JPH1124464A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device which is short in rise time for a heat roller by conducting the heat of a heating element to the heat roller via a heat conductive member. SOLUTION: The device is equipped with the heat roller 2 for fixing which is made of metal, and a backup roller 4 for pressing which firmly contacts it and forms the area of contact between them. The heat roller 2 incorporates the heating element 11, and a heat-conductive layer 12 for conducting the heat of the heating element 11 to the heat roller 2 is formed between the heating element 11 and heat roller 2. This makes it possible to conduct the heat of the elating element 11 to the heat roller 2 via the heat-conductive layer 12, and, therefore, to heat the heat roller 2 efficiently. Further, because a particular part of the heat roller 2 can be heated in the position opposite the area of the contact between the heat roller 2 and backup roller 4 and on this side of the area, heat energy required for fixing can successively be supplied efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for fixing a powder toner in various electrostatic recording devices used for a printer, a facsimile, a copying machine, and the like.

[0002]

2. Description of the Related Art A conventional general fixing device will be described with reference to FIG. FIG. 8 shows a configuration diagram of an example of a conventional fixing device. In the fixing device of FIG.
4, a backup roller 56 whose surface is formed of silicone rubber or the like is pressed against, and a recording paper 58 holding unfixed powder toner is inserted during this time.

A heat roller 54 includes a heating lamp 5.
2 are built-in. The heat roller 54 is rotatably held by a frame 60 via a bearing 62.
Further, a drive gear 64 is fixed to the heat roller 54. The drive gear 64 allows the heat roller 54
Is driven to rotate by external power.

[0004] When the heat roller 54 rotates, the backup roller 56 pressed against the heat roller 54 also rotates in conjunction therewith. By the rotation of the rollers, the recording paper 58 is sequentially fed, and the toner on the recording paper 58 is fixed by receiving heat and pressure.

In recent years, from the viewpoint of energy saving and ease of use, a rise time (hereinafter, referred to as a “warm”) from when the power of the apparatus is turned on until the surface temperature of the heat roller reaches a predetermined temperature to enable fixing. Up Time "
In order to reduce the heat capacity of the heat roller, many attempts have been made to reduce the heat capacity of the heat roller by making the heat roller thinner and smaller in diameter.

[0006]

However, in order to reduce the warm-up time, the above-mentioned conventional fixing device has the following problems.

(1) If the heat roller is made thinner and smaller in diameter to reduce the heat capacity, the bending strength of the heat roller is reduced. For this reason, the heat roller bends at the center, or the nip width near the center decreases, and the fixing becomes non-uniform, so that the conveyance of the recording paper becomes unstable.

(2) A halogen lamp is usually used as a heating lamp, but the heat capacity of the filament, the sealed gas, and the tube wall glass constituting the halogen lamp is large. For this reason, if a halogen lamp is used, there is a certain limit in shortening the warm-up time.

(3) Further, since the transfer of heat from the lamp to the heat roller is by radiation, the heat conductivity is very poor.
The response from ramp up to heat roller ramp up was poor.

(4) Since the heat roller is supported by a bearing outside the width of the recording paper and the drive gear is mounted outside the heat roller, the heat roller has a large unnecessary capacity and inputs a large amount of energy. The warm-up time is longer.

(5) Further, since the heat capacity of the heat roller outside the recording paper width is large, heat flows out to that part and heat radiation from that part is large, and the temperature of the heat roller at both ends of the recording paper decreases. Therefore, it is necessary to take measures such as increasing the amount of heat generated by the lamps at both ends.

(6) Since it is difficult to reduce the diameter of the heat roller, the amount of heat radiated to the outside of the heat roller is large, and the temperature around the heat roller rises. It was difficult to make the image forming apparatus compact because it could not be brought close.

[0013] The fixing device of the present invention solves the above-mentioned problem, and provides a fixing device with a short warm-up time by transferring the heat of a heating element to a heat roller via a heat transfer member. With the goal.

