JPH05204275A - Fixing roller supporting structure - Google Patents

Abstract

PURPOSE:To prevent the rotational load torque of an upper fixing roller from increasing by providing plural rotatable supporting rollers engaged in the groove part of the fixing roller on the upside of the fixing roller provided with the groove part in a circumferential direction on the surface of its end. CONSTITUTION:The supporting rollers 3 and 4 are engaged in the groove part 2 formed along a peripheral surface near both ends of the cylindrical upper fixing roller 1. The rollers 3 and 4 are arranged to be brought into contact with the oblique upside of the roller 1 so as to position the roller 1 lest the roller 1 should escape to the upside. A lower fixing roller 6 is pressed to the roller 1 side by a spring, and the upper and lower rollers 1, 6 are rotated when driving force is transmitted from a driving system. The rollers 3 and 4 are also rotated with the rotation of the rollers 1 and 6, and slip occurs between the respective shafts 3a and 4a of the rollers 3 and 4. Therefore, the rollers 3 and 4 are free to rotate, and when the roller 1 is rotated, the rollers 3 and 14 are smoothly rotated and the rotational load torque of the roller 1 is prevented from becoming large.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a supporting structure of a fixing roller formed by pressing an upper fixing roller and a lower fixing roller into contact with each other, and more particularly to an improvement of a supporting portion of the upper fixing roller.

[0002]

2. Description of the Related Art A fixing device that heats and presses a sheet on which toner is transferred to fix the toner on the sheet is usually
It has an upper fixing roller that houses a heater lamp therein, and a lower fixing roller that comes into pressure contact with the upper fixing roller. The upper fixing roller is formed in a cylindrical shape and has an open end for replacing the heater lamp. Therefore, as the bearing of the conventional upper fixing roller, a sliding bearing having the same inner diameter as the outer diameter is used, or both ends of the upper fixing roller are made slightly thinner than the central portion to insert the sliding bearing. FIG. 7 is a diagram showing a configuration of a conventional fixing device, which is a cylindrical upper fixing roller 10.
1. The lower fixing roller 104 is configured to be pressed upward by a sliding bearing 102 that supports the upper fixing roller 101 at both ends and an urging member 103 such as a spring so as to be in pressure contact with the upper fixing roller 101.

[0003]

When the sliding bearing 102 is directly inserted into the peripheral surface of the upper fixing roller 101 to pivotally support the upper fixing roller 101 as in the prior art, the inner diameter of the bearing is large and the friction resistance of the bearing surface is large. However, there is a problem in that the load torque of rotation becomes large due to the increase of Further, the contact area between the upper fixing roller 101 and the slide bearing 102 becomes large,
There is a problem that the amount of heat emitted from the upper fixing roller 101 increases and the temperature gradient (decrease) increases at both ends of the upper fixing roller 101.

An object of the present invention is to provide a fixing roller support structure capable of reducing the load torque of the rotation of the upper fixing roller and the temperature drop at both ends of the upper fixing roller.

[0005]

A fixing roller supporting structure according to a first aspect of the present invention includes an upper fixing roller having a heater lamp housed therein, and a lower roller which is urged toward the upper fixing roller to be pressed against the upper fixing roller. A fixing roller supporting structure including a fixing roller, wherein the upper fixing roller has a circumferential groove portion on an end surface, and is arranged above the upper fixing roller.
A plurality of support rollers that are engaged with the groove and are rotatable are provided.

According to a second aspect of the present invention, there is provided a support structure for a fixing roller, which includes an upper fixing roller having a heater lamp housed therein, and a lower fixing roller which is urged toward the upper fixing roller and brought into pressure contact with the upper fixing roller. In the supporting structure of the fixing roller, the upper fixing roller has a groove in the circumferential direction on the end surface, is arranged at the uppermost part of the upper fixing roller, is engaged with the groove, and is rotatable. It is characterized in that one supporting roller supported and a sliding member for supporting the upper fixing roller on the side surface are provided.

