JP2002296923A - Transfer fixing device and image forming device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer fixing device and a transfer fixing type image forming device capable of surely restraining a recording sheet from being wrinkled in a transfer fixing stage and performing not only excellent transfer fixing but also image forming free from the deterioration of image quality caused with the wrinkles. SOLUTION: This transfer fixing device 6 is equipped with a heating roll 61 and a pressure roll 62 capable of press-contacting each other in a state where they hold an intermediate transfer belt 50 in between, and performs heating and pressuring by leading the recording sheet into space between the belt 50 and the roll 62 and bringing it into contact with the belt 50. The device 6 is provided with a position adjusting mechanism 9A for adjusting the position of the roll 62 obtained when the roll 62 is separated from the roll 61 by a displacing mechanism 65 to be nearly parallel with the roll 61. The mechanism 9A is mechanism for adjusting a difference (Δα) between axle-to-axle distance (α1 and α2) at both ends of the roll 62 to the roll 61 to be <=100 μm desirably as an absolute value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer fixing device used in an image forming apparatus such as a printer, a copying machine, a facsimile, a multifunction machine, etc., utilizing an electrophotographic system, an electrostatic recording system and the like, and an image using the same. The present invention relates to a forming apparatus.

[0002]

2. Description of the Related Art As an image forming apparatus utilizing an electrophotographic system or the like, an endless intermediate transfer belt (or photoreceptor belt) carrying an unfixed image such as a toner image formed in accordance with image information is recorded. A recording sheet such as paper is brought into close contact with a pair of rolls, heated and pressed, and the unfixed image is cooled and solidified while being kept in contact with the intermediate transfer belt. Japanese Patent Application Laid-Open Nos. Hei 5-107950 and Hei 5-107950 have proposed a simultaneous transfer fixing method (apparatus) for transferring and fixing an unfixed image on a transfer belt to a recording sheet.
No. 19642).

In an image forming apparatus employing this simultaneous transfer fixing method, after the cohesive force between the toners becomes larger than the adhesive force between the toner and the recording sheet, the unfixed toner image is transferred to the intermediate transfer belt (or the intermediate transfer belt). Since the toner image is separated from the photosensitive belt, it is possible to prevent a so-called offset from occurring in which a part of the toner image remains on the intermediate transfer belt or the like. Therefore,
There is no need to use a release oil for preventing offset in the image forming apparatus (it becomes possible to eliminate oil), and the transfer efficiency of the toner is improved, so that the color balance of the image is improved. Further, by solidifying the toner image in a state in which the toner image is brought into close contact with a smooth belt surface such as an intermediate transfer belt, a high-quality image having high gloss and excellent toner transparency can be obtained.

However, on the other hand, in this image forming apparatus, as shown in FIG. 17A, the recording sheet (150) after being heated and pressurized by the transfer / fixing device is almost along the transport direction (B). Many wrinkles (150a)
May occur. In this case, the recording sheet portion (150a) where the wrinkles occur is not limited to the toner image (T) before cooling and solidifying of the toner image (T) as shown in FIG. ) Together with the toner image (T)
Is solidified in a state where it does not adhere to the intermediate transfer member (110) or the like, so that an image obtained after peeling off the recording sheet has an uneven glossiness in which a high gloss portion and a low gloss portion coexist in the image. It can also cause a decline. The low gloss portion at this time is due to the image surface lacking in smoothness as compared with the high gloss portion.

Therefore, the present applicant has also proposed a simultaneous transfer fixing type image forming apparatus for preventing the occurrence of such paper wrinkles and the accompanying deterioration in image quality (Japanese Patent Laid-Open No. 2000-2000). 122441).

[0006] The proposed image forming apparatus is shown in FIGS.
As shown in FIG. 9 a, for example, a device provided with a transfer fixing device 100 in which a pair of rolls 120 and 130 are arranged in the middle of an endless intermediate transfer belt 110 circling in the direction of arrow B so as to sandwich the belt 110. In particular, the nip region N formed between the pair of rolls 120 and 130 is a nip region shaped such that the difference in width in the roll axis direction is reduced. Reference numerals 125 and 135 in the figure denote backup rolls for applying a roll load to the rolls 120 and 130; 140, an image forming unit that forms a toner image according to image information; 150, a recording sheet; A paper path 165 is a conveyance belt for the recording sheet.

More specifically, as shown in FIG. 19B, a nip area N formed by a pair of rolls 120 and 130 is a nip at a central portion in a roll axis direction C perpendicular to the moving direction B of the intermediate transfer belt 110. Width (length) a and nip width (length) at both ends in roll axis direction C
A nip region which satisfies the condition that the ratio a / b (nip shape index) to b is 0.8 or more is adopted.
That is, as shown in FIG. 20, by making the shape of the nip region N a shape having a small difference in width in the roll axis direction C and making the pressure distribution in the nip region uniform, the shape in the roll axis direction C in the nip region N is improved. Transport speed S1, S2
(Or the difference between the transport loads E1 and E2). Thereby, the intermediate transfer belt 110 in the nip region N
The difference between the conveyance speeds of the intermediate transfer belt 110 and the recording sheet 150 is reduced, and the adhesion between the intermediate transfer belt 110 and the recording sheet 150 is conveyed integrally without weakening.
The occurrence of wrinkles on the recording sheet 150 can be suppressed.

[0008]

However, even in such an image forming apparatus of the simultaneous transfer and fixing method, when the recording sheet is wrinkled when passing through the transfer and fixing apparatus, the image quality is also reduced. There is.

According to the study of the present inventors, the occurrence of wrinkling of the recording sheet is particularly caused by the fact that the pair of rolls 120 and 130 in the transfer and fixing device 100 are not supported by the same support frame but are separately supported by separate support frames. If it is supported, furthermore, the roll 120 disposed at a position inside the intermediate transfer belt 110 is supported by a belt unit 115 centered on the intermediate transfer belt, and the unit 115 itself is used as a main body of the image forming apparatus. It has been found that this is likely to occur when the device is attached so that it can be pulled out.

In this case, as shown in FIG. 21 as a dynamic model, the belt unit 115 is slightly hung on the front side by a mounting structure that can be pulled out to the front side (front side of the apparatus) of the belt unit 115, for example. Therefore, the belt unit 11
The roll 120 supported on the fifth side is generally a roll 130
It is in a slightly inclined state. Symbol β in the figure
Is the amount of sag of the axis of the roll 120 with respect to the horizontal, and the amount of sag β is, for example, about several hundred μm. Such a hanging of the front side of the roll 120 causes the support rigidity on the front side of the belt unit 115 to be weaker than that of the rear side due to the above-described pull-out mounting structure, so that the front side sags. Reference numeral 170 in the figure denotes a support structure symbolically indicating that the support rigidity is weak, and indicates a support state in which the support structure is supported via a spring. Also, 1
Reference numeral 80 denotes a support structure symbolically indicating that the support rigidity is strong, and is shown in a support state in which it is firmly fixed. The rigidity of the front side in the case of employing such a drawable mounting structure is, for example, 350 kgf.
/ Mm (about 3500 Nm).

