JPH0640590A - Endless belt conveying device in image forming device - Google Patents

Abstract

PURPOSE:To detect meandering of a belt accurately. CONSTITUTION:An image forming device in which an endless belt 11 is applied expandedly on multiple rotating rollers 13 to drive them is provided with a pair of belt frames 31 and 32, a pair of supporting arms 33 installed on the pair of belt frames 31 and 32, the rotating rollers of which both ends are pivoted rotatably on the pair of supporting arms, and load detectors 35 installed at both ends of the rotating rollers 13 between the belt frames 31 and 32 and supporting arms 33. Thus, the amount of movement of the endless belt 11 in axial direction is calculated based on output signals from both load detectors 35.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoconductor in an image forming apparatus such as a copying machine or a printer using an electrophotographic system.
The present invention relates to an endless belt transport device used for a transfer material transport body, an intermediate transfer body, a continuous paper transport body, and the like.

[0002]

2. Description of the Related Art The endless belt conveying device in the above image forming apparatus is constructed such that the endless belt is stretched and driven by a driving roll and a tension applying roll. A phenomenon in which the belt moves in a direction perpendicular to the transport direction, that is, a meandering phenomenon may occur due to an error between the rolls or an error in the axes of the rolls that should be originally parallel. However, when the meandering phenomenon occurs, the image formed on the belt or the image transferred on the belt is biased, so that a good image cannot be obtained.

In order to solve this problem, JP-A-57-
Japanese Patent Laid-Open No. 139777 proposes a method of detecting the meandering of the belt and controlling the belt position correcting device by the detection signal. This will be described with reference to FIGS. 7 and 8. In FIG. 7, the contact piece 20a is brought into contact with the end portion 2a of the belt 2, and the movement of the contact piece 20a is detected by the optical sensor 3.
1a and 31b are read to detect the displacement of the belt,
In FIG. 8, marks 57a, 5 are provided on both ends of the belt 2.
7b, and use this mark as the optical sensor 58a, 58b.
The belt displacement is detected by reading.

[0004]

However, in the conventional method of detecting the meandering of the belt, in the method of contacting the contact piece 20a with the belt end 2a shown in FIG. 7, the belt end 2a and the contact piece 2a are contacted with each other. Since the followability of the belt 20a and the straightness of the belt end 2a affect the detection accuracy, wear, cracks, dirt, foreign matter adhesion, etc. of the belt end 2a or the contact piece 20a lowers the detection accuracy and lowers the reliability. In addition, in the method of reading the marks 57a and 57b formed on the belt 2 shown in FIG. 8, the accuracy of forming the marks 57a and 57b and the optical sensors 58a and 58b are high.
There is a problem that the cost is high if the accuracy of 1 determines the detection accuracy and the high-accuracy detection is performed, and that accurate detection cannot be performed due to stains on the marks 57a and 57b.

An object of the present invention is to solve the above problem and to provide an endless belt conveying device in an image forming apparatus capable of detecting the meandering of a belt with high accuracy.

[0006]

In order to achieve the above object, the invention according to claim 1 of the present invention is an image forming apparatus in which an endless belt is stretched and driven by a plurality of rotating rolls. A load detector for detecting a load applied to both sides of the rotating roll by a tension of the belt is provided, and an axial movement amount of the endless belt is calculated based on an output signal of both load detectors. Examples include a pair of belt frames, a pair of support arms provided on the pair of belt frames, a rotating roll whose both ends are rotatably supported by the pair of supporting arms, and the rotating roll. A load detector provided between the belt frame and the support arm on both sides of the load detector.

The invention according to claim 2 of the present invention is
A pair of belt frames, a pair of support arms provided on the pair of belt frames via a tension applying mechanism, a rotation roll whose both ends are rotatably supported by the pair of support arms, and the rotation. A displacement amount detector provided between the belt frame and the support arm on both sides of the roll is provided, and an axial movement amount of the endless belt is calculated based on an output signal of both displacement amount detectors. And

It should be noted that the moving speed may be calculated from the axial moving amount, or the belt tilt is controlled by controlling the axial tilt of the rotating roll based on the axial moving amount or moving speed. It may be modified.

