheet passing area, is shielded.
However, in Patent Document 2, since the halogen heater is located at the rotation center of the rotary light shielding member, and the fixed sleeve is interposed between the halogen heater and the inner surface of the heating roll, the inner surface of the heating roll irradiated by the radiant light is reached. The gap becomes larger. Therefore, there is a problem that radiant light leakage from the end portion in the longitudinal direction, which should be restricted according to the paper width, is significant, and the effect of suppressing the end portion temperature rise cannot be sufficiently exerted.

JP, 2012-212066, A JP, 2006-267420, A

  An object of the present invention is to provide a film heating type image heating apparatus composed of a radiant heating element, which can effectively prevent an edge temperature rise when a narrow recording material is continuously fed. An object is to provide an image forming apparatus.

The present invention is to achieve the above object,
A rotatable cylindrical member having flexibility, and radiant heating element arranged in the internal space of the tubular member, the tubular member is an inner peripheral surface and sliding freely disposed of, from the radiant heating element A heated plate that is heated by receiving the radiant heat of the radiant heat, and a reflecting member that is disposed in the internal space of the tubular member and that reflects the radiant heat of the radiant heating element toward the heated plate. A heating unit including a reflecting member having a cross-sectional shape of which the plate side is open ,
A pressing member that forms a fixing nip that pressurizes and heats the recording material between the tubular member by sandwiching the tubular member with the heated plate,
And an image heating device for heating a toner image formed on a recording material ,
A light blocking member rotatable around the radiant heating element is provided in the internal space of the tubular member, and the light blocking member has a cylindrical rotation locus and has a width of a plurality of recording materials. Corresponding plural openings are formed in the rotation direction, and the opening corresponding to the width of the recording material is made to face the heated plate by rotating the light shielding member,
The radiation heating element is eccentric in the direction of the heated plate with respect to the rotation center position of the light shielding member,
The reflecting member is located in an internal space of the light shielding member and in a space outside the light shielding member, and is a portion that forms the opening. An upstream side reflection part and a downstream side reflection part respectively extending toward the upstream side and the downstream side of the fixing nip,
At a position between the main body reflection part and the upstream side reflection part of the reflection member and a position between the main body reflection part and the downstream side reflection part, in the passage area that is applied to the rotation trajectory of the light shielding member, A slit portion is provided through which the light blocking member can pass,
The light shielding member is configured to rotate through the slit portion .
The image forming apparatus of the present invention is characterized an image forming section for forming a toner image on a recording material, further comprising an image heating apparatus described above.

  As described above, according to the present invention, in the film heating type image heating apparatus including the radiant heating element such as the halogen heater, the edge temperature rise when the narrow recording material is continuously fed is performed. It can be effectively prevented.

(A) is a cross-sectional view of the fixing device (image heating device) according to the first embodiment of the present invention, (B) is a perspective view of the rotary shutter of (A), and (C) is a perspective view of the reflection plate of (A). , (D) is an exploded perspective view of a main part. The graph which shows the experimental result which confirmed the effect of a rotating shutter. FIG. 1 is a diagram showing a configuration example of an image forming apparatus to which a fixing device of the present invention is applied. (A) is a cross-sectional view of the film unit of the fixing device according to the second exemplary embodiment of the present invention, (B) is a perspective view of an integral reflection member, (C) is a perspective view of a rotary shutter, and (D) is reflection. FIG. 6 is a perspective view of a state in which a member and a rotary shutter are combined. (A) is a cross-sectional view of a film unit of a fixing device according to Embodiment 3 of the present invention, (B) is an enlarged cross-sectional view of a halogen heater with a reflection coating layer, (C) is a perspective view of the halogen heater of (B). Fig. (A) is a cross-sectional view of a film unit of a fixing device according to Embodiment 4 of the present invention, (B) is an enlarged cross-sectional view of a halogen heater with a reflection coating layer, (C) is a perspective view of the halogen heater of (B). Fig.