In such an image forming apparatus, the roll 120 hanging down on the front side is
The pressing force J (for example, about 80 kgf / m as a total load) so that the roll 130 is pressed against the intermediate transfer belt 110.
m (about 800 Nm), and the roll 130
It can be lifted until it is almost horizontal with 0 (FIG. 21b). As a result, the roll 12
19b, a nip region N having a substantially uniform width in the roll axis direction is formed as shown in FIG. 19b.

However, in this case, according to the result of numerical analysis, the roll 120 supported by the belt unit 115 having different support stiffnesses on the front side and the rear side receives pressure from the roll 130, so that a gap between the two rolls is obtained. It has been found that a reaction force is generated in the nip region N due to the influence of the reaction force, as shown in FIG. Therefore, due to the friction shear force K generated in the roll axis direction, as shown in FIG.
A shear force (arrow) is also generated between the sheets 50, and the shear force acts in a direction to weaken the adhesive force of the recording sheet 150 to the intermediate transfer belt 110, thereby causing the wrinkles of the recording sheet as described above. It is presumed that it is.

The frictional shearing force K generated in the nip area N between the rolls 120 and 130 is in a state where the roll 120 is lifted up on the front side. It has been found that the same phenomenon occurs even when the relationship is lifted up to the state.

The present invention has been made in view of such circumstances, and an object of the present invention is to reliably suppress the occurrence of wrinkles on a recording sheet in the transfer and fixing step, and to reduce the image quality due to the occurrence of such wrinkles. And a transfer-fixing type image forming apparatus capable of forming a high-quality image without deterioration in image quality due to wrinkling of a recording sheet during transfer fixing. Is to do.

[0015]

According to a first aspect of the present invention, there is provided a transfer / fixing apparatus for carrying an unfixed image, an endless image bearing belt, and an image bearing belt. A first roll disposed at a position on the inner peripheral surface of the image carrier, a second roll disposed at a position on the outer peripheral surface of the image carrier opposed to the first roll, and a rotatable bearing for the first roll A first support for supporting, a second support for rotatably supporting the second roll, and a state in which the second roll presses the second support against the first roll via the image carrying belt. And a displacement mechanism for displacing the recording sheet so as to be separated from the first roll. The recording sheet is guided between the image bearing belt and the second roll pressed against the first roll by the displacement mechanism, and an image is formed. By heating and pressing in close contact with the carrying belt A transfer and fixing device for transferring the unfixed image on the image carrying belt to a recording sheet and fixing the unfixed image on the recording sheet, wherein the position of a second roll when the first roll is separated from the first roll by the displacement mechanism; And a position adjusting mechanism for adjusting the position so as to be substantially parallel to the position.

In this transfer fixing device, the heating at the time of the transfer fixing can be realized by using at least one of the first roll and the second roll as a heating roll, but is not limited thereto. For example, the image bearing belt may be configured to be heated by an electromagnetic induction heating method. Further, from the viewpoint of further improving the image quality of the image obtained by the transfer and fixing, the nip area between the first roll and the second roll (the nip area where the image bearing belt is interposed) is used.
It is preferable to provide a preliminary heating means for heating the unfixed image on the belt in advance by heating at a position on the front side leading to. Further, from the same point of view, the recording sheet that has passed through the nip area of the image carrying belt is conveyed while being kept in close contact with the image carrying belt for a while so that the unfixed image is sufficiently cooled and solidified, and then peeled off. It is preferable to provide a cooling means or a heat radiating means for more efficiently cooling the unfixed image at a position which has been configured or passed through the nip area. The unfixed image is, for example, a toner image formed according to image information by an electrophotographic method, an electrostatic recording method, or the like, but is not particularly limited thereto.

The position adjusting mechanism adjusts the difference in the center distance between both ends of the second roll with respect to the first roll to a very small value (becomes substantially parallel), and is preferable. Is a mechanism for adjusting the difference between the axial distances at both ends to be 100 μm or less in absolute value, preferably 50 μm or less. The difference in the distance between the axes is 100 μm
When the value exceeds, the occurrence of wrinkles on the recording sheet during transfer and fixing cannot be reliably suppressed.

The position adjusting mechanism may be a mechanism for displacing the second support in a direction in which the second roll approaches the first roll and in a direction away from the first roll. Is not particularly limited. Further, when the position adjusting mechanism is capable of automatically adjusting, for example, a distance detector for detecting an axial distance between both ends of the second roll with respect to the first roll, and a detecting device for detecting the distance The mechanism may include a control unit that determines the adjustment amount based on the result, and a drive source that generates a driving force for displacing the second support according to the adjustment amount determined by the control unit.

In such a transfer and fixing device, at least one of the first support and the second support may be attached to the apparatus main body so as to be drawn out. When such a pull-out mounting structure is adopted, an environment in which wrinkles of the recording sheet easily occur at the time of transfer and fixing due to the mounting structure is provided, but the generation of the wrinkles in such an environment is effectively suppressed. can do.

In the transfer fixing device, the second
May have a double structure including a main body that supports and supports the second roll and an auxiliary body that supports the main body via the displacement mechanism. When such a double structure is employed, it is relatively easy to install a position adjusting mechanism and a displacement mechanism in the case where the above-described pull-out mounting structure is employed.

On the other hand, the present invention (second
The image forming apparatus according to the invention) is an apparatus for forming an unfixed image corresponding to image information, and transferring and fixing the unfixed image to a recording sheet to form an image. It is characterized by having any of the devices. In this case, the transfer and fixing of the unfixed image to the recording sheet are performed by a transfer and fixing device. As such an image forming apparatus, for example, an image forming apparatus typified by a printer, a copier, a facsimile, a multifunction peripheral, and the like can be mentioned.

In such an image forming apparatus, an intermediate transfer belt on which an unfixed image is temporarily transferred or a photosensitive belt on which an unfixed image is formed is used as an endless image carrying belt in the transfer and fixing device. Is used.

[0023]

[First Embodiment] FIG. 1 is a schematic view showing a color image forming apparatus to which a transfer fixing device according to a first embodiment of the present invention is applied.

This color image forming apparatus has an image reading device 2 for reading image information in order from an upper side to a lower side on a main body frame 1, and an image processing device 3 for processing the read image information. An image forming apparatus 4 for forming toner images of respective colors of yellow (Y), magenta (M), cyan (C) and black (K) based on the processed image information; An intermediate transfer device 5 that conveys, a transfer fixing device 6 that transfers and fixes the toner image carried on the recording sheet P, and a sheet storage and supply device 7 that stores the recording sheet P and supplies the recording sheet P to the transfer fixing device 6. Is mainly equipped.

The image reading device 2 is a device (scanner) for reading information of a document, or a device for inputting image information transmitted from an external device connected to the image forming apparatus. The imaging device 4 rotates in the arrow direction A,
Four photosensitive drums 11Y, 11M, 11C, 11K on which the four color toner images are distributed and formed exclusively, a charging device 12 for uniformly charging each of the photosensitive drums 11, and an image on each photosensitive drum 11 Latent image writing device 13 for scanning and exposing light corresponding to information to form the four-color electrostatic latent images
And a developing device 14 for storing toners (developers) corresponding to the above four colors for developing the respective latent images, and a primary transfer device 15 for primarily transferring the toner image to (the intermediate transfer belt 50 of) the intermediate transfer device 5. And a cleaning device 16 for cleaning the photosensitive drum 11 after the primary transfer.