[0014]

In order to achieve the above object, a fixing device according to the present invention comprises an unfixed fixing roller between a fixing heat roller and a pressure backup roller which presses against the fixing heat roller to form a contact area. A fixing element for inserting the recording sheet and fixing the unfixed recording sheet, wherein the heat generating element is formed between the heat generating element and the heat roller. A heat transfer member for transferring heat of the body to the heat roller, wherein the heat generating member can generate heat at a position facing the contact area.

According to the fixing device as described above, the heat energy from the heating element is transferred to the heat roller via the heat transfer member without radiation, so that the time delay for heat transfer and the heat gradient are reduced. The heat roller hardly occurs, and the heat roller can be heated very efficiently. For this reason, the heat roller can be rapidly heated to a predetermined temperature, and the rise time of the heat roller can be significantly reduced. Further, since the heat roller can be locally heated at a position facing the contact region between the heat roller and the backup roller and before the contact region, heat energy required for fixing can be sequentially and efficiently provided, and the heat roller The release of heat energy to the outside air is small, and the energy consumption can be reduced.

In the above-mentioned fixing device, in the frame,
The heat roller and the backup roller are provided, and a bearing roller is provided to be in pressure contact with the heat roller. Both ends of the backup roller are attached to side surfaces of the frame via bearings, and the heat roller is a bearing roller. And the backup roller. According to the above-described fixing device, the length of the heat roller can be made shorter than the length of the backup roller, so that the useless heat capacity of the heat roller can be minimized.

Further, in the fixing device, it is preferable that the bearing roller is disposed at a position symmetrical with respect to a center line connecting an axis of the heat roller and an axis of the backup roller. . According to the fixing device as described above, when the bearing roller is pressed against the heat roller support, the heat roller can be correctly positioned right above the backup roller.

In the fixing device, it is preferable that the heating element is formed to be long in the axial direction of the heat roller. According to the fixing device as described above,
Variations in the temperature distribution in the axial direction of the heat roller can be reduced.

In the fixing device, it is preferable that an axial length of the heat roller is shorter than an axial length of the backup roller. According to the fixing device as described above, the waste heat capacity of the heat roller can be minimized.

In the fixing device, it is preferable that the heat transfer member is a resin compound having high heat resistance. According to the fixing device as described above, heat conduction from the heating element to the heat roller can be improved.

In a preferred fixing device in which the heat transfer member is a resin compound having high heat resistance, it is preferable that the resin compound is a silicone compound.

In the fixing device, the heat transfer member preferably has a brush shape made of a high heat-resistant fibrous material. According to the fixing device as described above, heat conduction from the heating element to the heat roller can be improved.

In a preferred fixing device in which the heat transfer member has a brush shape, the fibrous material is preferably at least one metal material selected from stainless steel, copper, nickel and aluminum, or carbon graphite. .

In the fixing device, it is preferable that the heat transfer member is a liquid material having high heat resistance.
According to the fixing device as described above, heat conduction from the heating element to the heat roller can be improved.

In a preferred fixing device in which the heat transfer member is a liquid material, it is preferable that the liquid material is silicone oil or fluorine oil.
Further, it is preferable that a stirring means for stirring the liquid material is provided.

Further, it is preferable that the stirring means is a projection formed on an inner peripheral portion of the heat roller. If the stirring means is provided as described above, the heat conduction from the heating element to the heat roller can be further improved.

In the fixing device, it is preferable that the heating element is a heating roller having a resistance layer formed on an inner peripheral surface or an outer peripheral surface of the roller via an insulating layer.
According to the fixing device as described above, heat conduction from the heating element to the heat roller can be improved. Further, in the fixing device in which the heating element is preferably a heating roller, it is preferable that the resistance layer forms a heating pattern having a different heating intensity in a circumferential direction of the heating roller. According to the above-described fixing device, the contact area between the heat roller and the backup roller can be heated intensively, so that the fixing performance can be further improved.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a configuration diagram of a fixing device according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view taken along line II of FIG. FIG. 3 is a perspective view of the bearing roller according to the present embodiment.

