JP2001249568A - Fixing device for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of restraining the temperature rise of a holding member, preventing the deterioration of the holding member, realizing the improvement of an operation rate and the reduction of service cost and improving quick-start performance without causing irregular fixing as a quick-start type fixing device. SOLUTION: The length of the heat ray generating part of a heating element is set to be shorter than a distance between the inside ends of the holding member. The fixing device is provided with a heat ray intercepting member intercepting the radiation of a heat ray to the holding member by making the installation width of a heat ray absorption layer nearly coincident with the maximum width of transfer material being a fixing object. By providing a heating roller coming into contact with a fixing roller, the temperature rising speed, the heat capacity and the calorific value per unit time of each single one are optimally set.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus such as a copying machine, a printer, a facsimile, and a multifunction machine having these functions, and a fixing roller used in the fixing device.

[0002]

2. Description of the Related Art Conventionally, a fixing device used in an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile, and a multifunction machine having these functions includes a fixing roller maintained at a predetermined temperature, an elastic roller, A heat roller fixing method, in which a transfer material on which an unfixed toner image has been transferred is heated while being nipped and conveyed by a pressure roller having a layer and pressed against the fixing roller, is a monochrome machine from a low-speed machine to a high-speed machine. It is widely used in everything from color machines to color machines.

However, in a conventional heat roller fixing type fixing device, it is necessary to heat a fixing roller having a large heat capacity when heating a transfer material or toner, so that the power saving effect is poor and disadvantageous in power saving. In addition, there is a problem that it takes time to warm up the fixing device at the start of image formation, and the time (warming-up time) until image formation starts is lengthened.

In order to solve this problem, a fixing roller having a light-transmitting elastic layer provided outside a cylindrical light-transmitting substrate and a heat ray absorbing layer outside the fixing roller is employed, and is provided inside the light-transmitting substrate. After absorbing the heat rays from the halogen lamp
A fixing device and a method of a quick start system for fixing a toner image on a transfer material by heating and pressing are disclosed in
Nos. 6741 and 57-82240 and 57-82
These are disclosed and known in JP-A-102736, JP-A-57-102741, and JP-A-11-327342.

[0005] FIG. 9 is a plan sectional view of a fixing roller 71 and a pressure roller 72 showing a conventional example of a fixing device of the above-described quick start system. Regarding the operation and configuration of each unit shown in FIG. 9, the same members are given the same numbers in the first embodiment of the present invention shown in FIG. 4, and the details will be described later.

As shown in FIG. 9, in a conventional fixing device, a light transmitting base 71a is provided with a bearing 7 as a holding member.
1d, which is detachably fitted and rotates as a driven roller of a pressure roller 72 driven to rotate by a gear 78 meshing with a reduction gear connected to driving means (not shown). The toner image is fixed by heating and pressing the toner image on the transfer material at a nip formed by contact with the heat ray absorbing layer 71c and the translucent elastic layer 71b.

The fixing roller 71 has a configuration in which a light-transmitting elastic layer 71b made of transparent silicon rubber and a heat ray absorbing layer 71c are sequentially laminated on the outer peripheral surface of a hollow cylindrical light-transmitting substrate 71a. In the fixing roller 71, a halogen heater 73 is provided.
Is emitted and absorbed by the heat ray absorbing layer 71c through the light transmitting base 71a and the light transmitting elastic layer 71b,
The heat ray absorbing layer 71c raised to a high temperature is pressed against the toner image on the transfer material. The pressure roller 72 is obtained by coating an outer peripheral surface of a hollow cylindrical core metal member 72a made of a metal such as an aluminum alloy with an elastic member 72b such as silicon rubber.

[0008]

However, as shown in FIG. 9, in the conventional fixing device, the length of the heat ray generating portion 73b of the halogen heater 73 as a heating element is substantially equal to the length of the fixing roller in the rotation axis direction. Was set to
There is a problem that the generated heat rays are directly radiated to the inner ring of the bearing 71d as a holding member, and the bearing 71d is exposed to a high temperature. In addition, the heat ray absorbing layer 71c formed up to the vicinity of the bearing 71d is used when the fixing device operates.
Since the temperature rises to about 00 ° C., the generated heat is transmitted by heat conduction to the bearing 71d via the heat ray absorbing layer 71c, the translucent elastic layer 71b, and the translucent base 71a, and the temperature of the bearing 71d is further reduced. There was a problem of rising. That is, since the bearing 71d or the like containing oily lubricating oil is usually used as the holding member, if the holding member rises to a high temperature during the operation of the fixing device, the evaporation of the lubricating oil component contained therein is accelerated, and In the meantime, the holding member will deteriorate.

For this reason, the bearing 7 as a holding member
If the life of 1d etc. is shortened and needs to be replaced early,
Alternatively, maintenance work such as frequent lubrication is required, leading to an increase in maintenance cost, which is a problem.

