JPH02182640A - Image forming device - Google Patents

Abstract

PURPOSE:To make it possible to make a device small in size and to save electric power by arranging an electric charger which is faced with a form carrying belt, in the carrying direction close to the rear of a carrying roller arranged in such a way as to be faced with the carriage starting position of the form carrying belt. CONSTITUTION:A recording chart 14 which has been fed, is positioned while being held between a carrying roller 11 and a form carrying belt so as to be electrically charged in order by the charging action of a scorotron discharging device 16 so that the recording chart is sucked up onto the form carrying belt. In this case, electrostatic absorption is caused by electric charge which is induced on the opposite electrode 17 side of the form carrying belt while being reverse in electric charge induced to the surface of the recording chart. And each single color image is piled up at every printing station 181 through 184 so that a color image is thereby formed. In this color printer 15, a transfer roller 8 is eliminated at the first printing station 181, this is because high electric potential has to be maintained at the surface of the recording chart 14 so that a toner image is transferred by means of the surface electric potential, since there exists no member which abuts against the surface of it after the recording chart 14 has been directly charged by means of the scorotron discharging device 16.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrophotographic image forming apparatus that prints on printing paper that is electrostatically attracted to a paper transport belt and transported.

2. Description of the Related Art First, a conventional example of an image forming apparatus will be described with reference to FIG. In this image forming apparatus 1, an endless belt-like paper conveying belt 2 made of a galvanic material is stretched horizontally inside the apparatus, and four printing stations 3. ~3.
are arranged facing each other in sequence.

Therefore, these printing stations 3. The structure of ~34 will be explained. A photosensitive drum 4 is mounted on the upper surface of the paper conveyance belt 2.
are arranged to face each other, and above and in front of these photosensitive drums 4, an optical scanning device 5 and a developing device 6 are arranged to face each other. A transfer roller 8 serving as a transfer device connected to a power source 7 is disposed on the back side of the paper conveyance belt 2 at a position facing the photosensitive drum 4 . Furthermore, a toner cleaner 9, a charger 10, and the like are sequentially arranged facing each other on the circumferential surface of the photosensitive drum 4 extending from the transfer section to the scanning section. Further, at the end of the sheet conveyance belt 2 on the start side of conveyance rJN, a conveyance roller 11 is disposed facing from above and a charger 12 is disposed from below.

Further, a fixing device 13 is disposed opposite to the end of the paper conveyance belt 2 on the end of conveyance. Note that the developing device 6
For each printing station 3. ~3, every yellow,
Toners (not shown) such as magenta, cyan, and black are stored.

In such a configuration, first, the recording paper 14 fed into the device is pressed by the transport roller 11 and electrostatically attracted to the upper surface of the paper transport belt 2, which is charged by the discharge action of the charger 12. Therefore, each printing station 3. ~34 parts. At this time, in each of the printing stations 3 to 34, first, the photosensitive drum 4, which has been charged by the discharging action of the charging charger 10, is irradiated with laser light from the optical scanning device 5 to scan the electrostatic latent image, and the electrostatic latent image is scanned. When the latent image passes through the developing device 6, toner is applied to the latent image to form a monochrome image. Then, this monochrome image is transferred onto the recording paper 14 placed on the paper conveyance belt 2 by the discharge action of the transfer roller 8. In this way, the recording paper 14 on which the monochromatic images are sequentially printed is heated under pressure in the fixing device 13 and ejected from the device, and printing is completed.

Note that the photosensitive drum 4 after image transfer is cleaned by a toner cleaner 9.
The remaining toner is removed and the toner is recharged by the charger 10 in preparation for the next printing.

Problems to be Solved by the Invention As described above, in this image forming apparatus 1, the recording paper 14 is transported by being electrostatically attracted to the charged paper transport belt 2. In order to ensure this suction, the transport roller 11
The recording paper 14 is pressed against the paper conveyance belt 2 in 1.
-, the charge on the paper conveyance belt 2 flows out from the conveyance roller 11, and the surface potential of the recording paper 14 decreases. Therefore, in the conventional image forming apparatus 1, the charger 1 of the paper conveying belt 2
2, a discharge device for image transfer is required, and four transfer rollers 8 and the like are provided. For this reason, the power consumption of the image forming apparatus 1 is large, so the power supply section 7 becomes large, an insulating distance is required between each transfer roller 8, and the number of parts is large, making it difficult to downsize the apparatus.

Means for Solving the Problem In an electrophotographic image forming apparatus in which at least one printing station is provided at a position facing an endless belt-shaped paper transport belt stretched inside the device, a charging device facing the paper transport belt is used. The container is placed close to and behind the conveyance roller, which is disposed opposite the conveyance start position of the paper conveyance belt, in the conveyance direction.