The intermediate transfer device 5 transfers the endless intermediate transfer belt 50 to a primary transfer position of the image forming device 3 and a transfer fixing device 6.
Are wound around a plurality of rolls 51a, 51b, 51c, 51d, etc. so as to orbit in the arrow direction B while passing through the transfer fixing position. Among the plurality of rolls 51, a roll 51 a is a drive roll that drives the belt 50 to rotate, 51 b is a peeling roll that supports the belt 50 in a bent state in order to peel the recording sheet P from the belt 50, 51c is a tension roll for applying tension to the belt 50.

The transfer fixing device 6 uses the intermediate transfer belt 50 as one of the components, and includes a heating roll 61 and a pressure roll 62 which are disposed to face each other with the intermediate transfer belt 50 interposed therebetween. Have The heating roll 61 is rotatably supported on the support frame side of the intermediate transfer device 6. On the other hand, the pressure roll 62 is rotatably supported by a support 80 having a double structure including a main body 81 and an auxiliary body 82. Further, in the transfer fixing device 6, preheating plates 55 and 56 for preheating the toner image on the intermediate transfer belt 50 are provided on the inner peripheral surface side of the intermediate transfer belt 50, and the recording sheet P is in close contact with the intermediate transfer belt 50. A cooling plate 57 for actively cooling the toner image transferred and fixed to the toner image is disposed. The pre-heating plates 55 and 56 are provided with a heat source for uniformly heating the inside and the back surface thereof. Cooling plate 57
Is formed of a material such as aluminum which is excellent in heat dissipation and the like. Reference numeral 58 in the figure denotes a sheet-adsorbing charger for charging the recording sheet P to electrostatically adsorb the intermediate transfer belt 50.

The sheet storage and supply device 7 includes a tray 70 for stacking and storing a plurality of recording sheets P, and a sheet feeding mechanism (not shown) for feeding out the recording sheets P stored in the tray 70 one by one. Have been. A sheet conveying path 75 that conveys the recording sheet P between the intermediate transfer belt 50 and the pressure roll 62 of the transfer fixing device 6 is provided between the sheet storage and supply device 7 and the transfer fixing device 6. Reference numeral 76 in the figure denotes the intermediate transfer belt 50 after the transfer and fixing.
Reference numeral 77 denotes a sheet discharge tray which conveys the recording sheet P peeled from the sheet and discharges the recording sheet P outside the apparatus.

In this color image forming apparatus, FIG.
As shown in FIG. 3, the intermediate transfer device 5 and a part of the transfer and fixing device 6 (heating roll 61) are unitized (hereinafter, referred to as a “main unit”), and the entire main unit Y1 is formed. It is attached to the main body frame 1 so as to be able to be pulled out to the front side while being supported by a slide rail or the like. The transfer fixing device 6 is also unitized (hereinafter, referred to as a “subunit”). Similarly, the subunit Y2 is supported by a slide rail (83) or the like with respect to the main body frame 1. It is attached to the front side so that it can be pulled out.

Incidentally, when the main unit or the like is attached so as to be able to be pulled out as in this image forming apparatus,
Front body frame 1a from which the unit is pulled out
The rigidity of the main frame 1b is different from that of the main frame 1b on the opposite side. That is, as shown in FIG. 3, the front body frame 1a has a relatively low rigidity due to a structure in which a plurality of detachable frames 1c, 1d, and 1e are combined, whereas the rear body frame b has such a structure. Rigidity is relatively high without any circumstances. As a result, the entire main unit or the heating roll 61 hangs slightly toward the front. Such a hanging state of the heating roll or the like toward the front side or the rear side also occurs due to a mechanical tolerance or the like.

The transfer fixing device 6 in the color image forming apparatus has a structure as shown in FIGS.

First, the heating roll 61 in the transfer fixing device 6 is formed by laminating a heat-resistant elastic layer 61b such as silicone rubber on a metal hollow roll core 61a, and disposing a heat source such as a halogen lamp inside the hollow of the roll core 61a. The rotating shafts 61c and 61d protruding from both ends of the roll core 61a are rotatably supported (bearings) below the support frame (second support, not shown) on the main unit side. Have been. This heating roll 61 is located on the inner peripheral surface side of the intermediate transfer belt 50. The heating roll 61
Is a pressing roller 62 with the intermediate transfer belt 50 interposed therebetween.
And the heating temperature in the nip region N formed between
So as to be higher than the toner melting temperature (Tm) of the toner image,
It is designed to be heated by a heat source.

On the other hand, the pressure roll 62 in the transfer fixing device 6 has a roll structure in which a heat-resistant elastic layer 62b of silicone rubber or the like is laminated on a metal roll core 62a, and protrudes from both ends of the roll core 62a. The formed rotating shafts 62c and 62d are attached to the main body 81 of the support 80.
It is rotatably supported by a pressing bearing base 64 attached to the side. The pressing bearing base 64 is provided with the pressing roll 6.
2, a pedestal portion 64a elongated in the axial direction, and the pedestal portion 64a
And one end of the pedestal portion 64a in the short side direction is rotatably attached to the support body 81 by a support shaft 64c. A portion immediately below the pressure roll 62 in the short side direction is elastically supported by a pressing spring 64d.

The supporting body 81 on which the pressing bearing base 64 for supporting the pressing roll 62 is installed is a substantially box-shaped housing having a cam receiving portion 81a formed in a part thereof.
One end is rotatably attached to the support auxiliary body 82 by a support shaft 81b, while the other end is supported by a displacement mechanism 65 so as to be vertically displaced. The displacement mechanism 65 is a cam mechanism including a rotary drive shaft 65a installed on the support auxiliary body 82 side and an eccentric cam 65b attached to the drive shaft 65a. The eccentric cam 65b is moved by a predetermined angle. By rotating, the support main body 81 is displaced in the vertical directions G and H. The driving source of the rotary drive shaft 65a is the supporting auxiliary body 8
2 is installed on the bottom surface. Due to the displacement action of the displacement mechanism 65, the pressure roll 62 is in pressure contact with the heating roll 61 via the intermediate transfer belt 50 (the displacement position at this time is referred to as a "pressure contact position") or separated from the heating roll 61 ( The displacement position at this time is referred to as a “separation position”.

On the other hand, the supporting body 81 is connected to the displacement mechanism 6.
The supporting auxiliary body 82 supported via the support 5 is a box-shaped housing having a size capable of housing the entire supporting main body 81 therein.
It is attached movably to the front side via 3.

The position of the pressure roll 62 when the support auxiliary body 82 is separated from the heating roll 61 by the displacement mechanism 65 is adjusted to be substantially parallel to the heating roll 61. A position adjusting mechanism 9 is provided.

