JPH04323143A - Flat belt drive roller and flat belt drive device - Google Patents

Abstract

PURPOSE:To improve sliding characteristics of a flat pelt drive roller such as reduction in frictional resistance, stabilization of frictional coefficient, etc., according to variation in temperature, humidity, etc., in an electrophotographic device. CONSTITUTION:Multiple short fibers F, F,... are mixed into the surface portion of a roller 13 for driving a flat belt 11, oriented roughly in axial direction of the roller 13, and a part of it is exposed from the surface of the roller. The flat belt 11 is driven by a grip force of the exposed short fibers F, F,... to reduce a coefficient of friction and stabilize the frictional characteristics according to variation in temperature and humidity. The short fibers F, F... may be oriented so that they have a specified inclination relative to axial and circumferential directions. By providing a belt guide members 18, 18 on the roller and/or flat belt, specially accurate belt driving is enabled.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat belt, particularly a roller for driving a photoreceptor belt, transfer conveyor belt, etc. of an electrophotographic device.

0002

2. Description of the Related Art Conventionally, in an electrophotographic apparatus, for example, in order to make the apparatus lighter and more compact, a plurality of roller members arranged approximately parallel to each other have been used, the surfaces of which are coated with a photoreceptor layer or a dielectric layer. It is known to span the formed flat belt and use the flat belt as a photoconductor belt or a transfer conveyance belt instead of a photoconductor drum.

[0003] However, flat belts used for such purposes are often made of a material with low elongation and high strength, such as a plastic film or metal foil, as a base material. Therefore, since this type of flat belt is difficult to elastically deform, dimensional errors of each related parts, installation errors of roller members, etc.
Unbalanced belt tension, uneven belt circumference, etc. cannot be absorbed by deformation of the belt itself, and as a result, when the flat belt runs, a thrust force is applied that tries to shift the belt to one side, causing meandering. There was a problem in that it was easy for this to occur.

However, in such an electrophotographic apparatus, high precision and high resolution are required in order to form accurate images, so it is necessary to prevent meandering of the flat belt as much as possible.

[0005] As a conventional technique for preventing such belt meandering, Japanese Patent Application Laid-open No. 127501/1983
As shown in Japanese Patent Application Laid-Open No. 59-205052, a belt is provided with a guide to prevent meandering, and
As shown in Japanese Patent No. 7-60347, it has been proposed to forcibly prevent the flat belt from meandering by providing a regulating member. Furthermore, as shown in Japanese Utility Model Application Laid-open No. 58-110609 and Japanese Utility Model Application Publication No. 64-48457, there are systems in which meandering is corrected using a complicated mechanism structure.

[0006]

[Problems to be Solved by the Invention] However, the methods disclosed in Japanese Utility Model Application Publication No. 58-110609 and Japanese Utility Model Application Publication No. 64-48457 use a complicated mechanism to correct meandering, which is expensive and expensive. Not only does it require extra space and lead to an increase in the size of the entire device, but it also
Since the mechanism is complex and has a large number of parts, the number of failure-causing parts increases accordingly, and it is difficult to say that the reliability of the device is sufficiently ensured.

[0007] Furthermore, in the configurations shown in Japanese Patent Application Laid-open No. 56-127501 and Japanese Patent Application Laid-open No. 59-205052,
When providing a guide on a flat belt, it is necessary to provide the guide with high precision, and especially in the case of a seamless belt, it is extremely difficult to form the guide itself.

On the other hand, Japanese Patent Application Laid-open No. 57-60347,
This system attempts to prevent meandering with a relatively simple structure, but since the flat belt is forcibly received by an external member, when the thrust force accompanying the meandering of the flat belt becomes large, the end of the belt may Also, there is a risk that the regulating member may be damaged.

Furthermore, in each of the above publications, the belt
Because the rollers are in close contact with each other, especially when the rollers are made of metal, there are problems such as the flat belt being easily damaged if foreign matter gets between them, and the friction characteristics being affected by the interface. Since it is determined by the state, there is a problem that the sliding characteristics become unstable due to changes in temperature and humidity.

