JPH04133929A - belt drive device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a belt drive device in which meandering of a flat belt is corrected by displacement of a meandering adjustment roller.

(Prior Art) Conventionally, for example, in an electrophotographic device, a photoreceptor layer or a dielectric layer is formed on the surface of a plurality of roller members arranged substantially parallel to each other in order to make the device lighter and more compact. It is known to span a flat belt and use the flat belt as a photoconductor belt or a transfer conveyance belt instead of a photoconductor drum.

However, flat belts used for such purposes are often made of plastic film, metal foil, or other materials with low elongation and high strength as a base material. Therefore, this type of flat belt does not easily deform elastically, so it absorbs dimensional errors in related parts, installation errors in roller members, unbalanced belt tension, uneven belt circumference, etc. by deforming the belt itself. As a result, there was a problem in that meandering was likely to occur when driving on flat roads.

However, in such an electrophotographic apparatus, high precision and high resolution are required in order to perform accurate image formation, so it is necessary to prevent the flat belt from meandering.

As a conventional technique for preventing belt meandering, for example, as disclosed in Japanese Utility Model Application Publication No. 58-110609, one roller is used as a meandering adjustment roller, and meandering is detected by a belt position sensor. Detected by means such as
It is known that when meandering occurs, the meandering is corrected by displacing the shaft portion of a meandering adjustment roller according to the amount of meandering.

(Invention or problem to be solved Ifi) However, when such a belt drive device is used in an electrophotographic process such as an organic photoreceptor belt or a transfer conveyance belt, it is particularly difficult to use thin parts such as metal foil or plastic film. Since it is used as a tension layer, it has the following problems.

That is, when attempting to correct the meandering of such a thin belt by displacing the shaft of the meandering adjustment belt, if the amount of displacement of the shaft is too large, wrinkles may occur on the belt surface.
This causes the problem of the belt flapping. However, for example, in an organic photoreceptor belt, the area around the belt drive device is charged and exposed.

Devices for various processes such as development, transfer, and cleaning are arranged, and in order to perform each process smoothly, it is necessary to eliminate wrinkles and flapping on the belt surface.

The present invention was made in view of such problems, and its main purpose is to solve the problem that the friction coefficient between the belt contact surface of each roller plays a major role in the running characteristics of the belt. By adjusting the frictional characteristics of the material that forms the belt contact surface, the amount of displacement of the meandering adjustment roller shaft required for meandering correction is reduced, thereby effectively preventing wrinkles and flapping on the belt surface during meandering correction. The purpose is to prevent it.

On the other hand, in the above-mentioned belt drive device, foreign matter such as carrier, toner, and paper dust during development wraps around the back side of the belt, so the belt sliding surface of the roller is made of a material with high elasticity such as metal or plastic material. This poses a problem in that the belt is more likely to be damaged by foreign objects.

The next object of the present invention is to use a soft elastic material such as rubber with a large coefficient of friction as the material for forming the belt contact surface of the roller, and to adjust the coefficient of friction to prevent the belt from being damaged. The purpose is to prevent belt wrinkles and flapping.

(Means for Solving the Problem) In order to achieve the above object, the solution of the present invention is to make the coefficient of friction of the meandering adjustment roller member larger than the coefficient of friction of the other roller members.

Specifically, the invention according to claim (1) provides a flat belt and a plurality of rollers around which the flat belt is stretched, at least one of which serves as a meandering adjustment roller member whose shaft portion is displaceably supported. a meandering detection means for detecting meandering of the flat belt; and receiving an output of the meandering detection means, displacing a shaft portion on the side of the meandering adjustment roller so as to move the flat belt in a direction opposite to the meandering direction. It is assumed that a belt drive device is provided with a roller displacement means for moving the belt.

The contact surface of the meandering adjustment roller member is formed of a material having a coefficient of friction with the flat belt that is larger than a coefficient of friction between the belt and the belt contact surface of the other roller member. be.

The means taken by the invention of claim (2) are the same as those of claim (1).
In the invention, the belt contact surface of the meandering adjustment roller member is formed of an elastic material such as rubber, and the belt contact surface of the other roller member is formed of an elastic material mixed with short fibers made of organic material. It is.

The means taken by the invention of claim (3) are the same as those of claim (1).
Or in the invention of (2), at least the opening of the flat belt
The contact surface is made of metal or plastic material.

