JPH0592990U - Tubular heater - Google Patents

Abstract

(57) [Summary] [Purpose] A planar heater on the inner wall of a tubular object to prevent uneven temperature on the heating surface of the photosensitive drum or exposure drum of dry electrophotographic copying machines, printers using semiconductor laser dry electrophotography, etc. A cylindrical heater that can be attached with the entire surface in close contact is obtained. [Structure] The two non-heat-generating portions of the planar heating element that face each other are bent at the boundary with the heat-generating portion, and are wound in a tubular shape so that the bent portions are inside, and the bending ends are fixed to each other if necessary Then, it is used as a tubular heater, which is inserted into a tubular object and mounted.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a tubular heater, and more particularly to a tubular heater capable of uniformly heating a tubular member of a photoconductor drum or an exposure drum of a copying machine, a semiconductor laser dry electrophotographic printer or the like from the inside.

[0002]

[Prior Art]

 When a flat sheet heating element is rolled into a cylinder and inserted into a tubular object, the difference between the expansion and contraction of the outer surface and the inner surface is shown in Fig. 4. As shown, a space 9 is formed between the peripheral portion of the sheet heating element 3 including the non-heating portion (insulation allowance) 4 and the inner wall of the tubular object 8. Therefore, the entire surface of the heating element should be in close contact with the tubular object. I can't. Therefore, when the tubular material is heated, there is a disadvantage that a temperature difference is partially generated on the surface of the tubular material and uneven printing occurs.

Conventionally, as a method for solving such a problem, metal fittings attached to non-heating portions of two opposite sides of a planar heating element are joined together to form a tubular shape so that the fitting is tightly attached to a tubular object. A cylindrical body made of synthetic resin or metal with a diameter larger than that of the tubular object to be inserted, and cut it out so that the cross section becomes an arc, and use adhesive, double-sided tape, etc. on this inner surface. Attaching a sheet heating element and inserting it into a tubular object, and using the force of the tubular body to open it, it makes close contact with the tubular object. A cylinder with a diameter corresponding to the inner diameter of the photosensitive drum is cut in the spiral direction. A planar heating element in which a heating element having a heating circuit surface pre-insulated on one side of a substrate formed of a parallelogram-shaped elastic material substantially corresponding to the shape cut by a line and developed (Japanese Patent JP-A-60-254587) is proposed. .

[0004]

[Problems to be solved by the device]

 However, when the metal fittings are used, the weight becomes heavy, and not only the planar heating element is required to have the strength to withstand the weight of the metal fittings, but also the metal fittings easily damage the tubular object, and a protective material for this is required, which results in cost There are drawbacks such as being expensive. In addition, when a cylindrical body made of synthetic resin is used, the cost becomes high and the heat of the planar heating element is transferred to the tubular object of the object to be heated through the tubular body. It takes time to raise the temperature of the tubular product, and power consumption also increases. Further, the planar heating element proposed in Japanese Patent Laid-Open No. 60-254587 not only requires complicated processing due to the shape of the parallelogram, but also has a uniform heating over the entire surface, which is said to have the best heating efficiency. It is difficult to get fever. This is because, when a heating element is provided on the entire heating range, the electrodes are usually placed in the vicinity of two opposite sides of the parallelogram, and when a voltage is applied, a current flows between the electrodes. Since a large amount of gas flows in the shortest distance, uniform heat generation cannot be obtained over the entire surface.

[0005]

[Means for Solving the Problems]

 The inventor of the present invention has solved these problems, and as a result of earnest research to obtain a tubular heater having a simple structure and capable of reliably adhering the entire heating surface to the inner wall of the tubular object, the non-heating part of the planar heating element is found. The present invention has been completed, focusing on the utilization of the physical properties of. That is, the present invention relates to a tubular heater for inserting and mounting a tubular object and heating the tubular object from the inside, in which a non-heating part of a planar heating element having a non-heating part in the periphery is provided on two opposite sides of the non-heating part. A tube characterized by bending each in the same direction along a line parallel to the boundary with the heat generating section, and winding the planar heating element in a tubular shape so that the bent section is on the inside. It is a heater. The cylindrical heater of the present invention is used by being mounted inside an object having a tubular structure such as a photoconductor drum such as a copying machine or a semiconductor laser dry electrophotographic printer, an exposure drum, and a heat retaining roll of a laminator. ..

