JPH07219371A - Fixing device - Google Patents

Abstract

PURPOSE:To stabilize the contact pressure of a sliding contact point, to realize sure potential control and to prevent generation of odd sounds by forming an arbor of a press roller freely turnable around its central axis and disposing the sliding contact point nearer the central side in an axial direction than a ball bearing. CONSTITUTION:A heating roller 1 heated by a halogen heater 2 is mounted at a frame 4 via a bearing 3 and is driven by a gear 5. On the other hand, the press roller 6 in pressurized contact with this heating roller 1 is composed of the cylindrical arbor 6-a, elastic rubber roller 6-b and surface layer 6-c. The arbor 6-a is supported via the ball bearing 9 to a stationary shaft 7 fixed in a rotating direction as the central axis. Further, a pressurizing conducting plate 10 is mounted to the stationary shaft 7 on the side more inside than the ball bearing 9 and a contactor 10-a mounted at its front end is pressed to the arbor 6-a of the press roller 6 to form the sliding contact point. Concentricity is maintained at the arbor 6-a and the stationary shaft 7 by the ball bearing 9 and, therefore, the deflection of the arm part of the pressurizing conducting plate 10 is kept constant and the contact pressure at the sliding contact point by a contactor 10-a is stabilized as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device such as a copying machine or a printer for fixing an unfixed image such as a toner image to a recording material such as paper by a heating roller or a fixing film and a pressure roller, and particularly to a roller. Technology for controlling the core metal potential of

[0002]

2. Description of the Related Art In a fixing device used in an image forming apparatus such as a copying machine or a printer, a pressure roller having a heating roller heated by a heat source such as a halogen heater and an elastic layer serving as a surface layer in pressure contact with the heating roller is used. The so-called heat fixing method is a mainstream in which a roller constitutes a conveying means for a recording material such as paper, and both rollers fix an unfixed toner image on the recording material. In this heat fixing method, a technique for controlling the core metal potentials of the heating roller and the pressure roller has begun to be adopted for the purpose of improving fixing performance or safety.

As an example of such a conventional core metal potential control technique, FIG. 8 shows an example of controlling the core metal potential of a pressure roller. In FIG. 8, 1 is a heating roller and 6 is a pressure roller. The pressure roller 6 is provided with a fixed shaft 7 which is fixed in the rotational direction as a central shaft. The fixed shaft 7 uses an outer ring driven ball bearing 9 as a bearing member. The cored bar portion 6-a is supported by 9. A conduction ring 18 is sandwiched between thrusts of the core metal 6-a and the ball bearing 9, and the conduction ring 18 rotates together with the pressure roller 6. Conducting ring 1 that rotates in this way
On the fixed side with respect to 8, the contactor 19- of the conduction spring 19-
The sliding contact is provided by urging a, and the sliding contact is made with the rotation of the conduction ring 18 to come into contact with the sliding contact to establish conduction. Then, the contact 19-a is grounded through the diode 8 to control the potential of the core metal 6-a of the pressure roller to a predetermined potential.

As a method of controlling the core metal potential of the pressure roller, the example shown in FIG. 9 has been proposed. In this case, the pressure roller 6 has a shaft-shaped core metal portion 6-a, and is supported by the plain bearing 20 to rotate. Contact 19 of conduction spring 19
-A is outside the plain bearing 20 and is the core metal part 6 of the pressure roller.
It is in contact with -a, and is made conductive by this sliding contact. The place where the contactor 19-a is grounded via the diode 8 is similar to the above example.

[0005]

However, the conventional example described with reference to FIG. 8 has the following drawbacks.

(1) Since the conduction between the conduction ring 18 and the pressure roller 6 is due to the contact in the thrust direction, there is play in the thrust direction due to the structure, so the contact pressure is not stable. (2) Contact 19-a of the conduction ring 18 and the conduction spring 19
The contact is not stable for the same reason as above, and the sliding contact 19-a is greatly worn and the contact pressure varies widely, and the contact pressure fluctuates, so that a noise is likely to occur. (3) The conduction ring 18 and the pressure roller 6 together with the pressure spring 1
Since the position changes due to the force of 3, the contact point of the conduction spring 19 with the contact 19-a is not stable. (4) The sliding portion of the heating roller 1 with respect to the bearing 3 is a metal surface of aluminum, and the distance between this and the conduction ring 18 is structurally short, so that leakage easily occurs. In other words, it becomes a large constraint for the controllable core metal potential.

