JPH05193772A - Image forming device - Google Patents

Abstract

PURPOSE:To improve assembling ability and maintainability of a cleaning blade used for an image transfer belt, in an electronic photograph type image forming device wherein an endless belt-like image transfer belt is rotatably stretched in a position facing a print station. CONSTITUTION:A cleaning blade 20 and a cleaner container 18 are arranged below an image transfer belt 8. A weight roller 21 for pressing the image transfer belt 8 against the cleaning blade 20 by its head weight is provided and a blade drive mechanism 19 for displaceably supporting the cleaning blade 20 and varying a contact angle with the under surface of the image transfer belt 8 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus in which a latent image carrier of a printing station is arranged on an image transfer belt such as a sheet conveying belt or a transfer belt.

[0002]

2. Description of the Related Art In recent years, electrophotography has been developed as one of electrostatic image forming methods. In this technique, an electrostatic latent image is formed on a photoconductor, which is a charged latent image carrier, by optical scanning or the like, and the electrostatic latent image is developed with charged toner and transferred to a printing paper. An image forming apparatus using this electrophotographic method is provided with a printing station in which at least a charging device, an exposing device, and a developing device are arranged to face each other on the surface of a latent image carrier such as a photosensitive belt, and an endless belt-shaped image transfer is performed. For example, the belt is stretchably stretched, and the latent image carrier of the printing station is arranged to face the image transfer belt.
As such an image transfer belt, there are a transfer belt for holding and carrying a toner image, a paper carrying belt for carrying printing paper, and the like.

Here, in such an image forming apparatus, for example, if scattered toner or the like adheres to the surface of the image transfer belt, the toner image and the printing paper are contaminated. A belt cleaner for cleaning the surface of the belt is generally provided. In such a belt cleaner, for example, a cleaner container having an open upper portion is arranged at a position facing the image transfer belt from below, and a cleaning blade that scrapes the lower surface of the image transfer belt above the opening of the cleaner container. It has a structure in which is arranged.

[0004]

In the image forming apparatus provided with the belt cleaner as described above, the front surface of the image transfer belt can be kept clean, so that the back surface of the printing paper can be prevented from being soiled. .. Here, in such an image forming apparatus, the cleaning blade is generally fixed so as to face the surface of the image transfer belt, but the contact angle between the cleaning blade and the surface of the image transfer belt is not good. And the performance of the belt cleaner will be significantly reduced.

Therefore, in the conventional image forming apparatus, the contact angle between the cleaning blade and the image transfer belt is made variable by, for example, disposing the cleaning blade with a bolt in a long hole formed in the body frame. .. However, in this case, it is necessary to manually operate the bolt inside the device in order to adjust the contact angle between the cleaning blade and the image transfer belt, and the work is complicated and the assemblability and maintainability are deteriorated.

The present invention provides an image forming apparatus in which the cleaning blade is easy to assemble and maintain.

[0007]

A printing station in which at least a charging device, an exposing device, and a developing device are arranged in opposition to each other is provided on the surface of a latent image carrier, and the printing station is endless at a position opposed to the latent image carrier. A belt-shaped image transfer belt is rotatably stretched, and a cleaner container having an open top is arranged at a position facing the image transfer belt from below, and the lower surface of the image transfer belt is placed above the opening of the cleaner container. A cleaning blade to be rubbed is arranged, and a weight roller is arranged on the leading edge portion of the cleaning blade so as to be vertically movable by its own weight through the image transfer belt, and the cleaning blade is movably supported to support the image. A blade drive mechanism for changing the contact angle with the lower surface of the transfer belt is provided.

[0008]

Since it is not necessary to displace the cleaning blade by manually attaching and detaching the bolt inside the apparatus as in the conventional apparatus, it is possible to obtain an image forming apparatus having good assembling property and maintenance property of the cleaning blade. ..

