JPH06337609A - Fixing device - Google Patents

Abstract

PURPOSE:To provide a fixing device which is suppressed in heat radiation at the ends of a fixing roller as far as possible and is miniaturized. CONSTITUTION:This fixing device is constituted to fix an unfixed toner image by pinching and transporting a recording material having this image to the pressure contact part of a pair of rollers rotating in pressurized contact with each other. The fixing device described above has a bearing structure formed by providing the outside surfaces near the axial ends of the fixing roller 1 with peripheral grooves 1a, disposing plural pieces of rolling members 7 within these peripheral grooves 1a and further, providing the outer side thereof with ring members 6 freely rollably supporting the rolling members 7.

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 a print recording device such as electrophotography and electrostatic recording, and more particularly to a fixing device for fixing toner onto a recording material at a pressure contact portion of a pair of rollers.

[0002]

2. Description of the Related Art FIG. 4 is a diagram for explaining a conventional fixing device.

Conventionally, a fixing device of this type has a fixing roller 1
And a pressure contact roller 2 facing and abutting the fixing roller 1. A halogen lamp 15 as a heat source is usually disposed inside the fixing roller 1 to heat the fixing roller 1.

The pressure roller 2 is pressed against the fixing roller 1 heated by the halogen lamp 15 at a constant pressure via the bearing 4 by the urging force of the spring 3, and the fixing roller 1 and the pressure roller 2 record. The entire surface of the material is conveyed while being pinched with a uniform pressure over the entire axial direction.

Further, even when the fixing roller 1 is under the pressure of the pressure contact roller, the fixing roller is supported by a ball bearing 5 at its end in order to rotate the fixing roller smoothly.

[0006]

However, the heat energy from the halogen lamp as the heater is transmitted not only to the fixing region of the fixing roller but also to the end portion of the fixing roller, and the heat energy is radiated into the atmosphere from the end portion. This causes a temperature drop at the end of the fixing roller and wastes energy.

Further, the ball bearings are expensive, and there has been a long-awaited demand to replace them with low-cost ball bearings.

Further, despite the high demand for downsizing of the device, the outer diameter of the ball bearing is relatively large.
This has been an obstacle to the miniaturization of the device.

SUMMARY OF THE INVENTION The present invention solves the above problems of the conventional device, and provides a fixing device having a bearing that can prevent the transfer of heat energy to the end portion of the fixing roller as much as possible and can reduce the outer diameter. With the goal.

[0010]

According to the present invention, the above object is to fix an image by nip-conveying a recording material having an unfixed toner image to a pressure contact portion of a pair of rollers which rotate in pressure contact with each other. In the fixing device, a peripheral groove is provided on the outer surface of the fixing roller in the vicinity of the end in the axial direction, a plurality of rolling members are arranged in the peripheral groove, and the rolling member is rotatably supported outside thereof. This is achieved by having a bearing structure provided with a ring member for

[0011]

In the present invention having such a structure, a peripheral groove for accommodating the rolling member of the bearing is formed in the vicinity of the end portion of the fixing roller, and the sectional area of the fixing roller is defined by the peripheral groove. It is smaller at the circumferential groove position. On the other hand, the heat from the heat source inside the fixing roller is transmitted by the fixing roller and reaches the end portion of the fixing roller. This heat transfer coefficient is proportional to the cross section of the fixing roller. Therefore, it becomes difficult for heat to be transferred from the circumferential groove position where the cross-sectional area is small toward the fixing roller end portion, and accordingly, heat dissipation at the roller end portion is prevented.

Further, since the roller is housed in the circumferential groove, the circumferential groove portion functions as an inner raceway for the rolling member of the bearing, so that the bearing inner ring becomes unnecessary and the outer diameter of the entire bearing becomes small. .

[0013]

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

<First Embodiment> FIG. 1 is a sectional view showing a roller end portion and its vicinity of a fixing device according to a first embodiment of the present invention.

In the figure, the pressure contact roller 2 is supported by a bearing 4 having a self-aligning property so as to be movable in the axial direction of the fixing roller 1. The pressure contact roller 2 is biased by the pressure spring 3 toward the fixing roller 1 via the bearing 4, and forms a pressure contact portion for fixing with the fixing roller 1.

The fixing roller 1 is provided with a peripheral groove 1a which is a raceway surface of a rolling member of a bearing in the vicinity of its end, and a plurality of rolling members, in the illustrated example, a spherical member 7 are formed in the peripheral groove 1a. Is arranged, and the ring member 6 as a bearing outer ring is arranged on the outer side thereof.
Is provided. The ring member 6 is positioned and supported by the side plate 8 of the device. Thus, the fixing roller 1 has the spherical member 7 and the ring member 6 in the circumferential groove 1a.
It is supported by the side plate 8 in a rotatable state via the. Therefore, the pressing force transmitted from the pressure spring 3 to the fixing roller 1 is finally received by the ring member 6 attached to the side plate 8 via the spherical member 7.

A halogen lamp 15 as a heat source is built in the fixing roller 1, and the power source of the apparatus is turned on.
When set to N, the halogen lamp 15 heats the fixing roller 1, and the heating energy is transmitted to the entire fixing roller. The thermal energy transferred to the end of the fixing roller is
In the conventional apparatus, the radiation is emitted to the outside (atmosphere) as shown by the arrow in FIG. 4, but in this embodiment, the peripheral groove 1a is formed near the end of the fixing roller 1 as shown in FIG. The roller cross-sectional area at the position of the circumferential groove 1a is small, and the heat energy transferred to the roller end portion is small. Therefore, as shown by the arrow in FIG. 1, heat radiation from the end of the fixing roller 1 to the outside is reduced.