Further, in the conventional example described with reference to FIG.
Although the above-mentioned drawbacks are few, the contact pressure between the core metal 6-a of the pressure roller 6 and the contactor 19-a of the conduction spring 19 is
After all, there is a drawback that the pressure roller 6 is not stable because it moves.

Further, the above-mentioned conventional example is a fixing device using a heating roller, but it is disclosed in JP-A-63-3131.
82, JP-A-2-157878, and JP-A-4.
As disclosed in JP-A-44075 to 44083, a heat source is attached to one side of a heat-resistant film and a recording material is closely attached to the other side of the heat-resistant film, and the recording material is moved along with the film to transfer heat energy of the heat source to the film. There has also been proposed a fixing device of a type in which a recording material and a toner image on the recording material are provided via the recording material, and this fixing device also has the same drawbacks as described above with respect to the core metal potential control of the pressure roller.

In the above-mentioned conventional example, the potential of only the core metal of the pressure roller is controlled. However, there is also a conventional device that controls the potential of the core metal of the heating roller together with the pressure roller. There were similar drawbacks.

Therefore, the present invention solves the above problems,
It is an object of the present invention to provide a fixing device as described below.

First, according to the first invention of the present application, reliable potential control can be realized by stabilizing the contact pressure of the sliding contact, and no noise is generated at the contact. It is intended to provide a fixing device.

Next, in addition to the above object, the second invention of the present application improves stability of the contact pressure of the sliding contact, especially with respect to the movement of the roller in the thrust direction and the radial direction,
It is another object of the present invention to provide a fixing device capable of preventing a leak with a conductive member arranged outside the roller.

In addition to the object of the first and second aspects of the present invention, the third aspect of the present invention is to improve the stability of contact pressure against wear of sliding contacts. An object of the present invention is to provide a fixing device that can be used.

Further, in addition to the objects to be solved by the first to third inventions, a fourth invention according to the present application is also a contact pressure of a sliding contact in a system using a film and a roller. It is an object of the present invention to provide a fixing device capable of improving the stability of.

Further, a fifth invention according to the present application is, in addition to the object of the first to third inventions to be solved, also in a system using a heating roller and a pressure roller,
An object of the present invention is to provide a fixing device capable of improving the stability of the contact pressure of sliding contacts.

Further, in addition to the object of the fifth invention, the sixth invention according to the present application improves the stability of the sliding contact even when controlling the potential of the core metal of the heating roller. It is an object of the present invention to provide a fixing device that can be used.

[0017]

According to the first invention of the present application, the above object is to provide a recording material conveying means for rotating while contacting each other, and nipping and conveying a recording material carrying an unfixed image. A fixing device for fixing the unfixed image on the recording material, comprising a heat source disposed on at least one of the recording material conveying means, wherein at least one of the recording material conveying means has a central axis. And a cored bar supported on the central shaft and a surface layer formed on the cored bar, wherein the fixing device is provided with a sliding contact for electrically connecting the cored bar. The core of the roller body is supported on the central shaft via a bearing member and is rotatably arranged with respect to the central shaft, and the sliding contact is arranged in the axial direction more than the bearing member. It is achieved by being provided in the center side of.

According to the second invention of the present application,
The above object can be achieved in the first aspect of the present invention, in which the core metal of the roller body has a cylindrical shape and the sliding contact is provided on the inner peripheral surface side of the core metal.

Further, according to a third invention of the present application, in the above-mentioned first object, the core metal of the roller body is cylindrical, and the sliding contact is provided on the outer peripheral surface side of the central shaft. It is achieved by

According to the fourth invention of the present application,
The above-mentioned object is, in the above-mentioned first invention to the third invention, that the recording material conveying means is a film-shaped member in which one is a roller body and the other is endlessly movable, and the roller body is For the heat source arranged inside the film-shaped member,
This is achieved by arranging so as to press-contact via the film-shaped member.

Further, according to a fifth invention of the present application, in the above-mentioned first to third inventions, the above object is to provide a recording material conveying means, one of which is a heating roller having a heat source inside, The other is a pressure roller arranged so as to be in pressure contact with the heating roller, and a roller body provided with a sliding contact is used as the pressure roller.

According to the sixth invention of the present application,
In the first to third inventions, the object is to provide a recording material conveying means, one of which is a heating roller having a heat source inside, and the other of which is a pressure roller arranged so as to be in pressure contact with the heating roller. It is achieved by making both rollers a roller body provided with sliding contacts.