By arranging the charger facing the paper conveyance belt in close proximity to the rear of the conveyance roller, which is placed opposite the conveyance start position of the paper conveyance belt, the recording paper positioned on the conveyance belt by the conveyance roller is charged by the charger. The recording paper is sequentially charged and reaches the printing station, and since the surface potential of the recording paper does not decrease, image transfer can be performed using this surface potential, making it possible to omit the discharging device at the printing station. .

Embodiment A first embodiment of the present invention will be explained based on FIG. In the color printer 15 which is this image forming apparatus, a scorotron discharge device 1 which is a charger is provided behind the conveyance roller 11.
6 is disposed, and a grounded counter electrode 17 is disposed at a position facing the scorotron discharge device 16 via the paper conveyance belt 2. Furthermore, the transfer roller 8 of the first printing station 18 is omitted. In addition,
The other structure is the same as that of the image forming apparatus 1 described above.

In this configuration, the image forming apparatus 15 has the following functions:
The recording paper 14 fed into the device is sandwiched and positioned between the transport roller 11 and the paper transport belt 2, and in this state is sequentially charged by the discharge action of the scorotron discharge device 16 and transferred to the paper transport belt 2. It is adsorbed. Note that this electrostatic adsorption is caused by the induction of a charge opposite to that on the surface of the recording paper 14 on the opposing electrode 17 side of the paper conveyance belt 2 .

Similarly to the image forming apparatus 1 described above, each printing station 18. ~18. A color image is formed by overprinting monochrome images each time. Furthermore, this color printer 15
In the first printing station 18, there is no transfer roller, but this is because after the recording paper 14 is directly charged by the scorotron discharge device 16, there is no member that contacts the surface, so a high potential is recorded. maintained on the surface of the paper 14;
This is because the toner image is transferred by this surface potential. Note that the output of the scorotron discharge device 16 and the printing station 18. It is also possible to omit all the transfer rollers 8 by improving the insulation properties of the parts 184 to 184.

Next, a second embodiment of the present invention will be described based on FIG. 2. In the color printer 19 which is this image forming apparatus, a conveyor belt 2 having a dielectric layer 20 on the front surface and a conductive layer 21 on the back surface is used.
2 are provided and all printing stations 23. The groove structure is similar to that of the image forming apparatus 15 described above, except that the transfer roller 8 and the counter electrode 17 of 234 to 234 are omitted.

In such a configuration, this image forming apparatus 19 functions similarly to the image forming apparatus 15 described above.

In this image forming apparatus 19, a potential sufficient for four transfers is applied to the recording paper 14 by the scorotron discharge device 16, and furthermore, a conductive layer 21 located on the back surface of the conveyor belt 22 provides a potential for transferring the recording paper 14 four times. All transfer rollers 8 are omitted so that the surface potential is maintained well.

In these embodiments, the image forming apparatus 15.19 is connected to a plurality of printing stations 18. ~184.23, ~23.
However, the present invention is not limited to this, and can also be applied to a monochrome printer with one printing station.

Effects of the Invention As described above, the present invention has the charger facing the paper conveyance belt placed close to the rear in the conveyance direction of the conveyance roller which is disposed opposite to the conveyance start position of the paper conveyance belt. The recording paper positioned above is charged sequentially by the band t1 device, is well attracted to the conveyor belt, and reaches the printing station. Since the surface potential of the recording paper does not decrease, this surface potential is used to transfer the image. Since the discharge device of the printing station can be omitted, the power consumption of the image forming device can be reduced, the power supply unit can be made smaller, no insulation distance is required between the printing stations, and the number of parts can be reduced. This has the effect of reducing the size of the image forming apparatus and reducing power consumption.

[Brief explanation of the drawing]

FIG. 1 is a vertical side view of a first embodiment of the present invention, FIG. 2 is a vertical side view of a second embodiment, and FIG. 3 is a vertical side view of a conventional example. 2.22... Paper conveyance belt, 15.19... Image forming device, 16... Charger, 18. ~18. ,23～
23.・・・Printing station

Claims (1)

[Claims] In an electrophotographic image forming apparatus in which at least one printing station is provided at a position facing an endless paper conveyance belt stretched inside the device, a charger facing the paper conveyance belt is connected to the paper conveyance belt. An image forming apparatus characterized in that the image forming apparatus is disposed in close proximity to the rear of a conveyance roller in a conveyance direction, which is disposed to face a conveyance start position.