(Function) With the above configuration, in the invention of claim (1), the coefficient of friction between the belt contact surface of the meandering adjusting roller member and the flat belt is the same as that between the belt contact surface of the other roller member and the flat belt. Since the coefficient of friction is larger than the friction coefficient of While the force of
On the other roller members, the resistance force against the meandering correction is small, and the meandering correction can be smoothly performed.

As a result, the displacement plate of the meandering adjustment roller member for meandering correction becomes smaller, which, together with smoother movement of the flat belt, prevents wrinkles and flapping on the belt surface.

In the invention of claim (2), in the invention of claim (1), the belt contacting surface of the meandering adjustment roller member is formed of an elastic material such as rubber, and the belt contacting surface of the other roller member is formed of short fibers. The belt contact surfaces of all roller members are basically formed of a soft elastic material, and the coefficient of friction between the belt contact surface of the meander adjustment roller member and the flat belt is Since the coefficient of friction between the belt contact surface of the other roller member and the flat belt is higher, the effect of the invention of claim (1) can be obtained, and
Even when foreign matter gets around to the back side of the flat belt while the belt is running, damage to the flat belt is suppressed.

In the invention of claim (3), since the roller contact surface of the flat belt is made of a material harder than an elastic body such as metal or plastic, damage to the flat belt due to biting of foreign objects is further suppressed. become.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the entirety of a flat belt drive device housed in an electrophotographic apparatus according to the present invention, which is a three-way photosensitive belt drive device. In FIG. 1, 1, 2, and 3 are the first, second, and 30th-ra part shrines, respectively, and the shaft part side 1
a, 2a, 3a, and an elastic body such as rubber formed concentrically with the shaft members 1a, 2a, 3a and having a slightly larger diameter, excluding both left and right ends of the shaft sides 1a, 2a, 3a. It consists of roller parts 1b, 2b, and 3b.

Further, a photoreceptor belt 4, which is a flat belt in the present invention and has a photoreceptor layer formed on the surface of a base material, is runnably stretched over each of the roller members 1.2.3. The photoreceptor belt 4 functions as a photoreceptor of the electrophotographic apparatus.

Further, as the base material of the photoreceptor belt 4, for example, biaxially oriented polyester is used, and the tensile modulus is 20.
It is set at 0kg/ll1m2 or more.

The 10th round part shrine 1 has a shaft member 1a linked to a drive shaft of a drive motor 5 so that the driving force of the drive motor 5 can be transmitted, and functions as a so-called drive roller.

The 20th round part shrine 2 is a so-called driven roller, and its axis is inclined with respect to the axis of the 10th round part shrine 1. For example, only the A-direction side shaft end of the shaft member 2a is slightly displaced (for example, by one stroke) in the C direction with respect to the horizontally parallel position with the 10th-R section 1.

30th-A part) A3 is a meandering adjustment roller member as used in the present invention, and its axis is arranged substantially parallel to the axis of the roller part side 1. Further, the 30th La part shrine 3 is given a biasing force in the C direction by springs 3c, 3c disposed at both left and right shaft ends, and the tension of the photoreceptor belt 4 is adjusted by this biasing force. It is supposed to be done.

By arranging each roller part tl'l, 2.3 in this way, each roller part tTA'l, 2.
The photoreceptor belt 4, which is stretched around the photoreceptor belt 3, is configured to always meander in the A direction.

Here, the above-mentioned 1. 20th - Roller part 1 of Ra part shrines 1 and 2
b and 2b are made of rubber mixed with 20% by weight of short fibers of 2 mm length and polished on the surface.
- The roller portion 3b of the roller portion 3 is formed solely of an elastic body such as, for example, EPDM crosslinked rubber. In addition, the above EPD
In addition to the M-based crosslinked rubber, a material with a high friction coefficient and low wear resistance, such as urethane rubber, can be used.

That is, 1st. 20th-Rora part 1b of Ra part shrines 1 and 2,
By mixing short fibers of an organic material into the elastic body of 2b and polishing the roller surface, the friction coefficient of the belt contact surface is reduced as described later, and the third part, which is on the meandering adjustment roller side, is
The friction coefficient between the 0-roller member 3 and the photoreceptor belt 4 is made larger than the friction coefficient between the other roller portion side 1.2 and the photoreceptor belt 4.