The present invention has been made in view of the above, and its object is to provide a means for reducing the thrust force generated during running of the flat belt on the side of the roller used in the flat belt drive device. By taking these measures, it is an object of the present invention to solve the above-mentioned problems and to provide a roller that precisely drives a flat belt with a simple structure.

On the other hand, another problem is that in a flat belt drive device, if the flat belt is subjected to a large lateral force, the flat belt itself may sit in the width direction, especially if the belt is thin, such as a photoreceptor belt in an electrophotographic device. There is a risk that the waving phenomenon may occur.

[0012] In order to prevent such a waving phenomenon, for example, a pair of helical grooves extending outward symmetrically with respect to the running direction of the belt with the central part of the metal roller as a boundary may be provided. It is conceivable to create tension in the belt in the width direction.

However, in this case, there is a problem that not only the belt is damaged by foreign objects as described above, but also the back side of the belt is greatly worn due to sliding with the corner portion of the groove end, and the life of the belt is shortened. be.

[0014] In view of this point, a second object of the present invention is to suppress the waving phenomenon of the belt by providing a means for generating tension in the width direction of the belt without causing damage to the back surface of the belt.

[0015]

[Means for Solving the Problems] In order to achieve the above object, the means taken by the present invention is that the surface portion of the roller member is made of an elastic body mixed with short fibers, and the short fibers are oriented in a specific direction. The purpose is to expose the material to the surface of the roller while moving it.

Specifically, the means taken by the invention of claim 1 is directed to a flat belt driving roller for winding and driving a flat belt. At least the surface portion is formed of an elastic material such as rubber mixed with a large number of short fibers, and the short fibers are oriented approximately in the axial direction of the roller, and a portion of the short fibers are oriented in the axial direction of the roller.
The structure is such that it is exposed from the surface of the la.

The means taken by the invention of claim 2 is directed to a flat belt driving roller for winding and driving a flat belt. Then, at least the surface portion is formed of an elastic body such as rubber mixed with a large number of short fibers, and the short fibers are oriented with a certain inclination in the axial direction of the roller and the circumferential direction of the roller, A portion of the roller is exposed from the surface of the roller.

The means taken by the invention according to claim 3 is that in the invention according to claim 2, the short fibers are oriented symmetrically with respect to the substantially central part in the axial direction of the roller. .

According to a fourth aspect of the present invention, in the first, second or third aspect of the present invention, the short fibers are made of aramid fibers.

The means taken by the invention of claim 5 is directed to a flat belt drive device in which a flat belt is wound around a plurality of rollers and driven.

[0021] At least one of the plurality of rollers is formed into a roller according to claim 1, 2 or 3 above.
It is composed of la.

The means taken by the invention of claim 6 is that in the invention of claim 5, a belt guide member for regulating the lateral movement of the flat belt is provided on the flat belt and/or the roller.

The means taken by the invention according to claim 7 is that in the invention according to claim 5 or 6, the flat belt is used as a photoreceptor belt or a transfer conveyance belt.

[0024]

[Operation] With the above configuration, in the invention of claim 1, the low
Since the short fibers are exposed on the surface of the roller, the short fibers are interposed between the belt and the roller, thereby avoiding close contact between the two. Therefore, even when foreign matter is mixed in, the belt is not damaged, the coefficient of friction between the two is reduced, the stability against changes in temperature and humidity is achieved, and the thrust force when the belt shifts to one side is reduced.

Moreover, since the short fibers are oriented approximately in the axial direction of the roller, they can be easily oriented by die extrusion processing of the hose material mixed with the short fibers, resulting in low manufacturing costs. .

[0026] In the invention of claim 2, each short fiber is oriented so as to have a constant inclination on average with respect to the roller axis and also to have a constant inclination in the circumferential direction. By extruding a short fiber-containing hose using a parallel part and a die tapered so that the diameter increases from the parallel part, the short fibers can be easily oriented, and the short fibers can be easily oriented in the direction in which the short fibers are inclined. Since the flat belt is driven, running resistance is further reduced.

