JP6890997B2 - A film used for the fixing device and a fixing device provided with this film - Google Patents

Description

The present invention relates to a film used in a fixing device mounted on an image forming apparatus such as a printer and a copying machine, and a fixing device including the film.

As a film used in a fixing device mounted on a copying machine or a printer, a film having electrode portions formed at both ends in the longitudinal direction of the film and heat generating portions provided between the electrode portions is known. (Patent Document 1). The fixing device using this film generates heat by utilizing Joule heat generated by bringing an electrode member such as a conductive brush into contact with the electrode portion and passing an electric current through the heat generating portion. Since the film itself generates heat, this film can contribute to energy saving of the fixing device and shortening of warm-up time.

Japanese Unexamined Patent Publication No. 2011-253141

However, in the above film, since it is preferable to suppress heat generation of the electrode portion that does not directly contribute to the heating of the image, the electrode portion may be formed of a conductive layer made of a different material having a resistance value lower than that of the heat generating portion. .. There is a problem that the conductive layer may be peeled off from the base layer due to the difference in the coefficient of thermal expansion between the heat generating portion and the conductive portion.

The first preferred embodiment for solving the above problems is a tubular film used for a fixing device, which includes a base layer and an electrode portion formed at an end portion of the base layer in the longitudinal direction of the film. , is formed in a central portion of the base layer with respect to the longitudinal direction of the said film, said has an electrode portion electrically connected to the heat generating portion, said electrode portion, and the heat generating portion, but conductive of the same material is formed in the layer, the direction of the electrode portion is rather thick thickness of the conductive layer than the heating portion, the electrode portion may be a circumferentially extending said conductive layer forming portions of the annular said film The heat generating portion is characterized in that it is a portion formed by arranging a plurality of the thin linear conductive layers extending in the longitudinal direction of the film at intervals with respect to the circumferential direction of the film.

The second preferred embodiment for solving the above problems is a tubular film, which comprises a base layer, an electrode portion formed at an end portion of the base layer in the longitudinal direction of the film, and the film. and relates to a longitudinal direction is formed in a central portion of the base layer the electrode portion and electrically connected to the heat generating portion, and a film having a contact with the conductive cathode layer, supplying power to the heating unit through the electrode portion In a fixing device having a power supply member that generates electricity by the current flowing through the heat generating portion and fixing a toner image to a recording material by the heat of the film, the electrode portion, the heat generating portion, and the like. is formed of a conductive layer of the same material, the direction of the electrode portion is rather thick thickness of the conductive layer than the heating portion, the electrode portion is in the conductive layer of the annular extending in a circumferential direction of the film It is a formed portion, and the heat generating portion is a portion formed by arranging a plurality of the thin linear conductive layers extending in the longitudinal direction of the film at intervals with respect to the circumferential direction of the film. It is something to do.

A third preferred embodiment for solving the above problems is a method for producing a film having a tubular base layer and a conductive pattern formed on the base layer and used for a fixing device. The first step of printing the conductive pattern on the edges and the center of the base layer in the longitudinal direction of the film over the circumferential direction of the film, and the end portion of the conductive pattern formed in the first step. It is characterized by having a second step of printing the conductive pattern over the film in the circumferential direction.

A fourth preferred embodiment for solving the above problems is a method for producing a film having a tubular base layer and a conductive pattern formed on the base layer and used for a fixing device. The first step of printing the conductive pattern over the circumferential direction of the film only on the end portion of the base layer in the longitudinal direction of the film, and the conductive pattern formed on the end portion of the base layer are superimposed on each other. It is characterized by having a second step of printing the conductive pattern in the circumferential direction of the film and at the same time printing the conductive pattern in the central portion in the longitudinal direction of the film over the circumferential direction of the film. It is a thing.

A fifth preferred embodiment for solving the above problems is a tubular film used for a fixing device, which includes a base layer and an electrode portion formed at an end portion of the base layer in the longitudinal direction of the film. , is formed in a central portion of the base layer with respect to the longitudinal direction of the said film, said has an electrode portion electrically connected to the heat generating portion, said electrode portion, and the heat generating portion, but the same material A second conductive layer formed of one conductive layer and having a lower volume resistance than the first conductive layer is formed on the electrode portion, and the second conductive layer is formed in the longitudinal direction of the film. The layer is characterized in that it is formed so as to overlap the boundary between the heat generating portion and the electrode portion.

In the film used in the fixing device, it is possible to suppress the peeling of the conductive layer during thermal expansion while suppressing the heat generation of the electrode portion.

