JP3082452B2 - Endless belt transport device in image forming apparatus - Google Patents

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 for a photoreceptor belt, a transfer belt, an intermediate transfer belt, a continuous paper transport belt and the like in an image forming apparatus such as a copying machine, a facsimile, a printer, etc. using an electrophotographic method. It relates to a transport device.

[0002]

2. Description of the Related Art In the above-described image forming apparatus, a charge corotron, an exposure device, a developing device, a transfer corotron, a cleaning device, a static elimination lamp and the like are arranged around an image carrier. After the body is uniformly charged, an exposure device forms an electrostatic latent image on the image carrier, and the electrostatic latent image is developed into a toner image by a developing device, and then the 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, and a residual toner on the image carrier is removed by a cleaning device, and then the charge on the image carrier is removed by a charge removing lamp.

In the image forming apparatus, there is a system in which an endless belt transport device is used for an image carrier, a transfer material transporter, an intermediate transfer member, a continuous paper transporter, and the like. In this endless belt transport device, the endless belt is stretched and driven on at least a plurality of rolls having a driving roll and a tension applying roll. However, the parallelism between the rolls due 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 transport direction due to a difference in circumferential length between both side edges of the belt,
That is, when the meandering phenomenon occurs and the meandering phenomenon occurs, an image formed on the belt or an image transferred onto the belt is biased, so that there is a problem that a good image cannot be obtained.

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

[0005] This tilting mechanism will be described with reference to Fig. 5. In Fig. A, between the driving roll 1 and the tension applying roll 2 is provided.
An endless belt 3 is stretched, and as shown in FIG. B, an eccentric cam 5 is in contact with a rotating shaft 4 of the tension applying roll 2.
When the eccentric cam 5 is rotated, the tension applying roll 2 tilts by the angle α, whereby the belt moves in the A direction. Figure C
Denotes an eccentric cam 5 for rotating a disk having a center C1 and a radius r about a rotation center C2. The relationship between the rotation angle θ and the displacement x of the eccentric cam 5 is represented by a sine curve as shown in FIG. Therefore, the control is performed using a portion relatively close to a straight line in B in the figure.

[0006]

However, in the system using the above-described conventional 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. The rotation angle change amount is Δθ ₁ for the same corrected meander speed change amount ΔV ₁ depending on the position
[Delta] [theta] ₂ next corrected rotation angle will instead. Therefore,
Even if the meandering speed is detected, an error will occur unless the correction rotation angle is changed according to the position of the rotation angle θ of the eccentric cam, resulting in a problem that the correction accuracy is reduced.

Conventionally, in this method, control is mainly performed to prevent the belt from falling off the roll due to meandering, and since the belt position is controlled so as to be a constant value, the control is performed in the meandering direction and the belt position. Accordingly, the eccentric cam is rotated by a predetermined angle, and thereafter, the rotation amount of the eccentric cam is gradually reduced according to the meandering direction and the belt position to stabilize. Therefore, there was no problem even if the cam characteristic was not a perfect straight line as shown in FIG.

However, as described above, 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, there is a problem that the control is unstable and it takes time to converge. Further, in the color image forming apparatus, if the meandering control accuracy (for example, 0.1 mm) is poor, color shift occurs in a color image, and when performing control with high accuracy in order to solve this problem, The rotation angle of the eccentric cam must be detected by a sensor or the like, and control must be performed with an amount corresponding to the angle, resulting in complicated control.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem, and an object of the present invention is to provide an endless belt conveying device in an image forming apparatus capable of controlling the meandering of a belt with high accuracy and at low cost.

[0010]

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

[0011]

In the present invention, the belt meandering speed is calculated,
The cam rotation angle to be corrected is obtained based on the meandering speed, and the cam is rotated so that the belt meandering amount is zero. At this time, since the cam has a shape in which the meandering speed of the endless belt is constantly 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 conveying belt. The present invention is not limited to such an image forming apparatus,
The present invention is also applicable to a monochrome image forming apparatus, and is not limited to a transfer material transport belt, but is also applicable to an intermediate transfer body belt and a transfer material transport drum.

The transfer material transport belt 11 is in the form of an endless belt coated with a dielectric film, and is stretched over a plurality of rolls 12, 13, 14, 15 having at least a drive roll 12 and a tension applying roll 14, and is indicated by an arrow in the drawing. It is rotated in the A direction. Opposite to the upper surface of the transfer material transport belt 11, four sets of image forming units K, Y, M, and C for black, yellow, magenta, and cyan are provided.

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 unit 18, a developing machine 19, a transfer corotron 20, and an image carrier cleaner. 21 is provided downstream of the image forming units K, Y and M, and a transfer material neutralizing corotron 22 is provided, and the image carrier 16 is rotated in the direction of the arrow shown in the figure.

A peeling corotron 23 and a peeling claw 24 are provided downstream of the image forming unit C at the last stage, 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 disposed. On the downstream side of the drive roll 12, a suction corotron 30 is provided inside the transfer material transport belt, and a transfer material suction roll 31a is provided 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 is then transferred to the transfer material transport belt 11 by the suction cotorotron 30 and the transfer material suction roll 31 a.
Is adsorbed.