Embodiments of an image heating apparatus according to the present invention and an image forming apparatus including the same will be described below in detail with reference to the accompanying drawings.
[Embodiment 1]
An image forming apparatus to which the present invention is applied is an apparatus having an image forming unit that forms a toner image as a developer image on a recording material, and includes an electrophotographic printer, a copying machine, a facsimile, and the like. . In the present embodiment, in the image forming unit, a toner is used as a developer, a toner image is formed on a recording material by an electrostatic image forming unit, and the toner image formed on the recording material is an image heating device. It is melted and fixed by.
FIG. 3 shows a basic configuration of an electrophotographic monochrome printer as a basic example of the image forming apparatus.
That is, in the image forming section, after the surface of the photosensitive drum 2 is uniformly charged by the charging roller 1 to a predetermined polarity, only the area where the photosensitive drum 2 is exposed by the exposing section 3 such as a laser is discharged to remove the photosensitive drum. 2. Form a latent image on 2.
This latent image is visualized as a toner image by the developing device 4. That is, the toner 5 is triboelectrically charged between the developing blade 4a and the developing sleeve 4b in the same polarity as the surface of the photosensitive drum 2. The triboelectrically charged toner 5 is conveyed to a portion where the photosensitive drum 2 and the developing sleeve 4b face each other, and is floatingly vibrated by the electric field action by the superimposed application of the DC and AC biases to adhere to the latent image on the photosensitive drum 2 to be developed. To be done.
The toner image formed by selectively adhering to the photosensitive drum 2 is conveyed to the transfer nip formed by the transfer roller 6 and the photosensitive drum 2 by the rotation of the photosensitive drum 2.
As the developing method up to this point, in addition to the above-mentioned non-contact method, a DC bias is applied while the elastic developing roller is in contact with the photosensitive drum to selectively attach the toner to the latent image forming portion of the photosensitive drum. There are also development 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 transport roller pair 7d by the paper feed roller pair 7c, and then before transfer by the vertical transport roller pair. It is conveyed to the conveying roller 7e. Further, the recording material is conveyed by the pre-transfer conveying roller 7e to the transfer nip along the transfer guide plate 9 at a predetermined approach angle. During the conveyance, the charge eliminating brush 8 contacts the back side of the recording material to eliminate unnecessary charges on the surface of the recording material, and then to the transfer nip.
At the transfer nip, in order to electrostatically attract the toner on the photosensitive drum 2 and move it to the recording material side, a high voltage having a polarity opposite to that of the toner is applied to the transfer roller 6 on the back surface of the recording material. At the same time, in order to keep the toner on the recording material, a transfer charge having a polarity opposite to that of the toner is applied to the back surface of the recording material.
Finally, the recording material 7 to which the toner image is transferred is conveyed to the fixing nip of the fixing device 12 including the film unit 13 as the heating rotator and the pressure roller 14.
In the fixing nip, a toner image is formed by heating and pressurizing while keeping constant temperature control by a constant temperature control means (not shown) provided on the film unit 13 side as a heating rotator so as to maintain a preset fixing temperature. It is fixed.
Since a small amount of adhering matter such as toner having different polarities remains on the surface of the photosensitive drum 2 after the transfer of the toner image, the adhering matter is removed by the cleaning blade 10a on the surface of the photosensitive drum 2 after passing through the transfer nip. The cleaning blade 10a is counter-contacted with the surface of the photosensitive drum 2 so as to oppose the rotational direction, and the scraped-off toner and the like is collected in the container 10 and waits for the next image formation.

The above steps are for the case of using a single color toner, but 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, and the number of colors of the color toners is the same. A plurality of photosensitive drums are used.
In the case of a color printer, there are various transfer methods in the process of forming a toner image on a recording material. As the transfer method, a method in which multiple transfer is performed on the intermediate transfer belt and then secondary transfer is collectively performed on the recording material, a method in which multiple transfer is performed on the recording material while suction-conveying the recording material on the transfer belt, and the like are applied. It
In any of the transfer methods, in order to permanently fix the transferred toner image on the recording material, the printing is finally finished via the fixing device 12 that pressurizes and heats the toner to permanently fix the toner on the recording material. Are common.