Schematic cross-sectional view of the fixing device used to explain the first embodiment Frontal schematic view of the fixing device in the first embodiment A perspective view and a longitudinal sectional view of the film 36 in the first embodiment. Circumferential sectional view showing the layer structure of the film 36 in the first embodiment. Schematic diagram showing the electrical connection in the first embodiment The figure which showed the print pattern example in 1st Example The figure which showed the calorific value of the film 36 in 1st Example Schematic cross-sectional view of the fixing device used to explain the second embodiment Frontal schematic view of the fixing device in the second embodiment A perspective view and a longitudinal sectional view of the fixing roller 62 in the second embodiment. Circumferential sectional view showing the layer structure of the fixing roller 62 in the second embodiment. Schematic diagram showing the electrical connection in the second embodiment The figure which showed the calorific value of the fixing roller 62 in the 2nd Example Longitudinal sectional view of the film 36 in the third embodiment A perspective view and a longitudinal sectional view of the film 36 in the fourth embodiment. Circumferential sectional view showing the layer structure of the film 36 in the fourth embodiment. A perspective view and a longitudinal sectional view of the film 36 in the fifth embodiment.

Hereinafter, the present invention will be described in detail based on examples.

(First Example)
The first embodiment will be described with reference to FIGS. 1-6, 7 and 15. FIG. 1 is a schematic cross-sectional view of the fixing device 18, and FIG. 2 is a front schematic view of the fixing device 18. In the following description, the longitudinal direction is the X-axis direction in the drawing, the width direction is the Y-axis direction which is the transport direction of the recording material, and the height direction is the Z-axis direction. The fixing device 18 is a resistance heat generation type, and resistance heat generation (Joule heat generation) is generated by passing a current directly through the conductive layer of the film 36. A feature of this type of fixing device is that since the film 36 itself generates heat, the device can be started up with higher thermal efficiency and higher speed than a device that heats the film 36 with a halogen heater or the like.

Reference numeral 31 is a film assembly containing the film 36, and 32 is a pressure roller. The pressure roller 32 and the film assembly 31 are arranged vertically in parallel between the left and right side plates 34. The left and right side plates 34 are fixed to the device frame 33.

FIG. 3 is a perspective view showing the structure of the film 36 and a cross-sectional view in the longitudinal direction. The film 36 has a flexibility by providing a conductive layer 36b on a base layer 36a and further forming an elastic layer 36c and a release layer 36d on the conductive layer 36b. In order to make the structure of the conductive layer 36b easy to understand, the elastic layer 36c and the release layer 36d are partially omitted in the perspective view. FIG. 4A shows a cross-sectional view of the end portion of the film 36 in the longitudinal direction, and FIG. 4B shows a cross-sectional view of the central portion. In order to make the layer structure of the film 36 easy to understand, the width and spacing of the conductive layers 36b and the ratio of the thickness of each layer are different from the actual ones.

In this embodiment, a polyimide base material having a thickness of about 60 μm formed in a tubular shape is used as the base layer 36a. A conductive layer 36b is formed on the base layer 36a in the longitudinal direction. The conductive layer 36b is divided into an electrode portion 361b and a heat generating portion 362b in the longitudinal direction. The reason will be described later, but the thickness of the conductive layer 36b in the electrode portion 361b is 20 μm, and the thickness of the conductive layer in the heat generating portion 362b is 10 μm. The electrode portion 361b is formed in a region having a width of about 10 mm at both ends in the longitudinal direction of the film 36, and is formed of an annular conductive layer 36b extending in the circumferential direction of the film 36. The heat generating portion 362b is formed in the region between the electrode portions 361b formed at both ends of the film 36. The heat generating portion 362b is formed so that a plurality of thin linear conductive layers 36b extending in the longitudinal direction of the film 36 are arranged at intervals in the rotation direction of the film 36. The plurality of thin wire-shaped conductive layers 36b are substantially parallel to each other, have a width of about 0.5 mm, and have an interval of about 1.5 mm between the thin wire-shaped conductive layers 36b. Since the surface area per unit length of the film 36 in the longitudinal direction of the heat generating portion 362b is smaller than that of the electrode portion 361b, the heat generating portion 362b has a higher resistance than the electrode portion 361b and the amount of heat generated becomes larger. The method of forming the conductive layer 36b on the base layer 36a includes means such as printing, plating, sputtering, and vapor deposition, and in this embodiment, the conductive layer 36b is formed by screen printing silver ink.

An elastic layer 36c made of silicone rubber or fluororubber having a thickness of about 200 μm was formed on the conductive layer 36b, and a release layer 36d of a PFA resin tube having a thickness of about 15 μm, which was the outermost layer, was coated on the elastic layer 36c. In this embodiment, the film 36 has an inner diameter of about 18 mm. The elastic layer 36c and the release layer 36d are not provided on the electrode portion 361b, and only the heat generating portion 362b is covered.

