JP2005043741A - Image fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image fixing device which prevents mispositioning by thermal impact, is easily disassembled and therefore recycled, and generates pressurizing force to a member to be heated by applying tension to a planar heating element. <P>SOLUTION: In the image fixing device using the planar heating element constituted by holding a laminar heater between heat resistant sheets, an expansion section is wound around a supporting member to be mounted with the planar heating element and is fixed thereto. Since the planar heating element can be fixed without using an adhesive, the mispositioning by the thermal impact is prevented and in addition, the device is easily disassembled and is therefore recycled. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image fixing apparatus that heats a material to be heated at a pressure nip portion between a heating body and a pressure member.

  As a specific example of a heating device that heats a material to be heated at a pressure nip portion between a heating member and a pressure member, image fixing by a heat roller method in an image forming apparatus such as an electrophotographic printer, an electrophotographic copying machine, or an electrostatic recording apparatus There is a device.

  This is basically composed of a heating roller (fixing roller) as a heating body and a pressure roller as a pressure member brought into pressure contact with the heating member, and the pair of rollers are rotated so that the pressure nip ( Introducing a recording material (transfer material sheet, electrostatic recording paper, resin transparent sheet, printing paper, etc.) as a heated material on which an unfixed image (toner image) is formed and supported in the fixing nip portion) By sandwiching and passing the portion, the unfixed image is fixed to the surface of the recording material as a permanently fixed image by heat and pressure by the heat of the heating roller and the pressure of the pressure nip portion.

  In the heat roller method, the heating roller with a surface heating type roller has high energy efficiency, and the surface temperature rises quickly, so that it can be quickly raised from room temperature to fixable temperature during printing. It is an energy-saving device that can reduce power consumption to zero.

  Also, a film heating type apparatus has been put to practical use as another energy saving type heating apparatus or image heating fixing apparatus. This is proposed in, for example, Patent Documents 1 to 16, and the like, in which a heat-resistant film (fixing film) is brought into close contact with a heating member by a pressure member and slid and conveyed, and the heating member and the pressure are sandwiched between the heat-resistant films. The material to be heated is introduced between the heat-resistant film of the pressure nip formed by the member and the pressure member, and the pressure nip is transported together with the heat-resistant film, so that the heat of the heating body is reduced. It is an apparatus provided to a to-be-heated material via.

  A film heating type image fixing device can use a low heat capacity linear heating element as a heating element and a thin film with a low heat capacity as a heating element, thus saving power and shortening the wait time (quick start). In addition, the temperature rise in the apparatus can be suppressed, and the image fixing apparatus has an advantage that an offset can be prevented because a fixing point and a separation point can be set separately.

  In addition, it is possible to alleviate or prevent the occurrence of temperature rise at the non-sheet-passing portion to solve the problem due to temperature rise at the non-sheet-passing portion, and to solve the problem due to thermal expansion of the pressure member. There is Patent Document 17 as an object (FIG. 8). This is because the heating body 101 supported by the frame 7 has elasticity, and a pressing nip portion N having a predetermined width is formed between the heating body 101 and the pressure member M by elastic deformation of the heating body 101. The heating device 105 heats the heated body 105 and the recording material 104 to fix the image.

JP-A-63-313182 Japanese Patent Laid-Open No. 2-157878 JP-A-4-44075 JP-A-4-44076 JP-A-4-44077 JP-A-4-44078 JP-A-4-44079 JP-A-4-44080 JP-A-4-44081 JP-A-4-44082 JP-A-4-44083 JP-A-4-204980 JP-A-4-204981 JP-A-4-204982 JP-A-4-204983 JP-A-4-204984 Japanese Patent Laid-Open No. 7-5784

  In an image fixing apparatus that heats a material to be heated at a pressure nip portion between a heating body and a pressure member, such as the above-described heat roller system and film heating system, conventionally, the pressure member for the heating body is an elastic body such as a heat-resistant rubber. A pressure nip portion having a predetermined width is formed between the pressure elastic body roller and the heating body by elastic deformation of the roller.

