JP3453232B2 - Heat fixing roller and fixing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in an image forming apparatus such as a copying machine, a facsimile apparatus, and a printer to fix a toner image transferred on a recording sheet. The present invention relates to a direct heating type heat fixing roller and a fixing device. 2. Description of the Related Art Generally, in this type of image forming apparatus, it is necessary to heat-fix a toner image transferred on a recording sheet to the recording sheet by entanglement of the toner particles with fibers of the recording sheet. . For this reason, the fixing roller of the fixing device is often configured as a heat roller. [0003] As such a heat roller (heat fixing roller), an indirect heating type in which a heat source such as an infrared lamp or a halogen lamp is provided at an axial position of a metal sleeve having good heat conductivity is generally used. However, in the case of the indirect heating type heat fixing roller, an expensive thin tubular lamp is required, and
The temperature cannot be raised quickly because of indirect heating.
There are problems such as. [0004] For these reasons, in recent years, a direct heating type heat fixing roller has begun to spread in place of the indirect heating type. One example is disclosed in, for example, JP-A-5-14296.
No. 0 discloses this. FIG. 10 shows the outline,
The sheet-shaped heating resistor 51 formed in a flat shape is rolled into a roll shape and inserted into a cylindrical roller main body 52, whereby the sheet-shaped heating resistor 51 attempts to spread outward. To contact the inner peripheral surface 53 of the roller body 52,
The roller body 52 is directly heated by energizing such a sheet-like heating resistor 51. However, the sheet-shaped heating resistor 51 does not always adhere to the inner peripheral surface 53 of the roller body 52, and for example, as shown in FIG. Floats 54 from surface 53 may occur. In the portion where such a floating 54 occurs, heat transfer from the sheet-shaped heating resistor 51 to the roller main body 52 is poor, and the temperature of the roller main body 52 becomes uneven. As a result, the fixing property is deteriorated, and a toner image portion that causes poor fixing is generated, and such toner may adhere to a user's hand or clothes and become dirty, which is not preferable. Accordingly, the present invention provides a method of heating a roller body directly by rolling a sheet-like heating resistor having elasticity into a roll shape, inserting it into a roller body, and using the elasticity to closely contact the inner peripheral surface of the roller body. Heat fixing roller
An object of the present invention is to improve the adhesiveness of a sheet-like heating resistor to the inner peripheral surface of a roller body. According to a first aspect of the present invention, there is provided a heat fixing roller, comprising: a cylindrical roller main body having a release layer formed on an outer peripheral surface; And a sheet-shaped heating resistor which is inserted into the roller body and is brought into close contact with the inner peripheral surface of the roller body in an electrically insulated state, wherein the sheet-shaped heating resistor directly heats the roller body. in the roller, the sheet-like heating resistor, have a structure to weaken the elastic force of the end of the rounding direction of the rolled structure to weaken the elastic force, the rolled
Is an intermittent hole structure formed at the end in the rounding direction of
The intermittent hole structure has a shape that expands as each hole approaches an end. Accordingly, since the elastic force of the end of the sheet-shaped heating resistor is weakened, the end of the sheet-shaped heat generating resistor easily extends along the inner peripheral surface of the roller body, and the end of the sheet-shaped heat generating resistor extends from the inner peripheral surface near the end. Floating hardly occurs. Thereby, the adhesion of the sheet-shaped heating resistor to the inner peripheral surface of the roller body is improved. [0009] Thus, as the structure to weaken the elastic force of the end portion of the sheet-like heating resistor, a simple structure such as intermittent hole structure formed at the end of the B Lumpur shaped rounding direction realizable. [0010] In particular, with respect to the intermittent hole structure formed on an end portion of the B Lumpur shaped rounding direction, that each hole shall have a shape that extends in accordance becomes end, the elastic force of more end As a result, the adhesion to the inner peripheral surface of the roller body is further improved. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of the present invention.
