JP2002287564A - Image forming apparatus and fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device by which surface temperature of a non- paper feeding part of a heating roller does not become excessively high temperature by a continuous printing even when the size and quality of a recording paper sheet is varied. SOLUTION: A cooling means to cool temperature rise of the non-paper feeding part of the recording paper of the heating roller 17A by air cooling is provided with a temperature sensor TSS to measure temperature distribution by being transferred and a movable shielding plate 173a to make a cooling area variable and cools the air by setting the cooling area according to a measurement result of temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for fixing a toner image formed by electrophotography on a transfer material by applying heat and pressure, and to form an image using the fixing device. The present invention relates to an image forming apparatus.

[0002]

2. Description of the Related Art As a means for fixing and fixing a toner image formed by electrophotography on a transfer material (hereinafter also referred to as recording paper), a heating roller (hereinafter also referred to as a fixing roller) and a pressure roller are used. A fixing device (hereinafter, also referred to as a fixing device) that passes a transfer material holding a toner image between a heating roller and a heating roller and applies heat and pressure to fuse and fix the toner is often used. ing. In the fixing device, the surface temperature of the heating roller is detected by a temperature sensor, the temperature of the heating roller surface is maintained at a predetermined high temperature of about 140 to 180 ° C., and the toner image is transferred between the rollers while the transfer material is being transferred. It is fused and fixed on the top.

Heat is removed by the transfer material passing through the heating roller by fixing, so that the surface temperature of the paper passing portion of the heating roller is lower than that of the non-paper passing portion during fixing. The temperature sensor measures the surface temperature of the heating roller, and the temperature of the heat source of the heating roller is determined because the temperature of the paper passing portion of the heating roller needs to be maintained at a predetermined high temperature to perform continuous printing. Control.

With this control, the surface temperature of the paper passing portion is maintained at a predetermined fixing temperature, but the temperature of the non-paper passing portion gradually becomes higher than that of the paper passing portion. If the heating roller becomes excessively high even if it is partially heated, the material is damaged and the life of the roller is extremely shortened.

Further, when the transfer material passes through a high-temperature non-sheet passing portion due to a change in paper size during continuous printing, the transfer material is wrapped around a heating roller, causing toner filming and fixing of the transfer material.・ Transfer failure will occur. Therefore, in the heating roller, it is desired that the temperature of the non-sheet passing portion is maintained close to the temperature of the sheet passing portion.

As means for avoiding an excessive rise in the temperature of the non-sheet passing portion, halogen lamps having different lengths, such as for A4R size and A3 size, are prepared as heating means for the heating roller. In some cases, a halogen lamp that is turned on in a heating roller is selected.

[0007]

In a general heating roller, since the pipe portion has a considerable heat capacity,
For example, turning on the halogen lamp for A4R size
When switching to A3 size printing after continuous printing of R size transfer material, it is difficult for the roller surface outside the A4R size to rapidly rise in temperature to a predetermined fixing temperature. Cannot perform A3 size printing. Conversely, when the printing is switched from A3 size continuous printing to A4R size printing, the outside of the A4R size becomes undesirably higher than a predetermined temperature due to the heat capacity of the roller.

An object of the present invention is to achieve the following three inventions. A first object of the present invention is to prevent a surface temperature of a non-sheet passing portion of a surface heat roller from becoming excessively high. It is another object of the present invention to provide an image forming apparatus. In order to detect the surface temperature of the heating roller, a non-contact infrared sensor is used together with a thermistor or the like. A second object of the present invention is to provide an image forming apparatus which is used for applications other than an infrared sensor and a temperature sensor. The temperature rise region and the degree of the temperature rise in the non-sheet passing portion of the heating roller vary depending on the size and type of the sheet to be passed.
A third object of the present invention is to provide a fixing device that performs appropriate cooling in response to fluctuations in the temperature rise area and the degree of temperature rise in the non-sheet passing portion.

[0009]

A first object of the present invention is to provide an image forming apparatus provided with a fixing device having a heating roller provided with a luminous body inside and a heat ray absorbing body on the outside. Temperature detecting means for detecting the temperature of the non-sheet-passing portion and the temperature of the non-sheet-passing portion. Image forming apparatus characterized by variable position and cooling area (invention of claim 1), and image forming apparatus having a fixing device having a heating roller provided with a luminous body inside and a heat ray absorber outside. The apparatus has a temperature detecting means for detecting a temperature of a paper passing portion and a non-paper passing portion of the heating roller, and a cooling area variable means for varying a cooling area by air cooling, and heats even after a printing operation is stopped. The feature is to continue the rotation of the roller and the cooling of the non-sheet passing area. And an image forming apparatus having a fixing device having a heating roller provided with a luminous body and a heat ray absorber on the outside, and a paper passing portion of the heating roller. An image forming apparatus comprising: a temperature detecting unit that detects a temperature of a non-sheet passing portion; a cooling region variable unit that varies a cooling region by air cooling; and an air volume control unit that controls a cooling air volume. (The invention of claim 7).

A second object of the present invention is to provide an image forming apparatus having a fixing member and a non-contact infrared sensor disposed close to each other so that the reflectance of the fixing member and the recording paper in the infrared portion are made different from each other so that the fixing member can be fixed. An image forming apparatus (invention of claim 11) for detecting the temperature of the image and the recording paper information;
In an image forming apparatus having a non-contact infrared sensor disposed in close proximity to a fixing member, the infrared sensor can be moved to detect the temperature of the fixing member and the information of the recording sheet from information at a plurality of positions. This is achieved by an image forming apparatus (the twelfth aspect of the invention).

A third object of the present invention is to provide a fixing device for fixing a toner image by applying heat and pressure to a transfer material, wherein a cooling means for cooling a rise in temperature of a non-sheet passing portion of the transfer material of a heating roller by air cooling. A fixing device having a temperature measuring means for moving and measuring a temperature distribution, and a cooling area changing means for changing a cooling area, wherein a cooling area is set based on a temperature measurement result. Item 14) and a fixing device for fixing a toner image by applying heat and pressure to a transfer material,
Cooling means for cooling the temperature rise of the non-sheet passing portion of the transfer material of the heating roller by air cooling has cooling area variable means for changing the cooling area, and the cooling area variable means includes a superposed plate member. A fixing device characterized in that it draws out and moves in a direction perpendicular to the paper passing direction to restrict a flow path (the invention according to claim 18).
Further, in a fixing device for fixing a toner image by applying heat and pressure to a transfer material, a cooling unit for cooling a temperature rise of a non-sheet passing portion of the transfer material of a heating roller by air cooling makes a cooling region variable. A fixing device (invention of claim 19) characterized in that the fixing device has a variable means, and the cooling area variable means deflects the upright plate-like member substantially in parallel with the paper direction to restrict the flow path. Achieved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described. Note that the description in this column does not limit the technical scope of the claims and the meaning of terms. Also, the following assertive description in the embodiment of the present invention indicates the best mode, and does not limit the meaning of the terms of the present invention or the technical scope.

(1) First, a fixing device to which the present invention is applied,
1 to 4 show an image forming process and each mechanism of an embodiment of an image forming apparatus using the fixing device.
This will be described with reference to FIG. FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of an image forming apparatus using a fixing device to which the present invention is applied, and FIG. 2 is an explanatory diagram showing the structure of the fixing device. 3 is an enlarged cross-sectional configuration diagram of the heat ray fixing rotating member of the fixing device of FIG. 2, and FIG. 4 shows the outer diameter and the thickness of the light-transmitting substrate of the heat ray fixing rotating member of the fixing device of FIG. It is sectional drawing.

According to FIG. 1, a photosensitive drum 10, which is an image forming body, has a light-transmitting member formed on a cylindrical base formed of a light-transmitting member such as glass or light-transmitting acrylic resin. It has a conductive layer and a photoconductor layer of an organic photosensitive layer (OPC).