Further, the shaft end portion of the shaft member 3a of the 30th member 3 is connected to the second
As shown in the figure and FIG. 3, a bushing 7 which is a bearing member
The lower frame 8a is rotatably supported by the lower frame 8a through the slide bearing 9, and the upper frame 8b is attached and fixed to the movable member 6 through the slide bearing 9. and are engaged so that they can be separated, and this lower frame 8a
, by the upper frame 8b and the slide bearing 9, the 30th
- A roller support part 8 is configured to support the shaft end of the shaft member 3a of the roller member 3 in a direction perpendicular to the rotational axis. On the other hand, at a position inside the mounting position of the lower frame 8a of the shaft member 3a of the 30th-La part +;
- It is rotatably arranged independently from the ring member 3, and a ring member 12 is attached at the outer position.

The meandering detection member 11 has a tapered portion 11a whose outer diameter on the side of the roller portion 3b is the same as or slightly smaller than the outer diameter of the roller portion 3b, but whose diameter increases as it moves away from the end face. When this occurs, the photoreceptor belt 4 rides on the meandering detection member 11 due to the meandering displacement.

The meandering detection member 11 is connected to the other end of the assembled part side 13 whose one end is attached and fixed to the fixed part S, and the meandering displacement of the photosensitive belt 4 causes the photosensitive belt 1-4 to move to the meandering detection member. 11 and rotational torque is applied to the meandering detection member 11, the string portion side 13 is wound around the meandering detection member 11 due to the rotation of the meandering detection member 11, and the 30th-
The A-direction shaft end of the shaft member 3a of the la member 3 is displaced in the direction away from the shaft portion ttla of the 10th la part shrine 1 (direction B in FIG. 1). That is, by displacing the shaft member (shaft portion) 3a of the 30th member 3, the photoreceptor belt 4 is wound along the circumferential direction of the 30th member 3 in a direction opposite to the direction in the figure. It is being moved to This constitutes a roller displacement means 14 that displaces the shaft portion of the shaft member 3a so as to eliminate meandering when rotational torque due to meandering acts on the meandering detection member 11. That is, when the shaft end of the shaft member 3a is displaced in the B direction, a meandering component in the direction opposite to the input direction is generated in the photoreceptor belt 4, which cancels out the initial meandering component (A direction component). The shaft end portion of the shaft member 3a will be displaced until.

Further, as shown in FIG. 4, a spring 15 is connected to the ring member 12 at the end of the shaft portion tTA' 3a.
The string member 13 is always biased in a direction opposite to the direction of displacement due to the winding operation, and the spring 15 is designed to suppress displacement of the shaft end portion of the shaft member 3a by more than a predetermined amount. . With this configuration, when the meandering component in the opposite direction due to the displacement of the shaft end of the shaft member 38 becomes larger than the initial meandering component, the photoreceptor belt 4 starts meandering in the opposite direction and runs onto the meandering detection member 1. Since the amount decreases,
The rotational torque of the meandering detection member 11 is also reduced, and as a result, the amount of displacement of the shaft end portion of the shaft member 3a by the spring 15 is also reduced.

Note that the movement of the meandering detection member 1 to the outside of the roller end is restricted by a stopper 16.

In other words, 1st and 30th - 2nd for 1 and 3
Due to the inclined arrangement of the 0-A member 2, the photoreceptor belt 4 is always kept in the A position.
A force acts to displace the photoreceptor belt 4 in the direction of
When the end of the photosensitive belt 4 rides on the tapered part 11a of the meandering detection member 11 due to the displacement, as shown in FIG.
Due to the frictional force acting between the photosensitive belt 4 and the meandering detection member 11, the meandering detection member 11 is rotated with respect to the shaft member 2a, and the string portion side 13 is wound up by the rotation. By winding up this string part side 13, the shaft member 3a of the 30th-ra member 3 where the material 11 is arranged.
The shaft end is displaced, and the further displacement of the photoreceptor belt 4 is controlled by the displacement, and the spring force accompanying the expansion of the spring 15 acts due to the displacement of the shaft end, and the string member The balance between the winding force of 13 and the spring force of 5 regulates the amount of displacement of the 30th section 3, and maintains the end of the photoreceptor belt 4 at a certain constant position. ing.

