JP2000352888A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely and speedily fix a toner image to paper in a fixing device. SOLUTION: In this fixing device where the toner image 38 that is transferred to a surface of the paper 32 is fixed to the surface of the paper 32, a 1st fixing device of a non contact method provided with a surface heater 33A heating the surface of the paper 32 without any contact and a 2nd fixing means of a contact method that is installed downstream in the carried direction of the paper 32 in relation to the 1st fixing device and consisting of a heat roller 31 provided with a heat radiating means and a press roller 34 with which pressure is applied to the paper 32 at a nip part with the heat roller 31 by being in a pressurized contact with the heat roller 31 are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for fixing a toner image transferred on a recording medium in an electrostatic recording type image forming apparatus such as a copying machine or a facsimile.

[0002]

2. Description of the Related Art An image forming apparatus such as a copying machine or a facsimile machine utilizing an electrophotographic process incorporates a fixing device for fixing unfixed toner transferred to the surface of a sheet (recording medium) in a transfer step. ing.

As a fixing method of a toner image in this fixing device, there are a solvent fixing method using a solvent, a pressure fixing method using a pressure roller, a contact heat fixing method using a heat roller, an infrared lamp and an oven. Conventionally, a non-contact heat fixing method using a toner is known.

However, the solvent fixing method produces an odor due to the emission of solvent vapor, which is not preferable in terms of environmental hygiene. Further, the pressure fixing method has poor fixability as compared with other fixing methods, and furthermore has a disadvantage in terms of economy because the pressure-sensitive toner is expensive. From such a background, generally, a heat fixing method using a heat roller, an infrared lamp, or the like is widely used.

In this heat fixing method, a fixed image is obtained by heating and melting the toner of the toner image transferred onto the surface of the sheet.

FIG. 4 shows a main part of a conventional fixing device by a heating method using a contact-type heat roller.

In FIG. 4, the fixing device is a combination of a heat roller 13A and a pressure roller 14 which rotate while being pressed against each other.

The heat roller 13A has a halogen lamp 11 as a heating source built in a cylindrical member 10 having excellent heat transfer characteristics. A plurality of surface layers 12 are formed on the outer peripheral surface of the cylindrical member 10. I have. On the other hand, the pressure roller 14
Is formed by forming a heat-resistant elastic layer on the outer peripheral surface of a cylindrical cored bar.

The paper 3 on which the unfixed toner image 38 is formed between the heat roller 13A and the pressure roller 14
2, the toner of the unfixed toner image 38 is heated and melted and pressed to be fixed on the paper 32.

Here, the surface layer 12 of the heat roller 13A is
Indicates that the sheet 32 after the fixing of the toner image 38 is
This is formed for the purpose of quickly separating the sheet 32 from the peripheral surface of A and separating the sheet 32. As the material of the surface layer 12, for example, a fluorine-based heat-resistant resin, silicone rubber, fluorine rubber, or the like is mainly used.

However, in the case of a full-color image forming apparatus, the four-color toner used has a low melting point and is very easily melted, so that a sufficient release property of the paper 32 is ensured on the surface layer 12 formed of heat-resistant rubber. Can not. For this reason, in the full-color image forming apparatus, as shown in the figure, an oil application mechanism 15 is provided, and for example, silicone oil is applied to the peripheral surface of the surface layer 12 as a release agent.

By applying such a release agent to the surface layer 12, the releasability of the sheet 32 from the surface layer 12 is greatly improved. Note that, in addition to the oil application mechanism 15, a cleaning mechanism 16 for removing residual toner and the like from the surface of the surface layer 12 is usually provided.

FIG. 5 is a schematic view showing a main part of a conventional fixing device having a non-contact type planar heater.

In the non-contact type fixing device, a heat source 18 using an infrared lamp or the like for heating the surface of a sheet 32 fed by a conveying roller 17 is disposed at a position away from the sheet 32, and the heat source 18 The unfixed toner on the surface of the paper 32 is heated and melted and fixed by heat.

As the heat source 18, a convection heating type planar heater, an infrared lamp for radiant heating, or the like is generally used.

[0016]

However, in the contact-type fixing device shown in FIG. 4, the surface layer 12 necessary for securing the separation property from the paper 32 must be formed on the heat roller 13A, It is very difficult to reduce the cost because expensive devices such as the mechanism 15 and the cleaning mechanism 16 are required.

