JPH0656294A - Endless belt conveying device for image forming device - Google Patents

Abstract

PURPOSE:To precisely control the meandering of a belt at a low cost. CONSTITUTION:An image forming device stretched and driven with an endless belt between multiple rolls including at least a driving roll and a tension applying roll is provided with tilting mechanisms 40, 37, 47, 50 tilting the shaft of at least one roll 14 in the perpendicular direction to the tension application direction and cams 48, 49 driving the tilting mechanisms, and the cams 48, 49 are formed into the shape to constantly increase or decrease the meandering speed of the endless belt against the rotation angle of the cams 48, 49.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endless belt used as a photoconductor belt, a transfer belt, an intermediate transfer belt, a continuous paper conveying belt, etc. in an image forming apparatus such as a copying machine, a facsimile, a printer and the like which uses an electrophotographic method. Concerning a carrier device.

[0002]

2. Description of the Related Art In the above-mentioned image forming apparatus, a charge corotron, an exposure device, a developing device, a transfer corotron, a cleaning device, a discharge lamp and the like are arranged around the image carrier, and the image carrier is carried by the charge corotron. After the body is uniformly charged, an electrostatic latent image is formed on the image carrier by the exposure device, this electrostatic latent image is developed into a toner image by the developing machine, and then this toner image is transferred. An image is formed by a series of processes in which the toner is transferred to a material by a transfer corotron, the residual toner on the image carrier is removed by a cleaning device, and then the charge of the image carrier is removed by a charge eliminating lamp.

In the image forming apparatus, there is a system in which an endless belt conveyor is used for an image carrier, a transfer material carrier, an intermediate transfer member, a continuous paper carrier and the like. This endless belt conveying device is configured to drive the endless belt by stretching it around a plurality of rolls having at least a driving roll and a tension applying roll, but the parallelism between the rolls according to the arrangement of the rolls and the cylindrical accuracy of the rolls. , A phenomenon in which the belt moves in a direction perpendicular to the conveying direction due to a difference in circumferential length between both ends of the belt,
That is, a meandering phenomenon occurs, and when the meandering phenomenon occurs, the image formed on the belt or the image transferred on the belt is biased, and thus there is a problem that a good image cannot be obtained.

Conventionally, in order to solve this problem, Japanese Unexamined Patent Publication No. 62-27209 and Japanese Utility Model Laid-Open No. 59-87063.
In the publication, the belt meandering amount is detected, and the belt meandering is corrected by tilting the roll using a tilting mechanism according to the detected amount.

This tilting mechanism will be described with reference to FIG. 5. In FIG. A, between the drive roll 1 and the tension applying roll 2,
The endless belt 3 is stretched, and as shown in FIG. B, an eccentric cam 5 is in contact with the rotating shaft 4 of the tension applying roll 2,
When the eccentric cam 5 is rotated, the tension applying roll 2 is tilted by the angle α, which causes the belt to move in the A direction. Figure C
Indicates an eccentric cam 5, and a disc having a center C1 and a radius r is rotated about a rotation center C2. The relationship between the rotation angle θ of the eccentric cam 5 and the displacement x is a sine curve as shown in FIG. The control is performed by using the portion of B in the figure which is relatively close to the straight line.

[0006]

However, in the conventional system using the tilting mechanism, the relationship between the rotation angle θ of the eccentric cam and the corrected meandering speed V of the belt becomes a curve shown in FIG. For the same corrected meandering speed change amount ΔV ₁ depending on the position of, the rotation angle change amount is Δθ ₁ ,
It becomes Δθ _{2 and the} corrected rotation angle changes. Therefore,
Even if the meandering speed is detected, an error occurs unless the correction rotation angle is changed depending on the position of the rotation angle θ of the eccentric cam, and there is a problem that the correction accuracy decreases.

Conventionally, in this method, control is performed mainly for the purpose of preventing the belt from falling off due to the meandering of the belt, and the belt position is controlled so as to have a constant value. Accordingly, the eccentric cam is rotated by a certain angle, and then the rotation amount of the eccentric cam is gradually reduced and stabilized in accordance with the meandering direction and the belt position. Therefore, there is no problem even if the cam characteristic is not a perfect straight line as shown in FIG.