On the other hand, in the conventional fixing device, the fixing roller 71 absorbs the heat rays radiated from the halogen heater 73 by the heat ray absorbing layer 71c and generates heat from the surface. The heat generated in the layer 71c is transmitted and absorbed toward the pressure roller 72 having a large heat capacity, and heat is easily accumulated inside the pressure roller 72. Therefore, until the surface temperature of the fixing roller 71 reaches the feasible fixing temperature. , Ie, the warm-up time becomes long, and it is difficult to obtain a desired quick start performance.

Since the elastic member 72b of the pressure roller 72 has a low thermal conductivity in the longitudinal direction of the surface, a temperature distribution is generated on the surface of the pressure roller 72 during fixing of the transfer material. Therefore, when the fixing of the transfer material is continuously performed,
Alternatively, when fixing of transfer materials having different sizes is performed, uneven fixing in the horizontal direction of the image occurs, which is a problem.

In order to solve the above-mentioned problem of the pressure roller 72, a heat roller provided with a heat generator therein is used in place of the pressure roller 72, and the temperature of the heat roller is positively increased during warm-up. However, the above problem has not yet been effectively solved.

The present invention has been made in view of the above-mentioned problems of the related art, and a first object of the present invention is to provide a fixing device of the above-mentioned quick start system, wherein the fixing device is held inside a fixing roller. By setting the length of the heat ray generating section of the heating element shorter than the distance between the inner ends of the holding member that holds both ends of the fixing roller, the temperature rise of the holding member is suppressed, and the deterioration of the holding member is prevented. It is an object of the present invention to provide a fixing device capable of improving the operation rate and reducing the service cost.

A second object of the present invention is to provide a fixing device of the above-mentioned quick start system, wherein the installation width of the heat ray absorbing layer is made substantially equal to the maximum width of the transfer material to be fixed, and A fixing device that suppresses the temperature rise of the holding member, prevents the deterioration of the holding member, improves the operation rate and reduces the service cost by providing a heat ray blocking member that blocks radiation of heat rays to the holding member inside. It is intended to provide.

Further, a third object of the present invention is to provide a fixing device of the above-mentioned quick start system, wherein a heating roller is provided in contact with the fixing roller, and a heating rate, a heat capacity, and a heating value per unit time are optimized independently. It is an object of the present invention to provide a fixing device capable of improving quick start performance without causing fixing unevenness.

[0016]

In order to achieve the first object, the fixing device according to the first aspect of the present invention is arranged such that the fixing device is provided outside of a cylindrical light-transmitting substrate having a light-transmitting property. A fixing roller provided with a heat ray absorbing layer that absorbs heat, a holding member that holds both ends of the fixing roller, and a heating element that is held inside the fixing roller and generates the heat ray, and a toner on a transfer material is provided. In a fixing device for fixing an image to the transfer material, a length of a heat ray generating portion of the heating element in a rotation axis direction of the fixing roller is shorter than a distance between inner ends of the holding member.

According to a second aspect of the present invention, there is provided a fixing device according to the first aspect, wherein the heating element is a halogen lamp.

According to a third aspect of the present invention, there is provided a fixing device according to the first or second aspect, wherein the holding member is a bearing. And

According to a fourth aspect of the present invention, there is provided a fixing device according to any one of the first to third aspects.
The fixing device according to any one of claims 1 to 3, wherein a heat insulating member is provided between the fixing roller and the holding member.

According to a fifth aspect of the present invention, there is provided a fixing device according to the fifth aspect, wherein the heat rays absorb the heat rays outside a cylindrical light-transmitting substrate having a light-transmitting property with respect to the heat rays. A fixing roller provided with an absorbing layer, a holding member for holding both end portions of the fixing roller, and a heating element held inside the fixing roller to generate the heat rays, wherein the toner image on the transfer material is transferred to the transfer roller. In a fixing device for fixing to a material, an installation width of the heat ray absorbing layer in a longitudinal direction of the fixing roller substantially coincides with a maximum width of the transfer material to be fixed.

According to a sixth aspect of the present invention, there is provided a fixing device according to the fifth aspect, wherein the heat ray absorbing layer has an end portion closer to an end than the installation width. A heat ray blocking member for blocking the heat ray is provided inside the light transmitting substrate.

In order to achieve the second object, a fixing device according to a seventh aspect is characterized in that, in the fixing device according to the sixth aspect, the heat ray blocking member reflects the heat ray. I do.

In order to achieve the third object, the fixing device according to the eighth aspect of the present invention provides the fixing device, wherein the first heat ray is transmitted outside the cylindrical light-transmitting substrate. A heat ray absorbing layer that absorbs heat rays of the first type;
A fixing roller provided with a first heat generating member for generating a heat ray, and a heat generating roller provided with a second heat generating member for generating a second heat ray inside a cylindrical metal base; In a fixing device in which a toner image on a transfer material is fixed to the transfer material at a nip formed by contacting a roller and the heat generation roller, a surface heating rate St of the fixing roller alone and a surface temperature increase of the heating roller alone The speed Sh may be set to be substantially the same, or the surface heating speed Sh of the heating roller alone may be set to a value greater than the surface heating speed St of the fixing roller alone.