On the other hand, in the non-contact type fixing device shown in FIG. 5, there is no member for pressing the sheet 32 in contact with the surface thereof. Since the warm-up time is short due to heat transfer, there are relatively few obstacles in terms of cost.

However, since the toner is fused only by the radiant heat or convective heat from the heat source 18 and there is no load of the pressing force, the toner image 38 is compared with the contact type fixing method.
Is inferior in fixing strength. For this reason, fixing to OHP paper becomes poor in light transmittance and smoothness, and lacks versatility.

Further, if the power supply to the heat source 18 is not properly controlled, the heat generation temperature becomes unstable, which is not preferable.

Further, since the heat is transmitted to the surface of the paper 32 via the air layer, if the ambient temperature around the paper 32 and the heat source 18 fluctuates greatly, the entire surface of the paper 32 has a uniform temperature distribution. It is very difficult to control the heating as described above, and it is easy to cause fixing failure.

Accordingly, an object of the present invention is to provide a fixing device capable of reliably fixing a toner image on a recording medium.

Another object of the present invention is to provide a fixing device that can quickly fix a toner image on a recording medium.

Another object of the present invention is to provide a fixing device which can fix a toner image on a recording medium at low cost.

[0024]

To solve this problem, a fixing device according to the present invention is a fixing device for fixing a toner image transferred onto the surface of a recording medium to the surface of the recording medium, the fixing device comprising: A non-contact type first fixing unit including a heating unit that heats the surface of the recording medium in a non-contact manner, a heat roller disposed downstream of the first fixing unit in the recording medium conveyance direction, and having a heat generating unit; A contact-type second fixing unit comprising a pressure roller which is pressed against the heat roller and presses the recording medium at a nip portion between the heat roller and the heat roller.

Thus, after the toner image is heated and melted by the first fixing unit, the heating and pressurization is performed by the second fixing unit, so that the toner image is reliably melted by the two heating operations and the second time. Since the welding is promoted at the time of heating, it is possible to reliably fix the toner image on the recording medium.

[0026] Further, by promoting the welding in the second heating and the second heating, it is possible to quickly fix the toner image on the recording medium.

According to another aspect of the present invention, there is provided a fixing device for fixing a toner image transferred on a surface of a recording medium to the surface of the recording medium, wherein the fixing device is heated by an induction heating member. Non-contact type first fixing means provided with a heating means for heating the surface of the recording medium in a non-contact manner;
A heat roller heated by an induction heating member and a pressure roller pressed against the heat roller to press the recording medium at a nip portion with the heat roller And a contact-type second fixing means.

Thus, since the first fixing means and the second fixing means are heated by the induction heating member which is a single heat source, the fixing for fixing the toner image on the recording medium at low cost. It becomes possible to obtain a device.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a fixing device for fixing a toner image transferred on a surface of a recording medium to the surface of the recording medium, wherein the surface of the recording medium is not contacted. A non-contact type first fixing unit provided with a heating unit for heating the recording medium, a heat roller disposed on the downstream side of the first fixing unit in the recording medium conveyance direction, and having a heat generating unit, and pressed against the heat roller. And a contact-type second fixing means comprising a pressure roller for pressing the recording medium at a nip portion with the heat roller, wherein the toner image is heated and melted by the first fixing means. After that, the heating and pressurization by the second fixing means is performed, and the toner image is reliably melted by the second heating and the fusion is promoted at the second heating, so that the toner image is surely formed on the recording medium. Can be established on It has the effect of becoming. Also,
The promotion of welding in the second heating and the second heating has an effect that the toner image can be quickly fixed on the recording medium.

According to a second aspect of the present invention, in the first aspect, the heating means is a fixing device which is a sheet heater or a halogen lamp, and reliably fixes the toner image on the recording medium. It has the effect that it becomes possible. Further, the toner image can be quickly fixed on the recording medium.

According to a third aspect of the present invention, in the first or the second aspect of the invention, the heat generating means includes an induction heating member disposed inside a hollow cylindrical heat roller,
This is a fixing device including a temperature-sensitive heating element disposed on the inner peripheral surface of the heat roller and heated by the induction heating member, and has an operation of reliably fixing the toner image on the recording medium. Further, the toner image can be quickly fixed on the recording medium.