The photosensitive drum 10 is rotated clockwise by the power from a driving source (not shown) in a state where the light-transmitting conductive layer is grounded, as shown by the arrow in FIG.

In the present embodiment, the exposure beam for image exposure is applied to the photoconductor layer of the photoconductor drum 10 at the image forming point, and the light attenuation characteristic of the photoconductor layer (photocarrier generation).
It is only necessary to have an exposure light amount having a wavelength that can provide an appropriate contrast with respect to. Therefore, the light transmittance of the light-transmitting substrate of the photosensitive drum in the present embodiment does not need to be 100%, and may have a characteristic of absorbing a certain amount of light when transmitting the exposure beam. . The point is that any suitable contrast can be provided. As a material of the light-transmitting substrate, an acrylic resin, particularly one obtained by polymerizing a methyl methacrylate monomer, is preferably used because of its excellent light-transmitting properties, strength, accuracy, surface properties, etc. Various translucent resins such as acryl, fluorine, polyester, polycarbonate, polyethylene terephthalate and the like used for the above can be used. Also,
It may be colored as long as it has a property of transmitting exposure light. As the light-transmitting conductive layer, a light-transmissive metal thin film made of indium tin oxide (ITO), tin oxide, lead oxide, indium oxide, copper iodide, Au, Ag, Ni, Al, or the like is used. Used as a film forming method, a vacuum deposition method, an active reaction deposition method, various sputtering methods, various CV
D method, dip coating method, spray coating method and the like can be used.
Various organic photosensitive layers (OPC) can be used as the photoconductor layer.

The organic photosensitive layer serving as the photosensitive layer of the photoconductor layer includes a charge generation layer (CGL) mainly composed of a charge generation substance (CGM) and a charge transport layer (CTM) mainly composed of a charge transport substance (CTM). And CTL). The two-layered organic photosensitive layer has a feature of high durability as an organic photosensitive layer due to the thick CTL. The organic photosensitive layer may have a single-layer structure containing a charge generation material (CGM) and a charge transport material (CTM) in one layer. And usually contains a binder resin.

A scorotron charger 11 as a charging unit described below, and an exposure optical system 1 as an image writing unit will be described.
2. The developing device 13 as a developing unit is prepared for an image forming process for each color of yellow (Y), magenta (M), cyan (C) and black (K), respectively. Are arranged in the order of Y, M, C, and K with respect to the rotation direction of the photosensitive drum 10 indicated by the arrow in FIG.

Scorotron charger 11 as charging means
Is mounted so as to face and be close to the photosensitive drum 10 in a direction perpendicular to the moving direction of the photosensitive drum 10 as an image forming body (the direction perpendicular to the plane of FIG. 1). A control grid (no symbol) maintained at a predetermined potential with respect to the body layer;
As a, for example, a sawtooth electrode is used, and a charging action (in this embodiment, negative charging) is performed by corona discharge having the same polarity as that of the toner, thereby giving a uniform potential to the photosensitive drum 10. As the corona discharge electrode 11a, a wire electrode or a needle electrode may be used.

The exposure optical system 12 for each color has a linear exposure element (LED) in which a plurality of LEDs (light emitting diodes) as light emitting elements for image exposure light are arranged in an array in parallel with the axis of the photosensitive drum 10. (Not shown) and a selfoc lens (not shown) as an equal-magnification imaging element are configured as an exposure unit attached to a holder. An exposure optical system 1 for each color is placed on a cylindrical holder 20 as an exposure optical system holding member.
2 is mounted and housed inside the substrate of the photosensitive drum 10. Other exposure elements include FL (phosphor emission),
A linear element in which a plurality of light emitting elements such as EL (electroluminescence) and PL (plasma discharge) are arranged in an array is used.

An exposure optical system 12 as an image writing means for each color sets an exposure position on a photosensitive drum 10 between a scorotron charger 11 and a developing device 13 and a photosensitive member with respect to the developing device 13. It is arranged inside the photoconductor drum 10 in a state provided on the upstream side in the rotation direction of the drum 10.

The exposure optical system 12 performs image processing based on image data of each color sent from a separate computer (not shown) and stored in a memory, and then performs image processing on the uniformly charged photosensitive drum 10. Exposure is performed to form a latent image on the photosensitive drum 10. The emission wavelength of the light-emitting element used in this embodiment is usually 6 for the toners of Y, M, and C, which have high translucency.
The wavelength in the range of 80 to 900 nm is good, but the wavelength may be shorter than this, since the color toner does not have sufficient translucency since image exposure is performed from the back surface.

The developing device 13 as a developing means for each color includes
Inside yellow (Y), magenta (M), cyan (C)
Alternatively, it contains a black (K) two-component (or one-component) developer and is formed of, for example, a cylindrical non-magnetic stainless steel or aluminum material having a thickness of 0.5 to 1 mm and an outer diameter of 15 to 25 mm, respectively. And a developing sleeve 13a as a developer carrier.

In the developing area, the developing sleeve 13a is kept out of contact with the photosensitive drum 10 with a predetermined gap, for example, 100 to 1000 μm, by abutting rollers (not shown). At the closest position, it rotates in the forward direction, and at the time of development, an AC voltage AC is superimposed on a DC voltage of the same polarity as the toner (in the present embodiment, a negative polarity) or a DC voltage with respect to the developing sleeve 13a. By applying the developing bias voltage, non-contact reversal development is performed on the exposed portion of the photosensitive drum 10. At this time, the accuracy of the development interval needs to be about 20 μm or less in order to prevent image unevenness.

As described above, the developing unit 13 transfers the electrostatic latent image formed on the photosensitive drum 10 by the charging by the scorotron charger 11 and the image exposure by the exposure optical system 12 in a non-contact state. Reversal development is performed with toner having the same polarity as the charge polarity of No. 10 (in the present embodiment, the photosensitive drum is negatively charged, and the toner has a negative polarity).

At the start of image formation, the photosensitive drum 10 is rotated clockwise as indicated by an arrow in FIG. 1 by starting an unillustrated image forming body driving motor, and at the same time, the photosensitive drum 10 is charged by the charging action of the Y scorotron charger 11. Application of a potential to 10 starts. After a potential is applied to the photosensitive drum 10, exposure (image writing) by a first color signal, that is, an electrical signal corresponding to Y image data is started in the Y exposure optical system 12, and the rotation of the photosensitive drum 10 is started. By scanning, an electrostatic latent image corresponding to the yellow (Y) image of the original image is formed on the photosensitive layer on the surface. This latent image is reversely developed in a non-contact state by the Y developing device 13, and a yellow (Y) toner image is formed on the photosensitive drum 10.

Next, the photoreceptor drum 10 places an M scorotron charger 11 on the yellow (Y) toner image.
A potential is applied by the charging action of the M exposure optical system 12
Exposure (image writing) is performed using an electrical signal corresponding to the second color signal of m, i.e., magenta (M) image data.
The magenta (M) toner image is formed on the yellow (Y) toner image by non-contact reversal development by the developing device 13.

According to the same process, the cyan (C) toner image corresponding to the third color signal is further processed by the C scorotron charger 11, the exposure optical system 12 and the developing device 13, and the K scorotron charger 11. , Exposure optical system 1
A black (K) toner image corresponding to the fourth color signal is sequentially superimposed and formed by the second and developing units 13, and a color toner image is formed on the peripheral surface within one rotation of the photosensitive drum 10. You.

As described above, in this embodiment, Y, M,
The exposure of the organic photosensitive layer of the photoconductor drum 10 by the C and K exposure optical systems 12 is performed through a transparent substrate from the inside of the photoconductor drum 10. Therefore, the exposure of the image corresponding to the second, third, and fourth color signals can form an electrostatic latent image without being shielded by the previously formed toner image, which is preferable. Photoconductor drum 1
0 may be exposed from outside.