According to a ninth aspect of the present invention, there is provided a fixing device according to the ninth aspect, wherein the heat capacity Ct of the fixing roller alone is equal to that of the heating roller alone. It is characterized by being larger than Ch.

In order to achieve the third object, the fixing device according to the tenth aspect is the fixing device according to the eighth or ninth aspect, wherein the first heating element has a unit time per unit time. Is characterized in that the heat value Qt is larger than the heat value Qh per unit time of the second heat generator.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus equipped with a fixing device according to the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of a color printer which is an image forming apparatus equipped with the fixing device of the present invention.

In this color printer, a flexible endless belt-shaped photosensitive member (hereinafter, referred to as a photosensitive member) 1 serving as an image carrier is provided.
, Four sets of scorotron chargers (hereinafter referred to as chargers) 2Y, 2M, 2C, 2K, four sets of image exposure devices 3
Y, 3M, 3C, 3K, four sets of developing units 4Y, 4M, 4
The image forming units C and 4K (four sets as shown) are arranged in tandem. The illustrated image exposure apparatus 3
Y, 3M, 3C, and 3K use a laser beam scanning optical device.

The photosensitive member 1 is stretched around a driving roller 11, a lower roller 12, and an upper roller 13, and a tension roller 14
And is rotated clockwise as shown in the drawing while being locally brought into contact with the backup member 15 provided on the inner peripheral surface. The backup member 15 is in contact with the back surface of the photoreceptor 1 and develops the developing areas of the developer carriers 41Y, 41M, 41C, and 41K of the developing units 4Y, 4M, 4C, and 4K and the image exposure devices 3Y, 3M, 3C, and 4K. The photoconductor 1 is regulated at the 3K image forming position.

At the start of image recording, a drive motor (not shown) is rotated to rotate the photoreceptor 1 clockwise through a drive roller 11 by the charging operation of the charger 2Y. Application of the potential to 1 is started. Photoconductor 1
Is the first in the image exposure apparatus 3Y after the potential is applied.
Exposure is started by an electrical signal corresponding to the color signal of the photoconductor 1, ie, the yellow (Y) image signal, and the rotation (sub-scanning) of the photoconductor 1 causes the photosensitive layer on the surface to correspond to the yellow (Y) image of the developed image. An electrostatic latent image is formed. The developing device 4Y reversely develops the latent image in a non-contact state on the developer carrying member 41Y by the developing device 4Y to form a yellow (Y) toner image.

Next, the photoreceptor 1 is further provided with a potential on the yellow (Y) toner image by the charging action of the charger 2M, and is converted into a second color signal of the image exposure device 3M, that is, an image signal of magenta (M). Exposure is performed by the corresponding electric signal, and a magenta (M) toner image is formed on the yellow (Y) toner image by non-contact reversal development by the developing device 4M.

By the same process, a cyan (C) toner image corresponding to the third color signal is further formed by the charger 2C, the image exposure device 3C, and the developing device 4C. Further, a black (K) toner image corresponding to the fourth color signal is sequentially superimposed and formed by the charger 2K, the image exposure device 3K, and the developing device 4K, and is formed on the peripheral surface within one rotation of the photoconductor 1. A color toner image is formed.

The color toner image formed on the peripheral surface of the photoreceptor 1 reaches the transfer area after the potential of the attached toner is adjusted by the charger 2F. From the paper feed cassette 51 or the manual paper feed table 53 of the paper feed device 5,
The transfer material P sent out by the registration rollers 2 and 54 and conveyed to the registration roller pair 55 is fed by the driving of the registration roller pair 55 in synchronization with the passage of the toner image area on the photoconductor 1, and the lower portion of the drive roller 11 The toner image is transferred by the transfer means 6 disposed opposite to the toner image.

The transfer material P on which the toner image has been transferred is separated from the peripheral surface of the photoreceptor 1 and then conveyed to the fixing device 7. The toner image is melted by the fixing device 7 and fixed on the transfer material P. After the completion of the fixing process, the transfer material P is conveyed by a pair of paper discharge rollers 81, 82, and 83 and discharged to a paper discharge tray 84 provided at an upper portion.

On the other hand, the photosensitive member 1 from which the transfer material P has been separated is cleaned by removing the residual toner by the cleaning blade 91 of the cleaning device 9. When the formation of the toner image of the next original image is subsequently performed, the pre-charging static eliminator 92 exposes the photoconductor surface of the photoconductor 1 to remove the previous charge.

FIG. 2 is a cross-sectional view showing the internal structure of the fixing device 7, and FIG. 3 is an enlarged cross-sectional view of a main part of the fixing device 7 including a fixing roller 71, a pressure roller 72, and a halogen heater 73. FIG. 4 is a plan sectional view of the fixing device according to the first embodiment of the present invention.