The pressure roller 32 has a core metal 32a, an elastic layer 32b formed on the outside of the core metal 32a, and a release layer 32c formed on the outside of the elastic layer 32b. The core metal 32a is made of a metal such as stainless steel. The elastic layer 32b is made of silicone rubber or fluororubber. The release layer 32c is formed of a fluororesin such as PFA, PTFE, or FEP. In this embodiment, an elastic layer 32b of a silicone rubber layer having a thickness of about 3.5 mm is formed on a core metal 32a having an outer diameter of 11 mm of stainless steel by injection molding, and a PFA coat layer having a thickness of about 40 μm is further separated on the elastic layer 32b. A pressure roller 32 on which the mold layer 32c was formed was used. The outer diameter of the pressure roller 32 is about 18 mm. The hardness of the pressure roller 32 is preferably in the range of 40 ° to 70 ° from the viewpoint of securing the fixing nip N and durability under a load of 9.8 N with an ASKER-C hardness tester. In this embodiment, it is set to 54 °. As shown in FIG. 2, the pressure rollers 32 are arranged at both ends of the core metal 32a in the longitudinal direction so as to be rotatably supported between the device frame side plates 34 via bearing members 35, respectively. G is a drive gear fixed to one end of the core metal 32a. A rotational force is transmitted to the drive gear G from a drive mechanism unit (not shown) to rotationally drive the pressure roller 32.

As shown in FIG. 1, the film assembly 31 guides the film 36 and the film 36 from the inside, and the holder 38 as a nip portion forming member that forms a nip portion between the film 36 and the pressure roller 32 via the film 36. Has. The film assembly further includes a stay 40 to reinforce the holder 38 and left and right flanges 41 as regulatory members to regulate the longitudinal movement of the film 36.

As shown in FIG. 1, the holder 38 has a substantially semicircular gutter shape in cross section, is a member having rigidity, heat resistance, and heat insulating properties, and is formed of a liquid crystal polymer or the like. The holder 38 also has a role as a guide member for guiding the rotation of the film 36 outerly fitted to the holder 38.

The stay 40 is a member having a U-shaped cross section and long in the longitudinal direction of the film 36. The stay 40 is inserted inside the holder 38, and the film 36 is put on the outside of the holder 38. The left and right flanges 41 are fitted to the left and right outer extension arms of the stay 40, respectively. In this way, the film assembly 31 is assembled.

As shown in FIG. 1, the film assembly 31 is arranged substantially in parallel on the upper side of the pressure roller 32 with the holder 38 side facing downward, and is arranged between the left and right side plates 34. The left and right flanges 41 are engaged with the vertical groove portions provided on the left and right flanges 41 with the vertical edge portions provided on the left and right side plates 34, respectively. In this embodiment, a liquid crystal polymer resin is used as the material of the flange 41. The left and right side plates 34 are fixed to the device frame 33 and form a frame of the fixing device 18.

Then, as shown in FIG. 2, the pressure spring 45 is reduced between the pressure portions of the left and right flanges 41 and the pressure arm 44. As a result, the left and right flanges 41, stays 40, and holders 38 are pressed against the lower surface of the pressurizing roller 32 with a predetermined pressing force with the film 36 sandwiched between them. In this embodiment, the pressure of the pressure spring 45 is set so that the pressure of the film 36 and the pressure roller 32 becomes 160 N in total pressure. By this pressurization, the holder 38 is pressed against the upper surface of the pressurizing roller 32 via the film 36, and a fixing nip portion N of about 6 mm is formed.

Then, a driving force from a drive source (not shown) is transmitted to the drive gear G of the pressure roller 32, and the pressure roller 32 is rotationally driven at a predetermined speed in the counterclockwise direction in FIG. Along with the rotation of the pressure roller 32, a rotational force acts on the film 36 due to the frictional force between the pressure roller 32 and the film 36 at the fixing nip portion N. As a result, the film 36 rotates the outer circumference of the holder 38 in the clockwise direction in FIG. 1 while its inner surface slides with the holder 38.

The recording material P is introduced into the fixing nip portion N after the film 36 is rotated by the rotation of the pressure roller 32, power is supplied to the conductive layer 36b, and the temperature of the film 36 reaches a predetermined temperature. The entrance guide 30 has a role of guiding the recording material P on which the toner image t in the unfixed state is formed toward the fixing nip portion N.

The recording material P carrying the unfixed toner image t is heated while being conveyed by the fixing nip portion N formed by the film 36 of the fixing nip portion N and the pressure roller 32, and the unfixed toner image t is fixed to the recording material P. Will be done.

The power feeding member (power supply member) 37 is for supplying power from the power source 50 to the conductive layer 36b, and is made of a conductive material such as metal or carbon. As shown in FIGS. 1 and 2, the power feeding member 37 is urged by an urging member such as a spring from the outer surface of the film 36 with respect to the electrode portions 361b at both ends of the film 36.