<Fixing device>
Next, the fixing device will be described in detail with reference to FIG.
1A is a sectional view of a fixing device, FIG. 1B is a perspective view of a rotary shutter, and FIG. 1C is a perspective view of a reflection plate.
The fixing device 12 includes a film unit 13 as a heating rotator and a pressure roller 14 as a pressure member that contacts the film unit 13 to form the fixing nip N.
The film unit 13 includes a fixing film 16 as a rotatable cylindrical member having flexibility, and a single rod-shaped halogen heater 13a as a radiant heating element arranged inside the fixing film 16. There is. Further, the heated plate 21 that is slidably arranged on the inner peripheral surface of the fixing film 16 and is heated by receiving the radiant heat from the halogen heater 13a, and the reflection that reflects the radiant heat of the halogen heater 13a toward the heated plate 21. And a reflecting member 25 as a means. The pressure roller 14 forms a fixing nip N with the fixing film 16 by sandwiching the fixing film 16 with the heated plate 21.
Although not particularly shown, the fixing film 16 has a laminated film structure such as a two-layer structure including a base layer and a release layer, or a three-layer structure including an elastic layer provided between the base layer and the release layer. The base layer is composed of a heat-resistant resin film such as polyimide or a film-like thin metal layer having high thermal conductivity. The release layer is a surface layer portion of the film and is formed of PFA or PTFE having a good release property. Silicone rubber or the like is used as the elastic layer.

Inside the fixing film 16, a film guide 18 for guiding the fixing film 16 is provided, and inside the film guide 18, for uniformly pressing the fixing nip N between the heated plate 21 and the pressure roller. A pressure stay 19 made of metal is arranged. Further, an upper cover stay 17 is provided to prevent contact between the fixing member 16 and the wiring member of the internal electric component.
The pressure stay 19 is a long member having an inverted U-shaped cross-section with the heated plate 21 side open, and the halogen heater 13a, the rotary shutter 26, and the reflection member 25 are arranged in the internal space, and the lower end open portion is closed. Thus, the heated plate 21 is assembled.
The reflecting member 25 is arranged to concentrate the radiant light of the halogen heater 13a on the fixing nip N.
The heated plate 21 is a plate-shaped member that extends in a direction orthogonal to the sheet passing direction, and extends in parallel with the halogen heater 13a. The heated plate 21 has a function of receiving the radiant light reflected by the reflection member 25 to heat up and heat it, and forms a fixing nip N while sliding on the fixing film 16 which rotates and moves with the pressure roller 14. It also has a function as a fixed pressure member. A black coating layer 21 a for enhancing absorption of radiant light is formed on the heater side surface of the heated plate 21.

In the illustrated example, the recording material P is conveyed from the right side toward the paper surface, passes through the fixing nip N, and is discharged to the left side of the paper surface. However, the film unit 13 has a recording material passing direction. The shape is such that it extends significantly beyond the nip width toward the downstream side. As a result, the area in which the fixing film 16 is transported horizontally before and after the fixing nip N is longer than in the conventional example.
An extension piece 21c that partially extends toward the downstream side in the sheet passing direction is provided at an edge of the heated plate 21 on the downstream side in the sheet passing direction (recording material conveying direction), and the thermistor contacts the extension piece 21c. 22 are arranged. The thermistor 22 is inserted into a hole provided in the film guide 18, and is pressed against the extension piece 21c by an upper pressing spring 22a and an upper cover stay 17 screwed to the film guide 18.
That is, a temperature detection unit by the thermistor 22 is provided at the downstream side of the fixing nip N of the heated plate 21 in the sheet passing direction, and by utilizing the thermal conductivity of the metallic heated plate 21, a temperature close to the temperature of the fixing nip N is obtained. Is configured to be detected. In order to secure the space of the temperature detecting portion, the film unit 13 is extended to the fixing nip N on the downstream side longer than the upstream side in the sheet passing direction.
FIG. 1D is an exploded perspective view of main fixing components for easy understanding of the shapes and arrangements of these respective components.
Thermoswitches 22b are provided on both sides in the longitudinal direction of the thermistor 22 arranged in the central fixing portion. In order to secure the contact position of the thermo switch 22b, the thermo switch is provided at the edge of the heated plate 21 on the downstream side in the sheet passing direction (recording material conveying direction), like the extension piece 21c with which the thermistor 22 contacts. An extension piece 21b serving as a seating surface of 22b is partially projected. The temperature sensors such as the thermistor 22 and the thermoswitch 22b are held in three rectangular holding holes 18a formed in the film guide 18.
On the other hand, the pressure roller 14 as a pressure rotator has an elastic layer 14b made of heat resistant rubber or the like on a pressure metal core 14c having a rotating shaft 14d, and a pressure side release layer 14a on the surface thereof. It is configured to have.