[0009]

In the present invention, the load acting on both ends of the rotating roll that stretches the endless belt is detected, and the amount of axial movement of the endless belt is calculated from the difference between them, for example, the amount of movement is set to zero. The axial tilt of the rotating roll is controlled so that the central position of the belt is corrected to the central position of the rotating roll.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 6 is an overall configuration diagram of a color image forming apparatus showing an example to which the present invention is applied. The present invention is not limited to such a color image forming apparatus, but can be applied to a monochromatic image forming apparatus. Further, the present invention is not limited to the transfer material transport belt, but can be applied to a photoconductor, an intermediate transfer body, a continuous paper transport body, and the like.

A transfer material conveying belt, which is an endless belt 11 made of a dielectric film, includes rotating rolls 12, 13, and 1.
The endless belt 11 is stretched around 4 and 15 and is rotated in the direction of the arrow A in the drawing by the driving of the rotating roll 12, and the rotating roll 14 applies tension to the endless belt.
Four sets of image forming units K, Y, M, and C for black, yellow, magenta, and cyan are arranged on the upper surface of the transfer material transport belt 11 so as to face each other.

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.

On the downstream side of the image forming unit C at the final stage, a peeling corotron 23 and a peeling claw 24 are provided, and a fixing device 25 is further provided. A belt static elimination corotron 26 and a cleaning blade 27 are arranged on the upstream side of the rotating roll 12. The transfer material in the paper feed tray 28 is conveyed to the endless belt 11 by the feed roll 29, and then adsorbed and conveyed to the endless belt 11.

In the above-mentioned color image forming apparatus, the image carrier 16 is uniformly charged by the charge corotron 17, the original image is exposed by the latent image writing means 18, and the electrostatic latent image is formed 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 superimposed and transferred onto the transfer material that is attracted and conveyed by the endless belt 11.

FIG. 1 is a schematic diagram showing the principle of detecting the meandering of the belt in the endless belt conveying device of the present invention. The endless belt 11 is stretched around the rotating rolls 12, 13, 14 and driven by the rotating roll 12, and the rotating roll 14 biased by the spring S applies tension T to the endless belt 11. There is. If the wrap angle of the endless belt 11 wrapped around the rotating roll 14 is 2θ, the loads F ₁ and F ₂ acting on both ends of the rotating roll 14 in the wrap center direction are represented by F ₁ + F ₂ = 2Tsin θ. Now, the distance between both ends of the rotating roll 14 is 2L.
Then, when the center of the endless belt 11 is on the center of the roll, F ₁ and F ₂ coincide with each other, and F ₁ = F ₂ = Tsin θ. From here, when the endless belt 11 is moved x in the axial direction of the rotating roll, F ₁ = [(L + x) / L] T sin θ, and F ₂ = [(L−x) / L] T sin θ. Therefore, when the difference between the two is taken, F ₁ −F ₂ = (2x / L) T sin θ, and the axial movement amount x of the endless belt can be calculated by x = L (F ₁ −F ₂ ) / 2T sin θ. . The above calculation method can be applied to the other rotating rolls 12 and 13. Therefore, the loads F ₁ and F ₂ acting on both ends of at least one of the rotating rolls 12, 13 and 14 can be calculated. The meandering of the endless belt can be detected by detecting it and calculating the axial movement amount x of the endless belt.

It should be noted that F ₁ and F ₂ can be similarly obtained by dividing the angle deviated from the lap center by cos α, instead of the load in the lap center direction. Alternatively, the moving speed x may be differentiated to calculate the moving speed.

FIG. 2 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 support arm 33 is rotatably attached to each of the shafts 1 and 32 around a shaft 34, and a rotary roll 13 is rotatably supported by the tip of the support arm 33. A load detector 35 is arranged between the support frames 33 on both sides that pivotally support the rotating roll 13 and the belt frames 31 and 32, and loads F ₁ and F ₂ acting on both ends of the rotating roll 13 are provided. Can be detected.

FIG. 3 is a perspective view showing an embodiment of the tension applying mechanism according to 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.
Both ends of the rotating roll 14 are rotatably supported by the support arm 40, and the protrusion 4 is provided inside the support arm 40.
1 is formed.