The heat roller 2 is a cylindrical roller in which a release layer made of a fluororesin or the like is formed on the outer peripheral surface of a cylindrical pipe made of iron. The outer diameter of the base tube is 20 mm and the thickness is 0.1 mm.
35 mm.

The backup roller 4 has a heat-resistant silicone rubber layer 4a formed on the outer periphery of a cored bar 4b. The backup roller 4 is rotatably supported by a frame 6 via a bearing 8. A drive gear 10 is attached to the right end of the cored bar 4b.

The heating element 11 includes a heating element 11a made of ceramics or the like and a heating element holder 11b. The heating element 11 is formed in an elongated shape in the axial direction of the heat roller 2. A compound-like heat conductive layer 12 such as silicone is formed between the heating element 11 and the heat roller 2.

FIG. 3 is a perspective view of the bearing roller 14. The bearing roller 14 is supported by the heat roller support 13 by fitting the roller support shaft 16 into a mounting groove of the heat roller support 13. Bearing roller 14
Can rotate around the roller support shaft 16. The heat roller support 13 includes a guide pin 20 fixed to the frame 6.
And can slide up and down freely. Also,
The bearing roller 14 is pressed against the heat roller 2 by a spring 18.

The roller support shaft 16 is disposed at a position symmetrical with respect to a center line connecting the axis of the heat roller 2 and the axis of the backup roller 4. Thus, when the bearing roller 14 is pressed against the heat roller 2 by the heat roller support 13, the heat roller 2 can be correctly positioned directly above the backup roller 4. That is, the rotational positioning of the heat roller 2 around the backup roller 4 is performed by three points of the backup roller 4 and the two bearing rollers 14. Also,
The positioning of the heat roller 2 in the thrust direction is performed by using the end surface of the heat roller 2 as a guide and the heat roller support 13.
Is made by the end 13a.

Hereinafter, the operation of the fixing device according to the first embodiment will be described. When the apparatus is turned on, first, the heating element 11 generates heat by energization. The heat of the heating element 11 is transferred to the heat roller 2 by heat conduction through the heat conductive layer 12. Since the heat transfer does not depend on radiation, the heat roller 2 can be heated very efficiently, with a time delay of the heat transfer and a very small heat gradient.

When the heat roller 2 reaches a predetermined temperature,
The backup roller 4 starts rotating. The rotation of the backup roller 4 is performed via a drive gear 10 by external power. Since the heat roller 2 is in pressure contact with the backup roller 4, when the backup roller 4 rotates, the heat roller 2 simultaneously starts rotating in conjunction with the rotation.

When the recording paper 22 having an unfixed toner image is inserted between the two rollers while both rollers are rotating, the recording paper 22 receives heat and pressure from the heat roller 2 and the toner image is transferred to the recording paper. 22.

As described above, in the first embodiment, instead of heating the heat roller 2 by the radiation of the lamp heat as in the conventional example, the heat energy from the heating element 11 is heated via the heat conductive layer 12. Therefore, the heat roller 2 can be heated very efficiently. Further, since the position (nip portion) facing the backup roller 4 can be locally heated, the warm-up time can be reduced, and the fixing performance of the recording paper 22 can be improved.

In the prior art, the heat roller is driven to rotate by external power, and the backup roller is rotated in conjunction with the heat. However, the apparatus of the first embodiment rotates the backup roller 4 by external power. ,
The heat roller 2 is rotated in conjunction with this.

For this reason, in the apparatus of the first embodiment, the heat roller 2 is supported by the frame 6 as in the conventional example,
There is no need to extend the outer side of the frame 6 to attach the drive gear 10, and the length of the heat roller 2 can be shorter than the length of the backup roller 4 (the width of the outermost maximum diameter portion). That is, since the heat roller 2 can be shortened to a length substantially equal to the maximum paper width, the heat capacity of the heat roller 2 can be minimized. Thus, by suppressing the heat capacity of the heat roller 2,
The problem that the temperature outside the center of the heat roller 2 tends to decrease can be solved, and the warm-up time can be reduced.