However, since the amount of change in the meandering speed is not constant with respect to the amount of change in the rotation angle of the eccentric cam as described above, there is a problem that the control is unstable and it takes time to converge. Further, in the color image forming apparatus, if the accuracy of the meandering control (for example, 0.1 mm) is poor, color misregistration may occur in the color image, and in order to solve this problem, when performing control with high accuracy, The rotation angle of the eccentric cam must be detected by a sensor or the like, and control must be performed in an amount according to the angle, resulting in complicated control.

An object of the present invention is to solve the above problems and to provide an endless belt conveying device in an image forming apparatus capable of highly accurately and inexpensively controlling the meandering of a belt.

[0010]

In order to achieve the above object, an endless belt conveying device in an image forming apparatus of the present invention stretches an endless belt between a plurality of rolls having at least a driving roll and a tension applying roll. An image forming apparatus to be driven includes a tilting mechanism for tilting at least one roll shaft in a direction perpendicular to a tension applying direction, and a cam for driving the tilting mechanism. The cam is endless with respect to a cam rotation angle. It is characterized in that the meandering speed of the belt is constantly increased or decreased.

[0011]

In the present invention, the belt meandering speed is calculated,
The cam rotation angle to be corrected is calculated based on this meandering speed, and the cam is rotated so that the belt meandering amount becomes zero. At this time, since the cam has a shape in which the meandering speed of the endless belt is increased or decreased with respect to the cam rotation angle, the correction can be performed with high accuracy.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 is an overall configuration diagram of a color image forming apparatus in which the present invention is applied to a transfer material transport belt. The present invention is not limited to such an image forming apparatus,
The present invention can be applied to a monochromatic image forming apparatus, and is not limited to the transfer material conveying belt, but can be applied to an intermediate transfer member belt and a transfer material conveying drum.

The transfer material conveying belt 11 is formed of an endless belt coated with a dielectric film, is stretched around a plurality of rolls 12, 13, 14, 15 having at least a driving roll 12 and a tension applying roll 14, and is shown by an arrow in the figure. It is rotated in the A direction. Four sets of image forming units K, Y, M, and C for black, yellow, magenta, and cyan are arranged facing the upper surface of the transfer material transport belt 11.

Each of the image forming units K, Y, M, and C includes an image carrier 16 composed of a photosensitive drum, a charge corotron 17, a latent image writing means 18, a developing device 19, a transfer corotron 20, and an image carrier cleaner. 21, a transfer material discharging corotron 22 is provided on the downstream side of the image forming units K, Y, and M, and the image carrier 16 is rotated in the direction of the arrow in the figure.

A peeling corotron 23 and a peeling claw 24 are provided on the downstream side of the final stage image forming unit C, and a fixing device 25 is further provided. On the upstream side of the drive roll 12, a conveyor belt static elimination corotron 26 and a cleaning blade 27 are arranged. Further, on the downstream side of the drive roll 12, a suction corotron 30 is arranged inside the transfer material conveying belt, and a transfer material suction roll 31 a is arranged facing the suction corotron 30. The transfer material in the paper feed tray 28 is transported to the transfer material transport belt 11 by the feed roll 29, and then transferred to the transfer material transport belt 11 by the suction cocorotron 30 and the transfer material suction roll 31a.
Is adsorbed on.

In the above-mentioned color image forming apparatus, the image carrier 16 is uniformly charged by the charge corotron 17, and the latent image writing means 18 exposes the original image to the electrostatic latent image on the image carrier 16. An image is formed. Developing machine 1
At 9, the toner is brought into contact with the surface of the image carrier 16 to form a toner image, and the developed toner image is transferred to the transfer corotron 2.
After transfer to the transfer material on the transfer material transport belt 11 at 0,
A series of image forming cycles is performed by scraping off the toner remaining on the image carrier 16 with the cleaner 21, and this cycle is performed by four image forming units K, Y, and
This is performed by M and C, and a plurality of toner images are sequentially superposed and transferred onto the transfer material that is adsorbed and conveyed by the transfer material conveying belt 11.