[0023]

According to the first aspect of the present invention, the core bar of the roller body is rotated about the central axis through the bearing member, so that a contact for providing a sliding contact is provided. Since the mounting area is secured in the gap between the cored bar and the central shaft, and the sliding contact is further provided on the central side in the axial direction than the bearing member,
Even if the central shaft or the core metal is displaced, the contact area of the sliding contact is secured as a surface, and the contact pressure is stabilized. as a result,
Reliable core metal potential control is performed and no noise is generated at the contacts.

According to the second invention of the present application,
Since the mandrel of the roller body has a cylindrical shape and the sliding contact is provided on the inner peripheral surface side of the mandrel, even if the central shaft or the mandrel is displaced in the thrust direction, the contact area of the sliding contact is the core. Secured on the inner peripheral surface of the gold cylinder, stable contact pressure can be obtained. Further, even if the central axis is displaced in the radial direction, the relative displacement of the core metal does not cause displacement of the sliding contact provided on the inner peripheral surface of the core metal, and stable contact pressure can be obtained. Further, the position of the sliding contact is secured a sufficient distance from the conductive member outside the roller body, so that no leak occurs.

According to the third invention of the present application,
Since the mandrel of the roller body has a cylindrical shape and the sliding contact is provided on the outer peripheral surface side of the central shaft, not only does the same function as in the second invention described above, but the outer peripheral surface of the central shaft is the inner peripheral surface of the mandrel. Since the diameter is smaller than the surface, the sliding speed decreases and wear resistance is improved.

Further, according to the fourth invention of the present application, even when one of the recording material conveying means is a film-shaped member arranged so as to be movable endlessly, the sliding contact is located at the above-mentioned position. In order to set, the roller body is arranged so as to come into pressure contact with the heat source arranged inside the film-shaped member through the film-shaped member in the conventional manner, and in the film-type fixing device, the sliding contact is provided. Realizes reliable core metal potential control by stabilizing the contact pressure of. Further, according to the fifth invention of the present application, even in the fixing device using the heating roller and the pressure roller, by providing the sliding contact at the above-mentioned position in the pressure roller, the heating roller can be used as in the conventional case. The pressure roller is brought into pressure contact to form a roller type fixing device, and reliable core metal potential control is realized by stabilizing the contact pressure of the sliding contact.

Further, according to the fifth invention of the present application, more reliable core metal potential control is realized by providing the sliding contacts on both the heating roller and the pressure roller.

[0028]

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

(First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS. 1 and 2 are sectional views showing an embodiment of the fixing device of the present invention.
As shown in FIGS. 1 and 2, this embodiment is an example in which the heating roller 1 and the pressure roller 6 are used as the recording material conveying means.
In the figure, a heating roller 1 heated by a halogen heater 2 as a heat source is attached to a frame 4 via a bearing 3. The heating roller 1 is driven by the gear 5. On the other hand, the pressure roller 6 pressed against the heating roller 1 is composed of a cylindrical core metal 6-a, an elastic rubber layer 6-b as a surface layer, and a surface layer 6-c. Here, the core metal 6-a of the pressure roller 6 is supported by a fixed shaft 7 fixed in the rotational direction as a central shaft via a ball bearing 9 as a bearing member. That is, the pressure roller 6 rotates as the outer ring of the ball bearing 9 rotates.

The fixed shaft 7 is made of an insulator 11 and a pressure plate 12.
It is pressed against the heating roller 1 side by being pressed by the pressing spring 13 while sandwiching.

Further, the pressure conducting plate 10 is attached to the fixed shaft 7 inside the ball bearing 9, and the pressure conducting plate 1 is also attached.
A contactor 10-a is attached to the tip of 0, and the contactor 10-a contacts the core metal 6-a of the pressure roller 6 to form a sliding contact.

Therefore, the core metal 6-a of the pressure roller 6 has the same potential as the fixed shaft 7 via the pressure conduction plate 10. Further, the fixed shaft 7 contacts with a leaf spring (not shown) and is grounded via a diode 8.

Details of mounting the pressure conducting plate 10 will be described with reference to FIG. FIG. 3 is a sectional view taken along the line AA of FIG. The arrows in the figure indicate the rotation directions of both rollers.
The pressure conducting plate 10 is positioned and fixed by the fixed shaft 7. The pressure conducting plate 10 is made of a leaf spring material, and the contact pressure is obtained by bending the arm portion 10-b.
Here, since the core metal 6-a of the pressure roller 6 and the fixed shaft 7 are kept concentric by the ball bearing 9, the arm portion 1 of the pressure conduction plate 10 is maintained.
The deflection of 0-b is also kept constant, and the contact pressure of the sliding contact by the contact 10-a is also stabilized. As a result, reliable core metal potential control is possible, and no noise is generated at the contact point. In addition, since the distance between the sliding contact and the heating roller 1 is sufficient, no leak will occur.