A description will be given based on FIG. This embodiment relates to a heat fixing roller 1 of a direct heating type. The heat fixing roller 1 is configured based on a cylindrical roller body 2. The roller main body 2 is formed, for example, as a metal roller made of aluminum or the like having good thermal conductivity in which the inner peripheral surface 3 is insulated, an insulating roller made of an insulator made of glass or the like, or a resin roller made of a heat-resistant resin. A release layer such as Teflon is formed on the outer peripheral surface 4 to prevent paper wrapping during fixing. Further, a sheet-like heating resistor 5 which is rolled into a roll and inserted into the roller body 2 is provided. This sheet-shaped heating resistor 5 is made of molybdenum,
It is formed in a sheet shape using a metal such as tungsten as a raw material and has elasticity. It has a length equal to the length of the roller body 2 and has both ends 6a and 6b in a roll-shaped rounding direction. Cut structures 7a and 7b are formed to reduce the elastic force of these ends 6a and 6b. These cutting structures 7a, 7b are provided at the ends 6a, 6
It has a shape in which the triangular cuts 8a and 8b that are wider as b becomes continuous. Also, the cutting structures 7a, 7b
The relationship between the cuts 8a and 8b is such that when the sheet-like heating resistor 5 is rolled into a roll,
It is a positional relationship. In a state where the cuts 8a and 8b are engaged with each other, the length of the sheet-shaped heating resistor 5 in the rounding direction is set to be substantially equal to the length of the inner peripheral surface 3 of the roller body 2. In the sheet-shaped heating resistor 5, reference numeral 9 denotes an energizing pattern, and 10 denotes an electrode pattern which receives a sliding contact with an energizing brush (not shown) or the like, and is formed at both ends in the roller axial direction. In such a configuration, the heat-fixing roller 1 is manufactured by rolling the sheet-shaped heating resistor 5 into a roller shape in the roller body 2 and inserting it in the axial direction. Since the sheet-like heat generating resistor 5 inserted into the roller body 2 has elasticity, the sheet-like heat generating resistor 5 exhibits a property of expanding outward along the inner peripheral surface 3 due to the elasticity. In close contact. In this adhesion process, both ends 6 in the rounding direction
Since a and 6b have cut structures 7a and 7b and the elastic force of the portions is weakened, the end portions 6a and 6b are not stretched against the inner peripheral surface 3 and are easily extended along the inner peripheral surface 3. Become. As a result, the sheet-like heating resistor 5 is prevented from floating near the end portions 6a and 6b, and comes into close contact with the inner peripheral surface 3. In particular, in the cut structures 7a and 7b,
Since the cuts 8a and 8b are formed so as to be wider toward the ends, and the elastic force is weakened toward the ends, the floating prevention effect near the ends 6a and 6b is enhanced. When the sheet-like heating resistor 5 has the cut structures 7a and 7b, heat is not generated in the cuts 8a and 8b, and therefore, there is a possibility that temperature unevenness may occur in the joining region of the both ends 6a and 6b in the rounding direction. . In this regard, in the present embodiment, the cuts 8a and 8b are shaped so as to mesh with each other, so that the portions that do not generate heat complement each other,
The heat generation state in the joining regions at both ends 6a and 6b in the rounding direction is also good, and there is no temperature unevenness. In this embodiment, the notch structure 7 is used.
Although a and 7b are formed by triangular cuts 8a and 8b, they are not limited to such shapes, but may be of any shape. For example, a rectangular cut 11 as shown in FIG.
The cutting structures 7a and 7b may be formed by a and 11b.
The cuts 11a and 11b are also set so as to mesh with each other. In addition, for example, a cut structure in which semicircular cuts are continuous may be used. Also in the case of this semicircular cut, a structure in which the elastic force becomes weaker toward the end can be obtained. A second embodiment of the present invention will be described with reference to FIG. 1 and 2 are denoted by the same reference numerals, and description thereof is omitted (the same applies to the following embodiments described later). In the present embodiment, with respect to the sheet-like heating resistor 5 which is rolled into the roller body 2 and inserted into the roller body 2, both ends 6a and 6b in the roll direction of the roll (in FIG. As a structure for weakening the elastic force on the 6a side only, the thin structures 12a and 12b (the thin structures 12a in the drawing are reduced in thickness toward the ends 6a and 6b).