The position adjusting mechanism 9 in the first embodiment
Is a mechanism in which the position of the support shaft 81b on the front side of the support body 81 is moved up and down toward the heating roll 61, thereby changing the state of inclination of the entire support body 81 and adjusting the position of the pressure roll 62. ing. In particular, in this position adjusting mechanism 9, the front support shaft 81 of the support body 81 is provided.
As a means for vertically moving the position b, an adjustment mechanism (hereinafter simply referred to as a “screw shaft-slide plate type”) in which a main part is constituted by a screw shaft 90 and a slide plate 91 that moves vertically by rotation of the screw shaft 90. Position adjusting mechanism 9A ").

The screw shaft-sliding plate type position adjusting mechanism 9A is mounted on a rotary driving device 92 having an electric motor whose drive shaft 90 is fixedly mounted on a supporting auxiliary body 82, a drive transmitting mechanism and the like. Also, the slide plate 91
Is in the vertical direction (I, M) with respect to the inner wall of the supporting auxiliary body 82
Is mounted so as to be slidable in a state of being guided by the front side and supporting the lower portion of the front side support shaft 81b from below, and a screw shaft 90 is screwed into a screw shaft screwing hole formed in a predetermined portion thereof. Supported together. The front support shaft 81b is attached to the support auxiliary body 82 so that it can be slightly displaced vertically. Reference numeral 81c in FIGS. 4B and 4C denotes a support shaft on the rear side of the support main body 81.

As shown in FIGS. 4 to 6, the position adjusting mechanism 9A includes rotating shafts 61a, 61b, 62a, 62 at both ends of a heating roll 61 and a pressure roll 62.
An optical distance detector 93 for detecting the inter-axis distances α1 and α2 of b, and a control device 94 for determining an adjustment amount based on the detection result of the distance detector 93 are provided.
The rotation driving device 92 of the screw shaft 90 is driven in accordance with the adjustment amount determined in (1).

The distance detector 94 includes a linear light emitting portion 93a arranged in pairs on both sides of the roll rotating shafts 61a, 61b, 62a, 62b to be detected, and a roll of light Q emitted from the light emitting portion 93a. A light receiving unit 94b that receives light passing between the rotation axes. Further, the control device 94 is configured by a microcomputer or the like, performs a control operation as shown in FIG. 7, determines an adjustment amount in the position adjustment mechanism, and controls the rotation driving device 92 based on the adjustment amount. It is designed to work. At this time, the position adjustment amount is equivalent to the angle of rotation of the electric motor in the rotary drive device 92, and is set and prepared in advance by experiments or the like based on the difference Δα between the shaft distances.
5 (e.g., ROM).

The photosensitive drum 11 in the image forming apparatus 3
Include various inorganic photosensitive materials (Se, a-Si, etc.)
And those made of organic photosensitive materials are used. Further, as the intermediate transfer belt 50 in the intermediate transfer device 5, polyimide, polyester, polyethylene terephthalate,
A belt made of a synthetic resin film such as polyethersulfone, polyetherketone, polysulfone, polyimideamide, or polyamide, and a heat-resistant elastic layer having a volume resistivity adjusted on the belt is used. You.

Next, the operation of the color image forming apparatus having such a configuration will be described.

First, a basic operation related to the image formation will be described. First, a toner image is formed as a first step. In the toner image forming step, in the image forming apparatus 4, after each photosensitive drum 11 is uniformly charged by the charging device 12, the charged photosensitive drum 11 is charged.
A light beam is scanned and exposed from the latent image writing device 13 in response to the image signal output from the image signal processing device 3 based on the image information from the image reading device 2 on the surface of the Is formed. Next, the electrostatic latent images on the respective photosensitive drums 11 are developed with the corresponding color toners accommodated in the developing device 14, respectively, to become toner images of the respective colors. continue,
The toner images of these colors formed by the image forming device 4 are sequentially primary-transferred by the primary transfer device 15 onto the intermediate transfer belt 50 that moves in the direction of arrow B in the intermediate transfer device 5. Thereby, the intermediate transfer belt 50
A multicolor toner image in which a plurality of color toner images are superimposed is formed thereon.

Next, transfer fixing is performed as a second step. In this transfer fixing step, first, the intermediate transfer belt 50
The multicolor toner image transferred and formed thereon is preliminarily heated and melted by the heating action of the heating plates 55 and 56 before reaching the transfer fixing device 6. On the other hand, after the predetermined recording sheet P is sent out from the sheet storage and supply device 7 in accordance with the timing at which this multicolor toner image is conveyed to the transfer and fixing position in the transfer and fixing device 6, It is fed between the intermediate transfer belt 50 and the pressure roll 62. At this time, in the transfer fixing device 6, the pressing roll 62 is previously displaced from the separated position to the press-contact position by the displacement mechanism 65, so that the pressing roll 62 is heated with the intermediate transfer belt 50 interposed therebetween. A nip region N is formed between the nip region N and the nip region N. When the intermediate transfer belt 50 carrying the multicolor toner image and the recording sheet P are supplied in close contact with the nip area N,
The multicolor toner image on the intermediate transfer belt 50 has a melting temperature (T
m) or more and pressurized. Thus, the multicolor toner image on the intermediate transfer belt 50 is softened and melted, penetrates into the recording sheet P, and then is cooled and solidified to be transferred and fixed.

Next, the recording sheet P on which the toner image has been transferred and fixed is conveyed while being kept in close contact with the intermediate transfer belt 50, and after being cooled by the cooling plate 57, is bent by the peeling roll 51b having a small curvature. It is peeled off from the intermediate transfer belt 50 that rotates around the body. At this time, the recording sheet P
The multicolor toner image transferred and fixed to the intermediate transfer belt 50
In a state in which the recording sheet P is in close contact with the recording sheet P, it is cooled by the cooling plate 57 and coagulated and solidified. Further, the recording sheet P is peeled off from the intermediate transfer belt 50 by the strength of the sheet itself at the time when the recording sheet P passes through the peeling roll 51b, and is then discharged to the discharge tray 77 by the sheet conveying and discharging device 76.

As described above, a color image is formed on the recording sheet P. Further, at this time, the surface of the toner image transferred and fixed to the recording sheet P is smoothed to have a high gloss following the surface of the intermediate transfer belt 50.

Next, the position adjusting mechanism 9A of the transfer fixing device 6
Will be described.

First, the position adjusting mechanism 9A in the transfer and fixing device 6 is mainly used in the initial stage of use and when the main or sub unit is pulled out to perform a paper jam removal operation or a maintenance operation. That is, the position adjustment by the position adjustment mechanism 9A is performed when the pressure roll 62 in the transfer and fixing device 6 is separated from the heating roll 61 by the displacement mechanism 65 (separation position). Note that this position adjustment work is performed when the main unit and the like are pushed into the main body frame and mounted.

At the time of the position adjustment, as shown in FIG. 7, first, the heating roll 61 and the pressure roll 6 are controlled by the linear light emitting portion 93a and the light receiving portion 93b of the distance detector 93.
After detecting the inter-axis distances α1 and α2 of the two rotation shafts 61a, 61b, 62a and 62b (step S10), the control device 94 calculates the difference Δ between the inter-axis distances based on the detected information.
α (= α1−α2) is obtained (S11).