The projection 41 of the support arm 40 is fitted in 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, and belt moving cams 48 and 49 for controlling the rotation of the bracket 37 are provided. 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. FIG. 4 shows a block diagram of the control system in the present invention.
The load acting on both ends of the rotating roll 13 is detected by the load detector 3.
5a and 35b, the belt movement amount calculation unit 52 calculates the axial movement amount x of the endless belt based on the difference between the loads F ₁ and F ₂ based on the principle of FIG. 1, and the motor drive circuit 53 performs the movement. A signal is output to the motor 51 so that the quantity x becomes zero. When the motor 51 is driven, FIG.
For example, when the cam shaft 50 rotates in the A direction, the support arm 40 on the front side rotates in the B direction, and the support arm 40 on the back side rotates in the reverse C direction, as shown in FIG. The belt moves in the E direction. In this way, by controlling the inclination of the rotating roll 14 in the axial direction, the center position of the belt is corrected to the center position of the rotating roll 14. Alternatively, the moving amount x in the axial direction may be differentiated to calculate and correct the moving speed.

Next, another embodiment of the present invention will be described with reference to FIG. This embodiment is applied to the example in which the rotating roll 14 described in FIG. 3 is biased by the tension applying mechanism 36, and the bracket 37 of the tension applying mechanism 36.
A displacement amount detection sensor 52 for detecting the displacement amount of the support arm 40 is provided between the support arm 40 and the support arm 40. And
The amount of displacement detected is converted into a load, and the belt position is corrected in the same manner as described above.

[0024]

As is apparent from the above description, according to the present invention, in an image forming apparatus in which an endless belt is stretched around a plurality of rotating rolls and driven, both sides of the rotating roll are tensioned by the tension of the endless belt. Equipped with a load detector that detects the load applied to the section, and the axial movement amount of the endless belt is calculated based on the output signals of both load detectors. The belt movement amount can be accurately detected without contact, and the belt movement amount can be detected without contacting the belt end portion or the like, so that the belt is not damaged and the belt is not marked. It is possible to detect the movement amount due to the meandering of the belt with high accuracy with a simple and inexpensive structure.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining the principle of detecting the meandering of a belt in an endless belt conveyance device of the present invention.

FIG. 2 is a perspective view showing an embodiment of an endless belt conveyance device of the present invention.

FIG. 3 is a perspective view showing an embodiment of a tension applying roll according to the present invention.

FIG. 4 is a configuration diagram of a control system according to the present invention.

FIG. 5 is a side view showing another embodiment of the present invention.

FIG. 6 is an overall configuration diagram of a color image forming apparatus showing an example to which the present invention is applied.

FIG. 7 is a view for explaining a conventional method for detecting meandering of a belt.

FIG. 8 is a view for explaining a conventional method for detecting meandering of a belt.

[Explanation of symbols]

11 ... Endless belt, 12, 13, 14 ... Rotating roll, 3
1, 32 ... Belt frame, 33, 40 ... Support arm,
35 ... Load detector, 36 ... Tension applying mechanism, 52 ... Displacement amount detector

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area G03G 15/16

Claims (5)

[Claims] 1. An image forming apparatus in which an endless belt is stretched and driven by a plurality of rotating rolls, comprising a load detector for detecting a load applied to both sides of the rotating roll by tension of the endless belt. An endless belt conveying device, wherein an axial movement amount of an endless belt is calculated based on an output signal of a load detector. 2. A pair of belt frames, a pair of support arms provided on the pair of belt frames, a rotating roll whose both ends are rotatably supported by the pair of supporting arms, and the rotating roll. The endless belt conveyance device according to claim 1, further comprising: load detectors provided between the belt frame and the support arm on both sides of the belt. 3. An image forming apparatus in which an endless belt is stretched around a plurality of rotating rolls and driven, and a pair of belt frames, and a pair of support arms provided on the pair of belt frames via a tension applying mechanism. The pair of support arms includes a rotating roll whose both ends are rotatably supported, and a displacement amount detector provided between the belt frame and the supporting arm on both sides of the rotating roll. An endless belt conveying device, wherein an axial movement amount of an endless belt is calculated based on output signals of both displacement amount detectors. 4. The endless belt conveying device according to claim 1, wherein a moving speed is calculated from the moving amount in the axial direction. 5. The belt position is corrected by controlling the inclination of the rotating roll in the axial direction on the basis of the amount of movement or the moving speed in the axial direction, to correct the belt position. Endless belt conveyor.