The heat roller 2 of the first embodiment is
The rolling member of the pair of bearing rollers 14 arranged at the top is used as a bearing. Since the contact area between the bearing roller 14 and the heat roller 2 is small, the heat roller 2 has small frictional resistance and is easy to rotate. Further, since the bearing roller 14 has a small volume, heat is hardly discharged from the heat roller 2 and energy loss is small.

When the bearing roller 14 is arranged inside the paper width, the bearing span of the heat roller 2 is shortened, and the heat roller 2 has a small bending even when a small-diameter thin-wall heat roller 2 is used. Becomes stable.

In order to reduce the bending of the heat roller 2, it is effective to add a pair of bearing rollers 14 at the center in addition to the position shown in FIG. By adding a bearing roller in this way, even if the outer diameter of the heat roller 2 is 10 mm or less, the running of the recording paper can be kept sufficiently stable, so that a fixing device that is small, has a small heat capacity, and has a fast start-up is provided. can get.

If the bending rigidity of the heat roller support 13 is increased, the heat roller 2 at the central portion hardly bends, and the heat roller 2 is sufficiently pressed against the central portion, so that the small-diameter heat roller 2 is pressed. It is possible to support without bending. Further, since the heat roller support 13 can be made into a unit of a large number of bearing rollers 14, it is easy to disassemble and assemble.

When the outer periphery of the bearing roller 14 is made of a heat-resistant elastic member such as silicone rubber, the bearing roller 14 comes into contact with the heat roller 2 flexibly, so that the surface of the heat roller 2 can be prevented from being damaged.

The heat roller 2 is rotationally positioned around the backup roller 4 by the backup roller 4 and a pair of bearing rollers 14, and the thrust direction is determined by the heat roller support 13. It is easy to mount and remove, and a small frictional load during rotation ensures stable rotation.

As described above, according to the present embodiment, the warm-up time can be shortened.
Heat roller temperature from 20 ° C to 150 ° C at 50W input
The time required to start up was about 10 seconds.

Needless to say, if the outer diameter of the heat roller 2 is made smaller and thinner than that of the present embodiment, the rise time can be further shortened. If it is less than 0.5 mm, good results can be obtained.

The material of the heat roller 2 is not limited to iron, but may be a material having high thermal conductivity such as aluminum or nickel. In addition, if a self-temperature control type ceramic heating element or the like is used as the heating element 11, it is not necessary to use a special temperature control circuit for the heating element 11 and the heat roller 2. When a heating element other than these is used, a sensor for detecting the temperature of the heat roller 2 or the heating element 11 and a control circuit for controlling a heating signal of the heating element 11 in accordance with a signal from the sensor are used to ensure stable operation. Fixing performance can be obtained.

When the heat conductive layer 12 is made of a compound silicone compound having relatively good heat conductivity, the heat conduction between the heating element 11 and the heat roller 2 can be improved even when the heat roller 2 rotates.

The fixing device of the present invention can be applied not only to an electrostatic recording device but also to a recording paper heating device of another recording system. (Embodiment 2) FIG. 4 is a sectional view of a fixing device according to Embodiment 2 of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted.
The second embodiment differs from the first embodiment in that a brush 32 is provided on the heating element 30.

The heating element 30 includes a heating element 30a and a heating element holder 30b, and is formed to be long in the axial direction of the heat roller 2. The heating element 30a is formed of ceramics or the like as in the first embodiment.

[0052] Between the heating element 30 and the heat roller 2,
A fibrous brush 32 having good heat conductivity is provided. The brush 32 is for efficiently transferring the heat energy generated by the heating element 30 to the heat roller 2.

The brush 32 is obtained by bundling a metallic material in a fiber shape, and the metallic material used is preferably stainless steel, copper, nickel or aluminum. Also, carbon graphite may be bundled in a fibrous form. If the brushes 32 are arranged uniformly in the longitudinal direction of the heat roller 2, variations in the temperature distribution of the heat roller 2 in the axial direction can be reduced.