-Structure of the rotary shutter 26 As shown in FIG. 1B, the rotary shutter 26 is a thin-walled cylindrical body made of metal and has a rotation locus in a cylindrical shape along the circumference. A plurality of openings 26a to 26d corresponding to the widths of a plurality of sizes of recording materials used are provided. The width of the recording material is the width in the direction orthogonal to the conveying direction of the recording material. The openings 26a to 26d are provided in order in the rotation direction of the rotary shutter 26, and by rotating the rotary shutter 26, the openings corresponding to the width of the recording material P are formed on the heated plate 21 forming the fixing nip N. It is configured to face each other.
Specifically, it is composed of an aluminum cylinder having a thickness of 0.5 mm. The openings 26a to 26d are provided in accordance with the respective four paper widths for the LTR size, the B5 size, the A5 size, and the COM10 envelope size.
The exposure width of the radiant light is variable according to the width of the recording material by the openings 26a to 26d, and the region from the longitudinal ends of the openings 26a to 26d to the longitudinal ends of the rotary shutter 26 is shielded. It becomes an area.
Further, the width of each of the openings 26a to 26d in the sheet passing direction is substantially the same as the width of the fixing nip N in the sheet passing direction (there is a slight difference because of the curvature).
The rotation center position of the rotary shutter 26 is eccentric with respect to the halogen heater 13a in the direction opposite to the heated plate 21, and the lowermost surface of the halogen heater 13a and the rotary shutter 26 facing the fixing nip is covered. It is arranged on the back surface of the heating plate 21 as close as possible.
That is, the halogen heater 13a, the rotary shutter 26, and the heated plate 21 are arranged so that the gap between the members is minimized. The minimum meaning means, for example, a state in which other members are so close to each other that they cannot be arranged between them.
From this, the minimum value of the diameter of the rotary shutter 26 is naturally determined by defining the width of the partition 26e between the openings 26a to 26d. In particular, unless otherwise impeded, the rotary shutter 26 is constructed with a diameter close to this minimum. Specifically, for example, the rotary shutter 26 having a diameter of about 16.5 mm is used.

-Structure of Reflecting Member 25 The reflecting member 25 has an open box cross-sectional shape that surrounds the halogen heater 13a and opens on the side of the plate to be heated. It almost matches the width. Further, the positions of the opening 25 e of the reflecting member 25 and the opening of the rotary shutter 26 facing the heated plate 21 are located at substantially the same position with respect to the heated plate 21.
The reflecting member 25 is divided into three parts: a main body reflecting portion 25c arranged inside the rotary shutter 26, an upstream reflecting portion 25a arranged outside the rotating shutter 26, and a downstream downstream reflecting portion 25b. It has a divided structure.
The main body reflecting portion 25c is arranged inside the rotating shutter 26, and the upstream reflecting portion 25a and the downstream downstream reflecting portion 25b are outside the rotating shutter 26 and upstream with respect to the fixing nip N in the sheet passing direction. Side and downstream.
Then, the rotary shutter 26 is configured to rotate through the gaps g between the body reflecting portion 25c and the upstream reflecting portion 25a and between the body reflecting portion 25c and the downstream reflecting portion 25b.