In the third aspect of the invention, the short fibers exposed on the roller surface are oriented symmetrically with respect to the axial center of the roller, so that when the belt is driven, the short fibers are oriented symmetrically to each other with respect to the axial center of the roller. A tension force is generated that tends to displace the belt outward in the width direction, and the waving phenomenon of the belt is suppressed.

In the invention of claim 4, since the short fibers are made of aramid fibers, the high grip force due to the high rigidity of the aramid resin and the good sliding properties at high PV values, and the low thrust force are achieved. In addition, the high heat resistance of aramid fibers makes it easy to expose the short fibers by polishing the surface of the roller.

According to the fifth aspect of the present invention, in the flat belt drive device, the belt running characteristics are improved due to good sliding characteristics such as reduction and stabilization of the friction coefficient between the roller and the belt.

[0030] According to the invention of claim 6, since the thrust force when the flat belt is shifted to one side is reduced, the belt guide member provided on the flat belt and/or the rollers and the belt ends are not damaged. Meandering of the belt is prevented and precision drive is realized.

According to the seventh aspect of the invention, in an electrophotographic apparatus in which a photoreceptor belt or a transfer conveyance belt is used, environmental conditions such as temperature and humidity at the place of use change greatly, but even under such environments, Features such as a stable friction coefficient between the belt and rollers and low thrust force when the belt shifts to one side make it possible to precisely drive the flat belt and improve image forming characteristics.

[0032]

Embodiments (First Embodiment) First, a first embodiment of the present invention will be described based on FIGS. 1 and 2.

FIG. 2 schematically shows an electrophotographic apparatus A according to the present invention, in which reference numeral 10 denotes a three-axis photoreceptor belt drive device, and 20
30 is a paper feeding device that supplies paper to the transfer and conveyance belt device 20; and 40 is a fixing device that fixes toner on the transferred paper from the transfer and conveyance belt device 20. . That is, an image is formed on the photoconductor belt 11 (flat belt in the present invention) of the photoconductor belt drive device 10 by the lens system 50, and an image is formed on the paper fed from the paper feed device 30 by the transfer conveyance belt drive device 10. The image is transferred. Note that 60 is a developing device that supplies toner to the photoreceptor belt 11;
80 is a belt cleaning device.

In the photoreceptor belt device 10, 12
1 is a drive roller rotationally driven by a motor (not shown), and 13 and 14 are first and second driven rollers, respectively. Further, in the transfer conveyance belt device 20, 2
1 is a transfer conveyance belt, 22 is a drive roller, 23 is a driven roller, and each of the above-mentioned rollers 12 to 14 and 22, 23
is the flat belt driving roller according to the present invention.

The photoreceptor belt 11 has a photoreceptor formed on a base material, and the tensile modulus of the biaxially stretched polyester constituting the base material is set to 200 kg/mm 2 or more. However, the material of the tension body mentioned above may be metal thin plate such as nickel, stainless steel, PES, PEE, etc.
Plastic films such as K, aramid, and polyimide may also be used.

As shown in FIG. 1, the first driven roller 12 includes a stepped roll-shaped metal shaft member 16,
It consists of a cylindrical member 17 fitted into the large diameter portion of the shaft member 16 except for both ends. Then, the cylindrical member 1
Flange members 18, 18 made of metal or sliding plastic are provided at both ends of the photoreceptor belt 11 as belt guide members for regulating the lateral movement of the photoreceptor belt 11. The driving range of No. 11 is restricted within a predetermined range.

Here, the cylindrical member 17 is made of an elastic material such as rubber mixed with a large number of short fibers F, F, . . . made of aramid fibers, and each short fiber F, F, .
They are substantially oriented in the axial direction of the first driven roller 13 (x-axis direction in the figure), and a portion of the short fibers F, F, . . . are exposed on the roller surface.

Here, as shown in FIG. 3, the method for manufacturing the roller of the present invention involves short fibers F, F oriented approximately parallel to the plate surface.
,... is formed by rolling, and this elastic plate 19 is attached to the shaft member 1 of the first driven roller 13.
6 (see Figure 4), the short fibers F, F
,... are substantially oriented in the axial direction, and their surfaces are polished so that a portion of the short fibers F, F,... are exposed upward on the roller surface. In addition, by extruding a hose mixed with short fibers F, F, ... with a die having a predetermined parallel part, each short fiber F, F, ... is randomly distributed, but on average, After being substantially oriented in the axial direction, the cylindrical member 17
The surface may be mechanically ground.