FIG. 5 is a schematic view showing the electrical connection of this fixing device. The power feeding members 37a and 37b provided at both ends of the film 36 are connected to the power supply 50 by a conducting wire, and the power supply 50 supplies power by a control unit (not shown).

When electric power is supplied to the conductive layer 36b from the feeding members 37a and 37b, the Joule heat generated by the current flowing through the conductive layer 36b causes the film 36 to rapidly rise in temperature. The temperature detection unit 42 measures the surface temperature of the film 36 in a non-contact manner. In this embodiment, a thermopile is used and the temperature detection unit 42 is arranged at a substantially central portion of the film 36 in the longitudinal direction. The surface temperature of the film 36 is detected by the temperature detection unit 42. The control unit controls the electric power supplied to the film 36 so that the detection temperature of the temperature detection unit 42 is maintained at the target temperature.

The length of the heat generating portion 362b in the longitudinal direction is provided so as to be longer than the maximum width of the recording material P. As a result, while giving sufficient heat to the entire area of the recording material P, unnecessary heat generation is suppressed in the electrode portion 361b through which the recording material P does not pass.

In this embodiment, the electrode portion 361b and the heat generating portion 362b are formed as an integral conductive layer 36b by printing silver ink which is the same material. In the electrode portion 361b, the conductive layer 36b is formed over the entire circumference of the film 36 in the circumferential direction of the film 36, whereas in the heat generating portion 362b, the conductive layer 36b has a width of about 0.5 mm and an interval of about 1.5 mm. It is formed in a thin line shape.

Here, when the electrode portion 361b and the heat generating portion 362b are formed of the same material, the electrode portion 361b also generates heat due to Joule heat. When the thickness of the electrode portion 361b and the heat generating portion 362b are the same, the resistivity ratio per unit length of the electrode portion 361b and the heat generating portion 362b in the longitudinal direction is proportional to the surface area of the conductive layer 36b, and thus is approximately 1: 4. .. That is, the electrode portion 361b is formed so that the surface area per unit length of the film 36 in the longitudinal direction is larger than that of the conductive layer 36b, and the resistance value of the electrode portion 361b is lowered. Therefore, when electric power is supplied to the conductive layer 36b, heat is generated in proportion to the resistance ratio thereof.

It is desirable to minimize the heat generated by the electrode portion 361b. The heat generated at the electrode portion 361b through which the recording material P does not pass not only lowers the energy efficiency, but also accumulates heat because the recording material P does not take heat, and damages peripheral members such as the film 36 and the power feeding member 37. This is because there is a risk of giving.

Therefore, in this embodiment, the electrode portion 361b and the heat generating portion 362b are simultaneously formed as an integral conductive layer (conductive pattern) 36b using the same material, and the thickness of the conductive layer 36b in the electrode portion 361b is set to the heat generating portion 362b. It is made thicker than the thickness of the conductive layer 36b in the above. By increasing the thickness of the conductive layer 36b in the electrode portion 361b, the resistance value of the electrode portion 361b is relatively lowered while the electrode portion 361b and the heat generating portion 362b are formed of the conductive layer 36b made of the same material. It becomes possible to suppress the amount of heat generated.

In this embodiment, the heat generating portion 362b is formed by printing once, whereas the electrode portion 361b is formed by printing twice. That is, the electrode portion 361b is printed on the electrode portion 361b formed in the first printing. As a result, the thickness of the electrode portion 361b is about twice as thick as that of the heat generating portion 362b, so that the resistance value per unit area of the electrode portion 361b is about half, and the calorific value is also about half in proportion to the resistance value. Become.

In this example, the surface resistivity when the heat generating portion 362b is printed once is a value measured by a method based on JIS K 7194 using Loresta GP (manufactured by Mitsubishi Chemical Analytech), and is 7.04 × 10. It is -1Ω / □. On the other hand, the surface resistivity when the heat generating portion 362b is printed twice is 3.61 × 10-1Ω / □, and the surface resistivity is about half.

An appropriate value should be selected for the surface resistivity of the heat generating portion 362b from the ratio of the width and the spacing of the thin line-shaped conductive layer 36b and the target value of the resistance value between both ends of the film 36. When the ratio of the thin line-shaped conductive layer 36 to the base layer 36a in the heat generating portion 362b in the circumferential direction of the film 36 becomes small, the heat generating area becomes small and the heat generation unevenness on the surface of the film 36 becomes large. On the other hand, if the ratio of the thin conductive layer 36b to the base layer 36a in the heat generating portion 362b is large in the circumferential direction of the film 36, the heat generation unevenness is improved, but the resistance values of the electrode portion 361b and the heat generating portion 362b are high. The difference becomes smaller, and the amount of heat generated by the electrode portion 361b increases. In this embodiment, in the heat generating portion 362b, the ratio of the length of the thin conductive layer 36b to the length of one circumference of the base layer 36a with respect to the circumferential direction of the film 36 is 1/4, and the resistance value between both ends of the film 36 is It is designed to be 18Ω. Considering both the uneven heat generation on the surface of the film 36 and the suppression of heat generation of the electrode portion 361b, the length of the thin conductive layer 36b with respect to the circumferential direction of the film 36 in the heat generating portion 362b with respect to the length of one circumference of the base layer 36a. The ratio of the heat is preferably 1/10 or more and 3/4 or less.