  However, an elastic roller such as a heat-resistant rubber as a pressure member has poor heat conductivity and a large coefficient of thermal expansion, and has the following problems.

  That is, in an image fixing device of a heat roller method or a film heating method, when a heating material having a width smaller than that of the heating body (small size heating material) is continuously introduced and subjected to heat treatment, The portion where the non-heating material does not pass on the heating body becomes high temperature (non-sheet-passing portion temperature rise phenomenon), and the deterioration of the apparatus is accelerated. In particular, an elastic roller made of heat-resistant rubber or the like as a pressure member has poor thermal conductivity, and is one of the major causes for promoting the temperature rise phenomenon of the non-sheet passing portion.

  In particular, in a heat roller type image fixing device or a film heating type heating device using a surface heating type heating roller, heat conduction in the longitudinal direction of the pressure nip portion of the pressure member (fixing roller, fixing film) is poor. In addition, the temperature rise at the non-sheet passing portion is increased, and it is easy to give a thermal shock to components in the vicinity of the heating member such as a pressure elastic roller and a bearing.

  If the temperature rise of this non-sheet passing part temperature rise is significant, then the non-sheet passing part temperature rises when a material to be heated larger in size than the small size material to be heated that has been passed so far is passed. The heating temperature of the heated material portion corresponding to the pressed pressure nip portion is higher than that of the other heated material portions, causing uneven heating.

  In a film heating type image fixing device, when heat-resistant grease is interposed as a lubricant in order to reduce the sliding frictional resistance between the heating body and the film, the grease is caused by overheating of the non-sheet passing portion. Evaporation may cause defective film conveyance or the like, and may cause a reduction in film life.

  In addition, an elastic roller made of heat-resistant rubber or the like as a heating member causes a large difference between the outer diameter of the roller in the paper passing area and the outer diameter of the non-paper passing area due to a large coefficient of thermal expansion. However, there is a problem that an abnormal image such as a paper bag is generated when a large-sized material to be heated is passed with the difference in diameter.

  Furthermore, in the case of an apparatus in which the pressure elastic roller is a driving roller for conveying a heated material or a heat resistant film, the conveying speed of the heated material or the heat resistant film is determined by the peripheral speed of the driving roller. If the thermal expansion coefficient of the pressure elastic roller as the driving roller is large, the peripheral speed is likely to change. For example, in the case of an image heating fixing device of an image forming apparatus, the recording material is an image forming unit such as an image transfer unit. When straddling with the image heating and fixing device, the recording material is pulled by the image fixing device and the formed image is stretched or the image is blurred.

  As a countermeasure, there is a method in which a roller for controlling driving of paper feeding / conveying / paper discharging and a roller driving of the image forming unit are separately provided with a control motor, and the rotational speed is changed in accordance with a change in peripheral speed due to thermal expansion. However, there are problems such as an increase in the size of the apparatus and an increase in cost.

  As a solution to the prior art as described above, a proposal as described in Japanese Patent Application Laid-Open No. 7-5784 has been made, but there are the following problems even if this technique is used.

  That is, the heating material is made elastic, and an inelastic metal roller with high thermal conductivity is used for the pressure roller, so that the device that reduces the thermal expansion of the pressure roller supports the heated body with elasticity. For example, even when a heat-resistant rubber adhesive is used, there is a problem that the elastic heating body deteriorates due to repeated thermal shocks and the fixing portion is broken.

  In addition, when the support member and the elastic heating body are bonded and fixed, there is a problem that the two cannot be separated at the time of product disassembly and cannot be recycled.

  The present invention has been made in view of the above problems, and the intended process is to prevent misalignment due to thermal shock, and because it is easily disassembled, it can be recycled, and is not applied by applying tension to the planar heating element. An object of the present invention is to provide an image fixing apparatus capable of generating a pressure applied to a heating body.