Therefore, in the above embodiment, the first. 20th-ra member 1
, 2 roller parts 1b, 2b are made of hard rubber containing short fibers with polished surfaces, while the roller part 3b of the 30th roller member 3 (meandering adjustment roller member) is made of a soft rubber material (the above-mentioned implementation). In the example, the friction coefficient between the belt contact surface of the 30th lug 3 and the photoreceptor belt 4 is 1. Since the coefficient of friction between the belt contact surface of No. 2 and the photoreceptor belt 4 is larger than the coefficient of friction between the belt contact surface of No. 2 and the photoreceptor belt 4, when the photoreceptor belt l-4 meanders, the roller end displacement means 14 When the shaft end of the shaft member 3a of the member 3 is displaced in the direction B in the figure, a large force acts on the 30th-ra portion 3 to correct the meandering of the photoreceptor belt 4, while other The resistance force on the roller member 1.2 to correct the meandering is small, and the meandering can be corrected smoothly.

As a result, the amount of displacement of the shaft member 3a of the 30th sleeve member 3 for meandering correction can be reduced, and together with the smoothness of the following movement of the photoreceptor belt 4 during meandering correction, the belt surface This can effectively prevent the occurrence of wrinkles and flapping.

Furthermore, as a result, high-quality images without image shift can be obtained in processes that require precision, such as electrophotography.

In the above-mentioned embodiments, an example is explained in which the application is applied to a photosensitive belt drive device of an electrophotographic apparatus, but the present invention is not limited to this, and the present invention is applicable to a drive device of a transfer conveyance device or a regular flat belt. The same can be applied to drive devices.

Further, the present invention is not limited to the belt meandering correction method as in the above embodiments, and for example, the meandering of the belt is detected by an optical sensor, and the shaft of the meandering adjustment roller is adjusted according to the amount of meandering. It can also be applied to devices that displace the .

Further, in the above embodiment, the roller portions 1b to 3b of each of the roller members 1 to 3 are made of an elastic material, but for example, the roller portions 1b to 3b of the roller members 1 to 3 are made of an elastic material. Second
0-Roller portion 1b of roller members 1 and 2.

2b is formed of metal, and the roller portion 3b of the 30th roller member 3
By forming only the elastic body, the coefficient of friction with the belt may be made different. However, in this case, in the electrophotographic process as in the above embodiment, there is a risk that foreign substances such as carrier, toner, and paper powder in the developer may get around to the back side of the photoreceptor belt 4 and damage the photoreceptor belt 4. arise.

Here, as in the above embodiment, the roller portion 3a (belt contact surface) of the 30th roller member 3 is formed of an elastic material, and the
．． 20th - Short fibers are mixed into the elastic bodies of the roller parts 1a and 2a of the 20th roller members 1 and 2, and the belt contact surfaces of all the roller members 1 to 3 are basically made of a soft elastic material. By making the friction coefficient between the belt contact surface of the meandering adjustment roller member 3 and the photoreceptor belt 4 larger than the friction coefficient between the belt contact surface of the other roller members 2 and the photoreceptor belt 4. In addition, it is possible to maintain smooth meandering correction as described above, and to prevent damage to the photoreceptor belt 4 as much as possible.

In addition, as in the above embodiment, when the roller contact surface of the photoreceptor belt 4 is made of a material harder than an elastic material such as metal or plastic, the photoreceptor belt 4 may be damaged due to foreign matter biting as described above. This has the advantage of further suppressing damage.

(Experiment example) Experimental examples of the present invention will be described below.

First, the coefficient of friction between the belt contact surface of the roller member and the flat belt was measured. That is, as shown in FIG. 6, the test belt TBI, whose one end is connected to the load cell Lc, is passed around the roller R+, and a weight Dv (as T2) of the load T2 is placed on the tip of the test bell l-TBI. ,0.38
5Kg and 1. ．． 75Kg (using two levels) is applied,
It is calculated based on the following formula (% formula %) from the load T1 applied to the load cell Lc when a roller Ri having a diameter of 16 mm and a roller length of 270 man is rotated at a predetermined circumferential speed (36 mm/sec).

As a result, the measured values of the friction coefficient μ' for each combination of roller material and belt material are shown in Table 1 below.