Also, instead of the brush 32, the brush 32
A sheet-like heat transfer member extending in the longitudinal direction of the heat roller 2 made of the same material as described above may be used. However, when a sheet-shaped heat transfer member is used, it is necessary to secure a stable contact state with the heat roller 2. (Embodiment 3) FIG. 5 is a sectional view of a fixing device according to Embodiment 3 of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted.
The third embodiment is different from the first embodiment in that the heating element 40 is used in the oil bath 42. The heating element 40 is formed by wrapping a heating element around a heating element, and is formed to be long in the axial direction of the heat roller 2. Heating element 40
Is formed of ceramics, nichrome, or the like.

An oil bath 42 having high heat resistance is provided between the heating element 40 and the heat roller 2. The oil bath 42 is for efficiently transferring the heat energy generated by the heating element 40 to the heat roller 2. The oil in the oil bath 42 is preferably silicone oil or fluorine oil.

In the oil bath 42, both ends of the heat roller 2 are sealed with packing members (not shown) in order to prevent oil from leaking from the heat roller 2. Further, instead of using the packing member, drawing may be performed on both ends of the heat roller 2.

As described above, heat transfer through an oily liquid is more efficient than heat transfer through an air layer. In addition, since the contact state between the oil bath 42 and the heating element 40 and the heat roller 2 can be maintained in a favorable state in terms of heat conduction, the heat roller 2 passing through the oil bath 42 from the heating element 40
Since the heat transfer to the heat roller 2 can be efficiently performed, the heating efficiency of the heat roller 2 is very high.

In the third embodiment, the oil bath 42 is agitated as the heat roller 2 rotates,
There is also an effect that the temperature distribution in the inside is made uniform. Further, if protrusions (not shown) such as fins are provided on the inner surface of the heat roller 2, the stirring of the oil bath 42 is further promoted, and the oil bath 4 is stirred.
The temperature distribution in 2 is made more uniform. The uniform temperature of the oil bath 42 has the effect of promoting the heating of the heat roller 2 and increasing the heat transfer effect of the heat roller 2, and greatly contributes to shortening the warm-up time and improving the fixing performance. (Embodiment 4) FIG. 6 is a sectional view of a fixing device according to Embodiment 4 of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted.
The fourth embodiment differs from the first embodiment in that a heating roller 31 is used as a heating element. FIG. 7 is a cross-sectional view of one end of the heat roller 31 according to the fourth embodiment. In FIG. 6, the heating roller 31 is drawn in a single-layer state for convenience, but actually has a three-layer structure as shown in FIG.

The heating roller 31 is made of an aluminum tube 3.
7, a resistance heating layer 34 with an insulating layer 33 interposed therebetween.
Are formed. The aluminum tube 32 has an outer diameter of 1
9 mm and 0.8 mm thick. The electrode pins 36 are pulled out from the resistance heating layer 34 and are fixed to the insulating flange 38.

When the power of the apparatus is turned on, first, the resistance heating layer 34 generates heat by energization, and the aluminum tube 37 generates heat via the insulating layer 33. Therefore, the entire heat generating roller 31 generates heat. The heat of the heat generating roller 31 is transferred to the heat roller 2 via the heat conductive layer 12 by heat conduction. For this reason, the time delay of the heat transfer and the heat gradient are very small, and the heat roller 2 can be heated very efficiently.

As described above, when the heat roller 2 is heated over the entire inner surface, the heat roller 2 in the nip portion can be preheated before the nip portion. It is also possible to form a heating pattern on the resistance heating layer 34 in the circumferential direction. For example, if a heat generation pattern that further increases heat generation in the nip portion and in front of the nip portion, the heat roller 2 can be sufficiently preheated in front of the nip portion, so that the fixing performance of the recording paper 22 can be more efficiently improved. it can.

Further, instead of the heat conductive layer 12, heat may be transferred by a brush or an oil bath. For example, if the brush is arranged so that heat is intensively transferred in the vicinity of the nip portion and the oil height of the oil bath is set, concentrated heating can be performed in the nip portion as in the case of forming the heat generation pattern.