  In order to achieve the above object, the present invention provides an image fixing apparatus using a sheet heating element configured by sandwiching a thin plate heater between heat resistant resin sheets, and winding an extension portion around a support member to which the sheet heating element is attached. It is fixed.

  According to the present invention, it is possible to fix the planar heating element without using an adhesive, so that it is possible to prevent displacement due to thermal shock, and it is easy to disassemble and can be recycled. .

  Further, it is possible to generate a pressure applied to the non-heated body by applying tension to the planar heating element.

  Furthermore, when a planar heating element with a low elastic modulus is used, it is difficult to adjust the pressure applied to the non-heated body, and a high-precision mounting dimension is required, but by adding an elastic member with a high elastic modulus Therefore, the adjustment of the pressing force can be facilitated and the dimensional accuracy can be relaxed.

  Further, by using a metal plate having a high conductivity for the elastic member, static electricity on the surface of the sheet heating element can be discharged to the ground.

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

<Embodiment 1>
The image fixing apparatus according to the present embodiment is a film heating type image fixing apparatus using a planar heating element, a heat-resistant film, and a high-rigidity pressure roller.

  1 is a perspective view of the entire image fixing apparatus, FIG. 2 is a detailed view of a heating portion, FIG. 3 is a cross-sectional view, and FIG. 4 is a diagram showing a configuration of a sheet heating element.

  In FIG. 4, 1 is a thin plate heater made of stainless steel, 2a and 2b are resin cover films to which the thin plate heater 1 is bonded and sandwiched, and the material is selected from polyimide. The sheet heater 1 and the cover films 2a and 2b constitute a side heating element 3.

  The thin plate heater 1 is U-shaped, and the end portions 1a and 1b are configured as conductive contacts. The planar heating element 3 can also be manufactured by performing an etching process on the resin film 2b on which stainless steel is deposited.

  2 and 3, the sheet heating element 3 is wound around the longitudinal direction of the support frame 4, and the sheet heating element 3 is urged by the protrusions 7 a and 7 b of the fixing member 7. A certain tension is applied.

  The support frame 4 and the fixing member 7 are made of heat-resistant resin, and nylon 6, nylon 66, polyethylene terephthalate, polybutylene terephthalate, polyphenylene in which about 30 to 40% of heat-resistant reinforcing fiber such as short glass fiber is mixed. It is desirable to use a heat-resistant reinforcing resin such as sulfide, a heat-resistant polymer such as silicon resin, fluororesin, polyimide, aromatic polyamide, polybenzimidazole, foamed glass, or the like.

  Reference numeral 8 denotes a seamless cylindrical slidable heat-resistant film, and 5 denotes a metal hollow pressure roller having high thermal conductivity such as aluminum or stainless steel. The sliding heat-resistant film 8 is circumferentially arranged so as to surround an assembly composed of the planar heating element 3, the support frame 4, and the fixing member 7, and constitutes one heating unit 9. The sheet heating element 3 forms a nip N along the arc of the pressure roller 5 via the slidable heat-resistant film 8 and is urged against the pressure roller 5 by an urging spring (not shown). .

  The sliding heat-resistant film 8 rotates around the planar heating element 3 as the pressure roller 5 rotates. The planar heating element 3 is positioned by a plurality of positioning pins 4 b on the support frame 4, and the thin plate heater 1 can be stably disposed at the approximate center of the nip N.

  In FIG. 3, the space 4a between the thin plate heater 1 and the support frame 4 is hollow, but it may be filled with a heat insulating material. In this case, since the heat from the thin plate heater 1 is difficult to escape, the thermal efficiency becomes higher.

  In FIG. 1, a through hole 4c is provided at the end of the support member 4, through which the terminals 1a and 1b of the thin plate heater 1 are exposed, and power from a recording apparatus main body (not shown) can be supplied to this portion.

