JPH0572923A - Fixing device - Google Patents

Abstract

PURPOSE:To eliminate the need of a standby time, to eliminate such fear that fixing is insufficient and to provide a device whose power consumption is small as for the fixing device of a copying machine or the like. CONSTITUTION:A reflector 2 which reflects the heat of a heat source 1 is used also as the belt carrying guide of a fixing belt 3. The belt 3 is driven by a driving roller 4. At the aperture part of the reflector 2, a nip part 10 is formed by the belt 3 and a pressure roller 6 and the heat is concentrated to the nip part 10 by the reflector 2. At the nip part 10, a toner image 9 on a copying paper 8 is fixed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device, and more particularly to a fixing device for heating and fixing a toner image formed on a copy sheet.

[0002]

2. Description of the Related Art Conventionally, a heat roller fixing device having a pair of upper and lower rollers pressed against each other has been widely used.
In this heat roller fixing device, a heat source such as an infrared lamp is provided in at least one of the rollers. The heat roller fixing device conveys the copy paper on which the unfixed toner image is formed between both rollers to perform fixing.
Since this heat roller fixing device uses a roller having a large heat capacity, the entire roller is heated by the heat source provided inside, and a waiting time is required until the fixing temperature reaches a sufficient temperature.

In order to reduce the waiting time of the fixing device, JP-A-3-25473 proposes a fixing belt having a small heat capacity. This is a method in which a fixing belt having a small heat capacity is brought into contact with a solid heating element to heat the fixing belt to perform fixing.

[0004]

In the case of the fixing device disclosed in the above publication, the waiting time can be shortened as compared with the heat roller fixing device, but since the solid heating element and the fixing belt are in contact with each other, May wear out. When the solid heating element is worn, the performance as a heat source deteriorates. Moreover, since the fixing belt is heated by the solid heating element only at the nip portion, the fixing belt in a cold state is heated, and the temperature of the fixing belt is not sufficiently high, resulting in insufficient fixing of toner. Fear arises. Further, if the temperature of the solid heating element is increased in order to increase the fixing temperature, there arises a problem that power consumption must be increased.

[0005]

In order to solve the above problems, the present invention has a heat source and an opening which is provided so as to cover the heat source and concentrates the heat from the heat source in the opening. A reflecting member, a belt member that covers the opening of the reflecting member and is hung on the outer surface of the reflecting member, drive means for driving the belt member, and a side opposite to the opening of the reflecting member with respect to the belt member. It is characterized in that it is provided with a belt member and a pressing member forming a nip portion.

[0006]

The copying paper on which the unfixed toner image is formed is conveyed to the nip portion where the heat of the heat source is concentrated by the reflecting member. The belt member is heated in a short time by the heat concentrated in the nip portion, and the toner image on the copy sheet is fixed by the heat of the belt member. Further, the belt member is preheated on the outer surface of the reflecting member.

[0007]

EXAMPLE FIG. 1 shows the structure of a fixing device in this example. An endless fixing belt 3 is stretched around a reflection shade 2 provided so as to cover the halogen lamp 1 which is a heat source and a drive roller 4 provided on the side of the copy sheet 8 in the sheet discharge direction. The reflection shade 2 also functions as a belt conveyance guide on the side opposite to the drive roller 4. Further, the reflective shade 2 has an opening in a part thereof. A pressure roller 6 is provided on the side of the fixing belt 3 opposite to the opening of the reflection shade 2. Therefore,
At the opening of the reflection shade 2, the fixing belt 3 and the pressure roller 6 form a nip portion 10. A rush guide plate 7 is provided in front of the nip portion 10 so as to guide the copy sheet 8 to the nip portion 10.

The drive roller 4 is placed on the copy sheet 8 rather than the reflection shade 2.
Is provided on the side of the sheet discharge direction in order to make the distance from the contact of the fixing belt 3 to the reflection shade 2 to the nip portion 10 longer and to sufficiently perform the preheating of the fixing belt 3. Is.

The reflector 2 is a metal body such as Al whose inner surface is surface-treated with a material having a high reflectance such as Au, and has a shape for reflecting the heat of the halogen lamp 1 which is a heat source and concentrating the heat in the nip portion 10. With.

As shown in FIGS. 2 and 3, belt regulating plates 13 are provided at both ends of the reflection shade 2 in the longitudinal direction. The belt regulation plate 13 is provided so as to have a height equal to or larger than the thickness of the fixing belt 3. On the other hand, this fixing device is constructed so that the distances l1 and l2 at the longitudinal ends of the reflector 2 and the driving roller 4 shown in FIG. 4 do not match. As a result, the fixing belt 3 is biased to either one of the reflection shades 2 in the longitudinal direction, hits either one of the belt regulation plates 13 provided at both ends of the reflection shade 2, and is regulated at that position.