Table 1 Next, Table 2 below shows the belt for meandering adjustment when the material of the belt contact surface of each roller member 1 to 3 and the material of the roller contact surface of the photoreceptor belt 4 in the above embodiment are changed. In the table, A, B, and C indicate EPDM rubber, short fiber-containing rubber, and aluminum, respectively, in Table 1 above.

In this experiment, the belt width was 250 mm, the belt circumference was 140 mm, and the belt tension was 2 times the spring force of springs 3c and 3c in the above example.
Kg.

As shown in Table 2 above, the meandering adjustment roller is
If the belt is made of DM rubber and the drive roller and tension roller are made of rubber mixed with short fibers, the belt does not wrinkle or flap, and the displacement of the shaft end of the meandering adjustment roller is small. 1 and 2), and in other combinations, the belt wrinkles or flaps. In addition, when each roller is made of rubber containing short fibers, the belt does not wrinkle or flap, but
The amount of shaft end displacement is large. That is, the effects of the present invention are clearly demonstrated.

(Effects of the Invention) As explained above, according to the invention of claim (1), the meandering adjustment roller member is provided, and the flat belt is stretched around a plurality of roller members, so that when the flat belt meanders, the meandering In a belt drive device that corrects meandering by displacing the shaft portion of the adjusting roller member, the belt contact surface of the meandering adjusting roller member has a friction coefficient with the flat belt that is lower than that of the other roller portion. Since it is made of a material that has a larger coefficient of friction than the friction coefficient between the belt contact surface and the flat belt, it is possible to increase the belt meandering correction force by the meandering adjustment roller and to smoothen the movement of other roller members. When the flat belt meanderes, the amount of displacement of the meandering adjustment roller member can be reduced, and the generation of wrinkles and flapping of the belt can be effectively prevented.

According to the invention of claim (2), in the invention of claim (1), the belt contacting surface of the meandering adjustment roller member is formed of an elastic material, while the belt contacting surface of the other roller member is formed of short fibers. Therefore, while maintaining the effect of the invention of claim (1) above, by forming all the belt contact surfaces on the roller side with a soft elastic material, foreign matter can be removed from the back side of the belt. It is possible to effectively prevent damage to the belt due to the belt being wrapped around the belt.

According to the invention of claim (3), the above claim (1) or (
In the invention of 2), since the roller contact surface of the flat belt is made of metal plastic material, the surface hardness is maintained higher than that of each roller member made of an elastic material, thereby preventing scratches on the flat belt. It is possible to improve the effectiveness.

[Brief explanation of drawings]

Figures 1 to 5 show an embodiment of the present invention, with Figure 1 being a schematic perspective view of the belt drive device, Figure 2 being a longitudinal sectional front view of the vicinity of the meandering detection member, and Figure 3 being viewed from inside. Perspective view, 4th
The figure is a perspective view seen from the outside, and FIG. 5 is a diagram for explaining the operation of the roller displacement means. FIG. 6 is a diagram schematically showing the configuration of a friction coefficient n1 constant machine that measures the friction coefficient between the belt contact surface of the roller member and the flat belt. 1 10th R member 2 20th R member 3 30th R member (meandering adjustment roller part side) 4 Photoreceptor belt (flat belt) 11 Meandering detection member (meandering detection means) 14 Roller displacement means Fig. figure

Claims (3)

[Claims] (1) A flat belt, a plurality of roller members around which the flat belt is stretched, at least one of which serves as a meandering adjustment roller member whose shaft portion is movably supported, and detecting the meandering of the flat belt. A belt drive device comprising: a meandering detecting means; and a roller displacing means receiving an output of the meandering detecting means and displacing the shaft portion of the meandering adjusting roller member so as to move the flat belt in a direction opposite to the meandering direction. , the belt contact surface of the meandering adjustment roller member is formed of a material having a coefficient of friction with the flat belt larger than a coefficient of friction between the belt contact surface of the other roller member and the flat belt; A belt drive device featuring: (2) The belt contact surface of the meandering adjustment roller member is formed of an elastic material such as rubber, and the belt contact surface of the other roller members is formed of an elastic material mixed with short fibers made of an organic material. The belt drive device according to item (1). (3) Claim (1) or (3) wherein at least the roller contact surface of the flat belt is formed of metal or plastic material.
2) The belt drive device described.