As shown in FIG. 2, the fixing device 7 includes a fixing roller 71, a pressure roller 72, and a halogen heater 7 serving as a heat source.
3, cleaning roller 74, cleaning pad 7
5, an oil applying means 76, a paper discharge roller 77 and the like. Further, the cleaning roller 74 includes a rotating shaft 74.
a and an elastic member 74b. Both ends of the rotating shaft 74a are fitted to bearing members (not shown) held on the left and right fixing device body side plates 70, and are rotatable. Elastic member 74b
Is a roller made of a heat-resistant resin such as foamed silicone rubber.

The translucent substrate 71a shown in FIG. 3 is a hollow cylindrical body made of heat-resistant glass or heat-resistant resin that transmits heat rays such as infrared rays or far infrared rays emitted from a halogen heater 73 as a heating element. In the first embodiment of the present invention shown in FIG. 4, an outer diameter 2
A hollow cylindrical body made of Pyrex glass (manufactured by Corning, USA) having a thickness of 8 mm and a thickness of 1.5 mm is used.

The light-transmitting elastic layer 71b is made of a light-transmitting substrate 71a.
Is a transparent silicon rubber layer (in the present embodiment, the thickness is set to 2.5 mm) formed on the outer peripheral surface of. Heat ray absorption layer 71
c is an outermost layer in which the outer peripheral surface of the translucent elastic layer 71b is coated with perfluoroalkoxy (PFA) containing carbon (the thickness is set to 0.05 mm in the present embodiment). The surface hardness of the thus configured fixing roller is 80 ° when measured with a load of 1 kg using an Asuka C-type rubber hardness meter.

In order to prevent the fixing roller 71 from shifting in the longitudinal direction, the position regulating side plate 70a is screwed to the fixing device main body side plates 70 on both sides by screws (not shown). The position regulating side plate 70a is also used as heating element holding means for holding the halogen heater 73,
3 having a small hole for holding the lead wire 3 and passing the lead wire 73a
0c is a position regulating side plate 70a on both sides by screws (not shown).
, The halogen heater 73 is held in the fixing roller 71.

In the above configuration, the heat rays emitted from the halogen heater 73 pass through the light-transmitting base 71a and the light-transmitting elastic layer 71b and are absorbed by the heat ray absorbing layer 71c. Is formed.

The pressure roller 72 is formed by forming an elastic layer 72b of silicon rubber or the like on the outer peripheral surface of a hollow cylindrical core member 72a made of a metal such as an aluminum alloy. As shown in FIG. 4, both ends of the core member 72a are rotatably supported by bearings 72c. The bearing 72c is urged by a spring 72d,
The pressure roller 72 is pressed against the fixing roller 71.

As shown in FIG. 4, both ends of the translucent base 71a are fitted to bearings 71d as holding members for the fixing roller 71 via heat insulating sleeves 71f described later, and are rotatable. The bearing holding member 71e is fitted and fixed to the bearing holding member 71e, and is screwed to the fixing device main body side plate 70 by a screw (not shown). Here, the translucent base 71a is detachably fitted to a heat insulating sleeve 71f described below so that the translucent base 71a can be cleaned or replaced at the time of maintenance as needed.

A gear 78 is fitted and fixed to the left end of the core member 72a of the pressure roller 72 in FIG.
Is meshed with a reduction gear connected to driving means such as a motor (not shown), and drives the pressure roller 72 to rotate. Along with this, the translucent base 71a is driven to rotate in the direction of the arrow shown in FIG.

Here, in the first embodiment shown in FIG. 4, the inside of the halogen heater 73 is constituted by a heat ray generating part 73b for generating a heat ray and a non-heat ray generating part 73c as a conductor which does not generate a heat ray. Length 73b of generating part 73b
w is a bearing 7 installed at both ends of the fixing roller 71
It is set to be shorter than the distance 71dw between the inner ends of 1d. For this reason, the heat ray generated in the heat ray generation part 73b does not directly radiate to the inner ring of the bearing 71d,
The generated heat rays are efficiently radiated to the heat ray absorption layer 71c. The non-heat generating part 73c is connected to the external lead 7
3a, power is supplied from a power supply circuit (not shown) to the heat ray generator 73b through an external lead wire 73a.

A heat insulating sleeve 71f as a heat insulating member is fitted to both ends of the light transmitting base 71a, and a bearing 71d is fitted to the outer peripheral surface of the heat insulating sleeve 71f and fixed by bonding. Therefore, the heat generated in the heat ray absorbing layer 71c which is formed up to the vicinity of the bearing 71d and rises to about 200 ° C. during the operation of the fixing device is transferred to the bearing 71d via the translucent elastic layer 71b and the translucent base 71a. The transmitted heat conduction can be reduced by the heat insulating sleeve 71f, and the temperature rise of the bearing 71d is further prevented.