Next, it is determined whether or not the absolute value (| Δα |) of the difference Δα between the axes is not more than 100 μm. At this time, the absolute value of the difference Δα between the axes is 100 μm.
If it is determined that the pressure is below, it is considered that the pressure roll 62 is in a state substantially parallel to the heating roll 61, and the position adjustment work ends.

On the other hand, the absolute value of the difference Δα
When it is determined that the pressure roll is larger than 0 μm, the pressure roll 62 is considered not to be in a state parallel to the heating roll 61 but in a tilted state as illustrated in FIG. The adjustment amount is selected and determined (S1
3). That is, the position adjustment amount is selected from the storage data indicating the correlation between the difference Δα and the position adjustment amount. Next, an adjustment operation by the position adjustment mechanism 9A according to the position adjustment amount (the rotation driving device 92 is driven to rotate the screw shaft 90 by a predetermined amount in a predetermined direction, and thereby the slide plate 91 is moved up and down by a predetermined amount. ) Is executed (S14).

For example, the difference Δα between the axes is -100 μm.
If the value is larger on the negative side than m, it means that the front side of the pressure roll 62 is too close to the heating roll 61 hanging down to the front side. It is moved in the direction in which it descends by the fixed amount (arrow direction M). Thereby, the support body 8
As a result, the pressure roll 62 supported by the support main body 81 is similarly lowered on the front side (moved away from the heating roll 61). The state is adjusted so that the front-side inter-axis distance α1 is increased.

On the contrary, the difference Δα between the axes is +100 μm.
If the value is larger on the plus side than m, it means that the front side of the pressure roll 62 hanging down on the front side is too far away, so the slide plate 91
Is moved in a direction (arrow direction I) that rises by a predetermined amount. Thereby, the front side support shaft 81b of the support body 81
Is lifted by the slide plate 91,
As a result, the pressure roll 62 supported by the support body 81 becomes a body whose front side is also lifted (close to the heating roll 61), so that the center distance α1 on the front side is reduced. Adjusted.

After the position adjustment operation by the position adjustment mechanism 9A is performed, the process returns to step S10 again and repeats the above operation in order to confirm whether the position adjustment is correctly performed. In this case, if the position adjustment work has been performed correctly, it is determined in step S12 that the absolute value of the difference Δα between the axes is not more than 100 μm, and the position adjustment work ends. In some cases, after the adjustment operation in step S14 is performed, the position adjustment operation may be completed without reconfirmation.

By performing the position adjusting operation by the position adjusting mechanism 9A, as shown in FIG. 8A, the absolute value of the difference Δα between the shaft distances becomes 100 μm or less, and
2 is substantially parallel to the heating roll 61.

After the position adjustment by the position adjusting mechanism 9A is completed, the supporting body 81 is lifted in the direction of arrow G by the cam operation of the displacement mechanism 65. As a result,
As shown in FIG. 8C, the pressure roll 62 is brought into pressure contact with the heating roll 61 via the intermediate transfer belt 50.
At this time, the heating roll 61 slightly inclined to the front side
Is kept substantially horizontal by the pressure contact of the pressure roll 62. This is because the pressing mechanism 6 of the pressure roll 62
As described above, the rigidity of the front frame 1a of the main body frame 1 is increased due to the pull-out mounting structure of the main unit. This is because the structure has a relationship weaker than the rigidity (see the dynamic model diagram of FIG. 8).

In the transfer and fixing device 6, when the pressing roll 62 is displaced to the pressing position by the displacement mechanism 65, there is a gap between the pressing roll 62 and the heating roll 61 as shown in FIG. A nip region N having a shape with different widths on the front side and the rear side is formed. That is, a press contact portion having a shape in which the width on the front side is smaller than the width on the rear side is obtained.

Through the above-described working steps, the transfer fixing device 6 can be used. Then, after the position of the pressure roll 62 is adjusted by the position adjustment mechanism 9 so as to be substantially parallel to the heating roll 61, the pressure roll 62 is pressed against the heating roll 61 by the displacement mechanism 65. In this case, almost no wrinkles are generated on the recording sheet P along the transport direction (B) during the transfer and fixing. In addition, the resulting image is of high quality without uneven gloss.

Further, in the transfer fixing device 6, before the toner image on the intermediate transfer belt 50 reaches the nip area N between the pressure roll 62 and the heating roll 61,
57, the nip area N has a bad influence on the color development and the fixing strength of the toner image transferred and fixed on the recording sheet P even if the nip area N has the shape shown in FIG. And good results can be obtained.

<Image Forming Test> Next, the first embodiment will be described.
An image was formed using the color image forming apparatus according to (1), and the degree of occurrence of paper wrinkles and uneven gloss at that time was examined.

The conditions of the image forming apparatus are as follows. A photosensitive drum made of an organic photosensitive material was used. As the developer of each color in the developing device 14, a toner of each color having an average particle diameter of 7 μm (weight average molecular weight Mw: 54000, melting temperature Tm: 120 ° C., viscosity η at the melting temperature: 4000 Pas) was used. Further, the exposure conditions and the development conditions when forming the latent image were set such that the toner amount of each color toner image on the recording sheet P was 0.65 mg / cm ^{2 for} each color. Intermediate transfer belt 50
Is prepared by adding a carbon black to a polyimide film and adjusting the volume resistivity to 10 ¹⁰ Ωm.
An endless belt base material having a thickness of 50 μm and a surface layer (volume resistivity: 10 ¹⁴ Ωm, rubber hardness: 30 degrees) made of a silicone copolymer was laminated on an m-endless belt base material.

A heating roll 61 and a pressure roll 62
A straight type having a roll outer diameter of 50 mm in which a 3 mm thick silicone rubber layer was formed on a stainless steel roll core 62a (a form in which the roll diameter is uniform in the axial direction) was used. The total load on the pressure roll 62 by the pressing mechanism 64 was 80 kgf. Further, as the heating plate 56 and the like, an aluminum plate having a thickness of 2 mm and a length of 220 mm in the rotation direction B of the intermediate transfer belt 50 attached to the back surface of a silicon rubber heater was used. The load supporting the main unit in the main body frame 1a on the front side was 350 kgf.

Then, as the recording sheet P, plain paper (JC paper, manufactured by Fuji Xerox Co., Ltd.) having a 10-point average thickness of 100 μm was used. Image formation is performed by rotating the intermediate transfer belt 50 at a speed of 260 mm / sec.
A test image was formed on 100 sheets of plain paper using a vertical line having 200 lines (a line extending in the same direction as the sheet conveying direction B) as a screen. Further, in this test image formation, when the position adjustment by the position adjustment mechanism 9A in the transfer fixing device 6 is performed so that the difference Δα between the axes is within a range of ± 100 μm (Example), Δα is -300 to -150 μm
(Comparative Example 1) and the case where the difference Δα was within the range of 150 to 300 μm (Comparative Example 2).

The recording paper obtained by outputting the test image was observed, and the degree of occurrence of wrinkles and uneven image gloss on the plain paper was evaluated by the following three grades of the naked eye judgment criteria. The acceptable grade in this criterion is “G0”. The result is shown in FIG.
G0: Neither paper wrinkles nor uneven gloss was generated. G1: Plain paper slightly wavy, but no uneven gloss was observed. G2: Both paper wrinkles and gloss unevenness occurred.