FIG. 5 is a view showing an inverted crown shape of the end portion 12 of the reflective shade 2. This inverted crown shape is formed in the end portion 12 of the reflection shade 2 in FIG. 1 over the longitudinal direction. As a result, the paper passing stability is improved and paper wrinkles are prevented. The position where this inverted crown shape is formed is the reflection shade 2
The end portion 12 may be provided not only on the copy paper supply side but also on both the supply and discharge sides of the copy paper. The amount L of the reverse crown is appropriately within 1 mm.

As shown in FIG. 6, the fixing belt 3 includes a metal belt 16 of Ni, SUS, Al or the like having a thickness of 100 μm (preferably 10 to 40 μm), and a fluororesin having a thickness of 30 μm or less on both surfaces. The layers 17 and 18 are coated. The fluororesin layer 17 on the inner surface of the fixing belt 3 improves abrasion resistance with the reflective shade 2 and the driving roller 4 and slidability with the reflective shade 2. On the other hand, the fluororesin layer 18 on the outer surface of the fixing belt 3 gives the fixing belt 3 releasability from the copying paper 8. Further, between the metal belt 16 and the fluororesin layer 17 on the side of the reflection shade 2, a black portion 14 in which the effective paper passage length W of the copy paper 8 is black-processed and a portion other than the effective paper passage length W is white-processed are white. And a section 15 are provided. As a result, the heat absorption rate of the fixing belt 3 can be improved. In addition, as shown in FIG. 7, a black paint and a white paint are mixed with fluororesin fine particles, which is coated on the surface of the metal belt 16 on the side of the reflection shade 2 to form a black portion 14a and a white portion 15a, respectively. By doing so, the same effect as the configuration of FIG. 6 can be obtained.

The fluororesin layer may be applied not only to the fixing belt 3 but also to the belt rubbing surface 11 of the reflection shade 2 with the fixing belt 3. However, since the fluororesin layer has thermal resistance, it is better to make it as thin as possible.

The driving roller 4 has a surface 5 made of silicon rubber and secures a frictional force with the fixing belt 3. Further, in FIG. 1, the drive roller 4 rotates clockwise to drive the fixing belt 3. As a result, the fixing belt 3 conveys the copy paper 8 in the paper discharge direction at the nip portion 10.

On the other hand, the pressure roller 6 rotates counterclockwise in FIG. 1 and conveys the copy paper 8 in the paper discharge direction. The pressure member is not limited to the roller, but may be a belt, a plate, or the like.

Next, the operation will be described. The copy sheet 8 on which the unfixed toner image 9 is formed is guided to the entry guide plate 7 and conveyed to the nip portion 10. The fixing belt 3 has a belt rubbing surface 11 of the reflection shade 2 before reaching the nip portion 10.
Is preheated at. Further, the reflection shade 2 concentrates the heat of the halogen lamp 1 in the nip portion 10 and heats the fixing belt 3 located in the nip portion 10. The toner image 9 on the copy paper 8 is fixed by the heated fixing belt 3.

In this embodiment, the fixing belt has an endless shape, but as shown in FIG.
The endless fixing belt 22 wound around 0 may be wound around the winding roller 21 via the reflection shade 2.

[0018]

As described above, according to the present invention, not only the belt is heated only at the nip portion, but also the belt member can be preheated by contacting the outer surface of the reflecting member, and the heat can be effectively utilized. It can be performed. As a result, the waiting time can be shortened, insufficient heating of the belt member can be prevented, and power consumption can be reduced.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a fixing device according to an embodiment of the present invention.

FIG. 2 is a side sectional view of a main part of this embodiment.

FIG. 3 is a front view of a main part of this embodiment.

FIG. 4 is a plan view of this embodiment.

FIG. 5 is a view showing an inverted crown shape of a reflective shade.

FIG. 6 is a sectional view showing the structure of a fixing belt.

FIG. 7 is a cross-sectional view showing another configuration of the fixing belt.

FIG. 8 is an overall configuration diagram of a fixing device according to another embodiment of the present invention.

[Explanation of symbols]

 1 Halogen lamp 2 Reflector 3 Fixing belt 4 Driving roller 6 Pressure roller 10 Nip part

Claims (1)

[Claims] 1. A heat source, and an opening provided so as to cover the heat source,
A reflecting member that concentrates heat from the heat source in the opening, a belt member that covers the opening of the reflecting member and is hung on an outer surface of the reflecting member, a driving unit that drives the belt member, and the belt member. The fixing device is characterized in that it has a belt member and a pressure member that forms a nip portion, the fixing device being provided on the side opposite to the opening of the reflection member.