As a material of the heat insulating sleeve 71f, for the above purpose, for example, the thermal deformation temperature under a load of 18.6 [kg / cm ² ] defined by JIS-K7207 is 236 [° C.] 0.3 [W / m · K]
It is preferable to use 40% glass reinforced polyphenylene sulfide (PPS).

As described above, according to the first embodiment of the fixing device according to the present invention, the length 73 bw of the heat ray generating portion 73 b is changed to the inner end portion of the bearing 71 d installed at both ends of the fixing roller 71. Since the heat insulating sleeve 71f is set to be shorter than the distance 71dw between the heat radiation absorbing layers 71c and reduces heat conduction transmitted to the bearings 71d, the lubricating oil evaporates as the temperature of the bearings 71d rises. -Solidification can be effectively prevented.

Next, FIG. 5 shows a plan sectional view of a fixing device according to a second embodiment of the present invention, which will be described in detail.
The same components as those in the first embodiment are given the same reference numerals, and overlapping descriptions will be omitted.

In FIG. 5, the installation width 71cw of the heat ray absorbing layer 71c in the longitudinal direction of the fixing roller is set to substantially coincide with the maximum width of the transfer material P to be fixed through the nip portion. For example, A4 size (length 297mm
When the vertical width of the transfer material P (width 210 mm) is set as the maximum width that can be fixed, the installation width 71 cw is set to the vertical width 2 of the transfer material.
Approximately 97 mm. In the second embodiment shown in FIG. 5, a margin of 3 mm is provided and the installation width 71cw is set to 300 mm in consideration of a slight shift of the transfer material or the fixing roller in the rotation axis direction of the fixing roller. .

A heat ray blocking member 70g is provided at both ends of the halogen heater 73 held inside the fixing roller. The heat ray blocking member 70g has a conical shape that covers both ends of the halogen heater 73 outside the installation width 71cw of the heat ray absorbing layer 71c, has a flange at the top of the cone, and spot-welds the flange with a screw or a screw. By fixing, it is fixed to the lid plate 70c. The heat ray blocking member 70g is made of aluminum material, and its inner peripheral surface is mirror-finished.
The heat rays radiated from b to the end of the fixing roller are reflected toward the inside of the fixing roller. The material of the heat ray blocking member 70g is not limited to aluminum, but may be any material having heat resistance, such as an iron plate, heat-resistant glass, or heat-resistant plastic. Those having a mirror finish such as are preferred.

As described above, according to the second embodiment of the fixing device according to the present invention, the installation width 71cw of the heat ray absorbing layer 71c substantially coincides with the maximum width of the transfer material P to be fixed. Because of the limitation, generation of high heat near the bearing 71d can be prevented,
The temperature rise of d is moderated, and the evaporation and solidification of the lubricating oil accompanying the temperature rise of the bearing 71d can be prevented.

Further, a heat ray blocking member 70g is provided at both ends of the halogen heater 73 to block the heat ray radiated directly to the bearing 71d and to reflect the light toward the inside of the fixing roller, so that the temperature rise of the bearing 71d is further reduced. In addition, it is possible to prevent the lubricating oil from evaporating and solidifying due to a rise in the temperature of the bearing 71d, and most of the reflected heat rays are absorbed by the heat ray absorbing layer 71c, and the heat rays generated in the heat ray generating section 73b. Can effectively increase the utilization efficiency.

Next, FIG. 6 is a plan sectional view of a fixing device according to a third embodiment of the present invention, and FIG. 7 is a cross sectional view of a fixing roller and a heat generating roller. The same components as those in the first embodiment are given the same reference numerals, and overlapping descriptions will be omitted.

In FIG. 6, a driving gear 178 fitted and fixed to the left end of the translucent base 71a meshes with a reduction gear connected to driving means (not shown) to rotate the fixing roller 71. are doing. Further, inside the fixing roller 71, a first halogen heater 173 as a first heating element for generating a first heat ray is provided, and the fixing roller 71 capable of rapid heating is formed.

On the other hand, the heating roller 17 as a pressing roller
Numeral 2 is rotatably supported at both ends of a cylindrical metal base 172a by bearings 172c, urged in the direction of the fixing roller 71 by a spring 172d, and pressed against the fixing roller 71. Also, the second inside of the heat generating roller 172 is
A second halogen heater 273 is provided as a second heating element for generating a heat ray, and a heating roller 172 capable of rapid heating is formed.

In the above configuration, with the rotation of the fixing roller 71, the heating roller 172 rotates as a driven roller of the fixing roller 71, and the metal base 172a of the heating roller 172 is rotated.
The toner image on the transfer material is heated and heated at the nip formed by the contact between the heat-absorbing layer 71c and the heat-absorbing layer 71c on the translucent elastic layer 71b.
The toner image is fixed by pressing.