Only is shown). When the sheet-shaped heating resistor 5 having such thin structures 12a, 12b at the end portions 6a, 6b is used, when the heating resistor 5 is inserted into the roller main body 2, its own elasticity causes the inner peripheral surface 3 to be formed. It shows the property of spreading outward along with it, and comes into close contact with the inner peripheral surface 3 of the roller body 2. In this close contact process, both ends 6a and 6b in the rounding direction are thin
Since the end portions 6a and 6b have the a and 12b and the elastic force of the portions is weakened, the end portions 6a and 6b are not stretched against the inner peripheral surface 3 and are easily extended along the inner peripheral surface 3. As a result, the floating of the sheet-shaped heating resistor 5 near the ends 6a and 6b is prevented, and the sheet-shaped heating resistor 5 comes into close contact with the inner peripheral surface 3. The thin structures 12a and 12b include:
The present invention is not limited to the stepwise one as shown in FIG. 4A, and may be a continuous one having a tapered tapered shape as shown in FIG. 4B, for example. Thin structure 1 that becomes thin continuously
According to 2a and 12b, the elastic force in the vicinity of the ends 6a and 6b also gradually decreases toward the ends, and the floating of the sheet-like heating resistor 5 in the vicinity of the ends 6a and 6b can be more effectively prevented. Can be prevented. A third embodiment of the present invention will be described with reference to FIG. In the present embodiment, the curl structure 13a is used as a structure for weakening the elastic force at both ends 6a and 6b of the sheet-shaped heating resistor 5 which is rolled and inserted into the roller body 2 in the rolled direction. , 13b. Here, the curvatures of the curl structures 13 a and 13 b are set to be larger than the inner peripheral surface 3 of the roller body 2. When the sheet-like heat generating resistor 5 having the curl structures 13a, 13b at the ends 6a, 6b is used, when the heat generating resistor 5 is inserted into the roller body 2, its own elasticity causes the inner peripheral surface 3 to be formed. It shows the property of spreading outward along with it, and comes into close contact with the inner peripheral surface 3 of the roller body 2. In this close contact process, both ends 6a and 6b in the rounding direction have curl structures 13a and 13b that are away from the inner peripheral surface 3, and the elastic force (the pressing force against the inner peripheral surface 3) at those portions is weakened. As a result, the end portions 6a and 6b are not stretched against the inner peripheral surface 3 and are easily extended along the inner peripheral surface 3.
As a result, the sheet-like heating resistor 5 is prevented from floating near the end portions 6a and 6b, and comes into close contact with the inner peripheral surface 3.
This is because of the curl structure 13a, 1 at the end 6a, 6b.
The smaller the radius of curvature of 3b, the more effective. A fourth embodiment of the present invention will be described with reference to FIG. In the present embodiment, an intermittent hole structure is used for a sheet-like heating resistor 5 that is rolled into the roller body 2 and inserted into the roller body 2 as a structure for weakening the elastic force at both ends 6a and 6b in the rolling direction. 14a and 14b. These intermittent hole structures 14a, 14b are provided with end portions 6a,
The triangular holes 15 expanding toward the 6b side are intermittently arranged in the roller axis direction. When the sheet-like heat generating resistor 5 having the intermittent hole structures 14a and 14b at the ends 6a and 6b is used, when the heat generating resistor 5 is inserted into the roller body 2, the inner peripheral surface 3 is elastically formed by itself. And tends to spread outward along the inner surface of the roller body 2. In this close contacting process, discontinuous hole structures 14a and 14b are provided near both ends 6a and 6b in the rounding direction, and the elastic force near the ends 6a and 6b is weakened. 6
The tension of a and 6b is eliminated, and it is easy to extend along the inner peripheral surface 3. As a result, the sheet-like heating resistor 5 is prevented from floating near the end portions 6a and 6b, and comes into close contact with the inner peripheral surface 3. This is more effective as the intermittent hole structures 14a, 14b at the ends 6a, 6b are closer to the edges of the ends 6a, 6b. In this embodiment, the intermittent hole structure 14 is used.