Materials for the short fibers F include organic fibers such as PET, nylon, aramid, cotton, and cellulose;
Inorganic fibers such as carbon fibers, inorganic acicular fillers such as silicon carbide, iron oxide, titanic acid, etc. can be used, and the length thereof is preferably about 1 to 10 mm. Furthermore, the cylindrical member 17
The elastic body which is the matrix can be made of not only general rubber materials but also thermoplastic elastomers, etc., and the thickness of the elastic body is preferably 1 mm or more. Further, in this embodiment, the matrix of the cylindrical member 17 is EPDM.
The short fibers F, F, .

The second driven roller 14 has the same structure as the first driven roller 13, and furthermore, the second driven roller 14 has the same structure as the first driven roller 13, and the drive roller 22 and the driven roller in the transfer conveyance belt device 20 are similar to each other. The same configuration can be applied to the roller 23 as well.

Therefore, in the first embodiment, the cylindrical member 17 of the first driven roller 13 has a large number of short fibers F, F,...
Furthermore, since some of the short fibers F, F, ... are exposed from the surface of the cylindrical member 17, the surface in contact with the photoreceptor belt 11 is no longer a smooth surface. , close contact between the photoreceptor belt 11 and the first driven roller 13 is avoided. In other words, when the belt and rollers are in close contact with each other, foreign matter such as toner and paper dust may enter between the belt and rollers in the electrophotographic process as in the above embodiment.
Although there is a risk of scratches reaching the back or front surface of the photoreceptor belt 11, the interposition of the short fibers F, F, ... prevents the belt from coming into close contact with the rollers, effectively preventing the occurrence of scratches. can do.

Furthermore, when the belt and the rollers are in close contact, especially when the belt width is wide, the thrust force increases when the photoreceptor belt 11 is shifted to one side, so it may be difficult to correct the meandering. However, if some of the short fibers F, F, ... are exposed from the surface of the cylindrical member 17, the thrust force when the photoreceptor belt 11 is shifted is reduced by avoiding close contact between them. Therefore, meandering correction can be carried out smoothly.

Furthermore, when the belt and roller are in close contact, the coefficient of friction between them is mainly determined by the interfacial state, and the interfacial state changes sensitively to changes in temperature and humidity. However, since electrophotographic devices are used in a wide range of environments, from high-temperature and humid conditions to low-temperature and dry conditions, if left as is, there is a risk that the coefficient of friction will change drastically and the running state will become unstable. On the other hand, short fiber F,
When F,... are exposed between the contact surfaces, the grip force due to the intervening short fibers F, F,... acts between the belt and the rollers, greatly contributing to the frictional force, and this grip The force is mainly determined by the stiffness of the short fibers F, F, ... and the material forming the back surface of the photoreceptor belt 11, and the viscoelastic properties of the elastic body of the cylindrical member 2b. Within the range of environmental changes, it is not affected much by temperature and humidity.

[0044] As in the above embodiment, short fibers F,
When F, . . . are oriented approximately in the roller axis direction (x-axis direction in the figure), manufacturing is easy. That is, when oriented in the z-axis direction in the figure, it is necessary to cut a rubber plate in which the short fibers F, F, . . . are oriented parallel to the plate surface into strips, and then paste the strips together. On the other hand, as in this embodiment, x
When oriented in the axial direction, it can be easily manufactured by extruding a hose material mixed with short fibers F, F, ... with a die having parallel parts, and the manufacturing cost can be reduced. There are advantages.