Next, details of the pressurization will be described with reference to FIG. FIG. 4 is a side view of the fixing device according to the present invention, but with a cover (not shown) removed. The fixed shaft 7 is fitted to the insulator 11 by D-cut at both ends, and the insulator 11 is fitted to the pressure plate 12. The pressure plate 12 is attached so as to be rotatable around the caulking shaft 21, and is biased counterclockwise by the force of the pressure spring 13. Further, here, the force of the pressure spring 13 is the elastic layer 6- of the pressure roller 6.
Needless to say, it is balanced by the repulsive force of b.

Next, details around the diode 8 will be described with reference to FIG. The arm portion 14-a of the leaf spring 14 bends and comes into contact with the fixed shaft 7 with an appropriate contact pressure. The leaf spring 14 is connected to the metal plate 22 via the diode 8, and the metal plate 22 is grounded to the frame 4 by the screw 23. Therefore, the core metal potential of the pressure roller 6 can be controlled by the characteristics of the diode.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

FIG. 6 is a drawing corresponding to FIG. 3 in the first embodiment. In the present embodiment, the static elimination brush 16 is used as a pressurizing conduction plate, the static elimination brush 16 is fixed to the fixed shaft 7 by the screw 17, and the brush portion 16-a which is the contactor of the static elimination brush 16 is pressed. Roller 6 core metal 6-a
To form a sliding contact and establish continuity. Needless to say, the material of the static elimination brush 16 is a conductive material such as stainless fiber or carbon fiber.

According to this embodiment, the contact pressure is reduced and the durability is improved. Other effects are similar to the above.

(Third Embodiment) Next, a third embodiment of the present invention.
Will be described with reference to FIG. The same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

FIG. 7 is a drawing corresponding to FIG. 3 in the first embodiment. In this embodiment, the pressure conducting plate 10 is attached to the core metal 6-a of the pressure roller 6, and its contactor 1
0-a forms a sliding contact by contacting the fixed shaft 7 to obtain conduction. In this embodiment, it takes more time to process the core metal 6-a of the pressure roller 6 than in the first embodiment, but the sliding speed of the contact 10-a decreases, so that the durability is excellent. Other effects are the same.

In the first embodiment, the core metal potential of the pressure roller 6 is controlled by using the diode 8. However, there are various control methods such as simply grounding or applying a bias. is there.

Further, in the above-mentioned embodiment, the case of controlling the potential of only the core metal of the pressure roller has been described, but the sliding contact is also provided to the heating roller by the same structure to control the potential of the core metal. You can also

Further, in the above-mentioned embodiment, an example using the heating roller has been described, but it is disclosed in JP-A-63-3131.
82, JP-A-2-157878, and JP-A-4.
As disclosed in JP-A-44075 to 44083, a heat source is attached to one side of a heat-resistant film and a recording material is closely attached to the other side of the heat-resistant film, and the recording material is moved along with the film to transfer the heat energy of the heat source to the film. Even in a fixing device of a type that applies a recording material and a toner image on the recording material via a pressure roller having a sliding contact as described above, a heat source disposed inside the film is used as a heat source. If it is arranged so as to come into pressure contact with a film, in a film type fixing device,
It is possible to perform reliable core metal potential control as described above.

[0044]

As described above, according to the present invention,
It has the following effects.

First, according to the first invention of the present application,
By rotating the cored bar of the roller body around the central axis via the bearing member, a mounting area for the contactor for providing the sliding contact is secured in the gap between the cored bar and the central axis, Further, since the sliding contact is provided on the central side in the axial direction with respect to the bearing member, the contact area of the sliding contact can be secured as a surface even if the central shaft or the core metal is displaced, and the contact pressure can be stabilized. You can As a result, it is possible to reliably control the core metal potential, and it is possible to prevent the occurrence of noise at the contacts. Further, since the sliding contact is arranged inside the bearing member which has conventionally been a dead space, it is possible to save space. Further, since the bearing member that supports the roller may be conductive or insulating, the degree of freedom in design can be improved.

