JP2006145949A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device that ensures efficient workability, sustains strength and assures high heat efficiency. <P>SOLUTION: The fixing device includes: an excitation coil and a coil holder, made of a resin, for holding the excitation coil; a magnetic flux generating means having a plurality of magnetic cores; and an induction heat generating body for generating heat by electromagnetic induction caused by a magnetic flux generated by the magnetic flux generating means. The fixing apparatus applies thermal energy, produced by heat generated by the induction heat generating body, to a material, such as paper, which is heated while conveyed. In the fixing device, each of the magnetic cores is a core unit formed by causing a liquefied resin to flow so as to integrally cover a core with gaps G formed. The excitation coil is held in the coil holder in such a way as to remain a predetermined distance apart from the induction heat generating body. The coil holder is composed in combination with the core unit such that the excitation coil and the magnetic coil are disposed with a predetermined distance between them. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electromagnetic induction heating type fixing device.

  Patent Document 1 discloses an induction heating fixing device that induces a current in a fixing roller by magnetic flux and generates heat by Joule heat. This makes it possible to directly heat the fixing roller by using the generation of induced current, and achieves a fixing process that is more efficient than a heat roller type fixing device using a halogen lamp as a heat source.

  However, since the energy of the alternating magnetic flux generated by the exciting coil as the magnetic field generating means is used for raising the temperature of the entire fixing roller, the heat dissipation loss is large, and the density of the fixing energy relative to the input energy is low and the efficiency is low.

  In view of this, proposals have been made regarding an improved configuration of the magnetic flux generation means as in Patent Document 2 for higher efficiency and a manufacturing method for achieving higher efficiency as in Patent Document 3.

  Moreover, in order to reduce manufacturing cost, the proposal regarding the manufacturing method which adhere | attaches between several cores like patent document 4 is made | formed.

Japanese Utility Model Publication No. 51-109737 JP-A-9-292786 JP 2003-066842 A Japanese Patent Laid-Open No. 11-311910

  However, with regard to the electromagnetic induction heating type fixing device, in order to ensure the fixing quality at higher speeds, the supply of more power causes a problem of self-heating of the exciting coil, and further improvement in efficiency must be achieved. I must.

  In addition, since the magnetic core is a member that can be molded only with a relatively rough dimension, play occurs at the time of assembly and it is difficult to incorporate the magnetic core into a normal position, so that a desired output cannot be obtained.

  Moreover, in the invention described in Patent Document 4, in order to secure the manufacturing cost equivalent to the integral molding, it is bonded with an adhesive only for the cross section of each core, but the core cross section area is small, so the strength of the core is reduced. Since it takes time to assemble very much by bonding one by one, and it takes time to harden the adhesive, there are problems such as inefficiency in work efficiency and cost. In addition, a decrease in core life due to adhesive deterioration due to high temperature is also a problem.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a highly heat-efficient fixing device that has good workability and can maintain strength.

  In order to achieve the above object, the present invention provides an electromagnetic coil by the action of an exciting coil, a resin coil holder for holding the exciting coil, magnetic flux generating means having a plurality of magnetic cores, and magnetic flux generated by the magnetic flux generating means. In the fixing device having an induction heating element that generates induction heat, and applying heat energy generated by heat generation of the induction heating element to a heated material such as paper to be conveyed, the plurality of magnetic cores are in a state in which a gap G is formed. A liquefied resin is poured so as to cover each core and is configured as an integrally molded core unit, and the exciting coil is attached to the coil holder so as to maintain a predetermined distance from the induction heating element. The coil holder is configured to be combined with the core unit so that the excitation coil and the magnetic core are arranged at a predetermined distance. And butterflies.

  According to the present invention, since the integrally formed core holder takes several tens of seconds until the resin hardens in the mold, the core holder can be completed in a very short time compared to fixing with a conventional adhesive. Can do. In addition, since the first magnetic core is covered with the upper half of the resin and the second magnetic core is entirely covered with the resin, the integrally formed core unit is bonded only to the conventional core cross-section with an adhesive. The structure is very strong compared to the type.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1>
The configuration of the magnetic core 111 according to the present invention will be described with reference to FIG.

  The magnetic core 111 has a hole in the center of the surface, and the first magnetic core 111a is placed on a T-shaped horizontal portion by a fixing pin (not shown), and the second magnetic core 111b is It is fixed to the vertical part of the T-shape. Then, a plurality of the T-type cores are arranged in parallel with a predetermined gap G, and temporarily fixed in a mold (not shown). In the present invention, the magnetic cores 111 are arranged at intervals of G1 = 0.3 mm and G2 = 3.5 mm.

  In FIG. 2, the manufacturing method of the core unit 113 according to the present invention will be described.

  By injecting a liquefied resin (LCP) into a plurality of temporarily assembled magnetic cores 111 set in the mold, the first magnetic core 111a is entirely surrounded by the second magnetic core. In 111b, the resin flows into the hole in the center of the upper half of each core surface, and the cores are fixed to each other.

  Further, the resin is also formed into a guide shape of a rotating magnetic shielding plate (not shown) and a coil guide shape that causes the exciting coil 101 to be in close contact with the coil holder, and fulfills functions other than fixing the core. As described above, the magnetic core 111 is integrally formed as the core unit 113.

  The core holder that is integrally molded in the above process takes several tens of seconds until the resin hardens in the mold, so that the core holder can be completed in a very short time compared to fixing with a conventional adhesive. Can do. Also, since the first magnetic core 111a is entirely covered by the resin, the second magnetic core 111b is covered in the upper half, and the hole at the center of each core surface is covered, the integrally formed core unit 113 is Compared to the conventional type in which only the core cross section is bonded with an adhesive, the structure is very strong.