In the present invention, the sheet heating element used for the tubular heater is not particularly limited in its type as long as it has flexibility and restoring elasticity to be wound in a tubular shape. For example, carbon black and Carbon made by polymerizing vinyl-based synthetic resin monomers and adding epoxy cross-linking agent and, if necessary, metal powder, etc. into a paint by impregnating it into a cloth such as glass cloth by heat treatment. A black graphite polymer surface heating element, a carbon black graft polymer surface heating element that has been heat-treated after printing on a synthetic resin film by a printing method using the same paint or printing ink, and a synthetic resin substrate. A surface heating element in which metal foil such as fixed stainless steel foil, nichrome foil, copper nickel foil, etc. is patterned and wiring by etching method. Alternatively, there is a surface heating element in which metal resistance wires such as nichrome, copper nickel, and iron chrome are wired on a synthetic resin substrate and fixed with an adhesive or adhesive tape. Among these, a carbon black graft polymer-based surface heating element in which glass cloth is impregnated, heat-cured, or similar paint or printing ink is preferable. Both sides of the surface heating element are covered with an insulating film such as polycarbonate that has an area of a size that can take an insulation allowance around the periphery, and electrodes are attached to this to form a planar heating element. The cost is the non-heating part in the present invention. The planar heating element is used by bending the two non-heating parts facing each other along the boundary line with the heating part. If desired, the bent non-heat generating portion may be partially provided with a concave cutout portion inward from the peripheral edge of the non-heat generating portion.

In the present invention, the tubular object to which the planar heating element is attached is cylindrical, and its size is not particularly limited. For example, in the case of a photosensitive drum or an exposure drum, it is usually in the long axis direction. Has a length of 50 to 400 mm and an inner circumference of 60 to 800 mm.

The shape and size of the sheet heating element used in the present invention vary depending on the application, use conditions, etc. and cannot be specified unconditionally, but it is usually rectangular or square, and its size and insulation width are It is determined according to the length and inner circumference of the tubular object to be attached. That is, generally, when the sheet heating element is wound in a tubular shape, the length of the side in the long axis direction is equal to or shorter than the length of the tubular object. On the other hand, the length of the side wound around the circumference is shorter than the inner circumference of the tubular object, and the total length including the non-heat generating section is longer than the inner circumference of the tubular object. Is designed to be. Therefore, if the tubular heater has the above-mentioned dimensions, the tubular heater attached to the tubular heater has a longitudinal length of 50 to 400 mm, a tubular circumference of 60 to 800 mm, and a non-heat generating portion. Has a width of about 10 to 50 mm and is selected so as to satisfy the above-mentioned conditions.

In the present invention, when the planar heating element is formed into a tubular shape, the two non-heating portions facing each other in the major axis direction are bent toward the inside of the tube along the vicinity of the boundary with the heating portion. After that, the planar heating element is rolled into a tubular shape so that the peripheral edges of the non-heating portion facing each other contact or come close to each other to form a tubular heater. The tubular heater may be installed by inserting it into a tubular object as it is, but in order to prevent the shape from becoming deformed and facilitate the insertion operation, fix it with the peripheral edges of the bent non-heating parts close to or joined to each other. Is preferred. As a fixing method, an adhesive, an adhesive tape, or the like may be used, and a metal fitting such as a clip or a hook, or a mechanical means such as sewing may be used.

Next, the present invention will be illustrated with reference to the drawings, and the operation thereof and the like will be described more specifically. FIG. 1 is a perspective view of a planar heating element, FIG. 2 is a perspective view of a tubular heater of the present invention, and FIG. 3 is a perspective view showing a state where the tubular heater is attached to a tubular object. In FIG. 1, the peripheral insulating margin of a rectangular sheet heating element 3 in which both surfaces of a surface heating element to be the heating section 1 are covered with two insulating coating materials 2 is a non-heating section 4. The long-side non-heat generating portions 4 and 4 facing each other are bent along the vicinity of the boundary with the heat generating portion 1.

In FIG. 2, when the planar heating element 3 shown in FIG. 1 is wound so that the non-heat generating portions 4 and 4 are folded inward, the entire heat generating portion 1 including the vicinity of the bent portion swells in a round shape to form a tubular shape. Becomes The bent non-heat generating parts 4 and the peripheral edges 5, 5 of the four facing each other are in contact with each other. In this state, the non-heat generating parts are fixed by the adhesive tapes 6, 6, 6 to form the cylindrical heater 7 of the present invention. Has become.