(Second Example) Next, regarding the second example,
This will be explained based on FIGS. 5 and 6. Also in this example,
The configuration of the electrophotographic apparatus A is the same as that of the first embodiment. FIG. 5 shows a vertical cross-sectional structure of the first driven roller 13 of the photoreceptor belt drive device 10 in this embodiment, and the basic structure of the shaft member 16, cylindrical member 17, and each flange member 18, 18 is as described above. Although it is similar to the first embodiment, in this embodiment, each short fiber F, F,... in the cylindrical member 17 is connected to the roller shaft (
Figure 6 is a cross-sectional view (the scale is different from Figure 5 above).
As shown in , it is oriented so as to have a constant inclination also with respect to the circumferential direction (the y-axis direction in the figure). That is, in this example, by extruding a hose mixed with short fibers F, F, ... through a parallel part and a die tapered so that the diameter increases from the parallel part, Each short fiber F, F,... is randomly distributed but averaged in the roller axis direction (x-axis direction)
The short fibers F, F, . There is an advantage that running resistance can be further reduced.

(Third Embodiment) Next, a third embodiment will be explained based on FIG. 7. FIG. 7 shows the first example in the third embodiment.
The longitudinal cross-sectional structure of the driven roller 13 is shown, and in this embodiment, each short fiber F, F, ... in the cylindrical member 11 has a constant inclination with respect to the roller axis (x-axis direction), It is oriented symmetrically with respect to the center line zo of the first driven roller 13 and inclined outward with respect to the belt rotation direction of the first driven roller 13, and a part thereof is the cylindrical member 1
It is exposed on the surface of 6. therefore,
In the third embodiment, the short fibers F, F, ... exposed on the surface of the first driven roller 13 are tilted outward so as to be symmetrical with respect to the center in the roller axial direction, so that they are not exposed to light. body belt 1
Tension that tends to displace the photoreceptor belt 11 outward in the width direction is generated on both sides of the central portion in the length direction of the belt 1, and the so-called waving phenomenon during belt running is prevented as much as possible. be.

[0047] Here, in the above first to third embodiments,
When the short fibers F, F, ... are aramid fibers, aramid fibers have high rigidity, good sliding properties at high PV values, and a wide stability range against temperature changes. Even when used under such a concentrated load, it is possible to have both high gripping force and low thrust force, and therefore to be highly effective.

[0048] In the above first to third embodiments, the first,
Although the second driven rollers 13 and 14 are short fiber mixed rollers, the present invention is not limited to the above embodiments. For example, only the first driven roller 13 is short fiber mixed rollers. It may also be a la. Furthermore, any of the rollers 12 to 14 may be rollers containing short fibers.

Further, as in each of the above embodiments, the short fiber mixed roller is provided with flange members 18, 18 as belt guide members for regulating the lateral movement of the photoreceptor belt 11 (flat belt).
Even in the case where the exposed short fibers F, F, ... in each of the above embodiments are present between the roller belt, the thrust force when the belt shifts to one side is reduced, and damage to the belt end is prevented. Precise driving of the photoreceptor belt 11 can be realized while effectively preventing the occurrence of wrinkles. Note that it is not necessary to provide the belt guide member on the roller side as in each of the above embodiments; for example, a ring-shaped convex portion may be provided on the back surface of the photoreceptor belt 11, and a groove portion may be provided on the roller side. It may be configured to have a belt guiding function by fitting the portion and the groove portion.

The present invention is not limited to flat belt driving rollers or flat belt driving devices used in electrophotographic processes as in the above embodiments, but is applicable to rollers for general mechanical devices. However, especially when used in an electrophotographic process, the photoreceptor belt 11 and transfer conveyance belt 2
Since the precision drive of 1 is performed, image forming characteristics can be maintained well, and therefore, remarkable effects can be exhibited.

[0051]

As explained above, according to the invention of claim 1, short fibers are mixed into the surface of the roller, the short fibers are oriented approximately in the axial direction of the roller, and further, A portion of the short fibers is exposed on the roller surface, which prevents the belt from being damaged by foreign matter by avoiding close contact between the belt and the roller, reduces the coefficient of friction, and protects against changes in temperature and humidity. It is possible to achieve stabilization and reduce the thrust force when the belt shifts to one side, and also to facilitate production for orientation of short fibers.

According to the second aspect of the invention, short fibers are mixed into the surface of the roller, and the short fibers are oriented at a constant inclination with respect to the axial direction and the circumferential direction of the roller. In addition, some of the short fibers are exposed on the roller surface, which not only prevents the belt from being damaged by foreign objects, improves sliding characteristics, and reduces belt thrust force, but also increases belt running resistance. can be significantly reduced.