[0007]

In the fixing roller supporting structure according to the first aspect, the upper fixing roller is positioned by the supporting roller. A plurality of support rollers provided above the upper fixing roller are positioned so as to contact the upper fixing roller at multiple points and prevent the upper fixing roller from moving upward. In this state, the upper fixing roller is pushed up by the lower fixing roller, and the upper and lower fixing rollers are in pressure contact with each other. The support roller is engaged with a groove portion provided in the circumferential direction of the upper fixing roller, so that the upper fixing roller does not shift in the axial direction. The support roller is in contact with only a part of the upper fixing roller, and has a small contact area with the upper fixing roller. Therefore, the supporting roller does not significantly hinder the rotation of the upper fixing roller, and the amount of heat released from the upper fixing roller to the supporting roller is reduced.

In the fixing roller supporting structure according to the second aspect of the present invention, by disposing the supporting roller, the upper fixing roller is positioned at a fixed position even if a pushing force is applied by the lower fixing roller. Since the support roller is rotatable,
Even if a pushing force is applied by the lower fixing roller, the upper fixing roller does not lock the rotation and is rotated smoothly. Further, the sliding member laterally supports the upper fixing roller, and even if the installation position of the supporting roller is displaced from the uppermost portion, the upper fixing roller does not laterally escape.

[0009]

1 to 3 are views showing an embodiment according to claim 1, FIG. 1 is a view showing a side structure of a fixing roller supporting structure, and FIG. FIG. 3 is a perspective view, and FIG. 3 is a view showing a cross-sectional structure of a support roller that supports the upper fixing roller.

The upper fixing roller 1 is formed in a cylindrical shape, and grooves 2 are formed near both ends along the peripheral surface. Two support rollers 3 and 4 are engaged in this groove. As shown in FIG. 1, the support rollers 3 and 4 are disposed so as to contact obliquely above the upper fixing roller 1, and are positioned so that the upper fixing roller 1 does not escape upward. Further, the support rollers 3 and 4 are engaged with the groove portion 3 so that the upper fixing roller 1
Is positioned so that is not displaced in the thrust direction. The support rollers 3 and 4 are supported by the frame 5.

The lower fixing roller 6 is urged toward the upper fixing roller 1 by an urging mechanism including a spring 7. The upper fixing roller 1 is pressed against the supporting rollers 3 and 4 by this urging force, and the lower fixing roller 6 is caused by the reaction of the supporting rollers 3 and 4.
Is in pressure contact with. Driving force is transmitted to the lower fixing roller 6 from a drive system (not shown), and the upper and lower fixing rollers 1 and 6 rotate. This rotation also rotates the support rollers 3 and 4. The support roller 3 slips between the support roller 4 and the shaft 3a,
Slips between the shaft 4a. As a result, the support rollers 3 and 4 are rotatable, and when the upper fixing roller 1 rotates, the support rollers 3 and 4 rotate smoothly and the rotational load torque of the upper fixing roller 1 does not increase. FIG. 3 shows a cross-sectional shape of the support roller 3 (or 4). The support roller 3 is formed in a donut shape, and an edge portion is rounded.

The load torque of the apparatus of this embodiment is compared with the load torque of the conventional apparatus. In the case of the conventional apparatus shown in FIG. 7, the rotational load torque of the upper fixing roller 101 (one side of the roller) is expressed by the following equation: T = μ × F × D / 2 (1) On the other hand, those of the embodiment of the invention shown in FIG. _{1, T 1 = 2 × (} μ 1 × F / 2 × d 1/2) × 1 / D 1/2 × D / 2 = μ 1 × F × D / 2 × d ₁ / D ₁ (2) where D: roller diameter, μ: coefficient of friction between upper fixing roller and bearing or support roller, F: load, D ₁ : support rollers 3, 4 Outer diameter, d ₁ : inner diameter of the support rollers 3, 4, μ ₁ : friction coefficient between the support rollers 3, 4 and the shafts 3a, 4a,
Is.

If, for example, the upper fixing roller 1, the supporting rollers 3 and 4, and the shafts 3a and 4a are made of the same material, then μ = μ ₁ and T ₁ = T × d / D ₁ ... ( 3) is a formula. Since d ₁ / D ₁ <1, the following equation is obtained: T ₁ <T (4), which is in comparison with the load torque of the device shown in FIG. 7 of the embodiment of the present invention shown in FIG. It can be seen that the load torque is reduced more.

As a concrete numerical example, F = 3 kg μ = μ ₁ = 0.3 (μ is about 0.2 to 0.3) D = 20 mm is set, and in the case of the conventional device, T = 0.3 × 3 × 20/2 × 1/10 × 2 = 1.8 kg cm In the case of the device of this embodiment, T ₁ = 0.3 × 3 × 20/20 × 3 / 10.9 × 2 = 0.495 kg cm.