In FIG. 3, the tubular heater 7 shown in FIG. 2 is inserted into the tubular member 8 as it is because the radius of the tubular heater 7 becomes smaller when a force is applied so that the bent portions of the tubular heater 7 come closer to each other. Can be installed. The cylindrical heater 7 inserted inside has a round bulge around the heat-generating part 1 due to the bending of the non-heat-generating part 4, and has a synergistic effect with the inherent resilience which tends to spread outside the planar heat-generating body 3. It spreads due to the action, and the entire surface of the heat generating portion 1 is in a state in which it is in close contact with the inner wall of the tubular object 8 without fail.

[0013]

【Example】

In a form similar to that shown in FIG. 1, both sides of a carbon black graft polymer surface heating element having a thickness of 0.1 mm are insulation-coated with a polycarbonate sheet having a thickness of 0.2 mm, and the temperature is 175 ° C. and the pressure is 5 kg / cm ² . After integrally molding, the periphery is cut, and a rectangular rectangular sheet heating element of 314 mm in length and 246 mm in width has a width of 20 mm in each of two non-heating portions facing in the vertical direction and two sides in the horizontal direction facing each other. A 90 W planar heating element having a non-heating portion width of 5 mm was manufactured. Bend the two non-heat-generating parts of the sheet heating element that face each other in the vertical direction along the boundary with the heat-generating part so that the bending angle is 100 degrees and the radius R of the bent part is about 2 mm. After that, this non-heat-generating portion is wound in a tubular shape so that the non-heat-generating portion enters inside, and the non-heat-generating portions are fixed with a polyester adhesive tape to obtain a cylindrical heater similar to that shown in FIG.

The tubular heater was inserted into and mounted on an aluminum tubular product having a length of 360 mm and an inner diameter of 73 mm. As a result, as shown in FIG. 3, it was confirmed that the entire heating portion of the tubular heater was in close contact with the inner wall of the tubular object. When the tubular heater was energized in this state and the temperature of each part of the surface of the tubular object was measured, it was 50 ± 3 ° C., and there was almost no temperature unevenness, and the entire surface was heated uniformly.

[0015]

EFFECTS OF THE INVENTION The present invention is a tubular heating element that utilizes the physical characteristics of the sheet heating element and its non-heating portion, and is mounted so that the front surface of the heating portion is firmly attached to the inner wall of the tubular object. The heat efficiency is high, and the surface of the tubular article can be heated uniformly without causing temperature unevenness. In addition, it suffices to bend the non-heat-generating part of the planar heating element, does not require any complicated parts at all, is easy to process, and is easy to attach to a tubular object, which is not only economical, It has many excellent characteristics in practical use, such as the fact that it can be used as it is as a material having electrical insulation, heat resistance, and difficult twisting as specified in the Electrical Appliance and Material Control Law and overseas standards such as UL, CSA, and VDA. is there.

[0016]

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a planar heating element in which a non-heating portion is bent.

FIG. 2 is a perspective view of a tubular heater.

FIG. 3 is a perspective view showing a state where a tubular heater is mounted inside a tubular object.

FIG. 4 is a perspective view of the sheet heating element wound into a tubular shape and mounted on a tubular object.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat generating part 2 Insulation coating material 3 Sheet heating element 4 Non-heat generating part 5 Periphery 6 Adhesive tape 7 Cylindrical heater 8 Tubular object 9 Space part

Claims (3)

[Scope of utility model registration request] 1. A tubular heater for inserting a tubular object into a tubular object to heat the tubular object from the inside thereof, wherein a planar heating element having a non-heating element in the periphery of two non-heating elements facing each other. A cylinder characterized by bending each in the same direction along a line parallel to the boundary with the heat generating part, and winding the planar heating element in a cylindrical shape so that the bent part is on the inside. Shaped heater. 2. The tubular heater according to claim 1, wherein the tubular heater is fixed by an adhesive, an adhesive tape or mechanical means so that the peripheral edges of two opposite sides are in contact with each other. 3. The width of the non-heat generating portion to be bent is 10 to 10.
The cylindrical heater according to claim 1, which has a length of 50 mm.