[0009]

Embodiments of the present invention will be described with reference to the drawings.
First, the color printer 1 which is the image forming apparatus of the present embodiment.
Then, as illustrated in FIG. 2, on the outer peripheral surface of the photosensitive drum 2 which is a rotatable latent image carrier, a drum cleaner 3, a drum charger 4, an exposure device, a laser scanner 5, yellow, magenta, and cyan. And black toner (not shown)
There are provided four printing stations 7 _{1 to} 7 ₄ in which developing devices 6 and the like each storing therein are sequentially opposed to each other. The photosensitive drums 2 of these printing stations 7 _{1 to} 7 ₄ are rotatably stretched. It is disposed opposite to the sheet conveying belt 8 which is an endless belt-shaped image conveying belt.

Here, a sheet feeding device 10 is disposed in proximity to one end of the sheet conveying belt 8 in the stretching direction, with a sheet holding roller 9 interposed therebetween, and a transfer charger 11 is provided on the upper surface of this position.
Are opposed to each other. Further, a fixing device 12 which also serves as a paper discharging mechanism is disposed opposite to one end of the paper conveying belt 8 on the side opposite to the paper feeding device 10 and the like in a stretching direction, and is stretched substantially horizontally. A belt static eliminator 13 and a belt cleaner 14 are arranged opposite to each other at a position facing the lower surface of the paper transport belt 8.

The sheet conveying belt 8 has a structure in which a conductive layer (both not shown) is formed under the insulating layer located on the surface, and two rotary rollers 15 which are in contact with the conductive layer are provided. An earth line (not shown) is connected to one of 16 or the like. Further, a belt support roller 17 is arranged at a position facing the photosensitive drums 2 of the printing stations 7 _{1 to} 7 ₄ via the paper transport belt 8, and a power source is provided below the paper transport belt 8. A circuit (not shown) and the like are arranged.

As shown in FIG. 1, the belt cleaner 14 of the color printer 1 movably supports a cleaning blade 20 on a cleaner box 18 which is a cleaner container having an open top by a blade drive mechanism 19. A weight roller 21 is arranged on the leading edge of the cleaning blade 20 via the paper transport belt 8 so as to be vertically movable by its own weight. Here, the blade drive mechanism 19 pivotally supports a swing arm 22 having the cleaning blade 20 exchangeably mounted at its tip end so as to be rotatable about its center.
The end portion of 2 is biased downward by a spring 23 and is held by an eccentric cam 24.

The cleaning blade 20, which is movably supported by the blade drive mechanism 19 as described above, is tilted forward so as to face the moving direction of the sheet conveying belt 8. The blade drive mechanism 19 allows the contact angle of the lower surface of the paper transport belt 8 to be slightly changed. Further, the weight roller 21 is rotatable and vertically movable by engaging the rotary shaft 25 projecting at both ends with the long hole 27 of the belt frame 26. It is tilted rearward along the moving direction of the paper transport belt 8. Therefore, the weight roller 21, which moves by its own weight within the elongated hole 27 that is tilted backward, holds the paper transport belt 8 at the leading edge of the cleaning blade 20 displaced by the position adjustment of the blade drive mechanism 19. It is designed to make pressure contact with the pressing force of.

[0014] In such a configuration, in the color printer 1 when performing printing of a color image, the respective printing station 7 _{1-7 4,} the residual toner or the like is removed by the drum cleaner 3 at the discharge of the drum charger 4 The electrostatic latent image formed by the optical scanning of the laser scanner 5 on the outer peripheral surface of the charged photosensitive drum 2 is developed into a monochromatic image of each color by the toner supplied from the developing device 6. Then, in synchronization with the operation of the printing stations 7 _{1 to} 7 ₄ as described above, the printing paper (not shown) is supplied from the paper feeding device 10 onto the paper transport belt 8 by the rotation of the paper holding roller 9, and the printing paper Is electrostatically attracted onto the sheet conveying belt 8 by the discharge of the transfer charger 11, and a transfer voltage is supplied. Therefore, the printing paper conveyed is
Equipment from the photosensitive drum 2 of each of the printing stations 7 _{1-7 4} on the surface yellow, magenta and is cyan and monochrome images are sequentially overprint black, after being pressurized heated with a release to the fixing device 12 from the sheet conveying belt 8 It is discharged to the outside.