As a method of printing the electrode portion 361b twice, the pattern of the electrode portion 361b and the heat generating portion 362b shown in FIG. 6A is printed the first time, and the electrodes at both ends in the longitudinal direction of the film 36 are printed the second time. There is a method of printing only part 361b. Further, as another method, as shown in FIG. 6B, only the electrode portions 361b at both ends in the longitudinal direction of the film 36 are printed for the first time, and the patterns of the electrode portions 361b and the heat generating portion 362b are printed for the second time. May be printed. When printing the second time as shown in FIG. 6A, the second printing may be printed so as to overlap the electrode portion 361b of the first printing, or may be printed wider or narrower than the first printing. You may. When it is made wider than the first printing, the electrode portion 361b formed in the first printing can be reliably covered. On the other hand, when the size is narrower than that of the first printing, there is an advantage that the position of the boundary between the electrode portion 361b and the heat generating portion 362b can be easily controlled.

FIG. 7 shows this embodiment and a comparative example in which the electrode portion 361b is formed by printing only once and the thickness of the electrode portion 361b is the same as the thickness of the heat generating portion 362b. It is a graph of the amount. In the comparative example, the calorific value of the electrode portion 361b is about 1/4 of the calorific value of the heat generating portion 362b, whereas in this embodiment, it is suppressed to about 1/8. In contrast to the comparative example, in this embodiment, the resistance of the electrode portion 361b is low, so that it is possible to suppress heat generation at both ends.

As described above, according to the present embodiment, the electrode portion 361b and the heat generating portion 362b are integrally formed by using the same material, and the thickness of the electrode portion 361b is made thicker than the thickness of the heat generating portion 362b. , It is possible to suppress heat generation of the electrode portion 361b.

In this embodiment, the thickness is increased to about twice by printing only the electrode portion 361b twice, but it may not reach twice as thick depending on the printing method. In this case as well, the effect of reducing the amount of heat generated in the electrode portion is exhibited as the thickness increases.

(Second Example)
A second embodiment will be described with reference to FIGS. 8, 9, 10, 11, 12, and 13. 8 is a schematic cross-sectional view of the fixing device 18 in this embodiment, FIG. 9 is a front schematic view of the fixing device 18, FIG. 10 is a perspective view showing the configuration of the fixing roller 62, and FIG. 11 is a layered structure of the fixing roller 62. The cross-sectional view shown, FIG. 12, is a schematic view showing an electrical connection.

In this embodiment, the first embodiment is that the conductive layer 62d provided on the fixing roller 62 is heated instead of the film 36, and the heat generating portion 622d is formed over the entire circumference in the circumferential direction. different.

The same operation and configuration as in the first embodiment will be omitted, and only the points different from those in the above-described embodiment will be described here.

In this embodiment, as shown in FIGS. 8 and 9, the nip portion is formed with the fixing roller 62 on the upper side and the pressure film assembly 61 on the lower side. The electrode member 37 is provided on the holder 38, and the electrode member 37 is located outside the end portion of the pressure film 66 and supplies power to the fixing roller 62 from the outer surface.

The fixing roller 62 is formed by laminating a core metal 62a, a first elastic layer 62b, a resin layer 62c, a conductive layer 62d, a second elastic layer 62e, and a mold release layer 62f in this order.

FIG. 10 is a perspective view showing the configurations of the core metal 62a, the first elastic layer 62b, the resin layer 62c, and the conductive layer 62d of the fixing roller. In order to make the structure of the conductive layer 62d easy to understand, the second elastic layer 62e and the release layer 62f are partially omitted. 11A and 11B are cross-sectional views showing the layer structure of the fixing roller 62, FIG. 11A shows a cross-sectional view of the longitudinal end portion of the fixing roller 62, and FIG. 11B shows a cross-sectional view of the central portion. .. The second elastic layer 62e and the release layer 62f are not formed at the electrode portion, but are formed only at the heat generating portion. In order to make the structure easy to understand, the thickness ratio of each layer is different from the actual one.