According to the apparatus of this embodiment, the temperature distribution of the upper fixing roller is also improved. FIG. 4 is a diagram showing the temperature distribution in the axial direction of the upper fixing roller shown in FIG. 1, and FIG. 6 is a diagram showing the temperature distribution in the axial direction of the upper fixing roller of the conventional apparatus. As can be seen from the figure, the upper fixing roller according to the embodiment of the present invention has less temperature drop at both ends and an improved temperature distribution in the axial direction as compared with the conventional apparatus.

FIG. 5 is a view showing a side structure of a fixing roller showing an embodiment according to claim 2. A supporting roller 11 is provided above the upper fixing roller 1, and the sliding member 1 is provided on both side surfaces.
2 and 13 are provided. The upper support roller 11 is made of a material that can withstand the urging force of the lower fixing roller 6, but the sliding members 12 and 13 do not need to have the same rigidity as the supporting roller 11, and have a friction coefficient with the upper fixing roller 1 as much as possible. Smaller materials can be selected. With this configuration, it is possible to prevent the load torque of the rotation of the upper fixing roller 1 from increasing. Further, since the contact area between the upper fixing roller 1, the supporting roller 11 and the sliding members 12 and 13 is small, it is possible to prevent the temperatures of both ends of the upper fixing roller from being significantly lowered. The support roller 11 and the sliding members 12 and 13 are engaged with the groove portion provided on the peripheral surface of the upper fixing roller 1, so that the upper fixing roller 1 is not displaced in the axial direction.

[0017]

According to the fixing roller support structure of the first aspect, the upper fixing roller is positioned by the plurality of supporting rollers and the lower fixing roller, and the contact area between the upper fixing roller and the supporting roller is small. The rotation of the upper fixing roller becomes smooth, and it is possible to prevent an increase in load torque and prevent the temperature of the supporting portion of the upper fixing roller from remarkably decreasing. Since the support roller is rotatable and can be rotated along with the rotation of the upper fixing roller, it is possible to prevent the load torque of the upper fixing roller from increasing.

According to the fixing roller support structure of claim 2,
The upper fixing roller is positioned by the supporting roller and the lower fixing roller, and the upper fixing roller has a small contact area with the supporting roller and the lower sliding roller, so that the load torque can be reduced and the escape of heat can be suppressed. ..

[Brief description of drawings]

FIG. 1 is a side view of a fixing roller showing an embodiment according to claim 1;

FIG. 2 is a perspective view showing the vicinity of an end portion of an identification transfer roller.

FIG. 3 is a diagram showing a sectional configuration of a support roller.

FIG. 4 is a diagram showing an axial temperature distribution of an upper fixing roller.

FIG. 5 is a side view of a fixing roller showing an embodiment according to claim 2;

FIG. 6 is a diagram showing a temperature distribution in the axial direction of a conventional upper fixing roller.

FIG. 7 is a diagram showing a side structure of a conventional fixing roller.

[Explanation of symbols]

 1 Upper Fixing Roller 2 Grooves 3, 4, 11 Supporting Rollers 3a, 3b Shaft 5 Frame 6 Lower Fixing Roller 7 Spring 12, 13 Sliding Material

Claims (2)

[Claims] 1. A support structure for a fixing roller, comprising: an upper fixing roller having a heater lamp housed therein; and a lower fixing roller urged toward the upper fixing roller and pressed against the upper fixing roller. The roller has a groove in the circumferential direction on the end surface,
Further, there is provided a fixing roller support structure which is disposed above the upper fixing roller and is provided with a plurality of rotatable support rollers which are engaged with the groove portion and are rotatable. 2. A fixing roller supporting structure comprising: an upper fixing roller having a heater lamp housed therein; and a lower fixing roller urged toward the upper fixing roller and brought into pressure contact with the upper fixing roller. The roller has a groove in the circumferential direction on the end surface,
Further, there is provided one support roller which is disposed on the uppermost part of the upper fixing roller, is engaged with the groove portion, and is rotatably supported, and a sliding member for supporting the upper fixing roller on a side surface portion. A fixing roller support structure characterized in that