In the above-described image forming apparatus, since the temperature of the fixing roller 71 is usually lowered to the normal temperature before the power is turned on, a warm-up time is required after the power is turned on to raise the temperature of the fixing roller 71 to a fixing temperature. This is necessary, and image formation is prohibited until the warm-up is completed.

The surface temperature of the fixing roller 71 is
At 1 s, the surface temperature of the heat generating roller 172 is detected by a temperature sensor 172 s, and the detection result is sent to a control circuit (not shown). After the temperature of the fixing roller 71 rises to a temperature at which fixing can be performed, a power supply circuit (not shown) for supplying power to the first halogen heater 173 and the second halogen heater 273 is operated based on the detection results of the temperature sensors 71s and 172s. A control circuit (not shown) controls the on / off control to keep the fixable temperature of the nip portion constant. Each of the temperature sensor 71s and the temperature sensor 172s includes a thermocouple, a thermistor, or the like, and preferably uses a non-contact radiation temperature sensor.

Here, the heating rate at which the temperature of the nip portion rises during the warm-up time is Sn,
The surface heating speed of the fixing roller 71 alone when it is assumed that the heating roller 172 does not contact the heating roller 172 is St, and the surface heating speed of the heating roller 172 alone when the heating roller 172 is not in contact with the fixing roller 71 is St. Sh
Is defined.

Under the above definition, in the third embodiment shown in FIG. 6, when St ≒ Sh is set (that is, St ≒ Sh).
Is substantially equal to Sh), the nip temperature increases while the surface temperature of the fixing roller 71 and the surface temperature of the heat generating roller 172 remain substantially the same. For this reason,
Since the heat generated in the heat ray absorbing layer 71c during the warm-up time is transmitted and absorbed toward the heat generating roller 172, a decrease in the temperature rising speed Sn of the nip portion is prevented.
The temperature of the nip is raised while maintaining the relationship of ≒ St ≒ Sh, and the warm-up time is effectively reduced.

Next, when Sh> St is set (that is,
FIG. 8 is a graph showing how the surface temperature of the fixing roller 71 alone, the surface temperature of the heating roller 172 alone, and the temperature of the nip increase with time when Sh is set to be larger than St).

In FIG. 8, T1 indicates the time required for the temperature of the nip to reach the fixing-possible temperature (180 ° C. in the third embodiment), and T2 indicates the time T
1 indicates a time period in which the temperature of the nip portion is maintained at a fixing-possible temperature after the lapse of 1 and heat is accumulated in the fixing roller 71. T2 is
This is a time required for heat storage of the roller in order to prevent a sharp drop in the temperature of the nip portion when the transfer material P is fixed, and the warm-up is completed when T1 + T2 elapses after the power is turned on, thereby enabling image formation. T3 indicates a time when the surface temperature of the heating roller 172 alone reaches the feasible fixing temperature when it is assumed that the heating roller 172 does not contact the fixing roller 71.
Indicates the time when the surface temperature of the fixing roller 71 alone reaches the feasible fixing temperature when it is assumed that the fixing roller 71 does not contact the heat generating roller 172.

As shown in FIG. 8, when Sh> St is set, the increase in the surface temperature of the heat generating roller 172 actively contributes to the increase in the temperature of the nip portion, so that Sn becomes larger than St and T1 Is shortened compared to T4. In other words, the temperature rise curve of the nip portion shown by the solid line is located between the surface temperature rise curve of the heating roller 172 alone and the surface temperature rise curve of the fixing roller 71 alone shown by the broken line. By setting Sh and St in this way, the warm-up time can be further reduced.

In the third embodiment shown in FIG.
T3 = 45 [sec. ], T4 = 55 [sec. ], And Sh = 4 [° C./sec. ], St = 3.27 [° C.]
/ Sec. ]. In this case, the heating roller 172
And the surface temperature rise speed ratio Sh / St of the fixing roller 71 is 1.22, and the value of Sh / St is preferably in the range of 0.8 to 1.5, and is 1.0 to 1.3. Is preferably in the range of Under the above conditions, the temperature rise time T1 of the nip is T1 = 50 [sec. ]
T2 is 10 [sec. ] Is set. T2 is 0.
It is preferable to set a value within a range of 1 × T1 to 0.3 × T1.

The surface heating rate S of the fixing roller 71 alone
t, the surface heating rate Sh of the heating roller 172 alone
It is effective to set the heat capacity Ch of the heat generating roller 172 alone to be smaller than the heat capacity Ct of the fixing roller 71 alone in order to set the heat capacity Ch to be large. Therefore, in the third embodiment shown in FIG. 6, an aluminum material is used for the metal base 172a of the heat generating roller 172, and the thickness at the nip portion is processed to a thickness of 1 mm.