Next, the principle of meandering correction according to the present invention will be described. When the meandering correction of the belt 3 is performed by tilting the tension applying roll 2 shown in FIGS. 5A and 5B in the direction perpendicular to the tension direction, the belt meandering speed V is proportional to the meandering correcting roll angle α. Let K ₁ . Further, the meandering speed V is determined by the difference in the circumferential lengths of both side edges of the belt, the parallelism of the rolls, etc., so that the meandering speed ΔV when α = 0. These relationships are V = ΔV−K
_{When the} meandering correction roll angle α is controlled so that it is expressed by ₁ × α and the meandering speed V = 0, the correction roll angle change amount Δ
It suffices that α = ΔV / K ₁ . Therefore, when the tilting mechanism displaces the roll end portion shown in FIG. 5B by the cam, if the cam displacement change amount is ΔX, if the displacement amount is ΔX = L × tan Δα = L × tan (ΔV / K ₁ ), the meandering speed becomes You can control.

When the relationship between the cam rotation angle θ and the meandering speed V is V = ΔV−K ₂ × θ, the meandering speed change amount Δ
The cam rotation angle change amount Δθ for correcting V is Δθ =
It becomes ΔV / K ₂ . Therefore, if this relationship holds for the cam rotation angle θ anywhere, the cam rotation angle change amount Δθ can be easily determined by detecting the meandering speed change amount ΔV.

From the above, ΔX = L × tan (Δθ × K
₂ / K ₁ ), if the relationship between the cam rotation angle change amount Δθ and the cam displacement change amount ΔX is satisfied, the meandering speed change amount ΔV becomes constant with respect to the cam rotation angle change amount Δθ, and its constant is K ₂ . Become. Here, when θ = 0 and X = X ₀ , X = L × tan (θ × K ₂ / K ₁ ) + X ₀ , and a cam shape satisfying this can be obtained.

2A is a plan view of the cam 48 according to the present invention, and FIG. 2B is a cam rotation angle θ of the cam 48 of FIG. 1A.
2C shows the relationship between the cam rotation angle θ and the meandering speed V, and the meandering speed change amount is constant with respect to the cam rotation angle change amount.

FIG. 1 is a perspective view showing an embodiment of the endless belt conveying device of the present invention. Front and rear pair of belt frames 3
A tension applying mechanism 36 is attached to the first and second members 32. The tension applying mechanism 36 includes a bracket 37 fixed to the belt frames 31 and 32, a spring 38 having one end fixed to the inner tip of the bracket 37, and a bracket 3
7 and a slide rail 39 provided outside.
In addition, both ends of the tension applying roll 14 have support arms 40.
The support arm 40 is rotatably supported by a shaft, and a protrusion 41 is formed inside the support arm 40.

The protrusion 41 of the support arm 40 is fitted into the slide rail 39, and the tip 40a of the support arm 40 is fixed to the spring 38. As a result, the support arm 40 is biased in the D direction by the elastic force of the spring 37, and a predetermined tension is applied to the belt.

Further, one end of a release plate 42 is fixed to the spring 38 on the tip end 40a side of the support arm 40, and a bent portion 42a is formed at the other end of the release plate 42, and a release cam is formed on the bent portion 42a. 43 and 44 are abutted. The release cams 43 and 44 are the belt frame 3
A release lever 46 is provided on the cam 43 on the front side belt frame 31 side, which is attached to both ends of a cam shaft 45 penetrating between the first and the second frame 32. With this structure, when the release lever 46 is in the state shown in the drawing, the support arm 40 is urged to apply tension to the belt. When the release lever 46 is tilted when the belt is exchanged, the release plate 4 is released.
2 pulls the support arm 40 against the spring 38 to release the tension acting on the belt.

Further, the bracket 3 of the tension applying mechanism 36
7 is rotatably attached to the belt frames 31 and 32 about a shaft 47, belt moving cams 48 and 49 for controlling the rotation of the bracket 37 are provided, and the tension applying roll 14 is provided. It constitutes a tilting mechanism that tilts the shaft. The shapes of the cams 48 and 40 are the shapes shown in FIG. 2A, and as described above, the cam rotation angle change amount Δ
It is possible to make the meandering speed change amount ΔV constant with respect to θ. The two belt moving cams 48 and 49 attached to both ends of the cam shaft 50 penetrating between the belt frames 31 and 32 are, for example, the support arms on the front side when the cam shaft 50 rotates in the direction A in the figure. The support arm 40 on the back side is arranged so as to rotate in the B direction, and to rotate in the opposite C direction. The camshaft 50 is the motor 5
It is driven to rotate by 1.