In this embodiment, a first elastic layer 62b of a silicone rubber layer having a thickness of about 3.5 mm is formed on a core metal 62a having an outer diameter of 11 mm made of stainless steel by injection molding. Then, a resin layer 62c of a PI film having a thickness of about 60 μm was coated on the elastic layer 62b, and a conductive layer 62d having a thickness of about 2 μm was further formed on the resin layer 62c. Further, a second elastic layer 62e made of silicone rubber, fluororubber, or the like having a thickness of about 200 μm is formed on the layer, and a release layer 62f of a PFA coat layer having a thickness of about 15 μm is formed on the second elastic layer 62e. 62 was used. The second elastic layer 62e plays a role of lowering the hardness near the surface of the fixing roller 62 and improving the fixing property. The outer diameter of the roller is about 18 mm.

As shown in FIGS. 9 and 12, the second elastic layer 62e and the release layer 62f are not formed in the region of about 10 mm at both ends of the fixing roller 62 in the longitudinal direction, and the conductive layer 62d is exposed. .. The power feeding member 37 contacts the conductive layer 62d and supplies electric power to the conductive layer 62d.

The pressure film 66 has flexibility by forming a release layer on a base layer made of a heat-resistant resin. In this embodiment, a cylindrical polyimide base material having a thickness of about 60 μm is used as the base layer. The base layer was coated with a PFA resin tube having a thickness of about 15 μm as a release layer. In this embodiment, the film 66 has an inner diameter of about 18 mm.

In this embodiment, the conductive layer 62d is formed over the entire circumference in the entire longitudinal direction in this embodiment, and is formed by electroless nickel plating.

Therefore, if the thickness of the electrode portion 621d and the heat generating portion 622d in the conductive layer 62d are the same, the electrode portion 621d also generates heat equivalent to that of the heat generating portion 622d.

Therefore, in this embodiment, the thickness of the electrode portion 621d is set to be about 5 times that of the heat generating portion 622d. As a method of increasing the thickness, the plating formation time is lengthened only at the end portion. By increasing the thickness by about 5 times, as shown in FIG. 13, the amount of heat generated by the electrode portion 621d is reduced to about 1/5, and it is possible to suppress heat generation at the end portion.

Further, in this embodiment, since the inside of the conductive layer 62c is filled with the first elastic layer 62b as compared with the first embodiment, there is an advantage that the film 36 is less likely to be damaged as compared with the film 36 of the first embodiment. is there.

As described above, also in this embodiment, the electrode portion 621d and the heat generating portion 622d are integrally formed by using the same material, and the thickness of the electrode portion 621d is made thicker than the thickness of the heat generating portion 622d. , It is possible to suppress heat generation at the electrode portion 621d.

(Third Example)
A third embodiment will be described with reference to FIG. FIG. 14 is a longitudinal sectional view showing the structure of the film 76.

This embodiment is different from the first embodiment in that the thickness of the electrode portion is different.

The same operation and configuration as in the first embodiment will be omitted, and only the points different from those in the above-described embodiment will be described here.

Similar to the first embodiment, the film 76 is formed by laminating a base layer 76a, a conductive layer 76b, an elastic layer 76c, and a release layer 76d, and the conductive layer 76d is formed by printing silver ink. There is.

The conductive layer 76b is divided into an electrode portion 761b and a heat generating portion 762b in the longitudinal direction, and a region of the electrode portion 761b that comes into contact with the feeding member 37 is referred to as a feeding member contact portion 761b'.

Since the power feeding member contact portion 761b'contacts the power feeding member 37, it may be worn and the thickness may be reduced with the use of the fixing device 18.

Therefore, in this embodiment, the thickness of the electrode portion 761b is set to about twice the thickness of the heat generating portion 762b, and the thickness of the feeding member contact portion 761b'is set to about three times the thickness of the heat generating portion 762b.

By providing a difference in the thickness of the conductive layer 76b in the electrode portion 761b and making the thickness of the contact portion 761b'of the feeding member thicker, heat is generated in the electrode portion 761b even if the thickness of the contact portion 761b'is reduced. Can be suppressed.

The thickness of the electrode portion 761b may not be different and the entire thickness may be sufficient. However, if the difference in the thickness of the conductive layer 76b in the longitudinal direction is large, the difference in the rigidity of the film 76 becomes large and the difference in thickness is large. The film 76 may be damaged at the interface portion of the film 76. As in this embodiment, by providing a stepped difference in thickness, the difference in rigidity can be alleviated and damage to the film 76 can be suppressed.

In this embodiment, the thickness of the electrode portion 76b is changed in a stepped manner, but the difference in thickness may be different, such as providing an inclination in the thickness.

As described above, in the present embodiment, by providing a difference in the thickness of the electrode portion 76b and increasing the thickness of the feeding member contact portion 761b ′, even if the thickness of the contact portion 761b ′ is reduced, the electrode It is possible to suppress heat generation in the portion 761b.