On the other hand, the recording paper P as a transfer material is selectively taken out from a paper feed cassette 15A or 15B as a transfer material storage means in accordance with the paper size or paper quality, and is sent out by a feed roller (no code). , And are conveyed to the timing roller 16 by a feeding roller (no symbol).

The recording paper P is synchronized with the color toner image carried on the photosensitive drum 10 by the driving of the timing roller 16, and the paper charger 1 serving as a paper charging means is synchronized.
Due to the electrification of 50, the toner is attracted to the conveyor belt 14a and fed to the transfer area. The recording paper P, which is closely transported by the transport belt 14a, is moved around the photosensitive drum 10 by a transfer unit 14c as a transfer unit to which a voltage having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied in a transfer area. The color toner images on the surface are collectively transferred to the recording paper P.

The recording paper P on which the color toner image has been transferred is
The paper is discharged by a paper separation AC neutralizer 14h as a transfer material separating unit, separated from the transport belt 14a, and transported to the fixing device 17.

The fixing device 17 has an upper roll-shaped heat ray fixing roller 17a for fixing a color toner image, and a lower roll-shaped roller provided opposite to the upper heat ray fixing roller 17a. And a pressure roller 47a as a fixing member.
In the center of the inside of 7a, a halogen lamp 1 that emits heat rays such as infrared rays or far infrared rays including visible light depending on the light source is provided.
71 g, a xenon lamp (not shown), and the like are provided as heat ray irradiation means.

Heat ray fixing roller 17a and pressure roller 47a
The recording paper P is sandwiched by a nip portion N formed between
By applying heat and pressure, the color toner image on the recording paper P is fixed, and the recording paper P is sent by the paper discharge roller 18 and discharged to a tray on the upper portion of the apparatus.

The toner remaining on the peripheral surface of the photosensitive drum 10 after the transfer is transferred to a cleaning blade 19 provided in a cleaning device 19 as an image forming body cleaning means.
Cleaning is performed by a. The photosensitive drum 10 from which the residual toner has been removed is uniformly charged by the scorotron charger 11, and enters the next image forming cycle.

(2) Next, a fixing device to which the present invention is applied will be described. Heat ray fixing roller 17 in fixing device 17
a is a surface heating roller in which a heating element is disposed inside and a heat ray absorber is disposed outside, and the surface of the roller absorbs heat rays and becomes high in temperature. The pressure roller 47a also has a heat source, and heats the recording paper P from both sides. , Fixing is performed. The fixing device having such a configuration is extremely effective when fixing a color image having a relatively large amount of toner adhered to a transfer material, but the fixing device to which the present invention is applied does not necessarily have a heat source in the pressure roller 47a. You don't have to.

As shown in FIG. 2, the fixing device 17 is a hot-ray fixing roller 17a as a roll-shaped hot-ray fixing rotating member having an upper elasticity for fixing a toner image on a transfer material.
And a lower pressure roller 47a as a roll-shaped fixing member provided opposite to the upper heat ray fixing roller 17a, and formed between the elastic heat ray fixing roller 17a and the pressure roller 47a. Width 5-20mm
The recording paper P is sandwiched between the nip portions N, and the toner image on the recording paper P is fixed by applying heat and pressure. On the hot-wire fixing roller 17a as a roll-shaped hot-wire fixing rotating member provided on the upper side, the fixing separation claw TR3 and the pressing force of each pressing spring SPa are applied in the rotation direction of the hot-wire fixing roller 17a from the position of the nip portion N. Further, a cleaning roller TR1, a heat equalizing roller TR4, an oil application web TR2, and the like are provided as contact members that are pressed and contacted with the heat ray fixing roller 17a. The oil-coated web TR2 as a contact member using a felt member impregnated with oil is pressed against the hot-wire fixing roller 17a by a pressing roller ROa pressed by a pressing spring SPa. Oil is applied to the heat ray fixing roller 17a while being intermittently wound up from the winding roller RMa to the winding roller RMb. Cleaning roller TR1 and heat equalizing roller T as contact members, respectively
R4 is pressed against the heat ray fixing roller 17a by the pressing force of the pressing spring SPa, and is contacted with the heat ray fixing roller 17a.
Is rotated by the rotation of. Cleaning roller TR
1 cleans toner and oil on the peripheral surface of the heat ray fixing roller 17a. Therefore, the heat equalizing roller TR
4, and a temperature sensor TS1, which will be described later, is a temperature detecting means for measuring the temperature of the sheet passing portion of the heat ray fixing roller 17a.
It is provided on the peripheral surface of the heat ray fixing roller 17a that has been cleaned between the cleaning roller TR1 and the oil application web TR2. The transfer material after fixing is separated by the fixing separation claw TR3. The heat distribution roller TR4 using a metal roller member having good thermal conductivity, such as an aluminum material or a stainless steel material, or a heat pipe using a heat pipe makes the heat generation temperature distribution on the peripheral surface of the heat ray fixing roller 17a heated by the heat ray absorption layer 171b uniform. Is done. The heat uniformizing roller TR4 equalizes the temperature unevenness of the heat ray fixing roller 17a in the vertical and horizontal directions due to the passage of the transfer material.

A heat ray fixing roller 17a provided on the upper side and serving as a heat ray fixing rotating member for fixing a toner image on a transfer material includes a cylindrical light transmitting base 171a and an outer side of the light transmitting base 171a. (Transparent elastic layer 171d)
A heat-absorbing layer 171b and a release layer 171c are provided in this order, or as described in detail in FIG. 3 below, a cylindrical light-transmitting substrate 171a and an outer surface (outer peripheral surface) of the light-transmitting substrate 171a. ), The light-transmitting elastic layer 171d and the heat ray absorbing layer 1 on the outer side (outer peripheral surface) of the light-transmitting elastic layer 171d.
It is configured as a soft roller having an outer diameter of about 25 to 50 mm, in which a combined layer 171B, which is a heat ray absorbing layer, is provided in that order, integrating the release layer 71b with the release layer 171c.
A halogen lamp 171g or a xenon lamp (not shown) is provided in the center of the translucent substrate 171a as a heat ray irradiating means for emitting heat rays such as infrared rays or far infrared rays including visible light depending on the light source. The heat ray fixing roller 17a as a heat ray fixing rotating member is configured as a highly elastic soft roller as described later. Halogen lamp 1
Heat rays emitted from 71 g or a xenon lamp (not shown) are absorbed by the heat ray absorbing layer 171b (or the dual-purpose layer 171B which is a heat ray absorbing layer) to form a roll-shaped heat ray fixing rotating member capable of rapid heating. You.

The lower pressure roller 47a as a roll-shaped fixing member provided opposite to the upper heat ray fixing roller 17a is, for example, a cylindrical metal pipe 471a made of an aluminum material. For example, a silicon material is used for the outer peripheral surface of the metal pipe 471a, and the rubber hardness is 10 Hs or more.
40Hs (JIS, A rubber hardness), thickness (wall thickness) 2
It is configured as a soft roller having an outer diameter of about 25 to 50 mm on which a rubber roller 471b made of a thick rubber layer having a thickness of 7 mm is formed. An elastic rubber roller having high heat insulating property is used for the lower roll-shaped fixing member to prevent heat from diffusing from the upper heat ray fixing rotating member to the lower fixing member, and to secure a wide nip width. In addition, the surface of the rubber roller 471b is pressed by the pressing force of the pressing spring SPa, and is driven and rotated by the pressing force of the pressing spring SPa. The heat equalizing roller TR4 is provided, and the heat uniformizing roller TR4 equalizes the heat generation temperature distribution on the peripheral surface of the pressure roller 47a.
As the heat equalizing roller TR4, it is preferable to use a heat pipe that has both heat storage and heat radiation. Further, a halogen lamp 471c as a heat source may be provided in the center of the inside of the metal pipe 471a. Of course, the same configuration as the upper heat ray fixing roller 17a of the present invention may be used for the lower pressure member.