In this case, since the nip portion of the heat roller 172 is made of metal, the thermal conductivity on the roller surface is improved, so that the temperature distribution in the longitudinal direction of the shaft is made uniform, and the occurrence of fixing unevenness occurs. Is prevented. Further, since the surface has high hardness, the separability of the transfer material P after fixing is improved. Further, a hard and thin elastic layer (preferably 50 μm or less) such as a PFA tube can be provided on the metal base 172a in order to make the transfer material P easily compatible with the transfer material P. In this case, the above effect is maintained.

Further, when the above setting is made, the heat capacity Ct of the fixing roller 71 alone becomes much larger than the heat capacity Ch of the heating roller 172 alone. Halogen heater 1
The heat generation amount Qt per unit time of 73 needs to be set to be larger than the heat generation amount Qh per unit time of the second halogen heater 273. By setting Qt> Qh, the balance between the temperature rising characteristics of the fixing roller 71 and the heating roller 172 is improved, and the temperature control of the fixing device during image formation is facilitated.

As described above, according to the third embodiment of the fixing device of the present invention, the surface heating speed St of the fixing roller 71 alone and the surface heating speed Sh of the heating roller 172 alone are substantially the same. Or Sh is set to a value greater than St, so that the heat generated in the heat ray absorbing layer 71c during the warm-up time is transmitted and absorbed toward the heat generating roller 172, so that the temperature rise rate of the nip portion is increased. Sn
Is reduced, and the warm-up time can be effectively reduced.

The metal base 172a of the heat generating roller 172
By using a metal material having a small heat capacity Ch and a high hardness, the surface heating speed Sh of the heating roller 172 alone is reduced.
Can be set large, the temperature distribution in the longitudinal direction of the shaft can be made uniform, the occurrence of fixing unevenness can be prevented, and the separability of the transfer material P after fixing can be improved.

Further, since the heat value Qt per unit time of the first halogen heater 173 is set to be larger than the heat value Qh per unit time of the second halogen heater 273, the fixing roller 71 and the heat roller 172 are generated. The balance between the respective temperature rising characteristics is improved, and the efficiency of temperature control of the fixing device can be improved.

The above-described first to third embodiments of the present invention show individual best modes to which the present invention is applied, and the described configurations and numerical values limit the scope of the present invention. Not something. Further, by variously combining the above-described first to third embodiments, other embodiments can be easily conceived, but all of them are included in the scope of the present invention.

Further, in the above-described embodiment, an example is shown in which a fixing device according to the present invention is mounted on a color printer as an image forming apparatus. However, a monochrome copying machine, a monochrome printer, a facsimile, and other fixing devices for toner images are used. Needless to say, the present invention can be applied to all the image forming apparatuses requiring the same as in the above-described embodiment.

[0073]

As described in detail above, according to the first to fourth aspects of the present invention, the length of the heat ray generating portion is determined by the distance between the inner ends of the holding members provided at both ends of the fixing roller. By providing a heat insulating member that is set to be short and reduces heat conduction in which the heat generated in the heat ray absorbing layer is transmitted to the holding member, the evaporation and solidification of the lubricating oil accompanying the rise in the temperature of the holding member is effective. This makes it possible to provide a fixing device capable of improving the operation rate and reducing the service cost.

According to the fifth aspect of the present invention, the installation width of the heat ray absorbing layer in the longitudinal direction of the fixing roller is set to substantially match the maximum width of the transfer material to be fixed, and the vicinity of the holding member is set. By preventing the generation of high heat, it is possible to prevent the evaporation and solidification of the lubricating oil due to the rise in the temperature of the holding member, and to provide a fixing device capable of improving the operation rate and reducing the service cost. It works.

According to the sixth and seventh aspects of the present invention, a heat ray blocking member is provided at both ends of the heating element to block the heat ray radiated directly to the holding member, and the heat ray is directed toward the inside of the fixing roller. By reflecting, it is possible to prevent evaporation and solidification of the lubricating oil due to the temperature rise of the holding member, and it is possible to absorb most of the heat rays generated in the heat ray generating portion by the heat ray absorbing layer. In addition, it is possible to provide a fixing device capable of improving the operation rate and reducing the service cost, and improving the efficiency of using heat rays.

According to the present invention, the surface heating speed St of the fixing roller alone and the surface heating speed Sh of the heating roller alone are set to be substantially the same, or Sh is set to S.
By setting the value to be larger than t, it is possible to prevent a decrease in the rate of temperature rise of the nip portion due to transmission and absorption of heat generated in the heat ray absorbing layer during the warm-up time toward the heat generating roller, This has the effect of providing a fixing device that can effectively reduce the warm-up time.

According to the ninth aspect of the present invention, the heat generating roller uses a metal base, and the heat capacity C of the fixing roller alone.
By setting the heat capacity Ch of the heat generating roller to be smaller than t, the surface heating speed Sh of the heat generating roller alone is set to S.
t can be set larger than t, and
The temperature distribution in the longitudinal direction of the shaft is made uniform, and it is possible to prevent the occurrence of fixing unevenness, and to provide a fixing device capable of improving the separability of the transfer material after fixing.