Although a and 14b are formed by the triangular holes 15, the shape is not limited to such a shape, and any shape may be adopted. For example, intermittent hole structures 14a and 14b with rectangular holes 16 as shown in FIG. 7 may be used. In each of the above-described embodiments, both ends 6a, 6a of the sheet-shaped heating resistor 5 in the roll-shaped rounding direction are used.
Although b has the structures 7, 12, 13, and 14 for weakening the elastic force, these structures 7, 12, 13, and 14 may be provided only on one end 6a or 6b.
In these cases, the sheet-shaped heating resistor 5 has the structures 7, 12,
The end 6a or 6b having the side 13 or 14 has an inner side, and the ends 6a and 6b have a length overlapping each other (that is, a length longer than the inner peripheral surface 3). Good to do. When only one end 6a or 6b is provided with the structure 7, 12, 13, 14 for weakening the elastic force, it is not as effective as when the structure is provided at both ends 6a, 6b. It can be more effectively brought into close contact with the inner peripheral surface 3 than when only the body 5 is used. A fifth embodiment of the present invention will be described with reference to FIG. In the present embodiment, the sheet-shaped heating resistor 17 which is rolled into the roller body 2 and inserted into the roller body 2 is the conventional sheet-shaped heating resistor 5 shown in FIG.
A simple sheet-like elastic material similar to 1 is used. A coil spring 18 is tightly fitted in the sheet-like heating resistor 17 inserted in the roller body 2. The coil spring 18 has a length (here, about the entire length of the sheet-shaped heating resistor 17 in the roller axis direction).
It has a slightly shorter length, is set so that the end of the sheet-shaped heating resistor 17 in the roller axis direction is exposed), and has an inner peripheral surface 3 of the roller body 2 (the inserted sheet-shaped heating resistor 17). One having an outer diameter (winding diameter) larger than the diameter of the inner peripheral surface 19) of the body 17 is used. Also,
The coil spring 18 is formed of an insulating material such as an insulating resin. The coil spring 18 is tightly fitted by being axially inserted into the inner peripheral surface 19 of the sheet-like heating resistor 17 in the roller body 2 while being twisted in a direction to reduce the winding diameter. Therefore, the diameter of the coil spring 18 closely fitted to the inner peripheral surface 19 of the roll-shaped sheet-shaped heat generating resistor 17 in the state of reduced diameter has a property of expanding the diameter almost uniformly so that the twist is released. The heating resistor 17 is forcibly pressed against the inner peripheral surface 3 of the roller main body 2 so as to be in close contact with the entire surface without floating. Here, when the coil spring 18 is made of a conductive material, it is difficult to insulate it from the sheet-shaped heating resistor 17. Leaks and shorts can occur. In this regard, in this embodiment, since the coil spring 18 is made of an insulating material, such a disadvantage, that is, the sheet-like heating resistor 17 is used.
From the end in the roll direction of the coil spring 18
There is no possibility of leakage or short-circuit, and safety can be ensured. In these embodiments, at least the inner peripheral surface 3 of the roller body 2 is made insulative so that the inner peripheral surface 3 and the sheet-like heating resistors 5 and 17 are electrically insulated. Although they are brought into close contact with each other, this is a relative relationship, and the inner peripheral surface 3 is formed by insulatingly covering the surfaces of the sheet-like heating resistors 15 and 17 (the surfaces that become the outer peripheral surfaces in a rolled state).