A flat nip portion N is formed between the upper soft roller and the lower soft roller to fix the toner image.

TS1 is a temperature sensor which is mounted on the upper heat ray fixing roller 17a and is a temperature detecting means using, for example, a contact type thermistor for controlling the temperature. TS2 is mounted on the lower pressure roller 47a. A temperature sensor using, for example, a contact-type thermistor for controlling the temperature. As the temperature sensors TS1 and TS2, non-contact type sensors can be used in addition to the contact type.

According to FIG. 3, the configuration of the heat ray fixing roller 17a is such that the thickness (wall thickness) of the cylindrical light transmitting substrate 171a is 0.5 to 0.5 as shown in FIG. 5mm,
Pyrex (registered trademark) glass having a thickness of preferably 1 to 3 mm and transmitting heat rays such as infrared rays or far infrared rays from a halogen lamp 171 g or a xenon lamp (not shown);
Ceramic materials such as sapphire (Al ₂ O ₃ ) and CaF ₂ (having a thermal conductivity of (5 to 20) × 10 ⁻¹ W / m · K and a specific heat of (0.5 to 2.0) × 10 ³ J / kg · K, specific gravity is 1.
5 to 3.0) are mainly used. Transparent resin using polyimide, polyamide, etc. (Thermal conductivity is (2-4)
× 10 ^-1 W / m · K, specific heat is (1-2) × 10 ³ J / k
g · K, specific gravity of 0.8 to 1.2) and the like can also be used. As described above, the translucent substrate 171a does not have good thermal conductivity.

The light-transmitting elastic layer 171d has a thickness (thickness).
A heat-ray-transmitting silicon rubber layer or fluorine-containing rubber that transmits heat rays (infrared ray or visible ray including visible light depending on the light source) using 0.5 to 5 mm, preferably 1 to 3 mm thick silicon rubber or fluoro rubber, for example. Layer (base layer)
Is formed. For the light-transmitting elastic layer 171d, in order to cope with a high speed, a method of improving the thermal conductivity by mixing a powder of a metal oxide such as silica, alumina or magnesium oxide as a filler into the base layer is adopted. Rate is (1
~ 3) × 10 ^-1 W / m · K, specific heat is (1-2) × 10 ³
A silicon rubber layer or a fluorine rubber layer having J / kg · K and a specific gravity of 0.9 to 1.0 is used. The silicon rubber layer and the fluorine rubber layer are made of a light-transmitting substrate 171a having a thermal conductivity of a glass member.
Since the thermal conductivity is lower than (5 to 20) × 10 ⁻¹ W / m · K, it functions as a heat insulating layer. Increasing the thermal conductivity generally tends to increase the rubber hardness.
Those of Hs become high to nearly 60 Hs (JIS, A rubber hardness). Preferred rubber hardness is 10 to 50 Hs
It is. Most of the translucent elastic layer 171d of the heat ray fixing rotating member is occupied by the base layer, and the amount of compression during pressurization is determined by the rubber hardness of the base layer. Translucent elastic layer 1
The intermediate layer 71d is coated with a fluorine-based rubber, preferably in a thickness of 20 to 300 μm, as an oil-resistant layer to prevent oil swelling. The wavelength of the heat ray passing through the translucent elastic layer 171d is 0.1 to 20 μm, preferably 0.3 to 20 μm.
Since the particle diameter is 3 μm, the filler used as the hardness and thermal conductivity modifier described above has a particle diameter of 1/1 / wavelength of the heat ray.
2, preferably not more than 1/5 and having an average particle diameter of 1 μm or less, preferably 0.1 μm or less, including primary and secondary particles (transmission of infrared or far-infrared light including visible light depending on the light source) The translucent elastic layer 171d may be formed by dispersing fine particles of a metal oxide such as titanium oxide, aluminum oxide, zinc oxide, silicon oxide, magnesium oxide, and calcium carbonate in a resin binder. It is preferable that the average particle diameter including the primary and secondary particles in the layer is 1 μm or less, preferably 0.1 μm or less in order to prevent light scattering and reach the heat ray absorbing layer 171b. By providing the translucent elastic layer 171d, the heat ray fixing roller 17a as a heat ray fixing rotating member is configured as a soft elastic roller.

As the heat ray absorbing layer 171b, the remaining heat rays emitted from the halogen lamp 171g or the xenon lamp (not shown) and absorbed by the light transmitting base 171a and the light transmitting elastic layer 171d are used as the heat transmitting layer 171b. A heat ray fixing rotating member capable of absorbing 90 to 100%, preferably 95 to 100% of heat rays, which is about 100% of the heat rays transmitted through the 171a and the light transmitting elastic layer 171d, by the heat ray absorbing layer 171b and capable of rapid heating. As described above, carbon black, graphite, iron black (Fe
10% by mass of powder such as ₃ O ₄ ), various ferrites and their compounds, copper oxide, cobalt oxide, and red iron oxide (Fe ₂ O ₃ ).
A heat ray absorbing layer 171b having a thickness of 25 to 200 μm, preferably 30 to 150 μm, is formed on the outside (outer peripheral surface) of the light-transmitting elastic layer 171d by spraying or coating. The thermal conductivity of the heat ray absorbing layer 171b is
By adding an absorbent such as carbon black, the base layer of the translucent elastic layer 171d (having a thermal conductivity of (3 to 10) ×
(3-100) × 1 higher than 10 ^-1 W / m · K)
It can be set to 0 ^-1 W / m · K. Heat ray absorption layer 1
The specific heat of 71b is (〜2.0) × 10 ³ J / kg · K, and the specific gravity is ０．９0.9. As the heat ray absorbing layer 171b, a metal roller member such as a nickel electroformed roller may be provided with a similar thickness. At this time, it is preferable that the inside (the inner peripheral surface) is subjected to black oxidation treatment in order to absorb heat rays.
If the heat ray absorption rate in the heat ray absorption layer 171b is lower than about 90%, for example, about 20 to 80%, heat rays leak,
When the heat ray fixing roller 17a as a heat ray fixing rotating member is used for forming a monochrome image due to the leaked heat rays, if the black toner adheres to the surface of the heat ray fixing roller 17a at a specific position due to filming or the like, the adhering portion is formed by the leaked heat rays. Then, heat is generated due to heat ray absorption in that portion, and the heat ray absorption layer 171b is damaged. Further, when used for forming a color image, the absorption efficiency of the color toner is generally low, and there is a difference in the absorption efficiency between the color toners, resulting in poor fixing or uneven fixing. Therefore, the remaining heat rays emitted from the halogen lamp 171g or the xenon lamp (not shown) and absorbed by the light-transmitting base 171a and the light-transmitting elastic layer 171d form the light-transmitting base 17
1a and the heat ray absorbing layer 171d so that the heat ray transmitted through the light transmitting elastic layer 171d is completely absorbed by the heat ray absorbing layer 171b.
90-100 which is equivalent to about 100% of the heat ray absorption rate of 1b
%, Preferably 95 to 100%. Thereby, the color toner, which is difficult to fix by heat rays due to different spectral characteristics, is favorably melted. Particularly, in the color image formation in FIG. 1, it is difficult to fix by heat rays due to different spectral characteristics. The superimposed color toner image on the transfer material having a thick toner layer is fused well. Also,
When the thickness of the heat ray absorbing layer 171b is less than 25 μm and thin, the heating rate due to the absorption of the heat ray in the heat ray absorbing layer 171b is high, but the heat ray absorbing layer 171b due to local heating by the thin film.
If the thickness of the heat ray absorbing layer 171b exceeds 200 μm, the heat conduction becomes poor or the heat capacity becomes large and rapid heating becomes difficult. By setting the heat ray absorption rate of the heat ray absorption layer 171b to 90 to 100%, which is about 100%, preferably 95 to 100%, or setting the thickness of the heat ray absorption layer 171b to 25 to 200 μm, preferably 30 to 150 μm, Local heat generation in the absorption layer 171b is prevented, and uniform heat generation is performed. Further, the wavelength of the heat ray projected on the heat ray absorbing layer 171b is 0.1 to 20 μm, preferably 0.3 to 3 μm.
Therefore, an adjuster for hardness and thermal conductivity is added as a filler, but the average particle size including primary and secondary particles having a particle size of 、, preferably １ ／ or less of the wavelength of the heat ray is included. Is 1μ
Metals such as titanium oxide, aluminum oxide, zinc oxide, silicon oxide, magnesium oxide, calcium carbonate, etc. having a heat ray transmission of not more than m, preferably not more than 0.1 μm (depending on the light source, transmitting infrared or far infrared rays including visible light). The heat ray absorbing layer 171b may be formed by dispersing 5 to 50% by mass of oxide fine particles in a resin binder. This allows the heat rays to enter the heat ray absorbing layer 171b and prevent heat generation at the interface. In this way, the heat capacity of the heat ray absorbing layer 171b is reduced so that the temperature rises immediately. Therefore, the temperature of the heat ray fixing roller 17a as a heat ray fixing rotating member is lowered, and the fixing unevenness occurs. To prevent.