As described above, in the first to third examples, silver ink and nickel plating have been used as the material of the conductive layer, but other materials such as metal and carbon may be used.

Further, although the embodiment in which the thickness of the conductive layer in the electrode portion is between about 2 times and 5 times that of the heat generating portion has been described, the thickness may be set outside this range. However, when the film has flexibility, it is desirable that the film is about 20 times as large as the heat generating portion in order to prevent the film from being damaged due to the difference in the thickness of the conductive layer.

(Fourth Example)
In Examples 1 to 3, the thickness of the electrode portion is made larger than that of the heat generating portion by using the same material as the configuration for suppressing the heat generation of the electrode portion in the film in which the electrode portion and the heat generating portion are formed of the conductive layer of the same material. A thickened configuration is shown.

In the fourth embodiment, an electrode layer formed of a material different from that of the heat generating portion is formed on the heat generating portion. The same operation and configuration as in the first embodiment will be omitted, and only the points different from those in the above-described embodiment will be described here.

FIG. 15 is a view showing a cross section of the film 36 in the longitudinal direction, and FIG. 16 is a view showing a cross section of the film 36 perpendicular to the longitudinal direction of the film 36.

In this embodiment, the thickness of the electrode portion 361b and the heat generating portion 362b of the conductive layer (first conductive layer) 36b is formed uniformly, and an electrode layer using a material different from that of the conductive layer 36b is used on the electrode portion 361b. It differs from the first embodiment in that (second conductive layer) 36e is provided. In this embodiment, the electrode portion 361b and the heat generating portion 362b are made of the same material to form an integral conductive layer 36b, but the present invention is not limited to this.

As shown in FIG. 15, the conductive layer 36b is divided into thin lines in the circumferential direction in the heat generating portion 362b as in the first embodiment. On the other hand, the electrode portions 361b provided at both longitudinal ends of the film 36 are formed in an annular shape extending in the circumferential direction, and the thickness thereof is about 10 μm, which is substantially the same as that of the heat generating portion 362b.

As shown in FIG. 16, the electrode layer 36e is formed on the conductive layer 36b and becomes the outermost layer at the end of the film 36. Further, the electrode layer 36e is formed to have a thickness of about 10 μm by applying silver ink having a higher silver compounding ratio than the conductive layer 36b. By increasing the blending ratio of silver, the volume resistivity of the electrode layer 36e becomes 0.2 μΩ · m, which is smaller than the volume resistivity of 4.2 μΩ · m of the conductive layer 36b. By sufficiently lowering the volume resistivity of the electrode layer 36e, it is possible to suppress heat generation of the electrode layer 36e.

Further, by forming the electrode layer 36e on the annular electrode portion 361b, the electrode layer 36e has a surface with less unevenness in the circumferential direction, and it is possible to secure good contact with the feeding member 37. ..

As described above, in the present embodiment, by forming the electrode layer 36e on the electrode portion 361b of the conductive layer 36b, good contact with the power feeding member 37 is suppressed while suppressing heat generation at the end portion of the film 36. It becomes possible to secure the sex.

(Fifth Example)
In Example 5, the electrode layer 36e is formed to the inside of the boundary between the electrode portion 361b and the heat generating portion 362b. The same operation and configuration as in the first embodiment will be omitted, and only the points different from those in the above-described embodiment will be described here.

FIG. 17 is a diagram showing a cross section in the longitudinal direction showing the structure of the film 36. In this embodiment, the electrode layer 36e using a material different from the conductive layer 36b is partially applied not only on the annularly formed electrode portion 361b but also on the finely formed heat generating portion 362b. It is provided. That is, the electrode layer 36e is different from the fourth embodiment in that the electrode layer 36e is formed so as to overlap the boundary between the heat generating portion 362b and the electrode portion 361b.

By forming the electrode layer 36e to the inside of the boundary between the electrode portion 361b and the heat generating portion 362b, it is possible to further suppress the disconnection of the conductive layer 36b due to stress applied to the boundary between the electrode portion 361b and the heat generating portion 362b. Play. However, since the heat generating portion 362b formed in a fine line shape tends to have an uneven shape in the circumferential direction, it is preferable that the region in contact with the power feeding member 37 is on the electrode portion 361b.

As described above, in this embodiment, in addition to the effects of the fourth embodiment, it is possible to suppress disconnection of the conductive layer 36b due to stress applied to the boundary between the electrode portion 361b and the heat generating portion 362b. ..

In the first to third embodiments, the same material is used to make the electrode portion thicker than the heat generating portion, and in the fourth and fifth embodiments, the heat generating portion is formed. The structure in which the electrode layer made of a material different from the above was formed was described.