The main body reflecting portion 25c of the reflecting member 25 has a U-shaped cross section having an arcuate portion that matches the curvature of the halogen heater 13a. The arcuate portion is as close as possible to the halogen heater 13a, and together with the halogen heater 13a, the longitudinal end portion. Held in. Further, both legs are arranged so as to be close to the rotation surface of the rotary shutter 26 while avoiding the rotation trajectory of the rotary shutter.
The upstream reflection portion 25a and the downstream reflection portion 25b prevent the radiation light from leaking from the front and rear direction of the fixing nip N at the lower surface opening of the main body reflecting portion 25c and guide the light toward the fixing nip N side.
The upstream-side reflection portion 25a is configured by a plate-shaped reflection piece that extends like a flange toward the upstream side in the sheet passing direction, with the end portion separated by the gap g from the lower end of the upstream-side leg portion of the main body reflection portion 25c as the downstream end. To be done.
In addition, the downstream reflection portion 25b and a reflection piece 25b1 extending toward the heated plate 21 in a state of being offset to the downstream side with a gap between the lower end of the leg portion on the downstream side of the main body reflection portion 25c and the reflection piece 25b1. The flange 25b2 is bent from the lower end of the piece 25b1 and extends in the downstream direction in the sheet passing direction.
The flanges 25b2 of the upstream reflection portion 25a and the downstream reflection portion 25b are held so as to be sandwiched between the end portion of the heated plate 21 and the lower end of the pressure stay 19, respectively. The upstream reflecting portion 25a may be configured by extending the end of the heated plate 21 in the sheet passing direction. Also in this case, the reflecting member 25 is divided into three parts.

With the above-described configuration, in this fixing device, at least four types of exposure widths in the longitudinal direction are rotated / stopped by a predetermined amount using a rotation driving unit (not shown) in accordance with the width of the paper size to be used. It becomes possible to switch. In particular, since the longitudinal direction can be regulated very close to the rear surface of the fixing nip N, it is possible to effectively suppress the temperature rise of the end portion while minimizing the leakage of radiant light to the surroundings. .
Further, with the above configuration, the reflection surface of the reflection member 25 can be reduced to a necessary minimum, and heating loss due to extra heating or heat transfer can be minimized, so that heating efficiency is also improved.
FIG. 2 shows an experiment in which small-size paper is continuously fed so as to raise the edge portion temperature so that the fixing film temperature rises to near 250 ° C. in order to verify the effect of the edge portion temperature rising countermeasure. 6 is a graph of a temperature rise experiment in which the rotary shutter 26 was cut at the center in the longitudinal direction and used, and the end portion temperature rise countermeasure effect was applied only to the right half side. That is, in order to make it possible to more accurately compare the countermeasure effects of the present invention under the same conditions, the rotary shutter 26 does not act on the left half surface in the longitudinal direction, and the rotary shutter 26 acts only on the right half surface. Longitudinal temperature at the center height intermediate between the fixing nip part and the fixing film apex part of the fixing film unit after the rotary shutter 26 is set to the COM10 envelope regulating position and 10 sheets of the COM10 envelope are continuously fed at full speed. The distribution was measured.
As can be seen from this graph, the end half-side temperature rise of the left half surface where the rotary shutter 26 did not act even though the temperature was adjusted at 170 ° C., the same experiment was performed with the conventional configuration after passing 10 COM10 envelopes. By repeating the result obtained, the temperature was raised to 250 ° C, which is higher by about 80 ° C. On the other hand, on the right half surface where the rotary shutter 26 is acted, almost no temperature rise is observed at the end portion, and an epoch-making effect of being able to suppress the temperature by about 80 ° C. is obtained as compared with the conventional case where the temperature control temperature is maintained as it is. You can see that