The operation of the present invention having the above structure will be described. A belt position and a belt meandering speed are calculated by a belt position sensor (not shown), a cam rotation angle to be corrected is obtained from the relationship of FIG. 2C based on the meandering speed, and a signal is sent to the motor 51 so that the belt meandering amount becomes zero. Output. As shown in FIG. 1, when the cam shaft 50 is rotated in the A direction by driving the motor 51, the support arm 40 on the front side is tilted in the B direction, and the support arm 40 on the back side is rotated in the opposite direction C. The endless belt moves in the E direction as a result. In this way, by controlling the inclination of the tension applying roll 14 in the axial direction, the center position of the belt is corrected to a predetermined position.

In the above embodiment, the tension applying roll 14 is provided with the tilting mechanism for correcting the meandering, but the present invention is not limited to this, and another roll is provided with the tilting mechanism, and this tilting mechanism is provided. You may make it control by the said cam.

Next, another embodiment of the present invention will be described with reference to FIG. FIG. A is a schematic sectional view in which the tension applying roll 14 of FIG. 1 is modified, and FIG. B is an enlarged sectional view.

In this embodiment, the tensioning roll 14
Is formed from an elastic member, and a large number of slits 14a are formed on the surface in the axial direction. The rotating shaft 14b of the tension applying roll 14 is supported by a support arm 40 (only one side is shown) via bearings 52 and 53. A guide member 55 is axially supported via a thrust bearing 54 between the side surface of the tension applying roll 14 and the support arm 40, and a spring 56 is provided between the guide member 55 and the support arm 40. The end portion of is elastically supported by the guide member 55. On the opposite side of the support arm 40, a cam 48 rotated by a motor 51 is provided as in the embodiment of FIG. 1, and the tension applying roll 14 can be tilted. The guide member 55 and the cam may be provided on both sides of the tension applying roll 14.

In the embodiment of FIG. 1, the meandering speed is detected and the roll is tilted accordingly, but in this embodiment, the roll 14 is tilted so that the load applied to the guide member 55 becomes a constant value. Let Here, the relationship between the meandering speed V and the load F applied to the guide member 55 is F = K _F × V (K
_{Since F} is represented by a constant), the same operation as in the embodiment of FIG. 1 can be achieved only by replacing this.

[0030]

As is apparent from the above description, according to the present invention, at least one roll is provided in an image forming apparatus in which an endless belt is stretched and driven between a plurality of rolls having at least a driving roll and a tension applying roll. Has a tilting mechanism for tilting the shaft and a cam for driving the tilting mechanism in a direction perpendicular to the tension applying direction, and the cam has a shape that constantly increases or decreases the meandering speed of the endless belt with respect to the cam rotation angle. Therefore, the meandering control of the belt can be performed with high accuracy and at low cost, and particularly when applied to a color image forming apparatus, a high quality image without color misregistration can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of an endless belt conveyance device of the present invention.

2A is a plan view of a cam according to the present invention, FIG. 2B is a diagram showing a relationship between a cam rotation angle and a cam displacement in the cam shown in FIG. 2A, and FIG. 3C is a relationship between a cam rotation angle and a meandering speed V. Figure

FIG. 3 shows another embodiment of the transfer material conveying device of the present invention,
FIG. A is a schematic sectional view in which the tension applying roll of FIG. 2 is changed, and FIG. B is an enlarged sectional view.

FIG. 4 is an overall configuration diagram of a color image forming apparatus in which the present invention is applied to a transfer material transport belt.

FIG. 5 shows a conventional transfer material conveying device, FIG. A is a side view,
FIG. B is a front view showing the tilting mechanism, FIG. C is a plan view of the eccentric cam, and FIG. D is a view showing the relationship between the rotation angle and the displacement of the eccentric cam.

6 is a diagram showing the relationship between the rotation angle of the eccentric cam of FIG. 5 and the belt meandering speed.

[Explanation of Codes] 11 ... Transfer Material Conveying Belt, 12-15 ... Roll, 48,
49 ... Cams 40, 37, 47, 50 ... Tilt mechanism

Claims (1)

[Claims] 1. An image forming apparatus in which an endless belt is stretched and driven between a plurality of rolls having at least a drive roll and a tension applying roll, and a tilting mechanism for tilting the axis of at least one roll in a direction perpendicular to the tension applying direction. When,
And a cam for driving the tilting mechanism, wherein the cam has a shape that constantly increases and decreases the meandering speed of the endless belt with respect to a cam rotation angle.