According to a fourth aspect of the present invention, there is provided a fixing device for fixing a toner image transferred on a surface of a recording medium to the surface of the recording medium, wherein the fixing device is heated by an induction heating member and is fixed to the surface of the recording medium. Non-contact type first fixing means provided with a heating means for heating the recording medium in a non-contact manner, and a heat roller which is disposed downstream of the first fixing means in the recording medium conveyance direction and heated by the induction heating member And a contact-type second fixing unit including a pressure roller that is pressed against the heat roller and presses the recording medium at a nip portion with the heat roller. The first fixing unit includes a first fixing unit and a second fixing unit. Since the two fixing units are heated by the induction heating member, which is a single heat source, it has an effect that it is possible to obtain a fixing device for fixing the toner image on the recording medium at low cost.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. In these drawings, the same members are denoted by the same reference numerals, and duplicate description is omitted.

(Embodiment 1) FIG. 1 is a perspective view showing a fixing device according to Embodiment 1 of the present invention, and FIG. 2 is a schematic view showing a main part of the fixing device of FIG.

As shown in FIGS. 1 and 2, the fixing device according to the present embodiment includes a non-contact type first fixing unit along a conveying direction of a sheet (recording medium) 32 (in a direction indicated by an arrow in FIG. 1). And a contact-type second fixing means are arranged in order.

Here, the first non-contact fixing means includes a transport roller 30 for transporting the paper 32 and a sheet heater (heating means) as a heat source for heating the surface of the transported paper 32 in a non-contact manner. ) 33A.

The transport roller 30 is driven to rotate by a reduction mechanism (both not shown) constituted by a drive motor and a gear train. The sheet heater 33A is disposed at a distance of about 5 mm from the surface of the sheet 32 to be conveyed, and heats and fuses the unfixed toner image 38 on the surface of the sheet 32 by convection heating.

It should be noted that other heating means such as a halogen lamp can be used in place of the sheet heater 33A. When a halogen lamp is used, unfixed toner is fused by radiant heating.

The contact-type second fixing means includes a pair of side blocks 28 and 29 arranged on both sides in the conveying direction.
A heat roller 31 is mounted via bearings 20A and 20B, and a pressure roller 34 pressed against the heat roller 31. The rotation of the heat roller 31 and the pressure roller 34 is transmitted from a motor gear 21 attached to an output shaft of a motor (not shown) via two-stage gears 22 and 23 and a roller gear 19.

Then, as shown in FIG.
The fourth bearing 20B is supported by a pressure mechanism 27 including a compression spring 26 and is urged toward the heat roller 31 side.

The heat roller 31 includes a hollow cylindrical cored bar 31A having excellent heat transfer characteristics and a built-in heat generating means. The heat generating means is an IH heat coil 35 which is an induction heating member disposed substantially in the center of the cored bar 31A.
And a temperature-sensitive heating element 36, which is a metal member disposed on the inner peripheral surface of the cored bar 31A and heated by the IH heat coil 35. A surface layer 31B of a hard material is formed on the outer peripheral surface of the core metal 31A.

Then, self-temperature control at the Curie temperature acts between the IH heat coil 35 and the temperature-sensitive heating element 36, so that an appropriate fixing heating temperature is controlled.

On the other hand, the pressure roller 34 is a cylindrical core 3
The heat-resistant elastic layer 34B is formed on the outer peripheral surface of 4A. As described above, the pressing mechanism 27 urges the heat roller 31 toward the heat roller 31 to maintain the pressing force.

The fixing device is provided with a controller for simultaneously controlling the speed of the non-contact type driving motor of the first fixing means and the contact type driving motor of the second fixing means. Thus, the sheet 32 is conveyed from the sheet heater 33A to the heat roller 31 at a constant speed.

In the fixing device having the above configuration, the sheet 32 conveyed by the conveying roller 30 is heated by convection heating by the sheet heater 33A, and the unfixed toner on the surface of the sheet 32 is heated and melted and fused. .

Thereafter, the sheet 32 is nipped between the heat roller 31 and the pressure roller 34, and is heated again by the heat transfer from the IH heat coil 35 built in the heat roller 31 and simultaneously applied by the nip force. Pressed.