According to the invention of claim 3, in the invention of claim 2, since the rollers are oriented symmetrically on both sides with the central part in the axial direction as the border, damage to the belt caused by foreign objects can be prevented. In addition to the effects of prevention, improvement of sliding characteristics, and reduction of the thrust force of the belt, it is possible to generate tension in the width direction of the belt, and therefore, it is possible to effectively prevent the phenomenon of belt waving.

According to the invention of claim 4, the above-mentioned claim 1,
In the invention of 2 or 3, since the short fibers are formed of aramid fibers, the aramid resin exhibits good sliding properties at a high PV value and stability against temperature changes against concentrated loads on the short fibers. In addition, due to its good heat resistance, the short fibers can be polished with a rubber grindstone or the like without damaging them during production, thereby facilitating production.

According to the invention of claim 5, in the flat belt drive device, at least one roller
Since the flat belt according to the second or third invention is used, it is possible to improve the belt running characteristics by improving the sliding characteristics between the roller and the belt.

According to the invention of claim 6, in the invention of claim 5, since a belt guide member is provided on the flat belt and/or the roller, the thrust force when the flat belt is shifted to one side is reduced. It is possible to prevent belt meandering and achieve precision driving while preventing damage to the belt guide member and belt end.

According to the invention of claim 7, in the invention of claim 5 or 6, since the flat belt is a photoreceptor belt or a transfer conveyance belt, when used in an electrophotographic apparatus where environmental conditions vary widely. Also, image forming characteristics can be improved by precisely driving the flat belt.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a first driven roller of a photoreceptor belt device in a first embodiment.

FIG. 2 is a front view showing the overall configuration of the electrophotographic apparatus.

FIG. 3 is a perspective view of an elastic plate in the first embodiment.

FIG. 4 is a perspective view showing a state in which an elastic plate is wound around the first driven roller in the first embodiment.

FIG. 5 is a longitudinal sectional view of the first driven roller in the second embodiment.

FIG. 6 is a cross-sectional view of the first driven roller in the second embodiment.

FIG. 7 is a longitudinal sectional view of the first driven roller in the third embodiment.

[Explanation of symbols]

A Electrophotographic device 10 Photoreceptor belt device (flat belt drive device) 11 Photoreceptor belt (flat belt) 12 Drive roller 13 First driven roller (flat belt drive roller) 17
Cylindrical member 18 Flange member (belt guide member) 20 Transfer conveyance belt device (flat belt drive device) 21 Transfer conveyance belt (flat belt) F Short fiber

Claims (7)

[Claims] 1. A flat belt driving roller for winding and driving a flat belt, at least a surface portion of which is formed of an elastic material such as rubber mixed with a large number of short fibers; A roller for driving a flat belt, characterized in that the fibers are substantially oriented in the axial direction of the roller, and a portion of the fibers are exposed from the surface of the roller. 2. A flat belt driving roller for winding and driving a flat belt, at least a surface portion of which is formed of an elastic material such as rubber mixed with a large number of short fibers, The fibers are oriented with a certain inclination in the axial direction of the roller and in the circumferential direction of the roller, and some of the fibers are
A flat belt drive roller characterized by being exposed from the surface of the roller. 3. The flat belt driving roller according to claim 2, wherein the short fibers are oriented symmetrically with respect to a substantially central portion in the axial direction of the roller. Roller for flat belt drive. 4. The flat belt driving roller according to claim 1, 2 or 3, wherein the short fibers are aramid fibers. 5. A flat belt drive device configured to drive a flat belt by winding it around a plurality of rollers, wherein at least one of the plurality of rollers is driven by a flat belt wound around a plurality of rollers. A flat belt drive device characterized in that it is the roller according to , 2 or 3. 6. The flat belt drive device according to claim 5, wherein the flat belt and/or the rollers are provided with belt guide members for regulating lateral movement of the flat belt. Drive device. 7. The flat belt drive device according to claim 5, wherein the flat belt is a photoreceptor belt or a transfer conveyance belt.