  When the gap G between the cores exceeds 5 mm, the magnetic flux generation distribution becomes non-uniform in the longitudinal direction, and the temperature distribution of the fixing roller, which is an induction heating element, becomes non-uniform, and the fixability may deteriorate.

Therefore, in the present invention, G1 = 0.3 mm and G2 = 3.5 mm.
0mm ≦ G ≦ 5mm
It becomes essential.

  The configuration of the coil holder 108 and the magnetism generating unit 112 according to the present invention will be described with reference to FIGS.

  In the coil holder 108, the exciting coil 101 is set inside, and the core unit 113 that is integrally molded is fitted from above, and both ends are screwed to complete the magnetic flux generating unit.

Here, the exciting coil 101 and the magnetic core 111 will be described. The coil 1 must generate an alternating magnetic flux sufficient for heating. For this purpose, it is necessary to make the resistance component low and the inductance component high. . As a core wire of the exciting coil 101, a litz wire in which about 80 to 160 fine wires having a diameter of 0.1 to 0.3 mm are bundled is used. Insulated coated wires are used for the thin wires. In addition, an exciting coil 101 that is wound 8 to 12 times around the magnetic core 111 is used. An excitation circuit is connected to the excitation coil 101 so that an alternating current can be supplied to the excitation coil 101.

  As the magnetic core 111, it is preferable to use a material having a high magnetic permeability residual magnetic flux density such as ferrite, but it is not particularly limited as long as it can generate a magnetic flux. The present invention does not define the shape and material of the magnetic core 111, and the first magnetic core 111a and the second magnetic core 111b are integrally formed into a T shape to obtain the effects of the present invention. be able to.

  Next, a fixing device of a general image forming apparatus will be described with reference to FIG. 5 as a heating apparatus provided with the coil unit 110.

  The fixing roller 100 is made of an iron core having a thickness of 1 mm, and has an outer peripheral length of 35 mm and a total length of 350 mm.

  A pressure roller 104 that is in pressure contact with the fixing roller 100 and a nip 117 are formed to fix the toner to the paper.

  In the pressure roller 104, 5 mm of silicon rubber is disposed on a 3 mm thick iron core, and a 50 μm thick PFA tube is disposed on the outer periphery thereof.

  The sheet material conveyed by the sheet material feeding means and onto which the toner image is transferred is transferred to the fixing device 102 having the fixing roller pair 119 including the fixing roller 100 and the pressure roller 104 having the above-described configuration by the fixing inlet guide 118. The nip portion 117 is entered.

  Here, the toner image on the sheet material is fixed on the sheet material. In this embodiment, the gaps G1 and G2 between the cores are fixed. However, when the fixing device is a system in which the temperature at the end of the fixing roller 100 decreases, the gaps G1 and G2 between the cores or By setting both G1 and G2 to 0 mm at the end and 4 mm at the center, the magnetic flux generation density at the end of the core holder can be increased and the magnetic flux generation density at the center can be reduced. The temperature drop can be improved.

  As described above, it is possible to obtain a more optimal fixing device by changing the interval between the cores in the longitudinal direction.

It is a perspective view of a magnetic body core. It is a perspective view of a core unit. It is a perspective view of a coil unit. It is a perspective view of a magnetic generation unit. Overview of fixing device

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Fixing roller 101 Excitation coil 102 Fixing device 104 Pressure roller 108 Coil holder 109 Core holder 110 Coil unit 111 Magnetic body core 111a 1st magnetic body core 111b 2nd magnetic body core 112 Magnetic generation unit 113 Core unit 117 Nip 118 Entrance Guide 119 Fixing roller pair

Claims (7)

An excitation coil, a resin-made coil holder that holds the excitation coil, a magnetic flux generation means having a plurality of magnetic cores, and an induction heating element that generates electromagnetic induction heat by the action of the magnetic flux generated by the magnetic flux generation means are conveyed. In a fixing device that applies heat energy generated by the heat of the induction heating element to a heated material such as paper,
The plurality of magnetic cores are configured as integrally formed core units in which resin liquefied in a state where the gap G is formed is poured so as to cover each core, and the exciting coil is configured to generate the induction heat. The coil holder is held so as to maintain a predetermined distance with respect to the body, and the coil holder is combined with the core unit so that the exciting coil and the magnetic core are arranged at a predetermined distance. A fixing device characterized by comprising: The gap G is 0 mm ≦ G ≦ 5 mm
The fixing device according to claim 1, wherein: The magnetic core is disposed in a T shape by a first magnetic core and a second magnetic core, and the first magnetic core is disposed in a T-shaped horizontal portion, and each of the first magnetic bodies The core is formed to maintain a gap G1, the second magnetic core is disposed in a T-shaped vertical portion, and each of the second magnetic cores is formed to maintain a gap G2.
0mm ≦ G1, G2 ≦ 5mm
The fixing device according to claim 1, wherein the fixing device has the following relationship.   The fixing device according to claim 1, wherein each gap G <b> 1 of the plurality of first magnetic cores is constant.   The fixing device according to claim 1, wherein a distance G <b> 2 between the plurality of second magnetic cores is constant.   4. The fixing device according to claim 1, wherein the intervals G <b> 1 of the plurality of first magnetic cores are not constant in order to change a heat generation distribution of the induction heating element.   7. The fixing device according to claim 1, wherein the intervals G <b> 2 of the plurality of second magnetic cores are not constant in order to change the heat generation distribution of the induction heating element.

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