Therefore, the unfixed toner image 38 on the surface of the paper 32 is reliably melted by being heated twice before the fixing process is completed, and is pressed during the second heating to cause the welding. Promoted. As a result, the toner image 38 can be reliably and promptly fixed to the sheet 32.

As described above, a halogen lamp can be used as a heat source of the non-contact type first fixing means instead of the sheet heater 33A. When a halogen lamp is used, radiant heating using infrared rays is obtained, unlike convective heating by the planar heater 33A.

(Embodiment 2) FIG. 3 is a schematic view showing a main part of a fixing device according to Embodiment 2 of the present invention.

In the present embodiment, the IH heat coil (induction heating member) 35 is not disposed inside the heat roller 31 as shown in the first embodiment, but is disposed outside. .

In the present embodiment, the IH heat coil 35 for heating the heat roller 31 is disposed upstream of the heat roller 31 so that the IH heat coil 35
2, a pre-heating plate 37 is disposed as first fixing means heated by the IH heat coil 35.

By effectively operating the self-temperature control at the Curie temperature in combination with these combinations, an appropriate fixing heating temperature can be controlled and a quick fixing device can be obtained.

In the present embodiment, the IH heat coil 35 is disposed outside, and the IH heat coil 35 heats not only the pre-heating plate 37 but also the heat roller 31 constituting the second fixing means. Temperature controlled.

As a result, the number of heat sources can be reduced to one, and a low-power, low-cost and quick fixing device can be realized.

Further, by applying pressure in the fixing step, it is possible to satisfy conditions required for fixing, such as fixing strength and light transmittance and smoothness of OHP as a recording medium.

[0056]

As described above, according to the present invention, the toner image is heated and melted by the first fixing means and then heated and pressurized by the second fixing means. Since the image is reliably melted and the welding is promoted at the time of the second heating, an effective effect that the toner image can be surely fixed to the recording medium can be obtained.

Further, according to the present invention, an effective effect of being able to quickly fix a toner image on a recording medium can be obtained by promoting welding in the second heating and the second heating. .

The first fixing means and the second fixing means are controlled by an induction heating member.
When the first fixing means and the second fixing means are heated by the induction heating member which is a single heat source, the toner image is recorded at low cost. An advantageous effect is obtained that a fixing device for fixing to a medium can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a fixing device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a main part of the fixing device of FIG. 1;

FIG. 3 is a schematic diagram illustrating a main part of a fixing device according to a second embodiment of the present invention;

FIG. 4 is a schematic view showing a main part of a conventional fixing device by a heating method using a contact-type heat roller.

FIG. 5 is a schematic view showing a main part of a conventional fixing device having a non-contact type planar heater.

[Explanation of symbols]

 REFERENCE SIGNS LIST 31 heat roller 32 paper (recording medium) 33A planar heater (heating means) 34 pressure roller 35 IH heat coil (induction heating member) 36 temperature-sensitive heating element 37 preheating plate 38 toner image

Claims (4)

[Claims] 1. A fixing device for fixing a toner image transferred on a surface of a recording medium to the surface of the recording medium, comprising a heating means for heating the surface of the recording medium in a non-contact manner. A first fixing unit, a heat roller disposed downstream of the first fixing unit in the conveying direction of the recording medium and having a heating unit, and a nip portion that is in pressure contact with the heat roller and is in contact with the heat roller. And a contact-type second fixing unit including a pressure roller for pressing the recording medium. 2. A fixing device according to claim 1, wherein said heating means is a sheet heater or a halogen lamp. 3. The heat generating means includes: an induction heating member disposed inside the hollow cylindrical heat roller; and a thermosensitive heat generation member disposed on an inner peripheral surface of the heat roller and heated by the induction heating member. The fixing device according to claim 1, wherein the fixing device comprises a body. 4. A fixing device for fixing a toner image transferred onto a surface of a recording medium to the surface of the recording medium, wherein the heating means is heated by an induction heating member to heat the surface of the recording medium in a non-contact manner. A non-contact type first fixing unit including: a heat roller disposed downstream of the first fixing unit in the conveyance direction of the recording medium and heated by the induction heating member; A fixing device comprising: a contact-type second fixing unit including a pressure roller that is pressed and presses the recording medium at a nip portion between the heat roller and the heat roller.