Next, Embodiments 2 to 4 of the present invention will be described.
In the following description, the points that are different from the first embodiment will be mainly described, and the same components will be denoted by the same reference numerals and the description thereof will be omitted.
[Embodiment 2]
FIG. 4 shows a film unit of the fixing device according to the second exemplary embodiment of the present invention, a reflecting member thereof, and a rotary shutter.
In the first embodiment, the reflecting member 25 is divided into the inside of the rotary shutter 26 and the member arranged outside thereof, but in the second embodiment, the reflecting member 25 is integrated. That is, a new integrated reflecting member 27 and a new rotary shutter 28 with sleeves on the left and right ends that allow the rotary shutter to pass back and forth through a partial area of the reflecting member 27 are used. A slit 27d that allows the rotary shutter 28 to pass therethrough is provided in a passage area of the rotary path 28.
That is, the reflecting member 27 includes a main body reflecting portion 27c arranged inside the rotary shutter 28, an upstream reflecting portion 27a arranged outside the rotating shutter 28, and a downstream downstream reflecting portion 27b. . The upstream reflection portion 27a and the downstream reflection portion 27b are arranged outside the rotary shutter 28 and on the upstream side and the downstream side with respect to the fixing nip N in the sheet passing direction.
Then, the rotary shutter 28 is configured to rotate through a slit portion 27d formed between the body reflecting portion 27c and the upstream reflecting portion 27a and between the body reflecting portion 27c and the downstream reflecting portion 27b. Has become.
That is, the main body reflecting portion 27c and the upstream reflecting portion 27a and the downstream reflecting portion 27b are integrally formed at both ends, and the slit portion 27d is provided only in the region of the rotary orbit of the rotary shutter 28. A certain reflecting member 27 is adopted. The length L0 of the slit portion 27d is shorter than the length of the reflecting member 27 itself in the longitudinal direction, is equal to or less than the maximum paper passing width, and is longer than the paper width of the length to be regulated next to the maximum paper passing width. It has an opening length.

On the other hand, along with this, the rotary shutter 28 is provided with a cylindrical imperfect cylindrical body 28c that is notched over the entire length in the longitudinal direction corresponding to the maximum sheet passing width. Further, bridge portions 28a as connecting portions extending along the longitudinal direction to the outside of the longitudinal end portions of the reflecting member 27 are provided at both left and right ends of the incomplete cylindrical body 28c in the longitudinal direction. Further, it has a configuration in which an annular drive connection portion 28b for receiving rotational drive is provided outside the bridge portion 28a.
The incomplete cylindrical body 28c has a cutout portion 28d cut out over the entire length corresponding to the maximum width of the recording material. That is, as compared with the rotary shutter 26 of the first embodiment, the length L1 between the end faces in the longitudinal direction of the incomplete cylindrical body 28c has an opening O1 for the maximum paper width in four places (here, an opening for LTR size). Is shorter than the longitudinal regulation position of. Further, the length is shortened to a position longer than the longitudinal regulation position of the paper having the length to be regulated next (here, the opening O2 for B5 size). As a result, the end face in the longitudinal direction of the imperfect cylindrical body has a D-cut shape. Similar to the first embodiment, the incomplete cylindrical body 28c is provided with three openings O2, O3, O4 in accordance with three paper widths for B5 size, A5 size, and COM10 envelope size. .
One of the two side edges along the longitudinal direction formed by this D-cut is directly inserted into the slit portions 27d, 27d of the reflecting member 27 of the integrated member and assembled to the reflecting member 27 (Fig. 4 (D)). Further, the other side edge of the cutout portion 28d is a bridge portion 28a which is as thin as possible within a range in which strength can be maintained, and is extended to the outside of the longitudinal end portion of the reflecting member 27. A ring-shaped drive connection portion 28b that is drivingly connected to a rotation drive portion (not shown) is provided at an end of the bridge portion 28a.
Thus, when fixing the paper having the maximum paper passing width, the rotary shutter 28 is not rotated in this state, and the plate to be heated 21 and the halogen heater 13a having the length in the longitudinal direction according to the LTR size are used as they are. Establish. When paper of B5 size or smaller is used, it is rotated to bring the openings O2, O3, O4 having an opening width corresponding to the paper width as close as possible to the fixing nip facing position.
As described above, according to the second embodiment, it is possible to obtain the same effect as that of the first embodiment while reducing the number of parts by integrating the reflecting member 27 and improving the assembling property.