As is apparent from the results shown in FIG. 11, the position of the pressing roll 62 is adjusted by the position adjusting mechanism 9A, and the difference .DELTA..alpha.
When the thickness is set to 00 μm or less (Example), the paper wrinkle grades all reach the acceptable level “G0”.

In this case, the heating roll 61 and the pressure roll 6
As shown in FIG. 9, the nip region N between the two has a shape in which the width on the front side is narrower than that on the rear side. As a result, the pressure in the nip area N is smaller on the front side than on the rear side, and as a result, the transport speed S2 on the front side is lower than the rear side on the transport speed S2 when the recording sheet P is transported. A speed difference that the speed is higher than the transport speed S2 is generated. As a result, a force (F) from the front side to the rear side is generated in the nip area N due to the transport speed difference (S1-S2). This force (F) is a force in the opposite direction to the friction shear force (K) generated due to the difference in rigidity of the support structure as described in the section of the related art.
From this, in the case of the present embodiment, the nip area N
The force (F) generated by the difference in pressure distribution and the force (K) generated by the difference in rigidity in the support structure act so as to cancel each other out. Of the recording sheet P at the time of transfer and fixing is suppressed, and as a result, uneven gloss is also suppressed. Conceivable.

On the other hand, in the case where the difference Δα between the axes is -300 to -150 μm as in Comparative Example 1, FIG.
As shown in FIG. 0a, the width on the rear side and the width on the front side are substantially the same. In this case, as described in the section of the related art, it is presumed that wrinkles are generated due to frictional shear force (K) generated due to a difference in rigidity of the support structure. When the difference Δα between the axes is 150 to 300 μm as in Comparative Example 2, as shown in FIG. 10B, the width on the front side is smaller than that in the present embodiment as compared with the rear side. It has a certain shape. In this case, a force (F) from the front side to the rear side is generated as in the case of the embodiment, but this force (F) is generated by a frictional shear force (K) generated due to a difference in rigidity in the support structure. ), It is presumed that wrinkles have occurred.

[Second Embodiment] FIGS. 12 and 13 show a transfer fixing device of a color image forming apparatus according to a second embodiment of the present invention. The transfer fixing device 6 according to the second embodiment is used instead of the transfer fixing device in the color image forming apparatus according to the first embodiment.
In particular, the configuration is the same as that of the transfer fixing device 6 in the first embodiment except that the position adjusting mechanism 9 is changed by applying the following configuration.

That is, the position adjusting mechanism 9 in the transfer fixing device 6 is provided with a pinion gear 95 and a rack gear 96 meshing with the pinion gear 95 as means for vertically moving the position of the front support shaft 81b in the support body 81.
And a slide bearing plate 97 that moves in the vertical direction by the rotation of the pinion gear 95 and has an adjustment mechanism (hereinafter, also simply referred to as a “pinion rack-slide plate type position adjustment mechanism 9B”). It was done.

This pinion rack-slide plate type position adjusting mechanism 9B has a
2 is attached to a rotary drive device 92 fixedly installed. Further, the slide plate 97 is attached so as to be movable in a state guided in the vertical direction (I, M) with respect to the inner wall of the support auxiliary body 82, and a front-side support shaft is provided at a part thereof. A rack gear 96 that meshes with the pinion gear 95 is fixed to other portions while bearing the bearing 81b.

Except for this, the configuration is the same as that of the screw shaft-slide plate type position adjusting mechanism 9A in the first embodiment. For example, also in this position adjusting mechanism 9B, as shown in FIGS. 12 and 13, the rotating shafts 61 at both ends of the heating roll 61 and the pressure roll 62 are provided.
an optical distance detector 93 for detecting inter-axis distances α1 and α2 of a, 61b, 62a and 62b, and this distance detector 93
And a control device 94 that determines an adjustment amount based on the detection result of the control device 94. The rotation driving device 92 of the pinion gear 95 is driven according to the adjustment amount determined by the control device 94.

Then, the position adjusting mechanism 9 of the transfer fixing device 6
The operation associated with B is generally performed by appropriately moving the position of the front support shaft 81b in the support body 81 up and down to set the difference Δα between the axes of the pressure roll 62 and the heating roll 61 to 100 μm or less. Since the position of the roller 62 is adjusted to be substantially parallel to the heating roll 61, the operation is basically the same as that of the position adjusting mechanism 9A of the transfer fixing device 6 in the first embodiment. The only difference is that the movement of the front support shaft 81b in the vertical direction I, M of the support body 81 is performed by the action of the pinion gear 95 and the rack gear 96.

After the position of the pressure roll 62 is adjusted by the position adjusting mechanism 9B so as to be substantially parallel to the heating roll 61, the pressure roll 62 is pressed against the heating roll 61 by the displacement mechanism 65. In this case, similarly to the first embodiment, a nip region N having a shape as shown in FIG. 9 is formed, and the transfer direction (B ) Almost no wrinkles. In addition, the resulting image has high gloss without uneven gloss and no problem in color development and fixing strength. Further, when an image forming test for paper wrinkles and the like in the first embodiment was similarly performed using a color image forming apparatus using the transfer fixing device 6, good similar results were obtained.

[Embodiment 3] FIGS. 14 and 15 show a transfer fixing device of a color image forming apparatus according to Embodiment 3 of the present invention. The transfer fixing device 6 according to the third embodiment is used in place of the transfer fixing device in the color image forming apparatus according to the first embodiment.
In particular, the configuration is the same as that of the transfer fixing device 6 in the first embodiment except that the position adjusting mechanism 9 is changed by applying the following configuration.

That is, the position adjusting mechanism 9 in the transfer fixing device 6 serves as a means for moving the position of the front support shaft 81b in the support body 81 up and down.
An adjustment mechanism (hereinafter simply referred to as simply a slide rail 83) that pivotally attaches a slide rail 83 that supports the slide rail 83 to the main body frame 1 and that moves up and down the free end of the slide rail 83. "Slide rail elevating type position adjusting mechanism 9C").

The slide rail lifting / lowering type position adjusting mechanism 9C has a
A first rail 83a fixed to the second side, and the first rail 8
3a is slidably supported, and its rear end is supported by a support shaft 8
A swing type slide rail composed of a second rail 83b swingably attached to the main body frame 1 via 3c is used. Also, as the lifting device 98, eccentric cams 98a and 98b for raising and lowering the free end (front end) of the second rail 83b in the vertical direction (I, M).
Using a cam mechanism. The two eccentric cams 98a and 98b are fixed to one drive shaft 98c rotatably supported on the body frame 1 side, and one end of the drive shaft 98c is connected to a gear train 99.
a and 99b are connected to a rotary drive device 92 fixedly installed on the body frame 1 side.