Further, a PFA (fluororesin) tube having a thickness of 25 to 75 μm is coated on the outer side (outer peripheral surface) of the heat ray absorbing layer 171b separately from the heat ray absorbing layer 171b to improve the releasability from the toner. Or fluororesin (PFA)
Alternatively, a release layer 171c having a thermal conductivity of (3 to 100) × 10 ⁻¹ W / m · K is provided by applying a PTFE) paint of 25 to 75 μm (separation type).

Further, as shown in the cross section of FIG. 3B, carbon black, graphite, iron black (Fe
10% by mass of powder such as ₃ O ₄ ), various ferrites and their compounds, copper oxide, cobalt oxide, and red iron oxide (Fe ₂ O ₃ ).
To the extent, a fluororesin (PF
A or PTFE) mixed into the paint and blended.
The heat ray absorbing layer 171b and the release layer 171c are also used as described above, and the heat ray absorbing layer 171b and the release layer 171c are integrally formed and have a releasing property. It is preferable to form an elastic roll-shaped heat ray fixing rotating member formed outside (outer peripheral surface) of the translucent elastic layer 171d formed outside (outer peripheral surface) of the optical base 171a. Heat ray absorbing layer 171b and release layer 1
The combined layer 171B (hereinafter, simply referred to as a combined layer 171B), which is a heat ray absorbing layer in which the PFA 71c is integrated, is a carbon-containing PFA having a thickness of about 25 to 200 μm.
A tube coated with a (perfluoroalkoxy) tube is preferably used. The layer thickness of the dual-purpose layer 171B can be reduced to 25 to 200 μm by providing a surface layer (a layer for protection) in each of the following embodiments. The thermal conductivity of the dual-purpose layer 171B integrating the heat ray absorbing layer 171b and the release layer 171c is substantially the same as that of the heat ray absorbing layer 171b, and is (3 to 10) × 10 ⁻¹ W / m ·. K. As described above, the light-transmitting substrate 171a is emitted from the halogen lamp 171g or the xenon lamp (not shown).
The heat ray absorptivity of the dual-purpose layer 171B is substantially reduced so that the remaining heat rays absorbed by the light-transmitting elastic layer 171d completely absorb the heat rays transmitted through the light-transmitting substrate 171a and the light-transmitting elastic layer 171d. 90 to 100%, which is 100%, preferably 95 to 100%. When the heat ray absorption rate of the dual-purpose layer 171B is lower than about 90%, for example, about 20 to 80%, the heat ray leaks, and when the heat ray fixing rotary member is used for monochrome image formation due to the leaked heat ray, When black toner adheres to the surface of the heat ray fixing rotating member at a specific position due to, e.g., mining or the like, heat is generated from the adhered portion due to the leaked heat rays, and heat generated by heat ray absorption is further superimposed at that portion, thereby damaging the dual-purpose layer 171B. In addition, when used for forming a color image, the absorption efficiency of the color toner is generally low, and there is a difference in the absorption efficiency between the color toners, resulting in poor fixing or uneven fixing. Therefore, the remaining heat rays emitted from the halogen lamp 171g or the xenon lamp (not shown) and absorbed by the light-transmitting base 171a and the light-transmitting elastic layer 171d form the light-transmitting base 171a and the light-transmitting elastic layer 171d. In order to completely absorb the heat rays transmitted through the heat ray fixing rotating member, the heat ray absorptivity of the dual-purpose layer 171B is about 90% to 100%, preferably about 100%, preferably 9%.
5 to 100%. In addition, local heat generation in the dual-purpose layer 171B is also prevented, and uniform heat generation is performed. The wavelength of the heat ray projected on the dual-purpose layer 171B is 0.1 to 20 μm.
m, preferably 0.3 to 3 μm, so that a filler for adjusting hardness or thermal conductivity is added as a filler. 2
The average particle size including the secondary particles is 1 μm or less, preferably 0.1 μm or less.
Fine particles of metal oxide such as titanium oxide, aluminum oxide, zinc oxide, silicon oxide, magnesium oxide, calcium carbonate, etc. having a heat ray transmission of 1 μm or less (infrared ray or visible ray including visible light depending on the light source) are used as resin binder. May be used to form the dual-purpose layer 171B.

FIG. 4 is a cross-sectional view of the heat ray fixing roller 17a. The outer diameter φ of the cylindrical light transmitting base 171a of the heat ray fixing roller 17a as a roll-shaped heat ray fixing rotating member is about 15 to 45 mm. As the thickness t, a thicker one is better in terms of strength and a thinner one is better in terms of heat capacity. However, from the relationship between strength and heat capacity, the outer diameter of the cylindrical light-transmitting base 171a is large. The relationship between φ and the thickness (wall thickness) t is 0.02 ≦ t / φ ≦ 0.20, preferably 0.04 ≦ t / φ ≦ 0.10. When the outer diameter φ of the transparent substrate 171a is 40 mm, the thickness t of the transparent substrate 171a is 0.8 mm ≦ t ≦ 8 m.
m, preferably 1.6 mm ≦ t ≦ 4.0 mm. When t / φ is less than 0.02 in the translucent substrate 171a, the strength becomes insufficient, and when t / φ exceeds 0.20, the heat capacity increases and the heating of the heat ray fixing roller 17a is prolonged. Further, even if the translucent substrate 171a is used, it may absorb about 5 to 25% of heat rays depending on the material. Similarly, the translucent elastic layer 171d may have a thickness of 5 to 25 depending on the material.
% Of the heat ray may be absorbed, and it is preferable that the heat ray is thin as long as the strength can be maintained.

The fixing unit (nip portion) is formed by using the above-mentioned heat ray fixing rotating member in the fixing device 17 described with reference to FIG.
Quick start (rapid heating)
Further, a fixing device capable of fixing the heat can be obtained, and furthermore, the elasticity of the rotating member for heat ray fixing pressurizes the soft fixing portion (nip portion) and the heating of the rotating member for heat ray fixing by the heat ray absorbing layer. The color toners, which are difficult to fix due to heat rays, are satisfactorily melted due to the differences in the heat rays, and quick start (rapid heating) fixing of the color toners becomes possible. Also, an energy saving effect can be obtained.