In the above-described color image forming apparatus, the image carrier 16 is uniformly charged by the charge corotron 17, the image of the document is exposed by the latent image writing means 18, and the electrostatic latent image is placed on the image carrier 16. An image is formed. Developing machine 1
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.
0, after transfer to the transfer material on the transfer material transport belt 11,
The toner remaining on the image carrier 16 is scraped off by the cleaner 21 to perform a series of image forming cycles. This cycle is performed by four image forming units K, Y,
The transfer is performed at M and C, and a plurality of toner images are sequentially superimposed and transferred onto the transfer material sucked 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 a direction perpendicular to the tension direction, the meandering speed V of the belt is proportional to the meandering correction roll angle α. and K _1. In addition, since the meandering speed V is determined by other factors such as a difference in circumferential length between both side ends of the belt, the parallelism of the rolls, and the like, the meandering speed V at α = 0 is meandered. These relationships are: V = ΔV−K
_{When the} meandering correction roll angle α is controlled so that the meandering speed V = 0, the correction roll angle change amount Δ
α = ΔV / K ₁ . Therefore, when the tilting mechanism displaces the roll end shown in FIG. 5B by the cam, assuming that the cam displacement change amount is ΔX, if the displacement is ΔX = L × tan Δα = L × tan (ΔV / K ₁ ), the meandering speed is increased. 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 =
ΔV / K ₂ . Therefore, if this relationship is established anywhere in the cam rotation angle θ, the cam rotation angle change Δθ is easily determined by detecting the meandering speed change ΔV.

From the above, ΔX = L × tan (Δθ × K
₂ / K ₁ ), the meandering speed change ΔV becomes constant with respect to the cam rotation angle change Δθ, and the constant is K ₂ . Become. Here, assuming that X = X ₀ when θ = 0, X = L × tan (θ × K ₂ / K ₁ ) + X ₀ ..., And the cam shape may satisfy this.

FIG. 2A is a plan view of a cam 48 according to the present invention, and FIG. 2B is a cam rotation angle θ of the cam 48 of FIG. 1A.
FIG. 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 one embodiment of the endless belt conveying device of the present invention. A pair of front and rear belt frames 3
A tension applying mechanism 36 is attached to 1 and 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 an inner end of the bracket 37, and a bracket 3.
7 and a slide rail 39 provided outside.
Further, both ends of the tension applying roll 14 are supported by support arms 40.
The projection 41 is formed inside the support arm 40 so as to be rotatable.

The projection 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 urged in the direction D in the drawing by the elastic force of the spring 37 to apply a predetermined tension to the belt.

One end of a release plate 42 is fixed to the spring 38 on the distal end 40a side of the support arm 40, and a bent portion 42a is formed at the other end of the release plate 42. The bent cam 42 is formed on the bent portion 42a. 43 and 44 are contacted. The release cams 43 and 44 are connected to the belt frame 3.
A release lever 46 is provided on the cam 43 on the front belt frame 31 side, which is attached to both ends of a cam shaft 45 penetrated between the cam shafts 1 and 32. With this structure, when the release lever 46 is in the state shown in the figure, the support arm 40 is urged to apply tension to the belt.
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
Reference numeral 7 is attached to the belt frames 31 and 32 so as to be rotatable about a shaft 47. Belt moving cams 48 and 49 for controlling the rotation of the bracket 37 are provided. It constitutes a tilting mechanism for tilting the shaft. The shape of the cams 48 and 40 is the shape 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 are attached to both ends of the cam shaft 50 penetrated between the belt frames 31 and 32, and the two belt moving cams 48 and 49, for example, when the cam shaft 50 rotates in the A direction in the drawing, the support arm on the near side. The support arm 40 is arranged so as to rotate in the direction B and the support arm 40 on the far side rotates in the opposite direction C. The camshaft 50 is connected to the motor 5
1 is driven to rotate.

The operation of the present invention having the above configuration 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 determined from the relationship shown in FIG. 2C based on the meandering speed, and a signal is sent to the motor 51 so as to reduce the belt meandering amount to zero. Output. As shown in FIG. 1, for example, when the cam shaft 50 is rotated in the direction A by the driving of the motor 51, the support arm 40 on the near side tilts in the direction B, and the support arm 40 on the back side moves in the opposite direction C. , So that the endless belt moves in the E direction. Thus, by controlling the inclination of the tension applying roll 14 in the axial direction, the center position of the belt is corrected to be a predetermined position.

In the above embodiment, the tension applying roll 14 is provided with a tilting mechanism for correcting meandering. However, the present invention is not limited to this. The other rolls are provided with a tilting mechanism, and this tilting mechanism is provided. The control may be performed by the 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 changed, and FIG. B is an enlarged sectional view.

In this embodiment, the tension applying roll 14
Is formed of an elastic member, and a plurality of ring-shaped slits 14a are formed in the surface thereof 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 supported between the side surface of the tension applying roll 14 and the support arm 40 via a thrust bearing 54, and a spring 56 is provided between the guide member 55 and the support arm 40. Is elastically supported by a guide member 55. On the opposite side of the support arm 40, a cam 48 rotated by a motor 51 is provided similarly to 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 shown in FIG. 1, the meandering speed is detected and the roll is tilted accordingly. In this embodiment, the roll 14 is tilted so that the load applied to the guide member 55 becomes a constant value. Let it. 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 that of the embodiment of FIG.

[0030]

As 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. And a cam for driving the tilting mechanism in a direction perpendicular to the tension applying direction, the cam having a shape for constantly increasing and decreasing 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 when applied to a color image forming apparatus, a high-quality image without color shift can be provided.

[Brief description of the drawings]

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

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

FIG. 3 shows another embodiment of the transfer material conveying apparatus 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 conveying belt.

FIG. 5 shows a conventional transfer material transport device, and FIG.
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 displacement of the eccentric cam.

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

[Explanation of symbols]

11: transfer material conveying belt, 12 to 15: roll, 48,
49: cams 40, 37, 47, 50: tilting mechanism

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B65H 5/02

Claims (1)

(57) [Claims] 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, a tilting mechanism for tilting an axis of at least one roll in a direction perpendicular to a tension applying direction. When,
A cam for driving the tilting mechanism, wherein the cam has a shape for constantly increasing and decreasing the meandering speed of the endless belt with respect to the cam rotation angle.