Except for this, the configuration is the same as that of the screw shaft-slide plate type position adjusting mechanism 9A in the first embodiment. For example, also in this position adjusting mechanism 9C, as shown in FIGS. 14 and 15, the rotating shafts 61 at both ends of the heating roll 61 and the pressure roll 62 are provided.
an optical distance detector 93 for detecting inter-axis distances α1 and α2 of a, 61b, 62a and 62b, and this distance detector 93
And a control device 94 for determining the adjustment amount based on the detection result of the control device 95. The rotation drive device 92 of the drive shaft 98c is driven in accordance with the adjustment amount determined by the control device 95.

Then, the position adjusting mechanism 9 of the transfer fixing device 6
The operation accompanying C is performed by moving the front end of the slide rail 83 in the vertical direction I, M by the elevating device 98 comprising a cam mechanism.
The support auxiliary body 82 as a whole
Consequently, the support body 81 supported by the support auxiliary body 82
The entire position is moved up and down as appropriate to adjust the difference Δα between the axes of the pressure roll 62 and the heating roll 61 to 100 μm or less so that the position of the pressure roll 62 is substantially parallel to the heating roll 61. It is supposed to. At this time, the elevation device 98 is driven by the distance detector 9 similarly to the position adjustment mechanism 9A of the transfer fixing device 6 in the first embodiment.
3 and the control device 94 to control the rotation drive device 92.

After the position of the pressure roll 62 is adjusted by the position adjusting mechanism 9C so as to be substantially parallel to the heating roll 61, the pressure roll 62 is pressed against the heating roll 61 by the displacement mechanism 65. In this case, similarly to the first embodiment, a nip region N having a shape as shown in FIG. 9 is formed, and the transfer direction (B ) Almost no wrinkles. In addition, the resulting image has high gloss without uneven gloss and no problem in color development and fixing strength. Further, when an image forming test for paper wrinkles and the like in the first embodiment was similarly performed using a color image forming apparatus using the transfer fixing device 6, good similar results were obtained.

[Fourth Embodiment] FIG. 16 shows a color image forming apparatus according to a fourth embodiment of the present invention.
This color image forming apparatus does not employ the intermediate transfer device 5 and includes four photosensitive drums 11Y, 11M, 11C, 11K.
The configuration is the same as that of the image forming apparatus according to the first embodiment except that an image forming apparatus 40 using one photosensitive belt 41 is employed instead of the above.

The image forming apparatus 40 transfers and fixes the endless photosensitive belt 41 to the developing positions of the four developing devices 14Y, 14M, 14C, and 14K that store the toners (developers) corresponding to the four colors. A plurality of rolls 42 a, which circulate in the arrow direction B while passing through the transfer fixing position of the device 6,
It is stretched around 42b, 42c, 42d and the like. Among the plurality of rolls 42, a roll 42a is a drive roll that drives the belt 40 to circulate, a roll 42b is a peeling roll that supports the belt 40 in a bent state in order to peel the recording sheet P from the belt 40, Reference numeral 42c denotes a tension roll for applying tension to the belt 40. The photosensitive belt 41 is charged by one charging device 12, and an electrostatic latent image is written on the charged belt 40 by four latent image writing devices 13. further,
The photosensitive belt 40 is cleaned by a cleaning device (not shown) after the transfer and fixing. As the photosensitive belt 40, for example, a heat-resistant inorganic photosensitive material (Se, a-si, a
-SiC, CdS, etc.).

As the transfer fixing device 6 in this color image forming apparatus, any one of the transfer fixing devices in the first to third embodiments is used in the same manner. In this case, each of the transfer and fixing devices 6 includes the photosensitive belt 4 of the image forming device 40.
1 will be used as one of the components.

Next, an image forming operation by the color image forming apparatus will be described.

First, in the toner image forming step as the first step, in the image forming apparatus 40, after the photosensitive belt 40 is uniformly charged by the charging device 12, the surface of the charged photosensitive belt 40 is charged. The light beam is scanned and exposed from the latent image writing device 13 to form a first color electrostatic latent image. Next, the electrostatic latent image on the photosensitive belt 40 is developed by the developing device 14 containing the corresponding color toner, and is formed as a first color toner image. Hereinafter, similarly, the toner images of the second to fourth colors are formed on the photosensitive belt 40 so as to be sequentially superimposed. This allows
A multicolor toner image in which a plurality of color toner images are superimposed is formed on the photosensitive belt 40.

Next, in the transfer and fixing step as the second step, first, the multicolor toner image transferred and formed on the photosensitive belt 40 is heated before reaching the transfer and fixing device 6 by the heating plates 55 and 56.
Is preliminarily heated and melted by the heating action of On the other hand, a predetermined recording sheet P is fed from the sheet storage and supply device 7 between the photosensitive belt 40 and the pressure roll 62 via the sheet conveying path 75. At this time, in the transfer fixing device 6, since the pressing roll 62 is previously displaced from the separated position to the pressure contact position by the displacement mechanism 65, the heating roll is moved with the pressing roller 62 interposed with the photosensitive belt 40. A nip region N is formed between the nip region N and the nip region N.
Then, when the photosensitive sheet 40 carrying the multicolor toner image and the recording sheet P are supplied in close contact with the nip area N, the multicolor toner image on the photosensitive belt 40 becomes higher than the melting temperature (Tm). , And pressurized.
As a result, the multicolor toner image on the photosensitive belt 40 is softened and melted, penetrates into the recording sheet P, and is then transferred and fixed by being cooled and solidified.

Next, the recording sheet P on which the toner image has been transferred and fixed is conveyed while being in close contact with the photosensitive belt 40, cooled by the cooling plate 57, and then bent by the peeling roll 42b having a small curvature. It is peeled off from the photosensitive belt 40 that rotates around the upper body. At this time, the multicolor toner image transferred and fixed to the recording sheet P is cooled by the cooling plate 57 in a state in which the multicolor toner image is in close contact with the photosensitive belt 40 and coagulated and solidified, and a strong adhesive force is generated between the multicolor toner image and the recording sheet P. . Further, the recording sheet P is peeled off from the photosensitive belt 40 by the stiffness of the sheet itself when passing through the peeling roll 42b, and is discharged toward the discharge tray 77.

Also in this image forming apparatus, the position of the pressure roll 62 is adjusted by the position adjustment mechanism 9A (or 9B, 9C) of the transfer fixing device 6 so as to be substantially parallel to the heating roll 61. Then, the pressing roll 62 is pressed against the heating roll 61 by the displacement mechanism 65. When an image is formed after that, a nip region N having a shape as shown in FIG. 9 is formed between the heating roll 61 and the pressing roll 62 as in the first embodiment. Also, wrinkles along the transport direction (B) hardly occur on the recording sheet P during the transfer and fixing.
In addition, the resulting image has high gloss without uneven gloss and no problem in color development and fixing strength.

[Other Embodiments] In the first to fourth embodiments, the case where the heating roll 61 in the transfer fixing device 6 hangs down to the front side due to the strength of the supporting rigidity has been described. The same applies to the case where the roll 61 is hanging down on the rear side. Further, the position adjusting mechanism 9 (A
The case where the adjustment operations of (C) to (C) are automatically performed by adopting the distance measuring device 93, the control device 94, and the rotation driving device 92 has been described. May be configured to be performed completely manually, or only the driving operation of the adjusting mechanism 9 may be performed manually (semi-manually).