May be ensured in electrical insulation. A sixth embodiment of the present invention will be described with reference to FIG. This embodiment relates to the fixing device 20. The fixing device 20 includes a pair of a direct heating type heat fixing roller 1 having a configuration as exemplified in each of the above-described embodiments and a pressure roller 21 pressed against and contacted with the heat fixing roller 1. The toner image is fixed on the recording paper 22 by passing the recording paper 22 through the nip portions of the rollers 1 and 21. Here, an energizing means 24 for energizing by applying a voltage between the both ends in the roller axis direction of the sheet-shaped heating resistor 5 (or 17) inserted into the heat fixing roller 1 through an energizing terminal 23 or the like is also provided. Is provided. Various general methods can be adopted as a method of supplying power to the sheet-like heating resistor 5 (or 17), and thus details thereof are omitted. According to the fixing device 20 of the present embodiment, as described above, the heating and fixing roller 1 having the sheet-like heating resistors 5 and 17 inserted with good adhesion to the inner peripheral surface 3 is provided. As a result, the roller body 2, that is, the heating and fixing roller 1 can be directly heated in a state where the temperature unevenness is small, and a stable fixing property can be obtained. Therefore, the fixing operation for the toner image on the recording paper 22 is stably performed. [0039] According to claim 1 Symbol placement of invention, according to the present invention, the sheet-like heating resistor is inserted into rounded to a roll roller body is, the elastic force of the end of the roll-shaped rounding direction Is weakened, so that its end is easy to extend along the inner peripheral surface of the roller body, and it is hard to float from the inner peripheral surface near the end, so the inner peripheral surface of the roller body of the sheet-like heating resistor is Adhesion to the substrate can be improved. In particular, regarding the cut structure formed at the end in the roll direction in the rounding direction , each hole has a shape that expands toward the end, so that the elastic force at the end is further reduced, and the inner circumference of the roller body is further reduced. Adhesion to the surface can be further improved. ## EQU00001 ##

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a sheet-like heating resistor according to a first embodiment of the present invention. FIG. 2 is an external perspective view of a heat fixing roller showing an interposed state of the sheet-shaped heating resistor. FIG. 3 is a plan view of a sheet-like heating resistor showing a modification. FIG. 4 is an enlarged cross-sectional view showing the vicinity of an end of a sheet-shaped heating resistor according to a second embodiment of the present invention. FIG. 5 is a side view of a sheet-shaped heating resistor according to a third embodiment of the present invention. FIG. 6 is a plan view of a sheet-shaped heating resistor according to a fourth embodiment of the present invention. FIG. 7 is a plan view of a sheet-like heating resistor showing a modification. FIG. 8 is a sectional view of a heat fixing roller according to a fifth embodiment of the present invention. FIG. 9 is a schematic perspective view of a fixing device showing a sixth embodiment of the present invention. FIG. 10 is an exploded perspective view showing a conventional example. FIG. 11 is a front view showing a state in which floating occurs. DESCRIPTION OF SYMBOLS 1 Heat fixing roller 2 Roller body 3 Inner peripheral surface 4 Release layer 5 Sheet heating resistors 6a, 6b Ends 7a, 7b Cut structures 8a, 8b Cut 12a Thin structures 13a, 13b Curl structures 14a, 14b Intermittent hole structure 15 Hole 17 Sheet heating resistor 18 Coil spring 19 Inner circumferential surface 21 of sheet heating resistor 21 Pressure roller 24

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 15/20

Claims (1)

(57) [Claim 1] A cylindrical roller body having a release layer formed on the outer peripheral surface thereof, and an elastically rolled roll body which is inserted into the roller body. A sheet-like heating resistor closely adhered to the inner peripheral surface of the roller body in an electrically insulated state,
In the heat fixing roller for heating the roller body directly by the sheet-like heating resistor, the sheet-like heating resistor, have a structure to weaken the elastic force of the end of the roll-shaped rounding direction, weakening the elastic force Construction
Is an intermittent hole formed at the end of the roll in the rounding direction.
This intermittent hole structure is designed so that each hole becomes an end.
Heat fixing roller, characterized in that the perforated gastric spreading shape.