(3) Also in the fixing device 17 having the surface heat generating roller described with reference to FIGS. 2 to 4, the heat ray fixing roller 17a has a temperature difference between the paper passing portion and the non-paper passing portion of the transfer material at the time of fixing. When continuous printing of the same size is performed for a long time, the halogen lamp 171g continues to be turned on based on the temperature information from the temperature sensor TS1 to supply heat to the paper passing portion. Since no heat is taken away by the transfer material in the portion, the surface temperature of the non-sheet passing portion becomes considerably higher than the fixing temperature, and the heat ray fixing roller 17a is damaged and its life is shortened. In the meantime, the fixing performance is reduced.

In the first embodiment described here, the temperature sensor TS1 for detecting the temperature of the non-sheet passing portion in addition to the temperature sensor TS1 for detecting the temperature of the sheet passing portion of the heat ray fixing roller 17a.
S, and has a cooling area changing means for changing the cooling area by air cooling, and the temperature detection position and the cooling area of the non-sheet passing section are made variable according to the size of the sheet to be passed. This is to prevent an excessive rise in temperature.

(Embodiment 1) The image forming apparatus of this embodiment is
A plurality of temperature sensors (TSS1 and TSS2 in this embodiment) for detecting the temperature of the non-sheet passing portion are provided, and a temperature sensor for detecting the temperature of the non-sheet passing portion is determined in accordance with the paper size of the recording sheet to be fixed. The non-sheet passing portion is cooled based on the temperature detected by the temperature sensor.

FIG. 5 is a control block diagram of the first embodiment.
Is an explanatory diagram. When the user specifies the paper size for printing, the control unit carries out the recording paper of the specified size from the paper feed cassette 15A or 15B and forms an image.
At the same time, it is determined which of the temperature sensors TSS1 and TSS2 is to be used to detect the temperature of the non-sheet passing portion.

FIG. 6 shows the situation when fixing is performed on recording paper having different paper sizes (A) and (B). The fixing of the heat ray fixing roller 17a is performed based on temperature detection by the temperature sensor TS1. temperature control is performed, the roller surface temperature at the time when the sheet passing and non-passing paper for sheet passing range is come vary the temperature of the fixing temperature T ₀ that appropriate for performing fixing is maintained. On the other hand, in the non-sheet passing area, when continuous printing is performed using recording paper of the same size, the roller surface temperature gradually increases. On the roller surface, a temperature gradient is shown at the boundary between the paper passing portion and the non-paper passing portion, and this temperature gradient range (cooling boundary) depends on the heat capacity of the roller and the heat conductivity in the axial direction of the roller. In the heat ray fixing roller 17a, the cooling boundary is between 0 ± 5 mm. It is necessary to avoid this cooling boundary in order to detect the temperature of the sheet passing portion and the non-sheet passing portion. The temperature detection of the non-sheet passing portion is performed at a position near the sheet passing portion avoiding the cooling boundary.

The control unit detects the temperature in the non-sheet-passing range by the temperature sensor TSS1 when fixing the (A) size recording paper, and performs the fixing when fixing the (B) size recording paper.
The temperature sensor TSS2 detects the temperature in the non-sheet passing range.

It is not necessary to detect the temperature of the non-sheet passing portion for each print. For example, the temperature is detected every 5 to 10 prints during continuous printing. When the temperature detected by the temperature sensor TSS reaches a temperature of, for example, (fixing temperature T ₀ ) + 10 ° C. at which the cooling is necessary, the control unit sets a cooling area corresponding to the paper size to be fixed by the cooling area variable unit and air-cools. , And cooling is continued until the temperature detected by the temperature sensor TSS becomes the fixing temperature T ₀ , for example. For cooling by air cooling, it is most effective to blow cold air with a nozzle onto the roller surface, but the wind speed is 7 m / s.
When an airflow is formed along the roller surface by the front and rear cold air, heat is efficiently removed from the roller surface.

(Embodiment 2) The image forming apparatus of this embodiment is
The temperature sensor TSS for detecting the temperature of the non-sheet passing portion is movable, and the temperature sensor TSS is moved to the most appropriate detection position of the non-sheet passing portion according to the paper size of the recording paper to be fixed and moved. The non-sheet passing portion is cooled based on the temperature detection of the temperature sensor TSS.

FIG. 7 is a control block diagram of the second embodiment.
Is an explanatory diagram. The difference from the first embodiment is that the control unit determines where the temperature sensor TSS should be located based on the paper size information, moves to the location, and detects the temperature. . Specific examples of the method of moving the temperature sensor TSS and the cooling area changing means will be described later.

(Embodiment 3) The image forming apparatus of this embodiment is
For example, regarding the image forming apparatuses described in the first and second embodiments,
Even after the printing operation is stopped, the rotation of the heat ray fixing roller 17a and the cooling of the non-sheet passing portion are continued without turning on the halogen lamp 171g.

After the printing operation is stopped, the heat ray fixing roller 17
Even if the surface a is cooled by air cooling, the inside of the roller is in a considerably high temperature state even if the surface temperature is cooled. Therefore, when cooling is stopped immediately after the printing operation is stopped, the roller surface temperature rises again and the heat ray absorbing layer 171b
Becomes high temperature, damaging the material and deteriorating the fixing performance. In the present embodiment, when the non-sheet passing portion is in a state of cooling when the printing operation is stopped, the control portion continues to rotate the heat ray fixing roller 17a and cool the non-sheet passing portion after the printing operation is stopped. Time (for example, during 1 min.)
Alternatively, the operation is continued until the temperature detected by the temperature sensor TSS reaches a predetermined temperature (for example, the fixing temperature T ₀ -10 ° C.), and then the operation is stopped.

(Embodiment 4) The image forming apparatus of this embodiment is
In addition to the temperature sensor TS1 for detecting the temperature of the paper passing portion of the heat ray fixing roller 17a, a temperature sensor TSS for detecting the temperature of the non-paper passing portion is provided, and a cooling region variable means for varying the cooling region by air cooling; Air flow control means for controlling the temperature detection position of the non-sheet passing portion and the cooling area in accordance with the paper size, and changing the amount of air for cooling the cooling region, It is designed to prevent temperature rise,
FIG. 10 is a control block diagram of the present embodiment.

In the image forming apparatuses described in the first and second embodiments, whether or not to perform cooling by air cooling is determined based on the temperature of the non-sheet passing portion detected by the temperature sensor TSS. Further, based on the measured temperature, the control unit determines whether or not to perform the cooling by blowing strongly, and switches between strong and weak blowing. Specifically, for example, the drive voltage of the fan motor is switched to change the wind speed to 7 m / s or more, for example, 8 m / s.
And a low wind speed of 6 m / s.

As described above, the change of the air volume or the air speed is performed based on the detected temperature in the non-sheet passing portion, but may be changed according to other fixing conditions. Next, such an image forming apparatus will be described.

In this embodiment, as shown in a sectional view of FIG. 9, two long and short halogen lamps 1 are provided in the heat ray fixing roller 17a.
71 g (L) and 171 g (S) are built in. The halogen lamp 171 g (L) has a length long enough to fix A3 size recording paper, and 171 g (S) is A
It has a length for 4R. FIG. 10 is a control block diagram of an image forming apparatus having such a fixing device. When the user specifies the paper size for printing, the control unit operates as described in the first embodiment.
At that time, the halogen lamp to be turned on is determined according to the paper size.Fixing is performed under the turned on halogen lamp.Cooling of the non-paper passing part is performed with strong or weak cooling depending on the fixing conditions as shown in the following example. Done. When the halogen lamp 171g (L) is turned on and the B4 size paper is fixed, the non-sheet passing portion outside the B4 size is cooled by strong air cooling. When the halogen lamp 171g (L) is turned on and the A3 size paper is fixed, the non-sheet passing portion outside the A3 size is cooled by weak air cooling. When the halogen lamp 171g (S) is turned on and the A4R paper is fixed, the non-sheet passing portion outside the A4R size is cooled by weak air cooling.