Next, according to the second invention of the present application,
Since the cored bar of the roller body is cylindrical and the cored bar is rotated around the bearing member, the concentricity of the cored bar is easily ensured, and the sliding contact is provided on the inner peripheral surface side of the cored bar. Therefore, even if the central shaft or the cored bar is displaced, stable cored bar potential control is possible. Moreover, since the sliding contact has a highly rigid roller core metal, noise is unlikely to occur. Furthermore, the position of the sliding contact is
A sufficient distance is secured from the conductive member outside the roller body, and no leak occurs.

According to the third invention of the present application,
Since the mandrel of the roller body has a cylindrical shape and the sliding contact is provided on the outer peripheral surface side of the central shaft, not only the same effects as those of the second aspect of the present invention are obtained but also the outer peripheral surface of the central shaft is Since the diameter is smaller than that of the inner peripheral surface, the sliding speed is reduced and the wear resistance can be improved.

Further, according to the fourth invention of the present application, even when one of the recording material conveying means is a film-like member arranged so as to be movable endlessly, the sliding contact is located at the above-mentioned position. In order to set, the roller body can be arranged so as to come into pressure contact with the heat source arranged inside the film-shaped member through the film-shaped member as in the conventional case. It is possible to realize reliable core metal potential control by stabilizing the contact pressure of the sliding contacts.

According to the fifth invention of the present application,
Even in a fixing device using a heating roller and a pressure roller,
By providing the sliding contact at the above position in the pressure roller, the heating roller and the pressure roller can be pressed against each other as in the conventional case, and the core metal potential control is realized by stabilizing the contact pressure of the sliding contact. can do.

Further, according to the fifth invention of the present application, more reliable core metal potential control can be realized by providing the sliding contact on both the heating roller and the pressure roller.

[Brief description of drawings]

FIG. 1 is a detailed view of a sliding contact portion having a cross section taken along a line connecting the axes of a heating roller and a pressure roller, showing a fixing device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an overall view of the cross-sectional view of FIG.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a side view of the fixing device according to the first exemplary embodiment of the present invention, showing a state in which a cover is removed.

5 is a side view with the cover attached to FIG. 4, showing the diode attachment portion. FIG.

FIG. 6 is a view showing a second embodiment of the present invention and corresponds to FIG. 3 of the first embodiment.

FIG. 7 shows a third embodiment of the present invention and is a view corresponding to FIG. 3 of the first embodiment.

FIG. 8 is a sectional view corresponding to FIG. 1, showing an example of a conventional fixing device.

FIG. 9 is a sectional view corresponding to FIG. 1, showing an example of a conventional fixing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 heating roller (recording material conveyance means, roller body) 2 halogen heater (heat source) 6 pressure roller (recording material conveyance means, roller body) 6-a core metal 6-b elastic layer (surface layer) 6-c surface layer ( Surface layer) 7 Fixed shaft (center shaft) 9 Ball bearing (bearing member)

Claims (6)

[Claims] 1. A recording material conveying means for rotating while making contact with each other for nipping and conveying a recording material carrying an unfixed image, and a heat source arranged on at least one of the recording material conveying means. A fixing device for fixing an unfixed image on the recording material, wherein at least one of the recording material conveying means is formed on a central shaft, a cored bar supported on the central axis, and the cored bar. In a fixing device provided with a sliding contact for establishing conduction of the core metal, the core metal of the roller body is supported by the central shaft via a bearing member. The fixing device is rotatably arranged with respect to the central axis, and the sliding contact is provided closer to the center side in the axial direction than the bearing member. 2. The fixing device according to claim 1, wherein the core metal of the roller body has a cylindrical shape, and the sliding contact is provided on the inner peripheral surface side of the core metal. 3. The fixing device according to claim 1, wherein the core metal of the roller body has a cylindrical shape, and the sliding contact is provided on the outer peripheral surface side of the central shaft. 4. The recording material conveying means is a film-shaped member, one of which is a roller body and the other of which is endlessly movable. The roller body is arranged inside the film-shaped member. The fixing device according to any one of claims 1 to 3, wherein the fixing device is arranged so as to be in pressure contact with a heat source via the film-shaped member. 5. The recording material conveying means includes a heating roller, one of which has a heat source inside, and the other of which is a pressure roller arranged so as to come into pressure contact with the heating roller, and a roller body provided with a sliding contact. The fixing device according to any one of claims 1 to 3, wherein is the pressure roller. 6. The recording material conveying means is a heating roller, one of which has a heat source inside, and the other of which is a pressure roller arranged so as to come into pressure contact with the heating roller, and both rollers are provided with sliding contacts. The fixing device according to claim 1, wherein the fixing device is a fixed roller body.