  A gear 10 is fixed to the pressure roller 5 and rotates the pressure roller 5 by receiving power from a recording apparatus main body (not shown).

<Embodiment 2>
In FIG. 5, reference numeral 21 denotes a resin film fixing member, and a plurality of projections 21 a provided in the film fixing member 21 are joined to a plurality of holes 3 a provided in the exothermic heating element 3 and biased in the A direction. Then, it is fixed to the support member 4 by hooking on the 4d portion.

  The film fixing member 21 is made of a heat-resistant and elastically deformable resin material such as nylon 66. Therefore, when the film fixing member 21 is attached as shown in FIG. The planar heating element 3 is pulled in the direction of “and C, C”, and an appropriate urging force can be obtained with respect to the nip portion N.

  Further, by combining the sheet heating element 3 having a small elastic modulus and the film fixing member 21 having a large elastic modulus, the position of the thin plate heater 1 can be determined appropriately, and a sufficient urging force can be maintained. it can. Since the thin plate heater 1 is not fixed with a resin or adhesive which is weak against thermal shock, the durability is higher than that of a conventional adhesive fixing type heating device.

  Furthermore, since the heating unit 9 is easily disassembled, there is no shortage of conditions for recycling.

<Embodiment 3>
FIG. 7 shows an embodiment in which the film fixing member is constituted by a metal leaf spring.

  In the case of the electrophotographic recording method, since charges are accumulated in the heated object, static electricity accumulates on the surface of the sheet heating element, and eventually the charges are discharged, generating noise and causing abnormal control. is there. In order to avoid this, a grounding means for releasing the electric charge by contacting the surface of the planar heating element is required.

  The film fixing member 22 is a thin plate made of stainless steel, is fixed to the support member 4 while applying tension to the planar heating element 3, and charges accumulated on the surface of the planar heating element 3 are not shown in the frame of the recording main unit. Ground to ground.

  The present invention can be applied to any image fixing apparatus that heats a material to be heated at a pressure nip portion between a heating body and a pressure member.

1 is a perspective view of an image fixing device according to Embodiment 1 of the present invention. 1 is a partial cross-sectional view of an image fixing device according to Embodiment 1 of the present invention. 1 is a detailed cross-sectional view of an image fixing device according to Embodiment 1 of the present invention. 1 is an exploded view of a planar heating element of an image fixing device according to Embodiment 1 of the present invention. FIG. 6 is a perspective view of an image fixing device according to Embodiment 2 of the present invention. It is explanatory drawing of the image fixing apparatus which concerns on Embodiment 2 of this invention. FIG. 6 is a perspective view of an image fixing device according to Embodiment 3 of the present invention. It is sectional drawing of the conventional image fixing device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thin plate heater 2a, 2b Cover film 3 Planar heating element 4 Support member 5 Pressure roller 6 Sliding heat-resistant film 7 Fixing member 9 Heating unit 10 Drive gear 21, 22 Film fixing member

Claims (4)

In an image fixing device using a planar heating element configured by sandwiching a thin plate heater between heat resistant resin sheets,
An image fixing device, wherein an extension portion is wound around and fixed to a support member to which the planar heating element is attached.   The planar heating element is provided with a fixing member that fixes the extension portion while pulling, and when the planar heating element is attached to the heater support member, a fixed position is set so that a predetermined tension is generated in the planar heating element. The image fixing device according to claim 1, wherein the image fixing device is an image fixing device.   3. The image fixing device according to claim 2, wherein the planar heating element fixing member is made of an elastic body so that a predetermined tension is generated by supplementing an elastic force of the planar heating element having a low elastic modulus. .   3. The planar heating element fixing member is made of a conductive material, and is grounded to a frame ground of the main unit to discharge static electricity accumulated on the surface of the heat resistant resin sheet of the planar heating element. Image fixing device.

Images