By performing the cooling process corresponding to the fixing conditions, the favorable fixing process can be continuously performed without receiving any damage to the heat ray fixing roller 17a.

(4) A non-contact infrared sensor is used together with a thermistor or the like as a temperature sensor for detecting the temperature of a fixing member such as a fixing roller.

A temperature sensor such as a thermistor detects the temperature of the roller surface at a position very close to or in contact with the fixing roller whose temperature is to be measured. Therefore, a temperature sensor such as a thermistor is often damaged in the event of a jam such as the recording paper being wound around a fixing roller during fixing.

On the other hand, in the non-contact infrared sensor, light is received by a sensor condensed in a parabolic shape.
Temperature detection is performed at an arbitrary distance, for example, 20 mm from the fixing roller. Specifically, the temperature of the object to be measured is obtained from an output voltage that changes according to the temperature of the object to be measured, for example, according to a graph shown in FIG.

(Embodiment 5) In the image forming apparatus of this embodiment, the temperature of the fixing member and the recording paper information are detected by using a non-contact infrared sensor to detect the temperature of the fixing member. The recording paper information includes (a) paper jam detection information, (b) paper width detection information, and (c) recording paper passage timing detection information. FIG. 12 is an explanatory diagram showing the relationship between the arrangement of the infrared sensor TS (UR) and the detection of recording paper information performed at the arrangement position.

FIG. 12A shows an arrangement position of an infrared sensor TS (UR) which detects the surface temperature of the heating roller 17A and also detects a jam. The infrared sensor TS (UR) Is disposed at a position facing the heating roller 17A near the downstream side of the nip portion N. At the time of fixing, the surface temperature of the heating roller 17A is detected. When a paper jam occurs and the recording paper P winds around the heating roller 17A and passes through the front surface of the infrared sensor TS (UR), the detection output voltage from the infrared sensor TS (UR) sharply decreases.
The control unit detects that a jam has occurred based on a rapid change in the detection output.

FIG. 12B shows the arrangement and operation of an infrared sensor TS (UR) which detects the surface temperature of the heating roller 17A and also detects the width of the recording paper. By arranging the sensor TS (UR) at a position facing the paper passing portion of the heating roller 17A, the surface temperature of the heating roller 17A at the time of fixing is detected. In addition, during fixing, the temperature of the roller surface is detected while moving the infrared sensor TS (UR) in parallel with the roller axis, so that
The temperature distribution of the heating roller 17A is detected. The width of the recording paper P to be fixed is detected by determining the position where the temperature distribution changes abruptly.

FIG. 12C shows the arrangement and operation of the infrared sensor TS (UR) which detects the surface temperature of the heating roller 17A and also detects the timing of recording paper passing. By arranging the infrared sensor TS (UR) at a position facing the sheet passing portion downstream of the nip portion N of the heating roller 17A, the surface temperature of the heating roller 17A at the time of fixing is detected. Further, during the fixing, the infrared sensor TS (U
By moving R) to a position facing the transfer path of the transfer material, the passage timing of the leading end or the trailing end of the recording paper P is detected. In addition, in order to detect the sheet passing timing satisfactorily, a process is performed on a portion of the transport path facing the infrared sensor TS (UR), and the output in a state where the infrared sensor TS (UR) faces the transport path is performed. By making the voltage largely different from the output voltage when the recording paper is present on the transport path, it is possible to detect the paper passing timing with high accuracy.

According to the present invention, conventionally, information detected by a plurality of temperature sensors can be obtained by one infrared sensor having the above function.

(5) In a fixing device in which a toner image is fixed on recording paper between the heating roller 17A and the pressure roller 47A in the pressed state, the fixing roller is connected between the paper passing portion and the non-paper passing portion of the heating roller 17A. When a temperature difference occurs between the non-sheet passing portions and the temperature becomes excessively high, various obstacles occur in fixing. In the fixing device of the present invention, a cooling unit that cools the temperature rise of the non-sheet passing portion of the heating roller 17A by air cooling, a temperature measurement unit that moves and measures a temperature distribution, and a cooling region variable unit that makes a cooling region variable. The cooling zone is set based on the measurement result of the temperature, and cooling is performed.

(Embodiment 6) In the fixing device of the present embodiment, a movable shielding plate 173a, which is a plate-like member superposed in a bellows shape, is provided as a cooling area varying means, and the movable shielding plate 173a is arranged in a direction perpendicular to the paper passing direction. To move to restrict the flow path.
FIG. 13 is an explanatory diagram of this embodiment.

FIG. 13A is a cross-sectional view of the fixing device of the present embodiment, FIG. 13B is a main part view showing the state of the shielding plate viewed from the paper passing direction, and FIG. It is a principal part figure which shows the state of the shielding board seen from. In this embodiment, the flow of air to be air-cooled flows along the upper and lower heating rollers 17A and the pressing rollers 47A. 173h is a guide plate provided to regulate the air flow and form a ventilation path.

Reference numeral 173g denotes a fan which blows downward by driving a motor. A shielding plate is provided so as to block the air flow. The shielding plate includes a fixed shielding plate 173b and a movable shielding plate 173a for shielding the minimum sheet passing range, and a temperature sensor TS1 for detecting the temperature of the sheet passing portion of the heating roller 17A is fixed to the fixed shielding plate 173b. . Further, a temperature sensor TSS is provided at the tip of the bellows-shaped movable shielding plate 173a, and the movement of the movable shielding plate 173a determines the boundary between the paper passing portion and the non-paper passing portion of the heating roller 17A and performs the non-passing. The temperature distribution of the paper is detected.

The movable shield plate 173a has a screw rod 173
and a motor 173c for driving and rotating a screw rod 173d.
, The bellows-like movable shielding plate 173a moves from the overlapping state forming a wide ventilation range to the state forming a narrow ventilation range. Conversely, the movable shielding plate 173a returns from the extended state to the overlapping state.

In the fixing device of the present embodiment, the movable shielding plate 173a is moved as needed during continuous printing so that the temperature sensor T
When the SS detects the temperature distribution on the surface of the heating roller 17A and detects that the temperature of the non-sheet passing portion is higher than the specified temperature, the controller drives the motor 173c to detect the detected non-sheet passing range. Shielding plate 1 to the position where it is blown to
73a is extended, and the non-sheet passing portion is cooled by the fan 173g.

(Embodiment 7) In the fixing device of the present embodiment, a deflecting plate 174, which is an upright plate-like member, is used as a cooling area varying means.
a, and the deflection plate 174a deflects substantially parallel to the paper passing direction to limit the flow path. FIG. 14 is an explanatory diagram of this embodiment.

FIG. 14A is a cross-sectional view of the fixing device of the present embodiment, and FIGS. 14B and 14C are explanatory views showing a state where the flow path is restricted by deflecting the deflecting plate 174a. is there. In this embodiment, the air flow to be air-cooled flows along the heating roller 17A and the pressure roller 47A located above and below. 174
h is a guide plate provided to regulate this air flow.

Reference numeral 174g denotes a fan that blows air downward by driving a motor. A plurality of deflection plates 17 are provided in this air passage.
4a is provided to deflect the air flow by inclining the deflection plate 174a to restrict the flow path. FIG. 14 (b)
Is the deflection plate 174a for the case where the non-sheet passing area is the widest.
FIG. 14C shows a state in which the deflection plate 174a is deflected to narrow the flow path to a narrow non-sheet passing range.