[Third Embodiment]
FIG. 5 shows a film unit and a halogen heater of the fixing device according to the third embodiment of the present invention.
The present embodiment is intended to further reduce the size of an apparatus required for products having a slower printing speed, reduce the number of parts, and improve the assemblability to reduce costs.
At least a part of the reflecting means for reflecting the radiant light of the halogen heater 29 is configured by a reflective coating layer 29a coated on the surface of the halogen heater 29 opposite to the heated plate 21.
In the third embodiment, the reflection means deletes the reflection coating layer 29a and the reflection portion covering the upper half of the halogen heater of the reflection member having the slit of the second embodiment, and the upstream reflection portion 27a 'having the slit and the slit. And a downstream side reflection portion 27b '. In comparison with the second embodiment, the halogen heater itself is improved to use the halogen heater 29 with a reflection coat in which the reflection coat layer 29a made of ceramic with a thickness of about 0.2 mm is formed on the upper half surface of the glass tube on the non-fixing nip side. It is characterized by having been. The upstream reflection portion 27a 'and the downstream reflection portion 27b' are each provided with a slit portion 27d 'through which the rotary shutter 26 passes.

Due to this change, the entire fixing device is downsized, so that the halogen heater looks large relative to the entire film unit 13 even if the heater has the same size as in the first and second embodiments. There is.
By thus forming the reflection coat layer 29a on the surface of the glass tube of the halogen heater 29, there is a concern that the reflection efficiency may be deteriorated due to stains or discoloration of the reflection surface during long-term use when the reflection member is brought close to it. There is no need. Further, by eliminating the upper structure of the reflecting member in comparison with the second embodiment, it is possible to form the reflecting structure in a narrower space even if the same size heater is used, and it is possible to promote downsizing of the device. At the same time, the number of parts is reduced and the arrangement adjustment between the reflection member and the heater or the rotary shutter 26 is not necessary, so that the assembling property can be further simplified.

[Embodiment 4]
FIG. 6 shows a film unit and a halogen heater of the fixing device according to the fourth exemplary embodiment of the present invention.
In the fourth embodiment, the structure of the third embodiment is further developed, and as shown in FIG. 5A, the main body reflecting portion 25c inside the rotary shutter of the first embodiment is deleted, and the halogen heater is provided inside the rotary shutter 26. It is simplified to place only 30.
In order to realize this structure, the area where the reflective coat layer 30a made of ceramic is formed on the glass tube surface of the halogen heater is further extended from the upper half surface to the side surface portion, and the radiant light leaks in the lateral direction by the reflective plate inside the shutter. It has a configuration in which the suppression function is also used. That is, the reflection coating layer 30a is extended from the surface of the halogen heater 30 opposite to the heated plate 21 to the side surface on the upstream and downstream sides of the recording material in the transport direction, and the reflection means is constituted only by the reflection coating layer 30a. . Therefore, as the reflection means in the light blocking member, only the reflection coating layer 30a is provided in the rotary shutter 26.
Specifically, in the present embodiment, as can be seen from FIGS. 6B and 6C, the range of 120 ° with respect to the lower surface direction of the halogen heater 30 is narrowed down without exposing the exposure layer. There is. By arranging the halogen heater 30 close to the lower end of the rotary shutter 26, it is possible to selectively expose only the substantially same width as the opening of the rotary shutter 26 without a reflector.

  By using the above configuration, the area where there is concern about a decrease in reflection efficiency due to dirt or discoloration of the reflector surface during long-term use when the reflectors are brought close to each other is further reduced, and members other than the heater are installed inside the rotary shutter. You will not need to place it. Therefore, in order to suppress the interference of the member with the inner surface of the rotary shutter 26 and the leakage of the radiant light as in the second and third embodiments, the rotary shutter passage slit is kept as thin as possible while suppressing the rotary shutter passage slit. It is not necessary to adjust the configuration so that Therefore, it becomes possible to form the reflection structure of the radiated light more easily and in a narrower space, and it is possible to promote the miniaturization of the device, the reduction of the number of parts, and the drastic simplification of the assembling property.

In each of the above configurations, the rotary shutter shown in each drawing is provided with a partitioning frame between the openings provided for each paper width, but by adjusting the material and thickness so that the same strength can be maintained. It goes without saying that the partition may be eliminated and each opening may be formed in a staircase shape, and further, the longitudinal width of the opening may be cut out in a slanting linear shape along the circumference to distinguish between the respective paper widths. With a configuration that changes steplessly, the edge exposure regulation amount for each paper width is slightly reduced, but it is possible to suppress the edge temperature rise for a wider variety of paper width sizes.
In the above embodiment, the image heating device is applied to the fixing device that heats and presses the unfixed toner image formed on the recording material to fix it, but the image heating device is not limited to the fixing device. For example, it can be applied as a device for giving gloss to a toner image fixed on a recording material.