The method of forming the electrode portion using the same material as the heat generating portion has an advantage that the manufacturing process can be simplified because the electrode portion and the heat generating portion can be integrally formed. On the other hand, the method of forming the electrode portion using a material different from that of the heat generating portion has an advantage that a material suitable for the electrode portion can be freely selected. Further, by combining these methods, it is possible to suppress the heat generation of the electrode portion more effectively. Further, in the fourth and fifth embodiments, the application of silver ink has been described as a method for forming the electrode layer, but other conductive materials such as metal and carbon may be used, and the forming method is also printed. , Plating, sputtering, vapor deposition and the like.

18 Fixing device 36 Film 36a Base layer 361a Electrode part 361b Electrode part 362b Heat generation part 36e Electrode layer 37 Feeding member

Claims (10)

A tubular film used for fixing devices,
With the base layer
An electrode portion formed at an end portion of the base layer in the longitudinal direction of the film, and an electrode portion.
A heat generating portion formed in the central portion of the base layer in the longitudinal direction of the film and electrically connected to the electrode portion, and a heat generating portion.
The electrode portion and the heat generating portion are formed of a conductive layer made of the same material.
Than said direction of the electrode portion is the heat generation unit rather thick thickness of the conductive layer,
The electrode portion is a portion formed by the annular conductive layer extending in the circumferential direction of the film, and the heat generating portion is a thin linear conductive layer extending in the longitudinal direction of the film around the film. A film characterized in that it is a portion formed by arranging a plurality of portions at intervals from each other in terms of direction. The film according to claim 1, wherein the electrode portion has a larger surface area of the conductive layer per unit length in the longitudinal direction of the film than the heat generating portion. The heat generating portion is characterized in that the ratio of the length of the conductive layer formed to the length of one circumference of the base layer in the circumferential direction of the film is 1/10 or more and 3/4 or less. The film according to claim 1 or 2. A tubular film, the base layer, an electrode portion formed at the end of the base layer in the longitudinal direction of the film, and an electrode portion formed in the center of the base layer in the longitudinal direction of the film and electrically. A film having a heat generating part connected to the
A power supply member for supplying electric power to the heat generating portion conductive contact with the electrode layer through the electrode portions,
The film generates heat by the current flowing through the heat generating portion, and the heat of the film fixes the toner image to the recording material.
Said electrode portion, and the heat generating portion, is formed of a conductive layer of the same material, toward said electrode portion is rather thick thickness of the conductive layer than the heating part,
The electrode portion is a portion formed by the annular conductive layer extending in the circumferential direction of the film, and the heat generating portion is a thin linear conductive layer extending in the longitudinal direction of the film around the film. A fixing device characterized in that it is a portion formed by arranging a plurality of portions at intervals from each other in terms of direction. The fixing device according to claim 4 , wherein the electrode portion has a larger surface area of the conductive layer per unit length in the longitudinal direction of the film than the heat generating portion. The heat generating portion is characterized in that the ratio of the length of the conductive layer formed to the length of one circumference of the base layer in the circumferential direction of the film is 1/10 or more and 3/4 or less. The fixing device according to claim 4 or 5. A method for producing a film having a tubular base layer and a conductive pattern formed on the base layer and used for a fixing device.
A first step of printing the conductive pattern on the edges and the center of the base layer in the longitudinal direction of the film over the circumferential direction of the film.
A method for producing a film, which comprises a second step of printing the conductive pattern over the circumferential direction of the film by superimposing it only on the end portion of the conductive pattern formed in the first step. A method for producing a film having a tubular base layer and a conductive pattern formed on the base layer and used for a fixing device.
The first step of printing the conductive pattern over the circumferential direction of the film only on the end portion of the base layer in the longitudinal direction of the film.
The conductive pattern is printed over the circumferential direction of the film on the conductive pattern formed at the end portion of the base layer, and at the same time, the conductive pattern is printed at the central portion in the longitudinal direction of the film over the circumferential direction of the film. The second step of printing the conductive pattern and
A method for producing a film, which comprises. A tubular film used for fixing devices,
With the base layer
An electrode portion formed at an end portion of the base layer in the longitudinal direction of the film, and an electrode portion.
A heat generating portion formed in the central portion of the base layer in the longitudinal direction of the film and electrically connected to the electrode portion, and a heat generating portion.
The electrode portion and the heat generating portion are formed of a first conductive layer made of the same material.
A second conductive layer having a volume resistivity lower than that of the first conductive layer is formed on the electrode portion .
A film characterized in that, in the longitudinal direction of the film, the second conductive layer is formed so as to overlap the boundary between the heat generating portion and the electrode portion . The electrode portion is a portion formed by the annular first conductive layer extending in the circumferential direction of the film.
The heat generating portion is a portion formed by arranging a plurality of the first conductive layers having a thin line extending in the longitudinal direction of the film at intervals with respect to the circumferential direction of the film.
The film according to claim 9.

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