The deflection angle of the deflection plate 174a is determined by a deflection driving section 174b for regulating the deflection angle. The deflection plate 174a at the left end in the figure determines the flow path to the side plate 174j, and the deflection plate 174a between them determines the middle deflection plate 174a having the function of adjusting the air flow at each location. By setting an appropriate deflection angle,
The non-sheet passing portion can be cooled uniformly, or can be cooled intensively in a range where an excessively high temperature is detected. A temperature sensor TSS is provided at the tip of the deflecting plate 174a, and by oscillating the deflecting plate 174a, the temperature distribution on the surface of the heating roller 17A is detected. Therefore, during the continuous printing operation, the heating roller 1
The temperature distribution on the 7A surface is detected, and the control unit determines the deflection angle of each deflection plate 174a based on the detection result.

When performing continuous printing, the range of the non-sheet passing portion and the degree of temperature rise differ depending on the paper width and paper quality, but the fixing devices of the sixth and seventh embodiments have functions capable of coping with this. Have.

[0084]

According to the first to tenth aspects of the present invention, it is possible to prevent the temperature of the non-sheet passing portion of the surface heat generating roller from becoming excessively high, to avoid the roller from being damaged, and to maintain good fixing. Is provided.

According to the present invention, in addition to the function of detecting the temperature of the roller, the infrared sensor has a function of detecting recording paper information, thereby reducing the number of a plurality of sensors conventionally required. Effect.

According to the fourteenth to twentieth aspects of the present invention, there is provided a fixing device in which even if the paper width or paper quality of the recording paper to be fixed fluctuates, an excessively high temperature portion is not generated correspondingly. Was.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of an image forming apparatus using a fixing device to which the present invention is applied.

FIG. 2 is an explanatory diagram illustrating a structure of a fixing device.

FIG. 3 is an enlarged cross-sectional configuration diagram of a heat ray fixing rotating member of the fixing device of FIG. 2;

4 is a cross-sectional view illustrating an outer diameter and a thickness of a light-transmitting substrate of a rotating member for fixing heat rays of the fixing device of FIG. 2;

FIG. 5 is a control block diagram according to the first embodiment.

FIG. 6 is an explanatory diagram illustrating a situation when fixing recording sheets having different paper sizes according to the first exemplary embodiment.

FIG. 7 is a control block diagram according to a second embodiment.

FIG. 8 is an explanatory diagram showing a situation when fixing recording sheets having different paper sizes according to the second embodiment.

FIG. 9 is a sectional view of a heat ray fixing roller used in a fourth embodiment.

FIG. 10 is a control block diagram according to a fourth embodiment.

FIG. 11 is a graph showing a relationship between a temperature of an object to be measured and a detection output voltage of an infrared sensor.

FIG. 12 is an explanatory diagram showing the relationship between the arrangement of infrared sensors and recording paper information detection.

FIG. 13 is an explanatory diagram of a sixth embodiment.

FIG. 14 is an explanatory diagram of a seventh embodiment.

[Explanation of symbols]

 Reference Signs List 10 photoconductor drum 11 scorotron charger 12 exposure optical system 13 developing device 17 fixing device 17a heat ray fixing roller 17A heating roller 47a, 47A pressure roller 171a translucent substrate 171b heat ray absorbing layer 171c release layer 171d translucent elastic layer 171g Halogen lamp 173a Movable shielding plate 173b Fixed shielding plate 173g Fan 174a Deflection plate 174g Fan P Recording paper TS, TSS Temperature sensor TS (UR) Infrared sensor

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tetsu Haneda 2970, Ishikawa-cho, Hachioji-shi, Tokyo Konica Corporation F-term (reference) 2H033 AA03 BA29 BA31 BA32 CA07 CA16 CA17 CA30 CA32 CA53 3K058 AA34 AA65 AA92 BA18 CA22 CA45 CA70 DA02 GA06

Claims (20)

[Claims] In an image forming apparatus provided with a fixing device having a heating roller provided with a light emitting body inside and a heat ray absorber outside, a temperature detection of a paper passing portion and a non-paper passing portion of the heating roller is performed. It has a temperature detecting means and a cooling area changing means for changing a cooling area by air cooling, and a temperature detecting position and a cooling area of a non-sheet passing portion are made variable according to a paper size to be passed. Image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the temperature detecting unit of the non-sheet passing portion has a plurality of temperature detecting units. 3. The image forming apparatus according to claim 1, wherein the temperature detecting means in the non-sheet passing portion is movable. 4. The image forming apparatus according to claim 1, wherein an area having a width of 0 ± 5 mm with respect to the sheet passing portion is set as a cooling boundary. 5. The image forming apparatus according to claim 1, wherein the cooling power is changed according to a paper type. 6. An image forming apparatus provided with a fixing device having a heating roller provided with a luminous body inside and a heat ray absorber on the outside, and detects a temperature of a paper passing portion and a non-paper passing portion of the heating roller. An image having temperature detecting means and cooling area changing means for changing a cooling area by air cooling, wherein rotation of a heating roller and cooling of a non-sheet passing portion are continued even after a printing operation is stopped. Forming equipment. 7. An image forming apparatus in which a fixing device having a heating roller provided with a light-emitting body inside and a heat ray absorber outside is arranged, the temperature of a paper passing portion and a non-paper passing portion of the heating roller is detected. An image forming apparatus comprising: a temperature detection unit; a cooling region variable unit that changes a cooling region by air cooling; and an air volume control unit that controls a cooling air volume. 8. The image forming apparatus according to claim 7, wherein the wind speed distribution in the cooling area is made uniform. 9. The image forming apparatus according to claim 7, wherein the wind speed is changed according to the temperature of the non-sheet passing portion. 10. The image forming apparatus according to claim 7, wherein a plurality of light emitters having different light emission widths are used as the light emitter. 11. An image forming apparatus having a fixing member and a non-contact infrared sensor disposed in close proximity to each other, the reflectance of the fixing member and the recording paper in an infrared portion are made different, and the temperature of the fixing member and the recording paper are changed. An image forming apparatus for detecting information. 12. An image forming apparatus having a non-contact infrared sensor disposed in proximity to a fixing member, wherein the infrared sensor is movable to detect the temperature of the fixing member and the information of the recording paper from information at a plurality of positions. An image forming apparatus comprising: 13. The printing apparatus according to claim 11, wherein the width or passage of the recording paper is detected from the passing recording paper.
4. The image forming apparatus according to claim 1. 14. A fixing device for fixing a toner image by applying heat and pressure to a transfer material, wherein a cooling means for cooling a temperature rise of a non-sheet passing portion of the transfer material of the heating roller by air cooling,
A fixing device comprising: a temperature measuring unit that moves to measure a temperature distribution; and a cooling region varying unit that varies a cooling region, and sets a cooling region based on a measurement result of the temperature. 15. The fixing device according to claim 14, wherein the temperature measuring unit moves together with the cooling area changing unit. 16. The fixing device according to claim 15, wherein the temperature measuring unit is disposed at an end of the cooling area changing unit. 17. The apparatus according to claim 1, wherein said temperature measuring means is moved during a printing operation to change a cooling area.
A fixing device according to any one of claims 4 to 16. 18. A fixing device for fixing a toner image by applying heat and pressure to a transfer material, wherein cooling means for cooling the temperature rise of the non-sheet passing portion of the transfer material of the heating roller by air cooling has a variable cooling area. A fixing device, comprising: a cooling area changing unit that draws and moves a superposed plate member in a direction orthogonal to a sheet direction to restrict a flow path. 19. A fixing device for fixing a toner image by applying heat and pressure to a transfer material, wherein cooling means for cooling the temperature rise of the non-sheet passing portion of the transfer material of the heating roller by air cooling has a variable cooling area. A fixing device, comprising: a cooling area changing unit that deflects a standing plate-shaped member substantially in parallel with a sheet direction to restrict a flow path. 20. The fixing device according to claim 18, wherein the restriction of the flow path is changed according to a temperature distribution.