According to the tenth aspect, the heat generation amount Qt per unit time of the first heating element is set to be larger than the heat generation amount Qh per unit time of the second heating element. By improving the balance between the temperature rising characteristics of the fixing roller and the heat generating roller, it is possible to improve the efficiency of temperature control of the fixing device, and to provide a fixing device capable of improving quick start performance. It works.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of a color printer which is an image forming apparatus equipped with a fixing device of the present invention.

FIG. 2 is a cross-sectional view illustrating an internal configuration of the fixing device of the present invention.

FIG. 3 is an enlarged sectional view of a main part of a fixing device including a fixing roller, a pressure roller, and a halogen heater.

FIG. 4 is a plan sectional view of the fixing device according to the first exemplary embodiment of the present invention.

FIG. 5 is a plan cross-sectional view of a fixing device according to a second embodiment of the present invention.

FIG. 6 is a plan sectional view of a fixing device according to a third embodiment of the present invention.

FIG. 7 is an enlarged cross-sectional view of a main part of a fixing device including a fixing roller, a heating roller, and a halogen heater according to a third embodiment of the present invention.

FIG. 8 is a graph showing how the surface temperature of the fixing roller alone, the surface temperature of the heating roller alone, and the temperature of the nip increase with time in the third embodiment of the present invention.

FIG. 9 is a plan sectional view showing the arrangement of a fixing roller, a pressure roller, and a halogen heater in a conventional quick start type fixing device.

[Explanation of symbols]

 7 Fixing Device 70 Fixing Device Main Body Side Plate 70g Heat Ray Blocking Member 71 Fixing Roller 71a Translucent Substrate 71b Translucent Elastic Layer 71c Heat Ray Absorbing Layer 71d Bearing 71f Heat Insulating Sleeve 72 Pressure Roller 73 Halogen Heater (Heat Source) 78 Gear

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2H033 AA02 AA20 AA24 AA30 AA32 BA03 BA05 BA25 BB01 BB04 BB12 BB19 BB21 BB22 BB30 BB33 BB34 BB36 CA27 CA28 CA30 CA45 3J103 AA02 AA15 AA24 GA05 GA30 GA16 GA30 3K058 AA02 AA22 AA34 AA45 AA86 BA18 CA61 CE12 CE16 CE21 DA02

Claims (10)

[Claims] A fixing roller provided with a heat ray absorbing layer for absorbing the heat rays outside a cylindrical light-transmitting base having a light-transmitting property with respect to heat rays; and a holding member for holding both ends of the fixing roller. A fixing device for fixing a toner image on a transfer material to the transfer material, the fixing device including: a heating element configured to fix the toner image on the transfer material to the transfer material; A fixing device for an image forming apparatus, wherein a length of the generating portion is shorter than a distance between inner ends of the holding member. 2. The fixing device according to claim 1, wherein the heating element is a halogen lamp. 3. The fixing device according to claim 1, wherein the holding member is a bearing. 4. The fixing device for an image forming apparatus according to claim 1, wherein a heat insulating member is provided between said fixing roller and said holding member. 5. A fixing roller provided with a heat ray absorbing layer for absorbing the heat rays outside a cylindrical light transmitting base having a light transmissive property with respect to the heat rays, and a holding member for holding both ends of the fixing roller. A fixing device for fixing a toner image on a transfer material to the transfer material, the heating width being provided in a longitudinal direction of the fixing roller. Wherein the maximum width of the transfer material to be fixed is substantially equal to the maximum width of the transfer material. 6. The image according to claim 5, wherein a heat ray blocking member for blocking the heat rays is provided inside the translucent substrate on an end side of the installation width of the heat ray absorbing layer. The fixing device of the forming device. 7. The fixing device according to claim 6, wherein the heat ray blocking member reflects the heat ray. 8. A heat ray absorbing layer that absorbs the first heat ray outside a cylindrical light transmissive body having a light transmissive property with respect to the first heat ray; A fixing roller provided with a first heat generating member for generating a heat ray, and a heat generating roller provided with a second heat generating member for generating a second heat ray inside a cylindrical metal base; In a fixing device in which a toner image on a transfer material is fixed to the transfer material at a nip formed by contacting a roller and the heat generation roller, a surface heating rate St of the fixing roller alone and a surface temperature increase of the heating roller alone The fixing speed of the image forming apparatus is set to be substantially the same as the speed Sh, or the surface heating speed Sh of the heating roller alone is set to a value greater than the surface heating speed St of the fixing roller alone. apparatus. 9. The fixing device of the image forming apparatus according to claim 8, wherein the heat capacity Ct of the fixing roller alone is larger than the heat capacity Ch of the heating roller alone. 10. The heating value Qt of the first heating element per unit time is larger than the heating value Qh of the second heating element per unit time. Fixing device of the image forming apparatus.