In the fourth embodiment, the resistance heating layer 34 is formed on the inner surface of the raw tube 32, but may be formed on the outer surface of the raw tube 37. Further, although aluminum is used for the raw tube 37, if an insulating material such as heat-resistant glass or ceramics is used, it is not necessary to form the insulating layer 33 specially.

[0064]

As described above, according to the fixing device of the present invention, the heat energy from the heating element is transferred to the heat roller via the heat transfer member without being radiated. Delays and heat gradients are less likely to occur, and the heat roller can be heated very efficiently. For this reason, the heat roller can be rapidly heated to a predetermined temperature, and the warm-up time can be significantly reduced.

Further, since the heat roller can be locally heated at the position opposite to and in front of the contact area between the heat roller and the backup roller, the heat energy required for fixing can be provided sequentially and efficiently. The release of heat energy from the heat roller to the outside air is small, and the energy consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a fixing device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line II of FIG.

FIG. 3 is a perspective view of a bearing roller used in the fixing device of the present invention.

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

FIG. 5 is a sectional view of a fixing device according to a third embodiment of the present invention.

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

FIG. 7 is a cross-sectional view of one end of a heat roller according to a fourth embodiment of the present invention.

FIG. 8 is a configuration diagram of an example of a conventional fixing device.

[Explanation of symbols]

 Reference Signs List 2 heat roller 4 backup roller 4a silicone rubber layer 4b cored bar 6 frame 8 bearing 10 drive gear 11, 30, 40 heating element 11a, 30a heating element 11b, 30b heating element holder 12 heat conductive layer 13 heat roller support 13a end Part 14 Bearing roller 16 Roller support shaft 18 Spring 20 Guide pin 22 Recording paper 31 Heating roller 32 Brush 33 Insulating layer 34 Resistance heating layer 36 Electrode pin 37 Element tube 38 Insulating flange 42 Oil bath

Claims (15)

[Claims] 1. A fixing device for fixing an unfixed recording sheet by inserting an unfixed recording sheet between a fixing heat roller and a pressure backup roller which presses against the fixing heat roller to form a contact area. A heating element included in the heat roller, and a heat transfer member formed between the heating element and the heat roller, for transferring heat of the heating element to the heat roller, A fixing device, wherein a heating element can generate heat at a position facing the contact area. 2. A heat roller and the backup roller are disposed in a frame, and a bearing roller is provided for pressing the heat roller against the heat roller. Both ends of the backup roller are mounted on side surfaces of the frame via bearings. And
The fixing device according to claim 1, wherein the heat roller is sandwiched between the bearing roller and the backup roller. 3. The fixing device according to claim 2, wherein the bearing roller is disposed at a position symmetrical with respect to a center line connecting an axis of the heat roller and an axis of the backup roller. 4. The fixing device according to claim 1, wherein the heating element is formed to be long in the axial direction of the heat roller. 5. An axial length of the heat roller is shorter than an axial length of the backup roller.
5. The fixing device according to any one of items 1 to 4. 6. The fixing device according to claim 1, wherein the heat transfer member is a resin compound having high heat resistance. 7. The fixing device according to claim 6, wherein the resin compound is a silicone compound. 8. The fixing device according to claim 1, wherein the heat transfer member has a brush shape formed of a fibrous material having high heat resistance. 9. The fibrous material is made of stainless steel, copper,
9. The fixing device according to claim 8, wherein the fixing device is at least one metal material selected from nickel and aluminum or carbon graphite. 10. The fixing device according to claim 1, wherein the heat transfer member is a liquid material having high heat resistance. 11. The fixing device according to claim 10, wherein the liquid material is silicone oil or fluorine oil. 12. The fixing device according to claim 10, further comprising stirring means for stirring the liquid material. 13. The fixing device according to claim 12, wherein the stirring means is a projection formed on an inner peripheral portion of the heat roller. 14. The fixing device according to claim 1, wherein the heating element is a heating roller having a resistance layer formed on an inner peripheral surface or an outer peripheral surface of the roller via an insulating layer. 15. The fixing device according to claim 14, wherein the resistance layer forms a heat generation pattern having different heat generation strengths in a circumferential direction of the heat generation roller.