Next, as apparent from FIG. 1, in this embodiment, the fixing roller 1 has the circumferential groove 1a as a raceway surface for the ball member 7 which is a rolling member, so that the conventional bearing is adopted. There is no need for the inner ring of the bearing as in the case of. Therefore, the outer diameter of the ring member 6 serving as the outer ring can be reduced to that extent, and the entire bearing is miniaturized.

Thus, the fixing roller 1 having started the fixing operation.
When is rotated by receiving a driving force from a drive transmission portion (not shown), the spherical member 7 rolls smoothly in the space between the ring member 6 and the circumferential groove 1a, and the fixing roller 1 is fixed to the ring member 6. In contrast, it rotates smoothly. That is, even in the state of receiving the pressure from the pressure contact roller 2, the rotation resistance of the fixing roller 1 with respect to the ring member 6 is small and the fixing roller 1 can smoothly rotate.

In this state, the recording material having the unfixed toner image is conveyed while being pinched between the rotating fixing roller 1 and the pressing roller 2, so that the toner image is transferred to the recording material. It is fixed.

<Second Embodiment> FIG. 2 shows a second embodiment of the present invention.

In the previous embodiment, the fixing roller 1 was fixed to the fixing roller 1 by means of the pressure roller 2 which rotates in pressure contact with the fixing roller 1. However, in the present embodiment, instead of the pressure roller, pressure is applied to guide the running of the heat resistant film. The feature is that it uses a frame.

The non-rotating pressure frame 9 is biased by the pressure spring 3 toward the axis of the fixing roller 1. An endless tubular heat-resistant film 10 is wound around the outer surface of the pressure frame 9, and the heat-resistant film 10 is sandwiched between the fixing roller 1 and the pressure frame 9 by the pressure of the pressure spring 3. ing.

As in the case of the previous embodiment, the fixing roller 1 is provided with peripheral grooves 1a near both ends in the axial direction, and a plurality of spherical members 7 arranged in the peripheral grooves 1a are held by a ring member 6. is doing. Therefore, as in the case of the previous embodiment, even if the fixing roller 1 is pressed by the pressing frame 9, the spherical member 7 is smoothly moved in the space between the ring member 6 and the circumferential groove 1a. By rolling, the rotation resistance of the fixing roller 1 becomes small, and the fixing roller 1 can smoothly rotate. When the fixing roller 1 rotates, the heat-resistant film 10
Only the frictional force with the fixing roller 1 causes the pressure frame 9 to rotate and run along the outer peripheral surface thereof.

A ceramic heater 11 is incorporated in the pressure frame 9 on the surface facing the fixing roller 1. Then, the heat of the ceramic heater 11 is transferred via the heat resistant film 10 to the recording material conveyed under pressure between the fixing roller 1 and the heat resistant film 10 to melt the toner of the unfixed toner image on the recording material. It is fixed as a permanent image on the recording material.

In the fixing step, the heating energy of the ceramic heater 11 is transmitted to the entire fixing roller 1. However, also in this embodiment, since the peripheral groove 1a is formed in the vicinity of the end portion of the fixing roller 1 and the cross-sectional area of the fixing roller 1 is small at the position of the peripheral groove 1a, the end portion of the fixing roller 1 is formed. The heat energy transferred to the fixing roller 1 is small, and therefore the heat radiation from the end of the fixing roller 1 to the outside is small. In addition, the outer diameter of the entire bearing becomes smaller as in the case of the previous embodiment.

Third Embodiment The heat radiation to the outside, which has been discussed in the above-mentioned two embodiments, is not only from the end portion of the fixing roller 1, but also from the bearing portion of the fixing roller 1. The third embodiment shown in FIG. 3 is a material having a heat insulating effect,
This point is improved by using a spherical member 20 and a ring member 21 formed of ceramic, for example. As a result, the heat radiation from the bearing portion of the fixing roller 1 is reduced, and the waste of heat energy can be further eliminated.

[0028]

As described above, according to the present invention, a circumferential groove is formed in the vicinity of the end portion of the fixing roller, the rolling member of the bearing is arranged therein, and the bearing is constituted in cooperation with the ring member for holding the rolling member. Therefore, it is possible to reduce the cross-sectional area of the fixing roller in the peripheral groove portion to reduce the heat transfer to the shaft end side portion of the peripheral groove portion, and the heat energy conventionally emitted from the roller end portion can be reduced. It is possible to reduce the amount of waste, to reduce the waste of energy, and to maintain the uniform temperature of the entire fixing roller, thereby eliminating uneven fixing.

Further, since it is not necessary to use an expensive conventional rolling bearing, the cost of the device can be reduced.

Further, regarding the mounting of the fixing roller, since it is sufficient for the bearing to have a mounting range which is slightly larger than the diameter of the fixing roller, it is convenient to make the fixing device more compact than the case where the conventional rolling bearing is used. Is.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a fixing device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of an essential part of a fixing device according to a second embodiment of the invention.

FIG. 3 is a cross-sectional view of a main part of a fixing device according to a third embodiment of the invention.

FIG. 4 is a cross-sectional view of a conventional device.

[Explanation of symbols]

 1 Fixing Roller 1a Circumferential Groove 6 Ring Member 7 Rolling Member (Spherical Member)

Claims (2)

[Claims] 1. A fixing device for fixing an image by conveying a recording material having an unfixed toner image between the pressure contact portions of a pair of rollers rotating in pressure contact with each other, in the vicinity of an axial end portion of the fixing roller. A bearing structure is provided in which a circumferential groove is provided, a plurality of rolling members are arranged in the circumferential groove, and a ring member that rotatably supports the rolling member is provided outside thereof. Fixing device. 2. The fixing device according to claim 1, wherein the fixing roller has a heating unit for melting and fixing the toner image.