5 toner (developer), 7 recording material 12 fixing device (image heating device)
13 Film unit (heated rotating body)
14 pressure roller (pressure member),
13a Halogen heater (radiant heating element)
16 Fixing film (cylindrical body)
21 Heated Plate, 21a Black Paint Layer 25 Reflecting Member: First Embodiment
25a upstream reflection part, 25b downstream reflection part, 25c main body reflection part 25e opening 26 rotary shutter (light blocking member): Embodiment 1
26a-26d Opening part, 26e Partition part 27 Reflecting member (Embodiment 2)
27a upstream reflection part, 27b downstream reflection part, 27c main body reflection part 27d slit part 28 rotary shutter (second embodiment)
28a bridge part, 28b drive connection part, 28c incomplete cylindrical body,
28d Notch 29 Halogen heater (Embodiment 3), 29a Reflective coating layer 27a 'Upstream reflection portion, 27b' Downstream reflection portion: Embodiment 3
30 Halogen heater, (Embodiment 4), 30a Reflective coat layer N Fixing nip P Recording material g Gap

Claims (6)

A rotatable cylindrical member having flexibility, and radiant heating element arranged in the internal space of the tubular member, the tubular member is an inner peripheral surface and sliding freely disposed of, from the radiant heating element A heated plate that is heated by receiving the radiant heat of the radiant heat, and a reflecting member that is disposed in the internal space of the tubular member and that reflects the radiant heat of the radiant heating element toward the heated plate. A heating unit including a reflecting member having a cross-sectional shape of which the plate side is open ,
The recording material and a pressure member forming a fixing nip for pressurizing heater between the tubular member by sandwiching the tubular member between the heated plate,
And an image heating device for heating a toner image formed on a recording material ,
A light blocking member rotatable around the radiant heating element is provided in the internal space of the tubular member, and the light blocking member has a cylindrical rotation locus and has a width of a plurality of recording materials. Corresponding plural openings are formed in the rotation direction, and the opening corresponding to the width of the recording material is made to face the heated plate by rotating the light shielding member,
The radiation heating element is eccentric in the direction of the heated plate with respect to the rotation center position of the light shielding member,
The reflecting member is located in an internal space of the light shielding member and in a space outside the light shielding member, and is a portion that forms the opening. An upstream side reflection part and a downstream side reflection part respectively extending toward the upstream side and the downstream side of the fixing nip,
At a position between the main body reflection part and the upstream side reflection part of the reflection member and a position between the main body reflection part and the downstream side reflection part, in the passage area that is applied to the rotation trajectory of the light shielding member, A slit portion is provided through which the light blocking member can pass,
The image heating device , wherein the light shielding member is configured to rotate through the slit portion . The recording material conveyance direction of the width of the opening provided in the light shielding member, An apparatus according to claim 1, characterized in that substantially coincides with the recording material conveyance direction of the width of the fixing nip. Recording material conveyance direction of the width of the opening of the front Symbol reflecting member also An apparatus according to claim 2, characterized in that substantially coincides with the recording material conveyance direction of the width of the fixing nip. The light-shielding member has a cylindrical incomplete cylindrical body cut out along the entire length in the longitudinal direction corresponding to the maximum sheet passing width, and the longitudinal direction of the reflecting member along the longitudinal direction at the longitudinal end of the incomplete cylindrical body. The image heating apparatus according to claim 1 , further comprising a connecting portion that extends to the outside of the end portion, and an annular drive connecting portion that receives rotational drive outside the connecting portion. Before SL on the surface opposite to the heated plate of the radiant heating elements, An apparatus according to any one of claims 1 to 4, characterized in that the reflective coating layer is provided. An image forming unit for forming a toner image on the recording material,
An image forming apparatus comprising the, an image heating apparatus according to any one of claims 1 to 5.