[0089]

As described above, according to the transfer-fixing apparatus of the present invention and the image forming apparatus using the same, first, the occurrence of wrinkles on the recording sheet in the transfer-fixing step is reliably suppressed. Good transfer and fixation without accompanying image quality deterioration can be performed. Finally, it is possible to form a high-quality image excellent in gloss without deterioration in image quality due to generation of wrinkles on the recording sheet during transfer and fixing.

[Brief description of the drawings]

FIG. 1 is a schematic front view showing a color image forming apparatus according to a first embodiment.

FIGS. 2A and 2B show a unit drawer structure of the image forming apparatus shown in FIG. 1, wherein FIG. 2A is a front view and FIG.

FIG. 3 is an explanatory view showing a unit drawer structure and a support structure thereof in FIG. 2;

4A and 4B show a transfer and fixing device in the image forming apparatus of FIG. 1, wherein FIG. 4A is a front view and FIG. 4B is a side view.

FIG. 5 is a schematic top view showing a main part of the transfer fixing device of FIG. 4;

FIG. 6 is an explanatory diagram showing an inter-axis distance at both ends of a heating roll and a pressure roll.

FIG. 7 is a flowchart illustrating a control operation of a position adjusting mechanism in the transfer fixing device.

FIGS. 8A and 8B are dynamic model diagrams showing states of a heating roll and a pressure roll in the transfer fixing device, wherein FIG. 8A is an explanatory diagram showing a state before position adjustment, and FIG. FIG. 3C is an explanatory diagram showing a state at the time of pressing.

FIG. 9 is an explanatory diagram showing a shape of a nip region formed between a heating roll and a pressure roll when pressed against each other after position adjustment, and states of respective acting forces generated in the region.

FIG. 10 is an explanatory diagram showing a shape of a nip region formed between a hot roll and a pressure roll due to a difference in an inter-axis distance, and states of respective acting forces generated in the respective regions.

FIG. 11 is a graph showing the results of an image forming test on paper wrinkles (glossy).

12A and 12B show a transfer fixing device according to a second embodiment, wherein FIG. 12A is a front view and FIG. 12B is a side view.

FIG. 13 is a top view illustrating a main part of the transfer fixing device of FIG. 12;

14A and 14B show a transfer fixing device according to a third embodiment, wherein FIG. 14A is a front view thereof, and FIG. 14B is a side view thereof.

FIG. 15 is a top view illustrating a main part of the transfer fixing device of FIG. 14;

FIG. 16 is a front view showing a color image forming apparatus according to a fourth embodiment.

17A and 17B show paper wrinkles and uneven glossiness that occur in a conventional transfer fixing device, wherein FIG. 17A is a plan view showing the paper wrinkles, and FIG. 17B is an explanatory view showing the process of generating the uneven glossiness.

FIG. 18 is a front view showing a conventional transfer fixing type image forming apparatus.

19A and 19B show a main part of a transfer and fixing device in the image forming apparatus of FIG. 18, wherein FIG. 19A is a perspective view thereof, and FIG. 19B shows conditions of a nip region formed between a heating roll and a pressure roll. FIG.

20 is an explanatory diagram showing a shape of a nip region formed between a heat roll and a pressure roll in the transfer and fixing device in FIG. 19, and states of respective acting forces generated in the respective regions.

FIG. 21 is a dynamic model showing each state of a heating roll and a pressure roll in a conventional transfer fixing device.
(A) is an explanatory view showing a state before pressure welding, and (b) is an explanatory view showing a state at the time of pressure welding.

FIGS. 22A and 22B show respective acting forces generated in a nip region formed between a heating roll and a pressure roll in a conventional transfer fixing device, where FIG. 22A is a plan view and FIG. FIG.

[Explanation of symbols]

6 ... Transfer fixing device, 41 ... Photosensitive belt (image carrying belt), 50 ... Intermediate transfer belt (image carrying belt), 61 ...
Heating roll (first roll), 62: pressure roll (second roll), 65: displacement mechanism, 80: support body (second support body), 81: support body, 82: support auxiliary body, 92: rotation Drive device (drive source), 93: distance detector, 94: control device (control means), P: recording sheet, α1, α2: inter-axis distance.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H033 AA15 BA25 BB03 BB06 BB29 BB30 BB35 BB37 BB38 BE09 CA39 2H035 CA05 CB06 2H078 AA08 BB01 BB12 CC06 DD51 DD53 DD56 2H200 GA12 GA16 GA18 GA24 GA34 GA47 GB30 GB22 GB JA07 JA08 JC04 JC07 JC15 JC16 JC17 JC19 LA22 LA24 LA31 LA38 MA04 MA20 MB04 MC01 PA12 PA22 PB15 PB39

Claims (8)

[Claims] An endless image bearing belt that carries an unfixed image and circulates, a first roll disposed at a position on an inner peripheral surface side of the image bearing belt, and the first roll facing the first roll. A second roll disposed at a position on the outer peripheral surface side of the image carrier,
A first support that rotatably supports the first roll, a second support that rotatably supports the second roll, and a second roll that supports the second support via an image bearing belt. And a displacement mechanism for displacing the first roller to be in a state of being pressed against the first roll and a state of being separated from the first roll. A transfer and fixing device that guides the recording sheet into the image bearing belt, and heats and presses the recording sheet in close contact with the image bearing belt, thereby transferring and fixing the unfixed image on the image bearing belt to the recording sheet. A transfer fixing device comprising a position adjusting mechanism for adjusting the position of the second roll when it is separated from the first roll so as to be substantially parallel to the first roll. 2. The transfer fixing device according to claim 1, wherein the position adjusting mechanism adjusts the difference between the axial distances at both ends of the second roll with respect to the first roll to be 100 μm or less in absolute value. A transfer fixing device characterized by a mechanism. 3. The transfer fixing device according to claim 1, wherein the position adjusting mechanism is a mechanism for displacing the second support in a direction in which the second roll approaches the first roll and in a direction away from the first roll. A transfer fixing device, comprising: 4. The transfer fixing device according to claim 3, wherein the position adjusting mechanism detects a distance between the shafts at both ends of the second roll with respect to the first roll, and a detection of the distance detector. Control means for determining an adjustment amount based on the result;
A transfer source for generating a driving force for displacing the second support in accordance with the adjustment amount determined by the control means. 5. The transfer fixing device according to claim 1, wherein at least one of the first support and the second support is detachably attached to the apparatus main body. Transfer fixing device. 6. The transfer fixing device according to claim 1, wherein the second support is a main body that supports and supports the second roll.
A transfer fixing device having a double structure including an auxiliary body supporting the main body via the displacement mechanism. 7. An apparatus for forming an unfixed image in accordance with image information, and transferring and fixing the unfixed image to a recording sheet to form an image, wherein the image is formed. An image forming apparatus comprising a transfer fixing device. 8. The image forming apparatus according to claim 7, wherein the endless image bearing belt in the transfer fixing device forms an intermediate transfer belt on which an unfixed image is temporarily transferred, or an unfixed image. An image forming apparatus, which is a photoreceptor belt.