On the other hand, the paper transport belt 8 from which the printing paper has been peeled off as described above continues to roll, and the surface thereof is neutralized by the corona discharge of the belt neutralizer 13. Then, the destaticized sheet transport belt 8 is cleaned of dust such as toner and paper dust adhering to the surface thereof by rubbing the cleaning blade 20 of the belt cleaner 14, and stands by for the next printing.

Here, the belt cleaner 14 of the color printer 1 has the swing arm 2 when the eccentric cam 24 rotates.
2 swings to displace the cleaning blade 20, and the contact angle between the cleaning blade 20 and the sheet conveying belt 8 changes. By doing so, for example, it is not necessary to displace the cleaning blade 20 by manually attaching and detaching the bolt inside the device as in the conventional device,
Cleaning blade 20 by blade drive mechanism 19
Since the contact angle between the belt cleaner 14 and the paper transport belt 8 is easily adjusted, the belt cleaner 14 has good assemblability and maintainability. Furthermore, with this belt cleaner 14,
Since the weight roller 21 that presses the sheet conveyance belt 8 against the cleaning blade 20 that is displaced as described above moves by its own weight, the cleaning blade 20 and the sheet conveyance belt 8 are not changed even if the contact angle changes. The pressure contact force is maintained constant. The eccentric cam 24 that adjusts the displacement of the cleaning blade 20 as described above is connected to, for example, a manual lever or a servo motor (both not shown) so that the rotation angle can be easily adjusted. Is becoming

Here, in the color printer 1, the rotation shaft of the swing arm 22 supporting the cleaning blade 20 is engaged with the U groove of the upper opening of the support frame (not shown) from above, and the sheet is conveyed. The belt 8 can be easily attached and detached when it is replaced. Since the center of rotation of the swinging arm 22 pivotally supported in this way is located below the line of action of the reaction force that acts on the cleaning blade 20 from the sheet conveying belt 8, the cleaning blade 20 moves to the sheet conveying belt. When the lower surface of 8 is rubbed, the swing arm 22 does not separate from the support frame.

Further, here, the paper transport belt 8 for electrostatically adsorbing and transporting the printing paper has been exemplified as the image transport belt, but as such an image transport belt, a transfer belt for electrostatically attracting and transporting the toner image. Etc. are also possible.

[0019]

As described above, the present invention provides a printing station in which at least a charging device, an exposing device and a developing device are arranged on the surface of a latent image carrier, and the printing station is opposed to the latent image carrier. The endless belt-shaped image transfer belt is rotatably stretched at a position where the image transfer belt is placed, and a cleaner container with an open top is arranged at a position facing the image transfer belt from below, and the image transfer is performed above the opening of the cleaner container. A cleaning blade for rubbing the lower surface of the belt is arranged, and a weight roller is arranged on the leading edge portion of the cleaning blade via the image transfer belt so as to be vertically movable by its own weight, and the cleaning blade is movably supported. Further, by providing a blade drive mechanism for varying the contact angle with the lower surface of the image transfer belt, for example, as in the conventional device, the vowel inside the device is changed. It is not necessary, such as to displace the cleaning blade and removable manually bets are those having an effect such as can be assembling property and maintainability of the cleaning blade to obtain a good image forming apparatus.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a main part of an embodiment of the present invention.

FIG. 2 is a vertical sectional side view showing the whole.

[Explanation of symbols]

 2 latent image carrier 4 charger 5 exposure device 6 developing device 7 printing station 8 image transfer belt 18 cleaner container 19 blade drive mechanism 20 cleaning blade 21 weight roller

Claims (1)

[Claims] 1. A printing station in which at least a charging device, an exposing device, and a developing device are arranged in opposition to each other on the surface of a latent image carrier, and an endless belt-shaped image transfer is made to a position of the printing station opposed to the latent image carrier. A cleaning blade that stretches the belt rotatably, arranges a cleaner container having an upper opening at a position facing the image transfer belt from below, and rubs the lower surface of the image transfer belt above the opening of the cleaner container. The weight roller is arranged on the leading edge of the cleaning blade via the image transfer belt so as to be vertically movable by its own weight, and the cleaning blade is displaceably supported to support the lower surface of the image transfer belt. An image forming apparatus comprising a blade drive mechanism for varying a contact angle with the blade.